Search Results (940)

Oxide perovskites with simultaneously large band gaps and high-static dielectric constants are of considerable interest for advanced microelectronics, dielectric devices, and energy storage applications, yet their discovery remains challenging because electronic insulation, lattice polarizability, and thermodynamic accessibility are strongly coupled and often mutually competitive. Here, we develop a physics-guided multitask learning framework for the joint prediction of the band gap and static dielectric response in chemically constrained single-perovskite oxide ABO₃ compounds. To ensure data fidelity and physical comparability, the learning space is strictly restricted to simple oxide ABO₃ perovskites from the Materials Project, while mixed-fidelity band gaps, heterogeneous dielectric definitions, and chemically inconsistent samples are excluded. The model integrates role-aware A-/B-site descriptors, perovskite-specific geometric and structural features, multitask prediction of Eg, εtotal, εelectronic, and εionic, explicit physical consistency constraints, auxiliary candidate classification, ranking learning, and reliability-aware screening with uncertainty and out-of-distribution control. Under B-site-grouped cross-validation, the framework achieves 97.4% accuracy, Recall of 96.5%, and an F1 score of 96.1%, while maintaining robust transferability on the independent JARVIS validation set. The results show that high-gap/high-k candidates occupy a chemically non-random subspace governed by B-site-centered electronic–lattice coupling, and that physically consistent multitask learning substantially improves both predictive coherence and candidate enrichment. More broadly, this study establishes a data-consistent, physics-constrained, and transferable paradigm for the intelligent discovery of functional oxide dielectrics. Full article

This study presents the results of chemical and morphological analyses of conductive layers, indium tin oxide (ITO) and silver, deposited on lead zirconium titanate (PZT) substrates, in the form of ITO/PZT, Ag/PZT, and PZT buffer samples. The buffer layer was also examined to assess any potential impacts on the interface and was obtained by etching silver-coated PZT discs in an acid sonification bath. The ITO/PZT discs were obtained by DC sputtering. Chemical and morphological analyses were conducted using Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). XRD analysis revealed distinct diffraction peaks corresponding to the composition and crystalline structure of the various discs. This established the presence of the expected face-centered cubic (FCC) structure of silver, the perovskite phase of PZT, and the cubic bixbyite structure of the conductive ITO layer. SEM/EDS illustrated the particle distribution and elemental composition of the samples. Raman spectroscopy further corroborated the presence and identity of the surface layers of the samples. The results demonstrate that ITO/PZT structures have the expected compositions and identified impurities. SEM results give insight into possible effects on piezoelectric effects and integration into opto-electronic devices. Full article

Phase formation characteristics during the thermochemical reduction of metals from natural coltan using aluminum and calcium–aluminum alloy at 1400–1450 °C were investigated to develop methods for extracting niobium and tantalum from rare metal raw materials. The studied coltan sample consists of a columbite–tantalite solid solution with the composition (Mn,Fe)(Nb,Ta)₂O₆, cassiterite Sn_0.9O₂, tapiolite (Ta,Nb)₂(Mn,Fe)O₆, and calcioolivine Ca₂SiO₄. This study established that the choice of reducing agent determines the sequence of oxide phase transformations. During the aluminothermic process, orthorhombic columbite–tantalite is completely reduced, while tetragonal tapiolite persists even at 1400 °C. The use of a calcium–aluminum alloy containing 69.4 wt.% Ca results in a reversal of this trend: tapiolite is reduced at the early stages (800–1250 °C) through an intermediate (Ta,Nb)O₂ phase, whereas the columbite–tantalite solid solution remains up to 1250 °C. Calcium, having a high affinity for oxygen, forms intermediate perovskite-type oxide phases that act as diffusion barriers, limiting the access of the reducing agent to residual mineral inclusions (mainly Nb-Ta minerals of the orthorhombic crystal system). A temperature rise to 1450 °C initiates the redistribution of oxide components: the content of CaNbO₃ decreases, the Ca₂(Nb,Ta)AlO₆ phase disappears, and its components are involved in the formation of Ca(Nb,Ta)_0.25MnO_2.74 and Ca₄Nb₂O₉. Diffusion constraints are reduced, and the residual columbite–tantalite solid solution is reduced, as confirmed by its complete absence in the products at 1450 °C. In the metallic phase, solid solutions of tantalum and niobium, Ta-Nb-Sn intermetallic compounds (Ta,Nb)₃Sn, titanium aluminide, and ferroalloys with an increased (Ta,Nb)/(Fe,Mn) ratio are formed. The phase transformations elucidated during metallothermic reduction of coltan using different reducing agents, together with the formation of metallic and intermetallic phases, establish a scientific foundation for the development of advanced rare metal extraction processes. Full article

