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Inelastic mean free path (IMFP) of the electron is a very important parameter for quantitative analysis of several electron spectroscopies and transport properties. In spite of being a fundamental material property, its experimental determination is not trivial due to complexity of the various electron scattering processes in matter. In this report, we demonstrate a procedure to determine the IMFP of 300 keV electrons in GaN, using the log-ratio technique where the local specimen thickness needs to be accurately known. The GaN nanorod morphology of the sample used here allows the accurate measurement of thickness by 'thickness map' under EFTEM measurements which enable the site specific determination of IMFP. IMFP for different collection semi angles have also been measured to validate the angular dependence. Our experimental results estimates the IMFP of GaN for 300 keV electrons to be 143 ± 11 nm at no-aperture condition and exhibit a strong inverse angular dependence at smaller collection semi angles (β20 mrad) and a near angular independence at larger collection semi angles (β30 mrad). We discuss these results in the light of three different theoretical models prevalent in the literature.The inelastic mean free path (IMFP) of electrons is defined as the average distance traveled between two successive inelastic collisions by an electron moving with a particular energy in a given material. It is a very fundamental material parameter for surface science and description of electron transport processes in solids. IMFP is particularly useful for quantifying several electron spectroscopies such as Auger electron spectroscopy, X-ray photoelectron spectroscopy, electron energy loss (EEL) spectroscopy and elastic peak electron spectroscopy etc. However, it is difficult to determine IMFP experimentally or theoretically as the interaction process has strong angular dependence that varies with electron energy, density and dielectric properties of the material. Particularly for EEL which is carried out in TEM at using electron with few hundred kilovolts, knowledge of IMFP at those high energies is required. In this report, we demonstrate a general procedure to determine IMFP of 300 keV electrons in Gallium Nitride inside TEM. Single crystalline Gallium Nitride nanorod has just been taken as an example to demonstrate the process. The procedure can be extended to any other materials of both crystalline and amorphous in nature.

A Lithium (Li)‐Selenium (Se)‐alkali activated carbon hybrid cell with a tungsten oxide interlayer is implemented for the first time. The Se hybrid at a Se loading of 70% in the full Li‐Se cell, delivers a large reversible capacity of 625 mAh gSe‐1 as opposed to 505.8 mAh gSe‐1 achieved for the pristine Se cell. This clearly shows the advantage of the carbon in improving the capacity of the Li‐Se cell. To further circumvent the issues of polyselenide dissolution and shuttle which cause severe capacity fade, a tungsten oxide interlayer is drop‐cast over the battery separator. While the oxide layer conducts Li‐ions which is evidenced from a Li‐ion diffusion coefficient of 4.2 × 10‐9 cm2 s‐1, it simultaneously blocks the polyselenide cross‐over for it is impermeable to polyselenides, thereby reducing the capacity fade with cycling. The outcome of this unique approach is reflected in the reversible capacities of 808 and 510 mAh gSe‐1, achieved for the Li‐oxide@separator/Se‐ alkali activated carbon cell before and after 100 cycles, thus demonstrating that carbon and oxide can efficiently restrict the capacity fade and improve the performances of Li‐Se cells.

A simple strategy to improve the efficiency of a ZnO-nanorod-based dye-sensitized solar cell (DSSC) by use of Au-encapsulated carbon dots (Au@C-dots) in the photoanode is presented. The localized surface plasmonic resonance of Au in the 500-550 nm range coupled with the ability of C-dots to undergo charge separation increase the energy-harvesting efficiency of the DSSC with ZnO/N719/Au@C-dots photoanodes. Charge transfer from N719 dye to Au@C-dots is confirmed by fluorescence and lifetime enhancements of Au@C-dots. Forster resonance energy transfer (FRET) from the gap states of ZnO nanorods to N719 dye is also ratified and the energy transfer rate is 4.4×108 s-1 and the Forster radius is 1.89 nm. The overall power conversion efficiency of the plasmonic and FRET-enabled DSSC with ZnO/N719/Au@C-dots as the photoanode, I2/I- as the electrolyte and multiwalled carbon nanotubes as the counter electrode is 4.1 %, greater by 29 % compared to a traditional ZnO/N719 cell. Covering all possibilities: Au@C-dots function as plasmonic electron conduits and also undergo photo-induced charge separation in FRET-enabled high-performance ZnO based dye-sensitized solar cells

