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Sol–gel synthesis and characterization of Na0.5K0.5NbO3 thin films
Linköping University, Department of Physics, Chemistry and Biology, Inorganic Chemistry. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Physical Chemistry. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-1744-7322
2005 (English)In: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 281, no 2-4, 468-474 p.Article in journal (Refereed) Published
Abstract [en]

Thin films of the perovskite structured Na0.5K0.5NbO3 (NKN) have been synthesized with three different sol–gel methods, viz. the alkoxide method, a modified Pechini method and a somewhat novel oxalate method, based on 2-methoxy ethanol as solvent with oxalic acid and ethylene glycol as chelating ligand and stabilizer. Only one method (the modified Pechini method) gave pure NKN phase while the other two methods gave extra peaks in the X-ray diffraction patterns, indicating that other, unidentified, phases were present. SEM images revealed grain sizes ranging from 100 to 300 nm.

Place, publisher, year, edition, pages
2005. Vol. 281, no 2-4, 468-474 p.
Keyword [en]
Characterization; Chemical solution deposition processes; Niobates; Dielectric materials
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-13299DOI: 10.1016/j.jcrysgro.2005.04.044ISI: 000231011600038OAI: oai:DiVA.org:liu-13299DiVA: diva2:18248
Available from: 2008-05-21 Created: 2008-05-21 Last updated: 2017-12-13
In thesis
1. Colloidal synthesis of metal oxide nanocrystals and thin films
Open this publication in new window or tab >>Colloidal synthesis of metal oxide nanocrystals and thin films
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2008
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1182
Keyword
nanoparticles, synthesis, contrast agents, functionalization, thin films
National Category
Chemical Sciences
Identifiers
urn:nbn:se:liu:diva-11831 (URN)978-91-7393-899-0 (ISBN)
Public defence
2008-06-10, Planck, Fysikhuset, Campus Valla, Linköpings Universitet, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2008-05-21 Created: 2008-05-21 Last updated: 2009-05-15
2. Colloidal Synthesis and Characterisation of (a) Na0.5K0.5NbO3 Thin Films; and (b) Functionalised Gd2O3 Nanocrystals
Open this publication in new window or tab >>Colloidal Synthesis and Characterisation of (a) Na0.5K0.5NbO3 Thin Films; and (b) Functionalised Gd2O3 Nanocrystals
2004 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

(a) Thin films of the perovskite structured Na0.5K0.5NbO3 (NKN) have been synthesised with several different sol-gel methods. Only one method gave pure NKN phase while the other methods gave extra peaks in the x-ray diffraction patterns, indicating that other, unidentified, phases were present. Scanning electron microscopy revealed grain sizes ranging from about 50 to 300 nm. The films prepared by chemical methods are compared with sputtered thin films.

(b) Nanocrystals of Gd2O3 have been prepared by various methods, using e.g. trioctylphosphine oxide (TOPO), diethylene glycol (DEG). The crystalline particles were of sizes 5 to 15 nm. Onto the surface of the particles, made with DEG, different carboxylic acids e.g. oleic acid or citric acid etc, were adsorbed. From IR measurements the bonding to the surface is recognised as chemisorbed via the carboxylate group in a bidentate or bridging fashion, with preference for the bridging coordination. The organic acid-particle complexes were characterised by XRPD, TEM, FTIR, Raman and XPS.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2004. 71 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1115
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-54128 (URN)LiU-TEK-LIC-2004:44 (Local ID)91-8529-531-0 (ISBN)LiU-TEK-LIC-2004:44 (Archive number)LiU-TEK-LIC-2004:44 (OAI)
Presentation
(English)
Opponent
Supervisors
Available from: 2010-02-25 Created: 2010-02-24 Last updated: 2013-11-14Bibliographically approved

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Söderlind, FredrikKäll, Per-OlovHelmersson, Ulf

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