Articles de revues : « Perovskites oxides »

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Mitchell, Roger H., Mark D. Welch et Anton R. Chakhmouradian. « Nomenclature of the perovskite supergroup : A hierarchical system of classification based on crystal structure and composition ». Mineralogical Magazine 81, n^o 3 (juin 2017) : 411–61. http://dx.doi.org/10.1180/minmag.2016.080.156.

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AbstractOn the basis of extensive studies of synthetic perovskite-structured compounds it is possible to derive a hierarchy of hettotype structures which are derivatives of the arisotypic cubic perovskite structure (ABX3), exemplified by SrTiO3 (tausonite) or KMgF3 (parascandolaite) by: (1) tilting and distortion of the BX6 octahedra; (2) ordering of A- and B-site cations; (3) formation of A-, B- or X-site vacancies. This hierarchical scheme can be applied to some naturally-occurring oxides, fluorides,hydroxides, chlorides, arsenides, intermetallic compounds and silicates which adopt such derivative crystal structures. Application of this hierarchical scheme to naturally-occurring minerals results in the recognition of a perovskite supergroup which is divided into stoichiometric and non-stoichiometricperovskite groups, with both groups further divided into single ABX3 or double A2BB'X6 perovskites. Subgroups, and potential subgroups, of stoichiometric perovskites include: (1) silicate single perovskites of the bridgmanite subgroup;(2) oxide single perovskites of the perovskite subgroup (tausonite, perovskite, loparite, lueshite, isolueshite, lakargiite, megawite); (3) oxide single perovskites of the macedonite subgroup which exhibit second order Jahn-Teller distortions (macedonite, barioperovskite); (4) fluoride singleperovskites of the neighborite subgroup (neighborite, parascandolaite); (5) chloride single perovskites of the chlorocalcite subgroup; (6) B-site cation ordered double fluoride perovskites of the cryolite subgroup (cryolite, elpasolite, simmonsite); (7) B-site cation orderedoxide double perovskites of the vapnikite subgroup [vapnikite, (?) latrappite]. Non-stoichiometric perovskites include: (1) A-site vacant double hydroxides, or hydroxide perovskites, belonging to the söhngeite, schoenfliesite and stottite subgroups; (2) Anion-deficient perovskitesof the brownmillerite subgroup (srebrodolskite, shulamitite); (3) A-site vacant quadruple perovskites (skutterudite subgroup); (4) B-site vacant single perovskites of the oskarssonite subgroup [oskarssonite]; (5) B-site vacant inverse single perovskites of the coheniteand auricupride subgroups; (6) B-site vacant double perovskites of the diaboleite subgroup; (7) anion-deficient partly-inverse B-site quadruple perovskites of the hematophanite subgroup.

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Feng, Dawei, et Alexandra Navrotsky. « Thermochemistry of Rare Earth Perovskites ». MRS Advances 1, n^o 38 (2016) : 2695–700. http://dx.doi.org/10.1557/adv.2016.489.

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AbstractThe rare earth (RE) mineral loparite with the chemical composition (RE, Na, Sr, Ca)(Ti, Nb, Ta, Fe+3)O3 is the principal ore of the light rare earth elements (LREE) as well as niobium and tantalum. The enthalpies of formation of RE0.67-xNa3xTiO3 (RE = La, Ce) and Ca1-2xNaxLaxTiO3 from oxides and elements of lanthanum and cerium perovskites and their solid solutions have been obtained using high temperature oxide melt solution calorimetry. RE0.67-xNa3xTiO3 (RE = La, Ce) perovskites become more stable relative to oxide components as sodium content increases. Na0.5Ce0.5TiO3 and Na0.5La0.5TiO3 can be considered stable endmembers in natural loparite minerals. For perovskite solid solutions Ca1-2xNaxLaxTiO3, the enthalpies of formation from the constituent oxides $\Delta {\rm{H}}_{{\rm{f}},\,{\rm{ox}}}^^\circ$ become more exothermic with increasing Na+La content, suggesting a stabilizing effect of the substitution 2Ca2+ → Na+ + La3+ on the perovskite structure. The trend of increasing thermodynamic stability with decreasing structural distortion is similar to that seen in many other ABO3 perovskites.

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Han, Binghong, et Yang Shao-Horn. « (Invited) In-Situ Study of the Activated Lattice Oxygen Redox Reactions in Metal Oxides during Oxygen Evolution Catalysis ». ECS Meeting Abstracts MA2018-01, n^o 32 (13 avril 2018) : 1935. http://dx.doi.org/10.1149/ma2018-01/32/1935.

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Promoting the oxygen evolution reaction (OER) near room temperature is critical to improve the efficiency of many electrochemical energy storage and conversion techniques, such as water splitting and rechargeable metal-air batteries. Nowadays, researchers have developed many non-precious metal oxides as highly active OER catalysts, including many perovskite oxides (ABO3) of first-row transition metals such as LaCoO3-δ (LCO), SrCoO3-δ (SCO), and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF). However, understanding the interaction between oxides catalysts and water, which determines the stability and activity of the oxide OER catalysts, is still challenging. Here we report the systematic investigation between water and various perovskite oxides with different electronic structures, using a series of in situ characterization techniques including on-line electrochemical mass spectrometry (OLEMS), environmental transmission electron microscopy (ETEM), and pH-dependent electrochemical tests. It is find that having an oxygen 2p-band closer to the Fermi level and increasing the covalency of metal-oxygen bonds could facilitate the redox reaction of lattice oxygen in perovskites during OER catalysis. In the oxides such as SCO and BSCF with activated lattice oxygen in the OER process, we observe the evolving of 18O-labeled lattice oxygen in OLEMS, the strong pH dependency of OER kinetics in electrochemical measurements, and the structural oscillation in ETEM, which all indicate a new oxygen-site OER mechanism that makes the perovskites more active and less stable. While in the oxides such as LCO with no lattice oxygen activation, all of the above phenomena are missing, implying a stable surface with traditional metal-site OER mechanism. Observing the perovskites in situ during OER allows us to better understand the interaction between electrolytes and oxides, providing us a deeper insight into the stability and active site of oxide catalysts for OER.

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Mistri, Rajib. « Catalytic Organic Reactions in Liquid Phase by Perovskite Oxides : A Review ». Asian Journal of Chemistry 34, n^o 10 (2022) : 2489–98. http://dx.doi.org/10.14233/ajchem.2022.23976.

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The structural flexibility and controllable physico-chemical characters of perovskite oxides have drawn major attention of researchers for catalytic reactions. Perovskite oxide are mainly used as catalysts for electrochemical, high temperature gas-phase and photocatalytic reactions but their uses for catalytic organic reactions in liquid phase are limited. Various porous and nano-perovskite oxides have been prepared by different methods are effectively used as catalyst for different types of organic reactions in liquid phase. The liquid-phase catalytic organic reactions over perovskite oxides have been classified mainly into three groups: (i) acid/base catalyzed, (ii) selective oxidation and (iii) cross-coupling reactions. This review article mainly emphases on different examples of perovskite oxides catalyzed organic reactions in liquid phase along with the relationships among the unique catalytic performance with the structural and the physico-chemical properties of perovskites.

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Gazda, M., P. Jasinski, B. Kusz, B. Bochentyn, K. Gdula-Kasica, T. Lendze, W. Lewandowska-Iwaniak, A. Mielewczyk-Gryn et S. Molin. « Perovskites in Solid Oxide Fuel Cells ». Solid State Phenomena 183 (décembre 2011) : 65–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.183.65.

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Perovskite oxides comprise large families among the structures of oxide compounds, and several perovskite-related structures are also known. Because of their diversity in chemical composition, properties and high chemical stability, perovskite oxides are widely used for preparing solid oxide fuel cell (SOFC) components. In this work a few examples of perovskite cathode and anode materials and their necessary modifications were shortly reviewed. In particular, nickel-substituted lanthanum ferrite and iron-substituted strontium titanate as cathode materials as well as niobium-doped strontium titanate, as anode material, are described. Electrodes based on the modified perovskite oxides are very promising SOFC components.

