Investigation of nuclear quantum effect on the hydrogen bonds of ammonium dihydrogen phosphate using single-crystal neutron diffraction and theoretical modelling

The heterostructure of patterned CdS / CdTe thin films with back contact have been devised with electron beam lithography and fabricated using sputter deposition technique. The metallic contacts for n-CdS and p-CdTe are patterned such that both are placed at the bottom of the cell. This avoids losses due to contact shading and increases absorption in the window layer. Patterning of the device surface helps in increasing the junction area which can modulate the absorption of more number of photons due to total internal reflection. Computing the surface area between a planar and a patterned device has revealed 133% increase in the junction area. The physical and optical properties of the sputter-deposited CdS / CdTe layers are also presented. J–V characteristics of the solar cell showed the fill factor to be 25.9%, open circuit voltage to be 17 mV and short-circuit current density to be \(113.68~\hbox {A}/\hbox {m}^{2}\). The increase in surface area is directly related to the increase in the short circuit current of the photovoltaic cell, which is observed from the results of simulated model in Atlas / Silvaco.     

Tamarind seed skin-derived fiber-like carbon nanostructures as novel anode material for lithium-ion battery

Demand of low-cost carbonaceous anode materials for lithium-ion batteries has led to the development of anode materials from different bio-sources. In this regard, tamarind seed (skin) was used as a precursor to prepare disordered carbon as an anode material for lithium-ion batteries. The carbon was prepared through simple hydrothermal method and was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) measurements, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. It exhibited amorphous carbon particles arranged in a fiber-like morphology with high surface area of 508 m² g^?1. The binder content was optimized for the carbon to achieve high and stable capacity. Electrochemical performance of the as-prepared carbon with optimized binder content showed a stable reversible specific capacity of 224 mAhg^?1 after 300 cycles at 1 C-rate. The stable cycling performance of carbon at high current rate is explained by electrochemical impedance spectroscopy (EIS) and FE-SEM data of cycled electrodes. The low cost and stable specific capacity make the carbon as potential anode material for lithium-ion battery.

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Graphical abstract Fiber-like carbon nanostructures from tamarind seed (skin) (TDC) via simple and effective hydrothermal method and its application as a novel anode material for lithium-ion battery.

     

Free and forced finite amplitude oscillation of a spherical shell of radially isotropic elastic material

A spherical elastic shell with radial transverse isotropy is considered. The periods of finite amplitude radial oscillation of the shell have been obtained in two cases, namely (i) when both the surfaces of the shell are free from traction, and (ii) when the shell boundaries are uniformly loaded in such a way that the pressure difference between inner and outer surfaces is constant with respect to time. It is observed that for free oscillation to take place it is necessary to impose a new restriction on the strain energy function in addition to those already obtained for finite amplitude oscillation of an isotropic elastic shell. In the forced oscillation case however the required conditions are of the same form as in the corresponding case for isotropic media.     

Low-temperature polymer-assisted synthesis of shape-tunable zinc oxide nanostructures dispersible in both aqueous and non-aqueous media

We report the shape-controlled synthesis of zinc oxide (ZnO) nanostructures by a poly(vinyl methyl ether) (PVME)-assisted alkaline hydrolysis of zinc acetate at low temperature (20 °C). In this method, ZnO nanostructures of various morphologies including dumbbells, lances and triangles have been successfully prepared via a simple variation of different reaction parameters such as polymer concentration, pH of the reaction mixture and precursor concentration. However, without PVME, ZnO of such structurally uniform morphologies were not formed; rather ZnO of a mixture of defined and undefined morphologies were obtained indicating PVME-assisted the growth of such regular shaped ZnO nanostructures. HRTEM analysis of lance- and triangle-shaped samples as well as SAED patterns of all kinds of samples (dumbbell, lance and triangle) revealed that the ZnO nanostrcutures are single crystalline in nature and might form through oriented growth. XRD analysis also revealed the formation of well crystalline ZnO with a hexagonal structure. FTIR spectroscopy and TGA analysis confirmed the adsorption of PVME on the surface of ZnO nanostructures. Being a solvent adaptable polymer, the adsorbed PVME makes these shaped ZnO nanostructures highly dispersible in both polar and non-polar organic solvents including water. The extent of dispersibility in different solvents was studied by spectroscopic and microscopic techniques. Such solvent adoptability of PVME-coated ZnO nanostructures increases its ease of applications in device fabrication as well as in biological systems.     

