Zinc Diffusion Research Articles

Analysis of Structures at the Boundary of Contact Melting Al–Mg–Mn and Zn Based Alloys

The processes of contact melting of the AMg6 (Al-6%Mg-1%Mn) alloy with Zn–Cu–Al solder and the model Zn–Al alloy, as well as the structure of the contact fusion zone, are studied. Samples were obtained in two stages. At the first step, the solder was mechanically applied (tinned) to the surface of the AMg6 plates. Аt the second step, the resulting composite samples were subjected to heat treatment with a varied exposure time in the liquid state. According to the data of metallographic and X-ray diffraction analyses, as well as differential scanning calorimetry, it was shown that already at the tinning stage the active interaction between Zn and Al occurs, which leads to the formation of a developed microstructure in the joint zone. The presence of copper in the solder HTS-2000 reduces the melting point of the Zn-Al alloy by 30-40°C and improves the conditions for contact interaction with the grade AMg6 matrix. Active diffusion of zinc ensures the formation of an extensive melting zone during heat treatment, while zinc-rich areas during crystallization contain the Zn5Cu intermetallic phase, which prevents the formation of intermetallic ZnxMgy compounds, which does not lead to embrittlement of the contact zone.

Boosting Zn-Ion Storage Behavior of Pre-Intercalated MXene with Black Phosphorus toward Self-Powered Systems.

MXene-based Zn-ion capacitors (ZICs) with adsorption-type and battery-type electrodes demonstrate high energy storage and anti-self-discharge capabilities, potentially being paired with triboelectric nanogenerators (TENGs) to construct self-powered systems. Nevertheless, inadequate interlayer spacing, deficient active sites, and compact self-restacking of MXene flakes pose hurdles for MXene-based ZICs, limiting their applications. Herein, black phosphorus (BP)-Zn-MXene hybrid is formulated for MXene-based ZIC via a two-step molecular engineering strategy of Zn-ion pre-intercalation and BP nanosheet assembly. Zn ions as intercalators induce cross-linking of MXene flakes with expandable interlayer spacing to serve as scaffolds for BP nanosheets, thereby providing sufficient accessible active sites and efficient migration routes for enhanced Zn-ion storage. The density functional theory calculations affirm that zinc adsorption and diffusion kinetics are significantly improved in the hybrid. A wearable ZIC with the hybrid delivers a competitive areal energy of 426.3µWhcm-2 and ultra-low self-discharge rate of 7.0mVh-1, achieving remarkable electrochemical matching with TENGs in terms of low energy loss, matched capacity, and fast Zn-ion storage. The resultant self-powered system efficiently collects and stores energy from human motion to power microelectronics. This work advances the Zn-ion storage of MXene-based ZICs and their synergy with TENG in self-powered systems.

Mullite Mineral-Derived Robust Solid Electrolyte Enables Polyiodide Shuttle-Free Zinc-Iodine Batteries.

Zinc dendrite, active iodine dissolution, and polyiodide shuttle caused by the strong interaction between liquid electrolyte and solid electrode are the chief culprits for the capacity attenuation of aqueous zinc-iodine batteries (ZIBs). Herein, mullite is adopted as raw material to prepare Zn-based solid-state electrolyte (Zn-ML) for ZIBs through zinc ion exchange strategy. Owing to the merits of low electronic conductivity, low zinc diffusion energy barrier, and strong polyiodide adsorption capability, Zn-ML electrolyte can effectively isolate the redox reactions of zinc anode and AC@I2 cathode, guide the reversible zinc deposition behavior, and inhibit the active iodine dissolution as well as polyiodide shuttle during cycling process. As expected, wide operating voltage window of 2.7V (vs Zn2+/Zn), high Zn2+ transference number of 0.51, and low activation energy barrier of 29.7kJ mol-1 can be achieved for the solid-state Zn//Zn cells. Meanwhile, high reversible capacity of 127.4 and 107.6 mAh g-1 can be maintained at 0.5 and 1 A g-1 after 3000 and 2100 cycles for the solid-state Zn//AC@I2 batteries, corresponding to high-capacity retention ratio of 85.2% and 80.7%, respectively. This study will inspire the development of mineral-derived solid electrolyte, and facilitate its application in Zn-based secondary batteries.

