Li₂MoO₄-based composite ceramics fabricated from temperature- and atmosphere-sensitive MnZn ferrite at room temperature

Abstract

<div lang="en" class="abs"><p class="abs_header">Abstract</p><p>The first magnetic ceramic composites manufactured, using the room-temperature densification method are reported. The samples were prepared at room temperature using Li₂MoO₄ as a matrix and MnZn ferrite with loading levels of 10–30 vol-% followed by postprocessing at 120°C. The method utilizes the water solubility of the dielectric Li₂MoO₄ and compression pressure instead of high temperatures typical of conventional solid-state sintering. Hence, composite manufacturing using temperature- and atmosphere-sensitive materials is possible without special conditions. This was demonstrated with MnZn ferrite, which is prone to oxidation when heat treated in air. Samples manufactured with room-temperature densification showed no signs of reactivity during processing, whereas reference samples sintered at 685°C suffered from oxidation and formation of an additional reaction phase. The densities achieved with different loading levels of MnZn ferrite with both methods were very similar. Measurements up to 1 GHz showed relatively high values of relative permittivity (21.7 at 1 GHz) and permeability (2.6 at 1 GHz) with 30 vol-% loading of MnZn ferrite in the samples manufactured by room-temperature densification. In addition, pre-granulation is proposed to improve the processability of the composite powders in room-temperature densification.</p></div>