关键词: 拉曼散射;晶体结构;空间群

Abstract: The magnetic and transport properties of the rare-earth cobalt oxides RCoO_3 are strongly dependent on the rare earth ion and their detailed structure.The function of rare earth ion in the two structures were studied through Raman diffraction spectra. The results show RCoO_3 compounds present the Pm～3m cubic structure for R=La, Ce, Pr, Nd ,while compounds with smaller ionic radii (R=Sm, Eu, Gd and Dy) can be obtained in the orthorhombic structure [space group Pnma (D_(2h)~(16)), Z=4]. According to the structural and Raman behavior, RCoO_3 compounds can be classified into three groups: one includes La, Ce, Pr, Nd, the other one includes Sm, Eu, Gd, Dy, and the third includes Tm, Yb , Lu , Er.

Key words: The magnetic and transport properties of the rare-earth cobalt oxides RCoO_3 are strongly dependent on the rare earth ion and their detailed structure.The function of rare earth ion in the two structures were studied through Raman diffraction spectra. The results show RCoO_3 compounds present the Pm～3m cubic structure for R=La, Ce, Pr, Nd ,while compounds with smaller ionic radii (R=Sm, Eu, Gd and Dy) can be obtained in the orthorhombic structure [space group Pnma (D_(2h)~(16)), Z=4]. According to the structural and Raman behavior, RCoO_3 compounds can be classified into three groups: one includes La, Ce, Pr, Nd, the other one includes Sm, Eu, Gd, Dy, and the third includes Tm, Yb , Lu , Er.