Photovoltaic properties of sintered CdS/CdTe solar cells doped with Cu

International Nuclear Information System (INIS)

Park, J.W.; Ahn, B.T.; Im, H.B.; Kim, C.S.

1992-01-01

In this paper, all polycrystalline CdS/CdTe solar cells doped with Cu are prepared by a screen printing and sintering method. Cell parameters of the sintered CdS/CdTe solar cells have been investigated in an attempt to find out the optimum doping conditions and concentrations of Cu by adding various amounts of CuCl 2 either into CdTe layer or into back contact carbon layer. Cell parameters of the sintered CdS/CdTe solar cells which contained various amounts of CuCl 2 in the CdTe layers before sintering stay at about the same values as the amount of CuCl 2 increases up to 25 ppm, and then decreases sharply as the amount of CuCl 2 further increases. The Cu added in the CdTe layer diffuses into the CdS layer during the sintering of the CdS-CdTe composite at 625 degrees C to densify the CdTe layer and causes the decrease in the optical transmission of CdS resulting in the degradation of the cell performance. In case the Cu dopant was dispersed in the back carbon paint and was followed by annealing, all cell parameters are improved significantly compared with those fabricated by adding CuCl 2 in the CdTe layer before sintering. A sintered CdS/CdTe solar cell which contained 25 ppm CuCl 2 in the carbon paste and was annealed at 350 degrees C for 10 min shows the highest efficiency. The efficiency of this cell is 12.4% under solar irradiation with an intensity of 80.4 mW/cm 2

Effect of tellurium doping on the structural, optical, and electrical properties of CdO

Energy Technology Data Exchange (ETDEWEB)

Dakhel, A.A. [Department of Physics, College of Science, University of Bahrain, P.O. Box 32038 (Bahrain)

2010-08-15

Te-doped CdO thin-films (1%, 3%, and 5%) have been prepared by a vacuum evaporation method on glass and silicon-wafer substrates. The prepared films were characterised by X-ray fluorescence, X-ray diffraction, UV-VIS-NIR absorption spectroscopy, and dc-electrical measurements. Experimental data indicate that Te ions doping slightly stresses the host CdO crystalline structure and changes the optical and electrical properties. The bandgap of the host CdO was suddenly narrowed by about 23% due to a little (1%) doping with Te ions. This bandgap shrinkage was explained by effects of trap levels overlapping with conduction band. The electrical behaviours of the Te-doped CdO films show that they are degenerate semiconductors with a bandgap of 1.7-2.2 eV. The 1% Te-doped CdO film shows increase its mobility by about 5 times, conductivity by {proportional_to}140 times, and carrier concentration by {proportional_to}27 times, relative to undoped CdO film. From transparent-conducting-oxide point of view, Te is sufficiently effective for CdO doping. Finally, the absorption in the NIR spectral region was studied in the framework of the classical Drude theory. (author)

Microstructural, optical and electrical properties of Cl-doped CdTe single crystals

Directory of Open Access Journals (Sweden)

Choi Hyojeong

2016-09-01

Full Text Available Microstructural, optical and electrical properties of Cl-doped CdTe crystals grown by the low pressure Bridgman (LPB method were investigated for four different doping concentrations (unintentionally doped, 4.97 × 1019 cm−3, 9.94 × 1019 cm−3 and 1.99 × 1020 cm−3 and three different locations within the ingots (namely, samples from top, middle and bottom positions in the order of the distance from the tip of the ingot. It was shown that Cl dopant suppressed the unwanted secondary (5 1 1 crystalline orientation. Also, the average size and surface coverage of Te inclusions decreased with an increase in Cl doping concentration. Spectroscopic ellipsometry measurements showed that the optical quality of the Cl-doped CdTe single crystals was enhanced. The resistivity of the CdTe sample doped with Cl at the 1.99 × 1020 cm−3 was above 1010 Ω.cm.

Carrier transport dynamics in Mn-doped CdSe quantum dot sensitized solar cells

Science.gov (United States)

Poudyal, Uma; Maloney, Francis S.; Sapkota, Keshab; Wang, Wenyong

2017-10-01

In this work quantum dot sensitized solar cells (QDSSCs) were fabricated with CdSe and Mn-doped CdSe quantum dots (QDs) using the SILAR method. QDSSCs based on Mn-doped CdSe QDs exhibited improved incident photon-to-electron conversion efficiency. Carrier transport dynamics in the QDSSCs were studied using the intensity modulated photocurrent/photovoltage spectroscopy technique, from which transport and recombination time constants could be derived. Compared to CdSe QDSSCs, Mn-CdSe QDSSCs exhibited shorter transport time constant, longer recombination time constant, longer diffusion length, and higher charge collection efficiency. These observations suggested that Mn doping in CdSe QDs could benefit the performance of solar cells based on such nanostructures.

Synthesis, characterization and anti-microbial activity of pure, Cu2+ and Cd2+ doped organic NLO l-arginine trifluoroacetate single crystals

Science.gov (United States)

Prasanyaa, T.; Haris, M.; Jayaramakrishnan, V.; Amgalan, M.; Mathivanan, V.

2013-10-01

Optically transparent Cu2+ and Cd2+ doped l-arginine trifluoroacetate (LATF) single crystals were grown from its aqueous solution using the slow solvent evaporation technique. The grown crystals were characterized by powder x-ray diffraction to confirm the monoclinic crystal structure. The percentage of transmittance measured using the ultraviolet-visible-near infrared spectrophotometer was found to be more than 80% for doped crystals. The functional group analysis of the grown crystals has been made by Fourier transform infrared spectroscopy. Thermogravimetric/differential thermal analysis was performed for the grown crystals. An atomic absorption study was carried out to determine the presence of Cu2+ and Cd2+. The hardness of the grown crystals was assessed and the results show a significant variation in the hardness value between the pure and doped LATF crystals. The second harmonic generation measurements show that Cu2+ doped LATF is 2.8 times greater and Cd2+ doped is 2.6 times greater than KDP. The anti-bacterial and anti-fungal activities of the title compound were performed using the disc diffusion method against standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillus niger and Aspergillus flavus.

Synthesis, characterization and anti-microbial activity of pure, Cu2+ and Cd2+ doped organic NLO l-arginine trifluoroacetate single crystals

International Nuclear Information System (INIS)

Prasanyaa, T; Haris, M; Amgalan, M; Mathivanan, V; Jayaramakrishnan, V

2013-01-01

Optically transparent Cu 2+ and Cd 2+ doped l-arginine trifluoroacetate (LATF) single crystals were grown from its aqueous solution using the slow solvent evaporation technique. The grown crystals were characterized by powder x-ray diffraction to confirm the monoclinic crystal structure. The percentage of transmittance measured using the ultraviolet–visible–near infrared spectrophotometer was found to be more than 80% for doped crystals. The functional group analysis of the grown crystals has been made by Fourier transform infrared spectroscopy. Thermogravimetric/differential thermal analysis was performed for the grown crystals. An atomic absorption study was carried out to determine the presence of Cu 2+ and Cd 2+ . The hardness of the grown crystals was assessed and the results show a significant variation in the hardness value between the pure and doped LATF crystals. The second harmonic generation measurements show that Cu 2+ doped LATF is 2.8 times greater and Cd 2+ doped is 2.6 times greater than KDP. The anti-bacterial and anti-fungal activities of the title compound were performed using the disc diffusion method against standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillus niger and Aspergillus flavus. (paper)

Characteristic analysis on the physical properties of nanostructured Mg-doped CdO thin films—Doping concentration effect

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K. Usharani

2015-06-01

Full Text Available Highly conductive and transparent magnesium-doped cadmium oxide (CdO:Mg thin films have been deposited on suitably cleaned glass substrates maintained at 375 °C by spray pyrolysis technique using perfume atomizer. The magnesium content in the films is varied from 0 to 8 at% in steps of 2 at%. The effect of Mg doping on the structural, morphological, optical and electrical properties of the CdO thin films has been studied. All the films exhibited cubic structure with a preferential orientation along the (1 1 1 plane irrespective of the Mg doping level. SEM analysis showed that the film morphology modifies from spherical shaped grains to closely packed cauliflower shaped nanostructures with Mg doping. Except for the film coated with 2 at% Mg dopant, all the other doped films exhibited a blue shift in the optical band gap. Electrical studies revealed that the CdO:Mg film coated with 8 at% Mg dopant had a minimum resistivity of 0.0853×101 Ω-cm.

