Raman spectra and extended X-ray absorption fine structure characterization of La(2-x)/3NaxTiO3 and Nd(2-x)/3LixTiO3 microwave ceramics

Mei Yu Chen, Ching Yu Chiu, Chia Ta Chia, J. F. Lee, J. J. Bian

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Abstract

A-site deficient perovskite compounds, La(2-x)/3NaxTiO3 (0.02 ≤ x ≤ 0.5) and Nd(2-x)/3LixTiO3 (0.1 ≤ x ≤ 0.5) microwave ceramics, were investigated by Raman scattering. Nd(2-x)/3LixTiO3 (0.1 ≤ x ≤ 0.5) was also investigated by extended X-ray absorption fine structure (EXAFS) measurement. The Raman shifts of the E (239 cm-1) and A1 (322 cm-1) modes of La(2-x)/3NaxTiO3 were found to decrease with x. However, the E (254 cm-1) and A1 (338 cm-1) of Nd(2-x)/3LixTiO3 were found to blueshift with x, which was caused by Li substitution. The redshift of the A1 (471 cm-1) phonon of Nd(2-x)/3LixTiO3 (0.1 ≤ x ≤ 0.3) indicates that O-Ti-O bonding forces lessen with Li concentration, which is consistent with the EXAFS result that Ti-O bond lengths increase for 0.1 ≤ x ≤ 0.3. For x > 0.3, the EXAFS result shows that Ti-O bond lengths decrease. Moreover, Ti-O bond lengths show strong correlation with the microwave dielectric constants of Nd(2-x)/3LixTiO3.

Original languageEnglish
Pages (from-to)335-339
Number of pages5
JournalJournal of the European Ceramic Society
Volume30
Issue number2
DOIs
Publication statusPublished - 2010 Jan 1

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Keywords

  • Dielectric properties
  • Optical properties
  • Spectroscopy
  • X-ray methods

ASJC Scopus subject areas

  • Ceramics and Composites
  • Materials Chemistry

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