Formation Of Colloidal Phosphorus Particles In Bariumphosphate Glasses

Barium phosphate glasses 40Ba0.60 P205 mol% were prepared by melting mixtures of NH4H2PO4 and BaCO3. Coloured glasses were obtained after heat treatment at 520 deg C. The colour is caused by colloidal dispersions formed by phosphorus atoms that were reduced by hydrogen released from the decomposition of NH4H2PO4. Samples were stored at room temperature for one year and x-ray diffraction and differential thermal analyses were performed to determine structural change. Colloidal particles formed during the glass preparation process and are brought into contact with air when the glass monoliths are milled and participate in chemical reactions, finally forming the crystal phase Ba(H2PO4)2.