Coaxial Nickel Poly(Vinylidene Fluoride Trifluoroethylene) Nanowires for Magnetoelectric Applications

Magnetoelectric (ME) composite materials, in which the coupling between magnetostricitve and piezoelectric effects is achieved, are potential candidates for multifunctional devices where the interplay between electrical, magnetic and mechanical properties of these structures can be fully exploited. Nanostructured composites are particularly interesting due to the enhancement of ME coupling expected at the nanoscale. However, direct studies of ME coupling in nanocomposites by scanning probe techniques are rare due to the complex interplay of forces at play, including those arising from electrostatic, magnetic and electromechanical interactions. In this work, the ME coupling of coaxial nickel - polyvinylidene fluoride trifluoroethylene [Ni-P(VDF-TrFE)] composite nanowires, fabricated by a scalable template-wetting based technique, is studied using a systematic sequence of scanning probe techniques. Individual ME nanowires were subjected to an electric field sufficient for ferroelectric poling in piezo-response force microscopy (PFM) mode, while magnetic force microscopy (MFM) was used to measure localised changes in magnetization as a result of electrical poling. Kelvin probe force microscopy (KPFM) measurements of surface potential were conducted to eliminate for the effect of contact potential differences during these measurements. An inverse, static, magnetoelectric coupling coefficient of ~1 x 10-11 s m-1 was found in our coaxial nanocomposite nanowires, comparable to other types of planar composites studied in this work, despite having an inferior piezoelectric-to-magnetostrictive volume ratio. The efficient ME coupling in our coaxial nanowires is attributed to the larger surface-to-volume interfacial contact between Ni and P(VDF-TrFE), and is promising for future integration into ME composite devices such as magnetic field sensors or energy harvesters

Mapping piezoelectric response in nanomaterials using a dedicated non-destructive scanning probe technique

There has been tremendous interest in piezoelectricity at the nanoscale, for example in nanowires and nanofibers where piezoelectric properties may be enhanced or controllably tuned, thus necessitating robust characterization techniques of piezoelectric response in nanomaterials. Piezo-response force microscopy (PFM) is a well-established scanning probe technique routinely used to image piezoelectric/ferroelectric domains in thin films, however, its applicability to nanoscale objects is limited due to the requirement for physical contact with an atomic force microscope (AFM) tip that may cause dislocation or damage, particularly to soft materials, during scanning. Here we report a non-destructive PFM (ND-PFM) technique wherein the tip is oscillated into “discontinuous” contact during scanning, while applying an AC bias between tip and sample and extracting the piezoelectric response for each contact point by monitoring the resulting localized deformation at the AC frequency. ND-PFM is successfully applied to soft polymeric (poly-L-lactic acid) nanowires, as well as hard ceramic (barium zirconate titanate–barium calcium titanate) nanowires, both previously inaccessible by conventional PFM. Our ND-PFM technique is versatile and compatible with commercial AFMs, and can be used to correlate piezoelectric properties of nanomaterials with their microstructural features thus overcoming key characterisation challenges in the field

Bright white light emission from In<SUB>2</SUB>S<SUB>3</SUB> : Eu<SUP>3+</SUP>nanoparticles

Here, we report the bright white light emission from Eu<SUP>3+</SUP> doped In<SUB>2</SUB>S<SUB>3</SUB> nanoparticles by single wavelength light excitation (350 nm). The energy transfer (ET) from the In<SUB>2</SUB>S<SUB>3</SUB> host to the Eu<SUP>3+</SUP> ions is studied by steady-state and time-resolved spectroscopy. It is found that the ET efficiency from In<SUB>2</SUB>S<SUB>3</SUB> nanoparticles to Eu<SUP>3+</SUP> increases from 0.27% to 0.42% with increasing dopant concentration. The calculated quantum efficiency is 24.2% for 1.0 mol% Eu doped In<SUB>2</SUB>S<SUB>3</SUB> nanoparticle and the CIE coordinates are 0.27 and 0.29, which fall within the white region of the 1931 CIE diagram

Cds:Mn Nanorods: Solvothermal Synthesis And Properties

Manganese (0.05-9 mol.%) doped CdS nanorods were synthesized via solvothermal route using ethylenediamine (En) and a mixture of En and water as the solvents. The diameters and the lengths of the doped CdS nanorods varied from 40-100 nm and 600-2500 nm, respectively, with change in the composition of the solvents. The broad photoluminescence (PL) emission from the undoped CdS nanorods centered at ∼535 nm is found to be blue shifted to 516 nm with the incorporation of Mn in the CdS crystal structure. Also increase in the intensity of the PL was noticed in the Mn doped CdS nanorods for both the solvent systems. Maximum PL intensity was observed for 1 mol.% Mn in case of En system and for 0.5 mol.% Mn in case of En/water system, above which quenching occurred as a result of Mn-Mn clustering. EPR study revealed six-line hyperfine splitting for low Mn concentration in both solvent systems. Increase in the Mn concentration caused EPR signal broadening due to Mn-Mn clustering. Copyright © 2008 American Scientific Publishers All rights reserved

Multicolor Luminescence From Transition Metal Ion (Mn \u3csup\u3e2+\u3c/sup\u3e And Cu \u3csup\u3e2+\u3c/sup\u3e) Doped Zns Nanoparticles

Mn and Cu doped ZnS nanoparticles in powder form were prepared by a simple solvothermal route. Particle size and crystal structure of the products were investigated through X-ray diffraction study revealing the formation of cubic ZnS nanoparticles of average diameter 2.5 nm. Particle size was also verified by the high resolution transmission electron microscopic images. Blue emission at ∼445 nm was observed from the undoped sample, which was attributed to the presence of large surface defects. With increasing doping concentration the defect related emission gradually quenches and subsequently the impurity related emissions appeared. Mn doped samples exhibited orange emission at ∼580 nm which may be attributed to the transition between 4T 1 and 6A 1 energy levels of the Mn 2+ 3d states. Whereas, the Cu doped ZnS nanoparticles exhibited a red shifted strong blue emission at ∼466 nm which is attributed to the transition of the electrons from the surface states to the \u27t 2\u27 levels of Cu impurities. Copyright © 2007 American Scientific Publishers All rights reserved

Research data supporting Coaxial Nickel-Poly (Vinylidene Fluoride Trifluoroethylene) Nanowires for Magnetoelectric Applications

These are vibrating sample magnetometry (VSM) measurement results for the different samples examined in the corresponding pape

Growth, optical, and electrical properties of In<SUB>2</SUB>S<SUB>3</SUB> zigzag nanowires

Ultralong In2S3 zigzag nanowires (diameter ∼66 nm) of variable periodicities are fabricated by physical vapor deposition of indium and sulfur, using Au as the catalyst element. The morphologies of the zigzag nanowires are controlled by interplay of surface free energy minimization and self-stacking of the closest-packed (103) and (0012) planes along their axis. The resulting zigzag nanowires show an enhanced luminescence and a rectifying behavior, which can open up avenues for a host of potential device applications