Two Isotypic Transition Metal Germanophosphates MII4(H2O)4[Ge(OH)2(HPO4)2(PO4)2] (MII = Fe, Co): Synthesis, Structure, Mössbauer Spectroscopy, and Magnetic Properties
journal contribution
posted on 2012-03-05, 00:00 authored by Ya-Xi Huang, Xin Zhang, Xuan Huang, Walter Schnelle, Jun Lin, Jin-Xiao Mi, Mei-Bo Tang, Jing-Tai ZhaoSynthetic, structural, thermogravimetric, Mössbauer
spectroscopic, and magnetic studies were performed on two new isotypic
germanophosphates, MII4(H2O)4[Ge(OH)2(HPO4)2(PO4)2] (MII =
Fe, Co), which have been prepared under hydro-/solvo-thermal conditions.
Their crystal structures, determined from single crystal data, are
built from zigzag chains of MIIO6-octahedra sharing either trans or skew edges interconnected by [GeP4O14(OH)4]8– germanophosphate
pentamers to form three-dimensional neutral framework structure. The
edge-sharing MIIO6-octahedral
chains lead to interesting magnetic properties. These two germanophosphates
exhibit a paramagnetic to antiferromagnetic transition at low temperatures.
Additionally, two antiferromagnetic ordering transitions at around
8 and 6 K were observed for cobalt compound while only one at 19 K
for the iron compound. Low-dimensional magnetic correlations within
the octahedral chains are also observed. The divalent state of Fe
in the iron compound determined from the Mössbauer study and
the isothermal magnetization as well as thermal analyses are discussed.