Electroless brassing of historical artefacts

Abstract The topic of this work was the investigation of an alternative brassing technique consisting of electroless zinc plating of a copper object in a strongly alkaline solution and subsequent annealing to achieve a characteristic brass appearance. Within the scope of the work was the determination of the mechanism of zinc deposition on the copper surface, the optimisation of the NaOH concentration (30 and 40 wt. %), time of deposition (5-120 min), as well as temperature (150 and 200 °C) and annealing time (15 – 60 min). Electrochemical methods (potentiodynamic curves and open-circuit potential), metallography, X-ray diffraction (XRD), and glow-discharge optical emission spectroscopy (GD-OES) were used to study the brassing mechanism. Electrochemical measurements have shown that zinc powder significantly decreases the surface potential of copper to the value of zinc itself and also acts as a reducing agent. The diffusion of zinc in copper was found to occur during the primary deposition of zinc with the formation of the γ phase (Cu5Zn8). The optimal NaOH concentration is 40 wt.% and the deposition time is 60 min. The optimal conditions of annealing are 200 °C and 60 min. The primary γ phase is transformed during the annealing process into β and α phases.

Study of Zinc Diffusion Based on S, N-Codoped Honeycomb Carbon Cathodes for High-Performance Zinc-Ion Capacitors.

Capacitors with zinc ions, with excellent stabilities, low cost, and high energy density, are expected to be promising energy storage devices. However, the development of zinc-ion capacitors is quietly restricted by low specific capacity and cycling stability. Herein, to overcome these limitations, honeycomb-structured S, N-codoped carbon (SNPC) is constructed by one-pot calcination of waste corn bracts and thiourea. The honeycomb structure of SNPC is demonstrated to provide abundant active sites that can enhance the extron/ion transport, conductivity for high power export, and ion adsorption capacity in energy storage applications, leading to a higher electrochemical performance achieved. The electrolytes of zinc salt have also been studied. It reveals that the SNPC electrode presents the best electrochemical performance in a 2 M ZnSO4 and 0.5 M ZnCl2 electrolyte mixture because in the electrolyte mixture, Cl- can replace the existing bound water in the solvation structure to form an anion-type water-free solvation structure ZnCl42-. The SNPC-800 electrode with a highly improved surface area (∼909.0 m2 g-1) is proved to be more suitable as the electrode than other materials. Aqueous zinc-ion capacitors (ZICs) have been assembled by the honeycomb-structured SNPC-800 as the cathode, which can achieve a relatively wide working voltage range of 0.1-1.8 V. The SNPC-800 ZICs exhibit a superior specific capacity of 179.1 mA h g-1 at 0.1 A g-1. The energy density of SNPC-800 ZICs reaches an impressive value of 89.6 Wh kg-1 at 53.8 W kg-1, and it sustains 28.3 Wh kg-1 at 1997.6 W kg-1. In addition, there is 99.8% capacity retention in the SNPC-800 ZICs over 5000 cycles. The absorption energy in SPNC is much higher than that in undoped CPC, as confirmed by density functional theory, which reveals that introducing of heteroatoms (S, N) has a comparatively active advantage at increasing the Zn-ion storage capacity. This work proposes a practical strategy for the effective recycling of waste biomass materials into honeycomb carbon electrode materials. Moreover, the honeycomb carbon-based ZICs with excellent electrochemical performance and long-term cycling stability possess great potential to be a superior cathode in practical applications.

Three‐Dimensional Ordered Macroporous Amorphous WO3 Arrays for Zinc‐Based Electrochromic Device with Large Light Modulation and Fast Switching

AbstractElectrochromic devices have important applications in building energy conservation, next‐generation displaying, and security encryption, while durable and high‐performance electrochromic materials are highly desirable. Herein, a Zn‐based electrochromic smart window by using 3D ordered macroporous amorphous WO3 (a‐WO3) arrays as cathode is reported. Benefiting from a 3D ordered macroporous structure with a high specific surface area that accelerates the ion diffusion and migration, and the oxygen vacancy modulated a‐WO3 providing abundant zinc ion insertion channels, the as‐fabricated zinc‐based a‐WO3 inverse opal (a‐WO3‐IO) device exhibits excellent electrochromic properties, including large light modulation (83% optical contrast at 700 nm), fast response time (5.3 s for coloring and 3.2 s for bleaching), and robust cycling stability. Moreover, a solid‐state a‐WO3‐IO prototype electrochromic smart window is demonstrated for light modulation, electronic display, and power supply. Furthermore, experimental results and theoretical calculations reveal that 3D macroporous amorphous WO3 with rich oxygen vacancies can enhance the zinc ion absorption and diffusion, leading to the enhancement of electrochromic performance.