Crystal growth and optical properties of CdS-doped lead silicate glass

International Nuclear Information System (INIS)

Liu Hao; Liu Qiming; Zhao Xiujian

2007-01-01

The crystal growth and optical properties of CdS microcrystallite-doped lead silicate glass is investigated in this paper. The existence of CdS nanocrystals was confirmed via X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results reveal that a two-stage heat-treat procedure can produce a better size distribution of CdS nanocrystals than a one-stage heat-treat procedure in glasses. The second harmonic generation (SHG) from the base glass and CdS microcrystallite doped glasses was observed, and the effects of the heat treatments and the thermal poling temperature on the crystallization of CdS and second-order harmonic (SH) intensity were discussed, respectively. It is indicated that samples doped with CdS microcrystallite showed larger SH intensity than that of the base glass. Use of a higher thermal poling temperature than the glass transformation temperature does not result in a good SH intensity in glasses

Sulfonsuccinate (AOT Capped Pure and Mn-Doped CdS Nanoparticles

Directory of Open Access Journals (Sweden)

D. Venkatesan

2012-01-01

Full Text Available CdS nanoparticles and thin films are well known for their excellent semiconducting properties. When transition metal ions are doped into the CdS, it exhibits magnetic properties in addition to semiconducting properties and they are termed as dilute magnetic semiconductors (DMSs. In this paper, we discuss the preparation of sodium bis(2-ethylhexyl sulfonsuccinate (AOT capped CdS nanoparticles and thin films doped with magnetic impurity Mn. Sodium bis(2-ethulexyl sulfonsuccinate (AOT, capping agent promotes the uniform formation of nanoparticles. Optical characterizations are made using the UV-Vis spectrometer, PL, and FTIR. XRD shows the hexagonal structure of the CdS. SEM images and EDS measurements were made for the thin films. EPR shows the clear hyperfine lines corresponding to Mn2+ ion in the CdS nanoparticles.

Pulsed laser induced optical nonlinearities in undoped, copper doped and chromium doped CdS quantum dots

Science.gov (United States)

Sharma, Dimple; Malik, B. P.; Gaur, Arun

2015-04-01

Quantum dots (QDs) of CdS, Cu doped and Cr doped CdS were synthesized through chemical co- precipitation method. The synthesized QDs have been characterized by x-ray diffraction, ultraviolet visible absorption spectroscopy. The diameters of QDs were calculated using Debye-Scherrer’s formula and Brus equation. They are found to be in 3.5-3.8 nm range. The nonlinear properties has been studied by the open and closed aperture Z-scan technique using frequency double Nd:YAG laser. The nonlinear refractive index (n2), nonlinear absorption coefficient (β), third order nonlinear susceptibilities (χ3) of QDs has been calculated. It has been found that the values of nonlinear parameters are higher for doped QDs than undoped CdS QDs. Hence they can be regarded as potential material for the development of optoelectronics and photonics devices.

On the doping problem of CdTe films: The bismuth case

Energy Technology Data Exchange (ETDEWEB)

Vigil-Galan, O. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Brown, M. [Department of Physics and Astronomy, The University of Toledo, 43606 Toledo, OH (United States); Ruiz, C.M. [Depto. Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Vidal-Borbolla, M.A. [Instituto de Investigacion en Comunicacion Optica, Av. Karakorum 1470, Lomas 4a. Secc., 78210 San Luis Potosi, SLP (Mexico); Ramirez-Bon, R. [CINVESTAV-IPN, U. Queretaro, Libramiento Norponiente No. 2000, Fracc. Real de Juriquilla, 76230 Santiago de Queretaro, Qro. (Mexico); Sanchez-Meza, E. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Tufino-Velazquez, M. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico)], E-mail: mtufinovel@yahoo.com.mx; Calixto, M. Estela [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico); Compaan, A.D. [Department of Physics and Astronomy, The University of Toledo, 43606 Toledo, OH (United States); Contreras-Puente, G. [Escuela Superior de Fisica y Matematicas del IPN, Edif. 9, UPALM, 07738 Mexico, D. F. (Mexico)

2008-08-30

The controlled increase of hole concentration is an important issue and still an unsolved problem for polycrystalline CdTe-based solar cells. The typical hole concentration of as-grown CdTe thin-films goes up to 10{sup 13} cm{sup -3}, depending on the specific growth technique. The highest electron concentration obtained for CdS, the suitable window partner material of CdTe, is around 10{sup 15} cm{sup -3}. Thus, the PV-performance of a CdS/CdTe device can be optimized if the hole concentration in CdTe is increased. We have faced up this problem by studying the electrical properties of two types of CdTe films: CdTe films grown by Close Space Vapor Transport using a CdTe:Bi powder as the starting material and CdTe sputtered films doped by implantation with different Bi-doses. Temperature-dependent resistivity and Hall effect measurements and a discussion on the efficiency of both doping processes are presented.

On the doping problem of CdTe films: The bismuth case

International Nuclear Information System (INIS)

Vigil-Galan, O.; Brown, M.; Ruiz, C.M.; Vidal-Borbolla, M.A.; Ramirez-Bon, R.; Sanchez-Meza, E.; Tufino-Velazquez, M.; Calixto, M. Estela; Compaan, A.D.; Contreras-Puente, G.

2008-01-01

The controlled increase of hole concentration is an important issue and still an unsolved problem for polycrystalline CdTe-based solar cells. The typical hole concentration of as-grown CdTe thin-films goes up to 10 13 cm -3 , depending on the specific growth technique. The highest electron concentration obtained for CdS, the suitable window partner material of CdTe, is around 10 15 cm -3 . Thus, the PV-performance of a CdS/CdTe device can be optimized if the hole concentration in CdTe is increased. We have faced up this problem by studying the electrical properties of two types of CdTe films: CdTe films grown by Close Space Vapor Transport using a CdTe:Bi powder as the starting material and CdTe sputtered films doped by implantation with different Bi-doses. Temperature-dependent resistivity and Hall effect measurements and a discussion on the efficiency of both doping processes are presented

Effect of doping concentration on the structural, morphological, optical and electrical properties of Mn-doped CdO thin films

Directory of Open Access Journals (Sweden)

Manjula N.

2015-12-01

Full Text Available Thin films of manganese-doped cadmium oxide (CdO:Mn with different Mn-doping levels (0, 1, 2, 3 and 4 at.% were deposited on glass substrates by employing an inexpensive, simplified spray technique using a perfume atomizer at 375 °C. The influence of Mn incorporation on the structural, morphological, optical and electrical properties of CdO films has been studied. All the films exhibit cubic crystal structure with a (1 1 1 preferential orientation. Mn-doping causes a slight shift of the (1 1 1 diffraction peak towards higher angle. The crystallite size of the films is found to decrease from 34.63 nm to 17.68 nm with an increase in Mn doping concentration. The CdO:Mn film coated with 1 at.% Mn exhibit a high transparency of nearly 90 % which decreases for higher doping concentration. The optical band gap decreases with an increase in Mn doping concentration. All the films have electrical resistivity of the order of 10−4 Ω·cm.

Excimer laser doping technique for application in an integrated CdTe imaging device

CERN Document Server

Mochizuki, D; Aoki, T; Tomita, Y; Nihashi, T; Hatanaka, Y

1999-01-01

CdTe is an attractive semiconductor material for applications in solid-state high-energy X-ray and gamma-ray imaging systems because of its high absorption coefficient, large band gap, good mobility lifetime product of holes and stability at normal atmospheric conditions. We propose a new concept for fabricating an integrated CdTe with monolithic circuit configuration for two-dimensional imaging systems suitable for medical, research or industrial applications and operation at room temperature. A new doping technique has been recently developed that employs excimer laser radiation to diffuse impurity atoms into the semiconductor. Accordingly, heavily doped n- and p-type layers with resistivities less than 1 OMEGA cm can be formed on the high resistive CdTe crystals. We have further extended this technique for doping with spatial pattern. We will present the laser doping technique and various results thus obtained. Spatially patterned doping is demonstrated and we propose the use of these doping techniques for...

Indium doped Cd{sub 1-x}Zn{sub x}O alloys as wide window transparent conductors

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wei [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, The Center for Physical Experiments, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yu, Kin Man, E-mail: kinmanyu@cityu.edu.hk [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics and Materials Science, City University of Hong Kong, Kowloon (Hong Kong); Walukiewicz, W. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2015-12-31

We have synthesized Indium doped Cd{sub 1-x}Zn{sub x}O alloys across the full composition range using magnetron sputtering method. The crystallographic structure of these alloys changes from rocksalt (RS) to wurtzite (WZ) when the Zn content is higher than 30%. The rocksalt phase alloys in the composition range 0 < x < 0.3 can be efficiently n-type doped, shifting the absorption edge to 3.25 eV and reducing resistivity to about 2.0 × 10{sup −4} Ω-cm. We found that In doped CdO (ICO) transmits more solar photons than commercial fluorine doped tin oxide (FTO) with comparable sheet conductivity. The infrared transmittance is further extended to longer than 1500 nm wavelengths by depositing the In doped Cd{sub 1-x}Zn{sub x}O in ~ 1% of O{sub 2}. This material has a potential for applications as a transparent conductor for silicon and multi-junction solar cells. - Highlights: • Indium doped Cd1-xZnxO alloys across the full composition range were synthesized. • Alloys change from rocksalt (RS) to wurtzite (WZ) when x is higher than 30%. • RS-Cd1-xZnxO phase can be doped with In as efficiently as CdO, achieving a low resistivity ~ 2.0 × 10{sup −4} Ω-cm. • Wide transparency window from 380 to 1200 nm • In doped CdO transmits more solar photons than commercial fluorine doped tin oxide.

