Perovskite Samples Research Articles

Influence of La3+ doping on structural and optical properties of SrCeO3 perovskite

The SrCe1-xLaxO3 (x = 0.0, 0.02, 0.4, 0.6, and 0.10) perovskite materials have been successfully synthesized by auto-combustion method and calcined at 1100°C. The XRD patterns reveal a highly crystalline orthorhombic crystal structure with a Pnma space group in all samples. The TEM micrograph shows a spherical morphology of the 10 mol% La3+ doped SrCeO3 perovskite sample alongwith the SAED pattern confirming its highly crystalline nature. The incorporation of La3+ ion in the SrCeO3 perovskite has been confirmed by the Raman and Fourier transform infrared (FTIR) measurements. The UV–vis absorption spectra at room temperature show various bands, with a strong absorption band observed below 400 nm. The optical band gap of the undoped and La3+ doped samples have been calculated and it is smaller for the La3+ doped perovskite samples than that of the undoped perovskite sample. Therefore, the La3+ doped SrCeO3 perovskite may be applicable for optoelectronic applications.

Synthesis and Thermoluminescence Characterization of Ba₆Y₂W₃O₁₈ Perovskite Nanosensors for Dosimetry

Through the citrate-assisted sol-gel method, barium gadolinium tungstate (Ba6Y2W3O18) perovskite samples were synthesized, and their luminescence properties were investigated. Through X-ray diffraction (XRD) the crystal structure of the prepared samples was examined. The tunnelling electron microscopy (TEM) analysis has confirmed the agglomeration of the nanoparticles into rods with an average diameter and length of 71 and 214 nm, respectively. The thermoluminescence (TL) properties were investigated by; first, estimating the number of composing TL components using both experimental and computational methods; second, studying the dose-response of the glow curves in response to the irradiated beta dose. The third step in the study of the TL properties was to assess the reusability of the prepared samples in TL dosimetry and the fourth step was to estimate the minimum detectable dose of the phosphor samples. The Computerized Glow Curve Deconvolution (CGCD) method was then used to extract the kinetic parameters of the composing TL peaks.

Structural Stability of Mixed‐Halide Perovskite Nanocrystals in Energy Storage: The Role of Iodine Expulsion

AbstractIn the pursuit of efficient optoelectronics devices, hybrid lead halide perovskite quantum dots (PQDs) have emerged as highly promising semiconductor materials due to their intriguing properties. While these materials have been used in many applications, the fundamental understanding of their behavior remains relatively unexplored, especially for the mixed halide perovskite samples. To facilitate the advancement of PQD technologies for commercial applications, it is essential to gain insights into the role of ion migration. This study delves into the fundamental aspects of ion migration in halide perovskite nanocrystals. Porous electrodes for supercapacitor application were fabricated using CsPbBr3–xIx (x=0,1,2) nanocrystals prepared via the ligand‐assisted re‐precipitation (LARP) method. Three‐electrode electrochemical measurements and several other characterizations were conducted under dark conditions to evaluate device performance and elucidate the impact of mixed halides on device kinetics and stability. X‐ray photoelectron spectroscopy before and after the electrochemical measurement reveals intriguing findings. Notably, the analysis uncovered the phase segregation in the metal halide perovskite nanocrystals with particular emphasis on CsPbBr2I due to its distinctive mixed‐halide behavior. The specific capacitance increases with the increasing cycles. Interestingly, as the iodide content increases, there is no selective halide expulsion as the structure collapses rapidly.

Kinetics of N2O decomposition over bulk and supported LaCoO3 perovskites

For the first time, kinetic data on the decomposition of N2O over mixed oxide LaCoO3 with a perovskite structure have been obtained. Bulk LaCoO3 synthesized using microwave activation exhibited an increased intrinsic reaction rate with a 30 kJ mol–1 lower activation energy. Perovskite samples supported on ZrO2-La demonstrated lower intrinsic reaction rates due to the lower content of the LaCoO3 phase, but the activation energies were also lower by 50–80 kJ mol–1.

