Synthesis and characterization of solid solution Ag(NbxTa1−x)O3 (x = 0, 0.25, 0.5, 0.75, 1.0)

Ag(NbxTa1−x)O3 has been synthesized for x = 0, 0.25, 0.50, 0.75, and 1.0 by the mixed oxide route. The synthesis parameters were set to produce single-phase ceramics. Uniaxial pressure (60 MPa) was applied for 3 min, followed by cold isostatic pressing (200 MPa) for 2 min in order to obtain dense green pellets. Cooling rates ≤1.5 °C/min proved effective for optimum sintering for compositions with x ≥ 0.25. X-ray diffraction of compositions with x ≤ 1 could be indexed according to the Pbcm   and R3¯c/R3c symmetries, respectively. Electron diffraction, dielectric and Raman spectra indicated that the correlation length of cation displacements decreased as x decreased. The dielectric and Raman spectra also suggested the possibility of a new phase for AgTaO3 at ≲−180 °C. Dielectric measurements for x = 0.75 demonstrated a new anomaly in ɛr at ∼42 °C, thereby suggesting the possibility of an additional phase.