Zn Substitution Research Articles

Iron oxyhydroxide polytype (γ-, δ- and β-FeOOH) structures govern Zn mobility

Iron oxyhydroxide polytype minerals, such as goethite (α-FeOOH), lepidocrocite (γ-FeOOH), feroxyhyte (δ-FeOOH) and akaganeite (β-FeOOH), widely exist in terrestrial environments, and play important roles in mediating heavy metal mobility. Previous studies mainly focus on goethite, while the other three polytypes have been rarely explored. In the present work, Zn retention contents and mechanisms in Zn-coprecipitated γ-, δ- and β-FeOOH minerals were thoroughly investigated. Additionally, Zn mobility during anoxic incubation of Zn-containing lepidocrocite and feroxyhyte samples was monitored. It demonstrates that, feroxyhyte and lepidocrocite can accommodate relatively higher amounts of Zn (7.71 ± 0.20 mol% and 8.56 ± 0.22 mol% respectively) than akaganeite that retains almost no Zn (0.054 ± 0.002 mol%). In contrast, Zn has the most significant effect on akaganeite morphology. Part of total Zn is incorporated into the lepidocrocite or feroxyhyte structure by substitution for lattice Fe while the remaining Zn is adsorbed on the mineral surfaces. The different Zn substitution levels in these FeOOH minerals are greatly related with the mineral structures, that is, the ratio of edge-sharing to corner-sharing [FeO6] and thus the spatial freedom, and the pHs of the mineral synthetic solutions. During anoxic incubation in the presence of 1 mM Fe2+ at pH 6 ± 0.05 for 60 d, both Zn-containing lepidocrocite and feroxyhyte keep stable, while the dissolved Zn concentrations rapidly increase at initial stage, then decrease after reaction for 3 d, and increase again from 10 d till to the end. The final Zn release from feroxyhyte (∼98%) is much higher than that from lepidocrocite (∼30%), probably owing to the higher Fe2+-induced reductive dissolution and desorption rates, and larger amounts of Zn adsorbed on the surfaces of the former. These results help to understand the effects of Zn on the physicochemical properties of FeOOH polymorphs and the geochemical behaviors of Zn associated with Fe oxyhydroxide minerals.

Co-Electrodeposition of Metallic Precursors for Cd-Doped Cu2ZnSnS4 (CZCTS) Kesterite Absorber for Photoelectrochemical Water Splitting

