CIP （complex initial permeability） spectra of PF （polycrystalline ferrite） are studied both as intrinsic and extrinsic properties. In the former case, main steps of modeling, based on effects coming from polycryst...CIP （complex initial permeability） spectra of PF （polycrystalline ferrite） are studied both as intrinsic and extrinsic properties. In the former case, main steps of modeling, based on effects coming from polycrystal grain sizes distribution and defects, are described. The obtained relations work well in practice for PF with more or less normal MS （microstructure） and no size effects. Besides, fundamental connection between parameters of CIP and MS is found. Another case--PF with possible size effects （MnZn-ferrites） are studied experimentally for different sizes of cores, unveiling the dependence of phenomena on： dimensions of cross-section, number of turns, width of nonmagnetic gap.展开更多
Polycrystalline xBa<sub>0.95</sub>Sr<sub>0.05</sub>TiO<sub>3</sub>-(1 - x)BiFe<sub>0.90</sub>Gd<sub>0.10</sub>O<sub>3</sub> ceramics were prepare...Polycrystalline xBa<sub>0.95</sub>Sr<sub>0.05</sub>TiO<sub>3</sub>-(1 - x)BiFe<sub>0.90</sub>Gd<sub>0.10</sub>O<sub>3</sub> ceramics were prepared by standard solid state reaction technique using the solid solution of BaCO<sub>3</sub>, SrCO<sub>3</sub>, TiO<sub>2</sub>, Bi<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub> and Gd<sub>2</sub>O<sub>3</sub>. The compound is a BiFeO<sub>3</sub> based multiferroic material which contains both magnetic and electric properties. The synthesized ceramics noticed better properties than xBaTiO<sub>3</sub>-(1 - x)BiFeO<sub>3</sub> because of adding rare earth element Gd which have higher magnetic moment than Fe. The prepared samples were sintered at 900<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C, 950<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C and 1000<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C for 1 h. The effect of sintering temperature on density of the compound, complex initial permeability, dielectric properties and complex impedance analysis was reported in this article. Density of the ceramics was found to be enhanced with the rise in sintering temperature which implied porosity of the compound decreased when sintering temperature was increased. Enhanced complex initial permeability was noticed for the samples up to 950<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C and this might be attributed to reducing the motion of domain wall when the ceramics were sintered above 950<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C. Value of dielectric constant increased whereas dielectric loss decreased and these modifications might be expected because of changing density and grain size due to the variation of sintering temperature. Grain resistance (resistance due to grains) was determined from complex impedance analysis and it reduced with the rise in sintering temperature. The studied multiferroic material exhibited weak ferromagnetism but is an alternative product of environmental hazard lead (Pb) based multiferroic material and it is expected to be environment friendly.展开更多
The polycrystalline Li<em><sub>x</sub></em>Ni<sub>0.2</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em>...The polycrystalline Li<em><sub>x</sub></em>Ni<sub>0.2</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> and Li<em><sub>x</sub></em>Ni<sub>0.1</sub>Cu<sub>0.1</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> (<em>x</em> = 0.0, 0.1, 0.2, and 0.3) ferrites were synthesized by the standard solid-state reaction method. The compound was sintered at 1150<span style="font-size:12px;white-space:nowrap;">˚</span>C for 5 hours. The effect of Cu substitution and its impact on the crystal structure, microstructure, complex initial permeability and magnetization of the Ni-Zn ferrites were studied. The effect of Li<sup>+</sup> incorporation on the properties mentioned above was also investigated. X-ray diffraction patterns of the samples indicated a single cubic spinel structure for both the compound. No effect of Cu addition on crystal structure was observed. The density of the ferrites was found to be enhanced because of adding Li whereas the porosity of the samples decreased with the content of Li ions. The average value of grain size increased with the addition of Li content. The samples having Cu ions formed bigger size grains. Frequency-dependent complex initial permeability, loss tangent, and relative quality factor were studied at room temperature using an Impedance analyzer in the range of 100 Hz - 120 MHz regions. In the low-frequency region, the prepared samples exhibited a high value of permeability and after a certain frequency, the permeability falls. The value of permeability enhanced with the increase in Li whereas loss tangent was found to be reduced. The relative quality factor graphs described that the compound has excellent frequency stability up to a certain frequency which is suitable to be used in inductors, resistors, capacitors, etc. Initial permeability for Li<em><sub>x</sub></em>Ni<sub>0.1</sub>Cu<sub>0.1</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> ferrites was found high than Li<em><sub>x</sub></em>Ni<sub>0.2</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> which might be attributed to having bigger size grains of Cu containing samples because of easy movement of domain wall in bigger size grains. The values of saturation magnetization (<em>M</em><sub>s</sub>) were calculated for both compounds from M-H hysteresis loops and it enhanced with the increase in Li content which might be related to the modification of predominant exchange interactions between the cations. The Cu-containing compound exhibited higher values of saturation magnetization. The cation distribution reflects this increment because ferromagnetic Ni<sup>2+</sup> and paramagnetic Cu<sup>2+</sup> ions occupied in the B-sites and the diamagnetic Zn and paramagnetic Li occupied in the A-sites;therefore, net magnetic moments increased gradually. The studied materials might be used as an alternative to Pb-based compounds and would be environment friendly.展开更多
文摘CIP （complex initial permeability） spectra of PF （polycrystalline ferrite） are studied both as intrinsic and extrinsic properties. In the former case, main steps of modeling, based on effects coming from polycrystal grain sizes distribution and defects, are described. The obtained relations work well in practice for PF with more or less normal MS （microstructure） and no size effects. Besides, fundamental connection between parameters of CIP and MS is found. Another case--PF with possible size effects （MnZn-ferrites） are studied experimentally for different sizes of cores, unveiling the dependence of phenomena on： dimensions of cross-section, number of turns, width of nonmagnetic gap.
