Article: Structural, specific heat and magnetoresistive properties of Gd0.7Ca0.3MnO3 Journal: International Journal of Materials Engineering Innovation (IJMATEI) 2014 Vol.5 No.3 pp.216 - 226 Abstract: Here, we report the structural, specific heat and magnetoresistive properties of orthorhombic perovskite structured Gd0.7Ca0.3MnO3, 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 Gd0.7Ca0.3MnO3 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. Inderscience Publishers - linking academia, business and industry through research

Title: Structural, specific heat and magnetoresistive properties of Gd_0.7Ca_0.3MnO₃

Authors: P. Negi; H.M. Agrawal; R.C. Srivastava

Addresses: Department of Physics, G.B. Pant University of Ag. and Technology, Pantnagar, Uttarakhand-263145, India ' Department of Physics, G.B. Pant University of Ag. and Technology, Pantnagar, Uttarakhand-263145, India ' Department of Physics, G.B. Pant University of Ag. and Technology, Pantnagar, Uttarakhand-263145, India

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.

Keywords: specific heat; magnetoresistive properties; XRD; Rietveld refinement; SEM; EDS; Fourier transform infrared; FTIR; Raman spectroscopy; structural properties; orthorhombic perovskite; sol-gel; rare earth manganites; perovskite manganites; polaron hopping; calcium; MnO3; gadolinium.

DOI: 10.1504/IJMATEI.2014.064279

International Journal of Materials Engineering Innovation, 2014 Vol.5 No.3, pp.216 - 226

Received: 02 Feb 2013
Accepted: 11 Sep 2013
Published online: 30 Aug 2014 *

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Title: Structural, specific heat and magnetoresistive properties of Gd0.7Ca0.3MnO3

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Title: Structural, specific heat and magnetoresistive properties of Gd_0.7Ca_0.3MnO₃