| 摘 要： | Room temperature EXAFS spectra of a series ofgallium phosphate glasses have been obtained in alaboratory EXAFS facility.Fourier transform isemployed for EXAFS data analysis.Low-cristobalitetype GaPO_4 crystal is used as a standard specimento extract the local structure parameters of Gaatoms in Ga_2O3-P_2O_5 glasses.The Ga-O average bondlength is 1.75-1.86 and Ga atoms can form both[GaO_4] tetrahedra and [GaO_6] octahedra in some ofthese glasses.The coordination number of Ga atomschanges from six to four with the increase of Ga_2O_3content,and this change becomes more significantwhen the Ga_2O_3 content exceeds 30mol%.The anomalouschange of the refractive index at 30mol% Ga_2O_3 iscaused by the change of the local structure of Gafrom [GaO_6] octahedra to [GaO_4] tetrahedra.A simpleformula to estimate the concentration of six foldcoordinated Ga atoms in glasses is derived based onaverage bond length measured from the EXAFS.
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