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Infrared reflectivity of pure and doped CuGeO3  [PDF]
A. Damascelli,D. van der Marel,F. Parmigiani,G. Dhalenne,A. Revcolevschi
Physics , 1997, DOI: 10.1016/S0921-4526(97)00472-9
Abstract: We investigated the far- and mid-infrared reflectivity (20-6000 wavenumber) of several pure and doped CuGeO3 single crystals. The b-axis and c-axis optical response is presented for different temperatures between 4 K and 300 K. Moreover, a full group theoretical analysis of the lattice vibrational modes of CuGeO3 in the high temperature undistorted phase as well as in the low temperature spin-Peierls phase is reported and compared to the experimental results. We observe the activation of zone boundary phonons along the b axis of the crystal below the spin-Peierls transition temperature.
Structural, Optical, Electrical and Thermal Characterizations of Pure and L-alanine Doped Ammonium Dihydrogen Phosphate Crystals  [PDF]
Ferdousi Akhtar, Jiban Podder
Journal of Crystallization Process and Technology (JCPT) , 2011, DOI: 10.4236/jcpt.2011.12004
Abstract: Pure ammonium diyidrogen phosphate and L-alanine doped ammonium diyidrogen phosphate crystals were grown from aqueous solutions by natural evaporation process. The grown crystals are characterized by Fourier Transform Infrared spectroscopy, Energy Dispersive X-ray, UV-visible spectroscopy and differential thermal analysis. Crystal structure has been studied by powder X-ray diffraction. Pure and doped crystals both possessed tetragonal structure. The optical transparency is found to increase with the increase of doping concentration in the grown crystals and band gap energies of all crystals have been calculated at their cut off frequencies. It is found that the optical band gap increases with doping concentrations. D.C.electrical conductivity of grown crystals along the growth axis was carried out at temperatures ranging from 35-140°C by the conventional two-probe method. The conductivity of the crystals increases with temperature and also increases with the L-alanine concentration. The decomposition temperatures and weight loss have been estimated from the Thermo Gravimetric Analysis and Differential Thermal Analysis and hardness was found from the Vicker’s microhardness measurement.
DFT study of optical properties of pure and doped Graphene  [PDF]
Pooja Rani,Girija S Dubey,V. K. Jindal
Physics , 2014,
Abstract: Ab-initio calculations based on density functional theory (DFT) have been performed to study the optical properties of pure graphene and have been compared to that of individual boron (B), nitrogen (N) and BN co-doped graphene sheet. The effect of doping has been investigated by varying the concentrations of dopants from 3.125 % (one atom of the dopant in 32 host atoms) to 6.25 % (six dopant atoms in 50 host atoms) for individual B and N doping and from 37.5 % (one B/N pair in 32 host atoms) to 18.75 % for BN co-doping. Positions of the dopants have also been varied for the same concentration of substitution doping. The dielectric matrix has been calculated within the random phase approximation (RPA) using VASP (Vienna ab-initio Simulation Package) code. The dielectric function, absorption spectrum and energy loss-function of single layer graphene sheet have been calculated for light polarization parallel and perpendicular to the plane of graphene sheet and compared with doping graphene. The calculated dielectric functions and energy-loss spectra are in reasonable agreement with the available theoretical and experimental results for pure graphene. It has been found that individual B and N doping does not significantly affect the imaginary dielectric function and hence the absorption spectra. However, significant red shift in absorption towards visible range of the radiation at high doping is found to occur for the B/N co-doping. The results can be used to tailor the optical properties of graphene in visible region.
Electrical and optical studies of pure and Ni-doped CdS quantum dots
Arfat Firdous,D. Singh,M. M. Ahmad
Applied Nanoscience , 2013, DOI: 10.1007/s13204-012-0065-0
Abstract: Quantum dots of CdS and Ni-doped CdS were synthesized through chemical precipitation method using a high-boiling solvent. Nanocrystallinity of the as prepared nanostructure is confirmed using X-ray diffraction (XRD). The mean crystal size obtained by full-width half maxima (FWHM) analysis is 3.33 nm for CdS, 3.37 nm for CdS:Ni (2 mM) and 3.39 nm for CdS:Ni (4 mM). The electrical conductivity data reveal semiconducting behaviour of both pure CdS and Ni-doped CdS nano-crystals. The optical absorption analysis conducted in UV–vis range 200–900 nm reveals the transparency of these nanocrystals in entire visible range but not in ultraviolet range. The results based on optical analysis yield band gap values as 2.65 eV for CdS, 2.59 eV for CdS:Ni (2 mM) and 2.53 eV for CdS:Ni (4 mM) nanoparticles. This implies that pure CdS and Ni doped CdS are blue shifted with respect to the bulk CdS (2.42 eV); however, Nickel doped CdS nanocrystals are red shifted with respect to pure CdS nanocrystals.
