Experimental Study of Antiferroelectric Copper Formate Tetrahydrate and Its deuterium Substitute

概要

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Antiferroelectric properties of Cu(HCOO)_24H_2O and Cu(HCOO)_24D_2O were investigated experimentally. Dielectric constant as a function of temperature shows a behavior of the first order transition with a large discon tinuity at the transition. The transition point is shifted from -37.7℃ for hydrogenous crystal to -27.7℃ by deuterium substitution. The Curie-Weiss constant for dielectric constant above the transition is 3.1×10^4℃ in both crvstals. Typical double hysteresis loop was observed in the antiferroelectric phase under a pulsive sinusoidal electric field. From the double loops at various temperatures, critical field to induce a forced transition and spontaneous polarization of sublattice as function of temperature were obtained. The critical field shows a linear dependence on temperature and is stays finite at the transition point. The spontaneous polarization is almost constant of 6μcoul/cm^2 and shows discontinuous vanishing at the transition pint. This value agrees well to the calculated value from the transition entropy.
社団法人日本物理学会の論文
1968-10-05