The exact connections of the effective thermal properties of ferroelectric crystals with domain configurations

Exact connections between the effective thermal expansion and pyroelectric coefficients and the effective elastic and piezoelectric coefficients have been established for trigonal, tetragonal, and hexagonal ferroelectric crystals with compatible domain configurations, taking advantage of compatible but not necessarily uniform internal field resulted from a hydrostatic stress and uniform temperature change. These exact connections reduce the number of independent material constants, and thus the number of necessary experimental measurements, and allow the determination of the effective thermal moduli of a ferroelectric crystal from its effective electroelastic moduli. Numerical results are also presented to demonstrate the application of such exact connections.