Study the influence of Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite on optical, magnetic and antibacterial properties

Recently, we produced low cost SrFeO3-δ perovskite with antibacterial properties. In this study to improve the antibacterial properties of SrFeO3-δ perovskite, we doped it with silver. Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples were prepared by sol-gel method. Structural properties of these samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution TEM (HR-TEM), EDS elemental mapping and Fourier transform infrared spectrometer (FT-IR). These techniques confirmed the presence of small amount of cubic Ag spherical nanoparticles on the surface of the cubic Sr1-xAgxFeO3-δ perovskite structure. Further, X-ray photoelectron spectroscopy (XPS) for these samples revealed the presence of Ag1+ ions, oxygen vacancies and mixed valence states of Fe ions on the surface of the samples. The energy band gap of these samples was estimated using Kubelka–Munk equation and its value increased with increasing Ag up to x = 0.10. Additionally, Magnetic hysteresis (M − H) loops revealed that these samples displayed antiferromagnetic behavior with a small amount of ferromagnetic order. Finally, the antibacterial properties of these samples revealed that the antimicrobial activities were improved with increasing Ag (x = 0.10). Our results showed that Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples are a promising antimicrobial agent.Graphical

Efficiently high energy storage density in Ba2+ ion modified K0·5Na0·5NbO3 (KNN) ferroelectric ceramics for super capacitors

In the present work, Perovskites BaxK0.5-xNa0.5NbO3 (x = 0.00, 0.05, 0.10, 0.15, 0.20) were synthesized via solid-state synthesis technique. XRD analysis confirmed the successful phase formation of the synthesized perovskites. Further, Rietveld refinement revealed the presence of coexisting orthorhombic and tetragonal phases. High-resolution transmission electron microscopy (HRTEM) was employed to explore the lattice fringes and SAED patterns at nano scale level of prepared samples. The morphology was investigated using a field emission scanning electron microscope (FESEM). Dielectric measurements indicated that both the dielectric constant (ε′) and loss tangent (tan δ) exhibited significant dispersion at low frequencies and high temperatures. Notably, the Ba-doped perovskite samples demonstrated enhanced dielectric properties compared to the undoped KNN sample, with Ba0·1K0·4Na0·5NbO3 (x = 0.10) showing optimal dielectric performance, characterized by a dielectric constant (ɛ՛⁓4000) and a tanẟ ⁓7.23 at 100 Hz frequency and room temperature.AC conductivity is observed to increase with increasing both frequency and temperature. DC conductivity exhibited positive temperature coefficient indicating the semiconductor-like behavior of the prepared samples. The ferroelectric behavior was confirmed through P-E hysteresis curves and Ba0·1K0·4Na0·5NbO3 sample revealed the highest energy storage density among all prepared samples making it a suitable candidate for energy storage applications.

Yttrium Metal–Organic Framework Nanocrystals for Two‐Step Deposited Perovskite Photovoltaics with Enhanced UV‐light Durability

AbstractMetal–organic frameworks (MOFs), renowned for their porous and tunable functionalities, hold significant potential for enhancing perovskite photovoltaic. However, the influence of MOF, particularly those with balanced cations in the pores, on the conversion of bottom‐layer PbI2 and the distribution of MOFs within perovskite remains underexplored. Herein, a newly synthesized Yttrium (Y)‐MOF material is introduced, featuring dimethylamine (DMA) as balanced cations within its pores and strong absorption in UV regime, to modify perovskite films. Y‐MOF, rich in oxygen and nitrogen sites, and featuring DMA within its pores, can passivate uncoordinated Pb2+ in perovskite. Scanning electron microscopy (SEM) and grazing incidence wide‐angle X‐ray scattering (GIWAXS) analysis of the top and bottom surfaces for pristine and Y‐MOF‐assisted perovskite samples reveal that the presence of PbI2 in the Y‐MOF‐assisted perovskite films is negligible. In situ UV–vis analyses demonstrate that the incorporation of Y‐MOF decelerates the crystallization kinetics of perovskite, facilitating the development of larger perovskite grains. Moreover, GIWAXS experiments conducted at different angles reveal the predominant bottom distribution of Y‐MOF within the perovskite, which effectively mitigates the impact of ultraviolet light on the perovskite. Consequently, the Y‐MOF‐assisted devices to achieve an efficiency of 24.05% with improved stability especially the UV‐light stability.

