Dielectric and Raman studies of(BaxPb1−x)(Yb0.5Nb0.5)O3

Abstract

Dielectric dispersion and Raman studies are carried out on the solid solution series(BaxPb1−x)(Yb0.5Nb0.5)O3 from x = 0.0 to 0.3. The x-ray diffraction analysis indicates that with the substitution ofBa2+, the intensity of the peaks corresponding to antiparallel displacement ofPb2+ decreases and the structure becomes cubic. The low frequency dielectric dispersion studies indicatethat the series undergoes a transition from an antiferroelectric to a relaxor ferroelectric with variationof x. Raman spectra of the compositions indicate the presence of a greater number of modes forthe compounds with cubic structure (). A new mode at 420 cm−1 is observedfor the compounds with Ba2+ substitution. The intensity of this mode increases monotonically with increase inBa2+ substitution and this has been attributed to the commencement of local distortion. Thiscould be responsible for the appearance and increase in the diffuseness aroundTmax, the temperature corresponding to .