Min Yang,Yong Zheng,Weimin Ding,Xuepeng Lu,Lan Wang,Zhiyi Jiang,Bo Li,Zuowei Dong
This study addresses the challenge posed by the high sintering temperature (>850 °C) required for current high-performance BaZnP 2 O 7 -based ceramics by investigating the substitution of V 5+ at the P-site in BaZnP 2 O 7 ceramic. The objective was to lower the sintering temperature to below 850 °C while preserving the high-quality characteristics of the ceramics. Results reveal that the solubility of V 5+ in BaZnP 2 O 7 ceramics is limited, and secondary phases such as BaZn 2 (PO 4 ) 2 and Ba 3 V 2 O 3 (PO 4 ) 3 were formed when the concentration of V 5+ exceeds 0.005. The substitution of V 5+ for P 5+ effectively reduces the sintering temperature of BaZnP 2 O 7 ceramics from 840 (at x = 0) to 680 °C (at x = 0.10). The dielectric constant ( ε r ) of BaZn(P 1- x V x ) 2 O 7 ceramics is primarily influenced by porosity and the presence of secondary phases. The losses due to anharmonic vibrations in BaZn(P 1- x V x ) 2 O 7 ceramics were effectively reduced, leading to an increase in Q × f to ∼70,000 GHz at x = 0.005. The temperature coefficient of resonant frequency ( τ f ) is mainly affected by bond energy ( E ) and the content of the Ba 3 V 2 O 3 (PO 4 ) 3 phase. Ultimately, the BaZn(P 0.995 V 0.005 ) 2 O 7 ceramic sintered at 820 °C for 4 h exhibited the optimal microwave dielectric properties: ε r = 8.24, Q × f = 75,419 GHz, and τ f = −34.76 ppm/°C.
Fangyi Huang,Xiaoli Tang,Qin Zhang,Xingyu Huo,Yuanxun Li,Xian Jian,Hua Su
In this study, the microwave dielectric properties of Co 2+ -substituted BaZnP 2 O 7 ceramics prepared through conventional solid-state synthesis were investigated. X-ray diffraction, Rietveld refinement, energy-dispersive spectroscopy, and Raman spectroscopy all indicated that BaZn 1− x Co x P 2 O 7 ceramics sintered at 875°C were composed of a single phase. The lattice strain and crystallite size were estimated using Williamson–Hall (W–H) method. Both the scanning electron microscopy images and density measurements showed that Co 2+ ions had an effect on the grain growth and densification of ceramics. The microwave dielectric properties were influenced by the intrinsic and extrinsic factors that varied with the increase of x value. An optimal performance ( ε r = 7.62, Q × f = 600 45 GHz, and τ f = −74 ppm/°C) was achieved at x = .01. The porosity and relative density played a significant role in the dielectric constant ε r : the denser the ceramic structure, the larger the dielectric constant. The Q × f and τ f values were negatively correlated with the full width at half maximum of the Raman vibrational peak at approximately 1049 cm −1 . Moreover, the Q × f value was improved compared to that of the undoped BaZnP 2 O 7 ceramics. Therefore, cobalt ion substitution is an effective strategy to enhance the performance of microwave dielectric ceramics.
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