Abstract
In this study, nanosized La1-xCaxFeO3 (0.00≤x≤0.40) compounds prepared via sol-gel method followed by heat treatment at 1100oC for 24 hours are studied. Crystal structure, microstructure, surface morphology and temperature-dependent resistivity of the samples are investigated. TEM investigation reveals nanoparticles with an average size of 35nm produced from the sol-gel process. The crystal structure of the compounds belongs to an orthorhombically distorted perovskite structure with Pbnm space group. Lattice distortion and cation size mismatch increase with an increase in Ca and particle and grain growth are suppressed by Ca doping. Electrical conduction is explained via thermally activated hopping of small polarons. Unit cell volume, charge ordering temperature, and activation energy for small polarons decrease linearly with an increase in cation size mismatch. Room temperature resistivity decreases with Ca doping and gets its minimum value for 30% Ca at which the orthorhombic distortion is maximum.
Highlights
Rare-earth (Re) transition metal perovskite oxides attract attention due to their electronic and magnetic properties, such as insulator to metal and paramagnetic to ferromagnetic phase transitions, magnetoresistance, electroresistance, magnetocaloric effect and charge order properties
The given structural model was refined with the peak shapes of the experimental patterns were assumed to be a Thompson-Cox-Hastings (TCH) pseudo-Voigt profile functions
goodness of fit (GoF) was calculated by the ratio Re/Rwp, where Re and Rwp are the expected weighted and weighted profile factors
Summary
Rare-earth (Re) transition metal perovskite oxides attract attention due to their electronic and magnetic properties, such as insulator to metal and paramagnetic to ferromagnetic phase transitions, magnetoresistance, electroresistance, magnetocaloric effect and charge order properties. LaFeO3 is a semiconductor/insulator perovskite oxide and its derived compounds by replacement of some of La atoms by other Re or alkaline earth (Ae) elements give rise to significant physical and chemical properties with promising applications in advanced technologies as in electronics, magnetics, fuel cells, gas sensors, and catalysts [1]. Ae doping has an influence on particle size (PS) and grain size (RG). PS has an effect on electronic, magnetic and chemical properties and is an important parameter in determining the performance of the material
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