三氧化二硼和五硼酸钠水合物非晶结构

X射线衍射法测量了三氧化二硼及五硼酸钠水合物的非晶结构, 通过非晶衍射实验数据处理, 得到了它们的径向分布函数(RDF). 模型定量计算, 得到了其短程有序结构, 三氧化二硼水合物非晶中75%的硼参与形成平面硼氧六元环(boroxol), 给出了环内ortho-B-O, meta-O-O, meta-B-B和para-B-O相互作用的距离和作用数, 支链与硼氧六元环之间的夹角为125°±15°; 五硼酸钠水合物非晶中, 由两个硼氧三角形(B_△)和一个硼氧四面体(B_□)构成的两个变形六元环通过公共顶点(B_□)相连而形成五硼酸阴离子, 高度有序的离子内相互作用占绝对优势. 六配位Na^＋与五硼酸阴离子中一端氧相连, Na-B特征距离为0.330 nm.

Amorphous Structure of Diboron Trioxide and Sodium Pentaborate Hydrate

We determined the structures of amorphous diboron trioxide and sodium pentaborate hydrate by X-ray diffractometry. Radial distribution functions (RDF) of those samples were obtained from precisely diffraction data processing. Their short-range ordered structures were determined by model design and quantitative calculations. In amorphous diboron trioxide hydrate, 75% of boron atoms construct planar six-membered boroxol ring and the interatomic distance and the interactions numbers of intra-ring ortho-B—O, meta-O—O, meta-B—B and para-B—O were listed out, where boron-oxygen branched-chain intersects with the plane at a terminal-oxygen with a intersect angle of 125°±15°. The basic structure unit of non-crystalline sodium pentaborate hydrate is formed by two planar six-membered boroxol rings deformed, composed of two boron-oxygen triangles (B_△) and a boron-oxygen tetrahedron (B_□), through the shared B_□. The highly ordered intra-anion interactions are the upmost interactions. Six coordinated Na^＋ connects with the terminal-oxygen of pentaborate to form a contact ion pair with a characteristic distance (B—Na) of 0.330 nm.