辺共有一次元鎖化合物Cu_2GeO_4の合成と磁性 Synthesis and magnetic property of Cu_2GeO_4 containing edge-sharing CuO_2 chains
Polycrystals of Cu<SUB>2</SUB>GeO<SUB>4</SUB> have been synthesized under high pressure (4 GPa) and high temperature (900°C) conditions. It has the tetragonally distorted spinel structure with CuO<SUB>6</SUB> octahedra elongated along the c axis due to the Jahn-Teller effect. The crystal structure is apparently three-dimensional, but the major superexchange path is assumed to be one-dimensional along the edge sharing chains. In fact, the magnetic susceptibility of Cu<SUB>2</SUB>GeO<SUB>4</SUB> shows a broad maximum around 100 K and is well described as that of the S=1/2 Heisenberg antiferromagnetic chains with interaction J of 135 K. A small jump in the susceptibility curve is observed at 33 K, which is considered to be a sign of antiferromagnetic ordering. Moreover, specific heat measurements show a large sharp peak at the same temperature, suggesting a first-order phase transition. The effects of Mg substitution for Cu and Si substitution for Ge are also reported.
粉体および粉末冶金 45(12), 1136-1141, 1998-12-15
Japan Society of Powder and Powder Metallurgy