晶体(NH_4)_2C_4H_4O_6∶VO^(2+)的EPR参量及局域结构的研究

Investigation of EPR Spectra and Local Structure for VO^(2+) in(NH_4)_2C_4H_4O_6 Crystal

采用叠加模型和双旋-轨耦合参量模型,建立了结构参数与EPR参量之间的定量关系;较好地解释了[VO(H2O)5]2+络离子的局域结构和EPR参量;研究结果发现,(NH4)2C4H4O6:VO2+晶体中络离子[VO(H2O)5]2+的键长为R//≈0.130nm,R⊥≈0.195nm;在(NH4)2C4H4O6:VO2+晶体中,局域结构沿C4轴方向呈压缩的八面体结构;所得EPR参量的理论计算与实验测量数据符合很好。

In this work, the relationship between the EPR spectra and the crystal structure parameters is set up. The local structure and EPR spectra of [ VO （H2O）5 ] ^2＋ in （NH4 ）2C4H4O6 single crystal are interpreted simultaneously based on superposition model and two-spin-orbit-coupling parameter model. According to the investigation, the local structure values of [ VO （ H2 O） 5 ] ^2 ＋ are ： bond length R∥≈0.130nm,R⊥≈0.195nm; the local structure around the V^4＋ ions possesses a compressed tetragonal distortion along C4 axis. Theoretical results of EPR spectra are in good agreement with experimental findings.