BaFe12O19 hexaferrites were prepared by citrate sol-gel process. The formation temperature was much lower than that of the conventional ceramic method. The complex dielectric constant and complex permeability of hexaf...BaFe12O19 hexaferrites were prepared by citrate sol-gel process. The formation temperature was much lower than that of the conventional ceramic method. The complex dielectric constant and complex permeability of hexaferrite-paraffin wax composites had been measured by the transmission/reflection coaxial line method in the range from 200 MHz to 6 GHz. The measurement results showed that both the complex dielectric constant and dielectric loss exhibited no significant variation with the measuring frequency increase. It also showed that the real part of permeability decreased as the frequency increasing for all samples, the resonance phenomena due to domain wall resonance was observed in ?' spectra, the calcining temperature strongly affects the microwave properties of BaFe12O19 ferrites, the higher the calcining temperature, the lower the resonance frequency.展开更多
s Ba_4Zn_zCo_(2-z)Fe_(36)O_(60) hexaferrites with Z = 2.0, 1.5, 1.0, 0.5, and0.0 were prepared by a citrate Sol-gel process. The complex dielectric constant and complexpermeability of hexaferrite-paraffin wax composit...s Ba_4Zn_zCo_(2-z)Fe_(36)O_(60) hexaferrites with Z = 2.0, 1.5, 1.0, 0.5, and0.0 were prepared by a citrate Sol-gel process. The complex dielectric constant and complexpermeability of hexaferrite-paraffin wax composites were measured in the range from 0.1 to 6.0 GHz.Measured results showed that both the complex dielectric constant and the dielectric loss exhibitedno significant change as the measuring frequency increasing except for the sample with Z = 0.0. Thereal part of permeability decreased with increasing frequency for all samples in the whole measuringfrequency range, and the natural resonance phenomena were observed in all μ″ spectrum but Co_2U.The results also indicate that the content of zinc closely affects the microwave properties ofBa_4Zn_zCo_(2-z)Fe_(36)O_(60) ferrites, and the greater the zinc content, the lower the naturalresonance frequency is.展开更多
Based on thermodynamic analysis,O'-Sialon-SiC-ZrO2 composites have been prepared by carbonthermal reduction-nitriation from natural kaolin and zircon with certain additives,The modulus of racture of well sintere...Based on thermodynamic analysis,O'-Sialon-SiC-ZrO2 composites have been prepared by carbonthermal reduction-nitriation from natural kaolin and zircon with certain additives,The modulus of racture of well sintered specimen may reach 110 MPa,The process of reaction-sintering has been discussed,The formation temperature of O'-Sialon is 1718 K by calcuation.展开更多
基金This project is financially supported by the National Natural Science Foundation of China (No.59995320.4)
文摘BaFe12O19 hexaferrites were prepared by citrate sol-gel process. The formation temperature was much lower than that of the conventional ceramic method. The complex dielectric constant and complex permeability of hexaferrite-paraffin wax composites had been measured by the transmission/reflection coaxial line method in the range from 200 MHz to 6 GHz. The measurement results showed that both the complex dielectric constant and dielectric loss exhibited no significant variation with the measuring frequency increase. It also showed that the real part of permeability decreased as the frequency increasing for all samples, the resonance phenomena due to domain wall resonance was observed in ?' spectra, the calcining temperature strongly affects the microwave properties of BaFe12O19 ferrites, the higher the calcining temperature, the lower the resonance frequency.
基金This work was financially supported by the National Natural Science Foundation of China (No. 59995320.4).
文摘s Ba_4Zn_zCo_(2-z)Fe_(36)O_(60) hexaferrites with Z = 2.0, 1.5, 1.0, 0.5, and0.0 were prepared by a citrate Sol-gel process. The complex dielectric constant and complexpermeability of hexaferrite-paraffin wax composites were measured in the range from 0.1 to 6.0 GHz.Measured results showed that both the complex dielectric constant and the dielectric loss exhibitedno significant change as the measuring frequency increasing except for the sample with Z = 0.0. Thereal part of permeability decreased with increasing frequency for all samples in the whole measuringfrequency range, and the natural resonance phenomena were observed in all μ″ spectrum but Co_2U.The results also indicate that the content of zinc closely affects the microwave properties ofBa_4Zn_zCo_(2-z)Fe_(36)O_(60) ferrites, and the greater the zinc content, the lower the naturalresonance frequency is.
文摘Based on thermodynamic analysis,O'-Sialon-SiC-ZrO2 composites have been prepared by carbonthermal reduction-nitriation from natural kaolin and zircon with certain additives,The modulus of racture of well sintered specimen may reach 110 MPa,The process of reaction-sintering has been discussed,The formation temperature of O'-Sialon is 1718 K by calcuation.