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Bartel, Christopher J., Christopher Sutton, Bryan R. Goldsmith, Runhai Ouyang, Charles B. Musgrave, Luca M. Ghiringhelli et Matthias Scheffler. « New tolerance factor to predict the stability of perovskite oxides and halides ». Science Advances 5, n^o 2 (février 2019) : eaav0693. http://dx.doi.org/10.1126/sciadv.aav0693.

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Predicting the stability of the perovskite structure remains a long-standing challenge for the discovery of new functional materials for many applications including photovoltaics and electrocatalysts. We developed an accurate, physically interpretable, and one-dimensional tolerance factor, τ, that correctly predicts 92% of compounds as perovskite or nonperovskite for an experimental dataset of 576 ABX3 materials (X = O2−, F−, Cl−, Br−, I−) using a novel data analytics approach based on SISSO (sure independence screening and sparsifying operator). τ is shown to generalize outside the training set for 1034 experimentally realized single and double perovskites (91% accuracy) and is applied to identify 23,314 new double perovskites (A2BB′X6) ranked by their probability of being stable as perovskite. This work guides experimentalists and theorists toward which perovskites are most likely to be successfully synthesized and demonstrates an approach to descriptor identification that can be extended to arbitrary applications beyond perovskite stability predictions.

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Ferri, Davide. « Catalysis by Metals on Perovskite-Type Oxides ». Catalysts 10, n^o 9 (15 septembre 2020) : 1062. http://dx.doi.org/10.3390/catal10091062.

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Perovskites are currently on everyone’s lips and have made it in high-impact scientific journals because of the revolutionary hybrid organic–inorganic lead halide perovskite materials for solar cells [...]

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Padha, Bhavya, Sonali Verma, Prerna Mahajan et Sandeep Arya. « Role of Perovskite-Type Oxides in Energy Harvesting Applications ». ECS Transactions 107, n^o 1 (24 avril 2022) : 12073–81. http://dx.doi.org/10.1149/10701.12073ecst.

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Perovskite type oxide (PTO) is an extensively studied material over the past decade. Deformations occur as a consequence of variances in their ionic radii and electronegativity, which come from the production of oxygen or cation deficiencies, or alterations in their respective bonding angles. The perovskites' defects and order–disorder crystal structures result in a wide range of functional characteristics. This paper reviews the contribution of perovskite-based oxides in these applications. In this context, the future scope of these materials has been investigated to enhance the performance parameters like specific capacity, power conversion efficiency, energy density, and cycle life. This research will aid in the selection of suitable perovskite materials.

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Kirichenko, Evgeny A., Pavel G. Chigrin et Anton A. Gnidenko. « Synthesis of YFeO_3-δ and LaFeO_3-δ Perovskites with High Catalytic Activity in Carbon Oxidation Reactions ». Solid State Phenomena 316 (avril 2021) : 105–9. http://dx.doi.org/10.4028/www.scientific.net/ssp.316.105.

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YFeO3-δ (δ = 0.26) and LaFeO3-δ (δ = 0.5) perovskites with a high specific surface and oxygen non-stoichiometry was firstly synthesized by pyrolysis of polymer-salt compositions. It was shown that the catalytic oxidation of carbon in the presence of these complex oxide systems proceeds in the range of 400 - 700 °С, with a maximum temperature at 556 °С for YFeO3-δ; and 380 - 620 °С ,with a maximum temperature at 501 °С for LaFeO3-δ, in one-stage mode for both. By means of thermal analysis and diffractometry, it was shown that there is no contribution to the soot oxidation mechanism by cyclic perovskite surface transformations, due to the reduction of metal oxides by the soot and their subsequent reoxidation. It has been established that the basis of the catalytic reaction mechanism for both perovskites is the presence of oxygen vacancies on the surface of complex oxides.

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Jetpisbayeva, G. D., B. K. Massalimova et A. B. Daulet. « SYNTHESIS OF PEROFSKITE-LIKE Co-CONTAINING CATALYST ». SERIES CHEMISTRY AND TECHNOLOGY 2, n^o 440 (15 avril 2020) : 115–19. http://dx.doi.org/10.32014/2020.2518-1491.31.

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There are several approaches to the preparation of catalysts with a developed surface based on oxides with a perovskite structure. Perovskites, due to the possibility of easy variation of chemical composition, make it possible to choose the optimal composition of the catalyst and surface area, and as a result it is possible to influence effectively the selectivity. Perovskite-like LaMeO3 oxides are one of the most promising catalysts for many oxidation processes due to their high activity in oxidative reactions and the stability in aggressive environment. Pekini method (polymer complexes method) and its simplified variant - citrate method are the most widely used for the synthesis of perovskite-like oxides. This article reports about the synthesis of perovskite-like complex oxide LaCoO3 obtained in two ways: hydrothermal, using ethylene glycol, and the citrate method using the template – mesoporous silica KIT-6. The structure of the samples obtained was determined by the XRD method. As a result, it was found that the catalysts have a perovskite structure. Key words: LaCoO3 , perovskite, KIT-6.

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Förster, Stefan, Eva Zollner, Klaus Meinel, Renè Hammer, Martin Trautmann et Wolf Widdra. « 2D quasicrystals from perovskites ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C80. http://dx.doi.org/10.1107/s2053273314099197.

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Perovskite oxides represent a versatile class of materials with a simple cubic or pseudo-cubic crystal structure. The family of perovskite oxides contains insulators, metals, semiconductors, and superconductors with nearly identical lattice parameters. This structural equivalence additionally allows to combine perovskites with different properties in multilayer systems to produce functional materials with unique properties. We report here on the formation of a quasicrystal (QC) thin film on a threefold Pt(111) surface. This QC film is derived from the classical perovskite oxide BaTiO3 which is the most intensely studied ferroelectric perovskite oxide. An easily accessible ferroelectric to paraelectric phase transition at 400 K makes the material so interesting for basic and applied research. Due to matching lattice conditions BaTiO3 can be grown epitaxially on selected metal substrates. Periodic thin films of either BaTiO3(100) or BaTiO3(111) have been grown depending on substrate orientation and preparation conditions on Pt(001) and on Pt(111) [1, 2]. As we demonstrate here, astonishingly also a two-dimensional dodecagonal quasicrystalline structure can be formed by annealing an initially 1.4 nm thick BaTiO3 film on Pt(111) [3]. It develops at a temperature of 1250 K from a wetting layer spreading between a few thicker BaTiO3(111) islands. Surface sensitive electron diffraction (LEED) shows a bright and sharp pattern with dodecagonal symmetry. High-resolution scanning tunneling microscopy (STM) images reveal an arrangement of quadratic, triangular, and rhombic elements which compares well to a Gähler tiling. The development of higher-order self-similar structures is widely suppressed by a linear phason strain. This is supported by the fine structure of the diffraction data.

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Rodgers, Jennifer A., Anthony J. Williams et J. Paul Attfield. « High-pressure / High-temperature Synthesis of Transition Metal Oxide Perovskites ». Zeitschrift für Naturforschung B 61, n^o 12 (1 décembre 2006) : 1515–26. http://dx.doi.org/10.1515/znb-2006-1208.

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Perovskite and related Ruddlesden-Popper type transition metal oxides synthesised at high pressures and temperatures during the last decade are reviewed. More than 60 such new materials have been reported since 1995. Important developments have included perovskites with complex cation orderings on A and B sites, multiferroic bismuth-based perovskites, and new manganites showing colossal magnetoresistance (CMR) and charge ordering properties.

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Sawaguri, Hiroki, Daichi Yasuhara et Nobuyuki Gokon. « Redox Performance and Optimization of the Chemical Composition of Lanthanum–Strontium–Manganese-Based Perovskite Oxide for Two-Step Thermochemical CO2 Splitting ». Processes 11, n^o 9 (11 septembre 2023) : 2717. http://dx.doi.org/10.3390/pr11092717.

