Deng Guangwen,Qing Zhenjun,Cheng Jiawen,Wang Jin,Zhao Yun,Li Haiyan
The solid-phase reaction method was adopted to prepare BaNi 2 V 2 O 8 ceramic with high relative density. The influences of the sintering process on the densification, microstructure, microwave dielectric properties, growth of grains, and composition of crystalline phase were analyzed in this article. In particular, the microwave dielectric properties of BaNi 2 V 2 O 8 ceramic should be first reported by us. The microstructures and crystalline phase of BaNi 2 V 2 O 8 ceramic were analyzed using a scanning electron microscope and X-ray diffractometer. BaNi 2 V 2 O 8 with rhombohedral structure and space group of R-3 was observed as the only crystalline phase. The ceramic that achieved the best sintering densification was considered to be a sample sintered at 950 °C for 4 h as seen from the results of microstructure and relative density. The relative density was considered to be the key factor to determine the ε r and Q × f value. Variation of the sintering process had little effect on the τ f values. The BaNi 2 V 2 O 8 sample fired at 950 °C for 4 h showed a low ε r value of 11.71, an excellent Q × f value of 48,350 GHz, and a relatively negative τ f value of − 49.2 ppm/°C.
Ba 1-x Sr x Ni 2 V 2 O 8 (x = 0, 0.05, 0.1, 0.15) ceramics were fabricated utilizing the solid-state reaction methods. The XRD and structural refinement results demonstrated an increased presence of a new Ba 0.5 Sr 0.5 Ni 2 V 2 O 8 phase with higher Sr 2+ content. With a distinctive tetragonal structure, this new phase markedly differed from the hexagonal structure of BaNi 2 V 2 O 8 . Our analyses of molecular polarization, packing fraction, and distortion of the [NiO 6 ] octahedra revealed that the ε r and τ f of Ba 0.5 Sr 0.5 Ni 2 V 2 O 8 surpassed those of BaNi 2 V 2 O 8 , while its Q × f value was lower. This explains the amplified ε r and τ f value, alongside the diminished Q × f value of the ceramics. The introduction of Sr 2+ elevated the τ f value of the ceramics from − 49.5 ppm/°C to − 7.8 ppm/°C. The Ba 0.85 Sr 0.15 Ni 2 V 2 O 8 specimen, sintered at 950 °C for 4 h, exhibited the most superior microwave dielectric performance: ε r = 12.7, Q × f = 34,200 GHz, τ f = − 7.8 ppm/°C. These outcomes underscore the promising practical potential of this ceramic.
危险品化学品经营许可证（带存储）