Achieving excellent temperature-stable dielectric properties of Bi0.5Na0.5TiO3-based lead-free ceramics via doping AgNbO3.

The lead-free ceramics (1 − x)(0.94 Bi 0. 4 7 Na 0. 4 7 Ba 0. 0 6 TiO₃-0.06BiAlO₃)- x AgNbO₃ (denoted as BNBTA- x AN) were synthesized via a solid-state sintering method. The effect of AgNbO₃ doping amount on dielectric properties of the ceramics was studied systematically. X-ray diffraction (XRD), scanning electron microscope (SEM) and Raman spectroscope were used to detect the structure of the ceramics. Temperature-dependent dielectric spectra, frequency-dependent dielectric constant and alternating current (ac) electric conductance at various temperatures were measured. The doping of AgNbO₃ greatly reduces dielectric constant around Curie temperature and thus enhances the temperature stability of the dielectric constant. The ceramic BNBTA-0.03AN exhibits excellent temperature-stable dielectric properties with temperature coefficient of capacitance (TCC) ≤ ± 15% between 55^∘C and 418^∘C with temperature window 363^∘C and small changes of dielectric constant and dielectric loss from 100 Hz to 1 MHz at different temperatures. The obtained ceramics are expected to be used in high-temperature capacitors due to its excellent temperature stability. [ABSTRACT FROM AUTHOR]