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Item type:Publication, Access status: without files , Sintering, microwave properties, and circulator applications of textured Sc-substituted M-type ferrite thick filmsSc 3+ substituted M-type ferrites are effective microwave magnetic materials with a ferromagnetic resonance frequency in the range of 20 GHz–50 GHz. We report on the fabrication of oriented ferrite thick films as microwave components for application in the K a -band at 30 GHz. Films of BaFe 11.5. Sc 0.5 O 19 were prepared by screen-printing on alumina substrates, drying in an external magnetic field, and sintering at 900 °C. Low-temperature sintering is achieved through use of a mixed BBSZ/CuO sintering aid. A strong anisotropy of the sintered ferrite films is revealed by XRD analysis. Microwave properties of the films were determined in a coplanar waveguide setup. The ferromagnetic resonance frequency of the films is at 30 GHz and the textured films possess good nonreciprocal properties which scale with film thickness. The films were tested in a Y-junction circulator, and represent promising materials for self-biased microwave components fabricated in thick film technology.Publicationtype: Journal Article475 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Low-temperature sintering and magnetic properties of Sc- and In-substituted M-type hexagonal barium ferrites for microwave applicationsPartial substitution of Fe3+ by Sc3+ or In3+ in M-type ferrite is an effective method to tailor their anisotropy field and resonance frequency. BaMexFe12-xO19 with Me = Sc and In (0 ≤ x ≤ 2) was synthesized by the mixed-oxide route. XRD revealed a continuous increase of the hexagonal lattice parameters with substitution rate x. Both, the saturation magnetization and coercivity at room temperature are reduced with x. The ferromagnetic resonance frequency decreases from 48 GHz at x = 0 to 30 GHz at x = 0.5 for Sc-substituted ferrites. For In-substitution, a smaller reduction of the resonance frequency with x is observed, e.g. to 37 GHz at x = 0.5. Addition of BBSZ glass allows sintering at 900 °C. Low-temperature fired samples exhibit ferromagnetic resonance at the same frequencies and represent promising materials for self-biased microwave components for integration into LTCC multilayer modules.Publicationtype: Journal Article75