Advanced Materials Research Vol. 665

Abstract: Nanocrystalline Fe-doped TiO₂ was prepared by Sol-Gel technique, which was followed by freeze at-30°C temperature for 12hrs. The obtained Gel was thermally treated at 200,400,600 and 800°C. X-ray Powder Diffraction (XRD), Scanning Electron microscopy (SEM), UV-Vis Spectroscopy, Photo luminescence (PL) and EDAX was used to study its Structural and Optical properties. All Fe-doped TiO₂ nanostructures show an appearance of Red shift relative to the bulk TiO₂. The XRD pattern show the coexistence of major anatase phase and minor brookite phase for samples treated up to 600°C. Whereas at 800°C rutile is the only phase observed. All Fe doped TiO₂ nanostructures show an appearance of Red shift relative to bulk undoped TiO₂. The magnetic property by Gouy Balance of Fe doped TiO₂ exhibit Peramagnetism at room temperature.

Abstract: Gadolinium (Gd) is a weak magnetic element at room temperature. Gadolinium oxide (Gd₂O₃) is a poor semiconductor with para-magnetism. In this work Gadolinium oxide is prepared from the thermal dissociation of Gadolinium acetate. The average cluster size is found to be dependent on the number of the sintering time. In this present work an attempt has been made to characterize the developed Gadolinium oxide. Experimental probes used to characterize it are optical absorbance (UV-VIS); Fourier transformed infra red (FTIR) spectroscopy, DC current voltage characteristics (CVC) and photo-sensitivity studies of the developed specimens. Gadolinium oxide exhibits a good optical sensing property.

Abstract: Electronic transport property like electrical resistivity (ρ) of Co-Cr liquid binary alloy is calculated using Faber-Ziman formulation. To describe electron-ion interaction we have used newly constructed parametric free model potential along with Ashcroft-Langreth (AL) partial structure factor. To see the effect of exchange and correlation effect on electrical resistivity, we have used different local field correction functions like Hartree, Taylor and Sarkar et al. From present results, it is seen that good agreements between present results and experimental data have been achieved. Lastly we conclude that our model potential successfully produces the data of electrical resistivity (ρ) of Co-Cr liquid binary alloy.

Abstract: Present article deals with atomic transport properties like self-diffusion coefficient (D) and viscosity coefficient (η) of 4d transition metals in liquid state. To describe structural information we have used different reference systems like Percus - Yevick Hard Sphere (PYHS), One Component Plasma (OCP) and Charge Hard Sphere (CHS) systems alongwith our newly constructed parameter free model potential. To see the effect of different correction functions on atomic transport properties, we have used different local field correction functions like Hartree (H), Vashishta-Singwi (VS), Hubbard-Sham (HS), Sarkar et al (S), Ichimaru-Utsumi (IU), Taylor (T) and Farid et al (F). From the present results we conclude that our newly constructed model potential successfully calculated atomic transport properties of 4d transition metals in liquid phase.

Abstract: The thermodynamic properties like heat of mixing (ΔE), entropy of mixing (ΔS) and volume of mixing (ΔΩ) of Fe-Co liquid binary alloys are computed using our newly constructed parameter free model potential. We have also attempted to investigate the effect of various forms of exchange and correlation functions, namely, Hartree (H) and Taylor (T) on the thermodynamic properties of Fe-Co liquid binary alloys. It is found that the proper choice of the model potential along with the local field correction function play an important role in investigating the thermodynamic properties of Fe-Co liquid binary alloys.

Abstract: In the present investigation, we report theoretical study of total energy, energy band gap in X-direction, bulk modulus, elastic constants and pressure derivative of elastic constants of Si_1-xSn_xsolid solution using higher-order perturbation theory along with application of our proposed potential, where x is concentration of Sn. The parameter of our potential is determined using zero-pressure equilibrium condition. In the present calculations, The local-field correction function can be employed to consider exchange and correlation effects. The present study showed that the physical quantities under investigation varied with the concentration of the constituent element.

Abstract: Apart from its promising new material for technological innovations and applications, graphene offers a new and novel physics. In recent past, both single layer and bilayer Graphene have extensively been studied. Properties of Graphene sharply differ from that of 2DEG observed in doped semiconductor heterostructures. One of the important properties requisite for device making is charge transport. It has been suggested that considering a scattering mechanism based on screened charged impurities, one can obtain from a Boltzmann equation approach a conductivity that agrees with the experimental result on graphene. In this paper, we present a calculation of electron-impurity scattering rate, as a function of quasi particle energy ε measured from Fermi energy εf, in doped bilayer graphene for both high temperature TTf and low temperature TTf regimes. In the low temperature limit, we observe dip at normalized energy y=1.0, which is absent in the high temperature limit. Our numerical calculation shows that scattering rate remains almost constant with temperature in both regimes.

Abstract: In this paper structural and optical properties of CdSe thin films with different thickness deposited by thermal evaporation under vacuum onto glass substrates are presented. The structural investigations performed by means of XRD technique showed that the films have a polycrystalline and hexagonal (würtzite) structure. The values of some important parameters of the studied films (absorption coefficient and optical bandgap energy) are determined from transmission spectra. The values of the optical bandgap energy (E_g) calculated from the absorption spectra, ranged between 1.67 - 1.74 eV.

Abstract: A simple formula for effective dielectric constant of composite material or DMD is proposed. In case of magnetic element in the composite the effect of magnetic susceptibility is taken into account to describe the dielectric behavior. A theoretical formulation of the proposed dielectric function along with an experimental result is presented here. The overall results are found to be good and consistent .

Abstract: Pure and various amino acids (L-histidine, L-threonine, DL-methionine) doped KDP crystals were grown by slow solvent evaporation technique. The doping of amino acids was confirmed by C, H, N analysis, FTIR spectroscopy and paper chromatography .Pure and doped KDP crystals were subjected to Vickers microhardness studies. Indentations were made on smooth (100) as grown faces of pure and doped crystals. The Vickers indenter loads were varied from 0.298 N to 0.981 N in order to study the effect of load on microhardness. A number of indents were made at each load and the mean diagonal length (d) was used in calculating the Vickers Hardness Number (H_V). The Vickers micro-hardness decreased as amino acid doping level was increased indicating that the KDP crystals became softer after doping. The Indentation size effect (ISE) the Kicks law as well as PSR model was verified for all samples. The values of the load independent hardness and the Newtonian pressure (W) were higher in pure KDP crystals than the amino acids doped KDP crystals. It was found that as the doping concentration of amino acids increased the values of load independent hardness and Newtonian pressure decreased. Hays and Kendall law analysis was also applied to the hardness data.