Phase transitions and dielectric properties of the Ag1-xBix/3NbO3 system

Ceramics of Ag1-xBix/3NbO3 (x < 0.6) perovskite solid solutions were obtained by solid-state reaction. The tilting systems (a(-)a(-)c(+) for x=0.1-0.3 and a(0)a(0)c(+) for x=0.4-0.5) were determined from the splitting of the peaks and the superlattice lines in the x-ray diffraction patterns. The dielectric properties of the Ag1-xBix/3NbO3 (x=0.1-0.6) ceramics were measured in the range of 100-870 K at 1 kHz-1 MHz. Based on the dielectric measurements, three phase transitions occurred for x=0.1-0.3, and their temperatures decreased with the increasing Bi content. A new diffuse phase transition occurred for x > 0.3. A T-x phase diagram was constructed from the dielectric data. Excellent temperature-stable dielectrics were obtained at x=0.25 in the vicinity of the diffuse phase transition.