Meanwhile, the density of the samples sintered with NH4(HCO3) was found to decrease with an increase in NH4(HCO3) content. This indicates an increase in porosity of the samples. The glass compositions reached an open porosity of more than 60% at the addition of 70 vol.% NH4(HCO3). In addition, SEM micrograph revealed large pores with good interconnection between the pores.In this work the sintering ability of borosilicate (S53B50), borophosphate (P40B10) and phosphate (Sr) bioactive glasses was investigated. The glass powders were crushed and sintered in air at a heating rate of 10 °C/min for 2 hours at sintering temperatures between 480 °C–600 °C. The aim was to define the optimum sintering temperature prior to glass crystallization. The density of the samples was found to decrease when the temperature was increased up to 580 °C; probably due to the inhibition of the viscous flow of the particles during sintering thereby reducing the densification of the material. Such low porosity is not suitable in tissue engineering. To process highly porous scaffolds with porosity required for scaffold applicable to tissue engineering, the powders were further mixed with 60 vol.% and 70 vol.% of NH On the other hand, allografts are subject to cleaning and preparation processes designed to remove cells to minimize immune response. In addition, these process techniques potentially reduce the osteoinductivity, osteoconductivity, and mechanical strength of the graft3. Therefore investigation of biomaterials which could be used in the repair and regeneration of bones remains of paramount importance.The large number of bone defects caused from a disease or trauma still remains a significant clinical challenge. At present, autografts and allografts are mainly used in the repair of defected bones. These grafts offered all the desired properties required for bone repair and regeneration, which are osteoconductivity, osteogenesis, and osteoinductivity. However, bone grafts are associated with high operating costs for harvesting the graft, limited availability, donor site morbidity and complications including infection, pain, and hematoma® (45S5) with composition in the SiO2-CaO-Na2O-P2O5 system discovered by Hench et al.4 Bioglass®, as well as other similar glass compositions, such as BonAlive(R) (S53P4) were found to rapidly form a chemical bond with bone through the precipitation of a hydroxyapatite layer at the glass surface. The mechanism enabling strong bone/glass interface has been reviewed in detail in the past5. However, typical silicate bioactive glasses have two major drawbacks despite their bond forming abilities. These include their poor mechanical properties (caused by their amorphous nature) and their tendency to crystallize during sintering7.One such biomaterial is bioglasset al.8, the presence of crystalline phases formed during heat treatment tend to retard the formation of the hydroxyapatite layer, hence glass becomes less bioactive in simulated body fluid. Therefore, crystallization should be prevented whenever possible. This becomes an issue to overcome, as in order to obtain clinically relevant construct, the graft should be a 3D structure with large pore size (>100 µm) and porosity (>70%). The construct should have mechanical properties similar to the tissue to be replaced and should be prepared in a reproducible manner. Typical 3D scaffold manufacturing involves a firing and sintering step which will lead, in most cases, to crystallization of the glass9.According to Filho 2 content have been developed. Phosphate and borophosphate glasses have been found to not only be promising as biomaterials11, but also allows hot forming at temperature below their crystallization domain13. Borosilicate glasses also demonstrated to have thermal properties enabling hot forming more readily than typical silicate bioactive glasses14. Not only these glasses have enhanced hot forming domain but they were also found to promote cell adhesion and proliferation as well as differentiation into bone cells15.Over the years new glass compositions with no or lower SiOet al.16, studied the preparation of porous ceramics by viscous slurry foaming using hydroxyapatite powder and ammonium hydrogen carbonate as the foaming agent for the generation of pores in the glycerol-based viscous ceramic slurry. Open and total porosity were found to increase from 25 to 69% and from 32 to 73% when NH4(HCO3) content was varied from 0 to 2.75 wt.%. The sintered ceramics were found to have well-connected, irregularly shaped pores. Meanwhile, Kazutaka et al.17, produced highly porous alumina based ceramics by incorporating polymethylmethacrylate (PMMA) microspheres with different diameters as a template and MgO or SiC powder as a sintering aid and subsequent calcinations at 1600 °C. The sintered ceramics formed spherical pores which correlated to the morphology of the PMMA microspheres. Highly porous and mechanically strong alumina-based ceramics having an open porosity of 62%, a connected space size of 1.3 µm, and a compressive strength of 147.6 MPa were fabricated by incorporating PMMA microspheres with a mean particle size of 22.6 µm and an appropriate amount of SiCLocs 4(HCO3).This work aims to determine the time-temperature conditions that allow for the sintering of a borosilicate (S53B50), borophosphate (P40B10) and phosphate (Sr) with minor or no crystallization as well as the fabrication of porous scaffolds using NHThe three glasses under investigation were processed with the composition presented in Table g) is taken at the inflection point of the endotherm (obtained by taking the first derivative of the curve) and Tx is defined as the onset of the crystallization peak. The working range (or hot forming domain) was defined as ΔT=Tx−Tg. In this study, the crystallization temperature (Tp) which is at the maximum of the exothermic peak was not measured. The quantified values are presented in Table Figure 4(HCO3). The patterns showed that the bioactive glasses were amorphous and free of any significant crystalline phases.Figure Figure 4(HCO3), it is important to note that the NH4HCO3 was added after milling. The glasses were amorphous and had no significant crystalline phases after milling and the glass particles also exhibited irregular shapes with a wide size distribution (results not shown). The average particle size of S53B50, P40B10 and Sr were 39.9 µm, 32.8 µm and 46.3 µm respectively, with this said, it is noteworthy to mention that the large particle size obtained for these glasses was due to the small force that was used during crushing compared to the force applied during crushing of the glasses that were prepared without NH4(HCO3). This increase in particle size was crucial in that, fine particles were reported to enhance crystallization of bioactive glass powders7.Similar results were observed for the bioactive glass powders prepared with NH4(HCO3) are shown in Fig. Samples were sintered at temperatures between 480 and 600 °C. The obtained densities of the sintered bioactive glasses without NHGlass P40B10 samples showed the same trend, but with slightly lower densification than S53B50 and Sr, this may be due to high activation energy for viscous flow for this particular glass composition. The maximum densification  achieved for glasses S53B50, P40B10 and Sr were 93%, 72% and 92% respectively.4(HCO3) for each sintering temperature. As the sintering temperature was increased, the samples began to crystallize as evidenced by the presence of sharp diffraction peaks. As expected, the crystallization occurs at lower temperature than Tx due to the small particle size used compared to the one analyzed by DTA.Figure SEM investigations of the sintered bodies’ cross sections in Fig. 4(HCO3) was too low for tissue engineering application therefore; a second batch of experiments was conducted with the addition of NH4(HCO3) with the aim of increasing the porosity of the samples. Table The porosity from the sintered samples without NH4HCO was too 4(HCO3) content was increased. A similar trend was observed by Locs et al.16, whereby the open and total porosity were found to increase from 25 to 69% and from 32 to 73% when NH4(HCO3) content was varied from 0 to 2.75 wt.%. The glass compositions reached an open porosity of more than 60% at the addition of 70 vol.