PIEZOELECTRIC PROPERTIES OF A HIGH CURIE TEMPERATURE Pb(In1/2Nb1/2)O3-PbTiO3 BINARY SYSTEM SINGLE CRYSTAL NEAR A MORPHOTROPIC PHASE BOUNDARY

High-quality piezoelectric (1-x)Pb(In1/2Nb1/2)O3-xPbTiO3 binary system single crystals near a morphotropic phase boundary were successfully grown by a conventional flux method using PbO-PbF2-B2O3 flux. The largest crystal had dimensions of about 20 mm x 10 mm x 5 mm. The permittivity shows a shoulder at the ferroelectric rhombohedral to tetragonal phase transition temperature, Tfr=100 C, and then has a max (35000 at 1 kHz) at the ferroelectric tetragonal to paraelectric cubic phase transition temperature, Tc=260 C. The electromechanical coupling coefficient in rectangular bar mode, k33'=78%, for phased array ultrasonic transducers was obtained by using the rhombohedral 0.72Pb(In1/2Nb1/2)O3-0.28PbTiO3 single crystal oriented along the [001] axis in the shape of a rectangular bar of 0.2 mm in width, 0.5 mm in thickness and 9 mm in length. The k33'=78% is the highest value reported so far among all the piezoelectric materials with a Tc > 250 C. 16 refs.