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The effects of substitution at the A- and B sites on the redox performance of a series of lanthanum–strontium–manganese (LSM)-based perovskite oxides (Z = Ni, Co, and Mg) were studied for application in a two-step thermochemical CO2 splitting cycle to produce liquid fuel from synthesis gas using concentrated solar radiation as the proposed energy source and CO2 recovered from the atmosphere as the prospective chemical source. The redox reactivity, stoichiometry of oxygen/CO production, and optimum chemical composition of Ni-, Co-, and Mg-substituted LSM perovskites were investigated to enhance oxygen/CO productivity. Furthermore, the long-term thermal stabilities and thermochemical repeatabilities of the oxides were evaluated and compared with previous data. The valence changes in the constituent ionic species of the perovskite oxides were studied and evaluated by X-ray photoelectron spectroscopy (XPS) for each step of the thermochemical cycle. From the perspectives of high redox reactivity, stoichiometric oxygen/CO production, and thermally stable repeatability in long-term thermochemical cycling, Ni0.20-, Co0.35-, and Mg0.125-substituted La0.7Sr0.3Mn perovskite oxides are the most promising materials among the LSM perovskite oxides for two-step thermochemical CO2 splitting, showing CO productivities of 387–533 μmol/g and time-averaged CO productivities of 12.9–18.0 μmol/(min·g) compared with those of LSM perovskites reported in the literature.

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Cascos, V., R. Martínez-Coronado, M. T. Fernández-Díaz et J. A. Alonso. « Topotactic Oxidation of Perovskites to Novel SrMo1-xMxO4−δ (M = Fe and Cr) Deficient Scheelite-Type Oxides ». Materials 13, n^o 19 (6 octobre 2020) : 4441. http://dx.doi.org/10.3390/ma13194441.

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New polycrystalline SrMo1−xMxO4−δ (M = Fe and Cr) scheelite oxides have been prepared by topotactical oxidation, by annealing in air at 500 °C, from precursor perovskites with the stoichiometry SrMo1−xMxO3−δ (M = Fe and Cr). An excellent reversibility between the oxidized Sr(Mo,M)O4−δ scheelite and the reduced Sr(Mo,M)O3−δ perovskite phase accounts for the excellent behavior of the latter as anode material in solid-oxide fuel cells. A characterization by X-ray powder diffraction (XRD) and neutron powder diffraction (NPD) has been carried out to determine the crystal structure features. The scheelite oxides are tetragonal, space group I41/a (No. 88). The Rietveld-refinement from NPD data at room temperature shows evidence of oxygen vacancies in the structure, due to the introduction of Fe3+/Cr4+ cations in the tetrahedrally-coordinated B sublattice, where Mo is hexavalent. A thermal analysis of the reduced perovskite (SrMo1−xMxO3−δ) in oxidizing conditions confirms the oxygen stoichiometry obtained by NPD data; the stability range of the doped oxides, below 400–450 °C, is lower than that for the parent SrMoO3 oxide. The presence of a Mo4+/Mo5+ mixed valence in the reduced SrMo1−xMxO3−δ perovskite oxides confers greater instability against oxidation compared with the parent oxide. Finally, an XPS study confirms the surface oxidation states of Mo, Fe, and Cr in the oxidized samples SrMo0.9Fe0.1O4-δ and SrMo0.8Cr0.2O4-δ.

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Bhavyasree, A. B., K. P. Latha et H. S. Jayanna. « Photocatalytic activity of Perovskites for degradation of dyes ». Research Journal of Chemistry and Environment 25, n^o 9 (25 août 2021) : 146–50. http://dx.doi.org/10.25303/259rjce146150.

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Perovskites are mixed metal-oxides which have received much attention and more applicative interests in the research field as well as in industry due to their unique properties like high surface area, small size, excellent magnetic property, thermal stability and low price. Perovskites are effectively used as semiconductors, adsorbents, catalyst, Superconductors etc. The present study outlined the broad overview of the Perovskite as photocatalyst.

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Peng, Bo, Yuchen Hu, Shuichi Murakami, Tiantian Zhang et Bartomeu Monserrat. « Topological phonons in oxide perovskites controlled by light ». Science Advances 6, n^o 46 (novembre 2020) : eabd1618. http://dx.doi.org/10.1126/sciadv.abd1618.

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Perovskite oxides exhibit a rich variety of structural phases hosting different physical phenomena that generate multiple technological applications. We find that topological phonons—nodal rings, nodal lines, and Weyl points—are ubiquitous in oxide perovskites in terms of structures (tetragonal, orthorhombic, and rhombohedral), compounds (BaTiO3, PbTiO3, and SrTiO3), and external conditions (photoexcitation, strain, and temperature). In particular, in the tetragonal phase of these compounds, all types of topological phonons can simultaneously emerge when stabilized by photoexcitation, whereas the tetragonal phase stabilized by thermal fluctuations only hosts a more limited set of topological phonon states. In addition, we find that the photoexcited carrier concentration can be used to tune the topological phonon states and induce topological transitions even without associated structural phase changes. Overall, we propose oxide perovskites as a versatile platform in which to study topological phonons and their manipulation with light.

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Nomura, Katsuhiro, Masakazu Daté, Hiroyuki Kageyama et Susumu Tsubota. « Ultramarine colored : Solid-phase elution of Pt into perovskite oxides ». Journal of Materials Research 22, n^o 10 (octobre 2007) : 2647–50. http://dx.doi.org/10.1557/jmr.2007.0340.

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We have found a new route for preparing Pt containing perovskites. Ba containing perovskite powder, (La0.7Sr0.2Ba0.1)ScO3–δ (LSBS), reacted with Pt foil at 1898 K in air, and formed ultramarine colored Pt containing perovskite, (La0.7Sr0.2Ba0.1)(Sc,Pt)O3–δ, without changing the GdFeO3-type structure. The chemical compositions of the samples before and after firing, measured with inductively coupled plasma (ICP) optical emission spectrometry, were La: Sr: Ba: Sc = 0.70(1): 0.206(4): 0.101(2): 0.98(2) and La: Sr: Ba: Sc: Pt = 0.70(1): 0.197(4): 0.085(2): 0.95(2): 0.0062(2), respectively. The reaction proceeded not only at the interface between perovskite powder and Pt foil, but also over whole powder surface. We name this new preparation method the “solid-phase elution (SE) method”, because the process involves elution of Pt ions from the Pt foil to the LSBS perovskite lattice. It is expected that we can control the amount of Pt introduced into perovskites by using the SE method after optimizing the reaction time and temperature.

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Kobayashi, Yoji, Yoshihiro Tsujimoto et Hiroshi Kageyama. « Property Engineering in Perovskites via Modification of Anion Chemistry ». Annual Review of Materials Research 48, n^o 1 (juillet 2018) : 303–26. http://dx.doi.org/10.1146/annurev-matsci-070317-124415.

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Perovskite-type oxides have proven to be a versatile class of compounds with systematic study of their structure and various properties. Further structural variations and properties can be added by adding a second anionic species other than oxide, such as hydride, fluoride, nitride, or others. The different charge, covalency, size, and new modes of local coordination offer convenient ways to further control carrier doping, magnetism, conductivity, and even chemical reactivity. In this review we examine the recent work concerning various mixed-anion perovskites and conclude with potential new directions for the further development of these materials.

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Barrera, A., M. L. Chávez, E. Chavira, T. A. García et J. M. E. Carreto. « Perovskite gels combustion synthesis from rare earth aluminates. Development of multifuncional properties. » MRS Advances 5, n^o 62 (2020) : 3301–13. http://dx.doi.org/10.1557/adv.2020.444.

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AbstractThe purpose of this work was the synthesis of the perovskites with rare earth, by gel combustion method with pigmenting, magnetic and luminescent properties. The synthesis of perovskite structure is important for material development, with multi features. In this work, the synthesis was from metal oxides by the method of combustion of gels at 500 °C, for 10 s. Color of perovskites obtained, with nanometric particle size (31-44 nm) was analysed by CIEL*a*b* with tonalities ranged from white to pink except for Pr-perovskites with yellow and brown. Its paramagnetic properties were verified by magnetic susceptibility. Its luminescence was at 260 nm, except for Pr-perovskites. This work opens an important opportunity to develop ceramic pigments with perovskites structures integrating other properties as luminescence and paramagnetism by combustion sol-gel method.

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Li, Meng, et Dong Ding. « Accelerated Discovery of Proton-Conducting Perovskites through Density Functional Theory and Machine Learning ». ECS Meeting Abstracts MA2022-02, n^o 49 (9 octobre 2022) : 1913. http://dx.doi.org/10.1149/ma2022-02491913mtgabs.

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Hydrogen is an important energy carrier resource in response to limiting greenhouse gas emissions. Proton-conducting perovskite oxide is one of the key materials for highly efficient carbon-neutral hydrogen technologies, such as hydrogen production, CO2 hydrogenation, and ammonia synthesis. Many attempts have been made based on doped perovskites made of well-tested materials, such as BaZrO3, BaCeO3, BaHfO3, BaTiO3, and SrZrO3. However, the resulting perovskites have often suffered stability and conductivity problems. Furthermore, complex phenomena occurring during hydration present challenges for expanding the materials library. Herein, we demonstrate accelerated discovery of proton-conducting perovskites with high conductivity using machine learning (ML) predictions. We constructed consistent training data using density functional theory (DFT) which enable high accuracy of ML model. DFT computations were performed on > 1000 doped perovskite compositions to get their properties of lattice parameters, point defects (e.g., O vacancies, H interstitials), density of states, hydration energy, and proton migration energy. Several ML algorithms including Linear Regression, Bayesian Ridge Regression, Random Forest Regression, Neural networks, and k-Nearest Neighbor were tested for minimum errors and coefficient of determination. The multidimensional relationships between a set of >50 features and conductivity were mapped out using the optimized ML model. We screened a large material space of A-site and B-site doped perovskites to predict potential proton-conducting materials for various energy applications. The outcomes are promising for accelerating the design and applications of proton-conducting perovskite oxides in hydrogen technologies.

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Cheng, Jihong, et Alexandra Navrotsky. « Enthalpies of formation of LaBO3perovskites (B = Al, Ga, Sc, and In) ». Journal of Materials Research 18, n^o 10 (octobre 2003) : 2501–8. http://dx.doi.org/10.1557/jmr.2003.0348.

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Enthalpies of formation from constituent oxides and elements at 298 K were determined by high-temperature oxide melt solution calorimetry for a group of technologically important perovskites LaBO3(B = La, Ga, Sc, and In). Enthalpies of formation from oxides of LaAlO3and LaGaO3are −69.61 ± 3.23 kJ/mol and −52.39 ± 1.99 kJ/mol, respectively. The data were consistent with literature values obtained using other methods. The enthalpies of formation of LaScO3and LaInO3from oxides were reported for the first time as −38.64 ± 2.30 kJ/mol and −23.99 ± 2.31 kJ/mol, respectively. As seen for other perovskites, as the tolerance factor deviates more from unity (in the order Al, Ga, Sc, In), the enthalpy of formation from oxides becomes less exothermic, indicating a less stable structure with respect to the constituent oxides.

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Zhao, Tingting, Haoran Yu, Xuyingnan Tao, Feiyang Yu, Ming Li et Haiqian Wang. « Influences of Ni Content on the Microstructural and Catalytic Properties of Perovskite LaNixCr1−xO3 for Dry Reforming of Methane ». Catalysts 12, n^o 10 (29 septembre 2022) : 1143. http://dx.doi.org/10.3390/catal12101143.

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Perovskite oxides were widely used as precursors for developing metal-support type catalysts. It is attractive to explore the catalytic properties of the oxides themselves for dry reforming of methane (DRM). We synthesized LaNixCr1−xO3 (x = 0.05–0.5) samples in powder form using the sol-gel self-combustion method. Ni atoms are successfully doped into the LaCrO3 perovskite lattice. The perovskite grains are polycrystalline, and the crystallite size decreases with increasing Ni content. We demonstrated that the LaNixCr1−xO3 perovskites show intrinsically catalytic activity for DRM reactions. Reducing the Ni content is helpful to reduce carbon deposition resulting from the metal Ni nanoparticles that usually coexist with the highly active perovskite oxides. The CH4 conversion over the LaNi0.1Cr0.9O3 sample reaches approximately 84% at 750 °C, and the carbon deposition is negligible.

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Sharma, Anupam Deep, et M. M. Sinha. « Lattice Dynamics of Protonic Conductors AZrO₃ (A = Ba, Sr & ; Pb) : A Comparative Study ». Advanced Materials Research 685 (avril 2013) : 191–94. http://dx.doi.org/10.4028/www.scientific.net/amr.685.191.

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Recently, many investigations were devoted to the study of family of perovskite-type ABO3oxides. The material belongs to ABO3 perovskite oxides family like SrZrO3, BaZrO3, PbZrO3have many characteristics which are suitable for high-voltage and high-reliability capacitor applications. Many acceptor-doped perovskite-type oxides show high protonic conductivity at elevated temperatures. In addition to their reduced temperature operation relative to traditional oxide ion conductors such as Y-stabilized ZrO2, these perovskites, because of their proton transport properties, offer the possibility of application in a number of arenas including hydrogen sensors for molten metals and hydrogen pumps. In this work we are reporting the results of our theoretical investigation on the phonon properties of ABO3mainly BaZrO3, PbZrO3& SrZrO3in cubic phases. The phonon properties are calculated by using lattice dynamical simulation method based on de Launey angular force (DAF) constant model to understand the role of phonon in these systems. The phonon dispersion curves of these proton conductors in cubic phase are also drawn.

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Cheng, Jihong, Alexandra Navrotsky, Xiao-Dong Zhou et Harlan U. Anderson. « Enthalpies of Formation of LaMO3 Perovskites (M = Cr, Fe, Co, and Ni) ». Journal of Materials Research 20, n^o 1 (janvier 2005) : 191–200. http://dx.doi.org/10.1557/jmr.2005.0018.

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Enthalpies of formation from constituent oxides and elements at 298 K were determined by high-temperature oxide melt solution calorimetry for a group of technologically important perovskites LaMO3 (M = Cr, Fe, Co, and Ni). The enthalpies of formation of LaCrO3 and LaFeO3 from oxides (La2O3 and Cr2O3 or Fe2O3) are –70.06 ± 2.79 kJ/mol and –64.58 ± 2.32 kJ/mol, respectively. The enthalpies of formation of LaCoO3 and LaNiO3 from oxides (La2O3 and CoO or NiO) and O2 are −107.64 ± 1.77 kJ/mol and –57.31 ± 2.55 kJ/mol, respectively. All these data are evaluated and found to be consistent with literature values obtained using other methods. The relative stability among these four perovskites decreases in the order of Cr, Fe, Co, Ni.

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Sun, Qiang, Zhong Wang, Da Wang, Zhe Hong, Mingdong Zhou et Xuebing Li. « A review on the catalytic decomposition of NO to N2 and O2 : catalysts and processes ». Catalysis Science & ; Technology 8, n^o 18 (2018) : 4563–75. http://dx.doi.org/10.1039/c8cy01114a.

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Recent advances in the catalytic decomposition of NO have been overviewed and divided into three categories: metal oxide catalysts (including perovskites and rare earth oxides), supported metal oxide catalysts (including alkali metals, cobalt oxide and noble metals) and Cu-ZSM-5.

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Yu, Xiu Ling, et Xue Li. « Synthesis, Electrical Conductivity and Electrochemical Properties of SrFe₁₋_xSb_xO₃₋_δ as Cathode Materials for IT-SOFCs ». Applied Mechanics and Materials 672-674 (octobre 2014) : 696–99. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.696.

