Zn Substitution Research Articles

Unveiling the impact of Cd and Zn substitutions on the structural, mechanical, electronic, and optical properties of SrS: A first principles analysis

This study employs ab-initio calculations based on density functional theory (DFT) to comprehensively investigate the multifaceted effects of Cd and Zn substitutions on the structural stability, mechanical behavior, electronic characteristics, and optical properties of SrS alloy. Structural analysis unveils a marginal reduction in lattice parameters for both doped compounds, signifying a subtle influence on the crystalline structure. Mechanical evaluation reveals that SrS and Sr0.75Cd0.25S keep their intrinsic brittleness, whereas the inclusion of 25 % Zn imparts a subtle ductile nature. The conservation of rigidity is observed post-doping, albeit with anisotropic features and differing degrees of stiffness among the compounds. Investigating electronic properties, the band gap of Sr0.75Cd0.25S persists as an indirect transition between M and Γ points, mirroring SrS's behavior. In contrast, a remarkable transformation is noted with 25 % Zn doping, shifting SrS to a direct band gap semiconductor. Interestingly, Cd and Zn incorporation leads to a band gap reduction, suggesting potential avenues for tuning the material's electronic behavior. Dielectric constant analyses unravel intriguing phenomena. The binary compound exhibits Mie resonance across the visible-infrared spectrum, a feature that contracts to the infrared range after doping. This nuanced shift has direct implications on the material's interaction with incident light and its resulting optical properties. Evaluation of the refractive index, absorption coefficient, reflectivity, and optical conductivity demonstrates a striking resemblance in the optical behavior of Sr0.75Zn0.25S and Sr0.75Cd0.25S to the pristine SrS alloy.

Theoretical Study of the Multiferroic Properties of Ion-Doped CaBaCo4O7

Using a microscopic model and Green’s function theory, we investigated the magnetization, specific heat, and polarization properties of CaBaCo4O7 (CBCO), scrutinizing their variations with temperature, magnetic field strength, and doping effects. Our analysis revealed a conspicuous kink in the specific heat curve near the critical temperature (TC), indicative of a phase transition. Additionally, the observed increase in polarization, P with escalating magnetic field strength serves as compelling evidence for the multiferroic nature of CBCO. Substituting Co ions with Fe ions resulted in an augmentation of the CBCO magnetization, M, while doping with Zn, Mn, or Ni ions led to a decline. Similarly, doping CBCO with Y or Sr ions at the Ca site exhibited divergent effects on magnetization, M, with an increase in the former and a decrease in the latter case. This modulation of the magnetization, M, can be attributed to the varying strains induced by the doping ions, thereby altering the exchange interaction constants within the system. The polarization, P, increases by Ni, Mn, or Zn substitution on the kagome layer Co sites. It can be concluded that Ni, Mn, or Zn doping enhances the magnetoelectric effect of CBCO. Notably, our findings align qualitatively well with experimental observations, reinforcing the validity of our theoretical framework.

Blue pigment based on Ni-doped Zn2GeO4: Addressing structure and electronic properties by combining experiment and theory

Understanding the process of color development and creating practical and efficient blue pigments is crucial in ceramics. The current work describes the synthesis and characterization of Ni2+-doped Zn2GeO4 samples with varying concentrations (x = 0, 0.01, 0.02, 0.04, 0.08 and 0.16 mol%) as an effective strategy for tailoring their structure and electronic properties. These materials were synthesized using the coprecipitation method followed by microwave-assisted hydrothermal treatment at 140 °C for 10 min, and the as-synthesized samples underwent heat treatment at 1000 °C for 2 h to establish thermal-colorimetric stability. The synergistic effect of the Ni2+ 3d orbitals generating energy levels as new trapping sites in a broad energy range above the valence band was verified using DFT calculations. The substitution of Zn2+ by Ni2+ at x = 0.01 % changes the local electronic structure, resulting in a switchable electron transfer from the [NiO4] and the neighbor [ZnO4]and [GeO4] tetrahedral clusters to shared oxygen anions, which is responsible for the observed blue color, as confirmed by colorimetric and spectroscopic analysis. This study paves the way, shedding light on the strategic design of a new class of ceramic pigments characterized by low toxicity, a vibrant blue hue, and excellent chemical/thermal durability. Furthermore, it provides a robust platform for exploring its potential application in the color-tunable Zn2GeO4-based materials.

