Search results for "perovskite"
showing 10 items of 458 documents
First principles hybrid Hartree-Fock-DFT calculations of bulk and (001) surface F centers in oxide perovskites and alkaline-earth fluorides
2020
Valuable discussions with E. A. Kotomin are gratefully acknowledged. Research contribution of R. E. and A. I. P. has been performed within the framework of the EUROfusion Enabling Research project: ENR-MFE19.ISSP-UL-02 “Advanced experimental and theoretical analysis of defect evolution and structural disordering in optical and dielectric materials for fusion applications.” The views and opinions expressed herein do not necessarily reflect those of the European Commission.
The challenge in realizing an exchange coupled BiFeO3-double perovskite bilayer
2020
Abstract In this work we propose a device design for efficient voltage control of magnetism. The magnetization of a ferrimagnetic double perovskite may be manipulated by an exchange coupled layer of multiferroic BiFeO3. Bilayers of Barium doped BiFeO3 and ferrimagnetic double perovskite Sr2FeMoO6 have been prepared by pulsed laser deposition motivated by the possibility of strong interlayer exchange coupling. While single layers of each material show high quality we observe that in both stacking orders the first layer decomposes during the deposition of the second layer. The reason for the decomposition are strongly differing growth conditions for BiFeO3 and Sr2FeMoO6. This means that the g…
Ab initio calculations of structural, electronic and vibrational properties of BaTiO3 and SrTiO3 perovskite crystals with oxygen vacancies
2020
The first-principles (ab initio) computations of the structural, electronic, and phonon properties have been performed for cubic and low-temperature tetragonal phases of BaTiO3 and SrTiO3 perovskite crystals, both stoichiometric and non-stoichiometric (with neutral oxygen vacancies). Calculations were performed with the CRYSTAL17 computer code within the linear combination of atomic orbitals approximation, using the B1WC advanced hybrid exchange-correlation functional of the density-functional-theory (DFT) and the periodic supercell approach. Various possible spin states of the defective systems were considered by means of unrestricted (open shell) DFT calculations. It was demonstrated that…
Continuous hydrothermal synthesis in supercritical conditions as a novel process for the elaboration of Y-doped BaZrO3
2021
Abstract The present work describes a novel process for the elaboration of a ceramic material. Y-doped barium zirconate, an electrolyte material for Protonic Ceramic Fuel cell, was synthesized by a continuous hydrothermal process in supercritical conditions (410 °C/30.0 MPa) using nitrate precursors and NaOH reactants. The use of supercritical water allowed the formation of particles of about 50 nm in diameter with a narrow size distribution. X-Ray Diffraction examination revealed that a major perovskite phase with few BaCO3 and YO(OH) impurities was obtained. BaCO3 is assumed to form due to faster kinetics than Y-doped BaZrO3 resulting in a Ba-deficient perovskite phase. The Ba-deficiency …
Epitaxial growth of perovskite oxide films facilitated by oxygen vacancies
2021
The authors would like to thank P. Yudin for valuable discussions, N. Nepomniashchaia for VASE studies, and S. Cichon for XPS analysis. The authors acknowledge support from the Czech Science Foundation (Grant No. 19-09671S), the European Structural and Investment Funds and the Ministry of Education, Youth and Sports of the Czech Republic through Programme ‘‘Research, Development and Education’’ (Project No. SOLID21 CZ.02.1.01/0.0/0.0/16-019/0000760), and ERA NET project Sun2Chem (E. K. and L. R.). Calculations have been done on the LASC Cluster in the ISSP UL.
Lower mantle hydrogen partitioning between periclase and perovskite : a quantum chemical modelling
2016
Abstract Partitioning of hydrogen (often referred to as H2O) between periclase (pe) and perovskite (pvk) at lower mantle conditions (24–80 GPa) was investigated using quantum mechanics, equilibrium reaction thermodynamics and by monitoring two H-incorporation models. One of these (MSWV) was based on replacements provided by Mg2+ ↔ 2H+ and Si4+ ↔ 4H+; while the other (MSWA) relied upon substitutions in 2Mg2+ ↔ Al3+ + H+ and Si4+ ↔ Al3+ + H+. H2O partitioning in these phases was considered in the light of homogeneous (Bulk Silicate Earth; pvk: 75%–pe:16% model contents) and heterogeneous (Layered Mantle; pvk:78%–pe:14% modal contents) mantle geochemical models, which were configured for lower…
La1−xSrxCo1−yFeyO3− perovskites: Preparation, Characterization and Solar Photocatalytic Activity in gas-solid regime
2014
Solid-state mechanochemical synthesis of multinary metal halide semiconductors for optoelectronics: From powder to thin film
2020
En la última década, las perovskitas de haluro de plomo, así como otros haluros de metales múltiples, incluidas las alternativas sin plomo, han demostrado ser materiales prometedores para su uso en optoelectrónica. Por lo tanto, se buscan activamente nuevas formas de producir semiconductores de alta pureza a gran escala. Por tanto, el objetivo principal de esta tesis doctoral es el desarrollo de perovskitas y semiconductores relacionados utilizando métodos sin disolventes. Además, con la perspectiva del uso de dichos materiales en optoelectrónica a escala industrial, el foco está puesto en trabajar con materiales benignos para el desarrollo de alternativas a las perovskitas tóxicas. La sínt…
Hybrid perovskites for light-emitting and photovoltaic devices
2017
El objetivo de esta tesis es el desarrollo de métodos y materiales apropiados para la preparación de capas delgadas de perovskitas híbridas, y su implementación en dispositivos optoelectrónicos. Se dedicará particular atención a las relaciones entre la naturaleza del material, el método de deposición y las propiedades optoelectrónicas. El trabajo está organizado como sigue: - Células solares de perovskitas preparadas por evaporación flash. Se desarrolla un simple método de evaporación por la preparación de células solares. - Dispositivos de perovskita con alta eficiencia fotovoltaica y electroluminiscente. En este capítulo se presentan dispositivos optoelectrónicos de perovskitas preparados…
DIELECTRIC AND PIEZOELECTRIC PROPERTIES OF 0.8Na0.5 Bi0.5 TiO3-0.2BaTiO3 MODIFIED WITH SODIUM NIOBATE
2022
This work was supported by the Research Council of Lithuania (Project S-LLT-20-4). This work has been supported by Mutual Funds Taiwan–Latvia– Lithuania Cooperation Project Application LV-LT-TW/2020/10.