Structural, specific heat and magnetoresistive properties of Gd_0.7Ca_0.3MnO₃
by P. Negi; H.M. Agrawal; R.C. Srivastava
International Journal of Materials Engineering Innovation (IJMATEI), Vol. 5, No. 3, 2014

Abstract: Here, we report the structural, specific heat and magnetoresistive properties of orthorhombic perovskite structured Gd_0.7Ca_0.3MnO₃, synthesised by modified sol-gel technique. X-ray diffraction along with the Rietveld refinement confirms the pure phase of the sample and the crystallite size comes out to be ∼42 nm. Scanning electron micrograph shows the grain distribution having average particle size ~71 nm. Energy dispersive spectroscopy confirms the stoichiometry of the composition. The sample is also characterised by Raman spectroscopy for structural and phase confirmation. The functional group of Gd_0.7Ca_0.3MnO₃ was also analysed from its Fourier transform infrared (FTIR) spectrum. The specific heat of the sample is measured in the temperature range of 2 to 300 K. Resistivity measurements with and without magnetic field was performed. The activation energy in absence of magnetic field is 0.162 eV which reduces to 0.154 eV in presence of 8 T magnetic field. The observed electrical behaviour is explained in terms of polaron hopping mechanism.

Online publication date: Sat, 30-Aug-2014

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