Ternary and quaternary layered nitride halides, Ca2N(X,X′) (X,X′=Cl, Br, I): Evolution of structure with composition
Ternary and quaternary layered nitride halides, Ca2N(X,X′) (X,X′=Cl, Br, I): Evolution of structure with composition
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DOI：
10.1016/j.jssc.2005.03.021
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发表时间：
2005-06
影响因子：
3.3
通讯作者：
A. Bowman;Ronald I. Smith;D. Gregory
中科院分区：
文献类型：
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作者：
A. Bowman;Ronald I. Smith;D. Gregory
本文研究了四元体系Ca-N-Cl-Br和Ca-N-Br-I，合成了一系列新的层状氮化物混合卤化物。用粉末X射线和粉末中子衍射技术研究了结构随成分的演变。Ca 2NCl和Ca 2NBr之间存在连续固溶体，中间化合物具有与三元端元相同的反- α-NaFeO 2结构（菱形空间群R3 <$m）。Ca 2NBr 1 − yIy系统在y=0.7和y=0.8之间发生相变，对应于金属-氮层从立方密堆积到六方密堆积的转变，以及相应的反β-RbScO 2（填充反CdI 2）结构（六方空间群P63/mmc）的采用。虽然氮化物和卤化物阴离子占据不同的晶体学位点，但无论化学计量或结构类型如何，四元材料中的卤化物都没有顺序。所有的氮化物卤化物显示温度无关的顺磁行为在2和300 K之间。
The quaternary systems Ca–N–Cl–Br and Ca–N–Br–I have been investigated resulting in the synthesis of a number of new layered nitride mixed halides. The evolution of structure with composition has been investigated by powder X-ray and powder neutron diffraction techniques. A continuous solid solution exists between Ca2NCl and Ca2NBr with intermediate compounds adopting the same anti- α-NaFeO2structure (rhombohedral space group R3¯m) as the ternary end members. A phase transition occurs in the Ca2NBr1−yIysystem between y=0.7 and y=0.8 corresponding to a switch from cubic close packing to hexagonal close packing of metal–nitrogen layers and corresponding adoption of the anti-β-RbScO2(filled anti-CdI2) structure (hexagonal space group P63/mmc). While nitride and halide anions occupy distinct crystallographic sites, there is no ordering of halides in quaternary materials irrespective of stoichiometry or structure type. All the nitride halides show temperature independent paramagnetic behaviour between 2 and 300K.