Polycrystalline Zn Research Articles

Androgynous {101¯2} twin in zinc

Under ambient conditions, Zn is a hexagonal metal with a large c/a ratio of 1.856. Plastic deformation is predominantly accommodated by basal 〈a〉 slip and compression twins on the {101¯2} planes. Increasing hydrostatic pressure drastically reduces the c/a ratio of Zn and, when a critical threshold of c/a=3 at about 10 GPa is crossed, the {101¯2} twins are predicted to change from compressive to tensile in nature. What happens at the transition point, when c/a=3, remains unknown. Here, we strain-cycle a textured polycrystalline sample of pure Zn at uniform hydrostatic pressures ranging between 2 and 17 GPa, over which the c/a ratio crosses the c/a=3 compressive-tensile transition for {101¯2} twins. During deformation, the state of the sample is monitored through x-ray diffraction to extract texture and internal strain evolution. By comparing the experimental results with the predictions of an elastoviscoplastic polycrystal simulation, we confirm the androgynous nature of {101¯2} twin response at low and high pressures. When c/a=3, polycrystalline Zn does not display any evidence of twinning and its plastic behavior is controlled by mostly basal and pyramidal 〈c+a〉 slip activity, with a very small contribution of prismatic 〈a〉 slip. Evidence for the activity of other {101¯n} twinning modes, which have been suggested for Zn under high pressure, are not observed. Published by the American Physical Society 2024

Oriented Zinc Metal Anode Based on Directional Recognition and Assembly.

The practical application of aqueous zinc batteries are highly limited by unsatisfied Zn anodes for the unavoidable dendrite growth and side reactions. Crystal orientation engineering is an effective way to overcome these inherent drawbacks. However, how to achieve Zn plating with manipulated crystallographic orientation is still a great challenge. Herein, a uniform (002)-oriented Zn metal anode is reported based on a directional cation recognition and crystal assembly strategy. The activated layered double hydroxide (Act-LDH) exhibits favorable adsorption energy with Zn2+ and high lattice matching with Zn (002) plane, which can be served as directional recognition layer to anchor Zn2+ and regulate crystallographic orientation of Zn as well. As demonstration, Zn crystals with ultrahigh ratio of (002)/(100) plane of 15.7 are assembled parallelly on horizontal Act-LDH, in which high CE of 99.85% maintains over 18000 cycles. The symmetric battery with (002)-oriented Zn shows stable plating/stripping process over 1650 and 420h at 1mAcm-2 /0.5mAhcm-2 and 10mAcm-2 /5mAhcm-2 , respectively, which is 9 and 12 times higher than unoriented polycrystalline Zn. Moreover, as-assembled full battery displays high specific capacity of 120mAhg-1 at 2Ag-1 over 1800 cycles.

Transparency and room temperature ferromagnetism in diluted magnetic polycrystalline Zn1−xCrxTe non-oxide II-VI semiconductor compounds

Polycrystalline Zn1−xCrxTe samples for x = 0.00, 0.05, 0.10, 0.15, 0.18, and 0.20 were synthesized by solid-state reaction, and their physical properties were studied for the purpose of identifying a novel non-oxide transparent diluted magnetic semiconductor (DMS). Their transport properties exhibit semiconducting behavior for low Cr concentrations and become conductors for higher Cr concentration concentrations. Ferromagnetic behavior was observed in Cr-doped ZnTe with Curie temperature Tc increasing as Cr concentration increases. At x = 0.20 Cr concentration, the system has Tc above room temperature, indicating an interesting II-VI ferromagnetic semiconductor. Furthermore, optical transparency in the visible light range was found to be 30–85 % for different Cr concentration concentrations. Also, according to the electrical transport measurement data in this study, the resistivity doesn’t exhibit any significant change as the temperature increases for x = 0.20. This consistent resistivity exhibits a possible candidacy for further studies of the sample Zn0.80Cr0.20Te for half-metallic ferromagnetic properties.

