The aging effect within incommensurate phase in TlGaSe2

The effects of physical aging on the dielectric constant of TlGaSe₂ layered ferroelectric crystal were investigated. Isothermal aging processes were done within incommensurate phase in TlGaSe₂ ferroelectric single crystals when slow cooling was interrupted for a time at a constant temperature. The dielectric constant exhibited an unusual behaviour: it decreased exponentially with time. The results can be interpreted taking into account the interaction of the structure of the incommensurate phase with crystal fields of defects randomly distributed in the crystal structure. The measurements show that there are two relaxation mechanisms associated with two relaxation sites in mentioned temperature interval. This means that two different types of incommensurate phases occur in mentioned temperature interval.