Production and characterization of maghemite nanoparticles

Baltacı, Özge Acarbaş
The aim of this study is to produce maghemite nanoparticles by using different production methods. To achieve this purpose Sol-Gel Processing and Microwave Synthesis methods were employed. Suitable characterization techniques like XRD, TEM, BET, and VSM were performed to control the properties of the synthesized particles whether they are suitable for certain applications. In the sol-gel part of the study two different routes were employed to obtain maghemite nanoparticles. In the first route TEOS (tetraethoxysilane) was used as the precursor. Approximate particle sizes of these samples lie between 12.0-23.4 nm. From the magnetization measurements saturation magnetization (Ms) values are obtained between 4-12 emu/g. In the second route of the sol-gel method ethylene glycol and diethylene glycol were used as starting materials. Ms value was found as 28 emu/g for the ethylene glycol sample as the highest magnetization value due to having the highest amount of maghemite phase. The superparamagnetic behavior observed in these samples was tried to explain by curve fitting. Langevin and tangent hyperbolic functions were used to fit the magnetization curves. From the XRD study particle sizes of these samples lie in the 4.0-48.5 nm range and these results are consistent with the size distributions obtained from the TEM study. In the last part of the study microwave method was used to produce maghemite nanoparticles. Most of the samples contain maghemite and hematite phases together and particle sizes were between 3-30 nm. Ms values of these microwave samples were lower than that of the sol-gel samples with a value about 3.0 emu/g. Keywords: Maghemite, nanoparticle, superparamagnetism, sol-gel, microwave.


Fabrication and characterization of copper oxide-silicon nanowire heterojunction photodiodes
AKGÜL, GÜVENÇ; AKSOY, FUNDA; Mulazimoglu, Emre; Ünalan, Hüsnü Emrah; Turan, Raşit (IOP Publishing, 2014-02-12)
In this study, copper oxide (CuO) thin film/silicon (Si) nanowire heterojunctions have been fabricated and their optoelectronic performances have been investigated. Vertically aligned n-type Si nanowires have been fabricated using metal-assisted etching (MAE) technique. CuO thin films were synthesized by the sol-gel method and deposited onto the nanowires through spin-coating. Fabricated nanowire heterojunction devices exhibited excellent diode behaviour compared to the planar heterojunction control device....
Production and structural characterization of iron-boron nanoalloys
Fadaie, Amir; Mekhrabov, Amdulla O.; Akdeniz, Mahmut Vedat; Department of Metallurgical and Materials Engineering (2014)
The purpose of this study was production and structural characterization of Fe-B crystalline /amorphous nanocomposite powders. In the theoretical part of the study, detailed nanoscale structures of Fe80B20 and Fe85B15 metallic glasses were investigated using Molecular Dynamics (MD) method as well as several structural analysis tools. In the experimental part of the study, Fe80B20 and Fe85B15 crystalline /amorphous nanocomposite powders have been synthesized by using surfactant-assisted high-energy ball mill...
Development of novel pea flour-based nanofibres by electrospinning method
Oğuz, Seren; Aydogdu, AYÇA; Şümnü, Servet Gülüm; Şahin, Serpil (Wiley, 2018-05-01)
The aim of this study was to produce pea flour and hydroxypropyl methylcellulose (HPMC)-based novel nanofibres using electrospinning method. The effects of pH, pea flour and HPMC concentration on apparent viscosity, electrical conductivity of electrospinning solutions and nanofibre characteristics were studied. Solutions were prepared at different pH values (7, 10, 12), with different pea flour concentrations (1%, 2% w/v) and HPMC concentrations (0.25%, 0.5%, 1.0% w/v). For all pea flour concentrations, k v...
Characterization of thermoluminescence kinetic parameters of beta irradiated B doped Ca-5(PO4)(3)OH powder obtained from eggshell
Depci, T.; Oglakci, M.; Sezer, Selda; YÜCEL, AYTAÇ; DOĞAN, TAMER; Souadi, G.; TOPAKSU, MUSTAFA; Can, N. (2021-07-01)
In this study, we have synthesized B doped Ca5(PO4)3OH (HAP) by a sonication chemical method. The thermoluminescence (TL) properties of the family of synthesized samples (B doped Ca5(PO4)3OH (HAP) were investigated using an IRSL-TL 565 nm filter. This gave the highest TL intensity of each phosphor after 2 Gy beta-irradiation. Three TL glow peaks of B doped Ca5(PO4)3OH (HAP) are centered at around 84, 208 and 324 degrees C (with a heating rate of 2 degrees Cs-1). The trapping parameters such as activation en...
Preparation and characterization of W/O/W type double emulsion containing PGPR-lecithin mixture as lipophilic surfactant
ALTUNTAS, Ozlem Yuce; Şümnü, Servet Gülüm; Şahin, Serpil (Informa UK Limited, 2017-01-01)
The objective of this study is to produce double emulsion by combining polyglycerol polyricinoleate (PGPR) with lecithin as lipophilic surfactant. Although lecithin alone produced only oil-in-water type emulsion, the mixture of lecithin and PGPR could produce water-in-oil type emulsion as well. Moreover, different emulsification treatments were applied to study the influence of homogenization methods on the physicochemical characteristics. The obtained double emulsions were compared in terms of stability an...
Citation Formats
Ö. A. Baltacı, “Production and characterization of maghemite nanoparticles,” Ph.D. - Doctoral Program, Middle East Technical University, 2010.