Perovskite solar cells (PSCs) have quickly achieved certified energy conversion efficiency reaching a certified record of 27.3% for single-junction cells, while having a low mass, thin-film form factor and high specific power, which are attractive for space energy systems. However, their long-term reliability in extraterrestrial environments is not adequately ensured by terrestrial qualification routes, and standardized space-related test protocols remain insufficiently developed. This review critically summarizes the current understanding of the degradation of PSCs under the influence of key environmental factors in space—ionizing and non-ionizing radiation, thermal vacuum exposure and thermal cycling, and ultraviolet radiation AM0, as well as atmospheric oxygen in low orbits. The central task of the work is to develop and justify the need to create specialized PSCs test protocols for space applications, since existing ground standards do not reflect the multifactorial nature and extreme orbital loads. It has been shown that thermal vacuum accelerates ion migration, interphase reactions, and degassing, while AM0 UV and atomic oxygen introduce additional photochemical and oxidative mechanisms of destruction; at the same time, stressors often act synergistically and are not detected by single-factor tests. Next, the limitations of the current IEC and ISOS are discussed and an approach to their expansion is formulated through the ISOS-T-Space and ISOS-LC-Space protocols, which integrate high vacuum, AM0 lighting, extended temperature ranges and controlled particle irradiation. It is concluded that the development and interlaboratory validation of such space-oriented protocols is a key condition for the correct qualification of PSCs and targeted optimization of materials and interfaces to meet the requirements of space energy. Full article

Pure LaFeO₃@C and LaCoO₃@C and substituted LaFe_1-xCo_xO₃ and LaCo_1-xFe_xO₃ perovskites (x = 0.10; 0.30) were used as catalysts for the liquid-phase oxidation of furfural at 150 °C and 30 bar of O₂ pressure. The perovskites were characterized by XRD, H₂-TPR, N₂ physisorption, TPR-MeOH, and XPS. The carbon in situ incorporation (@C) increases the surface area, favoring oxygen mobility leading to LaFeO₃@C stabilizing the redox pair Fe³⁺/Fe²⁺. In contrast, no evidence of the formation of a LaCoO₃@C perovskite structure through @C incorporation was observed. The gradual substitution of Fe with Co (10 and 30%) in LaFeO₃@C decreases the crystallinity, redox and basic properties, and surface area. For LaCoO₃@C, after the substitution of Co with 10 and 30% of Fe, only metal (La, Fe, Co) oxides as segregated phases were observed. The highest catalytic activity and selectivity to maleic acid of LaFeO₃@C is attributed to the higher surface area, crystalline structure, and surface-reducible Fe³⁺ species, favoring oxygen mobility and promoting their more oxidizing capacity. The lower catalytic activity of LaCoO₃@C, the Co- and Fe-substituted LaFeO₃@C and LaCoO₃@C catalysts, is attributed to the smaller surface area, and the similar selectivity towards maleic acid, 5-hydroxy-2(5H) and furanone indicates that the active site type is not modified in comparison to LaFeO₃@C. Full article

