Defect dependent optical, electrical and magnetic properties of nanostructured Mn3O4

Nanostructured Mn3O4 sample with an average crystallite size of similar to 12 nm was synthesized through a microwave assisted synthesis route. The average particle size obtained from the transmission electron microscopy analysis is 19 nm. The existence of Mn4+ ions at the octahedral sites is evident from the Raman, UV-Visible absorption and X-ray photoelectron spectroscopy analyses. The DC electrical conductivity is larger than that reported for single crystalline Mn3O4 and the conduction mechanism is the polaronic hopping of holes between cations in the octahedral sites. Study of magnetization of the sample reveals an increase in the Curie temperature (55 K) in comparison with that of single crystalline Mn3O4 due to nanoscaling and surface effects. The analysis of field dependent magnetization at different temperatures assuming a modified Langevin relation reveal the presence of magnetically ordered core and surface with canted spin arrangement. (C) 2015 Elsevier Ltd. All rights reserved.