Crystal Plane Reconstruction and Thin Protective Coatings Formation for Superior Stable Zn Anodes Cycling 1300 h.

Some new insights into traditional metal pretreatment of anticorrosion for high stable Zn metal anodes are provided. A developed pretreatment methodology is employed to prefer the crystal plane of polycrystalline Zn and create 3.26µm protective coatings mainly consisting of organic polymers and zinc salts on Zn foils (ROZ@Zn). In this process, Zn metal exhibits a surface-preferred (001) crystal plane proved by electron backscattered diffraction. Preferred (001) crystal planes and ROZ coatings can regulate Zn2+ diffusion, promote flat growth of Zn, and prevent side reactions. As a result, ROZ@Zn symmetrical cells exhibit superior plating/stripping performance over 1300h. Impressively, it is significantly prolonged over 40times in comparison to the bare Zn symmetric cell at 5mAcm-2 . Moreover, Zn//MnO2 button cells have a high capacity retention of 96.3% after 1600cycles and pouch cells have a high capacity 122mAhg-1 after 200cycle at 5C. This work provides inspiration for high stable aqueous Zn metal batteries using the developed metal pretreatment of anticorrosion, which will be a viable, low-cost, and efficient technology. More interesting, it demonstrates the availability of reconstructing crystal planes by the largely heterogeneous reaction activation of the different crystal planes to H+ .

Low Residual Carrier Density and High In-Grain Mobility in Polycrystalline Zn3N2 Films on a Glass Substrate

Low Residual Carrier Density and High In-Grain Mobility in Polycrystalline Zn₃N₂ Films on a Glass Substrate

Synthesis and Characterization of the Ternary Nitride Semiconductor Zn2VN3: Theoretical Prediction, Combinatorial Screening, and Epitaxial Stabilization

Computationally guided high-throughput synthesis is used to explore the Zn-V-N phase space, resulting in the synthesis of a novel ternary nitride Zn$_2$VN$_3$. Following a combinatorial PVD screening, we isolate the phase and synthesize polycrystalline Zn$_2$VN$_3$ thin films with wurtzite structure on conventional borosilicate glass substrates. In addition, we demonstrate that cation-disordered, but phase-pure (002)-textured, Zn$_2$VN$_3$ thin films can be grown using epitaxial stabilization on {\alpha}-Al2O3 (0001) substrates at remarkably low growth temperatures well below 200 {\deg}C. The structural properties and phase composition of the Zn$_2$VN$_3$ films are studied in detail using XRD and (S)TEM techniques. The composition as well as chemical state of the constituent elements are studied using RBS/ERDA as well as XPS/HAXPES methods. These analyses reveal a stoichiometric material with no oxygen contamination, besides a thin surface oxide. We find that Zn$_2$VN$_3$ is a weakly-doped p-type semiconductor demonstrating broadband room-temperature photoluminescence spanning the range between 2 eV and 3 eV. In addition, the electronic properties can be tuned over a wide range via isostructural alloying on the cation site, making this a promising material for optoelectronic applications.

Structural and magnetic properties of polycrystalline Zn1−xMnxO films synthesized on glass and p-type Si substrates using Sol–Gel technique

Structural and magnetic properties of polycrystalline Zn1−xMnxO films synthesized on glass and p-type Si substrates using Sol–Gel technique

Factors affecting Confidence Index in EBSD analysis

Automated EBSD analysis systems have been used for over two decades relying on the fact that the correctness of a particular orientation solution could be assessed through the calculation of a Confidence Index. However, such an index only reports whether a particular solution stands out among any other possible solutions, by receiving a larger number of votes than others, and does not necessarily imply that the corresponding orientation is correct. This issue is addressed in the present paper, where the correctness of solutions and the factors that might affect it have been studied for single crystal Si and polycrystalline Zn. The results were compared to those presented in previous papers where this matter was studied in particular for an FCC material. It was observed that about 90% of the solutions were correct if they were obtained using a confidence index of 0.1 using at least 8 Hough bands regardless of the crystallographic structure or orientation.

