摘要
用X射线晶体学和把三价铕离子作为结构探子的方法,研究了Na_3Eu(PO_4)_2的相变和晶体结构。这个化合物存在四种同素异形变体:一种属于六方晶系的高温变体α;两种皆为正交晶相的结构近似的中间变体β和β′和一种属于单斜晶系的低温变体γ。它们的相变和晶体结构与Ca_2SiO_4和Sr_2SiO_4等同类的化合物有相似之处。在β变体中存在结构元序现象。β变体和要β′变体之间的差别只有通过低温下Eu^(3+)离子的~5D_0-~7F_0发射光谱分析才能辨认。
The thermal behavior and crystalline structure of sodium europium orthophosphate were investigated by radiocrystallography and using trivalent europium as a strutural local probe. Four allotropic varieties exist in this compound: a hexaconal form of hight temperature a, a monoclinic type of low temperature γ and two orthorhombic phases of intermediate temperature β and β′. Their allotropic transformation and crystalline structure are very similar to that of Ca_2SiO_4 and Sr_2SiO_4. The β variety presents certain structural disorder. The distinction between the β and β′ phase can be made only by studing the emission spectre of Eu^(3+) in low temperature.
关键词
发光材料
晶体结构
稀土族
luminophor
rare earth compound
allotropic■ ri■ ture
orthophosphate of europium and sodium
struetural localproi■