Electrosynthesis and characterization of Fe doped CdSe thin films from ethylene glycol bath

International Nuclear Information System (INIS)

Pawar, S.M.; Moholkar, A.V.; Rajpure, K.Y.; Bhosale, C.H.

2007-01-01

The CdSe and Fe doped CdSe (Fe:CdSe) thin films have been electrodeposited potentiostatically onto the stainless steel and fluorine doped tin oxide (FTO) glass substrates, from ethylene glycol bath containing (CH 3 COO) 2 .Cd.2H 2 O, SeO 2 , and FeCl 3 at room temperature. The doping concentration of Fe is optimized by using (photo) electrochemical (PEC) characterization technique. The deposition mechanism and Fe incorporation are studied by cyclic voltammetry. The structural, surface morphological and optical properties of the deposited CdSe and Fe:CdSe thin films have been studied by X-ray diffraction, scanning electron microscopy (SEM) and optical absorption techniques respectively. The PEC study shows that Fe:CdSe thin films are more photosensitive than that of undoped CdSe thin films. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. SEM studies reveal that the films with uniformly distributed grains over the entire surface of the substrate. The complete surface morphology has been changed after doping. Optical absorption study shows the presence of direct transition and a considerable decrease in bandgap, E g from 1.95 to 1.65 eV

Anodic Titania Nanotube Arrays Sensitized with Mn- or Co-Doped CdS Nanocrystals

International Nuclear Information System (INIS)

Smith, York R.; Gakhar, Ruchi; Merwin, Augustus; Mohanty, Swomitra K.; Chidambaram, Dev; Misra, Mano

2014-01-01

Highlights: • Mn or Co doped CdS where synthesized and deposited onto TiO 2 nanotubular arrays. • Synthesis and deposition were achieved simultaneously using SILAR method. • Various characterization techniques demonstrate lattice incorporation of dopant. • Photoelectrochemical performance was analyzed using AM 1.5 irradiation. • Dopants increases depletion width of CdS and increase photoelectrochemical responses. - Abstract: The use of doped luminescent nanocrystals or quantum dots have mainly been explored for imaging applications; however, recently they have gained interest in solar energy conversion applications due to long electron lifetimes, tunable band gaps and emission by compositional control. In this study, we have examined the application of Mn or Co doped CdS nanocrystals as a sensitizing layer over titania nanotubular arrays synthesized via electrochemical anodization in photoelectrochemical applications. The doped and undoped CdS nanocrystals were simultaneously synthesized and deposited onto the titania surface by adoption of a successive ion layer adsorption-reaction (SILAR) method. Various characterization methods indicate lattice incorporation of the dopant within CdS. The addition of dopants to CdS was found to improve the photoelectrochemical performance by increasing the depletion width of the CdS nanocrystals and reducing recombination losses of charge carriers

Effect of silver doping on the elastic properties of CdS nanoparticles

Science.gov (United States)

Dey, P. C.; Das, R.

2018-05-01

CdS and Ag doped CdS (CdS/Ag) nanoparticles have been prepared via chemical method from a Cadmium acetate precursor and Thiourea. The synthesized CdS and CdS/Ag nanoparticles have been characterized by the X-ray Diffraction and High Resolution Transmission Electron Microscope. Here, these nanoparticles have been synthesized at room temperature and all the characterization have also been done at room temperature only. The XRD results reveal that the products are crystalline with cubic zinc blende structure. HRTEM images show that the prepared nanoparticles are nearly spherical in shape. Williamson-Hall method and Size-Strain Plot (SSP) have been used to study the individual contribution of crystalline sizes and lattice strain on the peak broadening of the CdS and CdS/Ag nanoparticles. The different modified model of Williamson-Hall method such as, uniform deformation model, uniform stress deformation model and uniform energy density deformation model and SSP method have been used to calculate the different physical parameter such as lattice strain, stress and energy density for all diffraction peaks of the XRD, corresponding to the CdS and silver doped CdS (CdS/Ag). The obtained results reveal that the average particle size of the prepared CdS and CdS/Ag nanoparticles estimated from the HRTEM images, Williamson-Hall analysis and SSP method are highly correlated with each other. Further, all these result confirms that doping of Ag significantly affects the elastic properties of CdS.

Magnetic properties of vanadium doped CdTe: Ab initio calculations

Energy Technology Data Exchange (ETDEWEB)

Goumrhar, F. [Laboratory of Physics of High Energy, Modeling & Simulations (LPHE-MS), Faculty of Sciences, Mohammed V University of Rabat, Av. Ibn Batouta, B.P. 1014 Rabat (Morocco); Bahmad, L., E-mail: bahmad@fsr.ac.ma [Laboratory of Magnetism and High Energy Physics (LMPHE-URAC12), Faculty of Sciences, Mohammed V University of Rabat, Av. Ibn Batouta, B.P. 1014 Rabat (Morocco); Mounkachi, O. [Material and Nanomaterial Center, MAScIR Fondation, Rabat (Morocco); Benyoussef, A. [Laboratory of Magnetism and High Energy Physics (LMPHE-URAC12), Faculty of Sciences, Mohammed V University of Rabat, Av. Ibn Batouta, B.P. 1014 Rabat (Morocco); Material and Nanomaterial Center, MAScIR Fondation, Rabat (Morocco); Hassan II Academy of Sciences and Technology, Rabat (Morocco)

2017-04-15

In this paper, we are applying the ab initio calculations to study the magnetic properties of vanadium doped CdTe. This study is based on the Korringa–Kohn–Rostoker method (KKR) combined with the coherent potential approximation (CPA), within the local density approximation (LDA). This method is called KKR-CPA-LDA. We have calculated and plotted the density of states (DOS) in the energy diagram for different concentrations of dopants. We have also investigated the magnetic and half-metallic properties of this compound and shown the mechanism of exchange interaction. Moreover, we have estimated the Curie temperature T{sub c} for different concentrations. Finally, we have shown how the crystal field and the exchange splittings vary as a function of the concentrations.

Structural, morphological and optical properties of Na and K dual doped CdS thin film

International Nuclear Information System (INIS)

Mageswari, S.; Dhivya, L.; Palanivel, Balan; Murugan, Ramaswamy

2012-01-01

Highlights: ► Effect of incorporation of Na, K and Na,K dual dopants into CdS thin film was investigated. ► Thin films were prepared by simple chemical bath deposition technique. ► The XRD analysis revealed cubic phase for all the investigated films. ► AFM analysis revealed uniform surface with crack free and densely packed morphology for CdS:Na,K film. ► The band gap value increases for CdS:Na, CdS:K and CdS:Na,K thin films compared to CdS film. - Abstract: CdS, sodium doped CdS (CdS:Na), potassium doped CdS (CdS:K) and sodium and potassium dual doped CdS (CdS:Na,K) thin films were deposited on glass substrate by chemical bath deposition (CBD) technique. Structural, morphological and optical properties of the as-grown films were characterised using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), atomic force microscopy (AFM) and ultraviolet visible (UV–VIS) spectroscopy. The XRD analysis revealed cubic phase for ‘as-deposited’ CdS, CdS:Na, CdS:K and CdS:Na,K dual doped thin films. AFM analysis revealed uniform film surface with crack free and densely packed morphology for CdS:Na,K film. The absorption edge in the optical absorption spectra shifts towards the shorter wavelength for CdS:Na, CdS:K and CdS:Na,K thin films compared to CdS film. The optical band gap of CdS, CdS:Na, CdS:K and CdS:Na,K thin films was found to be 2.31, 2.35, 2.38 and 2.34 eV, respectively.

Mn2+ anchored CdS polymer nanocomposites: An efficient alternative for Mn2+ doped CdS nanoparticles

International Nuclear Information System (INIS)

Saikia, Bhaskar Jyoti; Nath, Bikash Chandra; Borah, Chandramika; Dolui, Swapan Kumar

2015-01-01

A chelating bi-functional polymer brushes was prepared via atom transfer radical polymerization using grafting-from methodology. Mn 2+ -anchored CdS-polymer nanocomposites were synthesized using this graft copolymer by simple chelation method resulting in emission at about 620 nm which originates from the fluorescence of manganese ions embedded on the surface of CdS nanoparticles. This method provides an efficient straightforward substitute of Mn 2+ dopped CdS nanoparticles. Optical properties of the composites were investigated which indicates that simple Mn 2+ chelation and subsequent binding of CdS in a polymer matrix can have similar effect in the luminescence property as those synthesized via complex doping methods. Moreover this methodology can be applied for synthesis of any metal anchored nanocomposites proficiently and cost effectively in large-scale production. - Highlights: • A chelating bifunctional copolymer brush was synthesized via ATRP. • CdS nanoparticles and Mn 2+ were coupled with the bifunctional polymer. • Composites showed emission properties similar to Mn 2+ doped CdS nanoparticles. • Side chain length of the polymers also affect the emission properties of the composites.

