Uniaxial compression experiments on lead zirconate titanate 95/5-2Nb ceramic: Evidence for an orientation-dependent, ''maximum compressive stress'' criterion for onset of the ferroelectric to antiferroelectric polymorphic transformation
- Geomechanics Department, Sandia National Laboratories, P.O. Box 5800-0751, Albuquerque, New Mexico 87185-0751 (United States)
- Integrated Product Development Department, Sandia National Laboratories, P.O. Box 5800-0521, Albuquerque, New Mexico 87185-0521 (United States)
Recently we showed that, under nonhydrostatic loading, the F{sub R1}{yields}A{sub O} polymorphic transformation of unpoled lead zirconate titanate 95/5-2Nb (PNZT) ceramic began when the maximum compressive stress equaled the hydrostatic pressure at which the transformation otherwise occurred. More recently we showed that this criterion seemed not to apply to poled ceramic. However, unpoled ceramic is isotropic whereas poled ceramic is not. If we further assume 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. Here we present experimental results that confirm these predictions. We then revisit our earlier results for poled and unpoled PNZT. 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. (c) 2000 Materials Research Society.
- OSTI ID:
- 20216853
- Journal Information:
- Journal of Materials Research, Journal Name: Journal of Materials Research Journal Issue: 3 Vol. 15; ISSN JMREEE; ISSN 0884-2914
- Country of Publication:
- United States
- Language:
- English
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