Pyroelectric properties of (1-x)Pb(Mg_1/3Nb_2/3)O₃-xPbTiO₃ and (1-x)Pb(Zn_1/3Nb_2/3)O₃-xPbTiO₃ single crystals measured using a dynamic method

The pyroelectric coefficients of 0.72Pb(Mg_1/3Nb_2/3)O₃-0.28PbTiO₃ (PMN-28PT), 0.67Pb(Mg_1/3Nb_2/3)O₃-0.33PbTiO₃ (PMN-33PT), and 0.92 Pb(Zn_1/3Nb_2/3)O₃-0.08PbTiO₃ (PZN-8PT) single crystals, oriented and poled along three different crystallographic directions, [001]_C, [011]_C, and [111]_C, have been measured using a dynamic method. The suffix C indicates reference to the prototypic cubic coordinate system. Large coefficients of up to 1070 μ C m^-2 K^-1 have been observed for the [111]_C oriented, rhombohedral PMN-28PT and PMN-33PT samples, where the measurement direction corresponds to the polar axis of the crystal. For each composition and orientation two different poling procedures are compared, a commonly used field cooling method and a low temperature poling protocol. It was found that in otherwise pseudoorthorhombic samples of PZN-8PT, a room temperature rhombohedral phase could be stabilized by application of a field along the [111]_C direction while heating from -70°C.