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Fe-based perovskite oxides SrFe1-xSbxO3-δ (SFS, x = 0.05–0.15) have been prepared by a solid-state reaction and studied as novel cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFCs). As SOFC cathodes, the highest electrical conductivity of 100 S cm−1 at 425 oC in air was obtained for the x = 0.05 sample. The area-specific resistances of the SFS ( x = 0.05) cathode on the LSGM electrolyte where at 700 oC is 0.17 Ω cm2. All these results demonstrates that Sb-substituted SFS perovskites materials are promising cheaper alternative cathodes for an IT-SOFC.

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Liu, Zhengrong, Yueyue Sun, Jiaming Yang, Lei Fu, Jun Zhou et Kai Wu. « Tuning Exsolution of Nanoparticles in Defect Engineered Ruddlesden–Popper oxides for efficient CO₂ electrolysis ». ECS Meeting Abstracts MA2023-01, n^o 26 (28 août 2023) : 1709. http://dx.doi.org/10.1149/ma2023-01261709mtgabs.

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Solid oxide cell (SOC) is the energy conversion device with a series of advantages such as high efficiency, environmental friendliness and durability, making it a promising way to deal with environmental pollution and energy crisis appearing with the development of human society. Perovskite oxides with hetero-phases which were prepared by in-situ exsolution are widely used as fuel electrode in SOC. In this work, Ni-doped perovskites Ruddlesden–Popper oxides, (La, Sr)nTinO3n-2 with n = 5, 8, and 12 (LSTNn), were synthesized to design novel exsolution materials as solid oxide fuel cell anodes and for electrochemical catalysis applications. Compared with pure LSTNn without Ni, a small A-site deficiency (10%) promoted the exsolution of Ni from the perovskite oxides of Ni-doped LSTNn. It is found that the morphology as well as electrochemical activity of LSTNn anodes can be successfully manipulated by the exsolution of Ni. Since more Ni nanoparticles are exsolved from the parent oxides, LSTN8 displays better electrochemical performance by providing more active sides during the hydrogen oxidation reaction and significantly lowering electrode polarization resistance. DRT analysis is conducted to study substeps of the whole electrode reaction, finding that in-situ precipitation improves rate-limiting steps much. The CO2 reduction reaction performance of LSTN materials is also studied, finding that in-situ grown nanoparticles on surface of LSTN significantly increases the density of surface active sites and three phase boundaries (TPBs), which are beneficial for CO2 adsorption and subsequent conversion. It is clear from these results that varying Ni-doping in Ruddlesden–Popper oxides is a key factor in controlling the electrochemical performance and catalytic activity for hydrogen oxidation reaction in solid oxide fuel cells.

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Yan, Aiyu, Bin Liu, Baofeng Tu, Yonglai Dong, Mojie Cheng, Shuqin Song et Panagiotis Tsiakaras. « A Temperature-Programmed-Reduction Study on La1−xSrxCrO3 and Surface-Ruthenium-Modified La1−xSrxCrO3 ». Journal of Fuel Cell Science and Technology 4, n^o 1 (13 juin 2006) : 79–83. http://dx.doi.org/10.1115/1.2393308.

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A series of La1−xSrxCrO3(0⩽x⩽0.3) composite oxides were prepared by a modified citric method. These perovskite oxides were further modified with Ru through impregnation. X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and temperature-programmed-reduction (TPR) techniques were adopted to investigate the properties of both the as-prepared perovskite oxides and the surface-Ru-modified La1−xSrxCrO3 samples. XPS results indicated the existence of Cr6+ ions in the fresh samples and transformed to Cr3+ after reduction. The hydrogen consumed by these perovskite oxides during TPR increased with the Sr doping, which was more than twice of the theoretical value according to Kröger-Vink notation. The reduction temperature of Cr ions of Ru∕La1−xSrxCrO3 significantly decreased with an increase of the Ru loading. A small reduction peak at ∼540°C, which was not shifted by increasing Ru loadings, was observed and could be ascribed to the reduction of trace chromate phases. On all TPR profiles of the three doped perovskites with unity of the A-site and B-site ratio, the reduction of Ru species could not be observed at low Ru loadings (0.05% and 0.1%). A reduction peak from RuO2 particles appeared at temperatures prior to the perovskite reduction on the TPR plots of modified La0.9Sr0.1CrO3 and La0.8Sr0.2CrO3 with high Ru loading (0.5% and 1%, respectively), but it did not occur with the Ru modified La0.7Sr0.3CrO3 in the investigated Ru loading range. The TPR results of the Ru modified La0.8Sr0.2Cr0.95O3 depicted that some Ru ions might be stabilized due to the incorporation into the oxide.

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Avdeev, Maxim, El'ad N. Caspi et Sergey Yakovlev. « On the polyhedral volume ratios VA /VB in perovskites ABX 3 ». Acta Crystallographica Section B Structural Science 63, n^o 3 (16 mai 2007) : 363–72. http://dx.doi.org/10.1107/s0108768107001140.

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This paper presents analytical expressions for the calculation of ratios of cation coordination polyhedra volumes (VA /VB ) for perovskites ABX 3 of the Stokes–Howard diagram directly from atomic coordinates. We show the advantages of quantifying perovskite structure distortion with polyhedral volume ratios rather than with tilting angles, and discuss why space groups with multiple crystallographically inequivalent A or B sites (I4/mmm, Immm, P42/nmc etc.) are much less common than those with a single A and B site (I4/mcm, R\bar 3c, Pnma etc.). Analysis of crystallographic data for approximately 1300 perovskite structures of oxides, halides and chalcogenides from the Inorganic Crystal Structure Database revealed that the most highly distorted perovskites belong to the space group Pnma and formally lower-symmetry perovskites (I2/m, I2/a) are less distorted geometrically. Critical values of the VA /VB ratios for the most common phase transitions Pnma ↔ I4/mcm and Pnma↔ R\bar 3c are estimated to be ∼ 4.85 with the possible intermediate space group Imma stable in the very narrow range of VA /VB ≃ 4.8–4.9. Transitions to post-perovskite CaIrO3-type structures may be expected for VA /VB < 3.8.

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Egorova, Anastasia V., Ksenia G. Belova, Anzhelika O. Bedarkova, Irina E. Animitsa et Nataliia A. Tarasova. « Features of proton transport in BaLa0.9M0.1InO4 (M = Nd, Gd, Pr) and BaLaIn0.9M0.1O4 (M = Sc, Y) doped perovskites based on barium lanthanum indate ». Transactions of the Kоla Science Centre of RAS. Series : Engineering Sciences 1, n^o 1/2023 (29 mars 2023) : 105–9. http://dx.doi.org/10.37614/2949-1215.2023.14.1.019.

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The paper discusses the features of proton transport in isovalently doped layered perovskites based on barium-lanthanum indate BaLaInO4. The effect of the nature and concentration of the dopant on the unit cell size, water absorption, and proton conductivity was estimated. It is shown that the doping of the cationic sublattices of the layered perovskite BaLaInO4 with Nd3+, Gd3+, Pr3+, In3+, Y3+ ions makes it possible to increase the proton conductivity up to ~ 2 orders of magnitude, and the complex oxides obtained by this method are promising from the point of view of their further study as a material for a proton-conducting solid oxide electrolyte fuel cell.

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Elshorbagy, Mahmoud H., Oscar Esteban, Alexander Cuadrado et Javier Alda. « Nanostructured Top Contact as an Alternative to Transparent Conductive Oxides in Tandem Perovskite/c-Si Solar Cells ». Applied Sciences 12, n^o 4 (11 février 2022) : 1854. http://dx.doi.org/10.3390/app12041854.

