Li₂MoO₄-based composite ceramics fabricated from temperature- and atmosphere-sensitive MnZn ferrite at room temperature
Väätäjä, Maria; Kähäri, Hanna; Juuti, Jari; Jantunen, Heli (2017-04-27)
Väätäjä M, Kähäri H, Juuti J, Jantunen H. Li2MoO4-based composite ceramics fabricated from temperature- and atmosphere-sensitive MnZn ferrite at room temperature. J Am Ceram Soc. 2017;00:1–10. https://doi.org/10.1111/jace.14914
© 2017 The American Ceramic Society. This is the peer reviewed version of the following article: Väätäjä M, Kähäri H, Juuti J, Jantunen H. Li2MoO4-based composite ceramics fabricated from temperature- and atmosphere-sensitive MnZn ferrite at room temperature. J Am Ceram Soc. 2017;00:1–10. https://doi.org/10.1111/jace.14914, which has been published in final form at https://doi.org/10.1111/jace.14914. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
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.
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