文摘Polycrystalline xBa<sub>0.95</sub>Sr<sub>0.05</sub>TiO<sub>3</sub>-(1 - x)BiFe<sub>0.90</sub>Gd<sub>0.10</sub>O<sub>3</sub> ceramics were prepared by standard solid state reaction technique using the solid solution of BaCO<sub>3</sub>, SrCO<sub>3</sub>, TiO<sub>2</sub>, Bi<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub> and Gd<sub>2</sub>O<sub>3</sub>. The compound is a BiFeO<sub>3</sub> based multiferroic material which contains both magnetic and electric properties. The synthesized ceramics noticed better properties than xBaTiO<sub>3</sub>-(1 - x)BiFeO<sub>3</sub> because of adding rare earth element Gd which have higher magnetic moment than Fe. The prepared samples were sintered at 900<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C, 950<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C and 1000<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C for 1 h. The effect of sintering temperature on density of the compound, complex initial permeability, dielectric properties and complex impedance analysis was reported in this article. Density of the ceramics was found to be enhanced with the rise in sintering temperature which implied porosity of the compound decreased when sintering temperature was increased. Enhanced complex initial permeability was noticed for the samples up to 950<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C and this might be attributed to reducing the motion of domain wall when the ceramics were sintered above 950<span style="font-size:12px;white-space:nowrap;"><span style="font-size:12px;white-space:nowrap;">˚</span></span>C. Value of dielectric constant increased whereas dielectric loss decreased and these modifications might be expected because of changing density and grain size due to the variation of sintering temperature. Grain resistance (resistance due to grains) was determined from complex impedance analysis and it reduced with the rise in sintering temperature. The studied multiferroic material exhibited weak ferromagnetism but is an alternative product of environmental hazard lead (Pb) based multiferroic material and it is expected to be environment friendly.
文摘The polycrystalline Li<em><sub>x</sub></em>Ni<sub>0.2</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> and Li<em><sub>x</sub></em>Ni<sub>0.1</sub>Cu<sub>0.1</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> (<em>x</em> = 0.0, 0.1, 0.2, and 0.3) ferrites were synthesized by the standard solid-state reaction method. The compound was sintered at 1150<span style="font-size:12px;white-space:nowrap;">˚</span>C for 5 hours. The effect of Cu substitution and its impact on the crystal structure, microstructure, complex initial permeability and magnetization of the Ni-Zn ferrites were studied. The effect of Li<sup>+</sup> incorporation on the properties mentioned above was also investigated. X-ray diffraction patterns of the samples indicated a single cubic spinel structure for both the compound. No effect of Cu addition on crystal structure was observed. The density of the ferrites was found to be enhanced because of adding Li whereas the porosity of the samples decreased with the content of Li ions. The average value of grain size increased with the addition of Li content. The samples having Cu ions formed bigger size grains. Frequency-dependent complex initial permeability, loss tangent, and relative quality factor were studied at room temperature using an Impedance analyzer in the range of 100 Hz - 120 MHz regions. In the low-frequency region, the prepared samples exhibited a high value of permeability and after a certain frequency, the permeability falls. The value of permeability enhanced with the increase in Li whereas loss tangent was found to be reduced. The relative quality factor graphs described that the compound has excellent frequency stability up to a certain frequency which is suitable to be used in inductors, resistors, capacitors, etc. Initial permeability for Li<em><sub>x</sub></em>Ni<sub>0.1</sub>Cu<sub>0.1</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> ferrites was found high than Li<em><sub>x</sub></em>Ni<sub>0.2</sub>Zn<sub>0.8-2</sub><em><sub>x</sub></em>Fe<em><sub>x</sub></em><sub>+2</sub>O<sub>4</sub> which might be attributed to having bigger size grains of Cu containing samples because of easy movement of domain wall in bigger size grains. The values of saturation magnetization (<em>M</em><sub>s</sub>) were calculated for both compounds from M-H hysteresis loops and it enhanced with the increase in Li content which might be related to the modification of predominant exchange interactions between the cations. The Cu-containing compound exhibited higher values of saturation magnetization. The cation distribution reflects this increment because ferromagnetic Ni<sup>2+</sup> and paramagnetic Cu<sup>2+</sup> ions occupied in the B-sites and the diamagnetic Zn and paramagnetic Li occupied in the A-sites;therefore, net magnetic moments increased gradually. The studied materials might be used as an alternative to Pb-based compounds and would be environment friendly.
