Low-temperature sintering and dielectric properties of high-permittivity microwave (Ca, Nd)TiO3 ceramics

The effect of H3BO3–CuO–Li2CO3 combined additives on the sintering temperature, microstructure and microwave dielectric properties of (Ca0.61Nd0.26) (Ti0.98Sn0.02)O3 (CNTS) ceramics was investigated. The H3BO3–CuO–Li2CO3 combined additives lowered the sintering temperature of CNTS ceramics effectively from 1300 to 950 °C. This may be due to the interim liquid-phase of Li2O–CuO–B2O3, which were formed in the sintering process. (Li0.5Nd0.5)TiO3 (LNT) demonstrated an effective compensation in τf value of the low-fired CNTS ceramics. The 0.4CNTS–0.6LNT ceramics with 5 wt% (H3BO3–CuO)–0.5 wt% Li2CO3 sintered at 900 °C for 2 h shows excellent dielectric properties: ɛr = 90.6, Q × f = 3400 GHz, and τf = 9 ppm/°C. Also, the LTCC material is compatible with Ag electrode.

► The H3BO3–CuO–Li2CO3 combined additives lowered the sintering temperature of CNTS ceramics effectively from 1300 to 950 °C. This may be due to the interim liquid-phase of Li2O–CuO–B2O3, which were formed in the sintering process.
► (Li0.5Nd0.5)TiO3 (LNT) demonstrated an effective compensation in τf value of the low-fired CNTS ceramics. The 0.4CNTS–0.6LNT ceramics with 5 wt% (H3BO3–CuO)–0.5 wt% Li2CO3 sintered at 900 °C for 2 h shows excellent dielectric properties: ɛr = 90.6, Q × f = 3400 GHz, and τf = 9 ppm/°C.
► The dielectric ceramics is compatible with Ag electrodes and, therefore, is suitable for LTCC application.