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In the competition of solar cell efficiency, besides top-performance multijunction cells, tandem cells based on perovskites are also breaking efficiency records to enter into the 30% range. Their design takes advantage of the rapid development of perovskite cells, and the good sharing of the available spectrum between the perovskite, absorbing at short wavelengths, and the c-Si or similar lower band gap material, working at longer wavelengths. In this paper, we present a novel tandem solar cell that combines crystalline silicon (c-Si) and perovskites cells. We analyzed the device with computational electromagnetism based on the finite element method. Our design arranges the perovskite solar cell as a multilayer 1D grating, which is terminated with a gold thin film (top metallic contact). This multilayer nanostructure is placed on top of the c-Si cell and a thin protective dielectric layer of aluminum nitride covers the whole device. The short-circuit current of the perovskite cell is maximized by maintaining the current-matching conditions with the output from the c-Si cell. This optimization considers the geometrical parameters of the grating: period and thickness of the active layer of the perovskite cell. We compared the simulated short-circuit current of this device to the planar tandem solar cell with indium tin oxide (top contact). The comparison shows a slight increment, around 3%, of our device’s performance. Moreover, it has the potential capability to circumvent postprocessing procedures used with transparent contact oxides, which can reduce the device’s final efficiency. Furthermore, our proposed design can take advantage of photolithographic and nanoimprint techniques, enabling large-scale production at a relatively low cost.

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Sakhnenko, V. P., et N. V. Ter-Oganessian. « Theory of order–disorder phase transitions of B-cations in AB′1/2 B′′1/2O3 perovskites ». Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials 74, n^o 3 (25 avril 2018) : 264–73. http://dx.doi.org/10.1107/s205252061800392x.

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Perovskite-like oxides AB′1/2 B′′1/2O3 with two different cations in the B-sublattice may experience cation order–disorder phase transitions. In many cases the degree of cation ordering can be varied by suitable synthesis conditions or subsequent sample treatment, which has a fundamental impact on the physical properties of such compounds. Therefore, understanding the mechanism of cation order–disorder phase transition and estimation of the phase transition temperature is of paramount importance for tuning of properties of such double perovskites. In this work, based on the earlier proposed cation–anion elastic bonds model, a theory of order–disorder phase transitions of B-cations in AB′1/2 B′′1/2O3 perovskites is presented, which allows reliable estimation of the phase transition temperatures and of the reduced lattice constants of such double perovskites.

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Thangadurai, Venkataraman. « (Invited) Mixed Conductors for Advanced Solid Oxide Fuel Cells ». ECS Meeting Abstracts MA2023-02, n^o 46 (22 décembre 2023) : 2211. http://dx.doi.org/10.1149/ma2023-02462211mtgabs.

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Developing innovative electrode materials with high electrocatalytic activity is essential to advance the commercial viability of solid oxide fuel cells (SOFCs). Perovskite-type metal oxides have shown great potential as electrocatalysts for the oxygen reduction reaction and fuel oxidation. Mixed ionic and electronic conducting (MIECs) perovskites are being explored as electrodes which have demonstrated excellent chemical stability and provide more electrochemically active surface area. Here, we discuss our strategies towards the rational design of compositions to develop cost-effective and high-performance electrode materials for intermediate-temperature solid oxide fuel cells. Particular attention is centred on cathode materials and the role of thermal compatibility, electrical conductivity, and chemical stability towards improving the electrochemical performance of the cathode materials has been discussed.

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Darwish, Esraa, Moufida Mansouri, Duygu Yilmaz et Henrik Leion. « Effect of Mn and Cu Substitution on the SrFeO3 Perovskite for Potential Thermochemical Energy Storage Applications ». Processes 9, n^o 10 (13 octobre 2021) : 1817. http://dx.doi.org/10.3390/pr9101817.

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Perovskites are well-known oxides for thermochemical energy storage applications (TCES) since they show a great potential for spontaneous O2 release due to their non-stoichiometry. Transition-metal-based perovskites are particularly promising candidates for TCES owing to their different oxidation states. It is important to test the thermal behavior of the perovskites for TCES applications; however, the amount of sample that can be used in thermal analyses is limited. The use of redox cycles in fluidized bed tests can offer a more realistic approach, since a larger amount of sample can be used to test the cyclic behavior of the perovskites. In this study, the oxygen release/consumption behavior of Mn- or Cu-substituted SrFeO3 (SrFe0.5M0.5O3; M: Mn or Cu) under redox cycling was investigated via thermal analysis and fluidized bed tests. The reaction enthalpies of the perovskites were also calculated via differential scanning calorimetry (DSC). Cu substitution in SrFeO3 increased the performance significantly for both cyclic stability and oxygen release/uptake capacity. Mn substitution also increased the cyclic stability; however, the presence of Mn as a substitute for Fe did not improve the oxygen release/uptake performance of the perovskite.

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Badreldin, Ahmed, Aya E. Abusrafa et Ahmed Abdel-Wahab. « Oxygen-deficient perovskites for oxygen evolution reaction in alkaline media : a review ». Emergent Materials 3, n^o 5 (21 septembre 2020) : 567–90. http://dx.doi.org/10.1007/s42247-020-00123-z.

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AbstractOxygen vacancies in complex metal oxides and specifically in perovskites are demonstrated to significantly enhance their electrocatalytic activities due to facilitating a degree of control in the material’s intrinsic properties. The reported enhancement in intrinsic OER activity of oxygen-deficient perovskites surfaces has inspired their fabrication via a myriad of schemes. Oxygen vacancies in perovskites are amongst the most favorable anionic or Schottky defects to be induced due to their low formation energies. This review discusses recent efforts for inducing oxygen vacancies in a multitude of perovskites, including facile and environmentally benign synthesis strategies, characterization techniques, and detailed insight into the intrinsic mechanistic modulation of perovskite electrocatalysts. Experimental, analytical, and computational techniques dedicated to the understanding of the improvement of OER activities upon oxygen vacancy induction are summarized in this work. The identification and utilization of intrinsic activity descriptors for the modulation of configurational structure, improvement in bulk charge transport, and favorable inflection of the electronic structure are also discussed. It is our foresight that the approaches, challenges, and prospects discussed herein will aid researchers in rationally designing highly active and stable perovskites that can outperform noble metal-based OER electrocatalysts.

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Kostopoulou, Athanasia, Konstantinos Brintakis, Nektarios K. Nasikas et Emmanuel Stratakis. « Perovskite nanocrystals for energy conversion and storage ». Nanophotonics 8, n^o 10 (19 juillet 2019) : 1607–40. http://dx.doi.org/10.1515/nanoph-2019-0119.

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AbstractThe high demand for energy consumption in everyday life, and fears of climate change are driving the scientific community to explore prospective materials for efficient energy conversion and storage. Perovskites, a prominent category of materials, including metal halides and perovskite oxides have a significant role as energy materials, and can effectively replace conventional materials. The simultaneous need for new energy materials together with the increased interest for making new devices, and exploring new physics, thrust the research to control the structuring of the perovskite materials at the nanoscale. Nanostructuring of the perovskites offers unique features such as a large surface area, extensive porous structures, controlled transport and charge-carrier mobility, strong absorption and photoluminescence, and confinement effects. These features together with the unique tunability in their composition, shape, and functionalities make perovskite nanocrystals efficient for energy-related applications such as photovoltaics, catalysts, thermoelectrics, batteries, supercapacitor and hydrogen storage systems. The synthesis procedures of perovskite nanostructures in different morphologies is summarized and the energy-related properties and applications are extensively discussed in this paper.

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Rossel, Christophe. « Perovskites : a class of materials with multiple functionalities and applications ». Europhysics News 49, n^o 3 (mai 2018) : 10–14. http://dx.doi.org/10.1051/epn/2018301.

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First discovered in 1839 by Gustav Rose and named after the Russian mineralogist L. A. Perovksi, the perovskites have been extensively studied. These materials have a wide range of properties and many potential applications. The discovery of high temperature superconductivity in layered copper oxides in the mid-eighties and of efficient photovoltaic properties in hybrid organic-inorganic perovskite solar cells less than 10 years ago, have boosted the research efforts on these materials as well as the number of yearly publications.

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Mojović, Zorica, Srđan Petrović et Ljiljana Rožić. « The role of ruthenium in perovskite-type mixed oxide in the electrochemical degradation of 4-nitrophenol ». Tehnika 75, n^o 6 (2020) : 695–99. http://dx.doi.org/10.5937/tehnika2006695m.

