Synthesis and gyromagnetic properties of highly-dense LiZnTi ferrite for microwave ferrite devices

Abstract

LiZnTi ferrites with dense microstructure and excellent gyromagnetic properties are a critical class of materials for microwave ferrite devices. Many reported studies have demonstrated that grain refinement and good gyromagnetic properties is often contradictory. In this work, we have successfully prepared a highly-dense LiZnTi ferrite with small average grain size (<1.0μm) and good gyromagnetic properties by hot-pressure sintering (HPS) method. Interestingly, SEM images revealed that the hot-pressure sintering with zero holding time not only promoted densification of the LiZnTi ferrites, but also can realize their grain refinement, which effectively reduced porosity and improved gyromagnetic properties. Meanwhile, we found that the average grains size (GSave.) of the HPS950 sample is smaller than the TS950 and HPS900 samples due to the synergistic effect of applied pressure (zero holding time) and Bi2O3 liquid phase. Finally, a LiZnTi ferrite with uniform, dense grains (GSave. = 0.85 μm and ρr = 98.1 %) and good gyromagnetic properties (4πMs = 3859.6Gs and ΔH = 287.4 Oe) was obtained by hot-pressure sintering at ∼950 °C.