SOL-GEL SYNTHESIS OF PHOSPHATE CERAMIC COMPOSITES .1.

Monolithic gels of phosphate ceramics were synthesized using PO(OH)(3- x)(OR)(x) and alkoxides of silicon and titanium. The PO(OH)(3-x)(OR)(x ) species were synthesized from the reaction of P2O5 and ethanol or n- butanol, and the products consisted of approximately equal molar amoun ts of mono- and dialkyl phosphate. The phosphate gels containing titan ium lost less phosphorus than from the gels of silicon/phosphorus upon firing of gels in air. At phosphorus contents above 60 mole %, the ge ls were completely crystallized upon firing at temperatures above 700 degrees C, while the gels containing zinc and alkali metals remained a morphous after firing at 850 degrees C. Solid state nuclear magnetic r esonance spectroscopy showed that all of the silicon is hexacoordinate d in the phosphate gels containing silicon and titanium upon firing at temperatures above 520 degrees C