Optical Studies of a Pure and Dye Doped Nematic Liquid Crystal E-24
V. S. CHANDEL,S. MANOHAR,J. P. SHUKLA,R. MANOHAR
Transactions on Electrical and Electronic Materials , 2012,
Abstract: The present paper reports the comparative optical behavior of a pure nematic mixture E-24 and its anthraquinonedye doped sample. The variation in the ordinary and extraordinary refractive index (no, ne) of the pure and dye dopedsamples with temperature has been discussed and it has been found that doped sample have a less refractive indexcompared to the pure sample. The variation in the order parameter for pure and doped samples with temperature hasbeen discussed and it has been seen that the doped sample has a higher order parameter; the possible reasons havebeen discussed. The variations in birefringence and optical transmittance have also been presented here.
Magneto-Optical Spectroscopy of Anatase TiO2 Doped with Co  [PDF]
T. Fukumura,Y. Yamada,K. Tamura,K. Nakajima,T. Aoyama,A. Tsukazaki,M. Sumiya,S. Fuke,Y. Segawa,T. Chikyow,T. Hasegawa,H. Koinuma,M. Kawasaki
Physics , 2002,
Abstract: Magneto-optical spectroscopy of a transparent ferromagnetic semiconductor, anatase TiO2 doped with Co, is carried out at room temperature. A large magneto-optical response with ferromagnetic field dependence is observed throughout from ultraviolet to visible range and increases with increasing Co content or carrier concentration. The magnitude of magnetic circular dichroism (MCD) per unit thickness has a peak around the absorption edge such a huge value of ~10400 degree/cm at 3.57 eV for a 10 mol% Co-doped specimen. Although the results are not sufficient to prove that the ferromagnetism is in the ordinary framework of diluted magnetic semiconductors, the coexistence of Co impurity and mobile carrier is shown to transform the band structure of host TiO2 to generate ferromagnetism.
A Study on Structural, Optical, Electrical and Etching Characteristics of Pure and L-Alanine Doped Potassium Dihydrogen Phosphate Crystals  [PDF]
Ferdousi Akhtar, Jiban Podder
Journal of Crystallization Process and Technology (JCPT) , 2011, DOI: 10.4236/jcpt.2011.13009
Abstract: Pure potassium dihydrogen phosphate (KDP) crystals and KDP doped with L-alanine have been grown by slow evaporation technique at room temperature. Grown crystals have been characterized using powder X-ray diffraction, (XRD), Energy Dispersive X-ray spectroscopy (EDX) and Fourier Transform Infrared spectroscopy (FTIR). The presence of L-alanine into pure KDP crystal was confirmed by FTIR and EDX spectra. Crystal structure has been studied by XRD. Pure KDP and L-alanine doped KDP crystals both possessed tetragonal structure. The transparency is found to increase with the increase of doping concentrations of the grown crystals as observed by UV-Vis spectra. A.C. electrical conductivity of grown crystals along the growth axis was carried out at various temperatures ranging from 35?C - 400?C. Dielectric constant and dielectric losses are measured as a function of temperature and this study reveals the contribution of space charge polarization. Crystal defects and surface morphology are studied by dissolution solvent technique and reveals the step growth mechanism for both pure and doped crystals.
The Loss of Optical Fiber with Pure Quartz Core and Fluorine—Doped Glass Cladding  [PDF]
Yaming Gao, Guang Feng, Yongjian Liu, Shuwen Zhou, Shouzheng Zhu
Optics and Photonics Journal (OPJ) , 2013, DOI: 10.4236/opj.2013.31019
Abstract:

The optical fiber with pure quartz core and Fluorine-doped glass cladding was made by POD (plasma outside deposition) technique in some corporations, while we used the creative technique of “overcladding F-doped tube onto quartz rod in high temperature” to make the optical fiber which has the same structure as that from POD, in order to research and compare the influence factors on the loss of the fiber, our research work includes contrast experiments on coating polymers with different refractive index and the concentricity error of the fiber core and cladding. The measurement results show us that there are great differences in the loss spectra between the different fiber samples. We made analysis of it.

