Perovskite Structure Research Articles

Triply Ordered 6H Halide Perovskites: A Family of Triangular Lattice Antiferromagnets.

Three new hexagonal perovskites with Cs3M+M2+RhCl9 (M+ = Na+, Ag+; M2+ = Mn2+, Fe2+) stoichiometry have been synthesized from solution precipitation reactions. These air-stable compounds crystallize as triply cation-ordered variants of the 6H perovskite structure. This structure contains octahedra that share a common face to form M2+RhCl94- dimers that are arranged on a two-dimensional triangular network. M+ cations reside in octahedral holes located between dimer layers and connect M2+RhCl94- dimers through corner-sharing linkages. The cation sites in the corner-sharing layers are fully occupied by Na+/Ag+, except for Cs3AgMnRhCl9, where a small amount of Ag+/Mn2+ antisite disorder is observed. The M2+RhCl94- dimers adopt an ordered configuration that lowers the symmetry from P63/mmc to P63mc. Optical absorption in the near ultraviolet (UV) and visible regions is dominated by Rh d-to-d transitions and metal-to-metal charge transfer transitions. Variable temperature magnetic susceptibility measurements show no sign of long-range magnetic order down to 2 K. Curie-Weiss fits reveal relatively weak antiferromagnetic interactions between M2+ ions, with Weiss constants that range from -2.3 to -5.4 K. The strength of the antiferromagnetic interactions between M2+ ions increases as the covalency of the M2+-Cl bond increases. The ordering of three different cations in the 6H perovskite structure diminishes magnetic coupling between layers, leading to a new family of two-dimensional triangular lattice antiferromagnets.

Novel Self-Powered Sensitive X-Ray Detection Crystal Bi2Mo0.36W1.64O9 with Effective Functional Motif Coupling in a Quasi-2D Perovskite Structure.

The demand for medical imaging with reduced patient dosage and higher resolution is growing, driving the need for advanced X-ray detection technologies. This paper proposes a design paradigm for X-ray detection semiconductors by coupling constituent motifs through crystal structure engineering. The study introduces a strongly anisotropic Aurivillius-type quasi-2D perovskite structure, combining [Bi2O2]2+ groups with stereochemically active lone pair electrons (SCALPEs) and [W/Mo2O7]2- anionic groups, enabling enhanced X-ray Compton scattering and self-powered capabilities through local electric field ordering. This results in the first self-powered Bi-based tungstate Bi2Mo0.36W1.64O9 (BMWO) X-ray detector, achieving a record self-powered sensitivity of 381 µC Gy-1 cm-2. Additionally, the study demonstrates the imaging capability of a Bi-based perovskite X-ray detector operating in self-driven mode. The work highlights BMWO as a promising candidate for stable direct detection imaging and validates the material design strategy that leverages the large anisotropy of quasi-2D structures for sensitive and self-powered detection.

Machine learning recognition of hybrid lead halide perovskites and perovskite-related structures from X-ray diffraction patterns.

Identification of crystal structures is a crucial stage in the exploration of novel functional materials. This procedure is usually time-consuming and can be false-positive or false-negative. This necessitates a significant level of expert proficiency in the field of crystallography and, especially, requires deep experience in perovskite-related structures of hybrid perovskites. Our work is devoted to the machine learning classification of structure types of hybrid lead halides based on available X-ray diffraction data. Here, we proposed a simple approach for quickly identifying the dimensionality of inorganic substructures, types of connections of lead halide polyhedra and structure types using common powder XRD data and a ML-decision tree classification model. The average accuracy of our ML algorithm in predicting the dimensionality of inorganic substructures, the type of connection of lead halide and inorganic substructure topology based on theoretically calculated XRD patterns among 14 most common structure types reached 0.76 ± 0.07, 0.827 ± 0.028 and 0.71 ± 0.05, respectively. To test the transferability of the developed ML model, we expanded our dataset to 30 structure types. The average accuracy of our ML algorithm in predicting the dimensionality of inorganic substructures, the type of connection of lead halide and inorganic substructure topology based on theoretically calculated XRD patterns among 30 structure types reached 0.820 ± 0.022, 0.74 ± 0.05 and 0.633 ± 0.018, respectively. The validation of our decision tree classification ML model on experimental XRD data shows accuracies of 1.0 and 0.82 for dimension and structure type prediction. Thus, our approach can significantly simplify and accelerate the interpretation of highly complicated XRD data for hybrid lead halides.

