BaO-Sm_(2)O_(3)-4TiO_(2) 세라믹스의 저융점 소결조제 첨가에 따른 소결 거동 및 마이크로파 유전특성
Sintering behavior and microwave dielectric property of BaO-Sm_(2)O_(3)-4TiO_(2) ceramics with B_(2)O_(3) and BaB_(2)O_(4) addition
BaO-Sm_(2)O_(3)-4TiO_(2) 세라믹스 저융점 소결조제;
- 원문 URL
Low temperature co-fired ceramics possessing good microwave dielectric properties have recently been widely investigated, due to the necessity for miniaturization of microwave devices to reduce the size of wireless communication system. However, the microwave dielectric materials, which possess high quality factor and large dielectric constant, usually need very high sintering temperature and long soaking time to achieve high enough density. On the other hand, using the Ag material as conducting materials for transmission lines and ground planes is needed in order to minimize the microwave absorption loss. Reduction on the sintering temperature for the microwave material to a level cofirable with Ag-electrode(m.p.≒961℃) or Cu-electrode(m.p.≒1083℃)materials is thus called for, which can be achieved by mixing the low softening temperature glass materials with the ceramic materials. In this study, interaction of between ceramic and glass, phase transition, and microwave dielectric properties in systems BaO-Sm_(2)O_(3)-4TiO_(2) and addition of B_(2)O_(3) and BaB_(2)O_(4) were investigated. BaO-Sm_(2)O_(3)-4TiO_(2) were calcined at 1250℃ for 2 hours and gained single phase BaSm_(2)Ti_(4)O_(12). When B_(2)O_(3) was added, second phases of TiO_(2), Sm_(2)Ti_(2)O_(7), B_(2)O_(3), BaTi(BO_(3))_(2), etc. were formed. Each composition has its own specific densification temperature range. The highest density of 1wt% addition composition is 5.51g/㎤ at 1300℃. Grain growth was observed with increasing B_(2)O_(3) content from 1 to 10wt.% The relative permittivity value(εr) increased from 25 to 37.9 with increasing sintering temperature. The quality factor decreased with increasing addition from 1wt% to 10wt%. As TiO_(2) has high τ_(f) value of +450ppm/℃, the τ_(f) value of the sample, containing TiO_(2) as a second phase, shows a little increasing. BaB_(2)O_(4) addition resulted in the formation of BaSm_(2)Ti_(4)O_(12) single phase without second phases. The density increased with increasing sintering temperature and addition. Too high a sintering temperature causes the densities of the sintered ceramics to decrease. The highest density of 1wt% addition composition is 5.597g/㎤ at 1350℃. Grain growth was not observed. The relative permittivity value(ε_(r)) increased from 27 to 37.8 with increasing sintering temperature. The quality factor decreased with increasing sintering temperature.