A new phase in the system lithium–aluminum: Characterization of orthorhombic Li2Al
A new phase in the system lithium–aluminum: Characterization of orthorhombic Li2Al
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DOI：
10.1016/j.jssc.2010.08.029
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发表时间：
2010-11
影响因子：
3.3
通讯作者：
K. Puhakainen;M. Boström;T. Groy;U. Häussermann
中科院分区：
文献类型：
--
作者：
K. Puhakainen;M. Boström;T. Groy;U. Häussermann
对二元Li - al体系富Li部分的研究发现，存在一种与Li2Ga和Li2In同构的新相——正交Li2Al。晶体结构由x射线单晶衍射数据确定(Cmcm, a=4.658(2)Å， b=9.767（4)Å， c=4.490(2)Å， Z=4）。原子位置占位的细化得到Li1.92Al1.08(64at% Li)，表明均匀性范围小，Li2−xAl1+x。Li2Al是化学计量化合物Li9Al4的包晶分解产物，在270±2℃以下稳定。Li2Al本身在335±2°C时分解为li3al2，富Li熔化。Li2Al （Li2−xAl1+x）的发现解决了长期以来基于li9al4具有高温改性假设的Li-Al相图不一致的问题。
Investigation of the Li rich part of the binary Li–Al system revealed the existence of a new phase, orthorhombic Li2Al, which is isostructural to Li2Ga and Li2In. The crystal structure was determined from single crystal X-ray diffraction data (Cmcm, a=4.658(2)Å, b=9.767(4)Å, c=4.490(2)Å, Z=4). Refinement of atomic position site occupancies yielded a composition Li1.92Al1.08(64at% Li) indicating a small homogeneity range, Li2−xAl1+x. Li2Al is the peritectic decomposition product of the stoichiometric compound Li9Al4, which is stable below 270±2°C. Li2Al itself decomposes peritectically to Li3Al2and Li rich melt at 335±2°C. The discovery of Li2Al (Li2−xAl1+x) settles a long standing inconsistency in the Li–Al phase diagram which was based on the assumption that Li9Al4possesses a high temperature modification.