Pyroelectricity and Spontaneous Polarization in LiNbO3

Measurements have been made concerning the magnitude of the pyroelectric coefficient dPs/dT in LiNbO3 over the temperature range from 25° to 450°C. The pyroelectric coefficient was found to be −4×10−9 C/cm2/°C at 25°C. The spontaneous polarization was determined to be a decreasing function of temperature in the crystals measured which were pulled from the melt. Over the temperature range measured Ps was found to decrease by 3.7 μC/cm2. From these pyroelectric measurements and preliminary data on the temperature dependence of the nonlinear optical coefficient d33 in LiNbO3, for d33 ∝ Ps, the magnitude of Ps at room temperature is estimated to be at least of the order of 50 μC/cm2.