% NH4(HCO3), with glass Sr obtaining the highest open porosity of 72% TD. SEM analysis of the cross sections in Fig. 4(HCO3)16. It is known that porosity decreases the density of the materials as confirmed by the densification results. The interconnection between the pores is clearly presented in the SEM micrographs. Homogeneity of pore distribution is also evident on the cross section of the scaffolds. All the glasses had a similar microstructure.The porosity of the scaffolds was found to increase as the NH18.In addition, the pore walls were composed of dual microstructures (results not shown) with micro pores observed on the pore struts as well as all over the surface; this was probably due to the gas released during the sintering process. However, the micro pores were only clearly visible on glass P40B10 and Sr. The presence of micro pores is an important feature of these scaffolds, as it is known that small pores favour cell adhesion and allow the physiological fluids to enter the inner part of the scaffoldThe scaffolds were investigated by XRD to check for the presence of any crystalline phase formed during sintering. The XRD patterns for glass S53B50 and P40B10; shown in Fig. 19. Particle sizes for samples prepared without NH4(HCO3) were in average 20.5 µm, 18.4 µm and 26.4 µm for glass S53B50, P40B10 and Sr respectively, while the average particle sizes for the glass powders sintered with NH4(HCO3) was 39.9 µm, 32.8 µm and 46.3 µm for S53B50, P40B10 and Sr respectively. Fine particles are known to increase the number of nucleation sites by increasing surface to volume ratio thus increasing the crystallization kinetics of glasses with surface initiated crystallization19. Aside from the particles size which might affect the crystallization kinetics, the presence of carbon, from the binder, at the particles surface may inhibit crystallization.The particle size is known to play a critical role in sintering as well as in crystallization4(HCO3) content are shown in Fig. 4(HCO3) as observed with the SEM analysis. There is also clear visual evidence of the high interconnectivity and porosity of the scaffolds. In addition, there appears to be a homogenous distribution of pores which are distributed uniformly all over the scaffolds. This trend was observed for glass P40B10 and Sr scaffolds.For a scaffold to be ideal for any tissue engineering application, the most important architectural feature of the scaffold is the interconnecting pore apertures of the pore network. A modal (Dmode) interconnected pore size of 100 µm or more is required in order for the scaffold to allow tissue ingrowth and vascularization. The 3-D µCT images of the structure of the optimized scaffolds at different NH20. The figure show that all scaffold have broad pore distribution in the range 0.003 µm – 100 µm with a Dmode at ~50 µm.Figure 4(HCO3) content.Table 4(HCO3) content. The pore size obtained from porosimetry is significantly lower than values obtained by µCT. However, one should keep in mind that the porosimetry does not provide measure of the pores but rather, the interconnected size22. In addition it is noteworthy to mention the similarities in the porosity obtained in Tables From the results, as expected, the average pore size and porosity increased as a function of NH4HCO content.g (glass transition temperature) and Tx  were recorded and are presented in Fig. x − Tg), also presented in Table 6. According to Brauer23, crystallization of bioactive glasses can be controlled by increasing the working range which is the temperature difference between crystallization and the glass transition. This stability range, ∆T, is the temperature range in which glass viscosity allows for sintering, fiber drawing, or other processing. A large temperature gap between glass transition and onset of crystallization suggests that viscous flow is more likely to occur prior to the crystallization. A small temperature gap between glass transition and onset of crystallization suggests a nucleation close to the glass transition temperature and therefore more risk of nucleation and growth of crystals during sintering, prior or during sintering. Furthermore, it is noteworthy that all glasses are expected to have a surface initiated crystallization as demonstrated for the Sr glass in ref. 8. The surface crystallization of borosilicate glasses was also evident and will be reported shortly19. It is therefore expected that with small particle size the risk of crystallization upon increasing temperature increases due to an increase in the number of nucleation sites with increasing the surface area to volume ratio25. Glass S53B50 and P40B10 have a wider processing window than glass Sr; therefore, sintering can be achieved without the glasses enduring adverse crystallization during heat treatment.All the DTA traces exhibited an endothermic event corresponding to the glass transition and an exothermic event corresponding to the crystallization of the glass. From the thermograph, TThe XRD patterns presented in Fig. SEM images of the cross section of the sintered samples revealed a dense microstructure which explains the high theoretical densities obtained between sintering temperatures of 480 °C–560 °C 2HPO as raw materials. Ca (PO3)2 and Sr (PO3)2 were used as precursors for the phosphate glasses and were prepared independently using a slow heating rate up to 900 °C.The starting materials for the borosilicate glass designated S53B50 were analytical reagent grades of Na2-26.93B2O3-22.66Na2O-1.72P2O5-21.77CaO, while glass P40B10 and Sr had a nominal composition of (50-x) P2O5-xB2O3-20CaO-20SrO-10Na2O; where x = 0 (Sr) or 10 (P40B10). Proportions of relevant oxides of the starting materials were mixed together in a platinum crucible and melted at 1250 °C for glass S53B50 and 1100 °C for glass P40B10 and Sr. The melt was poured onto a graphite mould and annealed at 40 °C below their respective glass transition temperature Tg to release internal stresses and allowed to slowly cool down to room temperature in the annealing furnace. The obtained glass ingots were then crushed using a metallic mortar and pestle for 1 hour and sieved.The three glass compositions studied are given in Table g and the onset crystallization temperature Tx of the glasses were determined using differential thermal analysis  at a heating rate of 10 °C/min for particle size of 125–250 µm. The measurements were performed on 30 mg samples in platinum pans in a N2 atmosphere. The glass transition temperature Tg was taken at the inflection point of the first endotherm, obtained by taking the first derivative of the DTA curve. The crystallization temperature Tp was found at the maximum of the exothermic peak.The glass transition temperature TThe crushed powders were charged and milled in a planetary ball mill (Fritsch Pulversette 6) using alumina balls (2 mm diameter) for 1 hour at 150 rpm, with distilled water as a grinding media. The charge to ball ratio was kept at 1:1. Dolapix C64 and PEG (polyethylene glycol) were added at 3 wt.% to the mixture as a dispersant and binder respectively. The slurries were dried in an oven at 70 °C for 24 hours. The dried powders were then sieved and a Mastersizer 2000  was used to measure the particle size distribution of the powders.4(HCO3) foaming agent. To ensure homogeneity, mixing was done in the T2F turbula mixer using 2 mm alumina balls for 30 minutes. After mixing, the resulting powders were compacted using a hydraulic press at 19.6 MPa to obtain pellets of 18.01 mm diameter and 4 mm thick.For the porous scaffolds, the glass powders were mixed with 60 vol.% and 70 vol.% NH4(HCO3) foaming agent. The samples prepared without NH4(HCO3) were sintered using a heating rate of 10 °C/min at sintering temperatures between 480 °C and 600 °C and a holding time of 2 hours. On the other hand the samples with NH4(HCO3) were sintered for 1 hour at 540 °C for S53B50 and 500 °C for P40B10 and Sr after burning off the NH4(HCO3) foaming agent at 67 °C for 2 hours. All the samples were sintered in a Muffle furnace  and cooled by switching off the furnace immediately after the sintering time was completed.Sintering of the samples was done with and without NH4(HCO3) foaming agent was determined using Archimedes principle as most of the pores are closed, whereas the density of the porous scaffolds, obtained with addition of a porogen (NH4 (HCO3)), was determined by the geometrical density (mass of the sample over its volume). The general equation used to derive the theoretical density of the sintered bodies was:The density of the samples sintered without NHθ range of 10–90°, with a step size of 0.02°. All the microstructure observations were done using scanning electron microscopy (FEI Quanta 400 FEG SEM) with attached EDS system.The sintered samples were further characterized using X-ray diffraction (D2 Phaser), with Cu Kα radiation. Diffractograms were collected over a 2Micro-computational tomography (µCT), a MicroXCT-400  was used with tube voltage 140 kV and current 71 µA. Pixel size was 5.6 µm. Porosity analysis was done with Fiji using BoneJ plugin. µCT visualizations were done with Avizo 9.1 .Mercury Intrusion Porosimetry  and micro computational tomography (µCT) were performed to determine the porosity and the pore size distribution of the scaffolds. The mercury was intruded using a pressure from 0.10 to 60 000 psia at an equilibration time of 10 seconds using an evacuation pressure and time of 50 µmHg and 30 minutes, respectively.


