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Influence of grain size on magnetocaloric effect in the nanocrystalline La0.8Te0.2Mno3
Published in
2011
Volume: 10
   
Issue: 4-5
Pages: 597 - 600
Abstract
The nanocrystalline La0.8Te0.2MnO3 samples are prepared by sol-gel method and show rhombohedral crystal structure with R3c space group at room temperature. The calculated crystallite sizes are ∼55 nm, 40 nm and 25 nm for calcined at 700°C, 800°C and 900°C temperatures. The SEM images show the grain size increases as the calcination temperature increases and the values are in good agreement with that obtained from X-ray diffraction analysis. The samples undergo paramagnetic to ferromagnetic transition and follow CurieWeiss law in the paramagnetic region. The maximum entropy change are ∼3.2 J kg-1 K-1, 3 J kg-1 K-1 and 2 J kg-1 K-1 for a field change of 20 kOe for 55 nm, 40 nm and 25 nm samples respectively. In the framework of Landau theory of phase transition, the experimentally observed magnetic entropy change and theoretical predicted model fits well for all the nanoparticles. © 2011 World Scientific Publishing Company.
About the journal
JournalInternational Journal of Nanoscience
ISSN0219581X
Open AccessNo
Concepts (30)
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    Calcination temperature
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    Curie weiss law
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    Ferromagnetic transitions
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    Field change
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    Grain size
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    LANDAU THEORY
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    Magnetic
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    Magnetic entropy change
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    Magnetocaloric
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    Maximum entropy
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    MODEL FIT
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    Nanocrystallines
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    PARAMAGNETIC REGION
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    RHOMBOHEDRAL CRYSTALS
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    Room temperature
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    Sem image
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    Space groups
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    Calcination
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    Crystal structure
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    Entropy
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    Grain size and shape
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    Lanthanum
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    Manganese oxide
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    Nanomagnetics
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    Nanoparticles
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    Paramagnetic materials
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    Paramagnetism
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    Sol-gel process
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    X ray diffraction analysis
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    Magnetocaloric effects