Electrodeposition is widely studied in the fabrication of semiconductors for solar application, because of the low cost and easy scalability of this technique. For instance, in the last decades large effort has been dedicated to the electrodeposition of Cu2ZnSnS4 (CZTS) through different approaches, including either direct co-electrodeposition of the sulfide, the deposition of metallic alloy precursors or by stacked elemental layer, depositing Cu, Zn and Sn in sequence, then converting it into kesterite with thermal treatment in sulfur atmosphere.1–4 While being a promising alternative to CIGS (CuInGaS2), thanks to the non-toxicity and higher abundance of its constituting elements, CZTS absorbers still encounter some difficulties to their integration of high-performance solar devices. In fact, the electronic and optical properties of the material are affected by the narrow stoichiometric window acceptable for kesterite formation, inducing the segregation of secondary phases, along with the formation of lattice defects that act as recombination sites.5 A reported strategy to suppress the latter limitation is to introduce doping elements such as Ag6 and Cd7,8, partially substituting metallic atoms in the semiconductor, Cu and Zn respectively. The larger atomic radii of these elements can prevent the formation of antisite defects such as CuZn, largely increasing the semiconductor performance7. Here we propose a synthesis route of CZCTS through the co-electrodeposition of a thin film Cu-Sn-Zn-Cd alloy followed by sulfurization treatment. The deposition on SLG/Mo substrate is achieved with a sulfate-based electrolyte with citrate complexing agents and performed in three-electrode potentiostatic conditions. Proper bath formulation is designed to obtain a desirable Zn-rich, Cu-poor composition, varying the degree of Zn substitution with Cd. An alternative 2-step deposition of CuZnSn/Cd stacked precursor is also investigated, as an attempt to compensate the effect of the low H+ adsorption energy of cadmium leading to the formation of blisters in the quaternary alloy. Sulfurized samples characterization shows the formation of good quality of kesterite CZCTS, in spite of the segregation of secondary phases on the surface. Cd doping of CZTS is observed through the characteristic shift of the main kesterite XRD peak (112) and an increase of the average size of grains. The photocurrent of finalized photocathodes with structure SLG/Mo/CZCTS/CdS/Pt is measured under 10 mW/cm2 AM 1.5 radiation reporting an improvement with respect to the undoped analogue, increasing the current density at 0 V vs RHE from -5.73 to -7.18 mA/cm2 in the best case.Bibliography Colombara, D. et al. Electrodeposition of kesterite thin films for photovoltaic applications: Quo vadis? Phys. Status Solidi Appl. Mater. Sci. 212, 88–102 (2015).Ge, J. & Yan, Y. Controllable Multinary Alloy Electrodeposition for Thin-Film Solar Cell Fabrication: A Case Study of Kesterite Cu2ZnSnS4. iScience 1, 55–71 (2018).Clauwaert, K., Binnemans, K., Matthijs, E. & Fransaer, J. Electrochemical studies of the electrodeposition of copper-zinc-tin alloys from pyrophosphate electrolytes followed by selenization for CZTSe photovoltaic cells. Electrochim. Acta 188, 344–355 (2016).Jiang, F. et al. Pt/In2S3/CdS/Cu2ZnSnS4 Thin Film as an Efficient and Stable Photocathode for Water Reduction under Sunlight Radiation. J. Am. Chem. Soc. 137, 13691–13697 (2015).Polizzotti, A., Repins, I. L., Noufi, R., Wei, S. H. & Mitzi, D. B. The state and future prospects of kesterite photovoltaics. Energy Environ. Sci. 6, 3171–3182 (2013).Yuan, Z. K. et al. Engineering Solar Cell Absorbers by Exploring the Band Alignment and Defect Disparity: The Case of Cu- and Ag-Based Kesterite Compounds. Adv. Funct. Mater. 25, 6733–6743 (2015).Tay, Y. F. et al. Solution-Processed Cd-Substituted CZTS Photocathode for Efficient Solar Hydrogen Evolution from Neutral Water. Joule 2, 537–548 (2018).Su, Z. et al. Device Postannealing Enabling over 12% Efficient Solution-Processed Cu2ZnSnS4 Solar Cells with Cd2+ Substitution. Adv. Mater. 32, 1–12 (2020).

Enhanced anti-biofilm and biocompatibility of Zn and Mg substituted β-tricalcium phosphate/functionalized multiwalled carbon nanotube composites towards A. baumannii and Methicillin-Resistant Staphylococcus aureus, and MG-63 cells

In this work, Zn and Mg substituted β-tricalcium phosphate/functionalized multiwalled carbon nanotube (f-MWCNT) nanocomposites were prepared by the co-precipitation method. The structural, vibrational, morphological and biological properties of the prepared nanocomposites were studied. The structural study revealed that the increase of Zn concentration shifts the β-tricalcium phosphate planes towards higher angle. Morphological analysis confirmed the formation of hexagonal-shaped particles after substitution of Zn. The particle size of the nanoparticles decreased with the increase of Zn concentration. XPS analysis clearly showed the presence of Zn, Mg, P, Ca, O and C. The Zn (5%) rich nanocomposites have better antibiofilm activity compared to 2% of zinc substituted composite. Also, it has been proven that the prepared nanocomposites have the ability to enhance the bioactivity of commercial antibiotics by means of a decrease in drug resistance. Finally, this study acted as a pioneer to improve drug efficiency and reduced the biofilm formation of certain medically important bacteria. The in-vitro cell viability and anti-biofilm results of zinc (5%) rich nanocomposite confirmed that prepared nanocomposite has biocompatible and enhanced anti-biofilm property, which will be beneficial candidate for biomedical applications.

Effects of Group-I Elements on Output Voltage Generation of ZnO Nanowires Based Nanogenerator; Degradation of Screening Effects by Oxidation of Nanowires.

