【摘要】 对K₂ZnCl₄铁电晶体在无公度-公度转变的相变点附近的孤子行为进行了研究。发现在相变点附近杂质使介电函数明显偏离居里-外斯定律,并导致介电峰值的明显下降;同时还发现杂质对升温相变点T_c^b较之对降温相变点T_c^c有更大的影响,这与Rb₂ZnCl₄等晶体中的情况恰好相反。采用朗道自由能理论可较好地描述杂质在相变点附近对介电函数的影响。分析表明滞后效应主要决定于杂质的钉扎作用,但并不否定晶格的派尔斯畸变势的影响,特别是在较纯的样品中更是如此。更多还原

【Abstract】 The soliton behavior of K2ZnCl4 crystal near commensurate-incommensurate phase transition point is investigated by dielectric measurement. It is found that the dielectric curve deviate from Curie-Weiss law and the dielectric peak value decrease with the increasing of the impurities. The influence of impurities on phase transition point Tch in heating run is larger than phase transition point Tcc in cooling run. This phenomenon is contrary to the case of Rb2ZnCl4 crystal. The linear and nonlinear response of a multisoliton lattice is well described by a Landau-type theory. Analysis shows that the thermal hysteresis is mainly determined by the action of impurities, but this does not imply that the Peierls lattice pinning potential may not play any role in the thermal hysteresis.更多还原