Kinetics of formation of lead zirconate titanate
The solid state reactions occurring in PbO--TiO/sub 2/--ZrO/sub 2/ system were investigated using constant heating rate method. The temperature range involved was from room temperature up to 1000/sup 0/C, the range normally associated with the calcining step in the processing of PZT. Experimental techniques used included DTA, dilatometric expansion, and x-ray diffraction analysis. PbTiO/sub 3/ was found to form exothermally as an intermediate product between 450 and 600/sup 0/C. PbZrO/sub 3/ formation was observed to be endothermic and starting at 700/sup 0/C followed immediately by its interdiffusion with PbTiO/sub 3/. Both PZ and PT formations are accompanied by large volumetric changes and yield products of very fine particle size and high resultant reactivity. Hence the interdiffusion of PZ and PT is rapid to completely form PZT solid solution around 800/sup 0/C. Formation of PbZrO/sub 3/ as an intermediate product is supported by the results of DTA and dilatometric expansion studies. Approximate estimation of the kinetic parameters from the DTA data using Kissinger's method was attempted. The method was found to be not useful due to broad nature of the DTA peaks. Samples were observed to shrink rapidly after the expansions associated with the intermediate reactions. A model has been proposed to account for such behavior which also explains the high reactivity exhibited by the intermediate phases. Based on this analysis it should be possible to optimize the calcination process to obtain highly reactive fine sized powders in the PZT system. The method could be extended to other systems involving large volumetric changes in the course of solid state reactions.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7265661
- Report Number(s):
- LBL-5175
- Resource Relation:
- Other Information: Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
LEAD COMPOUNDS
CHEMICAL PREPARATION
TITANATES
ZIRCONATES
CALCINATION
DIFFERENTIAL THERMAL ANALYSIS
DIFFUSION
HIGH TEMPERATURE
MEDIUM TEMPERATURE
PARTICLE SIZE
REACTION KINETICS
VERY HIGH TEMPERATURE
CHEMICAL REACTIONS
DECOMPOSITION
KINETICS
OXYGEN COMPOUNDS
PYROLYSIS
SIZE
SYNTHESIS
THERMAL ANALYSIS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
360201* - Ceramics
Cermets
& Refractories- Preparation & Fabrication