Indium Tin Oxide (ITO) is one of the most widely used ohmic materials for fabricating ohmic layers in thin-film solar cells. ITO thin layers have reached almost the maximum theoretical conductivity and the lowest practical resistivity. Along with indium’s toxic environmental impact and the high cost of materials, these are the reasons why new materials for efficient, cheaper thin-film transparent ohmic layers are being examined. One of those materials is copper-doped zinc oxide (ZnO:Cu). In this paper, we present a new approach to copper-doped zinc oxide fabrication methods, based on the modern authorial Physical Vapor Co-Deposition technique, which involves optimizing Cu concentration to fine-tune crystal structure, optical band gap, and electrical properties, creating n-type TCOs essential for efficient charge transport in next-generation thin films perovskite solar cells. Full article

The recovery of oxygen-affine elements such as tantalum (Ta) using pyrometallurgical routes is difficult because this element cannot easily be enriched in a metal alloy, as is the case with battery recycling for the more noble metals Co, Ni, and Cu. A promising procedure, on the other hand, is to enrich this element in simple oxide compounds formed in a silicate melt. This enrichment in tailored mineral compounds is also known as the “Engineered Artificial Minerals” (EnAM) approach. Currently, the Technological Readiness Level (TRL) of this approach is relatively low and limited to understanding the mechanisms involved in the incorporation of target elements and the search for suitable compounds with a high enrichment factor, favorable morphology, and early crystallization during solidification in order to achieve maximum recovery yield of the selected compound (element). Due to its high ion charge (high field strength) and small ion radius for a heavy element, it is plausible that Ta behaves similarly to the abundant element titanium (Ti), whose chemistry is much better known. Ti minerals such as ulvospinel, perovskite, ilmenite, and pseudobrookite are therefore suitable candidates in the search for a suitable tantalum EnAM. A comparison of the solidification of synthetic silicate melts dominated by iron and calcium with Ti as an additive show that Ta is not incorporated into ulvospinel formed in olivine-containing Fe-rich silicate melts (base composition with 57 wt.% FeO). In contrast, the perovskites formed in silicate melts dominated by calcium-alumosilicate (max. 10 wt.% FeO addition) do incorporate Ta. Crystal size and Ta content increase with increasing iron content (up to a maximum of about 10 wt.%). The results indicate a possible solid solution with the well-known compounds CaTiO₃ and FeTiO₃ and the virtual compounds Ca_0.8TiO₃ and Fe_0.8TiO₃. Full article

We develop Cs_xFA_1−xPbI₃ perovskite photodetectors with varying Cs content in the x = 0.05–0.25 range to identify the most stable cubic-lattice perovskite composition for visible-light photodetection. The perovskite layers were deposited by the spin-coating technique on a nickel oxide p-type contact and then were covered with C₆₀/Ag electron contact to obtain a vertical pin diode structure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements show that x = 0.1–0.2 provides the most stable lattice and pinhole-free perovskite layers. The photocurrents are linear in an extremely wide 1 nW–10 mW excitation power range, providing photoresponsivity of 0.28 A/W at 532 nm (green light), similar to that of Si photodiodes. The testing of the photodetectors using picosecond pulses provided their rise times and fall times. The x = 0.2 composition provided the shortest rise time values of 27.5 ns, leading to a detector modulation bandwidth of 12.7 MHz. This indicates that this perovskite composition is suitable for replacing silicon photodetectors in cost-efficient light detection systems for imaging and light communication applications such as Li-Fi. Full article

The control of oxygen stoichiometry via topochemical reduction offers a powerful route to manipulate the functional properties of complex oxides. Here, we investigate the chemical and structural evolution of epitaxial BiFeO₃ (BFO) thin films under CaH₂ treatment in a sealed tube, using a representative reduction condition of 365 °C for 2 h and a temperature window of 345 to 380 °C to probe the reduction dependent evolution. The inherent sensitivity of BFO’s multiferroic properties to oxygen vacancy formation and cation valence states makes it an ideal platform to probe reduction pathways. The aim of this work is to elucidate the detailed reduction pathway, including phase stability, valence changes in Bi and Fe, and the morphological consequences of oxygen extraction. Using a combination of spectroscopic, diffraction, and microscopic techniques, it was demonstrated that CaH₂ annealing does not yield a homogeneous oxygen-deficient perovskite. Instead, it triggers a decomposition into Bi₂O₃, metallic Bi, and FeO_x secondary phases, accompanied by severe surface roughening. This chemical reconstruction leads to a strong suppression of the ferromagnetic-like response and a redshift in the optical absorption edge. Full article

