Materials Science

In this study, the optimized geometries, electronic structures, polarizability, hyper polarizability and dipole moment of the chosen (E)-3-(5-(anthracen-3-yl)-hexahydrothieno[3,4-b][1,4]dioxin-7-yl)-2-cyanoacrylic acid (E-3-2- CYANOACRYLIC ACID) dye sensitizer has been analyzed by using Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) calculations (based on hybrid functional B3LYP). The HOMO and LUMO energies of the dye (E-3-2- CYANOACRYLIC ACID) are -4.84 and -2.22 eV respectively based on DFT calculations. To understand the conversion efficiency of the chosen dye architecture unit we selected TiO2 as a model for semiconductor. Results reveal that the selected dye sensitizer exhibits large dipole moment difference between the ground and excited state which is comparable to that of metal based dye sensitizers. Results concluded that intramolecular energy transfer is occurring in (E-3-2- CYANOACRYLIC ACID) and further the large dipole moment would be expected to give high photo-current conversion efficiency in practical Dye sensitizer solar cells (DSSC) besides promising candidate as a sensitizer for DSSC applications.

The formal-logical analysis of the Boltzmann distribution on the basis of probability theory and Gibbs quantum canonical distribution is proposed. It is shown that the Boltzmann distribution function is neither a reliable result of probability theory nor a consequence of Gibbs quantum canonical distribution. Conclusion is that the Boltzmann distribution function has no statistical and physical meaning, and the concept “Boltzmann distribution” should be abolished.

The tri-nitrophenol p-hydroxyacetophenone (TNPHAP) single crystal was grown from aqueous solution by Sankaranarayanan-Ramasamy (SR) unidirectional growth method. The grown crystal with cylindrical shape about 12 mm diameter and 55 mm length was obtained by S-R technique. The formation of TNPHAP was confirmed by single crystal and powder X-ray diffraction studies. The optical properties of grown crystal has been analyzed by UV-Vis absorption studies. The mechanical strength of the grown crystal has been studied using Vicker’s microhardness tester. The dielectric constant and dielectric loss was studied as the function of frequencies. The results are discussed in detail.

Good quality of semi organic single crystals of a urea copper sulphate (UCS) was grown from solution by slow evaporation technique at room temperature. Good optical quality single crystals with dimensions 15×11×3 mm3 were obtained. The grown crystal had been confirmed by single X-Ray Diffraction Method. UV -Vis absorption, studies reveals that the grown crystal was optically transparent through the visible range. The vibrational frequencies of various functional groups in the crystals had been derived from Fourier transform infrared spectrum. Dielectric studies have been made. Dielectric studies give information about the charge transport mechanism of a material. The optical absorption studies indicate that for the sample, optical transparency window is quite wide, making it suitable for NLO applications.

Density functional theory (DFT) was used to determine the ground state geometries of Luminol and new design dyes (L1-Dye-1 L1-Dye-2, L1-Dye-3 and L1-Dye-4). The time dependant density functional theory (TDDFT) was used to calculate the excitation energies. All the calculations were performed in both gas and solvent phase. Theoretical analyses of the Luminol dye molecule and its derivatives with Chlorine (Cl), Sulfur(S), Selenium (Se) substituent were performed. Calculations were performed based on the framework of density functional theory (DFT) with the Becke3-parameter-Lee-Yang-Parr(B3LYP) functional, where the 6-311+G(d,p) basis set was employed. All this for study they properties for be used with metal oxides in dye-sensitized solar cells (DSSC). Each of the molecules was theoretically analyzed.