Mn- or Zn-substituted goethite enhancing tetracycline degradation by increasing oxygen vacancies and promoting electron transfer

The metal-substituted goethite with addition of oxidants can effectively promote the degradation of antibiotics, but the usage of external agents restricts its application in in-situ remediation of antibiotic pollution. In this study, the metal-substituted goethites were prepared through co-precipitation method to investigate the effects of using manganese (Mn) or zinc (Zn) substitution alone on tetracycline (TC) degradation, combining with microscopic characterization and electrochemical methods. The results showed that the degradation rate constants of the first stage on Mn or Zn-substituted goethite were 0.299 h-1 and 0.498 h-1, respectively, which were about 2 and 4 times of the pristine goethite (0.117 h-1). In the pH range of 4.0–9.0, Mn or Zn substitution significantly promoted TC degradation. Free and non-free radical pathways existed in the process of TC degradation by Mn or Zn-substituted goethite. The active site change and enhanced electron transfer ability were the main reasons for promoting degradation. Mn or Zn substitution increased oxygen vacancy (OV) content and promoted the electron transfer between TC and goethite. In Zn-substituted goethite, the coupling of OV and electron transfer produced free radicals, and in Mn-substituted goethite, the redox reaction induced mainly by electron transfer produces free radicals. This study reveals a new mechanism of efficient degradation of TC by iron minerals without the need for external oxidants, and the materials studied can be used for in-situ remediation of antibiotic contaminated groundwater.

Boosting peroxymonosulfate activation over partial Zn-substituted Co3O4 for florfenicol degradation: Insights into catalytic performance, degradation mechanism and routes

Florfenicol (FLO) is a broad-spectrum halogenated antibiotic (containing F and Cl atoms), and the discharged FLO in wastewater exhibits potential biotoxicity. Peroxymonosulfate (PMS) activation can generate reactive oxygen species (ROSs) to realize efficient degradation of organic pollutants. Herein, Zn-substituted Co3O4 (ZnxCo) catalysts were prepared and applied in PMS activation for FLO degradation. The physicochemical properties were systematically studied by combining experiments and density functional theory (DFT) calculation. The Zn partial substitution induced electron rearrangement and promoted oxygen vacancy (OV) formation in Co3O4. Zn0.03Co catalyst exhibited superior FLO removal, achieving a higher reaction rate of 0.112 min−1 than Co3O4 (0.053 min−1). The FLO degradation was highly dependent on the factors of PMS/Zn0.03Co/FLO dosage, temperature, initial pH, and coexisting inorganic anions. The Zn0.03Co also displayed outstanding performance in PMS activation for degradation of various typical organic pollutants. Electron paramagnetic resonance (EPR) spectra and quenching experiments indicated that both radical species (·OH, SO4·-, and ·O2-) and nonradical species (1O2) contribute to FLO removal. The redox cycle of Co3+/Co2+ and OVs played an essential role in PMS activation. The electron structure of FLO and parameters of PMS adsorbed on ZnxCo were calculated. The longer length of CoO and OO bonds for the adsorbed PMS could enhance its activation to generate ROSs. The intermediates were detected, and five degradation pathways were proposed. The acute and chronic toxicities of intermediates suggested that the dechlorination process is important for the toxicity attenuation of FLO. This study clarified the performance enhancement mechanism of Zn substitution on FLO degradation by PMS activation using Co3O4 based catalyst, which favors the development of PMS-based advanced oxidation processes for wastewater treatment.

