Dipole glass behavior in ferroelectric pyridinium periodate

Detailed investigations have been performed on the dielectric behavior in polycrystalline pyridinium periodate C5NH6IO4 at temperatures 100K≤T≤340K and frequencies 10Hz≤ν≤105Hz. A remarkable dielectric relaxation is clearly observed at temperatures below 250 K. The frequency dependence of the dielectric constant is analysed by use of a sum of two kinds of relaxation process with different strength. The relaxation time for the dominant relaxation process obeys the Arrhenius law with the activation energy E=3869±15K and the pre-exponential factor τ0=3.3×10−12s. The dominant one is regarded as clear evidence of the dipole glass state in C5NH6IO4. Its origin is thought to be the coupled reorientation of the pyridinium cation and the IO4 anion. The overall temperature dependence of the relaxation time for the other weak relaxation process shows a quite different pattern which can hardly be described by the Arrhenius law. The weak one is considered to originate from the ferroelectric domain wall motion.

► C5NH6IO4 comprises the pyridinium cation and the IO4 anion.
► The coupled motion of the two ions causes the dielectric relaxation.
► The dielectric relaxation shows typical aspects of the dipole glass.
► The dipole glass and ferroelectric states coexist in C5NH6IO4.