Coordination of yttrium in rf-sputtered amorphous films in the system SiO2-Y2O3

Extended X-ray absorption fine structure near the Y Ii-edge was measured to determine the coordination state of yttrium ions in amorphous films in the system SiO2-Y2O3 prepared by rf-sputtering. The coordination number of yttrium inns in the amorphous films with < 30 mol% Y2O3 content was greater than sis, but it approached six, dependent on the Y2O3 content, in the region > 35 mol% Y2O3 content. That is, the region between about 35 mol% and about 50 mol% Y2O3 content is the transition stage of the change of the coordination number of yttrium ions. This result of the coordination state of yttrium ions has given a direct proof for the prediction that the coordination state of yttrium ions changes at about 45 mol% Y2O3 content in SiO2-Y2O3 amorphous films, which was obtained from our previous study about their physical properties, such as density and elastic-moduli. (C) 1997 Elsevier Science B.V.