Medium-range order and physicochemical properties of (100 - x)(0.5PbO . 0.5P sub(2)O sub(5)) . xTeO sub(2) glasses in terms of the constant stoichiometry grouping concept

Glasses in the (100 - x)(0.5PbO . 0.5P sub(2)O sub(5)) . xTeO sub(2) section of the PbO-P sub(2)O sub(5)-TeO sub(2) system have been synthesized over the entire composition range for the first time and their properties (Raman spectra, refractive index n, density d, glass transition temperature T sub(g), and light scattering losses) have been investigated. It has been demonstrated that the Raman spectra can be represented as a superposition of constant spectral forms corresponding to constant stoichiometry groupings PbO . P sub(2)O sub(5), TeO sub(2) . 2PbO . 2P sub(2)O sub(5), TeO sub(2) . PbO . P sub(2)O sub(5), 2TeO sub(2) . PbO . P sub(2)O sub(5), and TeO sub(2). The existence of crystals of the corresponding stoichiometry has been predicted using the constant stoichiometry grouping concept. The diagram of the constant stoichiometry grouping contents (determined from the Raman spectra) in glasses of the system under investigation has made it possible to determine the partial properties of constant stoichiometry groupings, to calculate the dependences of the refractive index and density on the composition, and to refine the values of n and d for vitreous tellurium dioxide and lead metaphosphate. The practical importance of glasses in the system under consideration for the use in photonic devices has been discussed.