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In this paper new perovskite-based electrode materials for 4-nitrophenol detection were characterized. Mixed oxides of pereovskite type with general molecular formula La0.7Sr0.3Cr1-XRuX03 (X= 0; 0.05) were synthesized by ceramic procedure. The results of X-ray diffraction analysis showed that synthesized system has two-phase structure, including strontium chromate phase beside dominant perovskite phase. Carbon paste electrode was modified with synthsized perovskites in order to study their electrochemical activity. Electrode prepared innn such manner were used for oxido-reduction of 4-nitrophenol in acidic media. The addition of ruthenium to perovskite structure lead to increased electrochemical activity of this electrode for reduction of 4-nitrophenol.

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Zhao, Zhijun, Lena Rehder, Frank Steinbach et Armin Feldhoff. « High-Entropy Perovskites Pr1-xSrx(Cr,Mn,Fe,Co,Ni)O3-δ (x = 0–0.5) : Synthesis and Oxygen Permeation Properties ». Membranes 12, n^o 11 (9 novembre 2022) : 1123. http://dx.doi.org/10.3390/membranes12111123.

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High-entropy perovskite oxides have already been studied in various fields owing to their high-entropy-induced properties. Partial substitution of an element by a lower valence element usually improves the oxygen permeability of perovskite oxides, but high substitution amounts may lead to structural instability. In this work, pure high-entropy perovskites Pr1-xSrx(Cr,Mn,Fe,Co,Ni)O3-δ with high amounts Sr up to x = 0.5 were synthesized via a sol–gel method. Several characterization methods prove that the solubility of Sr increases with higher temperatures of the heating treatment. The ceramic with x = 0.5 shows a transition from semi-conductive to metallic behavior when the temperature reaches 873K. Its oxygen flux is comparable to the low-entropy counterpart La0.6Sr0.4Co0.5Fe0.5O3–δ. A stable run of ca. 46.2 h was documented for oxygen permeation under an air/CO2 gradient.

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Ohtomo, Akira, Suvankar Chakraverty, Hisanori Mashiko, Takayoshi Oshima et Masashi Kawasaki. « Spontaneous atomic ordering and magnetism in epitaxially stabilized double-perovskites ». MRS Proceedings 1454 (2012) : 3–13. http://dx.doi.org/10.1557/opl.2012.923.

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ABSTRACTWe report on the atomic ordering of B-site transition-metals and magnetic properties in double-perovskite oxides, La2CrFeO6 (LCFO) and La2VMnO6 (LVMO), which have never been reported to exist in ordered forms. These double-perovskite oxides are particularly interesting because of possible ferromagnetism (expected from the Kanamori-Goodenough rule for LCFO) and half-metallic antiferromagnetism (predicted for LVMO). Using pulsed-laser deposition technique with single solid-solution targets, we have prepared epitaxial films in ordered forms. Despite similar ionic characters of constituent transition-metals in each compound, the maximum B-site order attained was surprisingly high, ∼90% for LCFO and ∼80% for LVMO, suggesting a significant role of epitaxial stabilization in the spontaneous ordering process. Magnetization and valence state characterizations revealed that the magnetic ground state of both compounds was coincidently ferrimagnetic with saturation magnetization of ∼2μBper formula unit, unlike those predicted theoretically. In addition, they were found to be insulating with optical band-gaps of 1.6 eV and 0.9 eV for LCFO and LVMO, respectively. Our results present a wide opportunity to explore novel magnetic properties of binary transition-metal perovskites upon epitaxial stabilization of the ordered phase.

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Geguzina, G. A. « The complex oxides with octahedral structures : Existence areas and phase transitions ». Journal of Advanced Dielectrics 10, n^o 01n02 (février 2020) : 2060013. http://dx.doi.org/10.1142/s2010135x20600139.

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The experimental and calculated data on the existence of complex oxides in solid state with the octahedral structures of four families, namely perovskites, Bi-containing layered perovskite-like ones, tetragonal tungsten bronzes and pyrochlores, and about their phase transitions are systematized and summarized on the basis of the quasi-elastic or geometric models of these structures. It has been established that similar existence areas and similar correlations between the interatomic bond strains in their structures, on the one hand, and the temperatures of their ferroelectric or antiferroelectric phase transitions, on the other hand, are observed for all of them, despite the differences in the compositions and structures of these oxides, but taking into account their similar parameters.

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Yang, Gene, Wonsang Jung, Sung-Jin Ahn et Dongkyu Lee. « Controlling the Oxygen Electrocatalysis on Perovskite and Layered Oxide Thin Films for Solid Oxide Fuel Cell Cathodes ». Applied Sciences 9, n^o 5 (12 mars 2019) : 1030. http://dx.doi.org/10.3390/app9051030.

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Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO3 perovskites and Ruddlesden-Popper (RP) oxides (A2BO4) have been widely used as promising cathode materials owing to their attractive physicochemical properties. In particular, oxides in forms of thin films and heterostructures have enabled significant enhancement in the ORR activity. Therefore, we aim to give a comprehensive overview on the recent development of thin film cathodes of SOFCs. We discuss important advances in ABO3 and RP oxide thin film cathodes for SOFCs. Our attention is also paid to the influence of oxide heterostructure interfaces on the ORR activity of SOFC cathodes.

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Lach, Jakub, Kun Zheng, Anna Niemczyk, Agnieszka Brzoza-Kos et Ryszard Kluczowski. « Cu-Content La_1−XSr_xNi_1−YCu_yO_3−Δ Perovskites As Cobalt-Free Cathode Materials for High-Performance It-SOFCs ». ECS Meeting Abstracts MA2023-01, n^o 55 (28 août 2023) : 2698. http://dx.doi.org/10.1149/ma2023-01552698mtgabs.

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Solid Oxide Fuel Cells (SOFCs) are one of the most attractive energy conversion and storage devices, which can be applied for decentralized energy applications. However, the high operating temperature making SOFCs still unmarketable, which indicates that lowering the working temperature of SOFCs while still maintaining a high-power output is very crucial. For Intermediate-Temperature Solid Oxide Fuel Cells (IT-SOFCs), new cathode materials with high electrocatalytic activity and stability are necessary to provide a stable and high performance of cells. Perovskite-structured oxide (ABO3−δ) is one group of the most interesting material candidates for IT-SOFCs, presenting great potential in chemical composition modifications, yielding the design and gain of desired physicochemical and electrochemical properties [1]. The simple perovskite LaCuO3 is one of the well-studied Cu-content oxides with a high conductivity (106 S·cm−1), but it can be hardly obtained and suffers with stability issues in air [1, 2]. To stabilize the perovskite structure and to improve electrochemical properties of Cu-content oxides A-site and B-site modification strategy can be applied. It has been noted that Cu- and Ni-containing LaNi0.5Cu0.5O3−δ simple perovskite possesses low cathodic polarization of 0.056 Ω·cm2 at 800 °C, and a high power output of 870 mW·cm−2 at 900 °C [1, 3]. The generation of oxygen vacancies by strontium doping contributes to the increase of ionic conductivity component, and the Sr dopant can reduce the oxygen vacancy formation energy and increase the ionic conductivity of La1−xSrxMO3−δ (M = Fe, Mn) perovskites [1,4]. Therefore, in this work, Cu-content La1−xSrxNi1−yCuyO3−δ oxides with strontium doping at the A-site were evaluated as very promising Co-free cathode material candidates for IT-SOFCs. In this work, all La1−xSrxNi1−yCuyO3−δ compounds have been successfully obtained using soft chemistry. The room-temperature crystal structure of all oxides was assigned to the R-3c trigonal system. The substitution of La with Sr lowers the phase transition temperature from the R-3c space group to Pm-3m simple perovskite while increases the oxygen non-stoichiometry and the thermal expansion coefficient of studied materials. All investigated materials are chemically compatible with GDC-10, while unstable in contact with LSGM and 8YSZ. The manufactured anode-supported IT-SOFC with the La0.95Sr0.05Ni0.5Cu0.5O3−δ cathode presents an excellent power density of 445 mW·cm−2 at 650 °C in humidified H2. The results confirmed that La1−xSrxNi1−yCuyO3−δ perovskites can be potentially qualified as promising cathode candidates for IT-SOFCs, yielding promising electrochemical performance in the intermediate-temperature range [1]. References: [1] J. Lach, K. Zheng, R. Kluczowski, A. Niemczyk, H. Zhao, M. Chen, Materials, 15(24), 8737, (2022). [2] J. S. Zhou, L. G. Marshall, J. B. Goodenough, Phys. Rev. B, 89, 245138, (2014). [3] A. Niemczyk, K. Zheng, K. Cichy, K. Berent, K. Kuster, U. Starke, B. Poudel, B. Dabrowski, K. Swierczek, Int. J. Hydrog. Energy, 45, 29449–29464, (2020). [4] A. B. Muñoz-García, A. M. Ritzmann, M. Pavone, J. A. Keith, E. A. Carter, Acc. Chem. Res. 47, 3340–3348 (2014).