Charge transport and extrinsic absorption of two-dimensional defect-rich ZnIn2S4 semiconductor for below-bandgap photodetection

As a rediscovered ternary two-dimensional (2D) material, defect-rich Znln2S4 has great potential for energy-harvesting applications. However, the effect of defects on its physical properties and device performance remains elusive. Herein, we explored the influence of defects (S vacancies and In–Zn substitutions) in few-layer Znln2S4 on the charge transport and photoelectric performance. It is demonstrated that the defect-rich Znln2S4 device exhibits two-dimensional variable range hopping transport mechanism, with uniform charge transport along the channel and low contact resistance at the electrical contacts of Znln2S4/Au. Importantly, due to the contribution of the donor and acceptor energy levels inside the bandgap, the flake exhibits pronounced extrinsic absorption, leading to the competitive photodetector performance under sub-bandgap photo-excitation. Explicitly, the device exhibits a maximum responsivity of 4.08 × 104 A W−1, a photo-gain of >108 electrons per photon, and a specific detectivity of ∼1015 Jones under 532 nm laser excitation, with detection wavelength extending from 400 to 980 nm. Our findings underscore the significant potential of defect-engineering to enrich the functionalities of 2D semiconductors.

Upconversion luminescence and temperature sensing performance of Zn2+-doped Ba2GdAlO5: Yb3+, Er3+ phosphors

Although upconversion luminescence (UCL) materials have attracted considerable attention in biomedical, lighting, anti-counterfeiting, and solar cells due to their excellent fluorescence properties, reports of the dibarium gadolinium aluminum oxide (Ba2GdAlO5) are scarce. Herein, we synthesized the single-phase Ba2GdAlO5 material with non-stoichiometric Ba2Gd1.06Al0.94O5 (denoted as BGAO, hereafter). The X-ray Rietveld refinement reveals that the substitution of Gd for Al accounts for the non-stoichiometry. Notably, the UCL properties of BGAO are realized by doping with Yb3+ and Er3+ ion pair, and it can be further enhanced significantly by co-doping with appropriate Zn2+ ions. The SEM images show that the particle size increases as the concentration of Zn2+ ions increases. The X-ray Rietveld refinement results of the Zn-doped BGAO: 0.1 Yb3+, 0.03Er3+ phosphor indicate the substitution of Zn2+ for Ba2+ and Al3+ ions simultaneously. Grain growth and lattice distortion account for the improvement of UCL properties after Zn2+ ions doping. In addition, the temperature sensing performance of the Zn2+-doped sample has been researched based on the fluorescence intensity ratio (FIR) technique, and the maximum absolute and relative sensitivities (SA-max and SR-max) are obtained to be 4.8 × 10−3 K−1 at 498 K and 1.1% K−1 at 298 K, respectively. This work provides a candidate with high UCL intensity for potential applications in optical temperature sensors.

A Ce-CuZn catalyst with abundant Cu/Zn-OV-Ce active sites for CO2 hydrogenation to methanol

CO2 hydrogenation to chemicals and fuels is a significant approach for achieving carbon neutrality. It is essential to rationally design the chemical structure and catalytic active sites towards the development of efficient catalysts. Here we show a Ce-CuZn catalyst with enriched Cu/Zn-OV-Ce active sites fabricated through the atomic-level substitution of Cu and Zn into Ce-MOF precursor. The Ce-CuZn catalyst exhibits a high methanol selectivity of 71.1% and a space-time yield of methanol up to 400.3 g·kgcat−1·h−1 with excellent stability for 170 h at 260 °C, comparable to that of the state-of-the-art CuZnAl catalysts. Controlled experiments and DFT calculations confirm that the incorporation of Cu and Zn into CeO2 with abundant oxygen vacancies can facilitate H2 dissociation energetically and thus improve CO2 hydrogenation over the Ce-CuZn catalyst via formate intermediates. This work offers an atomic-level design strategy for constructing efficient multi-metal catalysts for methanol synthesis through precise control of active sites.

