Efficient artificial mineralization route to decontaminate Arsenic(III) polluted water -the Tooeleite Way

Increasing exposure to arsenic (As) contaminated ground water is a great threat to humanity. Suitable technology for As immobilization and removal from water, especially for As(III) than As(V), is not available yet. However, it is known that As(III) is more toxic than As(V) and most groundwater aquifers, particularly the Gangetic basin in India, is alarmingly contaminated with it. In search of a viable solution here, we took a cue from the natural mineralization of Tooeleite, a mineral containing Fe(III) and As(III)ions, grown under acidic condition, in presence of SO42- ions. Complying to this natural process, we could grow and separate Tooeleite-like templates from Fe(III) and As(III) containing water at overall circumneutral pH and in absence of SO42- ions by using highly polar Zn-only ends of wurtzite ZnS nanorods as insoluble nano-acidic-surfaces. The central idea here is to exploit these insoluble nano-acidic-surfaces (called as INAS in the manuscript) as nucleation centres for Tooeleite growth while keeping the overall pH of the aqueous media neutral. Therefore, we propose a novel method of artificial mineralization of As(III) by mimicking a natural process at nanoscale

Role of Carbon in Enhancing the Performance of MgB2 superconductor

The enhancement of the critical current density (Jc(H)) of carbon and nano-SiC doped MgB2 is presented and compared. The upper critical field (Hc2) being determined from resistivity under magnetic field experiments is though improved for both C substitution and nano-SiC addition the same is more pronounced for the former. In MgB2-xCx carbon is substituted for boron that induces disorder in the boron network and acts as internal pinning centres. The optimal Jc(H) values are obtained for x = 0.1 sample . In case of nano-SiC doped in MgB2, the Jc(H) improves more profoundly and two simultaneous mechanisms seems responsible to this enhancement. Highly reactive nano-SiC releases free carbon atom, which gets easily incorporated into the MgB2 lattice to act as intrinsic pinning centres. Further enhancement is observed for higher nano-SiC concentrations, where the un-reacted components serve as additional extrinsic pinning centres.Comment: 17 Pages text + Fig

Spectroscopic study of pentacene assembled in Langmuir-Blodgett film mixed with stearic acid

12-16<span style="font-size: 15.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">Langmuir Blodgett (LB) films of non-amphiphilic pentacene mixed with stearic acid have been prepared and its photo-physical properties are reported here. Surface pressure versus area-per-molecule isotherms (π-A) at different compositions are measured. Spectroscopic properties (UV-Visible absorption, emission and Scanning Electron Micrograph) of pentacene in LB film have been reported. The blue-shifted absorption and red shifted emission suggest the formation of H-type of aggregates. </span

Enhancing Performances of Hybrid Perovskite Light Emitting Diodes with Thickness Controlled PMMA Interlayer

status: publishe

Long-Range Visible Fluorescence Tunability Using Component-Modulated Coupled Quantum Dots

A simple route for tailoring emissions in the visible wavelength region by chemically coupling quantum dots composed of ZnSe and CdS is reported. coupled quantum dots offer a novel route for tuning electronic transitions via band-offset engineering at the material interface. This novel class of asymmetric. coupled quantum structures may offer a basis for a diverse set of building blocks for optoelectronic devices, ultrahigh density memories, and quantum information processing

Solution phase synthesis of large-area ultra-thin two dimensional layered Bi2Se3: role of Cu-intercalation and substitution

status: publishe

THE ORIGIN OF FERROMAGNETISM IN Ni-DOPED ZnO AND SnO2

We present a detailed study of the ferromagnetism in nano-Ni-doped SnO2 and ZnO. It is shown that the ferromagnetic behavior is not an intrinsic property of the systems but rather associated with the presence of nNi particles in both matrices. The ferromagnetic transition of all Ni-doped samples is at 631(2) K, the same as the TC value for bulk Ni and nano-Ni powder. The saturation moments of the nano-Ni-doped samples scale with the Ni concentration and are much lower than that of pure Ni. This is due to the large surface area of nano-Ni particles which are partially oxidized due to nano-NiO. 119Sn Mössbauer spectroscopy studies on Sn0.96Ni0.04O2 do not show any transferred hyperfine field on the Sn nuclei, confirming that the magnetic properties stem from a different phase

Shape-Dependent Confinement in Ultrasmall Zero-, One-, and Two-Dimensional PbS Nanostructures

Spatial dimensionality affects the degree of confinement when an electron-hole pair is squeezed from one or more dimensions approaching the bulk exciton Bohr radius (alpha(B)) limit. The etectron-hole interaction in zero-dimensional (0D) dots, one-dimensional (1D) rods/wires, and two-dimensional (2D) wells/sheets should be enhanced by the increase in confinement dimensions in the order 0D > 1D > 2D. We report the controlled synthesis of PbS nanomateriats with 0D, 1D, and 2D forms retaining at least one dimension in the strongly confined regime far below alpha(B) (similar to 10 nm for PbS) and provide evidence through varying the exciton-phonon coupling strength that the degree of confinement is systematically weakened by the loss of confinement dimension. Geometry variations show distinguishable far-field optical polarizations, which could find useful applications in polarization-sensitive devices

Tuning copper sulfide nanosheets by cation exchange reactions to realize two-dimensional CZTS dielectric layers

status: publishe

Fabrication of Highly Stable, Hybrid PbS Nanocomposites in PAMAM Dendrimer Matrix for Photodetection

A novel dendrimer-templating one step method for the in situ synthesis of hybrid nanocomposites of lead sulfide (PbS) quantum dots (QDs) of average diameter of 2.5–4.5 nm in poly­(amidoamine) dendrimer matrix (PAMAM) at ambient condition is reported here. The PbS QDs are developed in cubic crystallographic phase with a high degree of crystallinity. FTIR analysis confirm a direct evidence of PbS QDs linkage to the surface functional groups of dendrimer molecules, which provides a way to prevent the aggregation tendency of the PbS QDs retaining the original properties in 3D rigid dendrimer matrix. Additionally, the thermal stability of dendrimer molecule increases in the nanocomposite unit indicating strong interaction of inorganic phases with dendrimer. The as-prepared PbS nanocomposites could be stored for three months at 4 °C retaining original optical characteristics. The synthesis route provides a simplified colloidal route for producing monodisperse hybrid PbS nanocomposites with robust optical properties. Pure dendrimer is photo inactive, while upon white light irradiation, the PbS nanocomposites results in enhanced photocurrent compared to the dark measurement. Repetitive on–off device response upon white light illumination is found to be sharp and repeatable over successive on/off irradiation cycles. The photoresponse of PbS nanocomposites promises application in photoswitching and photosensitive detectors