Here, we report the successful incorporation of group I elements (K, Na, Li) to ZnO nanowires. Three distinct (2, 4, and 6 wt.%) doping concentrations of group I elements have been used to generate high piezoelectric voltage by employing a vertically integrated nanowire generator (VING) structure. X-ray photoelectron spectra (XPS) indicated the seepage of dopants in ZnO nanowires by substitution of Zn. Shallow acceptor levels (LiZn, NaZn, KZn) worked as electron trapping centers for intrinsically n-type ZnO nanowires. Free moving electrons caused a leakage current through the nanowires and depleted their piezoelectric potential. Reverse leakage current is a negative factor for piezoelectric nanogenerators. A reduction in reverse leakage current signifies the rise in output voltage. A gradual rise in output voltage has been witnessed which was in accordance with various doping concentrations. K-doped ZnO nanowires have generated voltages of 0.85 V, 1.48 V, and 1.95 V. For Na-doped ZnO nanowires, the voltages were 1.23 V, 1.73 V, and 2.34 V and the voltages yeilded for Li-doped ZnO nanowires were 1.87 V, 2.63 V, and 3.54 V, respectively. Maximum voltage range has been further enhanced by the surface enrichment (oxidized with O2 molecules) of ZnO nanowires. Technique has been opted to mitigate the screening effect during an external stress. After 5 h of oxidation in a sealed chamber at 100 ppm, maximum voltage peaks were pronounced to 2.48 V, 3.19 V, and 4.57 V for K, Na, and Li, respectively. A low-cost, high performance mechanical transducer is proposed for self-powered devices.

Effect on structural, dc electrical resistivity, and magnetic properties by the substitution of Zn2+ on Co-Cu nano ferrite

XRD patterns of Zn substituted Co-Cu ferrites temperature dependence of dc electrical resistivity of Zn substituted Co-Cu ferrite nano samples. • Sol-gel auto combustion method was used for the preparation of Zn substituted Co-Cu ferrite nanoparticles. • XRD and FESEM show their single-phase cubic spinel structures. • The two absorption peaks given by FTIR at around 400–600 cm −1 wavenumber shows their single phased spinel structure. • Coercivity and saturation magnetization has almost a similar trend with concentration. They are suitable for recording media. • The DC-electrical resistivity of the considerable number of samples shows the semiconducting nature. This nature is due to the hopping mechanism. Zn 2+ substituted Co-Cu ferrite ( Co 0.5 Cu 0.5-x Zn x Fe 2 O 4 where x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5) nanoparticles were synthesized from sol-gel auto-combustion approach. A cubic structure was found with the study of XRD and FESEM. The linear growth of lattice constant from 8.384 to 8.409 Å was observed by Zn 2+ substitution from 0 to 0.3. With the increase in Zn 2+ ion content, the average crystallite size increases from 30 nm to 45 nm. FTIR shows their absorption peaks at 435–412 cm −1 , characteristic of the spinel crystal structure. The magnetic saturation of 86.35 emu/g with the Zn 2+ substitution shows their superparamagnetic nature. The coercivity (Hc ) values vary from 112 Oe to 415 Oe. These values make the investigated samples well suited for their use in recording media. The two probe’s DC electrical resistivity kit within 370–580 K follow the Polaron hopping model resulting in their semiconducting nature. The activation energies of 0.30–0.50 eV are found with the help of the resistivity temperature plot.

