Study the Raman Spectra and Dielectric Properties of Hexagonal BaTi_1-xGa_xO₃ Ceramics

Abstract

A series of polycrystalline Ga-doped Barium titanate (BaTi_1-xGa_xO₃) were synthesized for the studies on the dopant-concentration dependence of Raman spectra and dielectric properties. The Qx f value of Ga-doping samples increases up to about 20% of Ga concentration, but the dielectric constant (K-value) decreases while the A_1g phonon mode (636 cm⁻¹) experiences an increasing red-shift. The phonon mode becomes soft with Ga-ion increasing, and the FWHM of Raman peak increases with Ga-ion increasing until tetragonal structure appeared. The effective ionic weight, ionic radii and Coulomb interaction are important influences, which induce the chemical pressure and reduce the excess charge in Ti-site in the Ga-doping h-BaTiO₃ system. The relation between Raman mode shifter and K-value, and the correlation of the Qx f value and the FWHM of related phonon vibrations have been reported and examined.

Keywords:

• Solid state reaction method
• dielectric properties
• raman spectra
• BaTiO₃
• titanates

Acknowledgments

The author thanks for Prof. C.-T. Chia of department of physic, National Taiwan Normal University for his help in Raman spectra measurement and useful discussion. The author is also indebted to the Prof. Y.-C. Chen of department of physic, National Cheng Kung University for her kind supplying of dielectric properties measurement.