Search results for "Hysteresi"
showing 10 items of 250 documents
Slow Magnetization Relaxation in a 1-D Double-Chain Coordination Polymer Composed of {Dy<sup>III</sup> <sub>4</sub>} Repeatin…
2013
The "unsuccessful" synthesis of the non-commercially available 'Dy(O2CPh)3' precursor from the stoichiomet- ric reaction of Dy(NO3)3·5H2O with 3 equivalents of NaO2CPh in MeCN/H2O has led instead to the "successful" isolation and structural characterization of the 1-D coordination polymer (Dy4(O2CPh)12(H2O)8)n·2n(PhCO2H)·n(MeCN) (1·2n(PhCO2H)·n(MeCN)) in excellent yields (~90%). The one-dimensional double-chain structure of 1 was resulted from the linkage of two parallel chains by syn,anti-� 1 :� 1 :μ PhCO2 - groups. The lattice structure of 1 is further extended to a 2-D network through hydrogen bonding and - stacking interactions. The observation of out-of-phase (� �� M) ac susceptibility…
Recombination in Perovskite Solar Cells
2017
Trap-assisted recombination, despite being lower as compared with traditional inorganic solar cells, is still the dominant recombination mechanism in perovskite solar cells (PSCs) and limits their efficiency. We investigate the attributes of the primary trap assisted recombination channels (grain boundaries and interfaces) and their correlation to defect ions in PSCs. We achieve this by using a validated device model to fit the simulations to the experimental data of efficient vacuum-deposited p-i-n and n-i-p CH3NH3PbI3 solar cells, including the light intensity dependence of the open circuit voltage and fill factor. We find that, despite the presence of traps at interfaces and grain bounda…
Synthesis and Magnetic Properties of FePt@MnO Nano-heteroparticles
2012
Monodisperse FePt@MnO nano-heteroparticles with different sizes and morphologies were prepared by a seed-mediated nucleation and growth technique. Both size and morphology of the individual domains could be controlled by adjustment of the synthetic parameters. As a consequence, different particle constructs, including dimers, dumbbell-like particles, and flowerlike particles, could be obtained by changing the polarity of the solvent. The FePt@MnO nano-heteroparticles were thoroughly characterized by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analyses and superconducting quantum interference device (SQUID) magnetometry. Due to a sufficient lattice m…
Magneto-optical Investigations of Nanostructured Materials Based on Single Molecule Magnets Monitor Strong Environmental Effects
2007
The determination of the magnetic properties of molecular magnets in environments similar to those used in spintronic devices is fundamental for the development of applications. Single-molecule magnets (SMMs) are molecular cluster systems that display magnetic hysteresis of dynamical origin at low temperature. As they behave like perfectly monodisperse nanomagnets and show clear macroscopic quantum effects in their magnetic properties, they are extremely appealing candidates for the forthcoming generation of molecular devices: they have been proposed as efficient systems for quantum computation, ultra-high-density magnetic recording media, and molecular spintronic systems. These attractive …
A Magnetostrictive Electric Power Generator for energy harvesting from traffic: Design and experimental verification
2015
In the last decades, the growth in energy demand, the decrease of fossil fuels available in the market and the impact of anthropogenic factors on climate change has given new impulse to research on renewable energy systems, particularly those known as energy harvesting devices (EHDs) [1]. A large number of EHDs have been proposed, using different operating principle [1-4]. Among them, piezoelectric and magnetostrictive seem to be particularly suitable for the application in EHD. In these materials the application of external mechanical stress induces a change in the level of magnetization and therefore an electromotive force (emf) can be generated and collected in order to produce electrica…
Microsphere tensiometry to measure advancing and receding contact angles on individual particles
1999
In this paper, a method to measure the advancing and receding contact angles on individual colloidal spheres is described. For this purpose, the microspheres were attached to atomic force microscope cantilevers. Then the distance to which the microsphere jumps into its equilibrium position at the air-liquid interface of a drop or an air bubble was measured. From these distances the contact angles were calculated. To test the method, experiments were done with silanized silica spheres (4.1 μm in diameter). From the experiments with drops, an advancing contact angle of 101 ± 4° was determined. A receding contact angle of 101 ± 2° was calculated from the jump-in distance into a bubble. Both ex…
Viscoelastic properties of the Achilles tendon in vivo
2013
It has been postulated that human tendons are viscoelastic and their mechanical properties time-dependent. Although Achilles tendon (AT) mechanics are widely reported, there is no consensus about AT viscoelastic properties such as loading rate dependency or hysteresis, in vivo. AT force-elongation characteristics were determined from 14 subjects in an ankle dynamometer at different loading rates using motion capture assisted ultrasonography. AT stiffness and elongation were determined between 10 – 80% of maximum voluntary contraction (MVC) force at fast and slow loading rates. As subjects were unable to consistently match the target unloading rate in the slow condition, AT hysteresis was on…
Smart artificial muscle actuators: Liquid crystal elastomers with integrated temperature feedback
2015
Abstract We present a smart, thermally stimulated liquid crystal elastomer actuator with an integrated heater and temperature sensor based on deformable polyimide wiring technology. Due to optimal thermal contact to the active material, heating from room temperature to the point of maximum contraction takes only 19.6 s; cooling requires only 5.6 s. The integrated temperature sensor allows closed-loop operation and characterize the thermomechanical properties of the material: open-loop positioning precision was found to be better than 45 μm and no inherent drift or hysteresis were observed. The maximum force generated by the actuator was 133 mN, corresponding to 76 kPa of stress. This ultra-…
Structure, micromechanical and magnetic properties of polycarbonate nanocomposites
2013
The current study evaluates the applicability of polycarbonate (PC) for development of magnetic polymer nanocomposites with CoFe2O4 nanofiller, the amount of which was changed from 0 to 5 wt. %. Ethylene-vinyl acetate elastomer in the amount of 10 wt. % was added as toughener. Upon introduction of the magnetic filler a magnetic hysteresis loop was observed: at 5 wt.% of CoFe2O4 saturation magnetization of the nanocomposite was 2,2 emu/g, remanent magnetization was 0,8 emu/g and coercivity is 1200 G. Nanoindentation tests showed that nanofiller-reinforced samples maintain reasonable plasticity characterized by work of plastic indentation, while their modulus and hardness were improved by up …
Resistive switching in microscale anodic titanium dioxide-based memristors
2018
Licence CC BY-NC-ND The potentiality of anodic TiO2 as an oxide material for the realization of resistive switching memory cells has been explored in this paper. Cu/anodic-TiO2/Ti memristors of different sizes, ranging from 1 × 1 μm2 to 10 × 10 μm2 have been fabricated and characterized. The oxide films were grown by anodizing Ti films, using three different process conditions. Measured IV curves have shown similar asymmetric bipolar hysteresis behaviors in all the tested devices, with a gradual switching from the high resistance state to the low resistance state and vice versa, and a R_OFF/R_ON ratio of 80 for the thickest oxide film devices.