Abstract
Ag(NbxTa1-x)O-3 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 degrees 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 R (3) over barc/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 less than or similar to-180 degrees C. Dielectric measurements for x = 0.75 demonstrated a new anomaly in epsilon(r) at similar to 42 degrees C, thereby suggesting the possibility of an additional phase. (C) 2015 Elsevier Ltd. All rights reserved.