Electroluminescent Cu-doped CdS quantum dots

NARCIS (Netherlands)

Stouwdam, J.W.; Janssen, R.A.J.

2009-01-01

Incorporating Cu-doped CdS quantum dots into a polymer host produces efficient light-emitting diodes. The Cu dopant creates a trap level that aligns with the valence band of the host, enabling the direct injection of holes into the quantum dots, which act as emitters. At low current densities, the

Physical properties and characterization of Ag doped CdS thin films

International Nuclear Information System (INIS)

Shah, N.A.; Nazir, A.; Mahmood, W.; Syed, W.A.A.; Butt, S.; Ali, Z.; Maqsood, A.

2012-01-01

Highlights: ► CdS thin films were grown. ► By ion exchange, Ag was doped. ► Physical properties were investigated. - Abstract: Thin films of cadmium sulfide with very well defined preferential orientation and relatively high absorption coefficient were fabricated by thermal evaporation technique. The research is focused to the fabrication and characterization of the compositional data of CdS thin films obtained by using X-ray diffraction, scanning electron microscope along with energy dispersive X-ray spectroscopy. The optical properties were studied by using a UV-VIS-NIR spectrophotometer. The effects of silver-doping by ion exchange process on the properties of as-deposited CdS thin films have been investigated.

Magnetic and dielectric study of Fe-doped CdSe nanoparticles

Science.gov (United States)

Das, Sayantani; Banerjee, Sourish; Bandyopadhyay, Sudipta; Sinha, Tripurari Prasad

2018-01-01

Nanoparticles of cadmium selenide (CdSe) and Fe (5% and 10%) doped CdSe have been synthesized by soft chemical route and found to have cubic structure. The magnetic field dependent magnetization measurement of the doped samples indicates the presence of anti-ferromagnetic order. The temperature dependent magnetization (M-T) measurement under zero field cooled and field cooled conditions has also ruled out the presence of ferromagnetic component in the samples at room temperature as well as low temperature. In order to estimate the anti-ferromagnetic coupling among the doped Fe atoms, an M-T measurement at 500 Oe has been carried out, and the Curie-Weiss temperature θ of the samples has been estimated from the inverse of susceptibility versus temperature plots. The dielectric relaxation peaks are observed in the spectra of imaginary part of dielectric constant. The temperature dependent relaxation time is found to obey the Arrhenius law having activation energy 0.4 eV for Fe doped samples. The frequency dependent conductivity spectra are found to obey the power law. [Figure not available: see fulltext.

Investigation of the structural, optical and electrical transport properties of n-doped CdSe thin films

Science.gov (United States)

Ali, H. M.; Abd El-Ghanny, H. A.

2008-04-01

Thin films of (CdSe)90(In2O3)10, (CdSe)90(SnO2)10 and (CdSe)90(ZnO)10 have been grown on glass substrates by the electron beam evaporation technique. It has been found that undoped and Sn or In doped CdSe films have two direct transitions corresponding to the energy gaps Eg and Eg+Δ due to spin-orbit splitting of the valence band. The electrical resistivity for n-doped CdSe thin films as a function of light exposure time has been studied. The influence of doping on the structural, optical and electrical characteristics of In doped CdSe films has been investigated in detail. The lattice parameters, grain size and dislocation were determined from x-ray diffraction patterns. The optical transmittance and band gap of these films were determined using a double beam spectrophotometer. The DC conductivity of the films was measured in vacuum using a two-probe technique.

N-doping of organic semiconductors by bis-metallosandwich compounds

Science.gov (United States)

Barlow, Stephen; Qi, Yabing; Kahn, Antoine; Marder, Seth; Kim, Sang Bok; Mohapatra, Swagat K.; Guo, Song

2016-01-05

The various inventions disclosed, described, and/or claimed herein relate to the field of methods for n-doping organic semiconductors with certain bis-metallosandwich compounds, the doped compositions produced, and the uses of the doped compositions in organic electronic devices. Metals can be manganese, rhenium, iron, ruthenium, osmium, rhodium, or iridium. Stable and efficient doping can be achieved.

Bromine doping of CdTe and CdMnTe epitaxial layers grown by molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Scholl, S. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Schierstedt, K. von (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Hommel, D. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1993-03-01

We report on the n-type doping of CdTe and CdMnTe with bormine as a novel dopant material. /the thin films were grown by molecular beam epitaxy. ZnBr[sub 2] was used as a source material for the n-type doping. Free carrier concentrations at room temperature of up to 2.8x10[sup 18] cm[sup -3] could be readily obtained for both CdTe as well as CdMnTe thin films with Mn concentrations below 10%. This is to our knowledge the highest value ever obtained for the dilute magnetic semiconductor CdMnTe. For ZnBr[sub 2] source temperatures up to 60 C - corresponding to a free carrier concentration of (2-3)x10[sup 18] cm[sup -3] - the free carrier concentration of the epitaxial film increases with ZnBr[sub 2] source temperature. For higher ZnBr[sub 2] source temperatures compensation becomes dominant, which is indicated by a steep decrease of the free carrier concentration with increasing ZnBr[sub 2] source temperature. In addition the carrier mobility decreases drastically for such high dopant fluxes. A model of bromine incorporation is proposed. (orig.)

Structural and luminescent properties of Fe3+ doped PVA capped CdTe nanoparticles

Directory of Open Access Journals (Sweden)

Ravindranadh K.

2017-07-01

Full Text Available During recent decades, magnetic and semiconductor nanoparticles have attracted significant attention of scientists in various fields of engineering, physics, chemistry, biology and medicine. Fe3+ doped PVA capped CdTe nanoparticles were prepared by co-precipitation method and characterized by powder X-ray diffraction, SEM, TEM, FT-IR, optical, EPR and PL techniques to collect the information about the crystal structure, coordination/local site symmetry of doped Fe3+ ions in the host lattice and the luminescent properties of prepared sample. Powder XRD data revealed that the crystal structure belongs to a cubic system and its lattice cell parameters were evaluated. The average crystallite size was estimated to be 8 nm. The morphology of prepared samples was analyzed by using SEM and TEM investigations. Functional groups of the prepared sample were observed in FT-IR spectra. Optical absorption and EPR studies have shown that on doping, Fe3+ ions enter the host lattice in octahedral site symmetry. PL studies of Fe3+ doped PVA capped CdTe nanoparticles revealed UV and blue emission bands. CIE chromaticity coordinates were also calculated from the emission spectrum of Fe3+ doped PVA capped CdTe nanoparticles.

Effect of Gd{sup 3+} doping and reaction temperature on structural and optical properties of CdS nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Pandey, Gajanan, E-mail: pandeygajanan@rediffmail.com [Department of Applied Chemistry, Babasaheb Bhimrao Ambedkar University, Lucknow, 226025, (U.P.) (India); Dixit, Supriya; Shrivastava, A.K. [School of Studies in Physics, Jiwaji University, Gwalior, 474011, (M.P.) (India)

2015-10-15

Graphical abstract: - Highlights: • Cd{sub 1−x}Gd{sub x}S nanoparticles have been prepared in aqueous medium in presence of CTAB. • From XRD, EDX and ICP-OES study, successful doping of Gd{sup 3+} in CdS has been proved. • Gd{sup 3+} doping reduced size of NCs, while temperature increased size and altered shape. • Gd{sup 3+} doping and reaction temperature influenced the optical properties of NCs. - Abstract: CdS and Gd{sup 3+} ions doped CdS nanoparticles have been prepared at two reaction temperatures 90 and 120 °C in aqueous medium in presence of cationic surfactant cetyltrimethylammonium bromide. X-ray diffraction study revealed predominant formation of zinc blend CdS and Gd:CdS at 90 °C, while at 120 °C, phase pure wurtzite CdS and Gd:CdS were formed. From EDX spectra and ICP-OES analysis, successful doping of Gd{sup 3+} ions in CdS host has been proved. Fourier transform infrared spectroscopy results show the interaction of CTAB through headgroup at the nanoparticles surface. In the transmission electron microscopy images, it has been observed that the reaction temperature and Gd{sup 3+} doping played critical role on size and shape of nanocrystals. In UV–visible absorption as well as photoluminescence emission spectra, size and shape-dependent quantum confinement effect has been observed. On Gd{sup 3+} doping, surface states related emission peak shifted to higher wavelength, while intensity of peaks increased on increasing temperature.

Re-dispersible Li+ and Eu3+ co-doped CdS nanoparticles ...

