The effect of titanium excess and deficiency on the microstructure and dielectric properties of lanthanum doped Ba0.55Sr0.45TiO3 with colossal permittivity

The temperature dependent dielectric properties of (Ba0.54875Sr0.44875La0.0025)Ti(1+x)O3 with both an excess and a deficiency of 0.25 mol.% TiO2 were investigated. The samples were prepared by the mixed oxide method and sintered in a conventional oven at temperatures ranging from 1400 °C to 1475 °C. The cubic perovskite structure was confirmed with XRD at room temperature. The sample with an excess of 0.25 mol.% Ti exhibited reduced grain growth while abnormal grain growth was observed for samples without Ti modification. Samples exhibited colossal permittivity for all modified compositions. With a 0.25 mol.% deficiency of Ti a permittivity over 65,000 and a tan δ under 0.05 were measured over a temperature range of −68 °C to 150 °C and a frequency range between 50 kHz and 1 MHz. This paper shows that by fine tuning the composition, materials with new, exciting and widely adjustable dielectric properties can be achieved.

Authors:
Nurmi Kari, Jantunen Heli, Juuti Jari

Publication type:
A1 Journal article – refereed

Place of publication:

Keywords:
BST, Colossal permittivity, Doping, Lanthanum

Published:

Full citation:
Kari Nurmi, Heli Jantunen, Jari Juuti, The effect of titanium excess and deficiency on the microstructure and dielectric properties of lanthanum doped Ba0.55Sr0.45TiO3 with colossal permittivity, Journal of the European Ceramic Society, Volume 39, Issue 4, 2019, Pages 1110-1115, ISSN 0955-2219, https://doi.org/10.1016/j.jeurceramsoc.2018.12.039

DOI:
https://doi.org/10.1016/j.jeurceramsoc.2018.12.039

Read the publication here:
http://urn.fi/urn:nbn:fi-fe201901303572