A Catalyst Based on Silver-Zinc Bimetal for Electrochemical Reduction of CO2 to CO

Energy and environmental issues have become the most significant challenges for human beings in the 21st century [1]. Among these issues, the continuing use of fossil fuels has led to increase the concentration of carbon dioxide (CO2) in the atmosphere, which has caused global climate change [2]. However, the CO2 reduction reaction have challenges due to the high overpotential and kinetically sluggish multi-electron transfer process. To solve these disadvantages, various bimetallic-based catalytic materials have reported. Because it provides a great potential for catalytic activity owing to their synergetic effects [3]. In the present study, we prepared an AgZn bimetallic catalysts by physical vapor deposition (PVD), which provides an ideal model for the electrochemical reduction of CO2 to CO. Three samples with different thicknesses of 2 nm, 5 nm, and 10 nm Ag layers, deposited on polycrystalline Zn pellets (poly Zn), were used for the electroreduction of CO2.All electrochemical experiments were conducted in a three-electrode system employing a potentiostat. An H-type electrochemical cell separated by a slice of Nafion 211 membrane was used for the CO2 electrochemical reduction. The electrolyte (0.1 M KHCO3) was saturated with CO2 (pH 6.8). The produced gas was directly introduced into the gas sampling loop of a gas chromatograph, which was equipped with a flame ionization detector (FID) for CO analysis and a thermal conductivity detector (TCD) for H2 analysis.The morphologies of Ag sputtered on the poly Zn were determined by TEM. It is observed that a 2 nm thickness Ag film forms Ag clusters of nearly circular shapes, which is likely an isolated island. As the thickness of Ag increases, the surface area covered by Ag also increases. The 10 nm sample shows the surface almost fully covered by Ag. All the XRD peaks of the Zn-based catalysts are indexed to the hexagonal wurtzite structure of Zn. However, the diffraction pattern of the 2AZ catalyst matches well with that of the poly Zn pellets and does not match with the diffraction pattern of Ag. It is because the amount of silver is too small to be detected. However, for the 5AZ and 10AZ catalysts, the diffraction peaks of Ag and Zn are observed. XPS was performed to demostrate the synergetic effect. Interestingly, the binding energy of Ag 3d of the AgZn compared to that for poly Ag is shifted towards a lower binding energy. Synergetic effect of AgZn catalyst could be attributed to the electron transfer from Ag to Zn, because Ag has a lower work function than Zn.To confirm the performance of CO2 reduction, the electrochemical experiments were conducted in CO2 saturated 0.1 M KHCO3 (pH =6.8) solution using a homemade H-type cell with a three-electrode system. The total current density of the 2AZ catalyst (3.53 mA cm−2) at −1.0 V is 2.05, 1.17, 1.38, and 1.28-fold higher than the total current densities of the poly Zn (1.72 mA cm−2), poly Ag (3.02 mA cm−2), 5AZ (2.56 mA cm−2), and 10AZ (2.76 mA cm−2), respectively. The 2AZ catalyst has the maximum CO conversion FE of 84.2% at a potential of −1.0 V vs. RHE, which is approximately 2.3-fold higher than that of poly Zn (35.9%), 1.5-fold higher than that of poly Ag (55.3%). the 2AZ catalyst exhibited excellent activity and selectivity for CO2 reduction to CO, even better than poly Au.Conclusively, we prepared AgZn bimetallic catalysts using a physical vapor deposition sputtering system. The 2 nm Ag deposited Zn catalyst selectively catalyzed the electrochemical CO2 reduction to CO with the FE of 84.2% at −1.0 V. The XPS analysis demonstrates a red-shift of the binding energy in the Ag 3d spectra, which results from the charge transfer from Ag to Zn. This indicates that the AgZn bimetallic structure can improve the surface charge transfer for CO2 reduction. This study can provide a new direction for further study on the electrochemical reduction of CO2 to CO.[1] H.-T. Pao, C.-C. Chen, J. Clean. Prod. 206 (2019) 907–919.[2] D. D. Zhu, J. L. Liu, S. Z. Qiao, Adv. Mater. 28 (2016) 3423-3452.[3] J.-H. Kim, S.-W. Yun, K. Shim, S.-H. You, S.-M. Jung, H. Kweon, S. H. Joo, Y. H. Moon, Y.-T. Kim, ACS Appl. Energy Mater. 3 (2020) 1423–1428.

