The orientation-dependent electromechanical properties were calculated for tetragonal Pb(In1/2Nb1/2)O3-Pb(Mg 1/3Nb2/3)O3- PbTiO3 (PIN-PMN-PT) crystals based on single-domain data. The maximum electromechanical coupling was found to lie along the polar direction , whereas the maximum piezoelectric coefficient was found to occur along . Subsequently, the piezoelectric properties of  poled tetragonal PIN-PMN-PT crystals, with an engineered domain configuration ("2T"), were studied using resonance impedance measurement and strain versus electric field (S-E) behavior, where the piezoelectric coefficient d33 and coupling k33 of  poled crystals were found to be on the order of 1000 pC/N and 0.75, respectively. The high d33 of  poled crystals was associated with the high shear coefficient d15 (���2300 pC/N) in single domain state. Finally, the piezoelectric and electromechanical properties of  domain engineered tetragonal PIN-PMN-PT crystals were investigated as a function of temperature. In contrast to  single-domain PIN-PMN-PT crystals, the piezoelectric coefficient d33 and coupling k33 of  poled crystals were found to decrease with increasing temperature. �� 2010 The American Ceramic Society.