We are able to grow high quality InN films on indium metal induced 1 × 1 and 7 × 7 superstructural phases of Si(111) at lower growth temperatures than those previously employed. With multi-technique characterization probes, we show the promising route to obtain better crystallinity and emission properties for films that are grown on the 1 × 1 surface reconstruction at 200 °C, as compared to those grown on 7 × 7 reconstruction. These effects are observed in a narrow growth parametric region, and attributed to the better integral match of the 2D unit cells with the substrate reconstruction. Further improvement in the quality of InN films is accomplished by growing InN on the above formed epitaxial layers as intermediate layers which display PL emission even at room temperature. The effect of structural quality, carrier concentration, and stoichiometry on band edge emission and electron mobility of these films, show us directions towards obtaining improved quality InN films.

The alterations in physical property across different space groups of the same material are sometimes conveniently reflected by the crystal structure as a function of temperature. However, mirroring the physical property and crystal parameters over a wide range of temperatures within the same space group is quite unusual. Remarkably, Rietveld analyses of the X-ray diffraction patterns of PrMn0.9O3 (ABO3) nanoparticles (NPs) with a constant Pnma space group from 300 to 10 K could successfully predict the four magnetic phases, viz. paramagnetic, antiferromagnetic (AFM), ferromagnetic (FM), and spin-glass-like ordering. The increase in Mn-O-Mn bond angles and tolerance factor leads to FM ordering below ∼100 K in usually AFM PrMn0.9O3 NPs. The concurrent decrease of lattice cell volume and Mn-O-Mn bond angles near the AFM to FM transition temperature (Tc) suggests that the AFM character increases just above Tc due to atomic deformations and reduced Mn-Mn separation. The predictions from crystal structure refinement were successfully verified from the cooling path of the temperature-dependent field-cooled magnetization measurements. A mechanism involving incoherent spin reversal due to competition between the neighboring spins undergoing antiparallel to parallel spin rotations was suggested. The structure-property parallelism was cross-checked with the A-site vacant Pr0.9MnO3.2 NPs.

Gadolinium nanoparticles, deposited via an inert gas evaporation method, show improved stability towards oxidation and it is therefore possible to carry out an ex-situ investigation on "bare" Gd nanoparticles, i.e., in the absence of a protective Pd layer, for the first time. A size-induced structural transformation from hexagonal close packing to the higher-symmetry face-centered cubic structure is observed. The important observation of hydrogen-Gd-nanoparticle interaction at room temperature and atmospheric pressure, without a Pd catalytic layer, makes Gd nanoparticles a potential candidate for hydrogen-sensing, switching, and storage applications.

We demonstrate here that nanostructuring of GaN thin film significantly enhances the band-edge emission, due to structural and geometrical effects. Films of increasing roughness are formed by kinetic control in a PA-MBE system and their morphological, structural and optical properties are compared by complementary characterization probes. The nanowall configuration with largest pore size (≈215 nm) shows a two orders of magnitude enhancement of integrated PL intensity in comparison to a GaN epilayer. Finite difference time domain (FDTD) simulation is performed to explain the role of total internal reflection and scattering on light extraction. The extended defects terminate proximal to interface, leading to most regions of the nanowalls are defect free, enhancing light generation. The observation of broad HRXRD rocking curves is attributed to a mosaicity that originates due to mutual misorientation of the nanowalls. Thus, the low dislocation density in the nanowalls and their suitable geometry promotes high light emission and extraction, respectively, offering this nanostructure as a potential material for high brightness LED fabrication.