Technical University of Cluj-Napoca, B-dul Muncii, nr. 103-105, 400641 Cluj-Napoca, Romania.
Spectrochim Acta A Mol Biomol Spectrosc. 2010 Nov;77(4):832-7. doi: 10.1016/j.saa.2010.08.014. Epub 2010 Aug 12.
Glasses and glass ceramics in the system xMoO₃·(100 - x)[3B₂O₃·PbO] with 0 ≤ x ≤ 30 mol% have been prepared from melt quenching method and characterized by means of X-ray diffraction, FTIR, UV-VIS and EPR spectroscopy. We have examined and analyzed the effects of systematic molybdenum ions intercalation on lead-borate glasses and glass ceramics with interesting results. The observations present in these mechanisms show the lead ions bonded ionic have a strong affinity towards [BO₃] units containing non-bridging oxygens and [MoO₄]²⁻ molybdate units. The pronounced affinity towards molybdate anions yields the formation of the PbMoO₄ crystalline phase. Then, the excess of oxygen can be supported into the glass network by the formation of [MoO₆] and [Mo₂O₇] structural units. Pb²(+) ions with 6s² configuration show strong absorption in the ultraviolet due to parity allowed s²-sp transition and yield an absorption band centered at about 310 nm. The changes in the features of the absorption bands centered at about 310 nm can be explained as a consequence of the appearance of additional absorption shoulder due to photoinduced color centers in the glass such as the formation of borate-molybdate and lead-molybdate paramagnetic defect centers in the glasses. The concentration of molybdenum ions influences the shape and width of the EPR signals located at g ∼ 1.86, 1.91 and 5.19. The microenvironment of molybdenum ions in glasses is expected to have mainly sixfold coordination. However, there is a possibility of reduction of a part of molybdenum ions from the Mo⁶(+) to the Mo⁵(+) and Mo⁴(+) to the Mo³(+) states.
系统 xMoO₃·(100 - x)[3B₂O₃·PbO]（0 ≤ x ≤ 30 mol%）中的玻璃和玻璃陶瓷是通过熔融淬火法制备的，并通过 X 射线衍射、FTIR、UV-VIS 和 EPR 光谱进行了表征。我们研究并分析了系统钼离子嵌入对含有趣结果的铅硼酸盐玻璃和玻璃陶瓷的影响。这些机制中的观察表明，键合离子的铅离子与含有非桥氧的[BO₃]单元和[MoO₄]²⁻ 钼酸盐单元具有强烈的亲和力。对钼酸盐阴离子的强烈亲和力导致 PbMoO₄ 晶相的形成。然后，多余的氧可以通过形成[MoO₆]和[Mo₂O₇]结构单元进入玻璃网络。具有 6s² 构型的 Pb²(+)离子由于允许的奇偶 s²-sp 跃迁而在紫外光区显示出强烈的吸收，并在约 310nm 处产生吸收带。约 310nm 处的吸收带特征的变化可以解释为由于玻璃中光致色心的出现而导致额外的吸收肩的出现，例如硼酸盐-钼酸盐和铅-钼酸盐顺磁缺陷中心的形成。钼离子的浓度影响位于 g ∼ 1.86、1.91 和 5.19 处的 EPR 信号的形状和宽度。玻璃中钼离子的微环境预计主要具有六配位。然而，一部分钼离子可能从 Mo⁶(+)还原为 Mo⁵(+)和 Mo⁴(+)还原为 Mo³(+)。
