SrTiO3铁电体反铁畸变序参量的研究

钛酸锶(SrTiO3)的反铁畸变是氧八面体绕001]轴转过一微小角度θ引起的,由于前人对相变中晶体学原胞的选取不合适,所以不能正确说明晶体结构对称性的变化.本文提出一种晶体学原胞的选取方法,能很好地反映相变前后对称性的变化.由居里原理,分析其序参量是一个三阶全对称的极张量,并给出具体的数学形式.

Study on Order Parameter of Strontium Titanate during Antiferrodistortive Phase Transition

The antiferrodistortive phase transition in strontium titanate is driven by the rotation of the oxygen octahedral around 001] cubic axes. In the most previous papers, it is unsuitable for selecting the unit cell of strontium titanate, which cannot reflect the change of the crystal structure symmetry. Here, a new type of unit cell is given, which can reflect the symmetry changes perfectly during phase transition. According to the Curie principle, a third-order complete symmetry polarization tensor is put forward as the order parameter of antiferrodistortive phase transition.