Indian Academy of Sciences (India)

Also, it can be used as sensor for drug delivery in our body [12,13]. In the present work, we prepare re-dispersible CdS, Li+- and Eu3+-doped CdS nanoparticles in organic solvent by urea hydrolysis at 170◦C and their lumines- cence properties are studied. We propose the mechanism of re-dispersion of CdS nanoparticles ...

Tunable Visible Emission of Ag-Doped CdZnS Alloy Quantum Dots

Directory of Open Access Journals (Sweden)

Sethi Ruchi

2009-01-01

Full Text Available Abstract Highly luminescent Ag-ion-doped Cd1−xZnxS (0 ≤ x ≤ 1 alloy nanocrystals were successfully synthesized by a novel wet chemical precipitation method. Influence of dopant concentration and the Zn/Cd stoichiometric variations in doped alloy nanocrystals have been investigated. The samples were characterized by X-ray diffraction (XRD and high resolution transmission electron microscope (HRTEM to investigate the size and structure of the as prepared nanocrystals. A shift in LO phonon modes from micro-Raman investigations and the elemental analysis from the energy dispersive X-ray analysis (EDAX confirms the stoichiometry of the final product. The average crystallite size was found increasing from 1.0 to 1.4 nm with gradual increase in Ag doping. It was observed that photoluminescence (PL intensity corresponding to Ag impurity (570 nm, relative to the other two bands 480 and 520 nm that originates due to native defects, enhanced and showed slight red shift with increasing silver doping. In addition, decrease in the band gap energy of the doped nanocrystals indicates that the introduction of dopant ion in the host material influence the particle size of the nanocrystals. The composition dependent bandgap engineering in CdZnS:Ag was achieved to attain the deliberate color tunability and demonstrated successfully, which are potentially important for white light generation.

P-nitrophenol degradation using N-doped reduced graphene-CdS nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Gharedaghi, Sepideh [Department of Physics, Islamic Azad University, Tehran (Iran, Islamic Republic of); Kimiagar, Salimeh [Nano Research Lab (NRL), Department of Physics, Islamic Azad University, Tehran (Iran, Islamic Republic of); Safa, Saeed [Young Researchers and Elite Club, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2018-02-15

A series of nitrogen doped reduce graphene-CdS (NRGC) nanocomposites were successfully synthesized by using hydrothermal method. The structure and morphology of the samples were characterized by using FTIR, XRD, SEM, and PL. Photocatalytic activity of the nanocomposites for removing P-nitrophenol (PNP) pollutant was studied under both ultra-violet (UV) and visible light irradiation. The results show that NRGC nanocomposites exhibited higher photocatalytic activity than pure CdS. The degradation rate significantly increased to 50 and 70% by the addition of nitrogen doped reduced graphene oxide (NRGO) to CdS under UV and visible irradiation, respectively. Higher photocatalytic activity of the nanocomposites was due to the role of NRGO as an excellent electron acceptor and transporter. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Enhanced electrochemiluminescence quenching of CdS:Mn nanocrystals by CdTe QDs-doped silica nanoparticles for ultrasensitive detection of thrombin

Science.gov (United States)

Shan, Yun; Xu, Jing-Juan; Chen, Hong-Yuan

2011-07-01

This work reports an aptasensor for ultrasensitive detection of thrombin based on remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from CdS:Mn nanocrystals (NCs) film to CdTe QDs-doped silica nanoparticles (CdTe/SiO2 NPs). CdTe/SiO2 NPs were synthesized via the Stöber method and showed black bodies' strong absorption in a wide spectral range without excitonic emission, which made them excellent ECL quenchers. Within the effective distance of energy scavenging, the ECL quenching efficiency was dependent on the number of CdTe QDs doped into the silica NPs. Using ca. 200 CdTe QDs doped silica NPs on average of 40 nm in diameter as ECL quenching labels, attomolar detection of thrombin was successfully realized. The protein detection involves a competition binding event, based on thrombin replacing CdTe/SiO2 NPs labeled probing DNA which is hybridized with capturing aptamer immobilized on a CdS:Mn NCs film modified glassy carbon electrode surface by specific aptamer-protein affinity interactions. It results in the displacement of ECL quenching labels from CdS:Mn NCs film and concomitant ECL signal recovery. Owing to the high-content CdTe QDs in silica NP, the increment of ECL intensity (ΔIECL) and the concentration of thrombin showed a double logarithmic linear correlation in the range of 5.0 aM~5.0 fM with a detection limit of 1aM. And, the aptasensor hardly responded to antibody, bovine serum albumin (BSA), haemoglobin (Hb) and lysozyme, showing good detection selectivity for thrombin. This long-distance energy scavenging could have a promising application perspective in the detection of biological recognition events on a molecular level.This work reports an aptasensor for ultrasensitive detection of thrombin based on remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from CdS:Mn nanocrystals (NCs) film to CdTe QDs-doped silica nanoparticles (CdTe/SiO2 NPs). CdTe/SiO2 NPs were synthesized via

Effect of thallium doping on the electrical and optical properties of CdO thin films

International Nuclear Information System (INIS)

Dakhel, A.A.

2008-01-01

A series of lightly Tl-doped CdO thin films (1%,1.5%,2%,2.5%, and 3%) have been prepared by a vacuum evaporation method on glass and Si wafer substrates. The prepared films were subjected to structural study by X-ray diffraction, optical characterisation by UV-VIS-NIR absorption spectroscopy, and dc-electrical measurements. Experimental data indicate that Tl 3+ doping slightly stretching stresses the CdO crystalline structure and changes the optical and electrical properties. It was observed that Tl doping widens the energy gap of CdO from 2.22 eV to 2.83 eV via a Burstein-Moss energy level shift. The band gap shrinkage was also observed for carrier concentrations N el >1.13 x 10 20 cm -3 , which was explained by merging of the impurity band with the conduction band. The optical properties were explained by using Hamberg et al.'s band-to-band transitions and classical Drude theory. The electrical behaviour of the samples shows that they are degenerate semiconductors. The 2% Tl-doped CdO sample shows an increase in its mobility by about 1.4 times, conductivity by 5 times, and carrier concentration by 3.6 times relative to the undoped CdO film. From the transparent-conducting-oxide point of view, Tl is sufficiently effective for CdO doping but does not emulate other dopants like In,Sn,Sc, and Y. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Structural, optical and magnetic properties of cobalt-doped CdSe ...

Indian Academy of Sciences (India)

Administrator

Abstract. Pure and Co-doped CdSe nanoparticles have been synthesized by hydrothermal technique. The ... Keywords. Nanoparticles; dilute magnetic semiconductor; ferromagnetism. ... dium dodecyl sulfate (SDS) was used as a surfactant in.

Chemical bath deposition of CdS thin films doped with Zn and Cu

Indian Academy of Sciences (India)

Abstract. Zn- and Cu-doped CdS thin films were deposited onto glass substrates by the chemical bath technique. ... Cadmium sulfide; chemical bath deposition; doping; optical window. 1. ..... at low temperature (10 K), finding similar trends than.

Modulation doping and delta doping of III-V compound semiconductors

NARCIS (Netherlands)

Hendriks, P.; Zwaal, E.A.E.; Haverkort, J.E.M.; Wolter, J.H.; Razeghi, M.

1991-01-01

The transport properties of the 2D electron gas produced by modulation doping of compound semiconductors are reviewed with attention given to the properties at high electric fields. Experimental studies are discussed in which the transport properties lead to insights into current instabilities and

Enhanced electrochemiluminescence quenching of CdS:Mn nanocrystals by CdTe QDs-doped silica nanoparticles for ultrasensitive detection of thrombin.

Science.gov (United States)

Shan, Yun; Xu, Jing-Juan; Chen, Hong-Yuan

2011-07-01

This work reports an aptasensor for ultrasensitive detection of thrombin based on remarkably efficient energy-transfer induced electrochemiluminescence (ECL) quenching from CdS:Mn nanocrystals (NCs) film to CdTe QDs-doped silica nanoparticles (CdTe/SiO(2) NPs). CdTe/SiO(2) NPs were synthesized via the Stöber method and showed black bodies' strong absorption in a wide spectral range without excitonic emission, which made them excellent ECL quenchers. Within the effective distance of energy scavenging, the ECL quenching efficiency was dependent on the number of CdTe QDs doped into the silica NPs. Using ca. 200 CdTe QDs doped silica NPs on average of 40 nm in diameter as ECL quenching labels, attomolar detection of thrombin was successfully realized. The protein detection involves a competition binding event, based on thrombin replacing CdTe/SiO(2) NPs labeled probing DNA which is hybridized with capturing aptamer immobilized on a CdS:Mn NCs film modified glassy carbon electrode surface by specific aptamer-protein affinity interactions. It results in the displacement of ECL quenching labels from CdS:Mn NCs film and concomitant ECL signal recovery. Owing to the high-content CdTe QDs in silica NP, the increment of ECL intensity (ΔI(ECL)) and the concentration of thrombin showed a double logarithmic linear correlation in the range of 5.0 aM∼5.0 fM with a detection limit of 1aM. And, the aptasensor hardly responded to antibody, bovine serum albumin (BSA), haemoglobin (Hb) and lysozyme, showing good detection selectivity for thrombin. This long-distance energy scavenging could have a promising application perspective in the detection of biological recognition events on a molecular level.