Over 10% Efficient Cu2CdSnS4 Solar Cells Fabricated from Optimized Sulfurization

AbstractAt present, Kesterite‐based thin‐film solar cells, such as Cu2ZnSnS4 solar cells, involve serious band‐tailed states, which leads to low open‐circuit voltage, thereby hindering the further improvement of device performance. In stannite‐based materials, such as Cu2CdSnS4, the substitution of Zn with Cd can effectively suppress CuCd‐related point defects and defect clusters; thus, the band‐tailing state is few, which has attracted considerable research attention. In this work, on the basis of using optimized sulfurization and optimizing ratios (Cu/Cd+Sn) and temperatures, Cu2CdSnS4 thin films can be obtained with good quality and single‐phase composition, in which the device prepared at a ratio of 0.83 and 590 °C has the highest efficiency. Defect analysis shows that the substitution of Zn with Cd can effectively reduce CuCd‐related defects and defect clusters (such as 2CuCd+SnCd) and also decrease Urbach energy, fluctuations of bandgap, and electrostatic potential compared with kesterite‐based devices. In particular, Cu2CdSnS4 thin‐film solar cell prepared under optimized conditions (the ratio of 0.83 and 590 °C) has the minimum reverse saturation current, red shift, and the maximum minority carrier diffusion length. Therefore, an efficiency over 10% Cu2CdSnS4 thin‐film solar cell is reported, which shows the highest efficiency among stannite‐based solar cells to date.

Effect of atomic substitution on the sodium manganese ferrite thermochemical cycle for hydrogen production

This work presents the effect of atomic substitution on the MnFe2O4–Na2CO3 thermochemical cycle for H2 production. The non-oxidative decarbonation/carbonation reaction of the MnFe2O4–Na2CO3 mixture is investigated as the starting reference. Repeated cycling results in a 30% loss of reversibility due to an overall reduction of the reactive interfaces. The substitution of Na2CO3 for Li2CO3 decreases the decarbonation onset temperature by about 100 °C, but almost no reversibility is observed during the cycles due to the irreversible Li+ intercalation. The effect of partial Mn substitution for Ca, Ni, and Zn is presented. The 5% Zn mixture shows the best decarbonation/carbonation reversibility and is tested for H2 production together with MnFe2O4–Na2CO3. The reference mixture produces more H2 during the first cycle (≈1.1 vs. 0.7 mmol/g), but its production drastically drops by two orders of magnitude upon cycling and becomes negligible after 5 cycles. By contrast, the Zn-doped mixture exhibits a stable H2 production of 0.22 mmol/g with no decreasing trend observed from cycle 2 to cycle 5. As result, in the fifth cycle, the Zn-doped mixture produces 23 times more H2 than MnFe2O4–Na2CO3. Thermogravimetry and X-ray diffraction confirm that doping with Zn significantly improves the regeneration of the reactants.

Effect of Zn substitution on the AC induction heating properties of ZnxMn1-xFe2O4 (x = 0.1–0.9) nanoparticles prepared using microwave assisted synthesis

ZnxMn1-xFe2O4 (x = 0.1–0.9) magnetic nanoparticles (MNPs) were prepared using a microwave-assisted coprecipitation method, and the effect of Zn substitution on the AC induction heating properties of the MNPs was investigated. With increasing Zn substitution, owing to the lower solubility product of Zn2+ ions, the formation of new nuclei was preferred over grain growth, which reduced the average crystallite size. The saturation magnetization initially increased with Zn substitution, attained the maximum value at x = 0.5, and decreased beyond that due to Yafet-Kittel type triangular spin ordering. The prepared MNPs exhibited superparamagnetic behaviour at ∼ 300 K. AC induction heating studies of the MNPs indicated a specific absorption rate of ∼ 130 ± 4 W/gFe at x = 0.1. The AC induction heating efficiency did not exhibit any non-monotonic variation at x = 0.5, and progressively decreased with increasing Zn concentration. This was attributed to the reduction in the MNP size and anisotropy energy density at higher Zn concentration that caused the relaxation dynamics to be Nèel dominated with lower effective relaxation time. AC induction heating studies on the agar-immobilized samples confirmed the Brownian relaxation mediated magneto-thermal energy conversion at lower Zn concentration. The obtained results demonstrated that saturation magnetization alone does not influence the AC induction heating efficiency and relaxation dynamics play a significant role.

