The charge state of titanium ions in Pd‐doped Ti:CMAS glass and glass‐ceramics

Abstract We have investigated the role of charge state of Ti in the electronic properties and structure of electrically conductive CMAS ‐TiO 2 ‐Pd glass and glass‐ceramics by X‐ray photoelectron spectroscopy, electron paramagnetic resonance, positron annihilation lifetime spectroscopy, and fluorescence spectroscopy. These studies suggest the concentration of Ti 3+ ions was, at most, ~0.1 wt% in glass‐ceramics devitrified in the reducing atmosphere of forming gas; no other glass or glass‐ceramic samples exhibited measurable levels of Ti 3+ . The observed fluorescence at liquid nitrogen temperature in parent glasses and glass‐ceramics obtained in air is explained by UV ‐induced charge‐transfer processes involving Ti 4+ ions and oxygen surroundings. The X‐ray photoelectron spectroscopy data are correlated with rutile, anorthite, diopside, and titanite crystalline phases identified in Pd‐free and Pd‐doped Ti: CMAS glass‐ceramics earlier.