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Title: Room temperature magnetocaloric effect and refrigerant capacitance in La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanotube arrays

High aspect ratio La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanotube (NT) arrays have been synthesized using nitrates based sol-gel precursor by nanoporous anodized aluminum oxide template assisted method. Their phase purity and microstructures were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. Magnetocaloric effect (MCE) of as prepared NTs was investigated by means of field dependence magnetization measurements. Significant magnetic entropy change, −△S{sub M} = 1.6 J/kg K, and the refrigerant capacitance, RC = 69 J/kg, were achieved near the transition temperature at 315 K for 5 T. For comparison, a bulk sample was also prepared using the same precursor solution which gives a value of −△S{sub M} = 4.2 J/kg K and a RC = 165 J/kg. Though the bulk sample exhibits higher △S{sub M} value, the NTs present an expanded temperature dependence of −△S{sub M} curves that spread over a broad temperature range and assured to be appropriate for active magnetic refrigeration. The diminutive MCE observed in manganite NTs is explained by the increased influence of surface sites of nanograins which affect the structural phase transition occurred by external magnetic field due to the coupling between magnetism and the lattice in manganese perovskites. Our report paves the way for further investigation in 1D manganite nanostructured materials towards applications in such magneticmore » refrigeration technology or even on hyperthermia/drug delivery.« less
Authors:
; ; ; ;  [1] ;  [1] ;  [2]
  1. IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Sciences, University of Porto, Porto (Portugal)
  2. (Portugal)
Publication Date:
OSTI Identifier:
22310971
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 105; Journal Issue: 8; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ALUMINIUM OXIDES; ASPECT RATIO; LANTHANUM COMPOUNDS; MAGNETIC FIELDS; MAGNETIC PROPERTIES; MAGNETIZATION; MANGANATES; MICROSTRUCTURE; NANOTUBES; PEROVSKITES; PHASE TRANSFORMATIONS; REFRIGERANTS; SCANNING ELECTRON MICROSCOPY; STRONTIUM COMPOUNDS; SURFACES; TEMPERATURE DEPENDENCE; TEMPERATURE RANGE 0273-0400 K; TRANSITION TEMPERATURE; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY