钨酸盐晶体中负离子配位多面体的结晶方位与晶体的形貌

Relationship between the Orientations of Tetrahedral [WO_4]^(2-) in Tungstate Crystals and Their Morphology

钨酸盐类晶体是重要的闪烁晶体．本文从钨酸盐类晶体中负离子配位多面体的结晶方位和相互联结的稳定性出发，探讨了钨酸盐类晶体中[WO4]2-等负离子配位多面体的结晶方位与晶体结晶形貌之间的关系；认为[WO4]2-四面体与金属阳离子（Ca2＋，Pb2＋，Zn2＋）结合时，由于晶体结构和生长条件（如籽晶取向等）的不同，在晶体各族晶面上的叠合速率和结构取向不同，晶体的结晶形貌迥然有别；四面体的面和梭的法线（L2）所对向的晶面，生长速率慢，顽强显露，均属晶体的板面；四面体的顶角所指向的晶面，生长速率快，显露面积小，经常消失．由此可以合理解释钨酸铅等闪烁晶体的生长特征．最后对ABO4型晶体的结构及习性特征进行了总结归纳．

The relationship between the orientations of tetrahedral [WO4]2- in tungstate crystals withthe scheelite and wolframite structures such as CaWO4 , PbWO4, NaBi(WO4)2, CdWO4, ZnWO4and FeWO4 , which are all the important scintillation materials, and their morphology was studiedfrom the standpoint of crystal chemistry, and the formation mechanisms of their morphology wereanalysed according to the structural orientations of tetrahedral [WO4]2- and the bonding energiesbetween [WO4]2- and metal ions [M2+ ] during growth. It is shown that the morphology oftungstates is related to the orientations of structural units [WO4]2- and [M-O6] or [M-O8] inthese crystals and similar to that of sulfates. The structural features of ABO4 compounds werecompared, and the relationships between structures and growth habits discussed.