Reaction kinetics, sintering characteristics, and ordering behavior of microwave dielectrics: Barium magnesium tantalate
Journal
Journal of Materials Research
Journal Volume
11
Journal Issue
5
Pages
1219-1227
Date Issued
1996
Author(s)
Tsai C.-C.
Abstract
The formation process of Ba(Mg1/3Ta2/3)O3 was confirmed to be a direct reaction between constituent compounds without the presence of intermediate compounds. Isothermal analysis of reaction kinetics indicated the controlling reaction to be a three-dimensional diffusion process. Based on the Ginstling-Brounshtein model, the activation energy of the formation process was estimated to be 257 kJ/mol. A new definition of the ordering parameter for Ba(Mg1/3Ta2/3)O3 was deduced to quantitatively evaluate the ordering degree. Raising sintering temperatures resulted in an increase in the ordering degree and bulk density of Ba(Mg1/3Ta2/3)O3. Reducing the barium content in Ba(Mg1/3Ta2/3))O3 substantially resulted in improved densification and enhanced ordering structure. On the other hand, an excess barium content in specimens hindered the progress of sintering, and also induced the disordering structure.
Type
journal article