摘要
在群论分析的基础上,研究了620～640cm^(-1)红外光谱峰的峰型、峰频、峰半宽度及强度随淬火温度的变化规律.证实了在YBa_2Cu_3O_(7-δ)处于正交相时,该峰本质上是α轴Cu-O-Cu局域模B_(3u)和一维Cu-O准局域模B_(2u)迭加而成,处于四方相时,两模简并成一个模.并讨论了YBa_2Cu_3O_(7-δ)中载流子对入射红外辐射的屏蔽效应.
On the basis of group theory analysis, the variation of the shape, frequency shift, linewidth and intensity of 620～640cm^(-1) IR absorption peak (P1) in YB_(a2)Cu_3O7_(7-6)
system vs quenching temperature has been systematically studied. It is verified that this peak consists of two overlapped peaks as YBa_2Cu_3O_7-δ is of orthorhombic phase at δ<0.5; onc located at high frequency is coorresponding to the localized mode B_(?)u of Cu-O-Cu vibration centre between Ba layers on a axis, and the other one at low frequency is corresponding to the quasi-localized vibration mode B_(2u) of Cu-O bond induced by the oxygen-vacancy in one dimensional Cu-O chain on b axis. These two modes are identical to each other in the tetragonal phase. Meanwhile, it has been also found at orthorhombic-to-tetragonal (O-T) transition that the intensity of the p_1 peak, which should begin to reduce, still increases. This anomalous phonomenon is attributed to the weakening of the effect of carrier screening on infrared radiation.
出处
《红外研究》
CSCD
北大核心
1989年第4期241-246,共6页
基金
国家超导中心资助
