论文部分内容阅读
利用Ｒａｍａｎ散射研究了ＢｉＢｒ＿（２－ｘ）Ｓａ＿ｘＣｕＯ＿ｙ（ｘ＝０，０．２，０．４）单晶样品的声子振动性质。实验结果表明，在ＢｉＢｒ＿（２－ｘ）Ｓａ＿ｘＣｕＯ＿ｙ体系的Ｒａｍａｎ谱中主要出现以下几个频率的特征振动模，即１９６，３００，４６０，６２５和６６０ｃｍ￣（－１）；而频率为１９６，３００，６２５，６６０ｃｍ￣（－１）的特征峰的强度随着Ｂａ掺杂量的增加而增加。在早期的工作中，我们曾经研究过Ｂａ的掺杂对Ｂｉ２２０１相的非公度调制结构的影响。本文在此基础上着重分析了２２０１相中的这种非公度调制结构与其声子振动模的关系，由此指出超结构调制的增强（即调制周期降低）严重地改变了各原子层的对称特性，从而使得各原子层的声子Ｒａｍａｎ活性发生明显变化。
The phonon vibrational properties of BiBr_ (2-x) Sa_xCuO_y (x = 0, 0.2, 0.4) single crystal samples were investigated by Raman scattering. The experimental results show that the Raman spectra of BiBr_ (2-x) Sa_xCuO_y system are mainly characterized by the following modes: 196, 300, 460, 625 and 660 cm -1; while the frequencies are 196, 300 , The intensity of the characteristic peak of 625,660 cm ~ (-1) increases with the increase of Ba doping amount. In earlier work, we have studied the effect of Ba doping on the inhomogeneous modulation structure of the Bi2201 phase. Based on this, this paper focuses on the analysis of the relationship between this non-public modulation structure and its phonon vibration mode in 2201 phase. It is pointed out that the enhancement of superstructure modulation (ie, the decrease of modulation period) seriously changes the symmetry of each atomic layer Characteristics, so that the phonon Raman activity of each atomic layer changes significantly.