PbBr_2-PbF_2-P_2O_5玻璃的结构研究

Structure Studies of PbBr_2-PbF_2-P_2O5 Glasses

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[PO4-nXn](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.

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 P2O5 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 [PO4-nXn](X=Br or F, n=0similar to4) 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.