LOW-TEMPERATURE SYNTHESIS, STRUCTURE AND BIOACTIVITY OF XCAO-CENTER-DOT(1-X)SIO2 GLASSES

Glasses of composition expressed by the following general formula xCaO (1-x)SiO2 (0.30 less than or equal to x less than or equal to 0.50) ca n be prepared by means of the sol-gel route starting from tetramethylo rthosilicate and calcium nitrate tetrahydrate They are all difficult t o prepare by means of the traditional technique of quenching the melt, because of the high liquidus temperature, T-1, that in the case of x= 0.3 glass is T-1=1650 degrees C. The DTA apparatus appears a valuable tool for defining the procedure necessary to obtain the glass through the sol-gel route. The glass x=0.3 is bioactive. The experimental resu lts suggest that the gel structures, such as obtained at room temperat ure, are very similar; only at high temperature do the reactions of hy drolysis and polycondensation go to completion and the structural unit s characteristic of each glass are obtained.