Dielectric properties of Li +-exchanged mixed FeCr oxide pillared phosphate

Abstract

The dielectric properties of mixed FeCr oxide-pillared α-zirconium phosphate and derivatized Li +-exchanged have been studied by impedance spectroscopy. The pure FeCr pillared material exhibits low electronic conductivity and presents only a dielectric relaxation. However, the Li +-exchanged sample is an ionic conductor and subtracting the dc contribution, a dielectric relaxation at low frequency is observed. The Li + ions distribution presents a two-potential-well system; the ions localized at small pores cannot be displaced over long distances and their short hopping transitions determine the dielectric properties. On other hand, only a fraction of the ions located in large pores are free and can be displaced over long distances and the remainders are fixed and can only make short displacements. These ions behave like jumping dipoles and produce a dielectric relaxation at low frequencies and high temperatures.