UNIAXIAL COMPRESSION EXPERIMENTS ON LEAD ZIRCONATE TITANATE 95/5-2 Nb CERAMIC: EVIDENCE FOR AN ORIENTATION-DEPENDENT, "MAXIMUM COMPRESSIVE STRESS" CRITERION FOR ONSET OF THE FERROELECTRIC TO ANTIFERROLECTRIC POLYMORPHIC TRANSFORMATION

Under nonhydrostatic loading, the FR1 to Ao polymorphic transformation of unpoled lead zirconate titanate 95/5-2Nb (PNZT) ceramic began when the maximum compressive stress equalled the hydrostatic pressure at which the transformation otherwise occurred. This criterion seemed not to apply to poled ce...

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Bibliographic Details
Published in:Journal of materials research 2000-01, Vol.15 (3), p.689-703
Main Authors: Zeuch, D H, Montgomery, S T, Holcomb, D J
Format: Article
Language:English
Online Access:Get full text
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Summary:Under nonhydrostatic loading, the FR1 to Ao polymorphic transformation of unpoled lead zirconate titanate 95/5-2Nb (PNZT) ceramic began when the maximum compressive stress equalled the hydrostatic pressure at which the transformation otherwise occurred. This criterion seemed not to apply to poled ceramic. However, unpoled ceramic is isotropic whereas poled ceramic is not. Assuming that the transformation depends on both the stress magnitude and its orientation relative to PNZT's structure, these disparate results can be resolved. This modified hypothesis makes two predictions for transformation of unpoled ceramic under uniaxial compression: (i) it will begin when the compressive stress equals the hydrostatic pressure for transformation, and (ii) steadily increasing stress will be required to drive it to completion. Experimental results that confirm these predictions are presented. The new hypothesis quantifies the observed effect of shear stress on the mean stress for onset of the transformation of unpoled ceramic and explains previously reported kinetic effects. 23 refs.
ISSN:0884-2914