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Sol-gel synthesis and characterization of polycrystalline GdFeO3 and Gd3Fe5O12 thin films
Linköpings universitet, Institutionen för fysik, kemi och biologi, Oorganisk Kemi. Linköpings universitet, Tekniska fakulteten.
Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
Uppsala University.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.ORCID-id: 0000-0002-0314-4291
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2009 (Engelska)Ingår i: Journal of Sol-Gel Science and Technology, ISSN 0928-0707, E-ISSN 1573-4846, Vol. 49, nr 2, s. 253-259Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Thin films of the perovskite and garnet structured gadolinium ferrites GdFeO3 and Gd3Fe5O12 have been synthesized by a sol-gel method, based on stoichiometric mixtures of acetyl acetone chelated Gd3+ and Fe3+ dissolved in 2-methoxy ethanol. After spin coating onto Si wafers, and heating in air at 700 degrees C for 20 h, neatly grown essentially single phase films were obtained. From X-ray photoelectron spectroscopy an iron deficiency is observed in the uppermost layer of both films, implying that the crystallites preferably end in planes rich in Gd and O but not in Fe. The films were also characterized by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, and magnetic measurements.

Ort, förlag, år, upplaga, sidor
2009. Vol. 49, nr 2, s. 253-259
Nyckelord [en]
Thin film, Gadolinium iron oxides, Sol-gel synthesis, Magnetic properties, XPS
Nationell ämneskategori
Naturvetenskap
Identifikatorer
URN: urn:nbn:se:liu:diva-16962DOI: 10.1007/s10971-008-1859-0OAI: oai:DiVA.org:liu-16962DiVA, id: diva2:200849
Tillgänglig från: 2009-02-28 Skapad: 2009-02-27 Senast uppdaterad: 2021-10-13
Ingår i avhandling
1. Colloidal synthesis of metal oxide nanocrystals and thin films
Öppna denna publikation i ny flik eller fönster >>Colloidal synthesis of metal oxide nanocrystals and thin films
2008 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

A main driving force behind the recent years’ immense interest in nanoscience and nanotechnology is the possibility of achieving new material properties and functionalities within, e.g., material physics, biomedicine, sensor technology, chemical catalysis, energy storing systems, and so on. New (theoretical) possibilities represent, in turn, a challenging task for chemists and physicists. An important feature of the present nanoscience surge is its strongly interdisciplinary character, which is reflected in the present work.

In this thesis, nanocrystals and thin films of magnetic and ferroelectric metal oxides, e.g. RE2O3 (RE = Y, Gd, Dy), GdFeO3, Gd3Fe5O12, Na0.5K0.5NbO3, have been prepared by colloidal and sol-gel methods. The sizes of the nanocrystals were in the range 3-15 nm and different carboxylic acids, e.g. oleic or citric acid, were chemisorbed onto the surface of the nanoparticles. From FT-IR measurements it is concluded that the bonding to the surface takes place via the carboxylate group in a bidentate or bridging fashion, with some preference for the latter coordination mode. The magnetic properties of nanocrystalline Gd2O3 and GdFeO3 were measured, both with respect to magnetic resonance relaxivity and magnetic susceptibility. Both types of materials exhibit promising relaxivity properties, and may have the potential for use as positive contrast enhancing agents in magnetic resonance imaging (MRI). The nanocrystalline samples were also characterised by transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and quantum chemical calculations.

Thin films of Na0.5K0.5NbO3, GdFeO3 and Gd3Fe5O12 were prepared by sol-gel methods and characterized by x-ray powder diffraction (XRPD) and scanning electron microscopy (SEM). Under appropriate synthesis conditions, rather pure phase materials could be obtained with grain sizes ranging from 50 to 300 nm. Magnetic measurements in the temperature range 2-350 K indicated that the magnetization of the perovskite phase GdFeO3 can be described as the sum of two contributing terms. One term (mainly) due to the spontaneous magnetic ordering of the iron containing sublattice, and the other a susceptibility term, attributable to the paramagnetic gadolinium sublattice. The two terms yield the relationship M(T)=M0(T)+χ(T)*H for the magnetization. The garnet phase Gd3Fe5O12 is ferrimagnetic and showed a compensation temperature Tcomp ≈ 295 K.

Ort, förlag, år, upplaga, sidor
Institutionen för fysik, kemi och biologi, 2008
Serie
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1182
Nyckelord
nanoparticles, synthesis, contrast agents, functionalization, thin films
Nationell ämneskategori
Kemi
Identifikatorer
urn:nbn:se:liu:diva-11831 (URN)978-91-7393-899-0 (ISBN)
Disputation
2008-06-10, Planck, Fysikhuset, Campus Valla, Linköpings Universitet, Linköping, 10:15 (Engelska)
Opponent
Handledare
Tillgänglig från: 2008-05-21 Skapad: 2008-05-21 Senast uppdaterad: 2021-10-13

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Söderlind, FredrikUvdal, KajsaKäll, Per-Olov

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