Temperature Dependence of Infrared Spectra of (La1-xBax)2CuO4-y

Abstract

Temperature dependence of the infrared spectra of (La_1-x Ba _x )₂CuO_4-y (x=0, 0.02, 0.06, 0.10, 0.20) have been measured in the energy region between 400 and 800 cm^-1. For x=0 and 0.02, the crystal structure is orthorhombic at room temperature and becomes tetragonal (T _t phase) at elevated temperature. For x=0.06, 0.10 and 0.20, the crystal structure is tetragonal (T _x phase). It has been found that the infrared spectra are different for the T _t phase and the T _x phase. From the difference of the infrared spectra and the similarity of the X-ray diffraction patterns, the T _t phase is concluded to be of the K₂NiF₄ type and the T _x phase is expected to be of the Nd₂CuO₄ type.