No abstract

The sintering behavior and high frequency electro-magnetic properties of Ba3Co2Fe24O41ceramics were investigated for the small antenna application. All samples of the Ba3Co2Fe24O41ceramics were prepared by the solid-state reaction method and sintered at 1150°C 1400°C. From the XRD patterns of calcined Ba3Co2Fe24O41powders, the most suitable condition for calcining was 600°C–1000°C. Ba3Co2Fe24O41phase was observed in sintered Ba3Co2Fe24O41ceramics as main phase. Bulk densities increased with sintering temperature and decreased at 1400°C. Permittivity and permeability of the Ba3Co2Fe24O41ceramics increased or decreased with sintering temperature, respectively. On the other hand, loss tangent of permittivity and of permeability showed contrary tendency with permittivity and permeability. The permittivity and loss tangent of permittivity of Ba3Co2Fe24O41ceramics sintered at 1300°C were 19.896 and 0.171 at 210 MHz. and the measured value of permeability and loss tangent of permeability were 14.218 and 0.204, respectively.

No abstract

No abstract

Ba(Mg,Ta)03-Ba(Co,Nb)03 ceramics were prepared by the conventional mixed oxide method. The ceramics were sintered at the temperature of 1500 -1575 "C for 5 hours in air.Ba(Mg,Ta)0,-Ba(Co,Nb)03 ceramics have a structure of complex perovskite type, and have peaks of (101),(102),(201),(202) and (212).In the case of the 0.7Ba(Mg,Ta)03-0.3Ba(Co,Nb)03 specimens sintered at 1550°C for 5 hours, dielectric constant, quality factor and temperature coefficient of resonant fiequency(TCRF, z, ) were a good value of 27, 15,712 at 11 Glfz and -1.3 PPM/"C from 25°C to 60"C, respectively. structure of ABO, have excellent dielectric properties, especially the high Q performance. However further modification is needed on the basis of performance improvement, cost reduction, and especially the lower sintering temperature.Therefore, in this study, the dielectric characteristics of the Ba(Mg%Tax)O~-Ba(Co%Nbx)O,[BMT-BCN]ceramics were developed to lower the sintering temperature and to improve the microwave Q-value and zf. The effects of the sintering temperature on the composition of BMT-BCN were investigated. The influences of various compositions and sintering temperatures on the system were studied Also the application for the dielectiic resonator was studied.