Although there have been several studies on the powder form, there has yet to be a report on the bulk crystal growth and its property studies of LiNiO 2 . In the present study, we report the first successful growth of a LiNiO 2 single crystal by employing the optical floating-zone technique. Structural properties have been studied using single-crystal X-ray diffraction (XRD). The structural refinement of the single-crystal XRD data, along with the Laue diffraction patterns, confirms that this system crystallizes in a rhombohedral unit cell in space group R 3 m and the presence of a single grain along the length of the grown crystal. Furthermore, for the first time, we have observed and determined their superstructures as a function of temperature using single-crystal XRD. We have also conducted a study using the high flux of synchrotron X-rays to demonstrate the mechanism which drives the superstructure witnessed by the single-crystal XRD. Resonant elastic X-ray scattering was used to confirm the superstructure and the mixed valence state of different Ni sites. No additional ordering phenomena were observed, including magnetic or electronic ordering. Our study demonstrates the optimization of LiNiO 2 growth parameters and provides information about atomic and electronic ordering in the system, including the onset of a superstructure phase. This will provide a basis for further work in developing improved cathode materials and understanding quantum spin liquids.

AbstractAlthough the LiCoO2 (LCO) cathode material has been widely used in commercial lithium ion batteries (LIB) and shows high stability, LIB’s improvements have several challenges that still need to be overcome. In this paper, we have studied the in-operando structural properties of LCO within battery cells using Bragg Coherent X-ray Diffraction Imaging to identify ways to optimise the LCO batteries’ cycling. We have successfully reconstructed the X-ray scattering phase variation (a fingerprint of atomic displacement) within a ≈ (1.6 × 1.4 × 1.3) μm3 LCO nanocrystal across a charge/discharge cycle. Reconstructions indicate strained domains forming, expanding, and fragmenting near the surface of the nanocrystal during charging, with a determined maximum relative lattice displacements of 0.467 Å. While discharging, all domains replicate in reverse the effects observed from the charging states, but with a lower maximum relative lattice displacements of 0.226 Å. These findings show the inefficiency-increasing domain dynamics within LCO lattices during cycling.

We have developed conductive, lightweight, and porous composite of polyvinylidene difluoride by blending with synthesized conjugated terpolymer and graphene for conductive polymer composite applications. The new conjugated terpolymer designated as PEPy-TP is synthesized from 3,4-ethylenedioxythiophene, 1-pyrenecarboxzaldehyde, and heptaldehyde through friedel craft reaction. The synthesized terpolymer PEPy-TP have been blended with polyvinylidene difluoride and graphene nanosheets to form porous composite and has been characterized using XRD, TGA, TG-DSC, DTA, DTG, SEM, EDX, and Dielectric spectroscopy. The porous composite is comprised of varying weight percentages of (1, 3, and 5%) of GNS and 10 wt% PEPy-TP in PVDF. The thermal studies on the porous composites indicated that the decomposition occurred at a temperature around 270 and 470 degrees C corresponds to the PEPy-TP and PVDF/PEPy-TP/GNS (1, 3, and 5%), respectively. The EDX spectrum of neat PEPy-TP polymer and their porous composites of PVDF/PEPy-TP/GNS (1, 3, and 5%) result clearly shows the presence of all elements, such as C, O, S, and F with an atomic weight percentage also. The PVDF/PEPy-TP/5% GNS porous composites having a tremendous electrical conductivity and the dielectric constant value is 56 at 1 MHz and their conductivity of this polymer porous composites value is determined to be 4.9 x 10(-6) S/cm at 100 kHz, respectively.

