Porous Glass‐Ceramic in the CαO–TiO 2 –P 2 O 5 System

A porous glass‐ceramic in the CaO–TiO 2 —P 2 O 5 system has been prepared by crystallization and subsequent chemical leaching of the corresponding glass. By applying a two‐step heat treatment to 45CaO · 25TiO 2 · 30P 2 O 5 glasses containing a few mol% of Na 2 O, volume crystallization results in the formation of dense glass‐ceramics composed of CaTi 4 (PO 4 ) 6 and β‐Ca 3 (PO 4 ) 2 phases. By leaching the resultant glass ceramics with HCI, β‐Ca 3 (PO 4 ) 2 is selectively dissolved out, leaving a crystalline CaTi 4 (PO 4 ) 6 skeleton. The surface area and mean pore radius of the porous glass‐ceramics were approximately 40 m 2 /g and 13 nm, respectively.