The title compound is isostructural with CuMg2 (orthorhombic Fddd symmetry). Ti atoms are in the square antiprisms of Bi atoms. The network of one type of Bi atom spirals along the a-axis direction while honeycomb layers of the other type of Bi atom spreading inn the ab plane interlace one another.Black granular single crystals of monotitanium dibismuth, TiBi 2, were synthesized by slow cooling of a mixture of Bi and Ti from 693 K. The title compound is isostructural with CuMg2 (orthorhombic Fddd symmetry). Ti atoms are located in square antiprisms of Bi atoms. The network of one type of Bi atom spirals along the a-axis direction while honeycomb layers of the other type of Bi atom spreading in the ab plane interlace one another.Black granular single crystals of monotitanium dibismuth, TiBi The Bi2—Bi2 bond lengths in the Bi2 honeycomb layers in the ab plane are 3.4639 (8) Å in the b-axis direction and 3.3435 (4) Å in the other direction. The Bi—Bi bond lengths in the spiral rings and honeycomb layers in TiBi2 are in the range of those in Bi metal  Å in the 2 and H2O < 1 p.p.m.). The pellet was put in a tantalum boat . The boat was sealed in a stainless-steel (SUS 316) tube. The sample was heated to 693 K in an electric furnace with a heating rate of 3.5 K min−1. This temperature was kept for 10 h, and then lowered to 473 K with a cooling rate of 5 K h−1. After cooling to room temperature by shutting off the electrical power to the furnace, the stainless-steel tube was cut and opened in the glove box. To identify the crystalline phases, powder XRD  was carried out for a portion of the sample which was ground in the alumina mortar and sealed under an Ar atmosphere in a holder with a kapton film window. The chemical compositions of TiBi2 single crystals placed on a carbon tape were determined with an electron probe microanalyzer . Bi and TiO2  were used as standard samples. The analyzed composition ratio of Ti:Bi in the crystals was 1.0 (1):2.0 (1). A single crystal of TiBi2 was sealed in a glass capillary with Ar gas in the glove box for the single-crystal XRD experiment.Starting powders of Bi  and Ti  were weighed, mixed in an alumina mortar with a pestle and formed into a pellet by uniaxial pressing in an Ar gas-filled glove box  I. DOI: 10.1107/S2056989016012391/br2262Isup2.hklStructure factors: contains datablock(s) I. DOI: 1497032CCDC reference: crystallographic information; 3D view; checkCIF reportAdditional supporting information:


The concept of coding metasurface makes a link between physically metamaterial particles and digital codes, and hence it is possible to perform digital signal processing on the coding metasurface to realize unusual physical phenomena. Here, this study presents to perform Fourier operations on coding metasurfaces and proposes a principle called as scattering‐pattern shift using the convolution theorem, which allows steering of the scattering pattern to an arbitrarily predesigned direction. Owing to the constant reflection amplitude of coding particles, the required coding pattern can be simply achieved by the modulus of two coding matrices. This study demonstrates that the scattering patterns that are directly calculated from the coding pattern using the Fourier transform have excellent agreements to the numerical simulations based on realistic coding structures, providing an efficient method in optimizing coding patterns to achieve predesigned scattering beams. The most important advantage of this approach over the previous schemes in producing anomalous single‐beam scattering is its flexible and continuous controls to arbitrary directions. This work opens a new route to study metamaterial from a fully digital perspective, predicting the possibility of combining conventional theorems in digital signal processing with the coding metasurface to realize more powerful manipulations of electromagnetic waves. The proposed principle and method can make flexible and continuous manipulations to scattering beams (or patterns) of EM waves using the coding metasurfaces. For the particular design in this article, we can realize a single scattering beam and steer it to an arbitrarily pre‐designed direction with negligible distortion to the shape of coding pattern. We further show that this idea can be easily implemented with coding metasurface by calculating the modulus of the original coding sequence and a gradient coding sequence. The flexible and continuous controls of the far‐field EM waves by the proposed principle have been demonstrated theoretically and numerically with several examples, and verified experimentally by four different samples fabricated at terahertz frequencies.2E represents the scattered electric field in the far‐field region at distance r, elevation angle θ, and azimuth angle ϕ in the spherical coordinate; k is the wavenumber in free space; and P is the 2D Fourier transform of tangential electric field E on the coding metasurface u, v are the angular coordinates. In the product item Np, N is the number of coding particles along the x and y directions, and p is the side‐length of the coding particle. The scattering pattern can be expressed by the coordinates  by making a coordinate transformation from  to Before introducing the principle of scattering‐pattern shift, we note that the scattering pattern can be analytically calculated by the Fourier transform once the coding pattern on a coding metasurface is given  We know that the Fourier transform decomposes a function of time  into the frequencies that make it up, i.e., the frequency domain representation of the original signal. In this regard, Equation t and ω in Equation xλ and sinθ, respectively, giving the following equation xλ=x/λ is the electrical length, and θ is the angle with respect to the normal direction. Note that the above equation cannot be directly applied to the design of coding metasurface because the coding digits will not be preserved after the operation of convolution, i.e., the reflection amplitudes of all coding particles are not always be equal. Fortunately, Equation g(ω) becomes a Dirac‐delta function ejω0t is the time‐shift item in the time domain and the impulse function δ(ω0) is its frequency spectrum expression in the frequency domain. Equation f(ω) with an impulse function δ(ω−ω0) will shift the spectrum function f(ω) by ω0 in the frequency domain without distortion. Applying the same argument substitutions to Equation ejxλsinθ0 describes the electric field distribution with unity amplitude and gradient phase along a certain direction, which can be simply implemented by the coding metasurface. The principle of scattering‐pattern shift mathematically defined in Equation E(xλ) by a gradient coding sequence ejxλsinθ0 leads to a deviation of the scattering pattern E(sinθ) away from its original direction by the quantity sinθ0 in the angular coordinate. It is interesting to note that the multiplication of the phases of two coding patterns is just equivalent to the modulus of their coding digits, providing much reduced computation complexity for the optimization of scattering patterns.Owing to the fact that the electric field distribution on the coding metasurface and the scattering pattern in the far‐field region are a Fourier transform pair, we could therefore replace the arguments FigureWe take a 2‐bit coding metasurface as a proof of principle to demonstrate how the above concept is used to control the direction of scattering pattern. δ(ω−ω0) in Figure 0, as shown in Figure To better understand the process of scattering‐pattern shift, we give the corresponding frequency spectra, in which the coding patterns are considered as signals in time domain and the scattering patterns are assumed as their corresponding frequency spectra. From Figure Figureθ from 0° to 90° and ϕ from −180° to 180°, as indicated by the red beam. Here, an example is given to demonstrate how the arbitrary direction is realized from two different coding sequences S1 (0 0 1 1 2 2 3 3 0 0 1 1 2 2 3 3…) and S2 (3 3 3 2 2 2 1 1 1 0 0 0 3 3 3 2 2 2 1 1 1 0 0 0…), each of which generates a single‐beam scattering pointing in a certain direction. For simplicity, the 2‐bit digits “0,” “1,” “2,” and “3” stand for “00,” “01,” “10,” and “11,” respectively. According to the principle of scattering‐pattern shift, the required coding sequence can be calculated by the modulus of them as S3 (3 3 0 3 0 0 0 0 1 0 1 1 1 1 2 1 2 2 2 2 3 2 3 3…), which produces a single‐beam pointing in a new direction. Because the added sequence S2 is longer in periodicity and with decreasing order, the anomalous scattering angle enabled by the combined sequence S3 should be smaller than that from S1, as will be discussed in details in the following section.3d = 25 μm and period length p = 70 μm. The octagon‐shaped pattern is characterized by side length an, with the subscript representing the value of coding digits. For coding particle “00,” the longer side length of the octagon coincides with the edge of the substrate (a0 = 44 μm). Coding particles “01,” “10,” and “11” are obtained by scaling down the coding particle “00” with ratios 0.844, 0.725, and 0.45 , respectively. The polyimide is modeled as a dielectric with permittivity ε = 3.0 + i0.09. The commercial software, CST Microwave Studio, is used to simulate the reflection phases and amplitudes of the four coding particles, which are shown in Figure To validate the principle of the scattering‐pattern shift with realistic materials and structures, we design an octagon‐shaped coding particle at the terahertz frequency, as shown in Figure Figure1M as1M are given in Figure θ and azimuthal angle ϕ, as illustrated in Figure x–z plane with respect to the z‐axis. To better visualize the scattering angle, Figure To demonstrate the performance of the proposed idea, we give two examples encoded with different coding sequences, as shown in 1M, their modulus gives the mixed coding pattern shown in Figure z‐axis is exactly equal to the anomalous scattering angle generated by the gradient coding sequence (see Supporting Information Note S3) λ and