Structure Analysis and Magnetic Properties of Nano-Sized Nb<SUB><I>x</I></SUB>Cu<SUB><I>y</I></SUB>Zn<SUB>1−<I>x</I>−<I>y</I></SUB>Fe<SUB>2</SUB>O<SUB>4</SUB> Powders Formed by Self-Propagating High-Temperature Synthesis and Ultrasonic Agitation Method

Abstract

Nano-sized Nb0.12Cu0.45Zn0.43Fe2O4 ferrites with an average size of the agglomerated particles less than 300 nm were prepared by self-propagating high-temperature synthesis (SHS) followed by mechanical ball milling and classifying by ultrasonic floating agitation. The SHS reaction occurred in the powder mixture of iron and various oxides like NbO, CuO, ZnO, Fe2O3 at the oxygen pressure range of 0.1 to 1.0 MPa, which average combustion temperatures and combustion propagating rates were in the ranges of 1105 to 1343 K and 4.1 to 6.2 mm/s, respectively. The combustion temperature increased with the oxygen pressure. The combustion reaction did not occur above the uniaxial compacting pressure of 10.0 MPa, even though the oxygen pressure was 1.0 MPa. The neutron diffraction analysis revealed that the final product was Nb0.12Cu0.45Zn0.43Fe2O4 with lattice parameters of 0.8472 nm. The maximum magnetization (Ms), residual magnetization (M(r)), coercive force (iH0), and susceptibility of the Nb0.12Cu0.45Zn0.43Fe2O4 ferrites were 11.30 Wb/m2 Kg, 1.47 Wb/m2 Kg, 7321 A/m, and 0.02 m3/kg, respectively. The addition of niobium to copper-zinc ferrites resulted in increasing M(s), M(r), and iM(c) by about 49%, 68%, and 287%, respectively. The variation of the magnetic properties is related to the non-stoichiometric numbers and oxygen position of the niobium-copper-zinc ferrites.