Investigation of Zinc and Chromium Substitution Nickel-rich LiNi1−x−yZnyCrxO2 Cathode Materials to Improve the Redox Reaction of Lithium-ion Battery: A First-principles Study

First-principles calculations are employed to investigate the structural, electronic, magnetic, thermoelectric, and electrochemical characteristics of Nickel-rich layered cathodes by substitution of Zn and Cr such as LiNi1−x−yZnyCrxO2 (with x = 0.00, 0.16 and 0.32, y = 0.00 and 0.16). The structure of pure LiNiO2 and substituted are organized in a trigonal arrangement inside the P3m1 space group. Using PBE-GGA approximation, the spin-polarized calculation of pure LiNiO2 in a spin-down channel exhibits a band gap of 0.48 eV. Whereas, Zn and Cr substitution results in the band gap reduction to zero, and metallic behavior is observed. Electronic charge density calculation Ni(Zn, Cr)-O reveals covalent bonding. In electrochemical investigation, by the increasing substitution concentration of Zn and Cr in LiNi1−x−yZnyCrxO2 significant improvements are observed at 4.65–3.89 V potential with a good theoretical discharge capacity of 48–246 mAhg−1. The exchange constants N∘α and N∘β demonstrate negative values that validate the ferromagnetic nature of substituted material. The thermoelectric parameters have been determined using the BoltzTraP code and the highest ZT value of 0.35 is obtained for LiNi0.52Zn0.16Cr0.32O2. These results offer a new perspective on the potential of doping techniques for Nickel-rich cathode materials, providing helpful insight for the development of high-performance cathodes for Lithium-ion battery applications.

Green sol-gel synthesis using Moringa oleifera gum and modified structural, magnetic and optical properties of Co-Zn aluminates

The Co1-xZnxAl2O4 spinel (x = 0, 0.25, 0.5, 0.75 and 1) was synthesized using Moringa oleifera gum by the sol-gel chemical route. The characterization of the investigated samples was performed by TG-DTA, XRD, XPS, FTIR, FESEM, and VSM techniques. The XRD pattern reveals cubic spinel structure with space group Fd3̅m and a good crystallinity. Lattice parameter values linearly increase with increase in Zn concentration. The EDAX spectrum confirms purity of the prepared samples with nonexistence of the elements other than Co, Zn, Al and O. The FTIR spectrum confirms the cubic spinel structure of the aluminates. Magnetic studies showed that the saturation magnetization, as well as the coercivity of the investigated samples, is decreasing with the increasing Zn substitution. The band gap energies obtained from the UV vis absorption spectra are increasing due to phase purity and systematic variation of the lattice parameter. Moreover, the values of band gap energies suggest the possible use of the aluminates as the optical and photoluminescence materials.

Synthesis and influence of Zn substitution on optical and magnetic properties of cobalt ferrite nanoparticles by a polyacrylamide gel route

Synthesis and influence of Zn substitution on optical and magnetic properties of cobalt ferrite nanoparticles by a polyacrylamide gel route

Cationic migration effect on the dielectric and magnetic properties of CoFe2O4/ZnO composites

The present paper focusses on the effect of cationic migration in the sintered CoFe2O4/ZnO composite. The increase in lattice parameter of the CoFe2O4 after sintering indicates substitution of Zn. Mӧssbauer analysis of the samples indicates the transformation of composites to paramagnet in the sample sintered at 600 and 750 °C. At 900 °C, a low hyperfine field sextet was evolved complimented by MH loop which is due to redistribution of cations and formation of ferromagnetic phase. Maxwell-Wagner dispersion was identified by the frequency-dependent fluctuation of dielectric constants (ε׳) and dielectric loss (tan δ). Dielectric constant values of 8.66, 7.90, 9.31 and dielectric loss value of 0.11, 0.03, 0.05 were found for CZ6, CZ7 and CZ9 respectively at 1 MHz frequencies. The composite are suitable for high frequency applications due to its low loss, high resistance, low sintering temperature. The mechanisms behind these observations are discussed in this paper.

Exceptional Thermoelectric Performance of Cu2(Zn,Fe,Cd)SnS4 Thin Films.