The Mechanism Behind the Annealing‐Induced Reduction of Infrared Absorption in Zinc‐Hyperdoped Silicon

Pulsed laser hyperdoping is widely investigated as an effective method for expanding the infrared absorption of silicon. Prior to further device fabrication, thermal treatment is commonly applied to hyperdoped silicon to repair lattice defects and activate dopants. However, it is observed that thermal treatment adversely affects the infrared absorption of hyperdoped silicon, and the underlying mechanisms remain incompletely understood. Herein, zinc‐hyperdoped silicon (Si:Zn) is prepared using vacuum magnetron sputtering combined with femtosecond laser pulses, and the mechanisms of the reduction in infrared absorption during conventional annealing of Si:Zn samples are investigated. The diffusion of zinc and its precipitation as zinc clusters in silicon are observed during the annealing process, leading to a decrease in the concentration of zinc dopants within the silicon lattice and consequent attenuation of infrared absorption. Building upon this understanding, the approach of short timescale annealing subjected to infrared rapid thermal annealing furnace is proposed to be employed as a method to mitigate the adverse effects of zinc transitional precipitation, resulting in enhancement of the performance of Si:Zn optoelectronic devices.

Double Zinc Diffusion Optimization for Charge Persistence Reduction in InGaAs/InP SPADs

Double Zinc Diffusion Optimization for Charge Persistence Reduction in InGaAs/InP SPADs

Lightly doped In0.53Ga0.47As/InP SWIR photodetectors with diffusion barrier structure

A diffusion barrier structure is proposed to control the accuracies of the Zinc diffusion velocity and depth for lightly doped short-wave infrared (SWIR) InGaAs planar photodetectors. By employing scanning capacitance microscopy and scanning electron microscopy characterizations, the Zinc diffusion profiles were investigated. The introducing of a moderately doped interlayer effectively tailored the diffusion front with reduced depth. In0.53Ga0.47As/InP PIN photodetectors with different structures were fabricated and characterized. Compared with the typical structure, the barrier detector exhibited a significantly lower dark current as well as an approximately three times higher peak detectivity. These results indicated that the diffusion barrier structure is promising for the fabrication of SWIR InGaAs focal plane arrays with both low capacitance and reduced dark current.

In situ constructing heterogeneous Mn(VO3)2/NaVO3 nanoribbons as high-performance cathodes for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are emerging as a promising candidate, enjoying accolades for their safety, low cost, and ease of operation. However, some challenges like the slow kinetics and structural collapse of cathode materials hamper their rate capability and cyclability. To address these limitations, a heterogeneous Mn(VO3)2/NaVO3 (MNVO) nanoribbon hybrid was designed as high-performance cathodes for zinc storage. Owing to the heterointerface between Mn(VO3)2 and NaVO3 boosting the charge-transfer kinetics and leading to enhanced zinc diffusion kinetics, the MNVO exhibits a high specific capacity of 381.2 mAh g−1 at 0.2 A g−1, high rate capability (286.7 mAh g−1 at 5 A g−1), and excellent electrochemical kinetics. Additionally, the MNVO cathode exhibits stable cyclability (a high-capacity retention rate of 95.7% at 1 A g−1 after 200 cycles) and excellent long-term cyclability (a high-capacity retention of 83.0% after 2000 cycles). Moreover, the zinc storage mechanism of co-intercalation of Zn2+ and H2O into the host of MNVO were investigated by ex situ XRD and XPS characterizations. Our work offers new insight and understanding into the development of high-performance cathode materials through constructing heterogeneous structure.

Finishing Additively Manufactured Ti6Al4V Alloy with Low-Energy Electrical Discharges.

