Department of Physics, Hallym University, 39 Hallymdaehakgil, Chuncheon, Gangwondo 200-702, Republic of Korea.
J Phys Condens Matter. 2010 Jun 9;22(22):225904. doi: 10.1088/0953-8984/22/22/225904. Epub 2010 May 20.
A strong relaxation mode was observed in the gigahertz frequency window in the paraelectric phase of Ba₀.₈₀Ca₀.₂₀TiO₃ single crystals by using Brillouin light scattering. The appearance and growth of this relaxation mode were accompanied by substantial softening of the longitudinal acoustic mode as well as a remarkable increase in the hypersonic damping. Similar to BaTiO₃, the temperature dependence of the relaxation time of Ba₀.₈₀Ca₀.₂₀TiO₃ displayed a slowing-down behavior near the Curie temperature, indicating the order-disorder nature of the paraelectric-ferroelectric phase transition in this substance. The dynamics of precursor polar clusters observed in this work was discussed in relation with recent theoretical studies and found to be consistent with their predictions.
利用布里渊光散射，在 Ba₀.₈₀Ca₀.₂₀TiO₃ 单晶的顺电相的千兆赫兹频率窗口中观察到了一个强烈的弛豫模式。这种弛豫模式的出现和增长伴随着纵声学模式的显著软化以及超高阻尼的显著增加。与 BaTiO₃ 类似，Ba₀.₈₀Ca₀.₂₀TiO₃ 的弛豫时间的温度依赖性在居里温度附近表现出减速行为，表明该物质的顺电-铁电相转变具有有序-无序的性质。本文讨论了实验中观察到的前躯体极性团簇的动力学，与最近的理论研究结果一致。
