Effect of Mg2+ coordination on the structural and optical properties of iron magnesium phosphate glasses

Abstract

The O2− anions coordination by 3-5 of Mg2+ cations is the origin of Mg-rich cluster formation and photoemission properties of magnesium metaphosphate glasses. XRD, SAED and TEM analyses exhibit that Mg-rich clusters are of amorphous structure. The replacement of MgO by Fe2O3 results in the formation of crystalline Fe-rich regions. FTIR spectra reveal that Fe2O3 acts as network former and/or modifier by forming FeO4 and/or FeO6 groups, respectively. EDX mapping reveals that these Mg-rich clusters are disappeared at the expense of iron-rich clusters formation. UV-Vis absorption and fluorescence spectroscopies demonstrate that such coordination behavior is the reason for the photoemission of presented magnesium phosphate amorphous structure. Furthermore, replacement of Fe2O3 by MgO leads to photoemission quenching, which is assigned to the formation of Fe-rich clusters.