Additive manufacturing has garnered significant interest in various industries due to its flexibility and capability to produce parts with complex shapes. However, issues related to surface quality, such as roughness and microstructural defects, necessitate the use of post-processing techniques to achieve the desired properties. Ti6Al4V alloy, produced additively, was finished using low-energy discharges, and the new surface integrity properties resulting from the induced heat energy were investigated. To further understand the influence of discharge energy on the formation of the new layer, roughness parameters and power spectral density were used to characterize the surface topography. SEM and EDS analyses were performed to examine the morphology and microstructural defects such as microcracks. The results indicate that the heat energy induced by the discharge improved the properties of the surface. SEM analysis revealed that the new layer was characterized by a reduction in defects such as unmelted particles, the balling effect, and microcracks. At the lowest investigated discharge energy of E = 0.21 mJ, surface roughness, Sa, was reduced by about 69%, which is equal to about 2 μm, accompanied by a significant decrease in microcracks. EDS analysis indicated that the diffusion of copper and zinc from the electrode to the top surface was related to the discharge energy. Furthermore, prediction models of the influence of wire electrical discharge polishing parameters, including discharge energy, wire speed, and time interval, on the surface roughness and material removal rate (MRR) were developed using the response surface methodology.

Analysis of Zn diffusion in various crystallographic directions of GaN grown by HVPE

This work presents the diffusion mechanism of zinc in gallium nitride. Halide vapor phase epitaxy layers were deposited on native ammonothermal seeds of three crystallographic orientations: c - (0001), m - (10-10), and a - (11–20). The surfaces were prepared to an epi-ready state by mechanical and chemical-mechanical polishing. Zinc ions were then implanted with energy of 230 keV and fluence 1016 cm−2 to create an infinite-like source of zinc atoms near the surface. The implanted samples were annealed by ultra-high-pressure method in the temperature range 1250–1450 °C at nitrogen pressure of 1 GPa for 4.5 h to remove the post-implantation structural damage and trigger the diffusion of zinc into the depth of the gallium nitride layers. X-ray diffraction measurements were performed for samples at every stage of the process: as-grown, as-implanted and annealed in order to investigate the evolution of the structural quality. Secondary ion mass spectrometry was employed to analyze depth profiles of zinc and concentrations of impurities. Positron annihilation spectroscopy and low-temperature photoluminescence were employed to assess the defect evolution in the samples. The results showed a strong dependence of zinc diffusion on the crystallographic direction of gallium nitride crystal growth. The depth profiles measured for the analyzed crystallographic directions differed in shape and range of zinc penetration. Diffusion coefficients were calculated for all the analyzed temperatures. The pre-exponential diffusion factor and activation energy were determined.

High Speed 1550 nm Indium Gallium Arsenide-Indium Phosphide Photodetector

This paper presents preliminary results of a high speed 1550 nm indium gallium arsenide (InGaAs)-based mesa-type modified uni-traveling carrier photodiode (M-UTC-PD) structure. Conventional UTC-PD refers to P-I-N type photodiodes which selectively use electrons as active carriers. Photons absorbed in the relatively thin P-type absorber create minority carriers which are field accelerated toward a depleted collector thereby establishing high velocity ballistic transport, making these structures applicable for high speed applications. The M-UTC-PD structure presented uses spatially tailored P-type absorber regions to limit minority carrier generation both in the lateral and axial dimensions. Utilizing an otherwise conventional UTC-PD epitaxial structure where the top P-type layers are undoped, the spatially tailored P-type regions are defined by closed ampoule Zinc diffusion techniques. The M-UTC-PD structure presented utilizes a series of nested p-doped rings within a mesa structure to limit dark current and reduce overall capacitance to improve high speed operation. Two photodiode structures will be investigated for this research project, a conventional UTC-PD structure and a modified structure, utilizing similar device designs, epitaxial designs and fabrication processes. The conventional structure will be utilized for fabrication process development, verification of epi quality and development of rapid prototyping approach toward chip-based testing and subsequent high speed RF testing procedures. Conventional UTC-PD device results will be used as a comparison to quantify the performance of the M-UTC-PD structure utilizing Zn-doped defined p-type absorber regions. Results are given for chip tests of UTC-PD chips verifying epitaxial quality and fabrication process, subsequent testing of packaged devices and RF analysis remains. Process development of the Zn-doped devices is underway, once completed, these devices will be compared to the base design to quantify performance enhancement associated with the modified design.