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Chen, Xiaoyun, Jun Xu, Yueshan Xu, Feng Luo et Yaping Du. « Rare earth double perovskites : a fertile soil in the field of perovskite oxides ». Inorganic Chemistry Frontiers 6, n^o 9 (2019) : 2226–38. http://dx.doi.org/10.1039/c9qi00512a.

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Merkle, Rotraut, Maximilian F. Hoedl, Giulia Raimondi, Reihaneh Zohourian et Joachim Maier. « Oxides with Mixed Protonic and Electronic Conductivity ». Annual Review of Materials Research 51, n^o 1 (26 juillet 2021) : 461–93. http://dx.doi.org/10.1146/annurev-matsci-091819-010219.

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Oxides with mixed protonic and p-type electronic conductivity (and typically containing also mobile oxygen vacancies) are important functional materials, e.g., for oxygen electrodes in protonic ceramic electrochemical cells or for permeation membranes. Owing to the presence of three carriers, their defect chemical behavior is complex. Deviations from ideal behavior (defect interactions) have to be taken into account, which are related to the partially covalent character of the transition metal–oxygen bonds. Compared to acceptor-doped Ba(Zr,Ce)O3− z electrolytes, perovskites with redox-active transition-metal cations typically show smaller degrees of hydration. Trends in the proton uptake of (Ba,Sr,La)(Fe,Co,Y,Zn)O3−δ perovskites are analyzed and correlated to structural features (local lattice distortions) and electronic properties (the position of oxygen states on an absolute energy scale). The proton mobility in such mixed-conducting perovskites is estimated. Specific aspects of the application of protonic and electronic mixed-conducting oxides in protonic ceramic electrochemical cells are discussed, and an overview of recent materials and device developments is given.

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Heifets, Eugene, Eugene A. Kotomin, Alexander A. Bagaturyants et Joachim Maier. « Thermodynamic stability of stoichiometric LaFeO3 and BiFeO3 : a hybrid DFT study ». Physical Chemistry Chemical Physics 19, n^o 5 (2017) : 3738–55. http://dx.doi.org/10.1039/c6cp07986e.

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Environmental conditions for the stability of LaFeO₃ and BiFeO₃ perovskites were assessed using the phase diagrams derived from the results of hybrid density functional calculations of the total energies of these perovskites, related binary oxides and the oxygen molecule.

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Long, Youwen. « High-pressure synthesis and physical properties of A-site ordered perovskites ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C755. http://dx.doi.org/10.1107/s2053273314092444.

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ABO3-type perovskite oxides exhibit a wide variety of interesting physical properties such as superconductivity, colossal magnetoresistance, multiferroic behavior etc. For a simple ABO3 perovskite, if three quarters of the A site is replaced by a transition metal A', then the so-called A-site ordered double perovskite with the chemical formula of AA'3B4O12 can form. Since both A' and B sites accommodate transition metal ions, in addition to conventional B-B interaction, the new A'-A' and/or A'-B interaction is possible to show up, giving rise to the presence of many novel physical properties. Here we will show our recent research work on the high-pressure synthesis of several A-site ordered perovskites as well as a series of interesting physical properties like temperature- and pressure-induced intermetallic charge transfer, negative thermal expansion, magnetoelectric coupling multiferroic and so on. [1-3]

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Awin, Labib A., Mahmoud A. El-Rais, Abdunnaser M Etorki et Moda M. Ezrgane. « Removal of Methyl Violet from Aqueous Solutions Using the A Site Doped Perovskite +-Oxides BaxSr3-xNbO5.5 (x=0, 1 and 2) ». Journal of New Developments in Chemistry 3, n^o 1 (9 octobre 2020) : 23–31. http://dx.doi.org/10.14302/issn.2377-2549.jndc-20-3486.

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Three members of the A- site doped Nb perovskites with general formula Sr3NbO5.5, BaSr2NbO5.5 and Ba2SrNbO5.5 were synthesised by solid-state methods and their removal efficiency of Methyl violet from aqueous solutions investigated. The X-ray diffraction measurements demonstrated that the three samples have a faced cubic perovskite-type structure in space group Fm m. The addition of Ba2+ into the A-site of Sr3NbO5.5 has influenced the cell volume, crystal size and density. Subsequently, the removal capacity was also impacted. The crystallite size of the oxides was determined to be less than 82 nm. The maximum removal capacities of Methyl violet are found to be 46.5, 13.1 and 8.0 mg/g using Ba2SrNbO5.5, BaSr2NbO5.5 and Sr3NbO5.5 respectively. The amounts of the dye adsorbed by the oxides have increased as the Ba2+ content increased. The removals of Methyl violet have positive relationship with pH, temperature and the mass of the oxides.

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Poudel, Ujjwal, Madhu Sudhan Bhusal, Manish Bhurtel, Atish Adhikari et Narayan Prasad Adhikari. « Machine Learning in Predicting Lattice Constant of Cubic Perovskite Oxides ». Journal of Nepal Physical Society 8, n^o 1 (13 décembre 2022) : 27–34. http://dx.doi.org/10.3126/jnphyssoc.v8i1.48282.

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A sample of 3,115 data of perovskite oxides in the form of ABO3 (A and B being the cations) was taken for this study of the application of machine learning in predicting the lattice constants (a determining factor in material design). The ANN, DT, RF, KNN, and SVM models were used to predict the lattice constants of perovskites because machine learning techniques have been phenomenal in uncovering crystal structures in the field of material research in recent years. These models used properties like ionic radii, formation energy, and band gap as input features. The R2 score was used to assess the regression model’s performance. The Random Forest Regression Model outperforms all other regression models regarding dataset and features.

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Allabergenova, Regina, Daria Вobkova, Elizaveta Borodina, Tatiana Kryuchkova, Ekaterina Markova, Tatiana Sheshko, Nikolai Lobanov et Alexander Cherednichenko. « Synthesis, сharacterization, and сatalytic properties of GdCoO3 for dry reforming of methane ». Journal of the Serbian Chemical Society, n^o 00 (2023) : 96. http://dx.doi.org/10.2298/jsc230517096a.

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Perovskite oxides (ABO3) due to their high thermal stability and the ability to control the physico-chemical properties are considered as an alternative to traditional catalysts containing noble and transition metals. Herein, the recent research breakthroughs of GdCoO3 catalysts in experimental studies are summarized in detail. First, the perovskite-type GdCoO3 complex oxides were obtained by co-precipitation method with the various precipitators and were characterized by X-Ray Diffraction (XRD), low temperature nitrogen adsorption and IR spectroscopy. Physical and chemical analysis showed that the choice of precipitant doesn?t significantly affect the phase composition of the perovskites. The catalytic performance of gadolinium cobaltites was discussed. It was found that the use of cobaltites obtained by co-precipitation leads to inhibition of the side reaction of the reverse steam reforming of carbon monoxide. Finally, investigation the used catalysts demonstrated the formation of Gd2O2CO3 and metallic cobalt, which indicates the nature of active centers: gadolinium is the center of CO adsorption, while hydrogen chemisorption occurs on cobalt-sites.

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