Search results for "nanoparticle"

Room-temperature electrical addressing of a bistable spin-crossover molecular system.

2011

Dynamics of nanoparticles in a supercooled liquid

2008

The dynamic properties of nanoparticles suspended in a supercooled glass forming liquid are studied by x-ray photon correlation spectroscopy. While at high temperatures the particles undergo Brownian motion the measurements closer to the glass transition indicate hyperdiffusive behavior. In this state the dynamics is independent of the local structural arrangement of nanoparticles, suggesting a cooperative behavior governed by the near-vitreous solvent.

Spintronics and Nanomemory Systems

2017

The chapter presents and explains the possibilities of CNT forest growth on Fe–Pt nanoparticles for the magnetic nanomemory. The magnetoresistance phenomena – giant magnetoresistance and tunnelling magnetoresistance (GMR and TMR) – for nanomemory devices are based on CNTs of various morphologies (i.e. various chiralities, diameters). It includes metal- and semiconductor-like CNTs which can be considered as alternative variants for electromagnetic nanosensoring and magnetic nanomemory. The chapter also presents simulations of Fe–Pt magnetically disordered nanodrops, as well as spin transport models.

Neutron scattering study of structural and magnetic size effects in NiO

2013

Nickel oxide powders with the grain size of 13–1500 nm have been studied by neutron scattering, scanning electron microscopy and vibrating sample magnetometry. We have found that the atomic structure and the antiferromagnetic ordering are nearly independent of the average size of grains. The existence of the uncompensated spins in nanoparticles with the grain size below 100 nm has been detected.

Thermal fluctuations and longitudinal relaxation of single-domain magnetic particles at elevated temperatures

2004

We present numerical and analytical results for the swiching times of magnetic nanoparticles with uniaxial anisotropy at elevated temperatures, including the vicinity of T_c. The consideration is based in the Landau-Lifshitz-Bloch equation that includes the relaxation of the magnetization magnitude M. The resulting switching times are shorter than those following from the naive Landau-Lifshitz equation due to (i) additional barrier lowering because of the reduction of M at the barrier and (ii) critical divergence of the damping parameters.

PEDOT thin films with n-type thermopower

2019

peer-reviewed Synthesis of n-type organic semiconductors is challenging as reduced states are difficult to obtain due to their instability in air. Here, we report tailoring of semiconducting behavior through control of surfactant concentration during synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles. Nanoparticles were synthesized by mini-emulsion polymerization, where stable suspensions were used to produce polymer films by a simple casting technique on polyethylene terephthalate (PET) substrates. Electrical conductivity and Seebeck coefficients were measured as a function of surfactant concentration. It was found that conductivity decreases three orders of magnitude as s…

Cytotoxicity of Metal and Semiconductor Nanoparticles Indicated by Cellular Micromotility

2009

In the growing field of nanotechnology, there is an urgent need to sensitively determine the toxicity of nanoparticles since many technical and medical applications are based on controlled exposure to particles, that is, as contrast agents or for drug delivery. Before the in vivo implementation, in vitro cell experiments are required to achieve a detailed knowledge of toxicity and biodegradation as a function of the nanoparticles' physical and chemical properties. In this study, we show that the micromotility of animal cells as monitored by electrical cell-substrate impedance analysis (ECIS) is highly suitable to quantify in vitro cytotoxicity of semiconductor quantum dots and gold nanorods…

Synthesis of Multifunctional Inorganic Materials

2018

Abstract Both, novel and older widely and routinely used methods of chemical synthesis fornew multifunctional inorganic (nano) materials with different sizes and morphologies are reviewed and summarized in this chapter. Illustrative examples of micro- and nanoparticle preparations are provided regarding different applications: renewable and sustainable energy harvesting, water splitting and hydrogen generation, fuel and solar cell devices, luminescent materials for white light–emitting diodes and clean environment. We give our perspective on the current status of the topic: methods of colloidal chemistry, coprecipitation, reverse-micelle technique, sol–gel, spray pyrolysis, microwave-assist…

Magnetic polyorganosiloxane core–shell nanoparticles: Synthesis, characterization and magnetic fractionation

2010

Abstact Here, we present the synthesis, characterization and magnetic separation of magnetic polyorganosiloxane nanoparticles. Magnetic iron oxide nanoparticles with average particle radii of 3.2 nm had been synthesized by a simple coprecipitation process of iron(II) and iron(III) salt in basic solution. Afterwards, the particles were successfully incorporated into a polyorganosiloxane network via a polycondensation reaction of trimethoxymethylsilane (T), diethoxydimethylsilane (D) and the functional monomer (chloromethylphenyl)trimethoxysilane (ClBz-T) in aqueous dispersion. A core–shell system was chosen to increase the flexibility of the system concerning size, composition and functional…

Optical Properties of Assemblies of Molecules and Nanoparticles

2013

Organic dye molecules, colloidal semiconductor quantum dots, and light-harvesting complexes have been employed as optically active building blocks to create complex molecular assemblies via covalent and non-covalent interactions. Taking advantage of the chemical flexibility of the dye and quantum dot components, as well as recombinant protein expression and the ordering capability of cholesteric phases, specific optical function could be implemented. Photophysical phenomena that have been addressed include light-harvesting, electronic excitation energy transfer (EET), and lasing. Optical single-molecule experiments allow control of energy transfer processes in individual molecular dyads and…