Prakash P Giri, Rao J Lakshmana
Department of Physics, Sri Venkateswara University, Tirupati 517502, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2005 Sep;61(11-12):2595-602. doi: 10.1016/j.saa.2004.09.025. Epub 2004 Nov 19.
Electron paramagnetic resonance (EPR) and optical absorption spectra of vanadyl ions in zinc lead borate (ZnO-PbO-B2O3) glass system have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of VO2+ ions. The values of spin-Hamiltonian parameters indicate that the VO2+ ions in zinc lead borate glasses were present in octahedral sites with tetragonal compression and belong to C4V symmetry. The spin-Hamiltonian parameters g and A are found to be independent of V2O5 content and temperature but changing with ZnO content. The decrease in Deltag( parallel)/Deltag( perpendicular) value with increase in ZnO content indicates that the symmetry around VO2+ ions is more octahedral. The decrease in intensity of EPR signal above 10 mol% of V2O5 is attributed to a fall in the ratio of the number of V4+ ions (N4) to the number of V5+ ions (N5). The number of spins (N) participating in resonance was calculated as a function of temperature for VO2+ doped zinc lead borate glass sample and the activation energy was calculated. From the EPR data, the paramagnetic susceptibility was calculated at various temperatures and the Curie constant was evaluated from the 1/chi-T graph. The optical absorption spectra show single absorption band due to VO2+ ions in tetragonally distorted octahedral sites.
研究了锌铅硼酸盐（ZnO-PbO-B₂O₃）玻璃体系中钒酰离子的电子顺磁共振（EPR）和光吸收光谱。所有玻璃样品的EPR光谱均显示出VO²⁺离子的共振信号特征。自旋哈密顿参数值表明，锌铅硼酸盐玻璃中的VO²⁺离子存在于具有四方压缩的八面体位点，属于C₄V对称性。发现自旋哈密顿参数g和A与V₂O₅含量和温度无关，但随ZnO含量而变化。随着ZnO含量的增加，Δg（平行）/Δg（垂直）值降低，这表明VO²⁺离子周围的对称性更接近八面体。当V₂O₅含量超过10 mol%时，EPR信号强度降低归因于V⁴⁺离子数（N₄）与V⁵⁺离子数（N₅）之比的下降。计算了VO²⁺掺杂的锌铅硼酸盐玻璃样品参与共振的自旋数（N）随温度的变化函数，并计算了活化能。根据EPR数据，计算了不同温度下的顺磁磁化率，并从1/χ-T图中评估了居里常数。光吸收光谱显示，在四方畸变的八面体位点中，VO²⁺离子产生单一吸收带。