Γ represent the free‐space wavelength and the periodicity of the gradient coding sequence, respectively. Substituting Γ = 840 μm and λ = 300 μm into Equation θ and ϕ) but the angular components in Equation θ and sinθ, the scattering pattern should, in theory, experiences slight distortion in some extent in this process, especially for large scattering angles. In practical applications, however, the distortion could be neglected due to the approximate linearity between θ and sinθ for smaller θ values (≤30°).If a gradient coding sequence “0 1 2 3 0 1 2 3 …”  is added to coding matrix 2Mx‐ and y‐directions, the normally incident wave will be deflected to four directions in the upper‐half space with equal angles θ with respect to the z‐axis, as observed from the 3D scattering pattern in Figure θ for the chessboard distribution can be predicted by (see Supporting Information Note S3)The next example is given to evaluate the performance of scattering‐pattern shift in controlling multiple beams. The chessboard coding pattern, as shown in Figure Γ = 840 μm and λ = 300 μm into Equation θ is calculated as 22.3°, which is larger than that of the 1M case. Figure z‐axis by 20.9°. Again, little distortion can be found in the 2D scattering pattern in Figure Substituting To numerically validate the proposed principle, all coding metasurfaces presented in Figure n equals 2, 3, and 4, respectively. As a result, the anomalous reflection angle cannot be arbitrarily designed. For the case when n = 1, the length of gradient coding sequence (280 μm) is smaller than the free‐space wavelength (300 μm), in which condition the normally incident wave will not be reflected to space but is converted to the surface wave propagating on the metasurface.When the coding metamaterial was first proposed in ref.,Figurez‐axis) in the x–z plane, as shown in the 3D/2D scattering patterns in Figure Here, we illustrate how the principle of scattering‐pattern shift is used to overcome the above shortcoming and design coding patterns to generate a single beam with arbitrarily scattering angle. θ1 and θ2 are the anomalous scattering angles corresponding to the two gradient coding sequences that are added or subtracted. To clearly visualize how dense the scattering angle can be realized with this method using the 2‐bit coding metasurface, we calculate the angle θ from Equation FigureM and N of each coding digit in the gradient coding sequence “0 1 2 3…,” respectively. For instance, the coding sequence becomes “0 0 1 1 2 2 3 3…” and “0 0 0 1 1 1 2 2 2 3 3 3…” if M = 2 and N = 3. The minus sign of M or N indicates the case when the coding sequence is reversed. From Figure M and N are opposite to each other. The scattering angle in the region far from the center is almost below 10° due to the large periodicity of gradient coding sequence. For the current scheme that only two coding sequences are added together, the attainable scattering angles are still not quite densely distributed in the range from 60° to 90°. Fortunately, the density in those directions and the entire upper‐half space can be increased by adding three or multiple coding sequences with different repetition numbers. In the limit of infinitely large number of items being added, the scattering angle can be continuously obtained from 0° to 90°.Numerical simulations of structured coding metasurfaces have also been conducted to verify the above theoretical results, as presented in Figure S4 (Supporting Information), in which little discrepancy is observed between the numerical and theoretical results. Supporting Information Figure S5 provides a detailed discussion on the conversion efficiency from the normally incidence to the anomalously scattering beam. We notice that the scattering angles 63.2° and 10.3° are not directly calculated from the addition and subtraction of the scattering angles 32.4° and 20.9°. According to Equation θ and ϕ can be calculated as θ1 and θ2 are the elevation angles of the two coding sequences grading along the x‐ and y‐directions. An example is given in Supporting Information Figure S4e to demonstrate the rotation of the beam pattern in the azimuthal direction.The above method allows the scattering beam to scan in the elevation plane. However, in many applications, the beam is required to scan in azimuthal directions, which can be realized by adding a coding sequence grading along the orthogonal direction. Once the anomalous reflection angles generated by two orthogonal gradient coding sequences are given, the new angles θ,ϕ) by the modulus of two gradient coding sequences with different repetition numbers  and orthogonal directions  are plotted in Figure θ is close to 0° and 90°, can be improved by increasing the number of coding sequences being added.Based on Equations 4Figure2, P2+P8, P2+P4, and P2+P3, respectively, in which Pn represents a gradient coding sequence “0 1 2 3 0 1 2 3…” with the repetition number n. For example, P2 is “0 0 1 1 2 2 3 3 0 0 1 1 2 2 3 3….” Each sample includes 220 × 220 coding particles, covering an area of 15.4 × 15.4 mm2. The microscopy image  of the sample is shown in Figure To experimentally verify the principle of scattering‐pattern shift at the terahertz frequency, four different samples of coding metasurfaces . When P2 is added with another gradient coding sequence P8, it generates a single beam in the directions from 44° to 56°, as observed in Figure 4 and P3 to the original coding sequence P2, resulting in the scattering peaks appearing at larger ranges of angles from 58° to 68°  as 62%, 61%, 50%, and 40%, respectively. We found that the measured efficiencies decrease with the increasing variation rate of gradient coding sequence. Such a phenomenon can also be observed in the numerical simulations in Figure S5 (Supporting Information), in which the efficiencies are lower for the mixed coding sequences , especially for larger reflection angles . This could be attributed to the following two reasons. First, the periodicity of the mixed coding sequence is longer than those of two constitutive coding sequences. In this case, the periodicities for cases a–d are 8, 12, 24, and 24, respectively, as can be observed from the coding patterns shown in Figure S4(i) (Supporting Information). Therefore, fewer repetitions of the coding sequence will be illuminated by the normal incidence of terahertz waves, leading to the appearances of scattering in other directions. It can be better understood by making an analogy to the Fourier transform in signal processing. A finite‐length sinusoidal signal with lower frequency, i.e., fewer complete sinusoidal waveforms, will have more frequency components in spectrum than the sinusoidal signal of the same length with higher frequency. Second, the momentum matching between the normally incident wave and the obliquely scattered wave becomes worse as the oblique angle increases. Such a momentum mismatch will be much more severe when the anomalous reflection angle approaches 90°, in which circumstance the normally incident beam will be partially converted to surface wave.5To summarize, we have proposed a general method to control the scattering of EM waves flexibly and continuously by performing Fourier operations on coding metasurfaces. As a specific operation with convolution, we proposed the principle of scattering‐pattern shift to steer the scattering pattern of a coding metasurface to an arbitrarily predesigned direction. Such a principle to design coding metasurface is inspired by the frequency‐shift property in the conventional Fourier transform theory, and is simply realized by calculating the modulus of the original coding pattern and a gradient coding sequence. This method allows us to rotate the scattering pattern by a certain angle in the 3D space with negligible distortion. One of the most significant contributions of this work is providing a method to realize arbitrary radiation angles based on the 2‐bit coding metasurface which has only four different coding digits. This has overcome the shortcomings of the previous coding scheme,Four coding metasurface samples have been fabricated and measured in the terahertz band to verify the performance of single‐beam scattering to an arbitrary direction. The experimental results show that the normally incident terahertz wave could be deflected to an angle as large as 72° with 40% efficiency, which is significantly better than the previously reported results realized by the conventional reflectarray even at microwave frequency.We remark that the method proposed in this work is not limited to the terahertz band, but can be easily extended to the microwave and optical frequencies. Further studies will focus on the implementation of programmable anisotropic metasurfaces using active elements, such as varactor diodes6Sample Fabrication: The fabrication process mainly included the preparation of a polyimide layer and the conventional photolithography. First, a 180 nm thick gold layer was e‐beam‐evaporated on a 2 in. silicon wafer  to serve as the metallic background. Then, a 25 μm thick polyimide layer was coated on the gold layer and baked on a hot plate at 80, 120, 180, and 250 °C for 5, 5, 5, and 20 min, respectively. Since the liquid polyimide chosen  could only be used to form a maximum thickness of 10 μm at the minimum spin rate of 1150 rpm, the above spin‐coating and curing processes were repeated twice for the final completion of the 25 μm thick polyimide layer. Finally, followed by the standard photolithography, another Ti/Au layer (10/180 nm) was deposited on the patterned photoresist by electron‐beam evaporation. The final metallic pattern was fabricated by a liftoff process in acetone.Measurement Systems: The reflection spectra of the fabricated samples with a broadband (0.3–3.0 THz) 4‐f fiber‐based rotary THz‐TDS were measured, as schematically illustrated in Figure As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re‐organized for online delivery, but are not copy‐edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors.SupplementaryClick here for additional data file.