Computational study of hyperfine interaction for Zn substitute Ga in β-Ga2O3

By using a gap-optimized, Koopmans-compliant hybrid functional, we investigate Zn at Ga sites in β-Ga2O3. In this study, we found that besides acting as a deep acceptor, ZnGa can also trap another hole to form a donor state. Our calculated results show the Zn substitution at the octahedral Ga site (ZnGa2) is slightly more favorable than at tetrahedral site (ZnGa1). This result is in agreement with the previous experimental study [Journal of Applied Physics 129, 155701 (2021)]. At the neutral charge state of ZnGa, a hole is trapped at an adjacent tetrahedral O site in a small polaron state for both ZnGa1 and ZnGa2. The calculated hyperfine interaction between these trapped-holes and neighbors Ga atoms are in good agreement with the experimental measurements.

Hole Concentration Reduction in CuI by Zn Substitution and its Mechanism: Toward Device Applications.

Copper iodide (CuI) is a promising p-type transparent semiconductor with excellent carrier mobility. However, the high hole concentration in conventionally fabricated CuI including the single crystal hinders its applicability to the channel layer of thin-film transistors. We found that Zn substitution into Cu+ sites can effectively reduce the hole concentration. Experimental and computational examinations showed that the dominant mechanism involved the formation of a defect pair, the Zn-substituted Cu site (ZnCu) and Cu vacancy (VCu), and the simultaneous suppression of VCu arising from the stabilization of Cu+ in the Zn-substituted CuI lattice, rather than hole compensation by the electrons generated from Zn2+ substitution into Cu+ sites. Our results show that the hole concentration of Zn-substituted CuI is tunable in the range of 1014-1018 cm-3, making it suitable for thin-film transistors and hole transport layers in OLEDs.

High thermoelectric performance in p-type InSb with all-scale hierarchical architectures

We realize the switch of InSb from its intrinsic n-type to p-type semiconductor nature through the substitution of Zn for In. Then, to reduce the high thermal conductivity of p-type InSb, MnO2 is added into p-type InSb matrix. A solid reaction between the MnO2 additives and InSb matrix takes place during spark plasma sintering process. By this approach, the point defect MnIn+, nanoscale In2O3 precipitates, and microscale MnO2 and Sb secondary phases are formed in InSb. Such all-scale hierarchical architectures play a critical role in the suppression of phonon transport, realizing a low lattice thermal conductivity of 1.50 W/m/K at 733 K for Zn0.04In0.96Sb + 3 wt.% MnO2, 58% lower than that of ZnxIn1-xSb. Meanwhile, the Zn0.04In0.96Sb + 3 wt.% MnO2 maintains excellent electrical properties (i.e., power factor ∼ 21 μW/cm/K2 at 733 K). Eventually, the thermoelectric figure of merit ZT of Zn0.04In0.96Sb + 3 wt.% MnO2 material reaches 0.54 at 733 K, which is comparable to the well-established peak ZT of n-type InSb at the same temperature, showing promising potential in thermoelectric power generation.

Effects of Zinc Methionine Hydroxy Analog Chelate on Laying Performance, Serum Hormone Levels, and Expression of Reproductive Axis Related Genes in Aged Broiler Breeders.

Inorganic zinc (Zn) supplements are commonly used in poultry feeds, but their low utilization results in the increase of Zn excretion. Thus, to provide a new perspective for the substitution of inorganic Zn, a novel Zn methionine hydroxy analog chelate (Zn-MHA) was studied in the present study to evaluate its effects on laying performance, serum hormone indexes and reproductive axis-related genes in broilers breeders. A total of 480 Hubbard breeders (56-week-old) were fed a basal diet (containing 27.81 mg Zn/kg) without Zn addition for 2 weeks, and then allocated to 4 groups with 6 replicates (each replicate consisting of 10 cages and 2 breeders per cage) for 10 weeks. Four treatment diets given to broiler breeders included the basal diet added with 25, 50, and 75 mg/kg of Zn-MHA and 100 mg/kg of Zn sulfate (ZnSO4). The laying rate, egg weight and feed conversation ratio increased in the 75 mg/kg Zn-MHA group compared to the ZnSO4 group. The eggshell thickness was not decreased with the addition of 50 mg/kg and 75 mg/kg Zn-MHA in the diet compared to the 100 mg/kg ZnSO4 group. There was a significant improvement in the reproductive performance of breeders in the 75 mg/kg Zn-MHA group, including the fertility and 1-day-old offspring weight. Besides, serum sex hormone levels including FSH and P4 increased significantly in 75 mg/kg Zn-MHA group. No significant effect on the ovarian weight or the number of follicles in broiler breeders was observed by supplementing Zn-MHA. Compared to the 100 mg/kg ZnSO4 group, dietary supplementation with 75 mg/kg of Zn-MHA showed an up-regulation of the FSHR mRNA in the granular layer of follicles. However, dietary supplementation of Zn-MHA had no effects on mRNA expressions of the ovarian LHR and PRLR genes. These findings reinforce the suggestion that Zn-MHA (75 mg/kg) could replace ZnSO4 (100 mg/kg) as a Zn supplement in diet of broiler breeders, which resulted in better laying and reproduction performances by regulating the expression levels of reproductive axis related genes and serum hormone levels.