Growth, Optical and Dielectric Studies on Pure and L-Lysine Doped KDP Crystals  [PDF]
N. Kanagathara,G. Anbalagan
International Journal of Optics , 2012, DOI: 10.1155/2012/826763
Abstract: Optically good quality single crystals of pure and L-lysine monohydrochloride-doped KDP crystals have been grown by a slow evaporation method. The grown crystals have been subjected to optical and dielectric studies. The UV-Vis spectrum shows the transmitting ability of the crystals in the entire visible region and transmittance percentage is increased for the doped KDP crystals. From the dielectric study, it is found that the dielectric constant and the dielectric loss of L-lysine-doped KDP crystals were lower than the pure KDP crystals. Hence L-lysine-doped KDP crystals are found to be more beneficial from an application point of view as compared to pure KDP crystals. 1. Introduction Materials with large optical nonlinearity are needed to realize applications in optoelectronics, telecommunication industries, laser technology, and optical storage devices. ADP and KDP are two of the oldest crystals grown in large size for many applications and continue to be interesting materials both academically and industrially. Potassium dihydrogen phosphate (KDP) is an excellent inorganic nonlinear optical (NLO) material and has a considerable interest amongst several research workers because of its wide frequency, high efficiency of frequency conversion, and high damage threshold against high power laser. With the aim of improving the SHG efficiency of KDP, researchers have attempted to modify KDP crystals either by doping different type of impurities or by changing the growth conditions [1–9]. Most of amino acids possess NLO property; therefore, it is of interest to dope them in KDP crystals. The effects of amino acid on the NLO efficiency of KDP crystals were already published [1–3]. L-Lysine monohydrochloride dihydrate is a potential material to produce semiorganic crystals for nonlinear optical applications [3]. Also L-Lysine monohydrochloride dihydrate can be used as novel elasto-eletro-optical materials [4, 5]. In the present study, L-Lysine monohydrochloride amino-acid-doped KDP crystals were grown by slow aqueous solvent evaporation technique. The optical and dielectric behavior of the both pure and lysine-doped KDP crystals has been studied and discussed in detail. 2. Experimental Procedure Commercially available KDP was used for the growth. Without any further purification, KDP was dissolved in double distilled water. After obtaining the saturation, the solution was stirred well for just two hours, filtered and kept separately for the slow evaporation. Similar procedure followed for the addition of 0.2% of L-Lysine monohydrochloride to the saturated
Structural, Optical, and Electrochromic Properties of Pure and Mo-Doped WO3 Films by RF Magnetron Sputtering  [PDF]
Vempuluri Madhavi,Paruchuri Kondaiah,Obili Mahammad Hussain,Suda Uthanna
Conference Papers in Science , 2013, DOI: 10.1155/2013/104047
Abstract: Pure and Mo-doped WO3 films were formed on ITO-coated glass substrate held at 473?K by RF magnetron sputtering technique. The structural, morphological, and optical properties of pure and Mo-doped WO3 thin films have been systematically studied. The structural properties revealed that the pure WO3 films exhibited a (020) reflection related to the orthorhombic phase of WO3, whereas Mo-doped films showed (200) reflection. The surface morphology revealed that pure WO3 films showed the dense surface and Mo-doped films contained agglomerated grains which were uniformly distributed on the surface of the substrate. The optical transmittance decreased from 85% to 75% for pure and Mo-doped WO3 films, respectively. The electrochromic properties of the films were measured by cyclic voltametry in 1?M Li2SO4 electrolyte solution. The optical modulation of pure WO3 films at near IR was 50%, and the calculated color efficiency was 33.8?cm2/C, while in Mo-doped WO3 the efficiency improved to 42.5?cm2/C. 1. Introduction Tungsten oxide (WO3) is the most widely used electrochromic material because of easiness in synthesis and favorable electrical and optical properties. The application of electrochromic materials for smart windows, displays, and antiglare mirrors and several applications have been developed such as control of incoming daylight into buildings, smart windows, rearview mirrors, and aphotochromic and electrochromic devices [1–3]. Tungsten oxide is the extensively studied electrochromic material [4, 5]. Doping of vanadium, niobium, nitrogen, titanium, or nickel to WO3 enhances in the electrochromic properties. Muthu Karuppasamy and Subramanyam [6] reported that the color efficiency decreased from 121 to 13?cm2/C with increase of vanadium doping of 9 at. % in tungsten oxide films deposited by DC magnetron sputtering. Bathe and Patil [7] studied the electrochromic properties of niobium-doped WO3 films, and the coloration efficiency decreased with the increase of niobium doping. Sun et al. [8] studied the nitrogen-doped WO3 films formed by reactive DC pulsed sputtering and the color efficiency achieved to 45?cm2/C at 5 at. % nitrogen doped films. Karuppasamy and Subrahmanyam [9] studied the electrochromic properties of titanium doped tungsten oxide films and realized the improvement in the electrochromic properties with the increase of titanium doping. Gesheva et al. [10] studied MoO3-WO3 films formed by chemical vapour deposition method and showed the color efficiency of 141?cm2/C when compared to 84?cm2/C for WO3 and 39?cm2/C for MoO3 films. Valyukh et al. [11]
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