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 ρ(T) measurements showed constant semiconductor behaviour with resistivity increase above 10⁸Ωcm in the low temperature region. The fitting of ρ(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.

Huynh D.-C., Ngo D.-T., Hoang N.-N.

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Từ khóa : Activation energy; Calcium compounds; Electric properties; One dimensional; Precipitation (chemical); Sol-gel process; Co-precipitation; Low temperature region; Oxalates; Single-phase purity; Antiferromagnetic materials