Characterisation And Dielectric Property Analysis  of A-site Doped LaTiO3-δ Perovskites Synthesised by Ball Milling Method

Nanotech Research Facility, PSG Institute of Advanced Studies, Coimbatore 641 004, India

Adv. Mater. Lett., 2015, 6 (5), pp 395-401

DOI: 10.5185/amlett.2015.5827

Publication Date (Web): May 05, 2015

Copyright © IAAM-VBRI Press

E-mail: anu@psgias.ac.in

Abstract

The present work highlights a series of perovskites La_0.8A_0.2TiO_3-δ, (where A= Ba, Ca, Sr), which includes a high dielectric constant, a low dielectric loss over a wide temperature, in a frequency range of 30 MHZ. Undoped and A-site doped LaTiO_3-δ (with Ba²⁺, Sr²⁺ and Ca²⁺) perovskites were synthesised by solid state reaction method (ball milling). The perovskite phase formation of the milled precursor powders under thermal treatments was investigated by thermogravimetry/differential scanning calorimetry (TG/DSC). Structural analysis of the phase pure sintered pellets revealed an orthorhombic crystal structure for all perovskites. Surface morphology of the sintered pellets exposed the presence of nanosized grains. The oxidation states of La³⁺ and Ti³⁺ ions have been confirmed using X-ray Photoelectron Spectroscopy (XPS). The dielectric spectral analysis reveals that dielectric properties of the perovskites depend on temperature and frequency. Among the dopants Sr is found to be the most effective in increasing the dielectric properties of LaTiO_3-δ. This makes it suitable as a high dielectric material for making capacitors operating at higher frequencies.

Keywords

Powders solid state reaction, electron microscopy, dielectric properties, perovskites.