Li_(0.025)Na_(0.0975)NbO_3的低温热电性及其测量

LOW TEMPERATURE PYROELECTRIC PROPERTIES OF Li_(0.025) Na_(0.975) NbO_3 AND THEIR MEASUREMENT

在300K至20K的温废范围内,研究了Li_(0.025)Na_(0.975)NbO_3晶体的热电性。在降温和升温过程中,热电系数分别在180K附近和260K附近显示峰值。这表示晶体中发生了低温相变而且该相变有很大的热滞(约80K)。观测了热电电荷随时间的变化。在降温和升温过程中,热电响应分别在180K附近和260K附近随时间改变极性。这一现象被认为是相变过程中两相共存的结果。

Pyroelectric properties of Li_(0.025) Nb_(0.975) NbO_3 crystals have been investigated in the temperature range from, 300K to 20K. The pyroelectric coefficient shows a peak at about 180K on cooling and at about 260K on heating. This is indicative of a low temperature phase transition with a large thermal hysteresis (about 80K). The pyroelectric time response has been observed. It changes its polarity with time at about 180K on cooling and at about 260K on heating. This phenomenon is attributed to the coexistence of two phases in the process of phase transition.