Thermal behavior of sol-gel derived phosphate ceramics

A series of phosphosilicate and phosphotitanate ceramics with different com positions was prepared through sol-gel process. The phase evolution was stu died using X-ray diffractometry. P:Si gels remain amorphous up to the compo sitions 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 de grees C. Weight loss and phase transition of samples upon firing was invest igated using thermogravimetric analysis and differential thermal analysis. Linear percentage thermal expansion of P:Si and P:Ti crystal phase was obse rved and briefly discussed. (C) 2000 Elsevier Science Ltd. All rights reser ved.