Dielectric and impedance spectroscopy of (Ba, Sm)(Ti, Fe)O3 system in the low-medium frequency range

Abstract

The (Ba, Sm)(Ti, Fe)O 3 system, combination of non-ferroelectric samarium ortho-ferrite and ferroelectric barium titanate, was prepared by using a standard hightemperature solid-state reaction technique. Structural analysis of the material using room temperature XRD data confirmed the formation of the single-phase compound. Detailed structural analysis of the system using Rietveld refinement method exhibits the tetragonal structure with polar space group P4mm. Room temperature micrograph of the sample recorded by a scanning electron microscope shows uniform distribution of grains of various dimension and with less voids confirming the formation of high density sample. Studies of dielectric and impedance spectroscopy characteristics of the sample were carried out in the low-frequency (100-1300 mHz) and the high-frequency region (100 Hz-1 MHz) at different temperatures (25-300°C). The frequency dependence of dielectric constant of both low and high frequency plots was explained on the basis of Maxwell-Wagner mechanism, Shockley Read statistics and Koops phenomenological theories. Ferroelectric phase transition appears in both the low-and high-frequency regions. Nyquist plots show the contributions of grain, grain boundary and electrode effect. The frequency dependence of conduction mechanisms were explained on the basis of correlated barrier hopping model and overlapping large polaron tunneling models.The P-E hysteresis loop confirms the ferroelectricity in the material.

Nanostructured Lead Sulphide Depositions by AACVD Technique Using Bis(Isobutyldithiophosphinato)Lead(II) Complex as Single Source Precursor and Its Impedance Study

“…This became frequency independent above 10 5 Hz due to a bulk effect. Higher values of dielectric constant at lower frequencies can be explained on the basis of Koops phenomenological model and Maxwell-Wagner type polarization as dielectric materials are supposed to consist of poor grain boundaries that contribute more at low frequencies and are separated by good conducting grains [32]. Dispersion observed at lower frequencies, i.e., below 10 2 Hz was attributed to interfacial polarization while that above 10 4 Hz was due to dipolar polarization.…”

Effect of cerium oxide addition on optical, electrical and dielectric characteristics of (Bi0.5Na0.5)TiO3 ceramics

“…The fitting of the plots have been done by using Zsimpwin Software. The corresponding semicircular curves are drawn by considering three pairs of ¢ Z and  Z from experiment data and fitted with a circle equation [30]. The fitting process was repeated many times till the experiment data fit well with the depressed semicircle.…”