INVESTIGADORES
HODAK Jose Hector
artículos
Título:
Magnetic properties of Co-ferrite-doped hydroxyapatite nanoparticles having a core/shell structure
Autor/es:
PETCHSANG, N.; PON-ON, W.; HODAK, J.H.; TANG, I.M.
Revista:
JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS
Referencias:
Año: 2009 vol. 321 p. 1990 - 1995
ISSN:
0304-8853
Resumen:
The magnetic properties of Co-ferrite-doped hydroxyapatite (HAP) nanoparticles of composition Ca10-3xFe2xCox(PO4)6(OH)2
(where x=0, 0.1, 0.2, 0.3, 0.4 and 0.5% mole) are studied. Transmission
electron microscope micrograms show that the 90 nm size nanoparticles
annealed at 1250 °C have a core/shell structure. Their electron
diffraction patterns show that the shell is composed of the
hydroxyapatite and the core is composed of the Co-ferrite, CoFe2O4. Electron spin resonance measurements indicate that the Co2+
ions are being substituted into the Ca(1) sites in HAP lattice. X-ray
diffraction studies show the formation of impurity phases as higher
amounts of the Fe3+/Co2+ ions which are substituted into the HAP host matrix. The presence of two sextets (one for the A-site Fe3+ and the other for the B-site Fe3+) in the Mössbauer spectrum for all the doped samples clearly indicates that the CoFe2O4.cores
are in the ferromagnetic state. Evidence of the impurity phases is seen
in the appearance of doublet patterns in the Mössbauer spectrums for
the heavier-doped (x=0.4 and 0.5) specimens. The decrease in the
saturation magnetizations and other magnetic properties of the
nanoparticles at the higher doping levels is consistent with some of
the Fe3+ and Co2+ which being used to form the CoO and Fe2O3 impurity phase seen in the XRD patterns. © 2009 Elsevier B.V. All rights reserved.