Effect of sintering regimes on the microstructure and magnetic properties of LiTiZn ferrite ceramics

Abstract

In present work, the influence of sintering regimes on the microstructure, saturation magnetization, density and porosity, the grain size, the Curie point, and the temperature dependence of the initial permeability of LiTiZn ferrite ceramics was investigated. Ceramics was prepared by a standard ceramic technique. The formation of a single-phase cubic spinel structure was confirmed by XRD analysis. The Curie point was determined from both the temperature dependences of the initial permeability and the method of thermogravimetric measurements in a magnetic field. Density/porosity and the grain size, the Curie point and magnetization are sensitive to the sintering regime. The initial permeability of ferrite decreases with sintering temperature (in the range of 1010–1150 °С) and grain size increasing that contradicts the generally accepted Globus and Smith-Wijn theories. A possible reason of such behavior is the formation of intragranular pores growing with the increase in the sintering temperature and inhibiting the domain wall motion inside the grain. These results correspond to the porosity of the investigated ferrite ceramic samples, which grows with sintering temperature increasing.The non-stoichiometry arising due to evaporation of lithium and zinc oxides at temperature above 1010 °C affects the initial permeability. In this work, a qualitative assessment of the defective state of ferrite samples obtained under various sintering regimes was given.