Pyroelectric properties of rhombohedral and tetragonal Pb(In _1/2Nb_1/2)-Pb(Mg_1/3Nb_2/3)-PbTiO ₃ crystals

Pyroelectric properties of rhombohedral and tetragonal single crystals Pb(In_1/2Nb_1/2)-Pb(Mg_1/3Nb_2/3)- PbTiO₃ (PIN-PMN-PT) were investigated, with temperature from -100 C to 100 C. At room temperature, the pyroelectric coefficient p and the figure of merit F_d of rhombohedral crystals are 7.81 10^-4 C/m ² K and 10.9 10^-5 Pa^-1/2, respectively, and 6.84 10^-4 C/m² K and 11.67 10^-5 Pa ^-1/2, respectively, for tetragonal crystals. Although the coefficient p and F_d at room temperature are similar for rhombohedral and tetragonal crystals, the F_d of tetragonal crystal is much more stable with respect to temperature, owing to its higher phase transition temperature and stable mono-domain state. From room temperature to 100 C, the F_d of rhombohedral crystal decreases from 10.74 10^-5 Pa^-1/2 to 5.3 10^-5 Pa^-1/2, while that of tetragonal crystals is nearly independent of temperature. Such investigation reveals that tetragonal PIN-PMN-PT crystal is more suitable for uncooled infrared detectors and imagers when compared with its rhombohedral counterpart.