Some studies of the optical properties of molybdenum-phosphate glasses

A series of binary MoO₃-P₂O₅ and ternary MoO₃-In₂O₃-P₂O₅ glasses was prepared and their optical properties were investigated. The optical absorption edge of the glasses was measured for specimens in the form of thin blown films. It was found that the fundamental absorption edge of these glasses usually occurs in the ultraviolet region. The linear variation of ()^1/2 with where is the absorption coefficient and is the incident photon energy, is taken as evidence of non-direct interband transitions. The linear dependence of optical gap with molybdenum content indicates that the molybdenum content controls the absorption phenomena in this glassy system. The infrared spectra of all the glasses appeared to be almost the same, indicating that the infrared bands arise primarily from the vibrations of the phosphate and molybdate groups. The structure of molybdenum phosphate glasses is discussed in terms of the formation of mixed phosphate and MoO₄ tetrahedra.