Crystallization and sintering behaviors of the polyphosphate glass doped with Zn and Mn

The crystallization and sintering behaviors of polyphosphate glass doped with trace elements Zn and Mn were examined. The heating experiments on bulk and powder glass samples were performed. The parent glass revealed low crystallization ability and the glass crystallization carried out under simultaneous acting of the surface and volume mechanisms. The bulk glass sample isothermally heated at T c = 500 °C commences to crystallize after 12 h, and KPO 3 and Ca 2 KP 3 O 10 crystalline phases appeared. The dendritic morphology of the crystals growing on sample surface was determined. The DTA and HSM results showed that the sintering and crystallization processes are independent. Phosphate glass-ceramics containing KPO 3 , K 2 Mg(PO 3 ) 4 , Ca(PO 3 ) 2 and KCa(PO 3 ) 3 crystalline phases has been prepared by sintering of the glass powder compacts at T c = 500 °C for t = 12 h. A plate-like morphology of crystals which grow on glass grains surface was observed. The activation energies of crystal growth, E a,k = (246.6 ± 19.74) kJ mol −1 (Kissinger) and E a,oz = (258.80 ± 19.70) kJ mol −1 (Ozawa), were calculated.