Electrospun Ba(Ti0.80 Zr0.20)O3-0.5(Ba0.70Ca0.30)TiO3-CoFe2O4 multiferroic hybrid nanofiber for the localized piezocatalytic degradation of organic pollutants

Multiferroic Ba(Ti[Formula: see text]Zr[Formula: see text])O3-0.5(Ba[Formula: see text]Ca[Formula: see text])TiO3 (BCTZ)@CoFe2O4 (CFO) hybrid nanofibers (NFs) were fabricated by a sol–gel electrospinning. The perovskite structure of ferroelectric BCTZ and the spinel structure of ferromagnetic CFO coexist and are homogeneously distributed, and their interface along the perovskite [110] zone axis was directly observed. The indirect magnetoelectric (ME) coupling effect was observed from the magnetization versus temperature (M–T) curves, demonstrating a distinct singularity on the dM/dT curve near the ferroelectric Curie temperature ([Formula: see text][Formula: see text]) of 387 K. The piezocatalytic rate of BCTZ@CFO multiferroic hybrid NF (2.6 × 10[Formula: see text]min[Formula: see text]) is higher than NP (1.9 × 10[Formula: see text]min[Formula: see text]) because the piezoelectricity of the one-dimensional (1D) multiferroic NF is higher than that of NPs, beneficial for the mechanical vibration-induced localized built-in electric fields for piezocatalysis under ultrasound.

Engineering 0.8BiFeO3-0.2BaTiO3 multiferroics with improved dielectric and magnetic properties via samarium doping.

Samarium (Sm) modification is emerging as a powerful strategy to manipulate the electrical response of 0.8BiFeO3-0.2BaTiO3 (BFBT) multiferroic ceramics. In this work, Sm-doped BFBT (BFBT05Sm and BFBT01Sm) are successfully synthesized via the solid-state reaction technique. X-ray diffraction (XRD) analysis coupled with Rietveld refinement confirms the formation of a pure perovskite structure with rhombohedral symmetry (R3c space group) for all compositions, indicating the effective integration of Sm into the BFBT lattice. In particular, scanning electron microscopy (SEM) reveals a remarkable increase in grain size upon Sm doping, reaching 1.098 μm in BFBT01Sm compared to 0.192 μm in the BFBT sample. Further evidence for the R3c space group comes from Raman spectroscopy, which reveals identical vibrational modes in all samples. Most importantly, the Sm substitution significantly reduces the dielectric loss compared to BFBT. A comprehensive analysis of the Mössbauer spectral parameters reveals the influence of Sm doping on the magnetic interactions.

Observation of Large Low-Field Magnetoresistance in Layered (NdNiO3)n:NdO Films at High Temperatures.

Large low-field magnetoresistance (LFMR, <1 T), related to the spin-disorder scattering or spin-polarized tunneling at boundaries of polycrystalline manganates, holds considerable promise for the development of low-power and ultrafast magnetic devices. However, achieving significant LFMRtypically necessitates extremely low temperatures due to diminishing spin polarization as temperature rises. To address this challenge, one strategy involves incorporating Ruddlesden-Popper structures (ABO3)n:AO, which are layered derivatives of perovskite structure capable of potentially inducing heightened magnetic fluctuations at higher temperatures. Here, a remarkable LFMR of up to 1.0×103% is obtained in the layered (NdNiO3)n:NdO films with a high and wide temperature range (190-240 K). This finding underlines that the layered (NdNiO3)n:NdO (n = 1) structure show a complex magnetic structure above TMI of perovskite NdNiO3, where small ferromagnetic domains are embedded in the antiferromagnetic domains, raising the tunneling barriers and magnetic fluctuations at high temperatures. Furthermore, applying a low magnetic field (<0.1 T) near TMI effectively mitigates the disruption of antiferromagnetic order structures at boundaries, then a higher temperature is required to break the inhibition of ferromagnetic to antiferromagnetic phase transition. The results contribute significantly to the advancement of magnetic devices capable of achieving substantial LFMR at room temperature.