Effect of “Mn” substitution at B-site, on the crystal structure and energy storage performance of the La0.75Sr0.25CoO3 perovskite

This study explores the potential of redox-active electrode materials to address challenges in high-energy–density batteries and supercapacitor devices, including limited cyclic stability, slow charge storage kinetics, and low electrical conductivity. The investigation focuses on perovskite oxide-based electrodes, known for their compositional flexibility and structural stability, as a promising solution. Lanthanum-based perovskites, synthesized via the sol–gel combustion method, underwent comprehensive analysis, varying manganese (Mn) content from 0.25 to 0.75. Through X-ray diffraction, Rietveld analysis, scanning and transmission electron microscopy, energy dispersive X-ray analysis, and galvanometric potentiostat techniques, the effects of Mn-substitution at the B-site on structural, morphological, electron densities, and electrochemical behavior were thoroughly examined. La0.75Sr0.25Co0.5Mn0.5O3 (LCM-2) emerged as a stable variant with low internal strains, exhibiting the highest specific capacity (713C/g at a 2 mV/s scan rate) among all perovskite samples. Notably, LCM-2 perovskite displayed low electron density, which is attributed to oxygen deficiency, indicating its potential for application in highly energy-dense electrochemical energy storage devices. This research contributes valuable insights for advancing the development and commercialization of efficient energy storage technologies.

Exploration of Hierarchically Porous Perovskite Ba0.5Sr0.5FeO3 Catalyst Through Experimental and Computational Investigations for Sustainable Synthesis of Acrolein

Ba0.5Sr0.5FeO3, SrMn0.5Fe0.5O3, and BaMn0.5Fe0.5O3 perovskite catalysts were synthesized via the hydrothermal method. The developing perovskite catalysts with dual bed, redox and acid/base sites, for direct oxidation reactions is one of the recent/important research ideas. Therefore, this study deals with the impact of substituting A and/ or B sites on the catalytic oxidative reactivity of mixed oxides perovskite catalysts. Then, their reactivity was tested in a single reactor oxidative coupling of methanol/ethanol mixture for sustainable acrolein production. The Ba0.5Sr0.5FeO3 perovskite sample has the highest catalytic performance at low temperatures (300○C) with 78% acrolein selectivity, followed by SrMn0.5Fe0.5O3 (65%), then BaMn0.5Fe0.5O3 (58%). The enhanced catalytic reactivity of Ba0.5Sr0.5FeO3 is associated with its effective acidic property and the ability to form O-vacancies easily, so, the strong proclivity for C–C coupling formation.

Delaying crystallization and anchoring the grain boundaries defects via π-π stacked molecules for efficient and stable wide-bandgap perovskite solar cells

Owing to the easy migration of halogen ions in wide-bandgap perovskite, it will lead to the formation of a large number of uncoordinated Pb2+ to form deep-level defects, which seriously affects the power conversion efficiency (PCE) and stability of wide-bandgap perovskite solar cells (PSCs). The introduction of additives has been recognized as an effective method to improve these defects, especially Lewis acid-base additives. Herein, Lewis base molecule dibenzofuran (DBF) with π-conjugated system, which can form π-π stacked dimer, is used as a perovskite additive. The detailed crystallization process of perovskite main precursor triggered by DBF is measured by using laser scanning confocal microscopy. It is demonstrated that the addition of DBF in perovskite samples resulted in a deceleration of the crystallization process, which is due to the formation of Lewis acid-base complexes between DBF π-π stacked dimer and perovskite, which can obtain perovskite films with reduced defect density. As a result, the champion PCE of the wide-bandgap (1.68 eV) perovskite device reaches 20.18 %, significantly higher than the control device (17.79 %). Additionally, the device with no encapsulation demonstrates better stability, as it maintains over 90 % of the initial PCE under an air environment with 30–40 % relative humidity (RH) and 25 °C for 1200 h.

