Dynamical mechanism of the ferroelectric phase transition ofSrTi18O3studied by light scattering
Dynamical mechanism of the ferroelectric phase transition ofSrTi18O3studied by light scattering
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光散射研究SrTi18O3铁电相变的动力学机制
DOI：
10.1103/physrevb.68.014109
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发表时间：
2003
影响因子：
3.7
通讯作者：
T. Yagi
中科院分区：
文献类型：
--
作者：
H. Hasebe;Y. Tsujimi;Ruiping Wang;M. Itoh;T. Yagi
在两块SrTi（18 Ox 16 O 1 - x）3单晶片（x = 0.86（STO 18 -86）和x=0.53（STO 18 -53））上进行了光散射实验。c 4 4纯横向声模和抗铁畸变Eg模在Tc以下分裂为两个模，对于STO 18 -86，Tc =27′1 K;对于STO 18 -53，Tc =20′2 K。这些分裂强烈暗示，晶体对称性变得低于四氢呋喃酮低于Tc，相变确实发生在Tc。此外，铁电Eu软模被发现高于Tc，但它的软化是不完全的。这一事实表明SrTi（18 Ox 16 O 1 - x）3的相变机制是位移型的（Eu模的不稳定性引起铁电相变），但不是理想的相变机制。发现在x>0.33的范围内，随着汇率x的减小，置换特征变得更强。
A light scattering experiment has been performed on two SrTi( 1 8 O x 16O 1 - x ) 3 single crystal plates with x = 0.86 (STO18-86) and x=0.53 (STO18-53). Each of the c 4 4 pure transverse acoustic mode and the antifer-rodistortive Eg mode splits into two modes below T c ; T c =27′1 K for STO18-86 and T c =20′2 K for STO18-53. These splits strongly imply that the crystal symmetry becomes lower than tetragonal one below T c , and that the phase transition really occurs at T c . Moreover, the ferroelectric E u soft mode is found above T c , but its softening is not complete. This fact indicates that the phase transition mechanism of SrTi( 1 8 O x 16O 1 - x ) 3 is of displacive type (the instability of the E u mode causes the ferroelectric phase transition), but is not the ideal one. The displacive character is found to become stronger with decreasing exchange rate x in the range x>0.33.