Calculations for the Dielectric Anomaly in SnCl_22H_2O

概要

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To further understanding of the large dielectric anomaly in layered SnCl_22H_2O (SCD) calculation are performed on a layered Ising model with strong ferroelectric interactions within the hydrogen bonded planes and weak antiferroelectric interactions between planes. Series expansions are performed for nearest neighbor interactions and a layered mean field approximation is developed in which only the weak interplanar interactions are replaced by a mean field. The layered mean field approximation is shown to agree very well with the series expansions provided one is not too close to the transition. Comparison with experiment on SCD leads to a small dipole moment interacting with external fields of the order of 0.12 Debye, which indicates very small displacements of the heavy atoms at the transition. The model reproduces the effective critical exponent γ=7/4 in the region in which it is measured. With the hypothesis that SCD is antiferroelectric, the calculations lead to the estimate that the ratio of the strength of the interplanar interactions to the intraplanar interactions is only 10^<-5> to 10^<-6>.
社団法人日本物理学会の論文
1976-11-15