Creation of Piezoelectricity in Quadruple Perovskite Oxides by Harnessing Cation Defects and Their Application in Piezo-Photocatalysis.

Quadruple perovskite oxides have received extensive attention in electronics and catalysis, owing to their cation-ordering structure and intriguing physical properties. However, their repertoires still remain limited. In particular, piezoelectricity from quadruple perovskites has been rarely reported due to the frustrated symmetry-breaking transition in A-site-ordered perovskite structures, disabling their piezoelectric applications. Herein, we report a feasible strategy to achieve piezoelectricity in CaCu3Ti4O12 (CCTO) quadruple perovskite via cation defect engineering, specifically through a thermal-driven selective cation exsolution strategy to introduce Cu vacancies. The introduction of Cu point defects in CCTO locally destabilizes the constrained tilted TiO6 octahedra framework, relaxing the octahedral tilting and inducing structural heterogeneity which, in turn, disrupts the high symmetry of the pristine cubic phase. As a result, the defective CCTO with localized asymmetry exhibits intense polarization and a robust piezoelectricity of 7 pC N-1. The created piezoelectricity is further validated by its application as a piezo-photocatalyst, enabling efficient charge separation and transfer with a 2.5-times increment in the lifetime of photoexcitations. This enhancement leads to a 3.86- and 31-fold increase in the production of hydrogen peroxide and reactive oxygen species compared with individual piezocatalysis and photocatalysis, respectively. This study establishes a pathway to engineer piezoelectricity in quadruple perovskites, potentially unlocking a wide range of applications in modern microelectronics beyond the demonstrated piezo-photocatalysis.

PEROVSKITE SOLAR CELLS AND THEIR TYPES

Perovskite photovoltaic compartments have garnered momentous consideration in photovoltaics owing to their easy manufacturing process and high efficiency. The optoelectronic properties of perovskite solar cells (PSCs), made from halide and diverse-halide materials, are exceptional. Perovskite structures exhibit remarkable stability despite a wide band gap and minimal charge transfer. Some advantages of perovskite solar cells are; high efficiency, low cost, rapid manufacturing, flexibility, energy payback time, sustainability, etc. To address these challenges, multidimensional perovskite materials are utilized to achieve long-term stability and good performance. Recent advancements in low-temperature synthesis methods and improved contact and electrode components have resulted in PSCs surpassing an efficiency of 25%. Perovskites' characteristics can also be enhanced by altering their elemental makeup. The light-harvesting perovskite material, the electron-transporting layer (ETL), the transparent conductive oxide (TCO) film, the hole-transporting layer (HTL), and the metal contact material. The most fantastic and popular perovskite material for sunny collecting at the moment is MAPbI3. Compared to the conventional MAPbI3 perovskite, additional perovskite substances, for example, assorted halide-assorted cation, hybrid cation, and hybrid halide, are drawing more interest. This paper mainly discussed metal-based PSCs, non-metal-based PSCs, and polymer-based PSCs. Moreover, there has been a significant focus on the constancy and production concerns that boundary the commercialization and modularization of perovskite solar cubicles.

