α-碘酸锂的电流弛豫和偏压场作用下表观介电常数弛豫行为

本工作较为详细地测定了静电场作用下α-碘酸锂的电流弛豫行为:在撤去c轴方向上的静电场后,从我们所用测量电流仪器的响应时间到某一t_k的区间内,放电电流服从(t/t₀)^-α的负幂次方律;而在t>t_k,其规律近似地为:(t/t₀)^{(-α′ln(t/t₀))}。相关的弛豫参数α,α′和t_k在有限的范围内,依赖于温度和施加电压的大小,也因样品不同而有差异。对将近十个样品进行了测试,结果表明,大多数晶体在尽可能小的电压下0.43≤α≤0.7,0.07<α′<0.09;上述的电流弛豫表达式与α-碘酸锂在偏压场作用下观察到的其它物理现象的弛豫行为,与在中子衍射加强和表观介电常数中的表现如出一辙;可以初步肯定各种现象的弛豫行为具有相同的物理根源。 关键词：

RELAXATION BEHAVIORS OF THE DEPOLARIZATION CURRENT AND THE APPARENT DIELECTRIC CONSTANT OF α-LiIO3 SINGLE CRYSTALS

A detailed experimental investigation of the current relaxation of α-LiIO₃ single crystals is reported in this article. It was found that after turn off of the dc field initially applied in the direction of C-axis, the decrease of current follows a negative power law (t/t₀)^-α from the beginning responding time of our apparatus to a certain time t_k, and after t_k the current decreases approximately as (t/t₀)^{(-α′ln(t/t₀))}. The parameters α,α′ and t_k depend on the temperature of the specimen and the magnitude of the applied field.Nearly ten specimens were measured, with a small dc field the results obtained on most crystals show that the parameters α and α′ change from specimen to specimen but have their values within the following range:0.43≤α≤0.7, 0.07≤α′≤ 0.09. We also found that both the relaxation behavior of the apparent dielectric constant and that of neutron diffraction observed on α-LiIO₃ conform to the same empirical expression as given above for the depolarization current except with different parameters. It may be concluded that these relaxation processes would be due to the same physical origin.