Chlorapatite Glass‐Ceramics

Apatite glass‐ceramics are attractive for medical and dental applications, and fluorapatite glass‐ceramics based on aluminosilicate glasses have been extensively studied. This study is the first study of chlorapatite glass‐ceramics based on calcium chloride‐containing Q 2 bioactive phosphosilicate glasses. The crystallization behavior of oxychloride glasses is examined and compared with mixed oxychloride/fluoride and oxyfluoride glasses. The glass transition temperature decreased for all three series with increasing halogen content. On increasing the halogen content, there was an increasing tendency of the glasses to crystallize. The halogen‐free glass surface crystallized to pseudowollastonite and an apatite. On incorporating a halide, the glasses exhibited largely bulk crystallization to a haloapatite. In the case of chloride, the glasses crystallized to chlorapatite. This is the first time to our knowledge that chlorapatite has been shown to crystallize from a glass. Chlorapatite is very attractive for medical applications because it converts to hydroxyapatite the mineral phase of tooth and bone on immersion in water.