Chalcogenide perovskites: enticing prospects across a wide range of compositions and optoelectronic properties for stable photodetector devices

Abstract Photodetectors are indispensable components of many modern light sensing and imaging devices, converting photon energy into processable electrical signal through absorption, carrier generation and extraction using semiconducting thin films with appropriate optoelectronic properties. Recently, metal halide perovskites have demonstrated groundbreaking photodetector performance due to their exceptional properties originating from their perovskite structure. However, toxicity and stability remain challenges for their large-scale applications. Inspired by the perovskite structure, intense investigation in search of highly stable, non-toxic and earth abundant materials with superior optoelectronic features has led to the discovery of chalcogenide perovskites (CPs). These are unconventional semiconductors with the formula ABX3, where A and B are cations and X is a chalcogen, which covers the compounds with the corner sharing perovskite structures of type II-IV- VI3 compounds (II = Ba, Sr, Ca, Eu; IV = Zr, Hf; VI = S, Se) and III1-III2-VI3 compounds (III1 and III2 = Lanthanides, Y, Sc; VI = S, Se). The increased coordination and ionicity in these compounds contribute to their excellent charge transport properties and exceptionally high optical absorption coefficient (&gt; 105 cm−1). The present review encompasses theoretical analysis that provides electronic band structures and the orbital contributions that support the excellent optoelectronic properties. Furthermore, the challenging thin film deposition, characterizations, and their application in photodetection focusing on BaZrS3-which is the most studied one, are ascribed. Additionally, we suggest prospects that can bring out the true potential of these materials in photodetection and photovoltaics.

Tuning electronic structure and carrier transport properties through crystal orientation control in two-dimensional Dion-Jacobson phase perovskites

Two-dimensional halide perovskites are attracting attention due to their structural diversity, improved stability, and enhanced quantum efficiency compared to their three-dimensional counterparts. In particular, Dion-Jacobson (DJ) phase perovskites exhibit superior structural stability compared to Ruddlesden-Popper phase perovskites. The inherent quantum well structure of layered perovskites leads to highly anisotropic charge transport and optical properties. Therefore, controlling the preferred crystal orientation (parallel or perpendicular) is crucial for optimizing device performance. This work presents a rational strategy to control parallel and perpendicular crystal growth in C6N2H16PbI4 (4AMPPbI4)-based DJ phase perovskite thin films. We demonstrate that crystal orientation depends on crystal growth rates, which can be controlled by varying the solvent composition, antisolvent, and annealing temperature. Direct and inverse photoelectron spectroscopy reveals that the electronic structure of 4AMPPbI4, including its work function, ionization energy, and electron affinity, is orientation-dependent. Different orientations significantly affect carrier transport as confirmed by single-carrier devices. This study highlights the critical role of crystal orientation in DJ phase perovskites for designing high-performance optoelectronic devices.Graphical

Large Manipulation of Ferrimagnetic Curie Temperature by A-Site Chemical Substitution in ACu3Fe2Re2O12 (A = Na, Ca, and La) Half Metals.

CaCu3Fe2Re2O12 and LaCu3Fe2Re2O12 quadruple perovskite oxides are well known for their high ferrimagnetic Curie temperatures and half-metallic electronic structures. By A-site chemical substitution with lower valence state Na+, an isostructural compound NaCu3Fe2Re2O12 with both A- and B-site ordered quadruple perovskite structures in Pn-3 symmetry was prepared using high-pressure and high-temperature techniques. The X-ray absorption study demonstrates the valence states to be Cu2+, Fe3+, and Re5.5+. A ferrimagnetic phase transition is found to take place at the Curie temperature TC ≈ 240 K, which is much less than that observed in A = Ca (560 K) and La (710 K) analogues. NaCu3Fe2Re2O12 possesses a larger saturated magnetic moment up to 9.4 μB/f.u. as well as a remarkably reduced coercive field less than 10 Oe at 2 K. Theoretical calculations suggest that NaCu3Fe2Re2O12 displays a half-metallic electronic band structure with complete spin polarization of conduction electrons in the minority-spin bands. The magnetic properties and electronic structures of the ACu3Fe2Re2O12 family are compared and discussed.