EPR and photoluminescence properties of Mn2+ doped CdS nanoparticles synthesized via co-precipitation method.

Science.gov (United States)

Gupta, Atul K; Kripal, Ram

2012-10-01

The structural properties of Mn doped CdS (Mn:CdS) nanoparticles (NPs) are studied using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet-visible (UV-vis), Photoluminescence (PL), Raman and Electron paramagnetic resonance (EPR) spectroscopy. XRD analysis shows the nanostructure with 2-4 nm of average crystallite size. The planes (110), (103) and (112) in XRD pattern distinguish the wurtzite structure of the Mn:CdS NPs. The intensity of the plane (102) increases as the doping concentration of Mn(2+) increases. UV-vis absorption spectra show blue shift as compared to bulk CdS. The optical band gap energy of Mn(2+) (0, 0.35, 0.70 and 1.35 at.%) doped CdS NPs corresponding to absorption edge are found to be 5.29, 5.28, 5.25 and 5.21 eV, respectively. The intensity of luminescence is changing with the concentration of Mn(2+) doped in CdS NPs. Raman spectra show blue shift in fundamental optical phonon mode (1LO) as well as second optical phonon mode (2LO) as compared to bulk CdS. The intensity ratio of the 2LO to 1LO modes slightly decreases as Mn(2+) concentration increases. EPR shows the existence of Mn(2+) with different local structures in CdS nanoparticles. The values of spectroscopic splitting factor (g) and hyperfine interaction constant (A) decrease as Mn(2+) concentration increases in CdS NPs. Copyright © 2012 Elsevier B.V. All rights reserved.

Influence of doping fluorine on the structural, surface morphological and optical properties of CdO films

Energy Technology Data Exchange (ETDEWEB)

Aydogu, S.; Cabuk, G. [Dumlupinar University, Department of Physics, Faculty of Science and Art, Kutahya (Turkey); Coban, M.B. [Balikesir University, Department of Physics, Faculty of Science and Art, Balikesir (Turkey)

2017-06-15

CdO and CdO:F films were prepared by ultrasonic spray pyrolysis method on glass substrates at temperature of 250 ± 5 C. The structural and optical properties of pure and fluorine doped CdO films were characterized by XRD measurements and UV-VIS spectra, respectively. X-ray diffraction patterns show that the films have the polycrystalline structure with preferred orientation along (111) plane. Scherrer Method and Williamson Hall Method were used for calculating of the crystalline grains and strains of films. It is observed that the films at 8% F doped has better crystallinity level, and F doping decreases the defects in CdO films and improves crystallite quality. By UV-VIS spectra, it is revealed that the film with 8% F doped has a high transmittance about 65% in the visible region together with a direct band gap of 2.70 eV. Thicknesses, refractive indices and extinction coefficient values are determined by spectroscopic ellipsometry technique using Cauchy-Urbach model. (orig.)

Implications of orbital hybridization on the electronic properties of doped quantum dots: the case of Cu:CdSe

Science.gov (United States)

Wright, Joshua T.; Forsythe, Kyle; Hutchins, Jamie; Meulenberg, Robert W.

2016-04-01

This paper investigates how chemical dopants affect the electronic properties of CdSe quantum dots (QDs) and why a model that incorporates the concepts of orbital hybridization must be used to understand these properties. Extended X-ray absorption fine structure spectroscopy measurements show that copper dopants in CdSe QDs occur primarily through a statistical doping mechanism. Ultraviolet photoemission spectroscopy (UPS) experiments provide a detailed insight on the valence band (VB) structure of doped and undoped QDs. Using UPS measurements, we are able to observe photoemission from the Cu d-levels above VB maximum of the QDs which allows a complete picture of the energy band landscape of these materials. This information provides insights into many of the physical properties of doped QDs, including the highly debated near-infrared photoluminescence in Cu doped CdSe QDs. We show that all our results point to a common theme of orbital hybridization in Cu doped CdSe QDs which leads to optically and electronically active states below the conduction band minimum. Our model is supported from current-voltage measurements of doped and undoped materials, which exhibit Schottky to Ohmic behavior with Cu doping, suggestive of a tuning of the lowest energy states near the Fermi level.This paper investigates how chemical dopants affect the electronic properties of CdSe quantum dots (QDs) and why a model that incorporates the concepts of orbital hybridization must be used to understand these properties. Extended X-ray absorption fine structure spectroscopy measurements show that copper dopants in CdSe QDs occur primarily through a statistical doping mechanism. Ultraviolet photoemission spectroscopy (UPS) experiments provide a detailed insight on the valence band (VB) structure of doped and undoped QDs. Using UPS measurements, we are able to observe photoemission from the Cu d-levels above VB maximum of the QDs which allows a complete picture of the energy band landscape of

A DFT study of the effects of Sc doping on electronic and optical properties of CdS nanoparticles

Directory of Open Access Journals (Sweden)

Ur Rehman Shafiq

2015-12-01

Full Text Available In the present work a systematic study was carried out to understand the influence of Sc doping on electronic and optical properties of CdS nanoparticles. The geometry optimization and symmetry computation for CdS and Sc doped CdS nanoparticles using Density Functional Theory (DFT on B3LYP level with the QZ4P for Cd and DZ2P for sulphur and Sc were performed by Amsterdam Density Functional (ADF. The results show that HOMO-LUMO gap as well as electronic and optical properties of CdS clusters vary with Sc doping. The HOMO-LUMO gap is affected by the dopant and its value decreases to 0.6 eV. Through considering the numerical integration scheme in the ADF package, we investigated different vibrational modes and our calculated Raman and IR spectra are consistent with the reported result. The calculated IR and Raman peaks of CdS and Sc doped CdS clusters were in the range of 100 to 289 cm−1, 60 cm−1 to 350 cm−1 and 99 cm−1 to 282 cm−1, 60 cm−1 to 350 cm−1, respectively, which was also confirmed by experiment as well as a blue shift occurrence. Subsequently, for deeper research of pure and doped CdS clusters, their absorption spectra were calculated using time-dependent DFT method.

Structural, optical and magnetic properties of Mn diffusion-doped CdS thin films prepared by vacuum evaporation

Energy Technology Data Exchange (ETDEWEB)

Aksu, S. [SoloPower, Inc., 5981 Optical Ct., San Jose, CA 95138 (United States); Bacaksiz, E., E-mail: eminb@ktu.edu.tr [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey); Parlak, M. [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey); Yilmaz, S.; Polat, I.; Altunbas, M. [Department of Physics, Karadeniz Technical University, 61080 Trabzon (Turkey); Tuerksoy, M.; Topkaya, R. [Department of Physics, Gebze Institute of Technology, Gebze, 41400 Kocaeli (Turkey); Ozdogan, K. [Department of Physics, Yildiz Technical University, 34210 Istanbul (Turkey)

2011-10-17

Highlights: {yields} Cadmium sulphide thin films were deposited by vacuum evaporation. {yields} Elemental Mn was deposited onto CdS thin films by using electron beam evaporation and annealed under vacuum at different temperatures. {yields} Structural, optical and magnetic studies of Mn-doped CdS have been investigated. {yields} X-ray diffraction results showed that the undoped CdS film had a zinc-blende structure with a strong preferred orientation along the (1 1 1) direction. {yields} Magnetic measurements show that Mn-doped CdS thin films exhibit a ferromagnetism behavior at room temperature. - Abstract: The effect of Mn-doping on the vacuum deposited CdS thin films has been investigated by studying the changes in the structural, optical and magnetic properties of the films. A thin Mn layer evaporated on the CdS film surface served as the source layer for the diffusion doping. Doping was accomplished by annealing the CdS/Mn stack layers at the temperature range from 300 deg. C to 400 deg. C in step of 50 deg. C for 30 min under vacuum. The X-ray diffraction results showed that the undoped CdS film had a zinc-blende structure with a strong preferred orientation along the (1 1 1) direction. The incorporation of Mn did not cause any change in the texture but reduced the peak intensity and lead to a smaller crystallite size. Investigation of surface morphology using atomic force microscopy confirmed the decrease in the grain size with the Mn diffusion. In addition, a more uniform grain size distribution was observed in the doped films. X-ray photoelectron spectroscopy analysis showed that Mn atoms on the surface of the films were bounded to either sulphur or oxygen atoms. Auger electron spectroscopy of the diffusion-doped CdS sample at 350 deg. C indicated that the atomic Mn concentration was higher close to the surface region and Mn was distributed with a steadily decreasing profile through the bulk of the film with an average atomic concentration value around few

Optical Properties of Al- and Sb-Doped CdTe Thin Films

Directory of Open Access Journals (Sweden)

A. A. J. Al-Douri

2010-01-01

Full Text Available Nondoped and (Al, Sb-doped CdTe thin films with 0.5, 1.5, and 2.5  wt.%, respectively, were deposited by thermal evaporation technique under vacuum onto Corning 7059 glass at substrate temperatures ( of room temperature (RT and 423 K. The optical properties of deposited CdTe films such as band gap, refractive index (n, extinction coefficient (, and dielectric coefficients were investigated as function of Al and Sb wt.% doping, respectively. The results showed that films have direct optical transition. Increasing and the wt.% of both types of dopant, the band gap decrease but the optical is constant as n, and real and imaginary parts of the dielectric coefficient increase.

