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RISS 인기검색어
- 검색키워드
- 저자 : Anterpreet Singh (검색결과 2 건)
- 무료
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Electrical and magnetic properties of rare earth substituted strontium hexaferrites
Anterpreet Singh,S. Bindra Narang,Kulwant Singh Thind,O.P. Pandey,R.K. Kotnala 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.2
Samples of strontium ferrite (Sr-M) with different molar substitution concentrations of lanthanum, neodymium and samarium ions were prepared by a standard ceramic processing technique. AC conductivity, dielectric constant and dielectric loss tangent measurements were carried out in the frequency range of 20 Hz to 1MHz. The experimental results indicate that AC electrical conductivity increases with increasing frequency. The increase in AC conductivity with frequency can be explained on the basis of Koops model, whereas the dielectric constant and dielectric loss tangent variations have been explained with a Maxwell-Wagner type interfacial polarization in agreement with the Koops phenomenological theory. The effects of rare earth substitution on the magnetic properties such as the saturation magnetization moment (Ms), coercive field (Hc), remenance (Mr),and Curie temperature Tc (K) have been investigated. It is found that the values of the magnetization moment (Ms), and remenance (Mr) decrease with increasing rare earth ions substitution for all the series. The reason for the decrease may be both the magnetic dilution and spin canting, which promote reduction of superexchange interactions. The enhancement of Hc values may be due to higher magnetocrystalline anisotropy, where Fe2+ ion anisotropy on the 2a site could be dominant in all hexaferrites series.
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High Frequency Dielectric Behavior of Rare Earth Substituted Sr-M Hexaferrite
S. Bindra Narang,Anterpreet Singh,Kulwant Singh 한양대학교 세라믹연구소 2007 Journal of Ceramic Processing Research Vol.8 No.5
Strontium hexaferrites of a structural formula Sr1-xRExFe12O19, where RE=La3+, Nd3+ and Sm3+ with (x=0 to 0.30) were prepared by a standard ceramic technique. The lattice constants, density, porosity, dielectric constant and dielectric loss tangent were studied on a series of rare earth substituted strontium hexaferrites. The dielectric constant and dielectric loss tangent were measured in the frequency range of 0.3 GHz to 3.0 GHz at room temperature. The dielectric constant decreased with increasing frequency for all the three series. This behavior of dielectric properties with frequency has been explained with the Maxwell-Wagner type interfacial polarization in agreement with the Koops phenomenological theory. The substitution of rare earth ions into SrFe12O19 increases the value of the dielectric constant. This increase in dielectric constant could be due to the electronic exchange between Fe2+ ↔ Fe3+ and results in a local displacement determining the polarization of the ferrites. For these ferrite samples the Curie temperature decreases as rare earth ions substitution increases. Strontium hexaferrites of a structural formula Sr1-xRExFe12O19, where RE=La3+, Nd3+ and Sm3+ with (x=0 to 0.30) were prepared by a standard ceramic technique. The lattice constants, density, porosity, dielectric constant and dielectric loss tangent were studied on a series of rare earth substituted strontium hexaferrites. The dielectric constant and dielectric loss tangent were measured in the frequency range of 0.3 GHz to 3.0 GHz at room temperature. The dielectric constant decreased with increasing frequency for all the three series. This behavior of dielectric properties with frequency has been explained with the Maxwell-Wagner type interfacial polarization in agreement with the Koops phenomenological theory. The substitution of rare earth ions into SrFe12O19 increases the value of the dielectric constant. This increase in dielectric constant could be due to the electronic exchange between Fe2+ ↔ Fe3+ and results in a local displacement determining the polarization of the ferrites. For these ferrite samples the Curie temperature decreases as rare earth ions substitution increases.
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