Microstructure and charge carrier dynamics in Dy substituted phase stabilized cubic Bi2O3

Abstract

Room temperature phase stabilization of cubic Bi₂O₃ has been achieved by adding Dy₂O₃ as the dopant, using a low temperature citrate-auto-ignition method. The samples were sintered at different temperatures retaining the cubic fluorite structure. Rietveld refinement of the X-ray diffraction profiles has given detailed microstructural information of the prepared samples. The transmission electron micrographs confirmed the presence of atomic planes as obtained from X-ray diffraction. The UV-Vis spectra show a red shift of the absorption peak with the increase in sintering temperature. Impedance spectroscopy studies of the samples exhibited thermally activated non-Debye type relaxation process. In addition, studies of the electrical conductivity have suggested the negative temperature coefficient of resistance (NTCR) behavior of the samples. The comparable values of activation energies, obtained from different parameters, indicated that the ions follow the same type of mechanism for conduction as well as for relaxation. The temperature independence of the mechanisms has been confirmed from scaling of different spectra. The correlation between structural and electrical properties of the samples has been discussed and interpreted accordingly.