Papers by Muhammet Toprak
Nanotechnology, Jan 1, 2009
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Journal of nanoscience and nanotechnology, Jan 1, 2009
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Journal of nanoscience and nanotechnology, Jan 1, 2010
A novel synthesis approach based on a solution route has been developed for the fabrication of na... more A novel synthesis approach based on a solution route has been developed for the fabrication of nanocrystalline bismuth telluride. The method consists of dissolving both bismuth and tellurium into the same organic solvent with the assistance of complexing agents and one-step coprecipitation of bismuth telluride. The synthesized nanocrystalline bismuth telluride powders possess rhombohedral crystal structure and are nanosheet/nanorod-like with an average size of between 30 and 40 nm. The thermal conductivity of the hot-pressed compact consolidated from the as-synthesized nanopowders is 0.39-0.45 Wm(-1)K(-1) in the temperature range of 323 to 523 K, which is at most one third of that of bulk bismuth telluride-based materials reported in the literature. Such low thermal conductivity of the investigated bismuth telluride is mainly attributed to substantially high concentration of grain boundaries provided by nanostructuring to scatter phonons intensively.
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Nanotechnology, Jan 1, 2011
Synthesis of colloidal nanocrystals of II-VI semiconductor materials has been refined in recent d... more Synthesis of colloidal nanocrystals of II-VI semiconductor materials has been refined in recent decades and their size dependent optoelectronic properties have been well established. Here we report a facile synthesis of CdSe-CdS core-shell heterostructures using a two-step hot injection process. Red-shifts in absorption and photoluminescence spectra show that the obtained quantum dots have quasi-type-II alignment of energy levels. The obtained nanocrystals have a heterostructure with a large and highly faceted tetrahedral CdS shell grown epitaxially over a spherical CdSe core. The obtained morphology as well as high resolution electron microscopy confirms that the tetrahedral shell have a zinc blende crystal structure. A phenomenological mechanism for the growth and morphology of the nanocrystals is discussed.
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Contrast media & molecular imaging
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Central European Journal of …, Jan 1, 2009
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… European Journal of …, Jan 1, 2011
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Russian Journal of …, Jan 1, 2010
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Materials Research …, Jan 1, 2010
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… of nanoscience and …, Jan 1, 2011
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International Journal of …, Jan 1, 2011
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Journal of the …, Jan 1, 2010
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Journal of nanoparticle …, Jan 1, 2011
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… (INEC), 2011 IEEE …, Jan 1, 2011
Page 1. ZnO nanorods/nanoflowers and their applications David B. Rihtnesberg, Susanne Almqvist an... more Page 1. ZnO nanorods/nanoflowers and their applications David B. Rihtnesberg, Susanne Almqvist and Qin Wang* Department of Nanoelectronics Acreo AB Stockholm, Sweden *qin.wang@acreo.se Abhilash Sugunan, Xuran ...
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Solid State …, Jan 1, 2004
Page 1. Polymeric Nanocomposites of Complex Ferrite Do-Kyung Kim 1 , Muhammet S. Toprak 1 , Maria... more Page 1. Polymeric Nanocomposites of Complex Ferrite Do-Kyung Kim 1 , Muhammet S. Toprak 1 , Maria Mikhaylova 1 , Yun-Suk Jo 1 , Steven J. Savage 2 , Hyung Bock Lee 3 , Thomas Tsakalakos 4 and Mamoun Muhammed 2 ...
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Nano reviews, Jan 1, 2010
This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles ... more This article provides an up-to-date review on nanocomposites composed of inorganic nanoparticles and the polymer matrix for optical and magnetic applications. Optical or magnetic characteristics can change upon the decrease of particle sizes to very small dimensions, which are, in general, of major interest in the area of nanocomposite materials. The use of inorganic nanoparticles into the polymer matrix can provide high-performance novel materials that find applications in many industrial fields. With this respect, frequently considered features are optical properties such as light absorption (UV and color), and the extent of light scattering or, in the case of metal particles, photoluminescence, dichroism, and so on, and magnetic properties such as superparamagnetism, electromagnetic wave absorption, and electromagnetic interference shielding. A general introduction, definition, and historical development of polymer–inorganic nanocomposites as well as a comprehensive review of synthetic techniques for polymer–inorganic nanocomposites will be given. Future possibilities for the development of nanocomposites for optical and magnetic applications are also introduced. It is expected that the use of new functional inorganic nano-fillers will lead to new polymer–inorganic nanocomposites with unique combinations of material properties. By careful selection of synthetic techniques and understanding/exploiting the unique physics of the polymeric nanocomposites in such materials, novel functional polymer–inorganic nanocomposites can be designed and fabricated for new interesting applications such as optoelectronic and magneto-optic applications.
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Journal of Nanoparticle Research, Jan 1, 2010
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Journal of Materials Chemistry, Jan 1, 2010
... Abhilash Sugunana, S. Hassan M. Jafrib, Jian Qina, Tobias Blomb, Muhammet S. Topraka, Klaus .... more ... Abhilash Sugunana, S. Hassan M. Jafrib, Jian Qina, Tobias Blomb, Muhammet S. Topraka, Klaus ... 2, VI Klimov, AA Mikhailovsky, S. Xu, A. Malko, JA Hollingsworth, CA Leatherdale, H. -J. Eisler and MG Bawendi, Science, 2000, 290, 314 Article ChemPort ; RAM Hikmet, PTK ...
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Novel chemical alloying approach has been developed for the fabrication of nanocrystalline Co1-xN... more Novel chemical alloying approach has been developed for the fabrication of nanocrystalline Co1-xNixSb3-yTey skutterudites. The approach has compromised solution chemical synthesis and thermochemical processing under controlled conditions. All of the required elements, Co, Ni, Sb and Te were coprecipitated from an aqueous solution of their salts to produce a precursor with a well-defined composition, fine particle size, high homogeneity, low crystallinity and high reactivity. After calcination and hydrogen reduction of the precursor at moderate temperature of 450°C for 2 hrs, these elements were alloyed into Co1-xNixSb3-yTey skutterudite of high purity and nano-grain size. These nanocrystalline materials have demonstrated very low thermal conductivities and enhanced thermoelectric performance. Thermal conductivity values of skutterudite have been reduced by 25-75% over polycrystalline materials. With a combined doping by Ni and Te, a ZT value of 0.65 at 700 K has been obtained for the sample of Co0.92Ni0.08Sb2.988Te0.012.
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Journal of Materials …, Jan 1, 2012
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Papers by Muhammet Toprak