A combination of modeling and experimental work has led to the identification of a crystal cut of PZN-4.5PT 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.
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