Hydrogenation of Simulated Bio-Syngas in the Presence of GdBO3 (B = Fe, Co, Mn) Perovskite-Type Oxides

Direct light olefin synthesis from bio-syngas hydrogenation is a promising pathway to decarbonize the chemical industry. The present study is devoted to the investigation of co-hydrogenation of carbon oxides in the presence of complex systems with the perovskite structure GdBO3 (B = Fe, Mn, Co). The catalyst samples were synthesized by sol-gel technology and characterized by XRD, XPS, BET and TPR. It was found that the Fe/Mn-containing samples exhibited efficient catalysis of the hydrogenation of simulated bio-syngas to light hydrocarbons. The GdMnO3 catalyst exhibits selectivity for C2–C3 light olefins of up to 37% among C1+ hydrocarbons, with a maximum olefin/paraffin ratio. GdMnO3 also exhibits high conversion of CO and CO2, reaching up to 70–75% at 723 K. However, the GdFeO3 catalyst shows a lower selectivity of (C2−3= = 22%, while it exhibits a higher conversion of CO2, up to 95%, at the same temperature. Herein, we established a catalyst structure–performance relationship as a function of chemical composition. Oxygen mobilities and ratios of surface (Os) to lattice (Ol) oxygen, forms of hydrogen adsorption, formation of -CHx- radicals and their subsequent recombination to olefins are influenced by the nature of the element in the B position. This work provides valuable insights for the rational design of bimetallic catalysts for bio-syngas hydrogenation.

Improved Efficiency and Stability of Perovskite Solar Cells Through Long-Chain Phenylammonium Additives.

The addition of organic cationic iodides to form low-dimensional perovskite is an essential strategy for defect passivation in perovskite solar cells (PSCs). Specially, the 2D/3D perovskite structure can combine the stability of 2D perovskite and the high charge transport performance of 3D perovskite. Here, we introduced phenylammonium hydroiodide salts with different alkyl chain lengths into PSCs precursor solution to research the influence on formation of perovskite thin films and the photovoltaic performance of PSCs. As a result, the champion power conversion efficiency (PCE) of PSCs was increased to 22.68% by incorporation of the organic cation phenylpropyl ammonium iodide (PPAI) with the best alkyl chain length. We further fabricated the perovskite solar modules (PSMs) with an aperture area of 21 cm2, achieving an impressive efficiency of 21.65% with excellent stability that maintaining 89% of its initial efficiency after 1000 h of maximum power point tracking.

Optimizing the light-humidity stability of formamidinium halide perovskites through intermediate phase and strain stress adjustment

Recently, the FA1-xCsxPbI3 system became popular due to its high performance and respectful thermal stability. However, the impact of Cs doping in the precursor on the stability of FA1-xCsxPbI3 perovskite films and devices remains unclear. Here, we systematically investigate the effects of trace amounts of Cs+ cations (<10%) on the intermediate phase, the crystallization and orientation, lattice strain and device stability of FA1-xCsxPbI3 perovskite. The results demonstrate that 5.0% Cs+ cations substitution for FA reduces the nucleation barrier of FAPbI3 and promotes the formation of the α-phase before heat treatment. And the Cs+ cations induce the oriented growth of FA1-xCsxPbI3 perovskite, eliminating unfavorable (110) facet and preventing the formation of unstable (100) facet at the top of perovskite. Meanwhile, 5.0% Cs+ cation substitution for FA effectively alleviates lattice strains in the perovskite structure, minimizing defects or traps recombination centers. Thus, the light and humidity stability of the FA0.950Cs0.050PbI3 device are substantially increased. The PCE of FA0.950Cs0.050PbI3 device remains ∼70% of the initial value after 768 hours under humidity exposure, and as a comparison, the FAPbI3 maintains only 54.5% of the initial value. The pure FAPbI3 device only maintains ∼25% of its initial value under 14 light-dark cycles, while the FA0.950Cs0.050PbI3 device maintains ∼75.1% of its initial value after 18 light-dark cycles. This work highlights the optimal threshold for Cs+ cation substitution for FA in FA1-xCsxPbI3 perovskite, contributing to the advancement of FA1-xCsxPbI3 high-performance perovskite solar cells.

Room-temperature synthesis of triple-cation green perovskite quantum dots for optoelectronic applications.