Enhanced magnetocaloric effect from Zn substitution in perovskite Eu(Ti,Zn)O3 compounds

The magnetic transition from antiferromagnetism to ferromagnetism (AFM-FM) in EuTiO3 provides the feasibility of regulating its magnetic properties. Foreign element substitution has been proved to be an effective way to achieve AFM-FM switching and enhanced magnetocaloric effect (MCE) in EuTiO3 system. In this study, a series of Zn substituted Eu(Ti,Zn)O3 perovskites were synthesized, the crystal structure, magnetic properties, and MCE were investigated. All the compounds crystallize in a pure cubic perovskite phase with the space group Pm3m, and undergo a second-order phase transition at the ordering temperature 6.0 K. The substitution of Zn can significantly regulate the magnetic properties and enhance the ferromagnetic coupling, thus leading to an enhanced MCE in the Eu(Ti,Zn)O3 compounds. Under field change of 0–1, 0–2, and 0–5 T, the −ΔSMmax values are 10.3, 21.4, and 38.5 J·kg−1·K−1 for EuTi0.9375Zn0.0625O3, 10.8, 22.7, and 41.1 J·kg−1·K−1 for EuTi0.875Zn0.125O3, 12.5, 25.3, and 45.0 J·kg−1·K−1 for EuTi0.8125Zn0.1875O3, respectively. Besides, the compounds exhibit prominent refrigeration capability and temperature averaged entropy change. The considerable magnetocaloric performances make the Eu(Ti,Zn)O3 perovskites potential candidate materials for cryogenic magnetic refrigeration.

A novel CaCu2.8-xZnxTi4O12 system: a high-performance dielectric with nonlinear J − E properties

Colossal dielectric constants (ε′∼11,550 – 15,535) with very low dielectric loss (tanδ ∼0.013 – 0.033) at 30 °C and 1 kHz were achieved in CaCu2.8-xZnxTi4O12 (x = 0.00 – 0.10) ceramics sintered at 1100 °C for 8 and 12 h. Nonlinear J-E behaviors were observed in these ceramics with an extremely high nonlinear coefficient (α) of ∼10.14 in CaCu2.75Zn0.05Ti4O12 sintered for 12 h. Additionally, a breakdown electric field (Eb) was found to increase in samples with a high Zn2+ ion content. To reveal these excellent properties, the phase and microstructure of these materials were explored using XRD and FE-SEM. Elemental mapping and EDXS spectra confirmed the presence of TiO2 and CaTiO3 minor phases with Zn2+ ions in the main CaCu3Ti4O12 phase. Improved dielectric properties and nonlinear J-E behaviors are discussed based on the increased grain boundary resistance (Rgb) due to the presence of minor phases and substitution of Zn2+ ions at the Cu2+ sites of CaCu2.8-xZnxTi4O12. The XPS results confirmed that electrons could hop at the Cu+− O − Cu2+ and Cu3+− O − Cu2+ sites, indicating the presence of semiconducting grains in these ceramics.

