title: Preparation and magnetic properties of multiferroic CuMnO2 nanoparticles.
abstract: CuMnO2 nanoparticles with diameters of 64 nm were synthesized by a novel wet chemical method. An optimized two-step annealing method was developed through the analysis of thermogravimetric differential thermal analysis (TG-DTA) measurements in order to obtain single-phase CuMnO2. A sharp exothermic peak was observed in the DTA curve at approximately 500 K where structural changes of the copper oxides and manganese oxides in the precursor are expected to occur. It is believed that Cu+ ions were oxidized to Cu2+ ions and that Mn2+ ions were oxidized to Mn3+ ions in the Cu-Mn-O system. Deoxidization reactions were also found at approximately 1200 K. The optimized annealing temperature for the first step was determined to be 623 K in air. The optimized annealing temperature for the second step was 1173 K in an Ar atmosphere. Magnetization measurements suggested an antiferromagnetic spin ordering at approximately 50 K. It was expected that Mn3+ spin interactions induced magnetic phase transition affected by definite temperature.
authors.forename: Akinobu
authors.initials: A
authors.lastname: Kurokawa
authors.forename: Tkuya
authors.initials: T
authors.lastname: Yanoh
authors.forename: Shinya
authors.initials: S
authors.lastname: Yano
authors.forename: Yuko
authors.initials: Y
authors.lastname: Ichiyanagi