Portal de Periódicos da CAPES

Hydrothermal synthesis, structure, stability and magnetism of Na2Co2(C2O4)3(H2O)2: a new metal oxalate ladder †

2000; Issue: 20 Linguagem: Inglês

10.1039/b005494l

1470-479X

D.J. Price, Annie K. Powell, Paul T. Wood,

Theoretical and Computational Physics

Purple crystals of the compound Na2Co2(C2O4)3(H2O)21 were synthesized in high yielding hydrothermal reactions. The room temperature crystal structure reveals an anionic cobalt oxalate network with a 2-leg ladder topology. The ladder frameworks run parallel to the a axis and are held together by both hydrogen bonding and electrostatic interactions. The magnetism of 1 was studied as a function of temperature and field. The susceptibility shows a broad maximum at about 21 K which is associated with short-range correlations, and a phase transition to a long range ordered Néel state at about 9 K. Above TN the data are fitted by a range of models which suggests the intra-ladder couplings are of the order −4 to −5 cm−1 and the inter-ladder coupling is approximately 0.2 cm−1. Themogravimetric analysis shows 1 to be stable up to 350 °C, where water of crystallisation is lost. A second decomposition episode is seen at 400 °C.