Angular Distributions during Magnetron Sputtering of Polycrystalline Mg, Al, Si, Ti, Cr, Cu, Zn, Ge, Zr, Nb, Mo, Ag, In, Sn, W, Pt, Au, and Bi Targets

The results of experimental investigations of the angular distributions during magnetron sputtering of Mg, Al, Si, Ti, Cr, Cu, Zn, Ge, Zr, Nb, Mo, Ag, In, Sn, W, Pt, Au, and Bi targets in argon at a constant current are presented. The operating conditions during the experiments corresponded to the values typical of industrial sputtering equipment. The angular distribution of the material flow was calculated based on the measured thickness of the coating deposited on two flexible ribbon substrates. These substrates were fixed in place on a substrate holder in the form of two crossed half-rings that were equidistant from the center of the magnetron target (the curvature radius was 100 mm). The influence of the magnitude and shape of the magnetic field near the surface of the sputtered cathode on the angular distribution was also investigated. The results can be used as the source data for calculating the profile of the coating during magnetron sputtering.

Structural, optical and magnetic characterization of nanorod-shaped polycrystalline Zn1−xMnxO films synthesized using sol–gel technique

The structural, optical and magnetic properties of nanorod structured polycrystalline Zn1−xMnxO3 films $$\left( {0 \le x \le 0.1} \right)$$ grown on glass substrate using Sol–Gel technique have been investigated. X-ray diffraction (XRD) analysis reveals average grain sizes from 15 to 25 nm. There was gradual increase in both the crystallite size and lattice constant with increase in Mn content up to 0.2%, and then decrease of them with further increase in Mn content. The same result has been confirmed by SEM experiments. It has been revealed that the band gap value of Zn1−xMnxO film decreases from 3.34 to 2.97 eV with an increase in Mn concentration from x = 0.0 to 0.1, which is in agreement with the previously reported results. The studies of the magnetization and magnetic resonance of Zn1−xMnxO films revealed the presence of the paramagnetic state without any magnetic ordering.

Electrochemical synthesize and characterization of ZnO / ZnS nanostructures for hydrogen production

In present study, zinc oxide/zinc sulfide (ZnO/ZnS) nanostructures were fabricated by anodization of Zn. The morphological, structural and compositional properties of ZnO/ZnS were studied by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). From FESEM results, well-defined and smooth spherical-like ZnO/ZnS nanostructures were obtained with tube-like ZnO nanostructures underneath the compact layer. XRD patterns revealed that achieved materials offer high crystallinity hexagonal ZnO as dominant with hexagonal close-packed polycrystalline Zn. Moreover, measure of water contact angle was realized to learn about wetting property of the electrodes. Electrochemical impedance spectroscopy (EIS) was recorded to examine electrocatalytic performance of electrodes against hydrogen evolution reaction (HER) in 1 M KOH solution. The values of energy consumption and energy efficiency were calculated as 571.9 kJ mol−1 and 49.5% at current density of 50 mA cm−2 for the HER on 40-ZnO/ZnS/Zn electrode at 25°C.

