Ferroelectric properties of [110], [001] and [111] poled relaxor single crystals: measurements and modeling

A combination of modeling and experimental work has led to the identification of a crystal cut of PZN-4.5%PT with enhanced piezoelectric coefficients for bending mode applications (d(31) = 690 pC/N, d(32) = -1670 pC/N) and direct evidence of a rhombohedral-orthorhombic phase transformation under [110] electric field loading. A crystal variant model enables the calculation of the physical properties of the single crystals with an engineered domain state (the piezoelectric, elastic, and dielectric coefficients) from the properties of the single domain [111] poled rhombohedral phase. This work focuses on the piezoelectric coefficients. Not all of the [111] piezoelectric coefficients have been measured. The modeling approach is used to compute the missing coefficients, d(15) and d(16) of the [111] poled crystal from the [001] and [110] properties. Criteria for variant and phase evolution in the model reproduce the observed hysteresis loops, remanent strain and remanent polarization. (C) 2002 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.