Structural phase transitions of robust insulating Bi{sub 1-x}La{sub x}Fe{sub 1-y}Ti{sub y}O{sub 3} multiferroics
- Functional Materials Research Laboratory, Tongji University, Shanghai 200092 (China)
- Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan)
In contrast to leaky BiFeO{sub 3}, of which two structural phase transitions of cycloidal modulated antiferromagnetic-paramagnetic and ferroelectric-paraelectric are observed below 850 °C, chemical co-substitution to form Bi{sub 1−x}La{sub x}Fe{sub 1−y}Ti{sub y}O{sub 3} ternary solid solution makes these multiferroic ceramics become robust insulating low dielectric loss and exhibit rich structural phase transitions. Differential thermal analysis and temperature-dependent X-ray diffraction measurements probe four first-order structural phase transitions, e.g., T{sub H} = 305 °C, T{sub N} = 365 °C, T{sub C} = 810 °C, and T{sub S} = 830 °C observed in the Bi{sub 0.98}La{sub 0.02}Fe{sub 0.99}Ti{sub 0.01}O{sub 3} system, which are reasonably attributed to Brazovskii-type cycloidal modulated antiferromagnetic-helimagnetic (at T{sub H}) and helimagnetic-paramagnetic (at T{sub N}) magnetic phase transitions, ferroelectric-paraelectric (at T{sub C}) and rhombohedral-cubic (at T{sub S}) structural phase transitions, respectively. Magnetic phase transition temperatures change a little but ferroelectric and lattice structural phase transition temperatures decrease gradually with increasing co-substitution up to composition-induced rhombohedral-(pseudo-)cubic structural phase boundary. The first-order nature of magnetic phase transition and emergence of helimagnetic phase were attributed to Ti{sup 3+} d{sup 1} magnetic disorder distribution in the Fe{sup 3+} d{sup 5}-O-Fe{sup 3+} d{sup 5} chains, while the first-order nature becomes weak with increasing co-substitution, owing to decreased ferroelectric rhombohedral lattice distortion. An intermediate rhombohedral paraelectric phase is discovered intervening between ferroelectric rhombohedral and paraelectric cubic phase, of which the temperature range defined by difference between T{sub C} and T{sub S} increases with increasing co-substitution. It was found that T{sub C} and T{sub S} are able to be predicted quantitatively by reduced mass of unit cell. These findings enrich our understanding of ferroic phase transitions and advance designing novel high temperature multiferroic compounds.
- OSTI ID:
- 22271121
- Journal Information:
- Journal of Applied Physics, Vol. 115, Issue 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANTIFERROMAGNETISM
BISMUTH COMPOUNDS
CERAMICS
DIFFERENTIAL THERMAL ANALYSIS
FERRITES
FERROELECTRIC MATERIALS
IRON IONS
PARAMAGNETISM
PHASE TRANSFORMATIONS
RELAXATION LOSSES
SOLID SOLUTIONS
TEMPERATURE DEPENDENCE
TITANATES
TITANIUM IONS
TRANSITION TEMPERATURE
TRIGONAL LATTICES
X-RAY DIFFRACTION