Exploring Ca and Sr stannate perovskites as adsorbents for Congo Red removal

Organic azo-dyes, including Congo Red, present a significant environmental concern due to their widespread industrial usage and resistance to biodegradation, leading to severe contamination of effluents. This study explores the efficacy of two basic perovskites (MSnO3, where M = Ca and Sr) in removing Congo Red by adsorption, offering a potential solution for wastewater treatment. The synthesis of the adsorbents was performed by a coprecipitation technique, an effective and no-waste producing method. By adjusting reaction conditions, the physical-chemical characteristics of the perovskites, including crystallinity, morphological features, surface area and porosity, were controlled. Adsorption studies conducted across a range of Congo Red concentrations (10–100 mg L− 1) at pH 10 revealed MSnO3 to possess exceptional adsorption capacity exceeding 100 mg per gram. The results indicate irreversible adsorption and potential adsorbent regeneration by thermal treatment. Slow kinetics also suggest strong binding forces aligned with the fundamentals of pseudo-second-order adsorption kinetic model. Regarding the impact of the synthesis parameters, while the precipitation conditions may not significantly influence adsorption performance, perovskite samples synthesized at higher temperatures are considered more suitable for this application due to their enhanced stability and regenerative capabilities for repeated use. Estimated correlations between sample parameters and adsorption efficiency provide a valuable insight for the practical application of oxide perovskites in addressing dye contamination issues.

Structural analysis and Rietveld refinement of YCr1-xFexO3 (x=0, 0.5) perovskite samples calcined at two different temperatures

In the present work, we have synthesized polycrystalline YCr1-xFexO3 (x = 0, 0.5) perovskite samples using the traditional high-temperature solid-state reaction route (HT-SSRR) at two different temperatures for calcination (1000 °C as well as 1150 °C). The main objective of our investigation is to observe how these calcination temperatures impact the structural properties of the polycrystalline YCr1-xFexO3 (x = 0, 0.5) perovskite samples and reveal the comparative difference based on structural analysis and Rietveld refinement. The powder XRD analysis confirmed the presence of secondary phases, including Y2O3, Cr2O3, and Fe2O3, in the synthesized samples at both calcination temperatures. Notably, a higher calcination temperature (1150 °C) led to a reduction in the secondary phases and an increase in the crystalline size as determined by the Debye-Scherrer method (DSM). The FullProf software suite was used for performing a Rietveld refinement of the powder X-ray diffraction (PXRD) data. These findings suggest the crucial role of calcination temperature in tailoring the phase purity and crystallinity of YCr1-xFexO3 (x = 0, 0.5) perovskites.

Fabrication and performance investigation of high entropy perovskite (Sr0.2Ba0.2Bi0.2La0.2Pr0.2)FeO3 IT-SOFC cathode material

The high-entropy oxide (HEO) concept expands the design space of solid oxide fuel cell (SOFC) cathode materials. There is great potential for the development of HEO cathode materials that has not been fully explored, and the relationship between their chemical composition, grain size, and electrochemical performance is not yet fully understood. This experimental design involved the preparation of single-phase perovskite (Sr0.2Ba0.2Bi0.2La0.2Pr0.2)FeO3 HEO SOFC cathode materials, and we systematically studied the effects of synthesis temperature and microstructure on their electrochemical performance. The results show that as the synthesis temperature increases, structural transformations from multiphase to single-phase perovskite HEO can be observed. It exhibits excellent conductivity and electrochemical performance (the minimum polarization resistance reaches 0.033 Ω∙cm2, and the maximum power density is 664 mW∙cm−2). The single-phase perovskite HEO sample exhibits higher electrochemical performances compared to those of multiphase perovskite. Furthermore, it exhibits outstanding ability to suppress Sr segregation, chemical compatibility with Ce0.8Sm0.2O1.9(SDC), and CO2 tolerance performance. The Distribution of relaxation time(DRT) analysis shows that as the synthesis temperature (1000–1150 ℃) increase, HEO single-phase formed and the oxygen atom reduction ability of the SBBLP samples was improved; and the adsorption of gas oxygen on the electrode surface is limited with porosity decreases. The work shows it is interesting and valuable to optimize the performance of SOFC cathode materials using a high entropy design.

