EPR study of coordination of Ag and Pb cations in BaB<Subscript>2</Subscript>O<Subscript>4</Subscript> crystals and barium borate glasses     

V. P. Solntsev  R. I. Mashkovtsev  A. V. Davydov  E. G. Tsvetkov 《Physics and Chemistry of Minerals》2008,35(6):311-320

It is shown the possibility to determine the coordination of paramagnetic ions in disordered solid structures, e.g., in barium borate glasses. For this purpose the electron paramagnetic resonance (EPR) method was used to study α-and β-BaB₂O₄ crystals and glasses of 45·BaO × 55·B₂O₃ and 40·BaO × 60·B₂O₃ (mol%) composition activated by Ag⁺ and Pb²⁺ ions. After the samples were exposed to X-rays at 77 K, different EPR centers were observed in them. In α-and β-BaB₂O₄ crystals and glasses the EPR centers Ag²⁺, Ag⁰, Pb⁺, Pb³⁺, and hole centers of O⁻ type were studied. The EPR parameters of these centers and their arrangement in crystal structure were determined. It is shown that Pb³⁺ ions in β-BaB₂O₄ crystals occupy Ba²⁺ position in an irregular polyhedron from the eight oxygen, whereas in α-BaB₂O₄ crystals they occupy Bа₂ position in a sixfold coordination. Pb⁺ ions in α-BaB₂O₄ crystals occupy Bа₁ position in a ninefold coordination from oxygen. In barium borate glasses, Pb³⁺ ions were studied in coordination polyhedron from six oxygen atoms and in a polyhedron from nine to ten oxygen atoms. It is assumed that the established difference in the structural position of Pb³⁺ ions in glasses is due to their previous incorporation in associative cation–anion complexes (AC) and “free” structure-forming cations (FC). Computer simulations have been performed to analyze the stability of specific associative complexes and to compare their bond lengths with experimental data.  相似文献   

盐卤硼酸盐化学Ⅹ　Ⅹ　Ⅴ　Ⅲ硼氧酸盐结晶液固相硼同位素组成          下载免费PDF全文

李军  高世扬  肖应凯 《盐湖研究》1995,(3)

实验研究了硼氧酸盐在水溶液结晶沉淀后液固相硼同位素组成，结果表明，硼氧酸盐结晶固相的硼同位素组成与溶液相ｐＨ、总硼浓度及析出固相后固液相硼摩尔比有关，不仅存在正的硼同位素分馏效应，而且存在负的硼同位素分馏效应。  相似文献   

A Rapid Synthetic Method for Inderite     

LI Fei  ZHANG Sisi  GUO Yafei  WANG Shiqiang  DENG Tianlong 《《地质学报》英文版》2014,88(Z1):343-344

正1 Introduction There are many different magnesium borates synthesized from various conditions or acquired naturally with different compositions,which can be used in a wide range of fields.Their applications involve ceramic  相似文献   

硼氧酸盐^11BNMR波谱学研究   总被引：1，自引：0，他引：1       下载免费PDF全文

李军  李武 《盐湖研究》1995,3(4):72-80

系统地总结和讨论了固体硼氧酸盐１１ＢＭＡＳＮＭＲ和硼氧酸盐水溶液１１ＢＮＭＲ波谱学研究结果。对于固体硼氧酸盐１１ＢＭＡＳＮＭＲ谱．虽然可以从中定量计算ＢＯ３与ＢＯ４比值，但因为１１Ｂ化学位移变化小，很难将配位多面体与它们的配位环境相联系，用其作为表征固体硼氧酸盐尚缺少特征性。而对于硼氧酸盐水溶液１１ＢＮＭＲ谱，由于在ＮＭＲ谱仪时间规模下一些硼氧酸盐阴离子中不同化学位置上Ｂ核交换速率影响，在１１ＢＮＭＲ波谱上没有观察到信号。实践证明，溶液１１ＢＮＭＲ波谱与Ｒａｍａｎ光谱的联合使用，将是研究水溶液中硼氧酸盐阴离子结合最直接和有力的手段。  相似文献