Phase formation in the (1- y )BiFeO 3 - y BiScO 3 system under ambient and high pressure
| Autor: | N. M. Olekhnovich, Andrei N. Salak, Dmitry D. Khalyavin, V. Rubanik, Aleksandr D. Shilin, Anatoli V. Pushkarev, Yu. V. Radyush |
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| Rok vydání: | 2017 |
| Předmět: |
chemistry.chemical_element
Nanotechnology 02 engineering and technology Thermal treatment Perovskite 01 natural sciences Inorganic Chemistry Phase (matter) 0103 physical sciences Materials Chemistry Scandium Physical and Theoretical Chemistry Sillenite Perovskite (structure) 010302 applied physics Chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics Metastable phase Electronic Optical and Magnetic Materials Crystallography Ceramics and Composites Orthorhombic crystal system High-pressure synthesis 0210 nano-technology Stoichiometry Monoclinic crystal system Ambient pressure |
| Zdroj: | Journal of Solid State Chemistry Repositório Científico de Acesso Aberto de Portugal Repositório Científico de Acesso Aberto de Portugal (RCAAP) instacron:RCAAP |
| ISSN: | 0022-4596 |
| Popis: | Formation and thermal stability of perovskite phases in the BiFe 1- y Sc y O 3 system (0≤ y ≤0.70) were studied. When the iron-to-scandium substitution rate does not exceed about 15 at%, the single-phase perovskite ceramics with the rhombohedral R 3 c symmetry (as that of the parent compound, BiFeO 3 ) can be prepared from the stoichiometric mixture of the respective oxides at ambient pressure. Thermal treatment of the oxide mixtures with a higher content of scandium results in formation of two main phases, namely a BiFeO 3 -like R 3 c phase and a cubic ( I 23) sillenite-type phase based on γ-Bi 2 O 3 . Single-phase perovskite ceramics of the BiFe 1- y Sc y O 3 composition were synthesized under high pressure from the thermally treated oxide mixtures. When y is between 0 and 0.25 the high-pressure prepared phase is the rhombohedral R 3 c with the √2 a p ×√2 a p ×2√3 a p superstructure ( a p ~ 4 A is the pseudocubic perovskite unit-cell parameter). The orthorhombic Pnma phase (√2 a p ×4 a p ×2√2 a p ) was obtained in the range of 0.30≤ y ≤0.60, while the monoclinic C 2/ c phase (√6 a p ×√2 a p ×√6 a p ) is formed when y =0.70. The normalized unit-cell volume drops at the crossover from the rhombohedral to the orthorhombic composition range. The perovskite BiFe 1- y Sc y O 3 phases prepared under high pressure are metastable regardless of their symmetry. At ambient pressure, the phases with the compositions in the ranges of 0.20≤ y ≤0.25, 0.30≤ y y ≤0.70 start to decompose above 970, 920 and 870 K, respectively. |
| Databáze: | OpenAIRE |
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