We conducted the first study in Australia to measure NH3 dry deposition within 1 km of a commercial beef cattle feedlot in Victoria. NH3 concentrations and deposition fluxes decreased exponentially with distance away from the feedlot. The mean NH3 concentrations decreased from 419 μg N m−3 at 50 m to 36 μg N m−3 at 1 km, while the mean NH3 dry deposition fluxes decreased from 2.38 μg N m−2 s−1 at 50 m to 0.20 μg N m−2 s−1 at 1 km downwind from the feedlot. These results extrapolate to NH3 deposition of 53.9 tonne N yr−1 in the area within 1 km from the feedlot, or 67.5 kg N ha−1 yr−1 as an area-weighted mean, accounting for 8.1% of the annual NH3-N emissions from the feedlot. Thus NH3 deposition around feedlots is a significant nitrogen input for surrounding ecosystems. Researches need be conducted to evaluate the impacts of NH3 deposition on the surrounding natural or semi-naturals ecosystems and to reduce N fertilizer application rate for the surrounding crops by considering nitrogen input from NH3 deposition.Intensive cattle feedlots are large emission sources of ammonia (NH Once emitted into the atmosphere, part of it can be removed through dry deposition over the areas near the emission source13 can react with acidic gases such as H2SO4 and HNO3 to form secondary aerosols, including (NH4)2SO4, NH4HSO4 and NH4NO3, which are the major contributors to fine particulate matter23 and its secondary aerosols can result in increased nitrogen (N) input to the natural or semi-natural ecosystems and subsequently eutrophicationAmmonia NH is the p3 is emitted mainly from anthropogenic sources3 in many developed countries110113 deposition near hotspots such as animal farms. For example, Fowler et al.3 deposition around an intensive poultry farm. They found that the deposition rate decreased from 42 to 5 kg N ha−1 yr−1 as the distance of the monitoring sites from the farm increased from 15 m to 270 m. They also found that the NH3 adsorbed by woodlands within 270 m and 1 km from the source accounted for 3.2% and 10% of the annual emissions from the farm, respectively. Walker et al.3 dry deposition rates increased from 16 kg N ha−1 yr−1 at 500 m to 145 kg N ha−1 yr−1 at 10 m from a commercial swine production facility. The accumulated NH3 dry deposition over the nearest 500 m from the barn/lagoon complex accounted for 10.4% of annual emissionset al.3 deposition downwind of a large cattle feedlot in Canada and found that NH3 deposition ranged from 104 kg N ha−1 yr−1 at the feedlot boundary to 49 kg N ha−1 yr−1 700 m from the source.Atmospheric NH3 hotspots in Australia163-N based on an emission rate of 104 g NH3-N head−1 d−1 and 875,000 beef cattle in Australian feedlots3 surrounding these hotspots. We conducted a field study with the aim of quantifying NH3 dry deposition within 1 km of the edge of a commercial feedlot in Victoria, Australia from April to June 2015. We measured NH3 concentrations at five locations along a transect downwind within 1 km of the feedlot and calculated NH3 deposition fluxes using a well tested bi-directional NH3 exchange model with empirical parameters.Cattle feedlots are large NH−1 respectively. The averaged wind speed during the three periods (3.0 m s−1) was comparable to the annual mean wind speed in 2015 (3.0 m s−1)The dynamics of hourly air temperature, relative humidity and wind speed during the three sampling periods in April, May and June are shown in 3 concentrations showed large spatial and temporal variation  and caused higher deposition flux in the daytime3 concentration during the nighttime than during the daytime at 200 m, 500 m and 1000 m sites made NH3 concentration the major factor affecting NH3 deposition flux.The NHriations , ranging0 m site  and ther3 fluxes in the three sampling periods in April, May and June under the land use types of cropland, grassland and pasture are summarized in 3 concentration, the mean NH3 flux also decreased exponentially with the distance away from the feedlot. The variation of the mean NH3 deposition fluxes among the three land use types was small. The similarity may be ascribed to the small differences of input parameters , stomatal resistance (Rs), cuticular resistance (Rw)) that were used for calculating NH3 bi-directional exchanges for the three land use types2122The mean NH3 dry deposition rates at the downwind sites by assuming that the mean NH3 deposition fluxes during April - June for cropland, grassland and pasture represented the annual average of NH3 deposition fluxes. The estimated annual NH3 deposition rates were 614, 496, 322, 210 and 106 kg N ha−1 yr−1 at the downwind sites with 50, 100, 200, 500 and 1000 m respectively, from the feedlot, provided that wind direction was constant. In fact, NH3 deposition mostly occurred in the downwind areas of the feedlot in this study since the NH3 concentration was very low or could not be detected in the upwind direction. Due to the frequent changes in wind direction in the studied region, we calculated the annual NH3 deposition in the downwind areas of eight major wind directions . This was comparable to that reported by Fowler et al.3 emissions were dry deposited within 1 km of a poultry farm. However, some other studies reported higher fractions of emissions deposited locally. For example, Hao et al.3 emitted from a 25,000-head cattle feedlot was deposited to the soil within 1 km of the feedlot. Similarly, Walker et al.3 was dry deposited within 500 m of the emission source. Modelling results have shown that the fraction of local deposited NH3 emissions ranged from 2% to 55% within 1 km of the source, which mainly depending on source height, wind speed, atmospheric stability, structure of the surrounding canopies and surface resistance1−1 at 2 m height). High wind speed usually favors a high NH3 emission rate3 plume and thus cause low NH3 concentration as well as low NH3 dry deposition in the downwind areas3 deposition in the downwind areas and the increased NH3 emission rate from feedlot due to high wind speed then may have resulted in a relatively low fraction of locally deposited emissions.The estimated total annual NH3 emitted from the studied feedlot, one possible fate may be that it was transported to the mixing layer in the downwind regions of the feedlot by turbulent dispersion and advection. The depth of the mixing layer has been reported to range from 100 m to up to 1500 m25253 concentration around the same feedlot as this study, using the airborne technology, found NH3 concentration to range from 470 ppb (294 μg N m−3) at 0.5 km downwind of the feedlot to 25 ppb (16 μg N m−3) at 6.5 km downwind of the feedlot at 35 m above ground, and as high as 40 ppb (25 μg N m−3) at 310 m above the ground along the boundary of the feedlot3 may be transported to the mixing layer and could be transported at least 6.5 km from the feedlot. Due to the small emission intensities of acidic gases  from industrial and transport sources and nearly no aerosol pollution in the region of the feedlot, the transformation of NH3 to particulate NH4+ could be ignored in the neighbourhood of the feedlot. Therefore, it is also worthwhile to further investigate NH3 deposition and related environmental effects in the downwind areas 6.5 km or more from intensive feedlots.For the remaining 92% of the NH3 concentrations and estimated NH3 deposition rates 1 km from the cattle feedlot in this study were higher than those reported from poultry farm or swine production facilities133 concentration was 19 to 52 μg N m−3 at a distance of 15 m from a poultry farm (emission intensity: 4.8 tonne NH3-N yr−1) in the UK and declined to background concentrations of 0.8 to 1.6 μg N m−3 at a distance of 270 m, while NH3 deposition decreased from 42 kg N ha−1 yr−1 at 15 m to 5 kg N ha−1 yr−1 at 270 m with an average of 7 kg N ha−1 yr−1 in the area within 300 m of the poultry farm3 concentration ranged from 139 μg N m−3 at a distance of 10 m from a swine production facility in eastern North Carolina (emission intensity: 28.2 tonne NH3-N yr−1) to 10.7 μg N m−3 at 698 m, while the mean NH3 deposition ranged from 26 to 52 kg N ha−1 yr−1 within 500 m from the source3 emission intensity of the source in this study  was also higher than those in the above two studies, it can be concluded that the sources with high NH3 emission intensities will lead to high NH3 deposition in the surrounding area. This conclusion is also supported by Hao et al.3 deposition around a 25,000-head beef feedlot (emission intensity: 235 tonne NH3-N yr−1) in Alberta, Canada, which ranged from 120 kg N ha−1 yr−1 50 m from the source to 20.8 kg N ha−1 yr−1 1 km from the feedlot.The measured NH3 exchange model to estimate NH3 deposition near a feedlot in Australia. Our calculated NH3 deposition is still subject to uncertainty in the model