The development of multi-cation perovskite quantum dots (PQDs) is limited by the low availability of fitting A-site cations due to the unsuitable radii of a large gamut of amine cations. The impact of oversized or undersized cations on the perovskite structure is detrimental to the structural stabilization and electroluminescence efficiency of the PQDs. Researchers are actively seeking suitable-sized cations to mitigate perovskite defect formation and optimize charge carrier confinement within the PQDs. In contrast to cesium (Cs) or formamidine (FA), which are exposed to degradation pathways, guanidinium (GA)-doping has been to provide a suitable radius and the lack a dipole moment. The triple nitrogen functionality of GA enables it to passivate both the PbBr6 octahedra and surface defects through vacant A-sites and entropically stabilize the perovskite. Furthermore, the insertion of GA into the PQD lattice is enthalpically facilitated by the presence and arrangement of smaller Cs and Br atoms. Herein, we have synthesized a Cs-FA PQD reference into which GA is doped via two chemical routes. Our triple-cation system exhibits substantially improved optical properties and was applied for the fabrication of a PeLED device. The optimized triple-cation PQDs-based PeLED device exhibited an external quantum efficiency of 5.87% and a luminescence of 13726 cd m-2.

Strategic design of emerging (K,Na)NbO3-based perovskites for high-performance piezocatalysis and photo-piezocatalysis.

As a leading Pb-free perovskite material (ABO3-type), potassium sodium niobate (K,Na)NbO3 (KNN)-based ferroelectrics/piezoelectrics have been widely used in electronics, energy conversion, and storage due to their exceptional ability to interconvert mechanical and electrical energies. Beyond traditional applications, the piezoelectric potential generated by mechanical strain or stress modifies their energy band structures and facilitates charge carrier separation and transport, drawing increasing attention in emerging fields such as piezocatalysis and photo-piezocatalysis. With excellent piezoelectric properties, chemical/thermal stability, and strain-tuning capability, KNN-based materials show great promise for high-performance piezocatalytic applications. Coupling KNN with semiconductors exhibiting strong optical absorption to form heterojunctions further boosts performance by suppressing electron-hole recombination and promoting directed charge transfer, which is crucial for photo-piezocatalysis. The flexibility of KNN's perovskite structures also allows for modifications in chemical composition and crystal structure, enabling diverse design strategies such as defect engineering, phase boundary engineering, morphology control, and heterojunction formation. This review comprehensively explores the recent advancements in KNN-based piezocatalysis and photo-piezocatalysis, starting with an overview of their crystal structures and intrinsic properties. It then explores the role of piezoelectric potential in charge carrier dynamics and catalytic activity, followed by strategic design approaches to optimize efficiency in environmental remediation and energy conversion. Finally, the review addresses current challenges and future research directions aimed at advancing sustainable solutions using KNN-based materials in these applications.

Fine-tuning of optical band gap in mixed halide aziridinium lead perovskites.

Hybrid halide perovskites form a promising class of light-absorbing materials. Among the numerous 3D semiconducting perovskites, there is a group of emerging aziridinium-based hybrids that are considered to be prospective materials for optoelectronic applications. In this work, we report the mixed halide aziridinium perovskites of (AzrH)PbBrxI3-x series (AzrH = aziridinium). Small changes in the composition of perovskites are shown to have a defining impact on the optoelectronic properties of the reported materials. Halogen substitution allowed a variation in band gap values of these compounds, ranging from 1.57 to 2.23 eV, as established using electronic spectroscopy. Crystal structures of (AzrH)PbBrxI3-x perovskites were studied using single crystal and powder X-ray diffraction analysis. The lattice constant had a linear dependence on the Br content in the structure, thus strictly following Vegards's law. Importantly, the reported compounds displayed a preferential inclusion of iodine upon synthesis, revealing that the mixed halide perovskite composition cannot be estimated based on the precursors' ratio only, and it should be post-synthetically checked. The reported results expand the range of hybrid perovskites with tuneable band gaps beyond the conventional methylammonium and formamidinium-based perovskites and offer a new series of metal-halide hybrids suitable for photovoltaic and other optoelectronic applications.

Recent progress of gas sensors based on perovskites.

