Structure of Na<sub>2sub>O路MO路SiO<sub>2sub>路CaF<sub>2sub> (M=Mg, Ca) oxyfluoride glasses
- 作者：Jin-shu Cheng<sup>asup><sup> ; sup><sup>1sup> ; Wei Deng<sup>asup><sup> ; sup><sup>1sup><sup> ; sup><sup>dengwei@whut.edu.cnsup><sup> ; sup><sup>dengwei19@gmail.comsup> ; Mi-tang Wang<sup>bsup>
- 关键词：Silicate glass structure ; Alkaline metal oxides ; NMR ; Raman
- 刊名：Physica B
- 出版年：2012
- 期刊代码：53_09214526
- 类别：ph
- 出版时间：15 July, 2012
- 卷：407
- 期：14
- 页码：2778-2783
- 文件大小：630 K
摘要
(9鈭?em>xm>)CaO路m>x m>MgO路15Na<sub>2sub>O路60SiO<sub>2sub>路16CaF<sub>2sub>(m>x m>=0, 2, 4, 6, and 9) oxyfluoride glasses were prepared. Utilizing the Raman scattering technique together with <sup>29sup>Si and <sup>19sup>F MAS NMR, the effect of alkaline metal oxides on the Q species of glass was characterized. Raman results show that as magnesia is added at the expense of calcium oxide, the disproportional reaction Q<sup>3sup>鈫扱<sup>4sup>+Q<sup>2sup> (Q<sup>m>n m>sup> is a SiO<sub>4sub> tetrahedron with m>n m> bridging oxygens) prompted due to the high ionic field strength of magnesia, magnesium oxide entered into the silicate network as tetrahedral MgO<sub>4sub>, and removed other modifying ions for charge compensation. This reaction was confirmed by <sup>29sup>Si MAS NMR. <sup>19sup>F MAS NMR results show that fluorine exists in the form of mixed calcium sodium fluoride species in all glasses and no Si-F bonds were formed. As CaO is gradually replaced by MgO (m>x m>=6, 9), a proportion of the magnesium ions combines with fluorine to form the MgF<sup>+sup> species. Meanwhile, some part of Na<sup>+sup> ions complex F<sup>鈭?/sup> in the form of F-Na(6).