Synthesis, magnetism, and crystal structure of Li2Fe[(PO4)(HPO4)] and its hydrogen position refinement
- 化学化工－已发表论文 
Lithium iron(III) monophosphate-monohydrogen-monophosphate, Li2Fe[(PO4)(HPO4)], was synthesized under mild hydrothermal conditions and its crystal structure was determined by single crystal X-ray diffraction methods. Crystallographic data: monoclinic, P12(1)/n1 (no. 14), a = 4.8142(2) Angstrom, b = 7.9898(4) Angstrom, c = 7.4868(4) Angstrom, beta = 104.398(3)degrees, V = 278.93(2) Angstrom(3), Z = 2, D-x = 3.104 g (.) cm(-3). The structure is characterized by FeO6 octahedra sharing common O-corners with six neighbouring PO4 tetrahedra to form a three-dimensional framework. Lithium cations are located within channels running along . The channels are formed by eight-membered rings resulting from the connection of alternating FeO6 octahedra (4X) and phosphate tetrahedra (4X). High-resolution diffraction data allowed to refine a split model for the position of the hydrogen atom. Magnetization data confirm the valence state 3+ for iron and detect an antiferromagnetic ordering of the iron moments below 23.6 K. Thermal decomposition of the compound was investigated by DTA/TG methods.