Red Shift in Optical Absorption Tall and Superparamagnetism of gamma-Fe2O3 Nanoparticles in a Polymer Matrix

reportActive / Technical Report | Accession Number: ADP014282 | Open PDF

Abstract:

Well defined spherical particles of gamma - Fe2O3 have been synthesized in the pores of a polymer matrix in the form of beads by an ion exchange and precipitation reaction. The particle size distribution is a gaussian with an average diameter of 80 A. The DC magnetic susceptibility and the magnetization of the nanocomposite has been measured between 4 and 300 K using a Faraday balance and a magnetometer, respectively. The magnetic measurements demonstrate that the particles are superparamagnetic with a blocking temperature T about 55 K. The optical absorption edge of the mesoscopic system is red shifted with respect to single crystal films of gamma - Fe2O3 with an absorption tail extended deeply in the gap. Although lattice distortion and existence of excitonic states in the gap can explain the absorption behavior, the red shift can successfully be explained by the quantum confinement of an electron-hole pair in a spherical well.

Author(s):
Vassiliou, John K. ; Otto, Jens W. ; Mehrotra, V. ; Davis, J. J.
Author Organization(s):
VILLANOVA UNIV PA DEPT OF PHYSICS
Descriptive Note:
Conference proceedings
Supplementary Note:
This article is from the Mat. Res. Soc. Symposium Proceedings, v740 p301-307, 2003. This article is from ADA417952 Materials Research Society Symposium Proceedings Volume 740 Held in Boston, Massachusetts on December 2-6, 2002. Nanomaterials for Structural Applications
Pagination:
0007

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DOCUMENT & CONTEXTUAL SUMMARY

Distribution:
Approved For Public Release

RECORD

Collection: TR
Identifying Numbers
Monitor Series:
XD
 Subject Terms
Joint Capability Areas:
JCA_6_Net Centric; JCA_6.1_Information Transport
Modernization Areas:
Microelectronics
Communities of Interest:
Energy and Power Technologies
Descriptor(s):
*OPTICAL PROPERTIES, *GAMMA RAYS, *ABSORPTION, *IRON OXIDES, PARTICLE SIZE, MAGNETIC FIELDS, SYMPOSIA, POLYMERS, COMPOSITE MATERIALS, QUANTUM THEORY, THIN FILMS, SINGLE CRYSTALS, HOLES(ELECTRON DEFICIENCIES), MATRIX MATERIALS, ELECTRONS, PRECIPITATION, RADIATION ABSORPTION, LATTICE DYNAMICS, FARADAY EFFECT, DIRECT CURRENT, ION EXCHANGE, PARAMAGNETISM, MAGNETOMETERS
Field(s)/Group(s):
Laminates and Composite Materials, Electricity and Magnetism
Keyword(s):
COMPONENT REPORT, *RED SHIFT, *NANOPARTICLES, * POLYMER MATRIX, *SUPERPARAMAGNETISM, ABSORPTION TAIL, NANOCOMPOSITES
Report Date:
2003 Jan 01
Creation Date:
2003 Dec 03