Abstract: With the rapid development of the information technology, the requirements for surface acoustic wave devices are also increased. In order to find substrate materials with excellent surface acoustic wave performances, a detail theoretical analysis was conducted on the surface acoustic wave properties in 0.24PIN-0.47PMN-0.29PT single crystals along [001]_c and [011]_c at room temperature using the partial wave method. The relaxor ferroelectric single crystals xPb(In_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-(1-x-y)PbTiO₃ with compositions near the morphotropic phase boundary have comparably large piezoelectric and electromechanical properties and much higher Curie temperature. From the complete sets of elastic, piezoelectric and dielectric properties of [001]_c and [011]_c poled 0.24PIN-0.47PMN-0.29PT single crystals, the orientational dependence of surface acoustic wave phase velocities, electromechanical coupling coefficients and power flow angles was calculated by the Christoffel equation with semi-infinite boundary conditions. The results indicate that 0.24PIN-0.47PMN-0.29PT single crystals along [011]_c has better surface acoustic wave properties than the 0.24PIN-0.47PMN-0.29PT single crystals along [001]_c. It is very apparent that the surface acoustic wave electromechanical coupling coefficient for 0.24PIN-0.47PMN-0.29PT single crystal along [011]_c is dramatically higher compared to along [001]_c single crystal. Also, maximum power flow angle for 0.24PIN-0.47PMN-0.29PT single crystals along [011]_c is apparently bigger than 0.24PIN-0.47PMN-0.29PT single crystals along [001]_c. Therefore, the 0.24PIN-0.47PMN-0.29PT single crystal along [011]_c with excellent surface acoustic wave properties and temperature stability is very suitable in making surface acoustic wave devices.

Key words: relaxor ferroelectric single crystal, 0.24PIN-0.47PMN-0.29PT, surface acoustic wave, phase velocity, electromechanical coupling coefficient, power flow angle