Gas sensors convert gas-related information into usable data by monitoring changes in conductivity and chemical reactions resulting from the adsorption of gas molecules. Recently, perovskites have emerged as promising candidate materials for gas sensors, owing to their polar reactivity, chemical responsiveness, and sensitivity. These characteristics enable the detection of the presence and concentration of various gases. This article provides a concise review of recent advancements in perovskite-based gas sensors. First, the chemical composition, structure, and preparation methods of perovskites, as well as the effects of their structure on gas sensing performance, are examined. The key performance parameters of the sensor and the sensing mechanism of the perovskite-based gas sensor are discussed. Then the development of gas sensors based on different structural types of perovskites, including single-component perovskites, mixed-component perovskites, and metal-oxide perovskites, is discussed. Finally, the challenges and opportunities for gas sensors based on perovskites are summarized and prospected.

Preparation of (Ba0.25Ca0.25Sr0.25La0.25)Ti1-xAlxO3 High-Entropy Perovskite Ceramics for enhanced Microwave Dielectric Performance

Development of microwave dielectric ceramics with a high dielectric constant, high quality factor, and low temperature coefficient of resonant frequency is of great importance for achieving miniaturization, low loss, and high stability in microwave devices. Research on low dielectric constant microwave dielectric ceramics has made certain progress, but the development of new systems of high dielectric constant microwave dielectric ceramics with excellent overall performance is still in the exploratory stage. Herein, approaches of high-entropy strategy and small radius ions doping were combined to achieve high microwave dielectric properties. It is demonstrated that a high-entropy ceramic with a perovskite structure doped with Al3+ ion, denoted as (Ba0.25Ca0.25Sr0.25La0.25)Ti1-xAlxO3 (abbreviated as HESOs, 0<x≤0.25), was successfully synthesized. At x=0.1 and 1500oC, HESO exhibited optimized comprehensive dielectric performance, characterized by εr = 89.25, Q×f = 3304GHz, and τf = +361 ppm/oC. Besides, as the aluminum ion content increases, there is a reduction in grain size accompanied by an elevation in oxygen vacancy content, resulting in increase of Q×f, with a peak value reaching 4136GHz. This study presents a valuable exploration aimed at designing high-entropy perovskite ceramics with excellent dielectric properties.

Ga-doping in Li0.33La0.56TiO3: a promising approach to boost ionic conductivity in solid electrolytes for high-performance all-solid-state lithium-ion batteries.

All-solid-state lithium-ion batteries (ASSLBs) are the next advancement in battery technology which is expected to power the next generation of electronics, particularly electric vehicles due to their high energy density and superior safety. ASSLBs require solid electrolytes with high ionic conductivity to serve as a Li-ion battery, driving extensive research efforts to enhance the ionic conductivity of the existing solid electrolytes. Keeping this in view, the B-site of Li0.33La0.56TiO3 (LLTO) solid electrolyte has been partially substituted with Ga and novel Ga-doped LLTO (Li0.33+x La0.56Ti1-x Ga x O3) solid-electrolytes are fabricated using the solid-state reaction method, followed by sintering at 1100 °C for 2 h. The effects of Ga substitution on the structural changes, chemical states, ionic conductivity, and electrochemical stability of LLTO are systematically analyzed. The XRD analysis of the LLTO samples confirms the formation of a tetragonal perovskite structure and increasing bottleneck size up to 3% Ga-doped samples. XPS results have further confirmed the successful substitution of Ti4+ by Ga3+. The Ga3+ substitution has successfully enhanced the conductivity of LLTO solid electrolytes and the highest conductivity of 4.15 × 10-3 S cm-1 is found in Li0.36La0.56Ti0.97Ga0.03O3 (x = 0.03), which is an order of magnitude higher than that of pristine LLTO. This increase in ionic conductivity is a synergistic effect of B-O bond stretching resulting from the size difference between Ga3+ and Ti4+ and the increase in grain size. Moreover, the synthesized solid electrolytes are stable within the range of 2.28 to 3.78 V against Li/Li+, making them potential candidates for all-solid-state lithium-ion batteries.