Enhancement of SrTiO3 photocatalytic efficiency by Al doping: Answers from the structure, morphology and electronic properties contributions

Our study focuses on disclosing the mechanisms standing behind the improved photocatalytic performance of SrTiO3, where Al modification of the perovskite structure boosts the photocatalytic O2 evolution activity of the Al:SrTiO3 system. By adapting the synthesis method that produces well-crystallized materials with low defect density and employing surface modification techniques, we aim to enhance the photocatalytic efficiency of SrTiO3via Al2O3 nanoceramic oxide doping at concentrations ranging from 0 to 10% and further examining of the relationship between doping process and the changes in the electronic and crystalline structure of SrTiO3. The prepared Al-based SrTiO3 perovskite samples (Al3%:SrTiO3, Al7%:SrTiO3, Al10%:SrTiO3) were thoroughly characterized to understand their structural, electronic, and morphological properties. Complementary X-ray techniques were employed to assess the stoichiometry (X-ray photoelectron spectroscopy - XPS), local environment, and chemical state (X-ray absorption spectroscopy - XAS in both total electron yield (TEY) and fluorescence yield (TFY). The comprehensive characterization enables us to understand the changes in the electronic properties and morphological features of the modified samples elucidating the surface formation mechanism while providing insights into the structural modifications induced by Al doping in the SrTiO3 perovskite lattice. Our findings give new perspectives for the development of Al-modified SrTiO3 perovskite materials with enhanced photocatalytic performance providing rich insights into the optimization of photocatalytic processes for applications in environmental remediation and sustainable energy production.

Joint processing of perovskite and ilmenite concentrates. Part 1. Chemical-mineralogical (material) characteristics of perovskite and ilmenite concentrates

Russia has an impressive titanium mineral resource while the contribution into the global production of titanium concentrates is quite insignificant. The current annual demand of Russian enterprises for titanium raw materials is 40 times higher than its production. To improve and launch the processing of domestic titanium raw materials characterized by low quality and complex polymineral composition, new process solutions are required. These solutions should aim at the full extraction of TiO2 and related valuable components from the ore deposits whose development is planned or already started (for example, Afrikanda – perovskite-titanomagnetite deposit located on the Kola Peninsula). This report presents the results of studying the chemical and mineral compositions of perovskite and ilmenite concentrates with the purpose to assess the possibility of their joint processing using carbothermic reduction melting. Emission spectrometry, X-ray diffraction, electron microscopy, and X-ray spectral microanalysis were applied in these studies. It was found that the basis of the ilmenite gravity concentrate sample is modified ilmenite represented by leucoxenization products – pseudorutile and rutile, with their total content in the concentrate to be about 80 wt. %. Composition of other minerals (alumochromite, chromite, magnetite) includes titanium in the form of impurities – 2 – 3 wt. %. In the perovskite flotation concentrate sample titanium is contained in perovskite and titanite making up the bulk of the ore minerals of the concentrate. As for rare and rare-earth elements contained in the ilmenite sample – monazite having up to 33 wt. % Ce, and zircon were found. Perovskite sample contains rare-earth elements (REE concentration in wt. %) in loparite-(Ce) (22.8), aluminocerite-(Ce) (46.2), anсylite-(Ce) (51.3), torite (22.3), as well as in the main mineral – perovskite (2.8). With the exception of perovskite and loparite-(Ce), other REE-containing minerals are rare, and their share in total does not exceed 1 wt. %

Experimental investigation of structural, morphological, and optical characteristics of SrTiO3 nanoparticles using a shock tube for photocatalytic applications