Magnetic Study of BiPbSrCaCuZnO Super Conducting thin film Synthesized by pulsed Laser Deposition (PLD) Method

In this research, the effect of transition metal Zn doping to Bi PbSrCaCuO were studied. Various weight ratio (0.2, 0.4, 0.6, 0.8, and 1) of Zn to BiPbSrCaCuO were prepared by using pulsed laser deposition Method (PLD). The effect of Zn doping to BiPbSrCaCuO were examined using a variety of characterization techniques, X-ray diffraction and vibrating sample magnetometer (VSM) this examination was done in the Islamic republic of Iran at University of Tehran. The XRD, reveals that Zn-doped BiPbSrCaCuO film crystallizes in tetragonal structure with mixture of two phases 2212 and 2223. The high phase 2223 increase with increasing Zn dopant especially was found higher at (Zn= 0.6, 0.8). The electrical properties of undoped and doped samples, were measured by four probe technique, the phase transition from normal resistivity to absence resistivity occurring at temperature called critical temperature Tc the values of TC for variable Zn substitution in BiPbSrCaCuO recorded (97, 90, 95, 102) and super conducting behavior. The saturation magnetization (MS) was found higher for undoped as compared to doped samples.

Copper Substitution in P2-Type Sodium Layered Oxide To Mitigate Phase Transition and Enhance Cyclability of Sodium-Ion Batteries.

Development of high-performance cathode materials is one of the key challenges in the practical application of sodium-ion batteries. Among all the cathode materials, layered sodium transition-metal oxides are particularly attractive. However, undesired phase transitions are often reported and have detrimental effects on the structure stability and electrochemical performance. Cu substitution of zinc in the P2-type Na0.6Mn0.7Ni0.15Zn0.15-xCuxO2 (x = 0, 0.075, and 0.15) composites was investigated in this study for mitigating the biphase transition and enhancing the electrochemical performance of sodium-ion batteries. The coupling effect of Zn and Cu enables an excellent capacity retention of 96.4% of the initial discharge capacity after 150 cycles at 0.1 C in the Na/Na0.6Mn0.7Ni0.15Zn0.075Cu0.075O2 cell. The biphase transition that occurred in the high voltage range has been significantly suppressed after the incorporation of Cu in Na0.6Mn0.7Ni0.15Zn0.15O2, which was confirmed by in situ X-ray diffraction studies. Moreover, the substitution of the inert element Zn with electrochemically active Cu leads to the suppression of anionic redox and the occurrence of Cu2+/3+ redox reaction, and the electrolyte decomposition is impeded after the introduction of electrochemically active Cu in the Na0.6Mn0.7Ni0.15Zn0.15-xCuxO2 composite cathode. The enhanced electrochemical performance in the Na0.6Mn0.7Ni0.15Zn0.075Cu0.075O2 electrode can be ascribed to the coexistence of Zn and Cu and alleviated volumetric change as well as suppressed electrode/electrolyte side reaction after Cu substitution.

Changes in the Structural Parameters and Effective Magnetic Moment of Eu2−xCexCuO4+α−δ by Zn Substitution

The effect of nonmagnetic Zn impurities on the structural parameters and effective magnetic moment of electron-doped superconducting cuprates Eu2−xCexCu1−yZnyO4+α−δ (ECCZO) with x = 0.10 and 0.15 and y = 0 and 0.01 has been investigated using XRD and SQUID measurements. From XRD measurements, it is found that the lattice parameter of c and the Cu-O bond length increase with increasing y. The crystallite size of ECCZO samples was relatively smaller than the sample without impurities determined by the Debye–Scherrer equation and the W-H Plot method. Changes in the lattice parameters of c and Cu-O bond length can affect the appearance of superconductivity (Tc). The smaller the value of the lattice parameter of c and the Cu-O bond length causes the distance between the conducting layer and the charge reservoir to be close enough so that the charge transfer process becomes easier. From the magnetic susceptibility measurement, paramagnetic characteristics were observed for samples with x = 0.10. Meanwhile, for samples with x = 0.15, diamagnetic characteristics can be identified in sample with y = 0. The onset of Tc was observed around 11 K, as indicated by a change from paramagnetic to diamagnetic characteristics. The superconductivity phase disappears with y = 0.01. The effective magnetic moments in samples with y = 0 are smaller than those in samples with y = 0.01. The effective magnetic moment in ECCZO can be contributed by Cu2+. When the amount of Cu2+ decreases due to the addition of nonmagnetic Zn2+ atoms, the overall effective magnetic moment value also decreases. Another possibility that causes a decrease in the value of the magnetic moment of the ECCZO is the existence of stripe-pinning model, which results in suppressed superconductivity by Zn.