High-quality Cu2(Zn,Fe,Cd)SnS4 (CZFCTS) thin films based on the parent CZTS were prepared by aerosol-assisted chemical vapor deposition (AACVD). Substitution of Zn by Fe and Cd significantly improved the electrical transport properties, and monophasic CZFCTS thin films exhibited a maximum power factor (PF) of ∼0.22 μW cm-1 K-2 at 575 K. The quality and performance of the CZFCTS thin films were further improved by postdeposition annealing. CZFCTS thin films annealed for 24 h showed a significantly enhanced maximum PF of ∼2.4 μW cm-1 K-2 at 575 K. This is higher than all reported values for single-phase quaternary sulfide (Cu2BSnS4, B = Mn, Fe, Co, Ni) thin films and even exceeds the PF for most polycrystalline bulk materials of these sulfides. Density functional theory (DFT) calculations were performed to understand the impact of Cd and Fe substitution on the electronic properties of CZTS. It was predicted that CZFCTS would have a smaller band gap than CZTS and a higher density of states (DoS) near the Fermi level. The thermal conductivity and thermoelectric figure of merit (zT) of the CZFCTS thin films have been evaluated, yielding an estimated maximum zT range of 0.18-0.69 at 550 K. The simple processing route and improved thermoelectric performance make CZFCTS thin films extremely promising for thermoelectric energy generation.

Effect of Zn substitution on magnetic properties and magnetic entropy change in La0.7Ba0.25Nd0.05Mn1-xZnxO3 (x = 0.03 and 0.05) synthesized by using sol-gel method

This investigation explored the structural, magnetic, and magnetic entropy change characteristics of La0.7Ba0.25Nd0.05Mn1-xZnxO3 (x = 0.03 and 0.05) synthesized through the sol-gel method. The structural analysis revealed the crystallization of both samples in a Rhombohedral structure with the R-3c space group. The examination of magnetic properties indicated a suppression in magnetic behavior, with the ferromagnetic-paramagnetic transition temperature (TC) decreasing from 285 K to approximately 260 K with an increase in Zn content (x) from 0.03 to 0.05, respectively. The maximum value of magnetic entropy change (−ΔSM) under an applied magnetic field of 50 kOe was determined to be 3.96 J/kg·K for x = 0.03 and 2.27 J/kg·K for x = 0.05. Analysis of Arrot plots and the universal curve of magnetic entropy change confirmed that the ferromagnetic-paramagnetic phase transition observed in both samples exhibits a second-order phase transition (SOPT) transformation.

Thermoelectric Properties of Zn-Doped YbMg1.85-xZnxBi1.98.

Bi-based YbMg2Bi1.98 Zintl compounds represent promising thermoelectric materials. Precise composition and appropriate doping are of great importance for this complex semiconductor. Here, the influence of Zn substitution for Mg on the microstructure and thermoelectric properties of p-type YbMg1.85-xZnxBi1.98 (x = 0, 0.05, 0.08, 0.13, 0.23) was investigated. Polycrystalline samples were prepared using induction melting and densified with spark plasma sintering. X-ray diffraction confirmed that the major phase of the samples possesses the trigonal CaAl2Si2-type crystal structure, and SEM/EDS indicated the presence of minor secondary phases. The electrical conductivity increases and the lattice thermal conductivity decreases with more Zn doping in YbMg1.85-xZnxBi1.98, whereas the Seebeck coefficient has a large reduction. The band gap decreases with increasing Zn concentration and leads to bipolar conduction, resulting in an increase in the thermal conductivity at higher temperatures. Figure of merit ZT values of 0.51 and 0.49 were found for the samples with x = 0 and 0.05 at 773 K, respectively. The maximum amount of Zn doping is suggested to be less than x = 0.1.

The role of Sn and Zn substitutions on the magnetic properties of nanosized Y-type hexaferrite prepared by sol-gel auto-combustion method

