Abstract:
The dielectric and optical properties, as well as the time dependences of the permittivity in an electric field applied along the [001] direction, are studied in Na$_{1/2}$Bi$_{1/2}$TiO$_3$–5%BaTiO$_3$ single crystals lying near the morphotropic phase boundary. It is shown that, even in the absence of an electric field, dielectric and optical hysteresis associated with the coexistence of tetragonal and rhombohedral phases is observed in a wide temperature range, and the relative volume fractions of the two phases largely depend on temperature. It was found that at temperatures below the temperature of the morphotropic phase transition, the induction of the ferroelectric phase occurs without a delay time, which distinguishes the samples under study from PbMg$_{1/3}$Nb$_{2/3}$O$_3$–$x$%PbTiO$_3$ solid solutions. The results obtained are explained by different sizes of polar nanoregions in the low-temperature phase.
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