Correlation between infrared phonon modes and dielectric relaxation in Bi2O3-ZnO-Nb2O5 cubic pyrochlore

Analysis of the dielectric relaxation phenomena in Bi2O3-ZnO-Nb2O5 cubic pyrochlore utilizing the Arrhenius equation is revisited to include recent high-frequency measurements. The fitting parameters obtained are further analyzed by comparison with theoretical and experimental activation energies of better understood relaxation systems such as dipolar glasses and relaxor ferroelectrics. The attempt jump frequency obtained from the Arrhenius fit (nu(0)similar to4.385 THz) is found in correspondence with the resonant frequencies of the polar phonon modes previously identified by infrared spectroscopy. This correlation, and in particular the role of the O-A-O and O'-A-O' bending phonon modes in driving the relaxation, is discussed. (C) 2002 American Institute of Physics.