SPECTROSCOPIC INVESTIGATIONS OF ULTRAPHOSPHATE GLASSES IN THE SYSTEM CoO-P₂O₅

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Ultraphosphate glasses in the system CoO-P₂O₅ were prepared from 0 to 18 mol% CoO (synthesis) starting from powdery P₄O₁₀ (p. a. Merck) and fresh prepared Co₂P₄O₁₂ in closed SiO₂ glass ampoules between 900° and 950°C for about 2 hours. Higher contents above 5 mol% CoO could not be investigated by optical spectroscopy because of their very high extinction. After cooling with about 10 K min^-1, the ampoules were stored under paraffin oil in a desiccator and handled with exclusion of “water”. Measurements of density, chemical composition, optical and infrared spectroscopy followed. The optical spectra only show Co²⁺ in 6 fold coordination. Co³⁺ was not found. The structure evolution seems to follow a binary distribution model which is non-linear: the (P₂O₅)_x specific substructure units decrease, where the CoP₄O₁₁ specific substructure units increase while the CoO content increases.