Patent ID: 8383537

Claim:
Apparatus for producing a glass or a glass-ceramic, said apparatus comprising a refractory body having a surface adapted to contact the glass or the glass-ceramic when the glass or the glass-ceramic is in a molten state, the refractory body comprising a phase which, on an oxide basis, consists of: (i) 2.5-13.0 mole percent P 2 O 5 (the first constituent); (ii) 2.5-13.0 mole percent Y 2 O 3 , Sc 2 O 3 , Er 2 O 3 , Lu 2 O 3 , Yb 2 O 3 , Tm 2 O 3 , Ho 2 O 3 , Dy 2 O 3 , Tb 2 O 3 , Gd 2 O 3 , or a combination thereof (the second constituent); and (iii) the remainder of the phase being ZrSiO 4 HfSiO 4 ThSiO 4 , or a combination thereof; wherein: (a) (i) and (ii) are in a dissolved state in (iii), (b) the refractory body has a volume of at least 200 cubic centimeters, and (c) the phase comprises at least 90 volume percent of the refractory body.