Effect of zinc diffusion regimes from a metallic layer on the emission and current parameters of InGaAs/AlGaAs/GaAs structures

The study represents the light and current parameters of an InGaAs/AlGaAs/GaAs double heterostructure, the layers of which were simultaneously subjected to doping and intermixing by rapid thermal annealing of zinc from a metal layer with a SiO2 coating at different temperatures and firing times: 1) 700 °C, 5 min; 2) 650 °C, 5 min; 3) 650 °C, 15 min. A comparison of samples with different temperatures and times of zinc annealing showed that an increase in the time and temperature of the process increases the shift of the luminescence maximum peak to the short-wavelength region. The best shift was 87 nm.

Interfacial Microstructure Evaluation of Precisely Controlled Friction Stir Welding Joints of Al/Mg Dissimilar Alloys with Zn Interlayer

In this study, a penetration-controlled friction stir welding (FSW) technique was employed to lap weld dissimilar Al/Mg alloys, incorporating a Zn interlayer. The joint’s microstructure, interfacial reaction, and phase composition were analyzed through optical microscopy, scanning electron microscopy, and X-ray diffraction. The findings demonstrate the formation of a hybrid joint comprising a FSWed region and a diffusion bonding region achieved by introducing a pure Zn interlayer at the Al/Mg interface. Within the FSWed region, the zinc was fully extruded, leading to favorable interface bonding. In contrast, the diffusion bonding region exhibited an aluminum–zinc diffusion reaction layer, an incompletely reacted zinc layer, and a zinc–magnesium diffusion reaction layer. Notably, no Al-Mg intermetallic compounds (IMCs) were observed in either the FSWed or diffusion bonding regions of the hybrid joint. This study further explored the underlying mechanism behind the joint’s formation.

Precipitation kinetics and mechanical properties of Mg–Y–Zn and Mg–Y–Ni alloys containing long-period stacking ordered (LPSO) structures

Microstructures, mechanical properties by tensile deformation, and precipitation kinetics during elevated-temperature homogenization/aging heat treatment of Mg95.5Y3Zn1.5 and Mg95.5Y3Ni1.5 (at.%) magnesium alloys were systematically compared in the present work. The microstructure of both alloys in the as-cast state consisted of α-Mg and 18R long-period stacking ordered (LPSO) phase. For peak aging at 473 K (maximum hardness), the 18R phase in Mg95.5Y3Zn1.5 alloy partly transformed to lamellar 14H-LPSO phase, and hence, the ultimate tensile strength (UTS) and total elongation increased from 160.6 MPa to 2.6% to 210.5 MPa and 8.5%, respectively. After similar aging treatment of the Mg95.5Y3Ni1.5 alloy, the βʹ-Mg7Y particles precipitated in the structure, and as a result of precipitation hardening effect, the UTS and total elongation increased from 143.4 MPa to 1.9% to 201.6 MPa and 9.2%, respectively. It was observed that the formation of LPSO and precipitating phases during thermomechanical processing might lead to an improvement of strength-ductility synergy, for which overaging at hot temperatures might also be considered for improving plasticity and work-hardening behavior. The investigation of the formation kinetics of 14H-LPSO in Mg95.5Y3Zn1.5 alloy and βʹ-Mg7Y in Mg95.5Y3Ni1.5 alloy based on the Johnson–Mehl–Avrami–Kolmogorov (JMAK) analysis led to the activation energy (Q) of 104 kJ/mol and 89 kJ/mol, respectively. The former is similar to that of the diffusion of zinc in the matrix and the latter is close to that for the diffusion of yttrium in the matrix. Accordingly, the present work can shed light on the phase transformations and strengthening mechanisms of high-strength LPSO-containing Mg alloys.

