Thermal behavior of sol–gel derived phosphate ceramics

Abstract

A series of phosphosilicate and phosphotitanate ceramics with different compositions was prepared through sol–gel process. The phase evolution was studied using X-ray diffractometry. P:Si gels remain amorphous up to the compositions of P:Si=0.4:1 mole ratio, and begin to crystallize to Si5O(PO4)6 at higher phosphorus contents. The sintering property examined by push-rod dilatometer technique showed that P:Si gels can be densified at 400°C. Weight loss and phase transition of samples upon firing was investigated using thermogravimetric analysis and differential thermal analysis. Linear percentage thermal expansion of P:Si and P:Ti crystal phase was observed and briefly discussed.