Abstract
FTIR transmittance spectra and EPR investigation of three series of glass in the system A(2)O-(MoO3)(2)-P2O5 (A = Li, No) have been studied. FTIR results were interpreted in terms of vibrations of (PO2)(-) and (PO3)(2-) terminal groups, (PO4)(3-) anion and P-O-P bridge. The spectra show that traces of P=O (inherent to vitreous P2O5) are present only in glasses with Mol Pless than or equal to0.50. A comparison of the glass spectra with those of the reported vitreous compositions MoO2(PO3)(2), (MoO2)(2)P2O7 and MoOPO4 and crystalline phases A(2)MoO(4) indicates that the structure of this glass consists of distorted modifications of the structural groups that occur in the crystalline phases. EPR spectra obtained for the glasses studied are characteristic of Mo5+ cations in a distorted octahedral environment. X-ray diffraction was performed oil heated glasses from 300 to 700degreesC The glass range containing Li2O and Na2O result in the recrystallisation of several crystalline phases in this temperature range. One of them is a new lithium phosphate (PMoLi) whereas NaMo2OPO4 can exist both in crystalline and glass forms.