Chromium (Cr3+) doped iron pyrite (FeS2) thin films were deposited on ITO substrate by a facile electrochemical deposition process. The effect of chromium content on structural, optical, electrical, morphological, and electrocatalytic behavior of the pyrite thin films were examined. X - ray diffraction studies confirmed the formation of cubic crystal structure of deposited thin films. Atomic force microscopy results indicate that Cr3+ doping has strong influence on crystallinity, surface roughness and grain size of as-deposited thin films. Further, bandgap reduction was found in Cr3+ doped FeS2 thin films. The interfacial charge resistance of fabricated thin films was investigated by electrochemical impedance spectroscopy and 3 mole % Cr3+ doped FeS2 thin films showed excellent conductivity with a low charge transfer resistance of 49 Ω. Further, the electrocatalytic performance of the prepared pyrite thin films was investigated. Cr doped thin films were found to exhibit better performance. Anti-structural modeling was opted to investigate the characteristics of defects in fabricated thin films and it was established that Cr3+substitutionmay form cation (Fe2+) vacancies which could be responsible for enhanced photochemical and electrochemical activities in Cr-doped FeS2 thin films.

Organic NLO materials, 2-methoxy-N,N-diphenylbenzamide (2MNNDPB), 4-Methoxy-N,N-diphenylbenzamide (4MNNDPB) and 3-methoxy-N,N-diphenylbenzamide (3MNNDPB), were synthesized by benzoylation of N,N-diphenylamine with methoxy substituted benzoyl chlorides. The single crystals of 2MNNDPB (3a), 3MNNDPB (3b) and 4MNNDPB (3c) were grown by a slow evaporation method in a dimethyl sulfoxide solvent. The X-ray diffraction shows that 2MNNDPB, 3MNNDPB and 4MNNDPB crystals belong to triclinic, orthorhombic and monoclinic crystallographic systems with space groups Pbca, P-1 and P21/n, respectively. FTIR spectra revealed the various functional groups and the chemical bonding, with the amide carbonyl peak appearing at 1658, 1649 and 1656 cm−1 in 2MNNDPB, 3MNNDPB and 4MNNDPB, respectively, and also confirmed by NMR spectra (1H and 13C) the number of protons and carbons present in the synthesized materials. UV–Vis spectra show 67

The present review presents important research work carried out relating to potential applications of nanostructures loaded conductive polymer composite materials, particularly the nanocomposites of polypyrrole, polyaniline, polythiophene, Chitosan and Cellulose based polymers. Wide literature data is abstracted in this review pertaining to synthesis of nanocomposites, target analysts, sensitivity of the reported electrode material and the contribution of conducting polymer to achieve high efficiency. A significant attention has been given to the conductive polymer composites in the detection of pathogenic microorganism and their DNA, particularly through electrochemical methods.

High performance batteries based on the movement of Li ions in Li x CoO2 have made possible a revolution in mobile electronic technology, from laptops to mobile phones. However, the scarcity of Li and the demand for energy storage for renewables has led to intense interest in Na-ion batteries, including structurally-related Na x CoO2. Here we have determined the diffusion mechanism for Na0.8CoO2 using diffuse x-ray scattering, quasi-elastic neutron scattering and ab-initio molecular dynamics simulations, and we find that the sodium ordering provides diffusion pathways and governs the diffusion rate. Above T ~ 290 K the so-called partially disordered stripe superstructure provides channels for quasi-1D diffusion, and melting of the sodium ordering leads to 2D superionic diffusion above T ~ 370 K. We obtain quantitative agreement between our microscopic study of the hopping mechanism and bulk self-diffusion measurements. Our approach can be applied widely to other Na- or Li-ion battery materials.

The first successful growth of neutron-size single-crystal LixCoO2 by the optical floating-zone technique is reported. Structural properties have been studied using the time-of-flight neutron Laue diffraction technique. Our experiment is the first report of the LixCoO2 single-crystal neutron study. The neutron diffraction profile yields sharp, strong Bragg reflections, indicating a single grain of high crystalline quality. The structural refinement from the single-crystal neutron diffraction data indicated a trigonal structure of space group R3¯m, and a Li concentration x=0.87. No superlattice reflections were detected. The surface morphology analysed by scanning electron microscopy revealed the absence of cracks. The magnetic susceptibility was measured in a field of 1 T with Hc and H⊥c, and an antiferromagnetic transition was observed at ~10 K, with no magnetic impurities.

