INFRARED STUDIES ON SOME SUBSTITUTED COPPER CHROMITE SPINELS

Infrared studies on the spinel oxides Cu1-xMgxCr2O4, Cu1-xCdxCr2O4, Cu Cr2-xRhxO4 and CuCr2-xAlxO4 show the presence of three bands nu1, nu2 and nu3 in the studied frequency range. With the presence of more than one type of cation on either site of the spinel lattice, all three ba nds are broadened. Any change in the band position of nu1 is attribute d to the change in the degree of tetragonality, and its intensity is d ependent on the degree of inversion. Infrared spectra of the rhodite s pinels show much sharper bands than the chromite spinels due to the ab sence of trigonal distortion in these spinel oxides.