A water-soluble polythiophene-Au nanoparticle composite for pH sensing

In this paper, we report the development of a reversible pH sensor in aqueous medium based on the fluorescence properties of a polythiophene-gold nanoparticle (Au NP) composite. The composite was synthesized in water by simultaneous reduction of HAuCl(4) to Au NPs and polymerization of thiophene in the presence of no additional reagents. It was stable for weeks and had characteristic emissions, which changed in the pH range of 3.0 to 6.0, thus providing a mean for probing the pH of an aqueous solution. Measurement of the pH could be performed over several cycles of titrations, pointing to the robustness of the materials for such sensing applications. The mass spectra of the composite at two extreme pH values were identical, indicating that the primary structure of the polymer was not affected due to changes in pH of the medium. Transmission electron microscopic (TEM) measurements indicated the presence of small sized Au NPs with the polymer in the milieu. The composite could be titrated by acid (or base) and considering the acid-base equilibria at different pHs, we have been able to calculate the pK(eq) of the composite, which was further used in calculating the pH of an aqueous solution from the emission spectrum of the composite. Our approach took advantage of redox chemistry in synthesizing the water-soluble composite and the optical behavior of a conjugated polymer in developing an important pH sensor, which may form the basis of further development of versatile pH or other sensors by suitably modifying the backbone of the monomer.     

Polymer-mediated chain-like self-assembly of functionalized gold nanoparticles

We report an easy solution phase template-based method to assemble mercaptoundecanoic acid-functionalized gold nanoparticles (MUA-GNPs) along poly(ethylene oxide) (PEO) chains. Transmission electron microscopy (TEM) images show one-dimensional and two-dimensional chain-like sequences of GNPs resembling PEO chains. The progress of the assembly was monitored by the evaluation of surface plasmon resonance band of MUA-GNPs with time by UV-vis spectroscopy. The assembly process is a result of hydrogen bonding interaction between the ethereal oxygen of PEO and carboxylic acid group of MUA attached to GNPs surface, which was confirmed through FTIR spectroscopy. The interaction between PEO and MUA-GNPs was further confirmed by thermal analysis using differential scanning calorimetry.     

Deviation problems in ray optics in the light of the refined unambiguous definitions of angles of incidence,reflection and refraction

This paper makes use of the newly introduced refined unambiguous definitions of angle of incidence, angle of reflection and angle of refraction to give birth to novel vectorial treatment for the calculation of deviation of a ray of light in each of a few cases of ray optics. The problem of calculation of minimum deviation of a ray of light in passing through a prism has also been considered in the light of the refined unambiguous definitions of angle of incidence and angle of refraction. The use of vectorial treatment increases the range of applicability of vector algebra. Furthermore, incorporation of the refined unambiguous definitions of the aforesaid three angles in the novel treatment offered is much clearer leaving no room for confusion and it will enhance and sophisticate the optical field.     

Thermal tunability in terahertz metamaterials fabricated on strontium titanate single-crystal substrates

We report an experimental demonstration of thermal tuning of resonance frequency in a planar terahertz metamaterial consisting of a gold split-ring resonator array fabricated on a bulk single-crystal strontium titanate (SrTiO?) substrate. Cooling the metamaterial starting from 409 K down to 150 K causes about a 43% shift in resonance frequency, and there is very little variation in resonance strength. The resonance shift is due to the temperature-dependent dielectric constant of the strontium titanate. The experiment opens up avenues for designing tunable terahertz devices by exploiting the temperature-sensitive characteristic of high dielectric constant substrates and complex metal oxide materials.