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A glass/ceramic composite using lead-free low melting glass (SiO2B2O3CaOMgO glass) with Al2O3 fillers was investigated. X-ray diffraction analysis revealed that the anorthite and cordierite phase appeared in the sintered composites. The dilatometric analysis showed that the onset of shrinkage took place at ∼624°C for all the samples and the onset temperature was independent on the content of glass. The low melting glass significantly promoted densification of the composites and lowered the sintering temperature to ∼875°C. The addition of 50wt% glass sintered at 875°C showed ε r of 7.3, tan δ of 1.15×10−3, TEC of 5.41ppm/°C, thermal conductivity of 3.56W/m°C, and flexural strength of 184MPa. The results showed that the SiO2B2O3CaOMgO glass/Al2O3 composites were strong potential candidates for low temperature cofired ceramic substrate applications. [ABSTRACT FROM AUTHOR]

Abstract: The effects of Bi4B2O9 on the phase transitions, sinterability and microwave dielectric properties of Bi3NbO7 ceramics were investigated. Densities around 96% theoretical could be achieved at 900°C for samples with up to 20wt% Bi4B2O9 addition. Phase transitions of cubic→tetragonal→cubic with the increase of sintering temperature were observed for the samples with Bi4B2O9 addition. Moreover, the Bi4B2O9 addition effectively accelerated the phase transition from cubic Bi3NbO7 to tetragonal Bi3NbO7. Bi4B2O9 addition and the sintering temperature significantly affected the microwave dielectric properties mainly due to the phase transitions. When 20wt% Bi4B2O9 was added, a dense ceramic could be sintered at 900°C with relative permittivity ε r=79, microwave quality factor Qf 0=1010GHz, and temperature coefficient of resonance frequency τ f=+8ppm/°C, which makes it a promising candidate for LTCC applications. [Copyright &y& Elsevier]