Sn-based perovskites offer lower lead content but face a major challenge: Sn²⁺ oxidizes readily, which has led most research groups to use gloveboxes and chemical additives during processing. Here, we investigate whether precursor molarity alone can mitigate this oxidation problem in ambient air. MAPb_0.75Sn_0.25I₃ solar cells with mesoporous N–i–P architecture were prepared from 1.0 M and 0.9 M solutions by spin-coating with ethyl acetate antisolvent, under standard lab conditions (28–34 °C, 30–45% RH). The characterization included SEM, XRD, XPS, profilometry, and J–V measurements. The 0.9 M concentration produced thinner films (275 nm vs. 474 nm), better Sn²⁺/Sn⁴⁺ ratios (16.5%/83.5% vs. 77.6%/22.4% by XPS), lower band gaps (1.51–1.52 vs. 1.55–1.56 eV), and larger grains. Device efficiency increased from 1.61 ± 0.68% (1.0 M) to 4.53 ± 0.91% (0.9 M), with the best cell reaching 5.91%—about 85% of our MAPbI₃ control (6.96%). After one month of storage, 0.9 M cells retained 61% efficiency compared to 37% for 1.0 M devices. These findings demonstrate that a simple reduction in precursor molarity can substantially suppress Sn⁴⁺ formation during ambient fabrication, providing a practical route for laboratories without controlled atmospheres. Full article

Lead-free double perovskites possess the capabilities of wide bandgap control, excellent photoelectric performance, and environmental friendliness. They are an ideal alternative system for addressing the heavy metal toxicity of lead-based perovskites and promoting their large-scale application. Precise control of their bandgap is key to the green transformation of optoelectronic devices. Bandgap, as a key parameter determining the photoelectric properties of materials, has limitations in traditional experimental determination and DFT calculation methods, such as being time consuming, labour intensive, costly, and difficult to achieve high-throughput screening. Deep learning provides an efficient solution to this problem, but current research has issues such as a single-model architecture and poor interpretability, which cannot effectively support bandgap regulation. This study utilised 2367 valid datasets of lead-free double perovskites sourced from the Materials Project database and relevant literature. Following preprocessing steps, including MinMaxScaler normalisation and Pearson correlation coefficient screening, the dataset was divided into a ratio of 7:1:2. The bandgap prediction capabilities of four models—MLP, deep ensemble learning, PINN, and Transformer—were systematically compared, with feature importance analysed using the SHAP method. The results show that the MLP model performs the best in medium-scale, structured feature prediction. The R² value of the test set is 0.9311, while the MAE, MSE, and RMSE are 0.1915 eV, 0.0975 eV², and 0.3122 eV, respectively. A total of 98% of the test samples have a prediction error of ≤0.4 eV, highlighting the stability of low bandgap systems. The Transformer is more suitable for large-scale, sequential feature prediction, while the MLP has limited generalisation ability for medium-to-high bandgap systems containing elements such as Si and Mg. The SHAP analysis revealed that the five electronic structure descriptors, such as B_HOMO+ and A_LUMO+, are the key influencing factors of the bandgap. The research results are helpful for the high-precision prediction and mechanism explanation of the bandgap of lead-free double perovskites, providing theoretical support for rational material design, performance optimisation, and bandgap-oriented regulation. They also point out the direction for subsequent model improvement. Full article

