Structural, optical and dielectric investigations on RECr0.85Mn0.15O3 (RE = Ho, Gd and Pr) nanoparticles

Abstract

We hereby report the room-temperature structural and optical characterization of RECr0.85Mn0.15O3 (RECMO, RE = Ho, Gd and Pr) compounds synthesized by the auto-combustion sol–gel route. Their low temperature dielectric properties are also presented. The RECMO compounds crystallize in an orthorhombic Pbnm symmetry with an average grain size range of 51–80 nm. Structural analysis reveals an increase in the structural distortion compared to that of the undoped bulk compounds. Optical measurements exhibit a significant reduction in bandgap values for RECMO nanoparticles when compared with their undoped bulk compounds. Further, from the absorbance measurements various optical parameters such as skin depth, extinction coefficient, refractive index and optical conductivity were also calculated. The dielectric analysis confirms the lower values of the dielectric permittivity and dielectric loss than those of their corresponding bulk compounds. AC conductivity versus frequency and temperature data are fitted according to the Jonscher’s power law and Arrhenius law, respectively. The small polaron hopping is responsible for the electric conduction in these compounds. The tunability of the optical and dielectric properties as a result of substitution and particle size reduction makes these materials useful for various potential applications in photocatalysis, optoelectronics and low permittivity dielectrics.