Synthesis and Characterization of Li-Modified AgTaO.

(LiAg)TaO (0 ≤ x ≤ 0.15) ceramics were fabricated by a mixed-oxide solid-state sintering route. Compositions with x ≤ 0.1 sintered into single-phase compounds and could be indexed according to the rhombohedral, $$ R{\bar{3}}c $$ or R3 c structure. For x > 0.1, x-ray diffraction revealed second-phase formation, probably LiTaO and AgTaO. It was noticed that the metastable and stable phase solubility limits for Li in AgTaO were x < 0.05 and 0.10 < x < 0.15, respectively. Raman and dielectric measurements confirmed the existence of a ferroelectric state in the compositions with x ≥ 0.05. This triggering of ferroelectricity supports the premise that substitution of relatively smaller ions increases the displacement of the A-site cation. The transition temperature was found to increase as a function of increasing Li concentration. Low-temperature (<100 K) Raman spectra and electron diffraction indicated that Li-doped AgTaO ceramics seem to adopt new tilt systems. [ABSTRACT FROM AUTHOR]