Laser ablated uniform deposition of bismuth oxide film as efficient anode for zinc based flow battery

Zinc based redox flow batteries are the most proficient and attractive candidature for large scale energy storage applications. However, zinc dendritic formation and inhomogeneous deposition of zinc hamper the cyclability of zinc-based flow batteries. Herein, we have successfully decorated Bi2O3 on the felt by using the pulsed laser deposition (PLD) technique and tested it as a negative electrode in zinc bromine redox flow battery. The Bi2O3 felt provides more robust nucleation sites for zinc nuclei, lowers the potential of hydrogen evolution reaction, minimizes the surface diffusion of zinc, lowers zinc nucleation overpotential, and triggers homogenous zinc deposits. Compared to pristine (57.7 %), Bi2O3 felt exhibited an energy efficiency of 70.6 % at 100 mA cm−2. Interestingly, the morphological evolution of zinc deposits demonstrates that zinc deposition on the Bi2O3 felt is more homogeneous than pristine at an initial time (30 sec of charging at 20 mA cm−2). Moreover, Bi2O3 felt shows a stable long cycling performance over 200 cycles with minimized charge discharge overpotential and exhibited an avg. coulombic efficiency of 96.78 % which is superior than pristine. Thus, Bi2O3 felt is a prominent anode material for improving the electrochemical performance of zinc based redox flow batteries.

Reversible Zinc Electrodeposition at -60 °C Using a Deep Eutectic Electrolyte for Low-Temperature Zinc Metal Batteries.

Rechargeable zinc (Zn) metal batteries are attractive for use as electrochemical energy storage systems on a global scale because of the low cost, high energy density, inherent safety, and strategic resource security of Zn metal. However, at low temperatures, Zn batteries typically suffer from high electrolyte viscosity and unfavorable ion transport properties. Here, we studied reversible Zn electrodeposition in mixtures of 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([EMIm]TFSI) ionic liquid, γ-butyrolactone (GBL) organic solvent, and Zn(TFSI)2 zinc salt. The electrolyte mixtures enabled reversible Zn electrodeposition at temperatures as low as -60 °C. An electrolyte composed of 0.1 M Zn(TFSI)2 in [EMIm]TFSI:GBL with a volume ratio of 1:3 formed a deep eutectic solvent that optimized electrolyte conductivity, viscosity, and the zinc diffusion coefficient. Liquid-state 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and molecular dynamic (MD) simulations indicate increased formation of contact ion pairs and the reduction of ion aggregates are responsible for the optimal composition.

Incorporating Binary Metal Oxides in Poly(ethylene oxide)-Based Solid Electrolytes by Vapor Phase Infiltration

Vapor phase infiltration (VPI) derived from atomic layer deposition (ALD) enables inorganic materials to nucleate and grow within the free volume of polymers, which has shown promising prospects in the field of composite solid polymer electrolytes (CSPEs). However, there are only a few types of metal oxides that can be incorporated into the polymer matrix by VPI, let alone binary metal oxides, due to the limited knowledge of the VPI synthesis process. To combine the merits of different metal oxides, we investigate the VPI method to prepare ZnO-Al2O3 composites in poly(ethylene oxide) (PEO). When the introducing order is Al2O3/ZnO (AZO), due to the extremely high reactivity of trimethyl aluminum (TMA) with PEO, VPI-Al2O3 will accumulate near the surface of PEO. The surface Al2O3 layer inhibits the further diffusion of the diethyl zinc (DEZ) into the PEO matrix, leading to weak polymer-filler interactions and limited improvement of the Li+ conduction. In the incorporation order of ZnO/Al2O3 (ZAO), the moderate reactivity of DEZ renders the uniform distribution of VPI-ZnO within PEO, and the following TMA can both react with PEO and VPI-ZnO particles near the surface of PEO, which not only preserves the interactions between VPI-ZnO and PEO but also better inhibits the growth of lithium dendrites. The incorporation order plays a crucial role in the morphology and composition of binary metal oxides synthesized by VPI.

Sustainable high-energy aqueous zinc–manganese dioxide batteries enabled by stress-governed metal electrodeposition and fast zinc diffusivity

Beyond the fragile glass fiber separator, we demonstrated a polymer separator with good mechanical strength and fast Zn2+ diffusivity, which synergistically mitigates Zn dendrite formation and improves Zn reversibility at high capacity.