The current paper has focused on the improvement of the magnetic performance of the Sn, Zn-doped Y-type hexaferrite nanoparticles via the sol–gel auto-combustion method. The partial replacement of nonmagnetic Zn2+ and Sn4+ cations for the magnetic Fe3+ cation was studied. At the low Zn-Sn concentration, the Sn4+ cations had a preference for octahedral locations (12k, 2a, 4f2) and the Zn2+ cations had a strong tendency to move to the tetrahedral spaces (4f1), respectively. Based on this data, the single-phase hexaferrites with the chemical formula of Sr2Co1.7Mg0.3Fe(12-x)Snx/2Znx/2O22 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0) were successfully synthesized via the sol–gel auto-combustion method. The x-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Thermal Gravimetric Analysis (TGA), Differential Thermal Analysis (DTA), Field Emission Scanning Electron Microscopy (FESEM) and Vibrating Sample Magnetometer (VSM) were carried out to investigate the obtained ferrite performance. The results revealed the formation of the single-phase platelet-like Y-type hexagonal ferrites after calcinations at 1000 °C with a thickness of 30–70 nm and a particle size of 90–210 nm. The obtained nanosized ferrites had the magnetic coercivity (Hc) and the saturation magnetization (Ms) in the range of 2100–637 Oe and 38–48 emu g−1, respectively. The addition of Sn, Zn dopants enhanced the saturation magnetization and reduced the magnetic coercivity, which can make this ferrite a candidate for some applications.

Contribution of Li substitution for Zn to green light emission of ZnO ceramic thin films

In this paper, lithium-doped ZnO films were precipitated on n-type Si (100) substrates by the sol-gel method. The crystal structure, surface morphology, and luminescence properties of the lithium-doped ZnO films were investigated. The results of the X-ray diffractometer (XRD) measurements show that the ZnO thin films with different lithium doping concentrations all have an obvious preferred orientation. According to the fitting result of photoluminescence (PL) spectra, we identify the existence of Li substitution for Zn acceptor defects and that the green emission peaks are caused by the dual effects of single ionized oxygen vacancy (VO•) to the valence band top and VO• to Li substitution for Zn acceptor transitions. From the PL spectra, no matter the number of spin-coated layers, there is a corresponding lithium doping ratio, which can make the Li substitution for Zn (LiZn) acceptor defects concentration reach saturation. Under the same spin-coated layer, the visible luminescence intensity is significantly enhanced with an increase in lithium doping concentration. When the doping concentration reaches a certain value, the luminescence intensity reaches its maximum. Due to concentration quenching, a higher lithium doping ratio will result in a decrease in luminescence intensity.

Visible Light Photocatalytic Degradation of Environmental Pollutants Using Zn-Doped NiO Nanoparticles

The study aims to contribute valuable insights into the potential applications of the photocatalyst, particularly in the realms of sustainable energy and environmental remediation. Here, Zn-doped NiO nanoparticles with different mole percentages of zinc ingredients are produced and analyzed. Synthesized Zn-doped NiO nanoparticles were evaluated structurally, optically, morphologically, elementally, and photocatalytically. According to X-ray diffraction analysis, cubic NiO and hexagonal Zn-doped cubic NiO nanoparticles were formed, and Fourier transform infrared spectroscopy revealed metal dopants and metal-oxygen stretching, as well as Zn substitution and stabilization. A UV analysis revealed that zinc dopants reduced visible light absorption and bandgap. A decrease in bandgap indicates the importance of zinc incorporation and its interface with NiO. Electron scanning microscopy and transmission electron microscopy confirmed that the nanoparticles exhibited quasi-spherical morphologies and contained Ni, Zn, and O elements. Photocatalytic activity of the synthesized Zn-doped NiO nanoparticles increased with increasing Zn content, achieving a maximum at 8% Zn doping into NiO lattices of 92%. Through XPS analysis, the valencies of Zn, Ni, and O elements are demonstrated, as well as electron movements and bonding between the atoms. The zinc dopants on the metal oxide surface led to charge separation and radical reactions, resulting in enhanced degradation of phorate, salbutamol, and rhoda mine B activities. Hence, Zn-doped NiO nanoparticles are proposed as effective photocatalysts for environmental remediation. The findings are expected to have implications for advancing the field of photocatalysis and addressing challenges related to pollution and energy sustainability.

