Electrical conductivity and impedance characteristics of RbH2PO4 crystal above room temperature

Abstract

The electrical conductivity measurements on single crystals of RbH2PO4 have been carried out in the temperature range from room temperature to 200 °C. The value of kBTε″ showed a high-temperature anomaly around Tp=113 °C for RbH2PO4. The total activation energies are obtained as Et=0.27 eV above Tp and Et=0.30 eV below Tp in RbH2PO4 for the ionic conduction of mobile ions, including bulk and surface conduction. From complex ac impedance spectra, we observed the impedance consisting of two regions for measuring frequency: the low-frequency region may be due to charge transport at the surface while the conduction mechanism of the high-frequency region seems to be the non-interacting Debye type. Relaxation times satisfy the Arrhenius relation. The activation energy concerned with ionic conduction EB=0.40 eV (T>Tp) and EB=0.52 eV(T<Tp). We separated bulk conductivity by means of complex impedance formalism. The bulk activation energies are obtained as EB,dc=0.41 eV above Tp and EB,dc=0.54 eV below Tp in RbH2PO4.