Shift in optical properties of Mn doped CdS (A DFT+U study)

Science.gov (United States)

khan, M. Junaid Iqbal; Kanwal, Zarfishan; Nauman Usmani, M.

2018-01-01

Current study is based on PBE-GGA and GGA+U computational approach for calculating optical properties of Mn doped CdS. Cd atom in host CdS lattice (rocksalt structure) are substituted with Mn at various lattice positions and shift in optical properties is observed by increasing supercell size by employing PBE-GGA and Hubbard term. Optical properties vary with changing supercell size and show significant change for GGA+U. Blue shift in absorption spectrum and plots for PDOS, TDOS are in accordance with existing reported work. Moreover strong p-d hybridization is observed due to Mn and S orbital interactions and localization of d-states are scrutinized in vicinity of Fermi level or conduction band minima. GGA+U absorption curve shows redshift and a tremendous change in optical properties is observed due to different bonding. Doping Mn into CdS host lattice illustrates enhancement in Opto-electrical properties which maximizes CdS:Mn system scope in optoelectronic devices.

Study of sub band gap absorption of Sn doped CdSe thin films

International Nuclear Information System (INIS)

Kaur, Jagdish; Rani, Mamta; Tripathi, S. K.

2014-01-01

The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively

Study of sub band gap absorption of Sn doped CdSe thin films

Energy Technology Data Exchange (ETDEWEB)

Kaur, Jagdish; Rani, Mamta [Department of Physics, Panjab University, Chandigarh- 160014 (India); Tripathi, S. K., E-mail: surya@pu.ac.in [Centre of Advanced Study in Physics, Panjab University, Chandigarh- 160014 (India)

2014-04-24

The nanocrystalline thin films of Sn doped CdSe at different dopants concentration are prepared by thermal evaporation technique on glass substrate at room temperature. The effect of Sn doping on the optical properties of CdSe has been studied. A decrease in band gap value is observed with increase in Sn concentration. Constant photocurrent method (CPM) is used to study the absorption coefficient in the sub band gap region. Urbach energy has been obtained from CPM spectra which are found to increase with amount of Sn dopants. The refractive index data calculated from transmittance is used for the identification of oscillator strength and oscillator energy using single oscillator model which is found to be 7.7 and 2.12 eV, 6.7 and 2.5 eV for CdSe:Sn 1% and CdSe:Sn 5% respectively.

Self-Assembled Monolayers of CdSe Nanocrystals on Doped GaAs Substrates

DEFF Research Database (Denmark)

Marx, E.; Ginger, D.S.; Walzer, Karsten

2002-01-01

This letter reports the self-assembly and analysis of CdSe nanocrystal monolayers on both p- and a-doped GaAs substrates. The self-assembly was performed using a 1,6-hexanedithiol self-assembled monolayer (SAM) to link CdSe nanocrystals to GaAs substrates. Attenuated total reflection Fourier tran...

Ag-doped CdO nanocatalysts: Preparation, characterization and catechol oxidase activity

Science.gov (United States)

El-Kemary, Maged; El-Mehasseb, Ibrahim; El-Shamy, Hany

2018-06-01

Silver doped cadmium oxide (Ag/CdO) nanoparticles with an average size of 41 nm have been successfully synthesized via thermal decomposition and liquid impregnation technique. The structural characterization has been performed by using several spectroscopic techniques, e.g., X-ray diffraction (XRD), scanning electron microscopy (SEM) and fourier-transform infrared (FT-IR). The catechol oxidase has been studied by UV-visible absorption spectroscopy and fourier-transform infrared as well as the mechanism has been assured by cyclic voltammetry and fluorescence spectroscopy. The results indicate that the oxidation does not occur in the presence of unsupported cadmium oxide particles by silver and in the same time, the catechol oxidase activity of silver doped CdO nanoparticles were improved by about three orders of magnitude than silver ions.

Implications of orbital hybridization on the electronic properties of doped quantum dots: the case of Cu:CdSe

Energy Technology Data Exchange (ETDEWEB)

Wright, Joshua T.; Forsythe, Kyle; Hutchins, Jamie; Meulenberg, Robert W.

2016-04-13

This paper investigates how chemical dopants affect the electronic properties of CdSe quantum dots (QDs) and why a model that incorporates the concepts of orbital hybridization must be used to understand these properties. Extended X-ray absorption fine structure spectroscopy measurements show that copper dopants in CdSe QDs occur primarily through a statistical doping mechanism. Ultraviolet photoemission spectroscopy (UPS) experiments provide a detailed insight on the valence band (VB) structure of doped and undoped QDs. Using UPS measurements, we are able to observe photoemission from the Cu d-levels above VB maximum of the QDs which allows a complete picture of the energy band landscape of these materials. This information provides insights into many of the physical properties of doped QDs, including the highly debated near-infrared photoluminescence in Cu doped CdSe QDs. We show that all our results point to a common theme of orbital hybridization in Cu doped CdSe QDs which leads to optically and electronically active states below the conduction band minimum. Our model is supported from current–voltage measurements of doped and undoped materials, which exhibit Schottky to Ohmic behavior with Cu doping, suggestive of a tuning of the lowest energy states near the Fermi level.

Fabrication and characterization of nanostructured Mg-doped CdS/AAO nanoporous membrane for sensing applications

Science.gov (United States)

Shaban, Mohamed; Mustafa, Mona; Hamdy, Hany

2016-04-01

In this study, Mg-doped CdS nanostructure was deposited onto anodic aluminum oxide (AAO) membrane substrate using sol-gel spin coating method. The AAO membrane was prepared by a two-step anodization process combined with pore widening process. The morphology, chemical composition, and structure of the spin- coated CdS nanostructure have been studied. The morphology of the fabricated AAO membrane and the deposited Mg-doped CdS nanostructure was investigated using scanning electron microscopy (SEM). The SEM of AAO illustrates a typical hexagonal and smooth nanoporous alumina membrane with interpore distance of ~ 100 nm, the pore diameter of ~ 60 nm. SEM of Mgdoped CdS shows porous nanostructured film of CdS nanoparticles. This film well adherents and covers the AAO substrate. The energy dispersive X-ray (EDX) pattern exhibits the signals of Al, O from AAO membrane and Mg, Cd, and S from the deposited CdS. This indicates the high purity of the fabricated membrane and the deposited Mg-doped CdS nanostructure. Using X-ray diffraction (XRD) pattern, Scherrer equation was used to calculate the average crystallite size. Additionally, the texture coefficients and density of dislocations were calculated. The fabricated CdS/AAO was applied to detect glucose of different concentrations. The proposed method has some advantages such as simple technology, low cost of processing, and high throughput. All of these factors facilitate the use of the prepared films in sensing applications.

Effects of ultraviolet light on B-doped CdS thin films prepared by spray pyrolysis method using perfume atomizer

Science.gov (United States)

Novruzov, V. D.; Keskenler, E. F.; Tomakin, M.; Kahraman, S.; Gorur, O.

2013-09-01

Boron doped CdS thin films were deposited by spray pyrolysis method using perfume atomizer. The effects of ultraviolet light on the structural, optical and electrical properties of B-doped CdS thin films were investigated as a function of dopant concentration (B/Cd). X-ray diffraction studies showed that all samples were polycrystalline nature with hexagonal structure. It was determined that the preferred orientation of non-illuminated samples changes from (1 0 1) to (0 0 2) with B concentration. The c lattice constant of films decreases from 6.810 Å to 6.661 Å with boron doping. The XRD peak intensity increased with the illumination for almost all the samples. The lattice parameters of B-doped samples remained nearly constant after illumination. It was found that the optical transmittance, photoluminescence spectra, resistivity and carrier concentration of the B-doped samples are stable after the illumination with UV light. Also the effects of UV light on B-doped CdS/Cu2S solar cell were investigated and it was determined that photoelectrical parameters of B-doped solar cell were more durable against the UV light.

