VIBRATIONAL-SPECTRA OF 2 PHASES OF COPPER PYROVANADATE AND SOME SOLID-SOLUTIONS OF COPPER AND MAGNESIUM PYROVANADATE

Infrared and Raman spectra of both the alpha- and beta-phases of Cu2V2O7 are presented. Of the 13A' + 8 A'' vibrational modes of V2O74- all six of the ones predicted to be terminal stretching modes can be distinguished for both phases in the Raman. Both the symmetric and asymmetric bridge stretching modes are observed for alpha-Cu2V2O7. The Raman spectra of the solid solution series Cu2-xMgxV2O7 (x = 0.5; 0.67) are similar to that of beta-Cu2V2O7. The influence of magnesium substitution in the copper pyrovanadate lattice can be observed from the shift of vibrational bands.