PbBr2-PbF2-P2O5玻璃的结构研究

采用红外光谱(IR)和X射线光电子能谱(XPS)等方法研究了PbBr₂-PbF₂-P₂O₅系铅卤磷酸盐玻璃的结构.结果表明,Pb²⁺离子在玻璃中起着网络修饰阳离子和网络形成体的双重作用.当P₂O₅含量为60mol％时,Pb²⁺离子主要是作为网络修饰体;当P₂O₅含量降低到50mol％时,一部分Pb²⁺离子能够进入玻璃网络形成PbO₄]四面体或P-O-Pb键.Br^-和F^-离子达到一定浓度时就会进入玻璃网络,形成PO_4-nX_n](X=Br或F,n=0-4)四面体使磷酸盐链长变短.玻璃中P₂O₅的含量不变时P-O-P键的比例也基本保持不变;当P₂O₅的含量降低时,P-O-P键和P-O^-键的含量都减少,P-O-Pb键的含量则明显增加.

Structure Studies of PbBr2-PbF2-P2O5 Glasses

Glasses in the system of PbBr₂-PbF₂-P₂O₅ have low melting temperature, good water durability and good optical properties, which can serve as the host materials of organic-doped scintillator. In the present paper, the structure of PbBr₂-PbF₂-P₂O₅ glasses was characterised by Fourier transfer infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Results show that lead ions play dual roles, network former and network modifier, in the structure of PbBr₂-PbF₂-P₂O₅ glasses. When P₂O₅ content is 60mol%, most of Pb²⁺ ions act as network modifier. When P₂O₅ content decreases to 50mol% and even 40mol%, some Pb²⁺ ions could enter glass network and form PbO₄] tetrahedron or P--O--Pb linkage with decreasing P_₂O_₅ content, while other Pb²⁺ ions still act as network modifier. The length of phosphate chains decreases with decreasing P₂O₅ content. Both Br^- and F^- ions could enter glass network and form PO_4-nX_n](X=Br or F, n=0～4) tetrahedron when they reach certain content, breaking PO₄] tetrahedron and decreasing the length of phosphate chains. The P--O--P linkages content keep unchanged with the same P₂O₅ content. Decreasing P₂O₅ content and increasing lead halide content lead to the formation of P--O--Pb linkage through the delocalization of P=O and P--O^- bonds.