Low temperature structural variations of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} single crystal: Evidences from optical ellipsometry and Raman scattering

Journal Article · Sun Jun 14 04:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4922424· OSTI ID:22412920

Huang, T.; Guo, S.; Xu, L. P.; Chu, J. H. ^[1]; Chen, C.; Luo, H. S. ^[2]

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1. Key Laboratory of Polar Materials and Devices, Ministry of Education, Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)
2. Key Laboratory of Inorganic Functional Materials and Devices, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800 (China)

Optical properties and structural variations of Na{sub 0.5}Bi{sub 0.5}TiO{sub 3}-7%BaTiO{sub 3} (NBT-7%BT) single crystal have been studied by temperature-dependent optical ellipsometry and Raman spectroscopy from 4.2 to 300 K. The second derivative of the complex dielectric functions reveals two interband transitions (E{sub cp1} and E{sub cp2}) located at about 3.49 and 4.25 eV, respectively. Depending on the temperature evolution of electronic transitions, structural variations appear near 60, 150, and 240 K, respectively. These anomalies are also well illustrated from the low-frequency phonon modes involving vibrations of Bi. The low-temperature structural variations of NBT-7%BT crystal can be associated with instability of the crystalline lattice driven by off-centered Bi ions, followed by the variations of polarizability of the unit cells.

• OSTI ID: 22412920
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 22 Vol. 117; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
BISMUTH IONS
CRYSTAL LATTICES
DIELECTRIC MATERIALS
ELLIPSOMETRY
ENERGY-LEVEL TRANSITIONS
MONOCRYSTALS
OPTICAL PROPERTIES
PERMITTIVITY
PHONONS
POLARIZABILITY
RAMAN SPECTROSCOPY
SODIUM COMPOUNDS
TEMPERATURE DEPENDENCE
TITANATES