Title: Preparation, thermal stability and permeability behaviour of Z-type hexagonal ferrites for multilayer inductors

Authors: Silvia Kracunovska, Jorg Topfer

Addresses: Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07745 Jena, Germany. ' Department of SciTec, University of Applied Sciences Jena, Carl-Zeiss-Promenade 2, 07745 Jena, Germany

Abstract: Co2Z hexaferrite Ba3Co2Fe24O41 with iron excess Ba3Co2−xFe24+xO41 (0 ≤ x ≤ 0.8) and deficiency Ba3Co2+yFe24−yO41 (0 ≤ y ≤ 0.6) were prepared by a mixed oxalate co-precipitation route and the standard ceramic technology. XRD studies showed that both synthesis routes lead to an almost single phase Z-type ferrites for x = 0 after calcination and sintering at 1330°C. For iron deficient samples, 0 ≤ y ≤ 0.6, the multi-phase mixtures were observed. The permeability of Z-type ferrites varied with composition x. The maximum permeability of μ| = 37 was observed for the sample with x = 0.6. Addition of Bi2O3 as sintering aid shifts the temperature of maximum shrinkage to lower temperatures and dense samples were obtained after sintering at 950°C. However, the permeability is only μ| = 3. It is shown here that Co2Z ferrites are not stable under 1300°C and that partial thermal decomposition causes a reduction of the permeability.

Keywords: soft ferrites; Co2Z hexagonal ferrites; thermal stability; permeability; soft magnetic materials.

DOI: 10.1504/IJMPT.2011.037204

International Journal of Materials and Product Technology, 2011 Vol.40 No.1/2, pp.15 - 35

Published online: 28 Feb 2015 *

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