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Theoretical Study of Antiferrodistortive Phase Transition in Strontium Titanate
Yu-ping Cai*, Dai-zhao Han, Ru-yun Ning
Department of Basic Courses, Ordnance Engineering College, Shijiazhuang 050003, China
Abstract:
At 105 K, strontium titanate is known to undergo an antiferrodistortive transition transform-ing from cubic to tetragonal structure as a result of the rotation of the oxygen octahedral around a cubic axe. Based on the Curie principle, the order parameter is determined to be a third-order complete symmetry polarization tensor. To take into account of quantum effects,the dielectric permittivity is measured from Landau free energy, and the Curie Weiss-type behavior is analyzed. From crystallization chemistry viewpoint, the dielectric behavior at low temperature is connected to small radius of Sr2+, which is much easier to move around the oxygen octahedral than Ba2+ in BaTiO3 or Pb2+ in PbTiO3.
Key words:  Spontaneous polarization, Dielectric permittivity, Free energy, Antiferrodis-tortive phase transition
FundProject:
Theoretical Study of Antiferrodistortive Phase Transition in Strontium Titanate
蔡玉平*, 韩代朝, 宁如云
军械工程学院基础部,石家庄050003
摘要:
SrTiO3在105 K发生反铁畸变从立方相进入四方相,这是由氧八面体绕一晶轴转动一微小角度引起的. 根据居里原理分析其序参量是一个三阶全对称的极张量. 从吉布斯自由能出发,得到了考虑量子效应的介电常数,并分析了低温时的居里-外斯行为. SrTiO3的低温介电行为与Sr2+的离子半径小有关,与BaTiO3和PbTiO3中的Ba2+和Pb2+相比,Sr2+更容易在氧八面体孔道中移动.
关键词:  自发极化,介电性,自由能,反铁畸变
DOI:10.1088/1674-0068/23/02/237-240
分类号: