Low-temperature sintering and microwave dielectric properties of 5Li2O–0.58Nb2O5–3.23TiO2 ceramics

The effect of B2O3 addition on the sintering, microstructure and the microwave dielectric properties of the 5Li2O–0.58Nb2O5–3.23TiO2 (LNT) ceramics have been investigated. It is found that the LNT ceramics could be sintered well at ∼880 °C with low-level doping of B2O3 (≤2 wt.%). Only Li2TiO3 solid solution (Li2TiO3ss) crystal structure could be detected for all the ceramics with various amounts of B2O3 addition from the X-ray diffraction (XRD) results. And interestingly, two phases with different color in SEM images are observed in B2O3-doped LNT ceramics. EDS results suggest that the two different phases are two Li2TiO3ss phases with different amount of Nb. In addition, there is no much degradation in the microwave dielectric properties with the B2O3 adding. In the case of 0.5 wt.% B2O3-doped samples sintered at 880 °C, good microwave dielectric properties of ɛr = 22, Q × f = 32,000 GHz, τf = 9.5 ppm °C−1 are obtained.

► The 5Li2O-0.58Nb2O5-3.23TiO2 (LNT) ceramics with B2O3 could be well sintered at lower than 900 °C.
► Two Li2TiO3 solid solution phases with different amount of Nb are observed in the ceramics.
► Good microwave dielectric properties of ɛr = 22, Q × f = 32,000 GHz, τf = 9.5 ppm °C−1 are obtained for the 0.5 wt.% B2O3 doped samples.
► The LNT ceramics could be suitable candidates as low temperature co-fired ceramics.