Search results for " Synthesis"

Continuous hydrothermal synthesis of nanometric BaZrO3 in supercritical water

2007

Abstract Nanocrystalline barium zirconate (BaZrO 3 ) was synthesized using a hydrothermal synthesis process working in supercritical conditions and in a continuous way. By this method, we succeeded in the continuous and rapid production of nanopowders. As a preliminary work three barium precursors have been investigated: barium hydroxide (Ba(OH) 2 ), barium acetate (Ba(CH 3 COO) 2 ) and barium nitrate (Ba(NO 3 ) 2 ). Two of them (Ba(CH 3 COO) 2 and Ba(NO 3 ) 2 ) led to the pure perovskite phase. Then an experimental design has been conducted in order to determine the influence of the experimental parameters on the crystallinity and the grain size of the final product.

Facile hydrothermal synthesis of crystalline Ta2O5 nanorods, MTaO3 (M = H, Na, K, Rb) nanoparticles, and their photocatalytic behaviour

2014

Alkali metal tantalates are of interest for applications in photocatalysis as well as in high temperature resistance or capacitor dielectric materials. We have synthesized nanosized Ta2O5 rods and MTaO3 cubes (M = Na, K, Rb) hydrothermally and demonstrate the pH dependence of the synthesis of tantalum oxide and tantalate nanoparticles. The morphologies of the nanoparticles range from particle agglomerates in acidic reaction media over rods at neutral pH to tantalate cubes in basic reaction media. Whereas there is no apparent influence of the base cation on the particle morphology, there is a pronounced effect on the particle composition. At high base concentrations cubic tantalate particles…

Determining Magnetite/Maghemite Composition and Core–Shell Nanostructure from Magnetization Curve for Iron Oxide Nanoparticles

2018

Iron oxide magnetic nanoparticles produced by chemical synthesis are usually composed of both magnetite and maghemite phases. Information about the phase composition is typically obtained using Mos...

Structural and optical properties of novel surfactant-coated Yb-TiO2 nanoparticle

2010

Abstract In this paper a novel hybrid approach to synthesise composite nanoparticles is presented. It is based on the laser ablation of a bulk target (Yb) immersed in a reversed micellar solution which contains nanoparticles of a different host material (TiO2 nanoparticles) previously synthesised by chemical method. This approach thus exploits the advantages of the chemical synthesis through reversed micellar solution (size control, nanoparticle stabilisation), and of the laser ablation (‘‘clean’’ synthesis, no side reactions). Central role is played by the microscopic processes controlling the deposition of the ablated Yb atoms onto the surface of TiO2 nanoparticles which actually behave a…

Solvothermal synthesis derived Co-Ga codoped ZnO diluted magnetic degenerated semiconductor nanocrystals

2018

Authors kindly acknowledge to the Estonian Research Council ( PUT1096 , IUT2-25 , PUT735 ), the Estonian Centre of Excellence in Research project “Advanced materials and high-technology devices for sustainable energetics, sensorics and nanoelectronics (TK141), and the financial support of HZB. We are grateful to the staff of BESSY II for the assistance and co-operation during the synchrotron-based measurements.

DNA Block Copolymer Micelles – A Combinatorial Tool for Cancer Nanotechnology

2008

Selective drug targeting of a specific organ or tissue is a challenging task. This holds especially true for chemotherapeutic cancer treatment because most of the available anticancer agents cannot distinguish between cancerous and healthy cells, leading to systemic toxicity and undesirable side effects. One effective approach to address this problem is the application of polymeric nanoparticles equipped with targeting units for tumor-specific delivery. For instance dendrimers, highly branched macromolecules, can be equipped with targeting units as well as with anticancer drugs because of their large number of surface functionalities. Amphiphilic block copolymers, which self-assemble in dil…

In-situ time resolved X-ray diffraction study of the formation of the nanocrystalline NbAl3 phase by mechanically activated self-propagating high-tem…

1999

The mechanically activated self-propagating high-temperature synthesis (MASHS) technique was used to produce a NbAl3 intermetallic compound. This process results from the combination of two steps: a mechanical activation of the Nb 3Al powder mixture which is followed by a self-propagating high-temperature synthesis (SHS) reaction, induced by the exothermal character of the reaction Nb3Al. An original experiment was designed to study in-situ the formation of the NbAl3 phase in the combustion front: time-resolved X-ray diffraction coupled with an infrared imaging technique and a thermocouple measurement were performed to monitor the structural and thermal evolution during the SHS reaction. Ow…

Mechanically Activated Self-Propagating High Temperature Synthesis (MASHS) Applied to the MoSi<sub>2</sub> and FeSi<sub>2</sub&g…

1999

Dense nanostructured materials obtained by spark plasma sintering and field activated pressure assisted synthesis starting from mechanically activate…

2004

The preparation of highly dense bulk materials with a grain size in the range of a few to a few hundreds nanometers is currently the objective of numerous studies. In our research we have achieved a measure of success in this regard by using the methods of mechanically-activated, field-activated, pressure-assisted synthesis, MAFAPAS, which has been patented, and mechanically-activated spark plasma sintering, MASPS. Both methods, which consist of the combination of a mechanical activation step followed by a consolidation step under the simultaneous influence of an electric field and mechanical pressure, have led to the formation of dense nanostructured ceramics, intermetallics, and composite…

Hydrothermal synthesis of nanostructured zirconia materials: Present state and future prospects

2005

Abstract Hydrothermal procedures for the synthesis of zirconia-doped nanocrystalline powders show important advantages from the thermodynamic and kinetic point of view (larger domain stability of solid species, faster kinetics crystallisation) as well as from technological point of view (one-step synthesis process at low temperatures, better control of the crystallisation and grain sizes with possibilities to obtain nanocrystalline materials, versatility, environmental friendly technology). Establishment of the conditions for obtaining ZrO2-doped with different oxides is based on thermodynamic predictions. Kinetic modelling of the hydrothermal synthesis of zirconia nanopowders is presented.…