Preparation and magnetic properties of multiferroic CuMnO2 nanoparticles

• Published in: Journal of nanoscience and nanotechnology Vol. 14; no. 3; p. 2553
• Main Authors: Kurokawa, Akinobu, Yanoh, Tkuya, Yano, Shinya, Ichiyanagi, Yuko
• Format: Journal Article
• Language: English
• Published: United States 01.03.2014
• ISSN: 1533-4880
• DOI: 10.1166/jnn.2014.8550

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.