Effect of redox conditions of glass melting on the structure and the properties of titanium-containing gahnite glass-ceramics

In order to develop glass -ceramics containing ions of variable valence in lower oxidation states, it is important to know how changing the redox conditions of glass melting affects structure and properties of glass -ceramics. The zinc aluminosilicate glass nucleated by TiO2 was melted with and without addition of As2O3 and heat -treated from 720 degrees to 1350 degrees C to obtain gahnite-based glass -ceramics. DSC, XRD analysis, Raman spectroscopy and TEM studies revealed that variation of glass melting redox conditions affects kinetics of liquid phase separation and rutile crystallization, composition and structure of gahnite and rutile, crystallization of the residual glass, and does not affect kinetics of gahnite crystallization, gahnite and rutile fractions and structure of glass -ceramics. In glass -ceramics prepared from glasses melted without As2O3, absorption in the visible and near-IR spectral ranges is due to octahedrally coordinated Ti3+ ions in gahnite nanocrystals. The study is important for development of rare -earth -free phosphors.