Structure and electrical properties of the spin 1/2 onedimensional antiferromagnet Ca2CuO3 prepared by the sol-gel technique

Abstract

Highly homogeneous finely powdered Ca2CuO3 has been prepared by the sol-gel technique. No evidence for CaO and CuO impure phases was observed. The single-phase purity was observably better than that of samples prepared by the ceramic method and oxalate co-precipitation. On the basis of the structural parameters determined, the bond valence sum approach was involved in explaining the weak interchain direct Cu-Cu covalent bonding. The I-V and ?(T) measurements showed constant semiconductor behaviour with resistivity increase above 108??cm in the low temperature region. The fitting of ?(T) using a band gap model gave an activation energy as small as 0.19eV. This finding demonstrates well the covalent insulator nature of this system. ?? 2007 IOP Publishing Ltd.