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

Journal Article · Mon Aug 25 04:00:00 EDT 2014 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4894175· OSTI ID:22310971

Sousa, C. T.; Pires, A.; Pereira, A. M.; Araujo, J. P. ^[1]; Lopes, A. M. L. ^[1]

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1. IFIMUP and IN-Institute of Nanoscience and Nanotechnology, Department of Physics and Astronomy, Faculty of Sciences, University of Porto, Porto (Portugal)

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 magnetic refrigeration technology or even on hyperthermia/drug delivery.

• OSTI ID: 22310971
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 8 Vol. 105; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

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