Novel medium-permittivity Ba2.92Cu0.08(Zn1/3Nb2/3)2Ti2Nb4O21 microwave dielectric ceramics with high Q × f value and densification for low-temperature co-fired ceramics electronic devices

With the emergence of 5G–6G communication technology, the miniaturization and integration of electronic components are crucial. Ba 3 Ti 4 Nb 4 O 21 (BTN) ceramics with hexagonal structures have attracted special attention due to their high dielectric constant, which shows greater application potential in communication base stations and dielectric resonators. However, its high sintering temperature and low-quality factors also greatly limit the application field. In this paper, boric acid (H 3 BO 3 ) as a dopant, was used to investigate the influence on the structure, microstructure, Raman spectrum, and microwave properties for Ba 2.92 Cu 0.08 (Zn 1/3 Nb 2/3 ) 2 Ti 2 Nb 4 O 21 (BCZTN)- x HB (0.25≤ x ≤1.25 wt%) ceramics. The results reflected that H 3 BO 3 was an effective additive, which could promote ceramic densification, accelerate grain growth and uniform distribution, and enhance its microwave performance. Among them, high densification was 93.92 ± 0.35%, and the Q × f value ∼16981 ± 340 GHz at x = 0.75, was more than 2∼3 times higher than other BTN-based ceramics. Superior microwave dielectric properties were achieved for 0.75 wt% H 3 BO 3 -doped BCZTN ceramic sintered at 900°C: ε r ∼42.35 ± 0.48, Q× f ∼16981 ± 340 GHz, and τ f ∼40.02 ± 1.43 ppm/°C. More encouragingly, BCZTN-0.75HB ceramic did not chemically react with Ag, which suggested that it had the potential to be a candidate material for low-temperature co-fired ceramics base station communication devices.