Promising future applications of ferrite nanoparticles in medicine, making many devices like permanent magnets, memory storage devices etc. Ferrite nanoparticles have been the emerging focus of the recent scientific research. In the present investigation Cadmium Titanium Cobalt ferrites (CdTiCoFe2O4) is synthesized by Sol-Gel method. This approach is simple, faster, eco-friendly, cost effective and suitable for large scale production. These synthesized ferrites are characterized by X-ray diffraction (XRD), FTIR, UV–VIS spectroscopic techniques and Scanning Electron Microscopy (SEM). The crystalline nature and the structure of the synthesized nanoferrites are confirmed from X-Ray diffraction analysis. The ferrite powders showed XRD line broadening peaks and the average particle size of the materials is calculated as 8.7027 nm using Scherer formula. The strain (?) and dislocation density (?) of the materials are also calculated from XRD data. The optical band energy (Eg) at the edge of absorption band has been determined by the Tauc relation using UV-VIS spectroscopic data. The magnetic properties are studied using Vibrating Sample Magnetometer at room temperature and it is found that this study shows a ferromagnetic behavior of the synthesized ferrites. This significant property allows this type of ferrites can be used in fabrication of magnetic and energy storage media.

This work studies the experimental approach employed in performance investigation of thermoelectric materials using Orthorhombic Tin Sulphide (SnS) crystals as a case study. The sample material was joined with Lead Telluride (PbTe) to form a closed couple in the module. The two junctions of the couples where held at different sets of temperature causing varying sets of temperature gradients with 30°C/m difference between each set. The result obtained reveals that SnS and PbTe module has a high thermoelectric conversion efficiency which ranges from 1.92% to 4.84% for the range of temperature gradient of 60°C/m to 180°C/m. These ranges of thermoelectric conversion efficiency are better than those of commercial thermoelectric modules which has efficiencies of between 0.5% to 1%. It is also seen that SnS module can operate as both low and high temperature thermoelectric material.

This paper presents the preparation and characterization of a series of (PEO+PVP) composites with different ratios of NaF salt. New Na+ ion conducting polymer blend electrolyte films based on semicrystalline polymer poly (ethylene oxide) PEO and poly (vinyl pyrrolidone) PVP complexed with NaF salt were prepared using the solution-cast technique. The features of the complexation and structure of the electrolytes were studied by X- ray diffraction (XRD) and FTIR techniques. Frequency dependent conductivity were obtained from complex impedence (cole-cole) plots. It was observed that the magnitude of conductivity increased with increasing temperature and followed Arrhenius behavior throughout with three regions having different activation energies. The activation energy values were found to decrease with increasing concentration of NaF.

Lead graphite-pencils have been associated in our daily life but it could be an easy source for understanding many unexplained properties of graphite based materials. The present work shows that lead pencils belong not only to the class of heterogeneous materials but also exhibited good soft ferromagnetic properties at room temperature. The structural, morphological, optical and electrical properties such as X-ray diffraction (XRD), scanning electron microscopy (SEM), optical absorption, photoluminescence (PL) were studied. Ohmic nature of the material was confirmed by electric conductivity studies.

With the aim of contributing to the knowledge of South-India Medieval age brick production, the mineralogy of briquettes excavated from the site of Gangaikondacholapuram (India) has been studied in order to make inferences concerning the clay preparation and firing techniques of that period. In this work, the fired brick finds (GKSB-1 to GKSB-5) were analysed by three distinct techniques namely Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and SEM/EDS to determine their mineralogical, chemical compositions and microstructures respectively. The relative similarity of compositions, the fine, dense and homogeneous microstructures and the presence of high-temperature phases such as pyroxenes, mullite, analcime and wusite in the sample coded GKSB-1, GKSB-3 and GKSB-5 showed the use of high firing temperatures, in the range 900–1000°C. While the presence of kaolinite and halloysite clay minerals in the briquettes GKSB-2 and GKSB-4 suggests the low temperature of firing (? 600°C) and may be related to adobe bricks, all indicate the adoption of non-calcareous clay with specialized brick making techniques by the brick makers of Gangaikondacholapuram in the 11thto 12th millennia CE. Key words: FT-IR, XRD, SEM/EDS, Firing techniques, ancient brick samples.