input parameters 28−1)−1)3 deposition fluxes in this study are still in a reasonable range. Due to the difficulty in accessing the cropland to install the NH3 samplers in the growing season, we only conducted NH3 deposition sampling during three months. Underestimation may exist when using these three months data to estimate NH3 deposition for the whole year. Firstly, due to that the mean air temperature during the three sampling periods in the study was 4 °C lower than the annual mean of air temperature and NH3 emission rate is positively correlated with air temperature3 emission intensity and thus the measured NH3 concentration during the sampling periods may be lower than the annual means, which means the annual NH3 deposition rate at the sampling sites might be underestimated. Secondly, during the three months of sampling periods, only one month was classified into growing season and the other two months classified into un-growing season. In fact, there are half growing season and half un-growing season in a year in the studied region. Because the Rs and Rw are smaller in growing season than those in un-growing season, which favors faster deposition of NH3 in growing season than those in un-growing season, the reduced duration of growing season (by 17%) in a year may cause another underestimate of the annual NH3 deposition rates.It should be noted that the study we report here is a pilot study to apply the bi-directional NH3 deposition around intensive feedlots or animal farms, which was ranged from 20 to 120 kg N ha−1 yr−1 and usually higher than the critical loads (10–15 kg N ha−1 yr−1) of N deposition for most natural or semi-natural ecosystems2O emissions could occur in natural and semi-natural ecosystems with increased atmospheric N deposition6783 deposition around the feedlots or animal facilities, comprehensive studies should be conducted to evaluate the impacts of NH3 deposition on the surrounding natural or semi-natural ecosystems, especially in those regions already suffering from high background N deposition  and grass hay−1) and sown in June and harvested in October or November, and fallowed from November or December until May in the following year. The plants in the pasture and grassland were usually growing during June to September.The experiment was conducted at a typical intensive cattle feedlot, in northeastern Victoria, Australia . The reg3 deposition measurement was conducted during three sampling periods in 2015 . The NH3 concentration was measured by a denuder system for long-term ammonia sampling (DELTA)3435−1. Prior to the measurement, two denuders, connected in series to adsorb the NH3 in the air, were treated with a solution of 5% (m/v) citric acid in methanol. When the air was drawn through the denuder train, NH3 gas was adsorbed to the inner surface of the denuders. The total sampled air volume was recorded by a dry gas meter . The gas meter was checked at the start of each sampling period using a gas flow meter to ensure that the recorded gas volumes were correct. The denuders, gas meter and pump were connected in sequence with short (2–3 cm) silicone tubes, and were fixed in a PVC box (40 × 30 × 50 cm) with the inlet of the denuder train exposed to the ambient air. During NH3 sampling period, the PVC box was attached to a pole at a height of 1.5 m above the ground. The denuder trains were changed two times each day, based on the day and night cycle. During each sampling period, five daytime (8:00 am to 5:00 pm) and nighttime (6:00 pm to 7:00 am in the following day) NH3 samples were collected continuously at each location. The samples were stored at 4 °C and analysed at the end of each sampling period at an off-site laboratory. The NH3 denuders were extracted with milliQ® water for 1 h, and the extraction was analysed for NH4+-N content by segmented flow analyzer . The detection limit of the DELTA system, calculated as 2σ (two times of the standard deviation) of the field blanks, was 0.28 μg N m−3.The NH3 concentrations were measured at five locations downwind of the feedlot. The sampling locations were selected along a transect downwind of the centre of the feedlot, with a distance of 50, 100, 200, 500 and 1000 m from the fence line of the feedlot  was set up at a height of 3.3 m above the ground located to the east of the feedlot. Fifteen-min averaged air temperature, wind speed, friction velocity, Monin-Obuhkov length and relative humidity were recorded at 10 Hz. The raw data was processed to hourly average data using SAS software .3 exchange model, which is called the two-layer canopy compensation point model233 dry deposition around the feedlot. Similar to most of the dry deposition models, the bi-directional flux model is based on a formula analogous to Ohm’s law in electrical circuits where flux  is calculated by dividing the concentration difference  by the deposition resistance 21et al.3 flux (Ft) is the sum of bi-directional exchange with the leaf stomata (Fs), deposition to the leaf cuticle (Fw) and bi-directional exchange with ground (Fg). Among these pathways, Fs and Fw occur parallelly in the canopy layer and can be summed as the canopy flux (Ff), while Fg occurs in the ground layerA well tested bi-directional NH3 concentration at the height of 1.5 m above the ground level, 3 concentration at height of d + z0, d is the zero-plane displacement height, z0 is the surface roughness length, Ra is the aerodynamic resistance, a function of the vertical turbulent diffusive transport through the atmosphere, 3 compensation point, Rb the quasi laminar boundary layer resistance, Rs the stomatal resistance, Rw the cuticular resistance, 3 compensation point and Rg the in-canopy resistance to the ground. Based on the equations of (1), (3), (4) and (7), where Based on the equations of (2), (4), (5), (6) and (8), the equation of Ra, Rb, Rg, Rs, Rw, et al.3 dry deposition flux was calculated. Hourly NH3 dry deposition flux was calculated based on the hourly meteorological data. As we did not measure hourly NH3 concentrations, their values in a sampling event were assumed to be equal to the corresponding daytime or nighttime NH3 concentration measured by the DELTA system. The missing data of NH3 concentrations in a sampling event were interpolated with the mean daytime or nighttime NH3 concentrations measured during the same sampling period. The R software v3.13The parameters of 3 dry deposition rates in the downwind transect to the total NH3 deposition in the downwind area within 1 km from the feedlot. Firstly, using the correlation between the measured NH3 deposition rate and distance from the feedlot, we estimated the deposition rates at 200, 300, 400, 600, 700, 800 and 900 m from the feedlot. Secondly, due to that NH3 deposition occurred mostly in the downwind direction as the NH3 concentration was very low or could not be detected, we divided the total area within 1 km from the feedlot into eight downwind areas based on the eight major wind directions. Here a downwind area is defined as the area within 1 km from the feedlot that can be affected by the feedlot NH3 plumes transported by a certain direction of wind. Examples for dividing downwind areas are shown in 3 deposition rate in this area was equal to the NH3 deposition rate at 50 m from the feedlot. NH3 deposition rates in other sub-areas were assumed to be equal to the mean of the deposition rates at the nearest and longest distances from the feedlot in the specified sub-area. For example, for sub-area 2), the NH3 deposition rate in the area was assumed to be equal to the mean of the deposition rates at 50 m and 100 m from the feedlot. The NH3 deposition rate in each sub-area then can be calculated by multiplying the site-specific NH3 deposition rate with the size of each sub-area. Thirdly, we calculated NH3 deposition in a downwind area by multiplying the frequency of a wind direction in a year with the summed NH3 deposition in 11 sub-areas of this downwind area. By summation, we can get the total NH3 deposition within 1 km from the feedlot using the following equation:The following steps were used to integrate the site-specific NHTD is the total NH3 deposition (tonne N yr−1) in the area within 1 km from the feedlot, Aij is the size (ha) of the jth sub-area of the ith downwind area, Dj the NH3 deposition rate (kg N ha−1 yr−1) in the jth sub-area, fi is the frequency of the ith wind direction in a year and and 1000 the unit conversion factor. The area-weighted NH3 deposition rate is then calculated by divided the total NH3 dry deposition around the feedlot by the total area within 1 km from the feedlot.where How to cite this article: Shen, J. et al. Ammonia deposition in the neighbourhood of an intensive cattle feedlot in Victoria, Australia. Sci. Rep.6, 32793; doi: 10.1038/srep32793 (2016).


