Microstructural Evolution of Bulk Composite Ferroelectrics and Its Effect on the Microwave Properties
J. Synowczynski, S. G. Hirsch, B. L. Gersten, Richard G. Geyer
A study was conducted to determine the influence of the processing conditions on the microstructural evolution and subsequent microwave properties of Ba0.55Sr0.45TiO3 (BST) MgO composites. The objective was to find the conditions necessary to maximize the permittivity while keeping the dielectric loss at a minimum. Experiments were designed to determine the effect of the processing at three different stages during the fabrication process: powder processing, green body densification, and sintering schedule. For the experiments, powders were processed using both conventional solid state calcinations (particle size1um) and wet chemical reactions (particle size 25-100 nm). These powders were then densified either colloidally (i.e., tape casting) or through uniaxial dry pressing. Geometric green density measurements revealed that the wet chemical powders compacted at a much lower green density than the calcined powders. These compacts were then sintered at three sintering temperatures (i.e, 1250oC 1350oC, and 1450oC) for 2 hours. SEM microscopy and BET analysis of the sintered compacts revealed the temperature onset for sintering as well as the grain growth kinetics. Archimedes density measurements determined that for wet chemically processed powders, the maximum density and minimum porosity were achieved at 1350oC sintering temperature, whereas the solid state calcined powders did not reach full density until 1450oC. The effect of these results on the microwave properties will be discussed in further detail.
, Hirsch, S.
, Gersten, B.
and Geyer, R.
Microstructural Evolution of Bulk Composite Ferroelectrics and Its Effect on the Microwave Properties, American Ceramic Society, Westerville, OH
(Accessed June 3, 2023)