Synthesis, structure, and magnetic behavior of nanoparticles of cubic ZnMnO3

Synthesis and nature of magnetism in ZnMnO3 nanoparticles with cubic spinel structure (a = 8.369 angstrom and size D similar or equal to 25 nm) are reported. Magnetization M vs. H and M vs. T data yield ferrimagnetism with T-N similar or equal to 20 K mu/Mn = 4.46 mu(B), M-S similar or equal to 18.5 emu/g, and a transition at T-S similar or equal to 7K. For T < T-N, coercivity and exchange-bias approach zero at T-N with anomaly at T-S. Using magnetic data and simulations, structure of [Zn2+][Zn1/32+Mn2/33+Mn2/34+square(1)/(3)]O-11/3 with antiparallel moments of Mn4+ and Mn3+ is proposed. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4729817]