Compositions of MgTiO3–CaTiO3 ceramic with two borosilicate glasses for LTCC technology

Mixtures of ZnO–SiO2–B2O3/MgTiO3–CaTiO3 (ZSB/MMT-20) and BaO–SiO2–B2O3/MgTiO3–CaTiO3 (BSB/MMT-20) have been investigated as new candidates for LTCC dielectric materials. Two-stage sintering behaviour was observed in both materials, starting at around 600 and 850°C. Nearly full density (97%) was achieved in ZSB/MMT-20 after sintering at 900°C, while a high porosity of 23% was measured in BSB/MMT-20 after firing at 875°C followed by partial melting of samples during sintering at 900°C. After firing, fully crystalline structure with phases of ZnTiO3, Zn2SiO4, Mg4/3Zn2/3B2O5 and TiO2 were found in ZSB/MMT-20, while the structure of BSB/MMT-20 consisted of crystalline TiO2 and BaTi(BO3)2 and amorphous SiBa(BO3)2 and SiB2O5. ZSB/MMT-20 fired at 900oC showed promising microwave properties having the dissipation factor of 0.001 and a permittivity of 10.6 at 7 GHz. The corresponding values for BSB/MMT-20 fired at 875°C were 0.002 and 8.2, respectively.