Lattice vibrations and dielectric functions of ferroelectric SrBi{sub 2-x}Nd{sub x}Nb{sub 2}O{sub 9} bismuth layer-structured ceramics determined by infrared reflectance spectra

• Published in: Materials research bulletin Vol. 45; no. 11
• Main Authors: Zhu, M., Sun, L., Li, W.W., Yu, W.L., Li, Y.W., Hu, Z.G., Chu, J.H.
• Format: Journal Article
• Language: English
• Published: United States 15.11.2010
• Subjects: ABSORPTION SPECTROSCOPY; CERAMICS; FERROELECTRIC MATERIALS; INFRARED SPECTRA; LATTICE VIBRATIONS; MATERIALS SCIENCE; OPTICAL PROPERTIES
• DOI: 10.1016/J.MATERRESBULL.2010.07.007
• ISSN: 0025-5408

Infrared optical properties of SrBi{sub 2-x}Nd{sub x}Nb{sub 2}O{sub 9} (SBNN) ceramics with different Nd compositions (from 0 to 0.2) have been investigated by near-normal incident reflectance technique. The experimental spectra in the wavenumbers range of 350-1500 cm{sup -1} were analyzed using the Lorentz oscillator model for five infrared-active phonon mode observed. It is found that the frequencies of the NbO{sub 6} tilting and symmetric stretching modes linearly decrease with the Nd composition due to the octahedra distortion. The high-frequency dielectric constant varies in the range from 4.55 {+-} 0.04 to 4.80 {+-} 0.04. Owing to the contribution from the stronger electronic transitions, the real part of dielectric function Re({epsilon}) is estimated to about 4.0 in the high-frequency transparent region.