Tetragonal tungsten bronze compounds: relaxor vs mixed ferroelectric - dipole glass behavior

Abstract

We demonstrate that recent experimental data (E. Castel et al J.Phys. Cond. Mat. {\bf 21} (2009), 452201) on tungsten bronze compound (TBC) Ba${}_2$Pr${}_x$Nd${}_{1-x}$FeNb${}_4$O${}_{15}$ can be well explained in our model predicting a crossover from ferroelectric ($x=0$) to orientational (dipole) glass ($x=1$), rather then relaxor, behavior. We show, that since a "classical" perovskite relaxor like Pb(Mn${}_{1/3}$ Nb${}_{2/3}$)O${}_3$ is never a ferroelectric, the presence of ferroelectric hysteresis loops in TBC shows that this substance actually transits from ferroelectric to orientational glass phase with $x$ growth. To describe the above crossover theoretically, we use the simple replica-symmetric solution for disordered Ising model.

5 two-column pages, 4 figures

References in corpus (2)

• A reassessment of the Burns temperature and its relationship to the diffuse scattering, lattice dynamics, and thermal expansion in the relaxor PMN
• Griffiths phase manifestation in disordered dielectrics