title: The effect of inversion of matrix and inclusions composition in liquation phospho-silicate glasses.
abstract: Silico-phosphate glasses of XCaPO(4)-SiO(2) and XCaPO(4)-AlPO(4)-SiO(2) (X=Na(+) and/or K(+)) system have been the subject of the presented investigations. Glasses belonging to those systems are characterized by a liquation phenomenon-spherical amorphous inclusions dispersed in an amorphous matrix. Thorough EDX investigations have shown that introduction of aluminum ions into the structure of phospho-silicate glasses results in inversion of matrix and inclusions composition, when XCaPO(4) exceeds 25-35% mol. Such a substantial influence of aluminum ions on phospho-silicate glasses texture as well as matrix and inclusions composition (inversion) must be a result of structural changes. (27)Al MAS NMR research stated that aluminum ions in structures of XCaPO(4)-AlPO(4)-SiO(2) phospho-silicate glasses always acts as a glass-forming ion-i.e. aluminum always occupies fourfold coordinated sites. (23)Na and (31)P MAS NMR research has shown that the inversion of matrix and inclusions composition, brought about by introduction of aluminum ions into the structure of phospho-silicate glasses, is an outcome of a change in phosphorous and alkaline ions coordination.
authors.affiliation: AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Al. Mickiewicza 30, 30-059 Kraków, Poland. msitarz@agh.edu.pl
authors.forename: M
authors.initials: M
authors.lastname: Sitarz
mesh_terms: D005898:Glass / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010710:Phosphates / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry*
chemical_list: D010710:Phosphates; D017640:Silicates