Abstract
We have prepared LaCrO3 (LCO) and 10% Ir doped LCO samples by the solid state reaction method and studied the electrical modulus and the other dielectric properties of the samples by means of the impedance spectroscopy in the −100 °C to 100 °C range, with steps of 20 °C. It has been clearly observed that the dielectric properties change due to Ir doping. The absolute dielectric constant value of Ir doped LCO has decreased and this reduction was attributed to decreasing Cr6+ ions which may play a vital role in space charge polarization and charge hopping. A plateau region appeared in the temperature-dependent real electrical modulus M′ versus f curves of the pure LCO sample while almost no plateau region is visible in the Ir doped LCO sample. The temperature-dependent imaginary modulus M′′ versus f curves has two peaks at each temperature; one of the peaks is at low frequency and the other at the high frequency region, which shifts through higher frequency region with increasing temperature. This originates from free charge accumulation at the interface with the increase of the temperature. Furthermore, it has been seen that the Ir doped LCO sample has higher impedance and resistance values than the undoped LCO sample at the same frequency and temperature. This phenomenon was attributed to doped Ir ions behaving like a donor in LCO because LCO is a p-type compound. Moreover, the activation energy values of 0.224 eV and 0.208 eV for LCO and of 0.161 eV and 0.265 eV for the Ir doped LCO have been obtained from the slopes of the ρdcvs. (kT)−1 curves, respectively. Also the activation energies were calculated from the slopes of the fmaxvs. (kT)−1 curves and the obtained results from low frequency region were in good agreement with ρdcvs. (kT)−1 ones.
Highlights
The perovskite oxide compounds have the general stoichiometry of ABO3 formula in which A and B are cations and the A cation is larger than the B cation
This originates from free charge accumulation at the interface with the increase of the temperature
A deviation from the semicircular shape of modulus arc of both samples has been observed with increasing temperature in high frequency region, and the semicircular arc for LCO sample has only formed at À100 and À80 C, though the semicircular arc for the Ir doped LCO sample has only formed at the other frequencies except 60, 80 and 100 C
Summary
The perovskite oxide compounds have the general stoichiometry of ABO3 formula in which A and B are cations and the A cation is larger than the B cation. The perovskite oxide materials have grabbed considerable attention among scientists due to their electrical, dielectric, magnetic, thermal, mechanical, sensing and optical properties.[1,2,3,4,5,6,7] the exibility in the chemical composition of these materials offers excellent possibilities in terms of control of their structures via substitution of a number of transition metals into the A or B cation sites.[8,9,10,11,12] Such properties make perovskite oxides very promising for several applications. The electrical, dielectric, magnetic and optical properties of LCO can be changed by doping both A (La) and B (Cr) cation sites with transition metals that offer excellent possibility to researchers to large application areas.[35,36,37,38] The doped transition metal type has signi cant impact on the LCO properties because it changes almost all LCO parameter including physical and chemical. Many doping studies have been conducted on the LCO with various transition metals including Sr,[39] Co, Ni,[41] V,41 Cu,[41] Mn, Ca,[43] Pd44 etc
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
