Dielectric Dispersion in Ferroelectric N_2H_5Al(SO_4)_2・12H_2O

概要

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The complex dielectric constant of N_2H_5Al(SO_4)_2・12H_2O along the cubic [100] direction ε^* was measured in a frequency range between 10 kHz and 1 GHz. The critical slowing-down phenomenon of polarization was observed above the transition temperature 164.5 K (T_c). The experimental result was analyzed on the basis of the dielectric formula which represents the sum of two independent relaxators characterized by relaxation times τ_1 and τ_2. The static dielectric constant of one relaxator, ε_<1S>, obeys the Curie-Weiss law with the Curie constant C_1 =1.75×10^2 K and the paraelectric Curie temperature T_<01>=148 K, while that of the other, ε_<2S>, hardly depends on temperature. The relaxation time τ_1 can be well explained by the relation τ_1=τ_<01>. T/(T- T_<01>) with τ_<01>=(h/k_BT). exp (ΔF_1/k_BT), and the activation free energy was estimated to be Δ F_1=1.51×10^<-20> J just above T_c.
社団法人日本物理学会の論文
1994-04-15