We have grown single crystals of NaxCayCoO2 and determined their superstructures as a function of composition using neutron and x-ray diffraction. Inclusion of Ca 2+ stabilises a single superstructure across a wide range of temperatures and concentrations. The superstructure in the Na + layers is based on arrays of divacancy clusters with Ca 2+ ions occupying the central site, and it has an ideal concentration Na 4/7 Ca 1/7 CoO2. Previous measurements of the thermoelectric properties on this system are discussed in light of this superstructure. Na 4/7 Ca 1/7 CoO2 corresponds to the maximum in thermoelectric performance of this system.

Thin films of La0.9Ca0.1MnO3 with thicknesses in the range of 40-200 nm grown on (100) SrTiO3 employing pulsed laser deposition (PLD) technique have been investigated by measuring structure and transport properties. The structural properties of the films were studied by X-ray diffraction (XRD) technique employing 2ï

Sodium cobaltate has latterly received attention due to its appealing thermoelectric properties. By combining inelastic X-ray and neutron scattering results with detailed first-principles calculations, it is now shown that low-energy rattling modes of sodium ions within multi-vacancy clusters play a central role in determining the low thermal conductivity of this material.

An in-situ sulphated-combustion synthesis is reported to obtain gadolinium [Ce0.9Gd0.1O1.95] and samarium [Ce0.9Sm0.1O1.95] doped ceria electrolytes for solid oxide fuel cells (SOFCs). Nitrate precursors of cerium, gadolinium and samarium reactants were mixed homogenously with a citric acid fuel with an in-situ addition of 10 and 20 mol% ammonium sulphate [(NH4)2SO4]. The mixture was combusted at 500 o C and subsequently calcined at 700 o C. The influence of the sulphate addition on the morphology of ceria particles has been analyzed. It is seen that the in-situ SO4 2- ions highly favors the nucleation and growth of doped ceria electrolytes on a nanometer scale with an added advantage of improved crystallinity. TEM analysis indicates loosely agglomerated and nearly spherically shaped ceria nano particles with a maximum particle size of 20 nm.

In the present communication, a novel composite nanofibrous electrode is developed for the detection of superoxide anion (O(2)˙(-)) in phosphate buffered saline (PBS). The composite fiber electrode is fabricated by dispersing gold nanoparticles onto poly(methyl methacrylate) (PMMA)-polyaniline (PANI) core-shell electrospun nanofibers. The constructed architecture is proven to be a favorable environment for the immobilization of the enzyme, superoxide dismutase (SOD). Direct electron transfer is achieved between SOD and the electrode with an electron transfer rate constant of 8.93 s(-1). At an applied potential of +300 mV, PMMA/PANI-Au(nano)/SOD-ESCFM shows highly sensitive detection of O(2)˙(-). In addition to this, quantification of different activities of SOD is realized at PMMA/PANI-Au(nano)/SOD-ESCFM. These analytical features offer great potential for construction of the third-generation O(2)˙(-) biosensor.

Efforts have been made in optimizing growth conditions for bulk textured growth of RuSr 2 GdCu 2 O 8 (Ru-1212) employing top seeded growth technique (TSG). Thermal stability and peritectic temperature ( T p ) have been determined by TG–DTA analysis. The study facilitates appropriate thermal treatments to yield good quality sample. The structural study of the as grown sample has been carried out by X-ray diffraction technique. Morphological study by polarized optical microscope (PLOM) and scanning electron microscope (SEM) reveals the growth mechanism. Subsequently, the stoichiometry has been confirmed by energy dispersive X-ray analysis (EDAX). The observed characterization results show the influence of superconducting property on growth technique and allow one to correlate between the physical properties and experimental technique.

