Preparation of Nickel Thin Sheets with Nanosized Ferrites by Combustion Synthesis and Electroforming

Composite nickel sheets with nanosized nickel-zinc ferrite particles were prepared as electromagnetic shielding materials by electroforming in a modified nickel-sulfate bath with nickel-zinc ferrite particles. The nanosized nickel-zinc ferrites were prepared by combustion synthesis and mechanical milling. The combustion temperature and propagation rate were about 1150 degrees C and 8.9 mm/s, respectively. Neutron diffractometry revealed that the final nickel-zinc ferrites formed by combustion synthesis followed by mechanical milling were Ni0.42Zn0.58Fe2O4 with the crystal structure and lattice parameter of Fd3m and 0.84124 nm, respectively. Microstructure observation and chemical analysis by transmission electron microscopy and energy-dispersive spectroscopy respectively showed that nanosized nickel-zinc ferrite particles with a diameter of about 20 nm exist in the thin composite nickel sheet. Maximum magnetization (M-s), residual magnetization (M-r), and coercive force (H-i(c)) were 7.75 Wb/m(2)/kg, 0.88 m(3)/kg, and 1297 A/m, respectively. The complex permeability decreases with an increase in frequency, and its real value (mu(')(r)) has an maximum at about 0.65 GHz. (C) 2011 The Japan Society of Applied Physics