Patent ID: 8850851

Claim:
A process for making a substantially crystalline material having a chemical composition consisting essentially of Y 2 O 3 .(P 2 O 5 ) x , where x is the molar ratio of P 2 O 5 to Y 2 O 3 in the composition of the crystalline material, and 0.30 ≦x≦1.20, the process comprising the following steps: (I) providing a YP-glass having a composition consisting essentially of Y 2 O 3 .(P 2 O 5 ) y and a softening temperature of Tsoft, where y is the molar ratio of P 2 O 5 to Y 2 O 3 in the YP-glass, and 1.6≦y≦9.0; (II) providing a Y-source material; (III) obtaining a mixture upon melting having a molar ratio of P 2 O 5 to Y 2 O 3 equal to x and comprising a plurality of particles of the YP-glass and a plurality of particles of the Y-sourcc material; and (IV) heating the mixture resulting from step (III) to a temperature T 1 higher than Tsoft, whereby a first ceramic is obtained.