II and BiIII chlorometalate salts in the choline chloride/ethylene glycol (1:2 molar ratio) deep eutectic solvent was studied on glassy carbon and gold by cyclic voltammetry, rotating disc voltammetry, and chronoamperometry. The SnII‐containing electrolyte showed one voltammetric redox process corresponding to SnII/Sn0. The diffusion coefficient of [SnCl3]−, detected as the dominating species by Raman spectroscopy, was determined from Levich and Cottrell analyses. The BiIII‐containing electrolyte showed two voltammetric reduction processes, both attributed to BiIII/Bi0. Dimensionless current/time transients revealed that the electrodeposition of both Sn and Bi on glassy carbon proceeded by 3D‐progressive nucleation at a low overpotential and changed to instantaneous at higher overpotentials. The nucleation rate of Bi on glassy carbon was considerably smaller than that of Sn. Elemental Sn and Bi were electrodeposited on Au‐coated glass slides from their respective salt solutions, as were Sn–Bi alloys from a 2:1 SnII/BiIII solution. The biphasic Sn–Bi alloys changed from a Bi‐rich composition to a Sn‐rich composition by making the deposition potential more negative.The electrodeposition of tin, bismuth, and tin–bismuth alloys from Sn Electrodeposition of tin from choline chloride based type 3 deep eutectic solvents containing either anhydrous SnCl22⋅2 H2O3]−, but this method is not conclusive, because of possible fragmentation in the gas phase. Raman spectroscopy of strongly Lewis basic imidazolium chloride based ionic liquids showed [SnCl3]− to be the dominating SnII species.The electrodeposition of Sn from the type 1III in chloride‐containing aqueousIn contrast to tin, the electrochemistry of bismuth in deep eutectic solvents is less explored. The speciation of Bi3/N‐(n‐butyl)pyridinium chloride containing 1 mm BiCl3.III was shown to proceed via the low‐valence state intermediate Bi53+. Furthermore, evidence for the formation of BiI[31] during the anodic oxidation of Bi was presented.2O3 was studied,III in these DESs is unclear. Recently, the electrodeposition of Sn–Bi coatings on Cu from a DES comprising a 1:2 molar ratio of choline chloride/ethylene glycol (12CE) containing 0.05 m SnCl2, 0.05 m BiCl3, and 0.1 m H3BO4 as an additive was also reported,The electrochemistry of bismuth was previously studied in a Lewis acidic type 1 deep eutectic electrolyte of AlClHerein, we describe the electrodeposition of Sn, Bi, and their alloys from their corresponding tetrabutylammonium chlorometalate salts in 12CE and characterization of the metallic deposits.22.1−1 of [NnBu4][SnCl3] and [NnBu4][BiCl4] on a glassy carbon (GC) electrode are shown in Figure The cyclic voltammetry (CV) curves of 12CE solutions containing 10 mmol LEpred) for SnII on GC at −0.571 V, followed by an oxidation peak potential (Epox) at −0.322 V with a typical symmetrical shape for metal stripping in the anodic return sweep. At a potential of around +0.7 V, SnII species are irreversibly oxidized to SnIV . On the basis of the ratio of the anodic/cathodic charge, the coulombic efficiency for the SnII/0 reduction of all three cycles is around 92 %, if complete anodic stripping of Sn is assumed. This value is considerably higher than the 70 % efficiency for the electrodeposition of tin from the same tin salt on gold in a CH2F2 supercritical fluid.The CV curve in Figure III, two reduction peaks are observed at −0.300 and −0.923 V, and this is followed by a single oxidation/stripping peak at +0.019 V . Hence, blocking effects such as those reported during the electrodeposition of zinc from the same electrolyte can be dismissed in the potential range of −1.5 to +1.0 V versus Ag wire used here for Sn and Bi.Whereas blocking of the glassy carbon surface by an adsorbed layer of choline ions was reported to play a role in the electrodeposition of zinc,The speciation of the chlorometalates in the 12CE electrolyte was investigated by Raman spectroscopy. The Raman spectra show bands corresponding to vibrations of Bi−Cl  and the band observed is weak. Using higher BiIII concentrations is constrained by the low solubility of the salt. On the basis of the Raman data alone, the presence of a second bismuth species can thus not be completely ruled out.The Raman spectrum of 12CE containing Cl as the supporting electrolyte. On the basis of the Raman data and by comparison of the relative reduction potentials, it seems most likely that the first reduction peak (Epred=−0.30 V) is associated with reduction of the more dominant (≈90 %) [BiCl6]3− anion. The second reduction (−0.92 V) also produces elemental Bi. However, the nature of the bismuth species giving rise to this reduction wave is not easy to establish given the propensity of bismuth(III) ions to form halide‐bridged dimers and higher oligomers and the variable (high) coordination numbers that BiIII may adopt.2Cl11]5− and [Bi2Cl10]4− dimers are likely candidates, because they bear higher negative charges and have a chloride/bismuth ratio similar to that of [BiCl6]3−. Also, the possibility of ethylene glycol taking part in the coordinationThe relative reduction potentials of the chlorometalates determined for Bi/Bi/SnII −0.19 V in 1119Sn NMR and 1H NMR spectroscopy in 1‐butyl‐3‐methylimidazolium chloride (C4mimCl) solutions containing cis‐[Pt(PPh3)2Cl2] and different molar fractions of SnCl2 (χSnCl2). The authors observed a decrease in the 119Sn chemical shift upon decreasing χSnCl2and suggested the formation of [SnCl4]2− anions in Lewis basic media. At χSnCl2<0.5, the NMR spectra only showed a single 119Sn resonance, which indicated that only a single chlorostannate species was present in the Lewis basic solution.Illner et al.119Sn NMR spectroscopy, Raman spectroscopy, and differential scanning calorimetric studies of different molar fractions of SnCl2 in 1‐octyl‐3‐methylimidazolium (C8mim) and 1‐ethyl‐3‐methylimidazolium (C2mim) solutions showed Cl− and [SnCl3]− to be the only significant anions present in the Lewis basic medium. It was concluded that no [SnCl4]2− was present under these conditions.The anionic speciation of chlorostannates(II) in ionic liquids was systematically investigated by Currie et al.3]− in 12CE electrolyte.119Sn NMR spectroscopy of a 10 mmol L−1 solution of [NnBu4][SnCl3] in 12CE  revealed a sharp resonance at δ=−160.7 ppm. This value is similar to the chemical shifts previously reported for Lewis basic imidazolium‐based ionic liquidsδ=−40.8 ppm for [NnBu4][SnCl3] in CH2Cl2 solution, which remains unchanged in the presence of a tenfold excess amount of [NnBu4]Cl.Fast atom bombardment (FAB) mass spectrometry, reported by Abbott's group, suggested the formation of [SnClnBu4][SnCl3] in 12CE shows five Sn−Cl stretching vibrations at Raman shifts between 300 and 100 cm−1, and this is consistent with that reported by Currie et al.3]− in Lewis basic C2mimCl–SnCl2 solutions (χSnCl2=0.2). For a Cv3 symmetric species, group theory predicts four Raman bands, two stretching modes (a1+e) and two bending modes (a1+e), and these occur at Raman shifts of 297, 256, 128, and 103 cm−1 for [SnCl3]− in diethyl ether solution.3]− in imidazolium chloride ionic liquids.3]− species for a higher‐energy system. As the 12CE electrolyte has a high concentration of chloride ions (4.5 mol L−1), the molar fraction of SnCl2 in this DES is 0.002 (for a 10 mmol L−1 solution), which is 200‐fold lower than that of the reported Lewis basic imidazolium system.The Raman spectrum of [BiCl4], a second steady‐state reduction wave  remains at a potential of −0.92 V at scan rates smaller than 10 mV s−1, and this is consistent with the presence of two Bi species in equilibrium in the solution.A set of rotating disk electrode (RDE) voltammograms was measured on a glassy carbon electrode at rotational rates ranging from 100 to 2500 rpm Figure . The RDED) of the tin and bismuth electroactive species were calculated with the Levich equationm for both [SnCl3]− and [BiCl6]3−. The diffusion coefficient for [SnCl3]− was found to be 1.49×10−7 cm2 s−1 at −0.6 V, and the diffusion coefficient for [BiCl6]3− was found to be 8.74×10−8 cm2 s−1 at −0.3 V. Both Levich plots show straight lines with correlation coefficients higher than 0.99. In contrast to the regression line for [SnCl3]− reduction, the line for [BiCl6]3− does not cross the origin. This is probably a consequence of the complex equilibrium of the Bi species in solution. The value of 8.74×10−8 cm2 s−1 for the diffusion coefficient of [BiCl6]3− should thus be considered a minimum value.The diffusion coefficients