Neutron diffractometry on the structural analysis of Mg-Ni-Zn ferrites prepared through self-propagating high-temperature synthesis

Mg-Ni-Zn ferrites powders with various compositions were synthesized by the combustion reaction of Fe2O3 + xMgO + yNiO + (1 - x - y)ZnO + FeMg(x)Ni(y)Zn1 - x - yFe(2)O(4) in order to develop a high-performance electromagnetic wave absorber in the VHF/UHF region. The reaction mechanism includes the gas-solid reaction among the iron (Fe) and various oxides such as NiO, ZnO, MgO. A neutron diffraction analysis revealed that the final compositions are Mg0.5Ni0.05Zn0.52Fe2O4 and Mg0.4Ni0.21Zn0.39Fe2O4. The lattice parameters are a = 0.839379 and 0.839355 nm, respectively (chi(2) = 3.14 < 3.75). The coercive force, the maximum magnetization, the residual magnetization and the susceptibility Of Mg0.5Ni0.05Zn0.52Fe7O4 amount to 5318A/m, 10.18, 0.81Wb/m(2)kg and 0.015m(3)/kg, respectively. Similar results for Mg(0.4)Ni(0.21)Zn(0.3)qFe(2)O(4) are 7802A/m, 14.97, 1.43Wb/m(2)kg and 0.018m(3)/kg, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.