Effects of ultraviolet light on B-doped CdS thin films prepared by spray pyrolysis method using perfume atomizer

Energy Technology Data Exchange (ETDEWEB)

Novruzov, V.D. [Department of Physics, Recep Tayyip Erdogan University, Rize (Turkey); Keskenler, E.F., E-mail: keskenler@gmail.com [Department of Nanotechnology Engineering, Recep Tayyip Erdogan University, Rize (Turkey); Tomakin, M. [Department of Physics, Recep Tayyip Erdogan University, Rize (Turkey); Kahraman, S. [Department of Physics, Mustafa Kemal University, Hatay (Turkey); Gorur, O. [Department of Physics, Abant Izzet Baysal University, Bolu (Turkey)

2013-09-01

Boron doped CdS thin films were deposited by spray pyrolysis method using perfume atomizer. The effects of ultraviolet light on the structural, optical and electrical properties of B-doped CdS thin films were investigated as a function of dopant concentration (B/Cd). X-ray diffraction studies showed that all samples were polycrystalline nature with hexagonal structure. It was determined that the preferred orientation of non-illuminated samples changes from (1 0 1) to (0 0 2) with B concentration. The c lattice constant of films decreases from 6.810 Å to 6.661 Å with boron doping. The XRD peak intensity increased with the illumination for almost all the samples. The lattice parameters of B-doped samples remained nearly constant after illumination. It was found that the optical transmittance, photoluminescence spectra, resistivity and carrier concentration of the B-doped samples are stable after the illumination with UV light. Also the effects of UV light on B-doped CdS/Cu{sub 2}S solar cell were investigated and it was determined that photoelectrical parameters of B-doped solar cell were more durable against the UV light.

Effect of Ag doping on opto-electrical properties of CdS thin films for solar cell applications

International Nuclear Information System (INIS)

Nazir, Adnan; Toma, Andrea; Shah, Nazar Abbas; Panaro, Simone; Butt, Sajid; Sagar, Rizwan ur Rehman; Raja, Waseem; Rasool, Kamran; Maqsood, Asghari

2014-01-01

Highlights: • Polycrystalline CdS thin films are fabricated by means of Close Spaced Sublimation technique. • Ag is doped by simple ion-exchange technique in order to reduce resistivity of CdS thin films. • Remarkable reduction in resistivity without introducing many transparency losses. - Abstract: Cadmium sulfide (CdS) polycrystalline thin films of different thicknesses (ranging from 370 nm to 750 nm) were fabricated on corning glass substrates using Close Spaced Sublimation (CSS) technique. Optical and electrical investigation revealed that CdS thin films show an appreciable transparency (50–70% transmission) in visible range and a highly resistive behavior (10 6 Ω cm). Samples were doped by silver (Ag) at different concentrations, using ion exchange technique, in order to reduce the resistivity of CdS thin films and to improve their efficiency as a window layer for solar cell application. The doping of Ag in pure CdS thin films resulted into an increase of surface roughness and a decrease both in electrical resistivity and in transparency. By optimizing annealing parameters, we were able to properly control the optical properties of the present system. In fact, the Ag doping of pure CdS films has led to a decrease of the sample resistivity by three orders of magnitude (10 3 Ω cm) against a 20% cut in optical transmission

Effect of Low Concentration Sn Doping on Optical Properties of CdS Films Grown by CBD Technique

Directory of Open Access Journals (Sweden)

Mohd Sabri Mohd Ghazali

2011-09-01

Full Text Available Thin and transparent films of doped cadmium sulfide (CdS were obtained on commercial glass substrates by Chemical Bath Deposition (CBD technique. The films were doped with low concentration of Sn, and annealed in air at 300 °C for 45 min. The morphological characterization of the films with different amounts of dopant was made using SEM and EDAX analysis. Optical properties of the films were evaluated by measuring transmittance using the UV-vis spectrophotometer. A comparison of the results revealed that lower concentration of Sn doping improves transmittance of CdS films and makes them suitable for application as window layer of CdTe/CIGS solar cells.

Doping of polycrystalline CdTe for high-efficiency solar cells on flexible metal foil.

Science.gov (United States)

Kranz, Lukas; Gretener, Christina; Perrenoud, Julian; Schmitt, Rafael; Pianezzi, Fabian; La Mattina, Fabio; Blösch, Patrick; Cheah, Erik; Chirilă, Adrian; Fella, Carolin M; Hagendorfer, Harald; Jäger, Timo; Nishiwaki, Shiro; Uhl, Alexander R; Buecheler, Stephan; Tiwari, Ayodhya N

2013-01-01

Roll-to-roll manufacturing of CdTe solar cells on flexible metal foil substrates is one of the most attractive options for low-cost photovoltaic module production. However, various efforts to grow CdTe solar cells on metal foil have resulted in low efficiencies. This is caused by the fact that the conventional device structure must be inverted, which imposes severe restrictions on device processing and consequently limits the electronic quality of the CdTe layer. Here we introduce an innovative concept for the controlled doping of the CdTe layer in the inverted device structure by means of evaporation of sub-monolayer amounts of Cu and subsequent annealing, which enables breakthrough efficiencies up to 13.6%. For the first time, CdTe solar cells on metal foil exceed the 10% efficiency threshold for industrialization. The controlled doping of CdTe with Cu leads to increased hole density, enhanced carrier lifetime and improved carrier collection in the solar cell. Our results offer new research directions for solving persistent challenges of CdTe photovoltaics.

Mn-doped CdS quantum dots sensitized hierarchical TiO2 flower-rod for solar cell application

International Nuclear Information System (INIS)

Yu, Libo; Li, Zhen; Liu, Yingbo; Cheng, Fa; Sun, Shuqing

2014-01-01

A double-layered TiO 2 film which three dimensional (3D) flowers grown on highly ordered self-assembled one dimensional (1D) TiO 2 nanorods was synthesized directly on transparent fluorine-doped tin oxide (FTO) conducting glass substrate by a facile hydrothermal method and was applied as photoanode in Mn-doped CdS quantum dots sensitized solar cells (QDSSCs). The 3D TiO 2 flowers with the increased surface areas can adsorb more QDs, which increased the absorption of light; meanwhile 1D TiO 2 nanorods beneath the flowers offered a direct electrical pathway for photogenerated electrons, accelerating the electron transfer rate. A typical type II band alignment which can effectively separate photogenerated excitons and reduce recombination of electrons and holes was constructed by Mn-doped CdS QDs and TiO 2 flower-rod. The incident photon-to-current conversion efficiency (IPCE) of the Mn-doped CdS/TiO 2 flower-rod solar cell reached to 40% with the polysulfide electrolyte filled in the solar cell. The power conversion efficiency (PCE) of 1.09% was obtained with the Mn-doped CdS/TiO 2 flower-rod solar cell under one sun illumination (AM 1.5G, 100 mW/cm 2 ), which is 105.7% higher than that of the CdS/TiO 2 nanorod solar cell (0.53%).

Coexistence of magnetism and superconductivity in the hole doped FeAs-based superconducting compound

International Nuclear Information System (INIS)

Lu, T.P.; Wu, C.C.; Chou, W.H.; Lan, M.D.

2010-01-01

The magnetic and superconducting properties of the Sm-doped FeAs-based superconducting compound were investigated under wide ranges of temperature and magnetic field. After the systematical magnetic ion substitution, the superconducting transition temperature decreases with increasing magnetic moment. The hysteresis loop of the La 0.87-x Sm x Sr 0.13 FeAsO sample shows a superconducting hysteresis and a paramagnetic background signal. The paramagnetic signal is mainly attributed to the Sm moments. The experiment demonstrates that the coexistence of magnetism and superconductivity in the hole doped FeAs-based superconducting compounds is possible. Unlike the electron doped FeAs-based superconducting compounds SmFeAsOF, the hole doped superconductivity is degraded by the substitution of La by Sm. The hole-doped and electron-doped sides are not symmetric.

Chemical bath deposition of Hg doped CdSe thin films and their characterization

International Nuclear Information System (INIS)

Bhuse, V.M.

2005-01-01

The deliberate addition of Hg in CdSe thin film have been carried out using a simple, modified, chemical bath deposition technique with the objective to study the effect of Hg doping on properties of CdSe thin films. Synthesis was initiated at 278 K temperature using complexed cadmium sulphate, mercuric nitrate and sodium selenosulphate in an aqueous ammonical medium at pH 10. Films were characterized by XRD, SEM, optical absorption, electrical and thermoelectric techniques. The 'as deposited' films were uniform, well adherent, nearly stoichiometric and polycrystalline in a single cubic phase (zinc blende). Crystallite size determined from XRD and SEM was found to increase slightly with addition of Hg. The optical band gap of CdSe remains constant upto 0.05 mol% Hg doping, while it decreases monotonically with further increase in mercury content. Dark dc electrical resistivity and conduction activation energy of CdSe were found to decrease initially upto 0.05 mol% of Hg, thereafter increased for higher values of Hg but remains less than those of CdSe. All the films showed n-type of conductivity. A CdSe film containing 0.05 mol% of Hg showed higher absorption coefficient, and conductivity

Room temperature ferromagnetism in magic-sized Cr-doped CdS diluted magnetic semiconducting quantum dots

International Nuclear Information System (INIS)

Srivastava, Punita; Kumar, