Development of magneto-dielectric materials based on Li-ferrite ceramics
| Autor: | M.L.S. Teo, Zheng-Wen Li, Ling Bing Kong, G.Q. Lin, Yeow-Beng Gan |
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| Rok vydání: | 2008 |
| Předmět: |
Permittivity
Materials science Analytical chemistry Sintering Relative permittivity Mineralogy Dielectric Nuclear magnetic resonance Electrical resistivity and conductivity Materials Chemistry Ceramic Composite material Mechanical Engineering Metals and Alloys Magnetocrystalline anisotropy Microstructure Grain growth Magnetic anisotropy Permeability (electromagnetism) Mechanics of Materials visual_art Melting point visual_art.visual_art_medium Ferrite (magnet) Dielectric loss Relative permeability |
| Zdroj: | Journal of Alloys and Compounds. 459:567-575 |
| ISSN: | 0925-8388 |
| Popis: | This paper reports on the effects of Bi 2 O 3 and Co on the magnetic properties of Li 0.50 Fe 2.50 O 4 ceramics. The magnetic properties (static permeability) of the lithium ferrite ceramics with low concentration of Bi 2 O 3 (0.2% and 0.5%), as a function of sintering temperature, can be explained by the magnetic circuit model, while those of the samples with high concentration (1–5%) are in a good agreement with the Globus model. Both models are not applicable to the results of pure Li 0.50 Fe 2.50 O 4 samples, because their magnetic properties are determined by both the density and grain size. Further modification of Li 0.50 Fe 2.50 O 4 with Co makes it possible to produce ferrite ceramics with promising magneto-dielectric properties. Maximum static permeability is observed in Li 0.50–0.50 x Co x Fe 2.50–0.50 x O 4 at x = 0.01, which can be qualitatively explained by magnetocrystalline anisotropy and ion ordering induced local uniaxial anisotropy. It is found that the Li 0.50–0.50 x Co x Fe 2.50–0.50 x O 4 (with x = 0.030–0.035) ceramics sintered at ≤950 °C have matching permeability and permittivity of 13–15, as well as sufficiently low magnetic and dielectric loss tangents of ≤10 −2 , over 3–30 MHz (HF band). From the laws of physics, HF antennas can be physically reduced by a factor of 13–15, with unchanged electrical dimension, if loaded with this class of magneto-dielectric materials. |
| Databáze: | OpenAIRE |
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