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Title: Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure

Abstract

Formation and thermal stability of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 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 R3c symmetry (as that of the parent compound, BiFeO{sub 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{sub 3}-like R3c phase and a cubic (I23) sillenite-type phase based on γ-Bi{sub 2}O{sub 3}. Single-phase perovskite ceramics of the BiFe{sub 1-y}Sc{sub y}O{sub 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 R3c with the √2a{sub p}×√2a{sub p}×2√3a{sub p} superstructure (a{sub p} ~ 4 Å is the pseudocubic perovskite unit-cell parameter). The orthorhombic Pnma phase (√2a{sub p}×4a{sub p}×2√2a{sub p}) was obtained in the range of 0.30≤y≤0.60, while the monoclinic C2/c phase (√6a{sub p}×√2a{sub p}×√6a{sub 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{sub 1-y}Sc{sub y}O{sub 3} phasesmore » 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<0.50 and 0.50≤y≤0.70 start to decompose above 970, 920 and 870 K, respectively. - Graphical abstract: Formation of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 3} system when y≥0.15 requires application of pressure of several GPa. The phases formed under high pressure: R3c (0.20≤y≤0.25), Pnma (0.30≤y≤0.60) and C2/c (y≥0.70) are metastable. - Highlights: • Maximal Fe-to-Sc substitution rate in BiFeO{sub 3} at ambient pressure is about 15 at%. • R3c → Pnma → C2/c phase sequence in high-pressure prepared BiFe{sub 1-y}Sc{sub y}O{sub 3} ceramics. • The perovskite BiFe{sub 1-y}Sc{sub y}O{sub 3} phases formed under high pressure are metastable.« less

Authors:
 [1];  [2]; ; ;  [3]; ;  [4]
  1. Department of Materials and Ceramic Engineering and CICECO – Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro (Portugal)
  2. ISIS Facility, Rutherford Appleton Laboratory, Chilton, OX11 0QX Didcot (United Kingdom)
  3. Scientific-Practical Materials Research Centre of NAS of Belarus, P. Brovka Street, 19, 220072 Minsk (Belarus)
  4. Institute of Technical Acoustics of NAS of Belarus, Lyudnikov Avenue, 13, 210023 Vitebsk (Belarus)
Publication Date:
OSTI Identifier:
22658223
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 247; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; BISMUTH OXIDES; CERAMICS; CUBIC LATTICES; HEAT TREATMENTS; IRON OXIDES; MIXTURES; MONOCLINIC LATTICES; ORTHORHOMBIC LATTICES; OXIDATION; PEROVSKITE; PRESSURE RANGE MEGA PA 10-100; SCANDIUM COMPOUNDS; TRIGONAL LATTICES

