Large xenotime ceramic block and process for making the same

Abstract

A ceramic block consisting essentially of substantially homogeneous (Y 2 O 3 ) x .P 2 O 5 , where 0.95≦x≦1.05, having length LL, a width WW and a height HH, and a volume VV of at least 8×10 −3 m 3 essentially free of cracks throughout the volume, a density of at least 85% of the theoretical maximal density of Y 2 O 3 .P 2 O 5 under standard conditions, and a creep rate at 1250° C. and 6.89 MPa of CR, where CR≦8.0×10 −6 hour −1 , and method for making the same. The method utilizes a dry process where the starting YPO 4 -based ceramic material is synthesized by reacting anhydrous P 2 O 5 with dry Y 2 O 3 powder.

1 . A ceramic block consisting essentially of substantially homogeneous (Y 2 O 3 ) x .P 2 O 5 , where 0.95≦x≦1.05, having length LL, a width WW and a height HH, and a volume VV of at least 8×10 −3  m 3  essentially free of cracks throughout the volume, a density of at least 85% of the theoretical maximal density of Y 2 O 3 .P 2 O 5  under standard conditions, and a creep rate at 1250° C. and 6.89 MPa of CR, where CR≦8.0×10 −6  hour −1 . 
     
     
         2 . A ceramic block according to  claim 1  wherein 1.00≦x≦1.05. 
     
     
         3 . A ceramic block according to  claim 1 , wherein LL≧20 cm, WW≧20 cm, and HH≧20 cm. 
     
     
         4 . A ceramic block according to  claim 1 , wherein LL≧50 cm, WW≧30 cm, HH≧50 cm. 
     
     
         5 . A ceramic block according to  claim 1 , comprising calcium at a concentration by weight of [Ca], where [Ca]≦100 ppm. 
     
     
         6 . A ceramic block according to  claim 1 , comprising zirconium at a concentration by weight of [Zr], where [Zr]≦50 ppm. 
     
     
         7 . A ceramic block according to  claim 1 , comprising aluminum at a concentration by weight of [Al], where [Al]≦60 ppm. 
     
     
         8 . A ceramic block according to  claim 1  essentially free of alkali metal. 
     
     
         9 . A ceramic block according to  claim 1 , comprising barium at a concentration by weight of [Ba], where [Ba]≦100 ppm. 
     
     
         10 . A ceramic block according to  claim 1  essentially free of carbon. 
     
     
         11 - 21 . (canceled)