Chemical homogeneity, microstructure and magnetic properties of LiTiZn ferrite ceramics doped with Al2O3 or ZrO2

Abstract

Sintering of ferrite materials requires sensitive control of homogeneity that affects electromagnetic properties. The paper proposes a method for analysis of chemical homogeneity of ferrite ceramics based on mathematical analysis of differential temperature dependences of the initial permeability near the Curie point. The method was tested on model samples of LiTiZn ferrite ceramics doped with Al 2 O 3 or ZrO 2 of 0.10, 0.25, 0.5 0.75, and 1 wt%. It was found the effect of doping agents on the ferrite lattice parameter is insignificant, and they are not indicated on the diffraction patterns as separate peaks. SEM data show a weak effect of Al 2 O 3 doping agent on the average grain size of ferrite ceramics. At the same time, the effect is more pronounced for ZrO 2 due to secondary recrystallization. In this case, the coercive force shows a particular increase as compared with undoped samples: by 23% and 60% for Al 2 O 3 and ZrO 2 respectively of doping agents’ concentration increased to 1 wt%. The paramagnetic-to-ferrimagnetic transition of ferrites near the Curie point is highly sensitive to chemical homogeneity of the material. It was shown that the width of the differential temperature dependence peak of the initial permeability can be used to assess chemical homogeneity of ferrimagnetic ceramics. The peak width was found to increase by 75%. Therefore, the proposed method revealed a higher sensitivity compared to XRD and hysteresis loops. • The study revealed the effect of doping agents Al 2 O 3 or ZrO 2 on microstructural and magnetic properties of LiTiZn ferrites. • The paramagnetic transition of ferrites is characterized by the rate of the decrease in the initial permeability. • The transition highly sensitive to chemical homogeneity of LiTiZn ferrite ceramics. • A highly sensitive method has been developed for analysis of chemical homogeneity. • A decrease in the peak width is the most sensitive characteristic of chemical homogeneity increases.