PIEZOELECTRIC AND ACOUSTIC PROPERTIES OF POTASSIUM TITANYL PHOSPHATE (KTP) AND ITS ISOMORPHS

There is a need for new piezoelectric materials which possess both high electromechanical coupling coefficients and a weak temperature dependence for many frequency control applications. Potassium titanyl phosphate (KTP) has been shown to be a useful material for many electrooptical and nonlinear optical applications. The bulk elastic and piezoelectric properties of KTP and some of its family members such as RbTiOPO4 (RTP) and RbTiOAsO4 (RTA) have been determined. The piezoelectric, elastic, and dielectric matrix (P-E-D) of KTP has been completely characterized. Values for the temperature dependence of the expansion coefficients (alpha(ij)) and elastic constants (tau(c(ij)) have been obtained and the effects of variations in dielectric constant on coupling coefficient determined. The major diagonal elements of the piezoelectric and elastic matrices of RTP and RTA were measured as were the thermal expansion coefficient of all the KTP isomorphs. KTP, in the temperature range 25-degrees-C-80-degrees-C, is shown to have a combination of large coupling coefficients ( up to k(t) = 38% for hydrothermally grown KTP ) and medium temperature dependence coefficients of elastic constant ( as low as 40 ppm/degrees-C for tau(c33) for hydrothermally grown KTP ) that makes it attractive for many piezoelectric applications.