掺Pb的Bi-Sr-Ca-Cu-O超导体及非晶体的Raman光谱

本文研究了Bi2Sr2CaCu2O8单晶(Tc=85K)、Bi2-xPbxSr2Ca2Cu3Oy单相(Tc=107K)和Bi(Pb)-Sr-Ca-Cu-O非晶体室温下20-720cm-1的Raman光谱.通过谱图的比较,我们认为456-466、631-650cm-1是高Tc氧化物的特征谱,它们与Cu-O链及Cu-O面上的强电子-声子耦合有关;掺Pb导致Bi(Pb)-O双层之间氧的分布改变,增强了Bi(Pb)-O双层之间的耦合,从而有助于提高超导转变温度Tc.

STUDY OF RAMAN SPECTRA FROM Bi(Pb)-Sr-Ca-Cu-O

Since the discovery of high-Tc superconductivity in Bi-Sr-Ca-Cu-O system, a great deal of efforts has been made to study the structure and electronic properties of superconducting phases. The di cussion on Raman spectra of high-Tc superconductor aims to clarify the feature of phone structure and to gain information on physical properties of material. Much research work has been done on Raman spectra of Bi-Sr-Ca-Cu-O systeem while a little on Pb-doped Bi-Sr-Ca-Cu-O system.This paper discusses the similarities and differences of Raman spectra from (2212) single crystal (Tc=85K, sp1), Pb doped (2223) phase (Tc=107K, sp2) and Pb-doped Bi-Sr-Ca-Cu-O nonsuperconductor which is amorphous solid (sp3). The spectra involve in 20-720cm-1. Raman spectra were excited by an argon laser (λ=514.5nm) and detected by Model SPEX-140 Raman Spectrometer with a resolution of 4cm-1. AⅡ the experiments were carried out at room temperature.The lines of 169, 456-466 and 631-650cm-1 only occur in the spectra of sp1 and sp2. The spectrum of sp3 is quite different from those of sp1 and sp2 either in the location of lines or the structure of spectrum, which suggests the structure disparity. The most unambiguous character is that high intensity lines are always narrow, and they pile up on two broad weak backgrounds.