AgNbO 3 antiferroelectric (AFE) ceramics have attracted much attention because of their high-energy storage performance and environment-friendly characteristics. In this paper, Sb 2 O 5 -doped AgNbO 3 ceramics are prepared by the traditional solid-state reaction method, and the effects of phase structure, microstructure, dielectric, and ferroelectric properties are systematically investigated. Lattice shrinkage and obvious grain size change are caused by the introduction of Sb 5+ ions. The dielectric constant increases significantly with the introduction of Sb 5+ ( ε r from 210 to 550 at room temperature), and the phase transition temperatures of M 1 –M 2 and M 2 –M 3 shift to a lower temperature as the Sb-doping level increases. High relaxor degree γ = 1.97 of M 1 –M 2 peak is achieved in the AgNb 0.98 Sb 0.02 O 3 ceramics, showing typical relaxor antiferroelectric characteristics. Simultaneously, the relaxor characteristics lead to lower remanent polarization values, a finer P–E hysteresis loop, and an improved AFE phase in AgNb 0.98 Sb 0.02 O 3 ceramics. Compared to pure AgNbO 3 , AgNb 0.98 Sb 0.02 O 3 ceramics have a higher recoverable energy density ( J rec = 1.70 J/cm 3 ) and higher energy efficiency ( η = 30.05%).
AgNbO3-based Pb-free antiferroelectric (AFE) ceramics have attracted increasing interest owing to their excellent potential in energy storage applications. Herein, a high recoverable energy storage density (Wrec) of 7.62 J/cm3 is realized in La-doped AgNbO3 ceramics prepared via tape casting. The high Wrec is attributed to high breakdown strength Eb of 380 kV/cm induced by dense microstructure as well as fine grain size and enhanced AFE stability stemming from M2 phase and reduced tolerance factor t. The high Wrec exceeding 6 J/cm3 was maintained in a wide temperature range of 20–150 °C and exhibited frequency stability with less than 8% variation in a range of 1–200 Hz. The discharge energy density Wd exhibited temperature stability at 30–110 °C with less than 9% variation. Our research provides a good method for producing AgNbO3-based ceramics having high energy storage performances.
In RF devices, the microwave ceramics possessing an ultrahigh dielectric constant are instrumental in facilitating the miniaturization of electronic components. However, ceramic systems with ultrahigh dielectric constant are rare and typically exhibit poor temperature stability and high dielectric loss. Research on developing new systems with ultrahigh ε r , low dielectric loss, and low τ f is crucial. The microwave ceramics of (1- x ) CaTiO 3 - x AgNbO 3 [(1- x ) CT- x AN, x = 0.4–0.8] were synthesized via solid-state reaction. The XRD and Rietveld analysis data have confirmed that the CT-AN ceramic system is in an orthorhombic structure with a space group of Pbcm . Elevated AgNbO 3 content leads to increased grain size in ceramics. These ceramics possess a high relative density (>98 %) and show excellent microwave dielectric properties. With increasing AgNbO 3 content, the ε r ascends from 106 to 886, while Q×f descends from 1500 GHz to 381 GHz. And τ f fluctuates within a range of 400–1000 ppm/°C, with a minimum of 403 ppm/°C when x = 0.5. Dielectric anomalies due to phase transitions were observed within low-frequency spanning 500 Hz to 200 k Hz, and the dielectric loss is zero at 200 k Hz at 25–100 °C. CT-AN ceramics demonstrate an ultrahigh dielectric constant, and further research into modulating its temperature coefficient of the resonant frequency could unlock their potential for applications in miniaturized antennas and capacitors.
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