A new methodology for the fabrication of bienzymatic amperometric glucose biosensor based on the use of an organic–inorganic hybrid is presented. The fabrication involves a self-assembly directed one-pot electrochemical process. Bi-enzymes, horseradish peroxidase (HRP) and glucose oxidase (GOx) are immobilized into the porous and electroactive silica–polyaniline hybrid composite through electrochemical polymerization of N[3-(trimethoxysilyl)propyl]aniline in the presence of enzymes. The modified electrode is designated as PTMSPA/HRP-GOx. The direct electron transfer of HRP is achieved at the modified electrode. Also, the electrode exhibits excellent bio-electro-catalytic activity for the reduction of hydrogen peroxide. The response current at PTMSPA/HRP-GOx modified electrode revealed a good linear relationship with concentration of glucose range between 1 and 20mM with a response time of 7s. Thus, the modified electrode shows the combined advantages of polyaniline and silica networks through synergistic influence from the individual components. The PTMSPA assembly has shown the potential for a third generation amperometric biosensor.

Nanostructured, hollow spheres of polydiphenylamine (HS-PDPA) are prepared through a “soft template assisted self-assembly” approach. An enzymatic glucose biosensor is fabricated through immobilizing glucose oxidase (GOx) into HS-PDPA matrix. The HS-PDPA–GOx electrode exhibits a pair of well-defined reversible redox peaks with a fast heterogeneous electron transfer rate. At an applied potential of +0.65V, HS-PDPA–GOx electrode possesses high sensitivity (1.77μAmM−1cm−2), stability and reproducibility towards glucose. The amperometric current response of HS-PDPA–GOx to glucose is linear in the concentration range between 1 and 28mM with a detection limit of 0.05mM (S/N=3). Also, HS-PDPA–GOx electrode shows high selectivity towards glucose in the presence of ascorbic acid, uric acid and acetaminophen at their maximum physiological concentrations.

The present work focuses on the sintering of the Nd1.85Ce0.15CuO4 phase in the form of sputtering targets. The method of manufacture, based on a careful control of the microstructure, is of fundamental importance in ensuring the reliability of Nd1.85Ce0.15CuO4 targets and the subsequent realization of high-quality sputter-deposited thin films. In this study the Nd1.85Ce0.15CuO4 targets were prepared by a standard solid state reaction technique. We investigated the influence of the thermal treatment on the phase formation by employing X-ray diffraction (XRD) technique, scanning electron microscopy (SEM) and energy dispersion spectrometry (EDS) analyses. As the growth temperature increases beyond the eutectic point, the achievement of a liquid phase yields a homogeneous grain growth. The results presented here are expected to be of particular usefulness in tailoring the growth of high quality thin films.

A new methodology involving the combination of a soft template (surfactant) and an ionic liquid (co-surfactant) is used to electrodeposit poly(3,4-ethylenedioxythiophene) (PEDOT) nanofibers. Electrochemical deposition of palladium nanoparticles and glucose oxidase (GOx) immobilization are done sequentially into nanofibrous PEDOT to fabricate the modified electrode (ME) (denoted as PEDOT-Pd/GOx-ME). The PEDOT-Pd/GOx-ME displays excellent performances for glucose at +0.4 V (vs. Ag/AgCl) with a high sensitivity (1.6 mA M(-)(1) cm(-2)) in a wider linear concentration range, 0.5 to 30 mM (correlation coefficient of 0.9985). Further, the electrode is insusceptible to the electroactive interfering species.

Thin films of La0.9Ca0.1MnO3 (LCMO) with various thicknesses in the range of 40–200nm were deposited on (100) SrTiO3 (STO) substrates using the pulsed laser deposition technique. The as-grown LCMO films were characterized with respect to the structure as well as their magnetic and transport properties. The X-ray diffraction results show that high quality, single phase and ‘b’ axis orientated epitaxial LCMO thin films have been produced successfully. Out-of-plane lattice parameters has been found to increase with the film thickness. Transport measurements, performed using standard four probe technique, and SQUID magnetometry revealed a ferromagnetic-insulating phase consistent with the bulk phase diagram.