A Ti L -edge X-ray absorption study of Ti-silicate glasses

Environment of titanium and aluminum in a magnesium alumino-silicate glass

“…Similar behavior has been observed by XAS for alkalineearth glasses but with a higher average coordination number of Ti ranging from 4.8 to 5.8 [9,12]. In highly polymerized networks, a significant amount of [4] Ti atoms is present, while it decreases below 10% in highly depolymerized networks.…”

“…All methods used to determine the coordination number distribution for Ti atoms agree on the predominance of [5] Ti, with the coexistence of [4] Ti and [6] Ti in similar amounts. This is an important difference with other alkaline or alkaline-earth silicate glasses (see [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]) that usually present a strong preference for [5] Ti with minor amounts of [4] Ti. This corresponds to several structural positions for titanium atoms within the glass structure, network former or either network modifier.…”

“…In highly polymerized networks, a significant amount of [4] Ti atoms is present, while it decreases below 10% in highly depolymerized networks. As for sixfold-coordinated titanium atoms, their presence remains minor and they are even sometimes excluded [12]. Sodium silicate glasses have a mix of [4] Ti and [5] Ti up to 14.3 wt% TiO 2 , and then only [5] Ti.…”

“…The environment of titanium has been mainly investigated in the TiO 2 -SiO 2 binary system [3][4][5] and Ti-bearing alkali or alkaline-earth silicate glasses [6][7][8][9][10][11][12]. All these studies show that titanium atoms are present in the glass with multiple coordination numbers from four to six.…”

“…TiO 2 -SiO 2 binary glasses have been mainly investigated using Ti K-and L-edges and O K-edge x-ray absorption spectroscopy (XAS) [4,12,13]. At low TiO 2 content (up to 6 mol% TiO 2 ), TiO 2 -SiO 2 glasses contain predominantly fourfold-coordinated titanium atoms, [4] Ti, and Ti is assumed to substitute for silicon in tetrahedral units.…”