期刊名称：Journal of Materials and Environmental Science
印刷版ISSN：2028-2508
出版年度：2018
卷号：9
期号：11
页码：3009-3018
出版社：University of Mohammed Premier Oujda
摘要：Nasiglasses with formula Na3Ca1-xMnxTi(PO4)3 (0 ≤ x ≤ 1) were synthesized andstructurally characterized by DTA, PXRD, EPR, Raman, and density measurements.The density of these glasses increases while the molar volume remains practicallyconstant when manganese replaces calcium, indicating that manganese ions are locatedin!the interstitial sites of the framework, in good agreement with the small variation ofthe glass transition temperature, observed between the extreme compositions (ΔTg = 23°C). Crystallization of the glasses at 650 °C leads to the formation of crystalline phasesbelonging to the Nasicon family. The structure of these crystalline phases consists ofthree dimensional framework built of PO4 tetrahedra sharing corners with AO6octahedra (A = Ca/Mn, Ti); Na ions occupy the interstitial sites. EPR study of glassesshows that Mn2 ions occupy octahedral sites, with predominantly ionic bondingbetween Mn2 and O-2 ions. Raman spectroscopy study shows that the glasses containP2O7 and PO4 groups, and short -Ti-O-Ti-O-Ti- chains. The presence of these chainsindicates that the TiO6 octahedra are linked to each other through corners, unlike in thecorresponding crystalline phases where they are connected to each-other via PO4tetrahedra. All results obtained for the glassy materials indicate that Mn2 and Ca2 ionsact as glass modifiers, unlike in the crystalline compounds where they are part of theframework.
