Development of magneto-dielectric materials based on Li-ferrite ceramics
DC resistivity and dielectric properties of the Li-ferrite ceramics (Li 0.50Fe 2.50O 4) doped with Bi 2O 3 (0–5 wt%) and modified with Co (Li 0.50−0.50 x Co x Fe 2.50−0.50 x O 4, with x = 0.01–0.07) were investigated, with a primary objective to develop magneto-dielectric materials with matching per...
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Published in | Journal of alloys and compounds Vol. 459; no. 1; pp. 567 - 575 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Elsevier B.V
01.07.2008
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Subjects | |
Online Access | Get full text |
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Summary: | DC resistivity and dielectric properties of the Li-ferrite ceramics (Li
0.50Fe
2.50O
4) doped with Bi
2O
3 (0–5
wt%) and modified with Co (Li
0.50−0.50
x
Co
x
Fe
2.50−0.50
x
O
4, with
x
=
0.01–0.07) were investigated, with a primary objective to develop magneto-dielectric materials with matching permeability and permittivity and low magnetic and dielectric loss tangent, for miniaturization of HF antennas. It is impossible to obtain pure Li
0.50Fe
2.50O
4 ceramics with low dielectric loss tangent because it cannot be sintered at temperature of ≤1100
°C and high temperature sintering will lead the formation Fe
2+ ions. Although 1% Bi
2O
3 is sufficient to obtain fully dense Li
0.50Fe
2.50O
4 ceramics over 850–1100
°C, it is insufficient to produce materials with a dielectric loss tangent of ≤10
−2. A high concentration (3%) Bi
2O
3, combined with sintering temperature of ≤950
°C, is required to attain sufficiently low dielectric loss tangent of ≤10
−2 over the frequency range of interest (3–30
MHz or HF band). The variation of relative permittivity and dielectric loss tangent of the Li
0.50Fe
2.50O
4 ceramics as a function of the concentration of Bi
2O
3 and sintering temperature can be understood in terms of the microstructure developed. It is also found that the effect of Co on the dielectric properties of Li
0.50Fe
2.50O
4 ceramics is much less than that of Bi
2O
3. |
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ISSN: | 0925-8388 1873-4669 |
DOI: | 10.1016/j.jallcom.2007.05.082 |