Photovoltaic properties of novel quaternary chalcogenides based on high-throughput screening and first-principles calculations

<sec>In recent decades, the demand for clean energy has promoted extensive research on solar cells as a key renewable energy source. Among the various emerging absorber layer materials, Kesterite-type semiconductors have aroused significant interest. Especially, Kesterite Cu<sub>2</sub>ZnSnS<sub>4 </sub>(CZTS) stands out as a promising candidate for low-cost thin-film solar cells due to its direct bandgap, high optical absorption coefficient, suitable bandgap (1.39–1.52 eV), and abundance of constituent elements. However, the power conversion efficiency (PCE) of CZTS-based solar cells currently lags behind that of Cu(In,Ga)Se<sub>2</sub> (CIGS) cells, mainly due to insufficient open-circuit voltage caused by a large number of disordered cations and defect clusters, resulting in non-radiative recombination and band-tail states.</sec><sec>To address these challenges, partial or complete cation substitution has become a viable strategy for altering the harmful defects in CZTS. This study proposes a heterovalent substitution of Zn in CZTS and explores the potential of novel quaternary chalcogenide compound <i>A</i><sub>2</sub><i>M</i><sub>2</sub><i>M'Q</i><sub>4</sub> (<i>A</i> = Na, K, Rb, Cs, In, Tl; <i>M</i> = Cu, Ag, Au; <i>M'</i> = Ti, Zr, Hf, Ge, Sn; <i>Q</i> = S, Se, Te) as absorbers for solar cells. By substituting elements in five prototype structures, a comprehensive material database comprising 1350 <i>A</i><sub>2</sub><i>M</i><sub>2</sub><i>M'Q</i><sub>4</sub> compounds is established.</sec><sec>High-throughput screening and first-principles calculations are used to evaluate the thermodynamic stabilities, band gaps, spectroscopic limited maximum efficiencies (SLMEs), and phonon dispersions of these compounds. Our research results indicate that 543 compounds exhibit thermodynamic stability (<i>E</i><sub>hull</sub> < 0.01 eV/atom), 202 compounds possess suitable band gaps (1.0–1.5 eV), and 10 compounds meet all the criteria for thermodynamic and dynamic stability, suitable band gaps, and high optical absorption performance (10<sup>4</sup>–10<sup>6</sup> cm<sup>–1</sup>), with theoretical SLME values exceeding 30%.</sec><sec>Notably, <i>Ibam</i>-Rb<sub>2</sub>Ag<sub>2</sub>GeTe<sub>4</sub> exhibits the highest SLME (31.8%) in these candidates, featuring a band gap of 1.27 eV and a small carrier effective mass (< <i>m</i><sub>0</sub>). The electronic structures and optical properties of these compounds are comparable to those of CZTS, which makes them suitable for highly efficient single-junction thin-film solar cells.</sec><sec>All the data presented in this work can be found at <ext-link ext-link-type="uri" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://www.doi.org/10.57760/sciencedb.j00213.00006">https://www.doi.org/10.57760/sciencedb.j00213.00006</ext-link>.</sec>

Microstructure and thermoelectric properties of pristine and Al-doped ZnO ceramics fabricated by cost-effective and eco-friendly wet chemistry methods

ZnO has potential as a thermoelectric material for high-temperature applications, but its performance is limited by the strong interconnection between electrical and thermal transportation. In this study we proved that ZnO bulk samples produced from cost-effective and environmentally friendly nitrates via ultrasonic spray pyrolysis and modified chemical precipitation methods followed by spark plasma sintering, demonstrate significantly higher thermoelectric performance than those fabricated from commercially available ZnO powder. To further explore the potential of the developed chemical precipitation technique, we synthesized a series of Al-doped samples with a nominal composition of Zn1–xAlxO (x = 0.02, 0.04, 0.06). The substitutuion of Al into the ZnO structure led to two significant effects: (i) a partial substitution of Zn with Al boosts the power factor; (ii) the formation of the ZnAl2O4 spinel phase acting as scattering center for phonons in addition to the mass and strain fluctuations induced by the partial Zn-Al substitution, both leading to the thermal conductivity reduction. As a result, Al doping led to a threefold enhancement of the thermoelectric performance with zT value of ∼0.12 achieved at 1100 K for the Zn0.94Al0.06O sample.