Zinc titanate (ZnTiO₃) is a chemically stable and non-toxic oxide perovskite whose photovoltaic potential remains largely unexplored due to its wide indirect bandgap. This study evaluates whether oxygen-vacancy (F-center) engineering can tailor its electronic structure and improve its suitability as a photovoltaic absorber. Density Functional Theory (DFT) calculations using VASP (PAW − GGA/PBE + U) were performed to evaluate structural stability, electronic properties, and electron affinity, while optical absorption was modeled through a combined Tauc–Gaussian approach. Device performance was assessed via SCAPS-1D simulations in an FTO/ZnO/ZnTiO₃/Spiro-OMeTAD architecture. Oxygen vacancies induce bandgap narrowing from ~2.96 eV to ~1.47 eV and generate Ti-3d-dominated donor-like and deep intragap states. The calculated electron affinity is ~3.77 eV. Simulated single-layer devices reach Voc ≈ 1.11 V, Jsc ≈ 8.27 mA·cm⁻², FF ≈ 83%, and a maximum efficiency of ~7.65%, primarily limited by moderate absorption strength and defect-assisted recombination. Multilayer configurations indicate that geometric optimization can significantly enhance projected efficiency, approaching 19.25% under idealized conditions. Although vacancy engineering extends visible-light absorption, the intrinsic indirect band-gap character constrains the ultimate photovoltaic performance of ZnTiO₃. Full article

Perovskite oxide photoanodes are attractive for alkaline water oxidation but are commonly limited by interfacial recombination and sluggish charge transfer. Here we enhance anisotropic SrTiO₃ (STO) photoelectrodes via Al doping by simple yet effective one-step hydrothermal method and identify an optimal composition at 4% Al. In 0.1 M NaOH (pH 13) under simulated AM 1.5G illumination, 4% Al:STO exhibits 2 times enhancement in photocurrent density and 80% increase in electrochemically active surface area compared with the pristine SrTiO₃, as evidenced by the reduced charge-transfer resistance and enlarged light–dark photocurrent gap. together with a markedly reduced interfacial impedance, indicating accelerated charge extraction and transfer. Band-structure analysis shows a positive shift in flat-band potential and slight band-gap narrowing after Al doping, providing more favorable carrier energetics. Steady-state and time-resolved photoluminescence further demonstrate strong PL quenching and a prolonged carrier lifetime for 4% Al:STO. ECSA analysis suggests increased electrochemically accessible surface sites at the optimal doping level. Overall, moderate Al doping synergistically tunes defects, band energetics, and interfacial kinetics to improve STO photoanodes for solar water splitting. Full article

The potential of La_0.2Sr_0.8MnO₃ (LSM28) perovskite oxide for thermochemical energy storage (TCES) is assessed by analyzing its thermochemical performance. The TCES capacity of LSM28 was measured using a non-stoichiometric and van’t Hoff analysis at various reduction temperatures ( T r e d ) and oxygen partial pressures ( P O 2 ). O₂ release and the associated non-stoichiometry (δ) increase with T r e d and decrease with P O 2 , according to the results, reaching a maximum δ of 0.101 at 1473 K and 0.0001 atm. The van’t Hoff research also showed that LSM28’s TCES capacity fluctuates greatly with δ, peaking at 37.1 kJ/kg under ideal circumstances. Full article

Perovskite oxides show excellent catalytic performance for thermochemical CO₂ splitting, with A/B-site cation substitution further enhancing redox activity. While traditional first-principles methods are computationally expensive, machine learning (ML) provides an efficient approach to perovskite optimization. In this paper, machine learning is employed to investigate and predict the performance of perovskite catalysts in CO₂ decomposition reactions. Based on 227 perovskite compositions (A₁A₂)(B₁B₂)O₃ curated from experimental literature, a total of five ML models are used, including Decision Tree, Bagging, Random Forest, Extra Trees, and Gradient Boosting Regression (GBR). The Random Forest model performed best. After hyperparameter optimization, the Random Forest model achieved an R² of 0.910 and an MAE of 41.528 on an independent test set. SHAP analysis indicated that the thermal reduction temperature (T₁) and the B1-site stoichiometric fraction (C_b₁) are the most influential features governing the predicted CO yield. A higher CO yield is predicted when C_b₁ ranges from 0.6 to 0.8, and T₁ exceeds 1300 °C. This behavior can be attributed to the enhanced formation of oxygen vacancies at elevated temperatures and the optimized electronic structure induced by appropriate B-site stoichiometry. Full article