Abstract We investigated the role of dynamic shock waves in perovskite SrTiO3 (STO) material. XRD, FE-SEM, EDAX, FTIR, UV-DRS, XPS, and Raman spectroscopy were all used to examine the title material. When perovskite sample was loaded with shocks, its diffraction pattern did not show any crystal structure changes. The FE-SEM results suggest that the grain size increased linearly with the number of shocks. We used energy-dispersive X-ray spectroscopy to perform elemental analysis; results confirmed that SrTiO3 NPs were indeed present. Although the impulse of the shock wave changed the optical characteristics, it did not affect the molecular structure. To find the optical band gap energies of untreated and shocked NPs, Tauc plot relationships were used. The band-gap energies got smaller as the shock pulse became more substantial. The impact of shock waves caused oxygen vacancies and surface defects, lowering band gap energy. The test for photocatalytic testing showed that SrTiO3 NPs that are loaded with shock waves worked much better when they were exposed to visible light. The characteristics, including stress, strain, and bond length, were found to significantly influence photocatalytic applications. In addition, attempts were made to provide a viewpoint for future study. Overall, the objective of this research was to provide valuable insights for experts engaged in the field of SrTiO3.

Microstructure evolution, dielectric response, and conduction mechanism of La1–xYxFeO3, (0 < x < 0.3) annealed perovskites synthesized via a sol–gel combustion technique

The structural and dielectric characteristics of nano-crystalline La1−xYxFeO3, (0 < x < 0.3) perovskite samples synthesized through the citrate auto-combustion route were investigated. The findings of X-ray diffraction (XRD) analysis revealed that the synthesized perovskites exhibited a polycrystalline orthorhombic structure with a space group Pnma. Furthermore, the tolerance factor was indicative of the phase stability of the orthoferrite series. Based on the refined XRD data, the size of the crystallites was estimated to be between 11.9 and 18.5 nm using size-strain plots (SSP). To gain more insight into the crystal structure, high-resolution transmission electron microscopy (HRTEM) was employed. The estimated size based on HRTEM calculations agreed with the XRD findings. The influence of annealing temperature on the frequency dependence of the dielectric response was thoroughly investigated for nano-crystalline La1−xYxFeO3 perovskites. The investigation took place at room temperature as well as different annealing temperatures, with a comprehensive frequency range of 50 Hz to ~ 2 MHz. The incorporation of Y3+ ions into LaFeO3 (LFO) has resulted in a significant enhancement of the dielectric constant values. This improvement is attributed to the successful integration of Y3+ ions, which have effectively modified the electrical properties of LFO. Furthermore, the annealing has been shown to enhance both the values of the dielectric constant, ε1(ω) and ε2(ω), which are critical parameters for electronic devices. Based on a power law response, the AC conductivity displays an increase with dopant concentration and frequency. Additionally, it has been noted that the activation energy value for LFOY30 is slightly reduced by 0.01 eV in comparison to pure LFO. The AC conductivity of LFOY30 was observed to increase with thermal annealing over the temperature range of 333 K to 463 K. This result confirms the occurrence of thermally activated conduction in the material. Based on this finding, LFOY30 is deemed appropriate for use in applications that require effective heat dissipation. The frequency exponent, s, decreases with increasing temperature from 0.87 to 0.56 for LFO and from 0.488 to 0.42 for LFOY30, respectively, which is associated with the correlated barrier hopping (CBH) model. The maximum barrier height (WM) was around 0.26 eV. The loss tangent (tanδ) variation was estimated as a function of frequency at different dopant concentrations and temperatures. Doping and annealing have been identified as appropriate measures for enhancing the electrical properties of the La1−xYxFeO3 system, thereby making it a useful material for electronic devices.

Synergistic Zinc(II) and Formate Doping of Perovskites: Thermal Phase Stabilization of α-FAPbI3 and Enhanced Photoluminescence Lifetime of FA0.8MA0.2PbI3 up to 3.7 µs.

