Na_2O-P_2O_5系晶体微结构形态的拉曼光谱研究及其ab initio计算

Raman Spectroscopic Study and ab initio Calculation of the Micro-Structure of Several Na_2OP_2O_5 Binary Crystals

本文采用激光拉曼光谱仪测量了磷酸钠二元系(1-x)Na2O·xP2O5(x=0.25,0.33,0.50,1.0)几种晶体的拉曼光谱,比较并解释了随化学组成而变化微结构单元的拉曼振动模。同时用Gaussian98W量子化学软件从头计算了这几种化合物的拉曼光谱。实验和计算均表明,磷酸盐晶体的基本结构单元为磷氧四面体犤PO4犦,并且晶体中磷氧四面体的伸缩模振动频率与连接中心磷原子的桥氧数密切相关,随桥氧数增加而升高。此外还解释了模拟图谱与实验谱差异的原因。

Raman spectra of several (1 - x) Na2O . xP(2)O(5) (x = 0.25, 0.33, 0.50, 1.0) crystals were determined. Raman vibrational modes were assigned and also calculated by ab initio calculation method with Gaussian 98W software. Results show that calculation results agree well with those of experiment and phosphor-us-oxygen tetrahedrons are the micro-structure units of those crystals along with different number of bridging oxygen connected to each centre phosphor-us atom. The number of bridging oxygen are 0, 1, 2 and 3 for Na3PO4, Na4P2O7, NaPO3 and P2O5 crystals, respectively. The frequencies of stretching vibrational modes dependent on the number of bridging oxygen and increase with the P2O5 content in crystal. Difference between the computational and experimental spectra is also discussed.