The First Vanadate鈥揅arbonate, K2Mn3(VO4)2(CO3): Crystal Structure and Physical Properties

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• 作者：Olga V. Yakubovich ; Ekaterina V. Yakovleva ; Alexey N. Golovanov ; Anatoly S. Volkov ; Olga S. Volkova ; Elena A. Zvereva ; Olga V. Dimitrova ; Alexander N. Vasiliev
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：February 4, 2013
• 年：2013
• 卷：52
• 期：3
• 页码：1538-1543
• 全文大小：394K
• 年卷期：v.52,no.3(February 4, 2013)
• ISSN：1520-510X

文摘

Mixed potassium鈥搈anganese vanadate鈥揷arbonate, K₂Mn₃(VO₄)₂(CO₃), represents a novel structure type; it has been synthesized hydrothermally from the system MnCl₂鈥揔₂CO₃鈥揤₂O₅鈥揌₂O. Its hexagonal crystal structure was determined by single-crystal X-ray diffraction with a = 5.201(1) 脜, c = 22.406(3) 脜, space group P6₃/m, Z = 2, 蟻_c = 3.371 g/cm³, and R = 0.022. The layered structure of the compound can be described as a combination of honeycomb-type modules of [MnO₆] octahedra and [VO₄] tetrahedra, alternating in the [001] direction with layers of [MnCO₃] built by [MnO₅] trigonal bipyramids and [CO₃] planar triangles, sharing oxygen vertices. The K⁺ ions are placed along channels of the framework, elongated in the [100], [010], and [110] directions. The title compound exhibits rich physical properties reflected in a phase transition of presumably Jahn鈥揟eller origin at T₃ = 80鈥?00 K as well as two successive magnetic phase transitions at T₂ = 3 K and T₁ = 2 K into a weakly ferromagnetic ground state, as evidenced in magnetization, specific heat, and X-band electron spin resonance measurements. A negative Weiss temperature 螛 = 鈭?14 K and strongly reduced effective magnetic moment 渭_eff² 70 渭_B² per formula unit suggest that antiferromagnetic exchange interactions dominate in the system. Divalent manganese is present in a high-spin state, S = ⁵/₂, in the octahedral environment and a low-spin state, S = ¹/₂, in the trigonal-bipyramidal coordination.