Adding zinc (II) cations and formate anions improves the thermal phase stability of α-FAPbI3 materials, and the spin-coated thin films of such doped FAPbI3 (produced using MACl) show an increased emission lifetime of up to 3.7 μs on quartz (for FA0.8MA0.2PbI3). This work investigates the effects of zinc and formate on the phase stability and time-resolved photoluminescence of FAPbI3 perovskites for solar cell applications. Perovskite samples with varying concentrations of zinc and formate were made by incorporating different amounts of zinc formate and zinc iodide and were characterized with XRD. Doping levels of 1.7% Zn(II) and 1.0% formate (relative to Pb) seem optimal. The thermal phase stability of the doped perovskite powders (FAPbI3) and thin films (FA0.8MA0.2PbI3) was assessed. XRD of the thin films after 6 months shows only the alpha-phase. The time-resolved photoluminescence spectroscopy of the doped spin-coated perovskite samples (FA0.8MA0.2PbI3 produced using MACl) is reported. The results show that synergy between an anionic and a cationic dopant can take place, making the perovskite thermally more phase-stable (not converting to the yellow delta-phase) with a longer charge carrier lifetime. In order to produce good thin films by spin coating, the use of MACl was essential.

First-principles and machine learning investigation on A4BX6 halide perovskites

The A4BX6 molecular halide perovskites have received attention owing to their interesting optoelectronic properties at the molecular scale; however, a comprehensive dataset of their atomic structures and electronic properties and associated data-driven investigation are still unavailable now, which makes it difficult for inverse materials design for semiconductor applications (e.g. wide band gap semiconductor). In this manuscript, we employ data-driven methods to predict band gaps of A4BX6 molecular halide perovskites via machine learning. A large virtual design database including 246 904 A4BX6 perovskite samples is predicted via machine learning, based on the model trained using 2740 first-principles results of A4BX6 molecular halide perovskites. In addition, symbolic regression-based machine learning is employed to identify more physically intuitive descriptors based on the starting first-principles dataset of A4BX6 molecular halide perovskites. In addition, different ranking methods are employed to offer a comprehensive feature importance analysis for the halide perovskite materials. This study highlights the efficacy of machine learning-assisted compositional design of A4BX6 perovskites, and the multi-dimensional database established here is valuable for future experimental validation toward perovskite-based wide band gap semiconductor materials.

Structural, thermal, optical, magnetic and electrical properties of Fe doped Ba0.77Ca0.23TiO3 perovskite

The most known ferroelectric ceramic material is Barium Titanate (BaTiO3), which is frequently used in actuators, capacitors, and memory devices. The ferroelectric properties of Barium Titanate were improved by doping a small amount of other dopants. Choosing a material with high ferroelectric, piezoelectric, dielectric, and magnetic constants, low dielectric loss, and high electrical resistivity is necessary. In order to achieve the purpose, the suggested sample is formed as Ba0.77Ca0.23Ti1-xFexO3, where x is equivalent to 0.0, 0.05, 0.15, and 0.20. We doped iron (Fe), replacing titanium, and the percentage of calcium was fixed. The composition was synthesized by the conventional solid-state reaction (SSR) method. Effects of ferrite contents (x) on the structural, thermal, optical, dielectric, magnetic, and electrical properties were thoroughly investigated. The structural properties and phase identification were studied by powder X-ray diffraction (XRD), confirming the formation of the cubic crystal structure of perovskite samples. While increasing Fe contents (x), the lattice parameter of the samples increases slightly but dramatically decreases for x = 0.20. Differential Scanning Calorimeter (DSC) results that the specific heat capacity is highest at 1100 °C. Fourier-transform infrared spectroscopy (FTIR) analyses confirmed the metal-oxygen corresponding bonds at 370 cm−1 and 530 cm−1 in the perovskite structure. The bandgap (Eg) values decrease from 2.46eV to 1.75eV with Fe added in the sample studied by exploiting ultraviolet–visible spectroscopy (UV–Vis). The magnetization increases with the addition of an applied magnetic field and Fe contents. The dielectric parameters, permeability, impedance, and AC resistivity have been extracted from the measurement of the Impedance Analyzer. As band gap energy decreases, the compositions can be good candidates for memory devices. Low magnetization can make these compositions a good choice for spintronics, memory devices, and catalysis.