Design of Highly Reversible Zinc Anodes for Aqueous Batteries Using Preferentially Oriented Electrolytic Zinc

AbstractRechargeable zinc‐based batteries have attracted a growing interest due to their intrinsic safety, low environmental impact and potentially very low cost. However, there still remains significant hurdles to achieve cells of commercial interest. Conventional commercial Zn anodes are formed from large, polycrystalline particles with limited control over the shape and size. In this study, preferentially oriented electrolytic Zn (e‐Zn) particles with hexagonal shape and controlled size (∼100 μm) were synthesized and physically characterized by SEM, XRD and BET techniques. The corrosion, discharge and cycling behavior of e‐Zn particles were analyzed in KOH alkaline media. It was found that preferentially oriented e‐Zn particles with low surface area have lower corrosion than Zn powder and 99 % reduced corrosion rate with respect to polycrystalline Zn wire. Furthermore, e‐Zn electrodes were successfully scaled up and showed remarkable reversibility in symmetric cells at a high rate of 20 mA cm−2 for 640 h. e‐Zn/KOH/MnO2 full cells were also demonstrated with ca. 6 times longer cycle life than Zn powder with a lower H2 gassing rate at 10 % Zn DoD and C/20 rate. In addition, a comparison between alkaline vs. mild acidic electrolyte was made in terms of reversibility and structural changes of preferentially oriented e‐Zn electrodes where superior cycling was observed in ZnSO4 for 2000 h.

Ag layer deposited on Zn by physical vapor deposition with enhanced CO selectivity for electrochemical CO2 reduction

The electrocatalytic reduction of carbon dioxide (CO2) is a promising way to reduce CO2 and to produce valuable products. However, CO2 reduction still have challenges, such as, low catalytic activity, selectivity, and stability of catalysts. In the present study, we prepared Ag nanolayers (2, 5, and 10 nm) sputtered on polycrystalline Zn (AgZn) catalysts by a physical vapor deposition for the electrochemical CO2 reduction to carbon monoxide (CO). Among them, a 2 nm Ag layer deposited catalyst on Zn showed the faradaic efficiency of 84.2% with a CO partial current density of 2.97 mA cm−2 at −1.0 V vs. RHE. Such enhanced electrochemical reduction activity, selectivity, and stability were attributed to the synergetic effect between Ag and Zn, which was confirmed by X-ray photoelectron spectroscopy (XPS) data. The results indicate that the proposed catalyst can provide one of efficient ways for the CO2 reduction reaction.

Phenomenology of the effect of ion irradiation on the work function of metals

Polycrystalline Al and Zn samples were irradiated with 30 keV Ar+ ions at room temperature and the changes of their electron work functions, Φ were measured by the Kelvin method. Similarly to what was earlier experienced with stainless steel the changes of Φ as a function of displacement per atom (DPA) were seen to be of extremal character. This can be considered as a manifestation of competing formation and annealing of displacements. Comparing the Lang-Kohn theory of work function with the present experimental results the changes of the Wigner-Seitz radii were evaluated. A differential law for the dependence of the Wigner-Seitz radius on DPA is proposed.

Nanoscale Scanning Electrochemical Cell Microscopy and Correlative Surface Structural Analysis to Map Anodic and Cathodic Reactions on Polycrystalline Zn in Acid Media

Scanning electrochemical cell microscopy (SECCM) is used to map anodic and cathodic processes on polycrystalline zinc in 10 mM H2SO4, at the nanoscale. Electrochemical maps are correlated directly with structural data from electron backscatter diffraction applied to the same regions of the surface, and density functional theory (DFT) calculations are used to rationalize the data. Preliminary data on droplet stability with SECCM point measurements indicated that there was a significant spreading of the meniscus cell with an air atmosphere, attributed to changes in pH during the oxygen reduction reaction, compromising the lateral resolution of the SECCM measurement. Experiments with an argon atmosphere, as well as the application of a hydrophobic n-dodecane oil layer on the Zn interface, prevented spreading. Electrochemical maps of polycrystalline Zn surface under an Ar atmosphere indicated that the hydrogen evolution reaction (HER) and Zn electrodissolution on individual low-index grains decreased in the order DFT calculations revealed a correlation between experimental values of current associated with HER and Zn dissolution reactions and the predicted hydrogen adsorption and Zn dissolution energies on individual facets, respectively. This work further advances SECCM as a technique for probing electrified interfaces and demonstrates its applicability to reactive metals.

