Effect of V5+ substitution on the sintering behavior, phases assemblage, Raman characteristics, and microwave dielectric properties in BaZnP2O7 ceramics

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.