Processing of crack-free high density polycrystalline LiTaO3 ceramics
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This work has successfully achieved high density (99.9%) polycrystalline LiTaO3. The keys to the high density without cracking were the use of LiF-assisted densification to maintain fine grain size as well as the presence of secondary lithium aluminate phases as grain growth inhibitors. The average grain size of the hot pressed polycrystalline LiTaO3 is less than 5 μm, limiting residual stresses caused by the anisotropic thermal expansion. Dilatometry results clearly indicate liquid phase sintering via the added LiF sintering aid. Efficient liquid phase sintering allows densification during low temperature hot pressing. Electron microscopy confirmed the high-density microstructure. Rietveld analysis of neutron diffraction data revealed the presence of LiAlO2 and LiAl5O8 minority phases and negligible substitutional defect incorporation in LiTaO3.
KeywordsResidual Stress Liquid Phase Sinter LiTaO3 LiAlO2 Precision Impedance Analyzer
The authors would like to thank Robert Reinovsky, program manager of LANL ADX Office C3 Science Campaign, for the funding support. Los Alamos National Laboratory is operated by Los Alamos National Security LLC under DOE Contract DE-AC52-06NA25396. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
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