Pulsed laser deposition of Zn(O,Se) layers in nitrogen background Pressure

Zinc oxy-selenide Zn(O,Se) is a novel material, that can replace the toxic CdS buffer layer in thin film solar cells and other optoelectronic devices. In this paper a systematic study of the structural, optical and electrical properties of Zn(O,Se) layers, grown by pulsed laser deposition under 50 mTorr of nitrogen background pressure, over a wide range of the substrate temperature, from RT to 600 °C, is reported. XRD, Raman, HR-SEM, XPS, UV-Vis techniques and Hall effect measurements have been used to investigate the structural, and optoelectronic properties of Zn(O,Se) layers. XRD analysis revealed that the polycrystalline ternary Zn(O,Se) phase formed at 500 °C. Raman analysis confirmed the formation of the polycrystalline Zn(O,Se) phase at 500 °C and an amorphous phase at substrate temperatures below 500 °C. Similarly, XPS analysis accompanied with the modified Auger parameters confirmed formation of ternary Zn(O,Se) layer at 500 °C as well. HR-SEM investigation showed the growth of homogenous, dense and adherent films onto a glass substrate. Furthermore, optical studies revealed that all prepared films are practically transparent in the visible region of the spectrum, with a band gap around 3 eV. Hall effect measurements revealed that conductivity, and electron concentration, increased by four orders of magnitude at 600 °C. It was found, that nitrogen background pressure maintained stable ratios of elemental contents in the whole range of the substrate temperature for Zn(O,Se) layers.

Influence of sintering temperature on microstructure, magnetic properties of vacuum sintered Co (-Zn)-Ni-Al alloys

Co38Ni35Al27 and Co35Zn10Ni32Al23 ferromagnetic shape memory alloys were prepared via facile powder metallurgy and vacuum sintering technique. The influence of sintering temperature on phase transformation behaviour, microstructure and magnetic properties were investigated. The rise in peak intensity of A2-phase shows that the alloy is rich in martensitic-phase in the polycrystalline cubic B2-phase structure and Zn incorporation leads to the reduction in austenite-phase. The needle-shaped cobalt precipitates on predominant martensite A2-phase, shows Widmanstatten-like structure in the samples sintered at 673 K. The saturation magnetization was found to be 87.92 and 96.2 emu/g for Co38Ni35Al27 and Co35Zn10Ni32Al23 alloy. The existence of non-interacting single-domain particles were observed and proved using Stoner-Wohlfarth model.

Intergranular/transgranular fracture in the liquid metal embrittlement of polycrystalline zinc

Tensile tests were performed on polycrystalline Zn specimens in contact with liquid Ga, In, In–Bi eutectic alloy, or Sn–Bi eutectic alloy below 450 K. These low-melting-point metals and alloys embrittled Zn specimens when they were in the liquid state. Although single-crystalline Zn is known to be embrittled by liquid Ga, intergranular cracking occurred in polycrystalline Zn in the presence of liquid Ga, while transgranular cracking occurred in the presence of In and Sn. Just above the melting point of Ga, only Ga atoms were found to penetrate along the grain boundaries of polycrystalline Zn. Although all these embrittlers reduced the cleavage fracture stress, only Ga atoms in the grain boundaries significantly reduced the strength of the grain boundaries, resulting in intergranular cracking. For the specimens in contact with liquid Ga, the incidence of transgranular cleavage fractures increased at high temperatures due to the reduction in the number of Ga atoms in the grain boundaries by diffusion into the grains.

Fabrication and investigation of ultravialet Au-Zn x Cd1–x S-Mo-structures

For the first time fabricated and investigated the photovoltaic characteristics of Au-Zn x Cd1–x S-Mofilm structural injection photo detectors sensitive to narrow the ultraviolet region of the electromagnetic spectrum, based on polycrystalline Zn x Cd1–x S layers. It was found by adjusting the flow of ZnS and CdS coming to the surface Mo substrate can control the shape of the spectral sensitivity of the Au-Zn x Cd1–x S-Mo-film structural injection photo detectors. The results will allow to optimize the structure of photo detectors and solar cells based on polycrystalline thin film solar cells.