Citation Formats

Salak, A.N., E-mail: salak@ua.pt, Khalyavin, D.D., E-mail: dmitry.khalyavin@stfc.ac.uk, Pushkarev, A.V., Radyush, Yu.V., Olekhnovich, N.M., Shilin, A.D., and Rubanik, V.V.. Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure. United States: N. p., 2017. Web. doi:10.1016/J.JSSC.2016.12.029.
Salak, A.N., E-mail: salak@ua.pt, Khalyavin, D.D., E-mail: dmitry.khalyavin@stfc.ac.uk, Pushkarev, A.V., Radyush, Yu.V., Olekhnovich, N.M., Shilin, A.D., & Rubanik, V.V.. Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure. United States. doi:10.1016/J.JSSC.2016.12.029.
Salak, A.N., E-mail: salak@ua.pt, Khalyavin, D.D., E-mail: dmitry.khalyavin@stfc.ac.uk, Pushkarev, A.V., Radyush, Yu.V., Olekhnovich, N.M., Shilin, A.D., and Rubanik, V.V.. Wed . "Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure". United States. doi:10.1016/J.JSSC.2016.12.029.
@article{osti_22658223,
title = {Phase formation in the (1-y)BiFeO{sub 3}-yBiScO{sub 3} system under ambient and high pressure},
author = {Salak, A.N., E-mail: salak@ua.pt and Khalyavin, D.D., E-mail: dmitry.khalyavin@stfc.ac.uk and Pushkarev, A.V. and Radyush, Yu.V. and Olekhnovich, N.M. and Shilin, A.D. and Rubanik, V.V.},
abstractNote = {Formation and thermal stability of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 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 R3c symmetry (as that of the parent compound, BiFeO{sub 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{sub 3}-like R3c phase and a cubic (I23) sillenite-type phase based on γ-Bi{sub 2}O{sub 3}. Single-phase perovskite ceramics of the BiFe{sub 1-y}Sc{sub y}O{sub 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 R3c with the √2a{sub p}×√2a{sub p}×2√3a{sub p} superstructure (a{sub p} ~ 4 Å is the pseudocubic perovskite unit-cell parameter). The orthorhombic Pnma phase (√2a{sub p}×4a{sub p}×2√2a{sub p}) was obtained in the range of 0.30≤y≤0.60, while the monoclinic C2/c phase (√6a{sub p}×√2a{sub p}×√6a{sub 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{sub 1-y}Sc{sub y}O{sub 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<0.50 and 0.50≤y≤0.70 start to decompose above 970, 920 and 870 K, respectively. - Graphical abstract: Formation of perovskite phases in the BiFe{sub 1-y}Sc{sub y}O{sub 3} system when y≥0.15 requires application of pressure of several GPa. The phases formed under high pressure: R3c (0.20≤y≤0.25), Pnma (0.30≤y≤0.60) and C2/c (y≥0.70) are metastable. - Highlights: • Maximal Fe-to-Sc substitution rate in BiFeO{sub 3} at ambient pressure is about 15 at%. • R3c → Pnma → C2/c phase sequence in high-pressure prepared BiFe{sub 1-y}Sc{sub y}O{sub 3} ceramics. • The perovskite BiFe{sub 1-y}Sc{sub y}O{sub 3} phases formed under high pressure are metastable.},
doi = {10.1016/J.JSSC.2016.12.029},
journal = {Journal of Solid State Chemistry},
number = ,
volume = 247,
place = {United States},
year = {Wed Mar 15 00:00:00 EDT 2017},
month = {Wed Mar 15 00:00:00 EDT 2017}
}
  • Recently, A 2B 3-type tetradymites have developed into a hot topic in physical and material research fields, where the A and B atoms represent V and VI group elements, respectively. In this study, in situ angle-dispersive X-ray diffraction measurements were performed on Bi 2Te 2Se, BiSbTeSe 2, and Sb 2Te 2Se tetradymites under high pressure. Bi 2Te 2Se transforms from a layered rhombohedral structure (phase I) into 7-fold monoclinic (phase II) and body-centered tetragonal (phase IV) structures at about 8.0 and 14.3 GPa, respectively, without an 8-fold monoclinic structure (phase III) similar to that in Bi 2Te 3. Thus, themore » compression behavior of Bi 2Te 2Se is the same as that of Bi 2Se 3, which could also be obtained from first-principles calculations and in situ high-pressure electrical resistance measurements. Under high pressure, BiSbTeSe 2 and Sb 2Te 2Se undergo similar structural phase transitions to Bi 2Te 2Se, which indicates that the compression process of tellurides can be modulated by doping Se in Te sites. According to these high-pressure investigations of A 2B 3-type tetradymites, the decrease of the B-site atomic radius shrinks the stable pressure range of phase III and expands that of phase II, whereas the decrease of the A-site atomic radius induces a different effect, i.e. expanding the stable pressure range of phase III and shrinking that of phase II. Lastly, the influence of the atomic radius on the compression process of tetradymites is closely related to the chemical composition and the atom arrangement in the quintuple layer.« less
  • Recently, A 2B 3-type tetradymites have developed into a hot topic in physical and material research fields, where the A and B atoms represent V and VI group elements, respectively. In this study, in situ angle-dispersive X-ray diffraction measurements were performed on Bi 2Te 2Se, BiSbTeSe 2, and Sb 2Te 2Se tetradymites under high pressure. Bi 2Te 2Se transforms from a layered rhombohedral structure (phase I) into 7-fold monoclinic (phase II) and body-centered tetragonal (phase IV) structures at about 8.0 and 14.3 GPa, respectively, without an 8-fold monoclinic structure (phase III) similar to that in Bi 2Te 3. Thus, themore » compression behavior of Bi 2Te 2Se is the same as that of Bi 2Se 3, which could also be obtained from first-principles calculations and in situ high-pressure electrical resistance measurements. Under high pressure, BiSbTeSe 2 and Sb 2Te 2Se undergo similar structural phase transitions to Bi 2Te 2Se, which indicates that the compression process of tellurides can be modulated by doping Se in Te sites. According to these high-pressure investigations of A 2B 3-type tetradymites, the decrease of the B-site atomic radius shrinks the stable pressure range of phase III and expands that of phase II, whereas the decrease of the A-site atomic radius induces a different effect, i.e. expanding the stable pressure range of phase III and shrinking that of phase II. Lastly, the influence of the atomic radius on the compression process of tetradymites is closely related to the chemical composition and the atom arrangement in the quintuple layer.« less
  • Three methods were used for the synthesis of LiAl{sub y}Ni{sub 1-y}O{sub 2} solid solutions with layered crystal structure: citrate and hydroxide precursor methods at atmospheric pressure and high-pressure synthesis in oxygen-rich atmosphere (3GPa). Structural characterization of the oxides was performed by powder XRD analysis and electron paramagnetic resonance (EPR) spectroscopy. Irrespective of the different preparation techniques used, it was found that LiAl{sub y}Ni{sub 1-y}O{sub 2} solid solutions can be formed in the limited concentration range of 0=<y=<0.5 and 0.75=<y=<1.0. The unit cell parameter a decreases linearly with the Al content whereas the unit cell parameter c increases sharper as comparedmore » to the linear interpolation of the c parameter calculated for the two end compositions LiNiO{sub 2} and LiAlO{sub 2}. In these compositions, aluminum substitutes for Ni in the NiO{sub 2}-layer, the mean Al{sub y}Ni{sub 1-y}-O bond length decreasing. The extent of the trigonal distortion of Al{sub y}Ni{sub 1-y}O{sub 6} and LiO{sub 6}-octahedra varies with the aluminum content and depends on the synthesis procedure used. The LiO{sub 6}-octahedra are more flexible to tolerate the increased trigonal distortion as compared to the Al{sub y}Ni{sub 1-y}O{sub 6}-octahedra. High-pressure synthesis favors the formation of oxides with a higher extent of trigonal distortion of both Al{sub y}Ni{sub 1-y}O{sub 6} and LiO{sub 6}-octahedra. From EPR measurements, it was shown that local cationic distribution in LiAl{sub y}Ni{sub 1-y}O{sub 2} depends on the synthesis temperature. At atmospheric pressure, higher synthesis temperatures promote the reaction of cation mixing between the layers.« less
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