Effect of Zn Substitution on the Structural, Optical Properties and Photocatalytic Activity of BiFeO3 Nanopowders

The multiferroic Zn‐doped BiFeO3 materials with nominal formula (0 ≤ x ≤ 0.08) are successfully synthesized using hydrothermal synthesis allowing to obtain powders with an average grain size of 8 nm. X‐ray diffraction and Raman spectroscopy analysis prove that nanopowders are pure and homogeneous and show an increase of the unit cell volume when the amount of Zn increases attesting of the substitution of Fe site. Using temperature‐dependent Raman spectroscopy, it is also found that the Néel antiferromagnetic critical temperature is weakly, if any, affected. In contrast, using UV–vis reflectance measurements, clear changes are observed in the features of the optical absorption with modifications of the crystal‐field when increasing the Zn amount. The photocatalytic activity of the pure and the most doped samples is evaluated by the degradation of the methylene blue dye under visible light irradiation. The photocatalytic activity of the Zn‐doped samples is found to be higher than that of BiFeO3. After 3 h of sunlight irradiation, the degradation efficiency increases from 61% to 83% for BiFeO3 and BiFe0.92Zn0.08O3, respectively. The crystal‐field modification after Zn substitution is considered as the principal cause of the obvious enhanced photocatalytic activity.

Effect of Varying Doping Level on Structural, Electrical and Optical Properties of Al Doped ZnO Spin Coated Films

The synthesis and characterization of spin-coated Al-doped ZnO (AZO) thin films with varying Al concentrations (0%, 5%, 10%, 15% and 20%) onto glass substrates have been demonstrated in this paper. The structural, electrical and optical properties of the spin-coated thin films have been investigated by Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray (EDX) analysis, Van Der Pauw method and UV-visible spectroscopy. The EDX study shows well-defined peaks which confirm the presence of only Zn, O and Al and no other impurities in the films. The increase of Al and decrease of Zn weight percentages with increasing doping level confirms the effective substitution of Zn by Al. SEM of the surfaces of the films shows that undoped ZnO films contain particle agglomeration which is reduced with Al doping and the surfaces of the films gradually became more uniform. The thickness of the AZO films varied from 86 to 699 nm with increasing Al doping concentration. The electrical conductivity of the films increased up to ~ 7 × 10-2 (Ω.cm)-1 due to doping with 5% Al concentration. The optical transmittance highly increased above 95% in the visible range with the introduction of Al dopant and it kept rising with the increase of Al concentration. The optical energy band gap of undoped ZnO increased from 3.275eV to 3.342 eV with 5% Al doping.

Electrical responses and dielectric properties of (Zn2+ + F−) co–doped CaCu3Ti4O12 ceramics

The effects of Zn2+ and F− ions on the ceramic microstructure, electrical properties, and colossal dielectric response of CaCu3Ti4O12 were investigated. The dopants influenced the microstructure of the CaCu3Ti4O12. The replacement of Zn2+ and F− ions reduced the low–frequency loss tangent while retaining the high dielectric constant of CaCu3Ti4O12. In co–doped ceramics, the high dielectric permittivity of around 5.76 – 7.59 × 104 and low loss tangent of 0.082 – 0.085 can be attained. The decrease in the loss tangent of the co–doped ceramic samples is commensurate with the significant increase in the grain boundary (GB) resistance and breakdown electric field. The Cu+ and Ti3+ ions in CaCu3Ti4O12 were identified using X–ray photoelectron spectroscopy and were found to be decreased by co–doping with Zn2+ and F−. The presence of these ions may play a crucial role in the semiconducting grains. The substitution of Zn2+ and F− ions can increase the electrostatic potential barriers at the GBs, resulting in improved GB resistance.