pyridinium chloride ionic liquid, the diffusion coefficient of the electroactive bismuth species, namely, Bi53+ ions, calculated from the Levich equation, was found to be 2.0×10−7 cm2 s−1,The diffusion coefficient for Bi−7 cm2 s−1 calculated for [SnCl3]− is similar to the value of 1.96×10−7 cm2 s−1 reported for SnCl2⋅2 H2O dissolved in 12CE.The diffusion coefficient of 1.49×10Chronoamperometric experiments were performed for both electrolytes Figure  by steppII and BiIII. After the capacitive decay, the current increases to a maximum (Imax) at a certain time (tmax). It is notable that the nucleation of Sn is much faster than that of Bi on the GC electrode, that is, the values of tmax are much shorter for the transients of [SnCl3]− reduction.Typical nucleation peaks are observed in the current–time transients for SnD values calculated from chronoamperometry are in good agreement with those calculated from the Levich equation, although the former data are more reliable for cases in which nucleation is involved. Also here, the values found for [BiCl6]3− are minimum values, because of its equilibrium with a second species.The Cottrell plots shown in Figure 3]−‐containing electrolytes, the nucleation at overpotentials of −0.08 and −0.13 V resembles the progressive model. Applying more negative overpotentials of −0.18 and −0.28 V changes the nucleation mechanism to instantaneous, which is consistent with the reports for SnCl2 in 12CE electrolyte at −1.20 V versus SCE  and 75 °C on GC.3/EMImCl2 melts.Dimensionless experimental transients were plotted together with the theoretical curves of the limiting cases for 3D instantaneous and progressive nucleation according to the Sharifker–Hills equations.III resemble progressive nucleation at overpotentials of −0.07 and −0.12 V, whereas at more negative overpotentials of −0.17 and −0.22 V, the dimensionless transients fit the instantaneous nucleation model. According to the Sharifker–Hills models for 3D nucleation with hemispherical‐diffusion‐controlled growth,DES solutions containing Bi2.24][SnCl3] and [NBu4][BiCl4] at SnII/BiIII molar ratios of 1:1 (black curve) and 2:1 (red curve).According to the binary phase diagram of Sn and Bi,III occurs at a potential of −0.29 V, and this is followed by a second reduction peak at a potential of −0.86 V. The reduction of SnII lies in between the two bismuth reduction peaks, at a potential of −0.44 V. In the anodic sweep, the dissolution of Sn takes place with a peak potential of −0.29 V, and this is followed by the dissolution of Bi more positively at a peak potential of +0.06 V.Both CV cycles show three well‐defined reduction peaks and two oxidation peaks. In the 1:1 ratio electrolyte, the reduction of BiIII in both electrolytes is the same, the first reduction peak of BiIII in the 1:1 ratio electrolyte is significantly broader and has a smaller peak current than that in the 2:1 ratio electrolyte. In the second consecutive cycles shown in Figure III reduction in Figure Although the concentration of Bi2.3II/BiIII solution. The CV curves of SnII, BiIII, and SnII/BiIII (2:1 molar ratio) in 12CE on gold electrodes can be found in the Supporting Information. The shift of the main stripping peak in the case of Sn to more positive potentials relative to the position of the main stripping peak in the CV curves on GC indicates the formation of intermetallic phases between Sn and Au (see below).Sn, Bi, and Sn–Bi coatings were deposited potentiostatically on gold‐sputtered glass substrates at different potentials. Sn–Bi deposits were prepared from a 2:1 SnII is more negative than that of BiIII. Energy‐dispersive X‐ray (EDX) spectroscopy analyses  revealed Sn/Bi ratios of 35:65, 53:47, and 59:41 wt % for samples deposited at −0.4, −0.5, and −0.6 V, respectively. Codeposition at the more‐negative potential resulted in an excess amount of Sn in the deposits, which is consistent with the presence of dendrites in this sample  images Figure  show thanBu4][SnCl3] in supercritical difluoromethane led to flowerlike morphologies.2⋅2 H2O in the same deep eutectic electrolyte used here2 in the choline chloride/urea (1:2 molar ratio) DES.The bismuth deposits from supercritical fluids showed a dendritic morphology on both the TiN and glassy carbon substrates,2 (ICSD 415968) phases are observed.Different crystalline phases were identified by analyzing the coatings by X‐ray diffraction, as presented in Figure 2, and Au3Sn.Studies of tin electrodeposited on gold electrodes from supercritical difluoromethanenBu4][BiCl4] in dichloromethane.The diffraction pattern of the electrodeposited bismuth resembles those of bismuth coatings deposited on Au from supercritical difluoromethane3II salts showed that the dominant species in the DES was [SnCl3]−, with a SnII/0 redox potential of −0.42 V versus Ag wire. In the case of BiIII, the speciation was not so clear, but the reduction potentials and Raman data pointed to [BiCl6]3− as the dominant ion, with a BiIII/0 redox potential of −0.08 V versus Ag wire. This hexachlorobismuthate(III) was found to be in equilibrium with a second species, the structure of which remains unclear, but it could also be reduced to the metal at a reduction peak potential of about −0.9 V.We described the electrodeposition of Sn, Bi, and binary alloys of the two metals from tetrabutylammonium chlorometalate salts in a choline chloride/ethylene glycol (1:2) deep eutectic solvent (DES) with high coulombic efficiency. The Raman spectra of the deep eutectic solvent containing Sn3]− and [BiCl6]3− were calculated from Levich and Cottrell equations. The values from both methods are in good agreement and revealed that the diffusion coefficient of [SnCl3]− was 1.4×10−7 cm2 s−1, whereas that of [BiCl6]3− was only 7×10−8 cm2 s−1. The latter has to be considered a minimum value, because the reduction of the BiIII species involves a complex equilibrium.The diffusion coefficients of [SnCl3] and [NnBu4][BiCl4] were prepared as described in the literature.−1 were heated to 60 °C and stirred until the salt had completely dissolved. Whereas [NnBu4][SnCl3] dissolved in a few minutes, [NnBu4][BiCl4] was considerably less soluble, and therefore, this mixture was stirred overnight.NnBu[SnCl3] a2O/O2). All experiments were conducted at the glove box temperature (30 °C). A silver wire was used as a quasireference electrode (RE). The RE was kept in a compartment containing 12CE, separated by a microporous frit, and placed approximately 3 mm from the working electrode (WE). Platinum wires were used as inert counter electrodes (CEs). Stationary (SE) and rotating disc (RDE) electrodes were used as WEs. The electrodes were made of nonporous glassy carbon , platinum , and gold (0.071 cm2). All WEs were polished to a mirror finish with alumina powder (0.03 μm grain size), rinsed with deionized water and acetone, and dried in air at 60 °C. Sn, Bi, and Sn–Bi films were electrodeposited potentiostatically onto evaporated gold‐on‐glass slides (1 cm2) that consisted of microscope slides with a 5 nm chromium adhesion layer and 100 nm of gold. Prior to electrochemical experiments, the gold‐on‐glass slides were cleaned by ultrasonic agitation in 2‐propanol for 10 min and then dried under a flow of nitrogen. A Metrohm Echo Chemie Autolab PGSTAT100 potentiostat/galvanostat controlled by NOVA 1.10 software and connected to the glove box was used to perform cyclic voltammetry and potential step techniques under computer control.The electrochemical experiments were performed in a three‐electrode cell within a dry, argon‐filled glove box  laser. Quartz cuvettes with a path length of 2 mm were filled with electrolyte (1 mL) in the glove box, closed with a Teflon cap, and sealed with Parafilm. Five 30 s scans were recorded for each sample. 119Sn{1H} NMR spectra were recorded from a 10 mm solution of [NnBu4][SnCl3] in 12CE containing a D2O capillary as lock and TbCl3 as a relaxation agent. Data acquisition used a Bruker AVII400 spectrometer and chemical shifts are referenced to SnMe4 (δ=0 ppm).The surface morphology was analyzed with a scanning electron microscope (ESEM Tescan 500 PA) equipped with an energy‐dispersive X‐ray (EDX) analyzer (INCA x‐act Oxford Instruments) for determining the elemental composition. X‐ray diffraction (XRD) was performed with an X‐ray powder diffractometer . Raman spectra of the BiThe authors declare no conflict of interest.As a service to our authors and readers, this journal provides supporting information supplied by the authors. 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