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Synthesis and characterisation of Gd2O3 nanocrystals functionalised by organic acids
Linköpings universitet, Institutionen för fysik, kemi och biologi, Oorganisk Kemi. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.ORCID-id: 0000-0002-7171-5383
Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensorvetenskap och Molekylfysik. Linköpings universitet, Tekniska högskolan.
Linköpings universitet, Institutionen för fysik, kemi och biologi, Fysikalisk Kemi. Linköpings universitet, Tekniska högskolan.
Visa övriga samt affilieringar
2005 (Engelska)Ingår i: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 288, nr 1, s. 140-148Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Nanocrystals of Gd2O3 have been prepared by various methods, using, e.g., trioctylphosphine oxide (TOPO), diethylene glycol (DEG) or glycine. The crystalline particles were of sizes 5 to 15 nm. Different carboxylic acids, e.g., oleic acid or citric acid, were adsorbed onto the surface of the particles made with DEG. IR measurements show that the molecules coordinate to the Gd2O3 surface via the carboxylate group in a bidentate or bridging manner. The organic-acid/particle complexes were characterised by XRPD, TEM, FTIR, Raman, and XPS.

Ort, förlag, år, upplaga, sidor
2005. Vol. 288, nr 1, s. 140-148
Nyckelord [en]
Nanocrystals; Synthesis; Functionalisation; IR; XPS
Nationell ämneskategori
Naturvetenskap
Identifikatorer
URN: urn:nbn:se:liu:diva-13295DOI: 10.1016/j.jcis.2005.02.089ISI: 000229861600019OAI: oai:DiVA.org:liu-13295DiVA, id: diva2:18244
Tillgänglig från: 2008-05-21 Skapad: 2008-05-21 Senast uppdaterad: 2017-12-13
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: 2009-05-15
2. Colloidal Synthesis and Characterisation of (a) Na0.5K0.5NbO3 Thin Films; and (b) Functionalised Gd2O3 Nanocrystals
Öppna denna publikation i ny flik eller fönster >>Colloidal Synthesis and Characterisation of (a) Na0.5K0.5NbO3 Thin Films; and (b) Functionalised Gd2O3 Nanocrystals
2004 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2004. s. 71
Serie
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1115
Nationell ämneskategori
Naturvetenskap
Identifikatorer
urn:nbn:se:liu:diva-54128 (URN)LiU-TEK-LIC-2004:44 (Lokalt ID)91-8529-531-0 (ISBN)LiU-TEK-LIC-2004:44 (Arkivnummer)LiU-TEK-LIC-2004:44 (OAI)
Presentation
(Engelska)
Opponent
Handledare
Tillgänglig från: 2010-02-25 Skapad: 2010-02-24 Senast uppdaterad: 2013-11-14Bibliografiskt granskad
3. Experimental and quantum-chemical studies of the surface interactions between organic molecules and nanocrystals of (a) RE2O3 (RE = Y or Gd); and (b) TiOb2
Öppna denna publikation i ny flik eller fönster >>Experimental and quantum-chemical studies of the surface interactions between organic molecules and nanocrystals of (a) RE2O3 (RE = Y or Gd); and (b) TiOb2
2005 (Engelska)Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The increasing interest for using nanocrystals in bio-medical and optical applications has highlighted the need of molecular functionalisation of nanocrystals. Knowledge of how to attach molecules to the nanocrystal surface is a key factor. This thesis focuses on the surface interactions between nanocrystals of (a) RE2O3 (RE = Y or Gd); and (b) TiO2 and organic molecules, which have been studied experimentally and by quantum-chemical calculations with the intent to elucidate the chemisorption characteristics such as adsorption geometries and energies.

(a) RE2O3 nanocrystal synthesis was performed by a colloidal method based on polyols and by a rapid combustion method. The products were experimentally characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), infrared spectroscopy (IR), Raman, and X-ray photoelectron spectroscopy (XPS). By quantum chemical calculations the chemisorption of formic acid, DEG, water and TMOS at the surface of RE12O18 clusters was studied. From comparison between calculated and experimental vibrational spectra, the binding mode for formic acid on RE2O3 was inferred to be of bridge or bidentate type. XPS and IR showed that DEG chemisorbs on the particle surface and experimental IR spectra of DEG chemisorbed on RE2O3 were consistent with an adsorption mode where the hydroxyl groups are deprotonated according to the quantum-chemical computations.

(b) Synthesis of single-phase rutile TiO2 nanocrystals was done by a sol-gel method and the nanocrystals was subsequently functionalized by organic acids and glycine. Quantum-chemical studies indicate that formic- and acetic acid adsorbs in a bridge or monodentate binding mode, while glycine is suggested to adsorb as a zwitterion with bridge bonded carboxylic group and a hydrogen bonded amino group. However, spectroscopic data showed that the amino acid, unlike the other acids did not adsorb on TiO2 under the given experimental conditions.

Ort, förlag, år, upplaga, sidor
Linköping: Linköpings universitet, 2005. s. 67
Serie
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1198
Nationell ämneskategori
Oorganisk kemi Fysikalisk kemi
Identifikatorer
urn:nbn:se:liu:diva-29720 (URN)LiU-TEK-LIC-2005:53 (Lokalt ID)91-85457-33-7 (ISBN)LiU-TEK-LIC-2005:53 (Arkivnummer)LiU-TEK-LIC-2005:53 (OAI)
Presentation
(Engelska)
Opponent
Handledare
Tillgänglig från: 2009-10-09 Skapad: 2009-10-09 Senast uppdaterad: 2015-03-11Bibliografiskt granskad

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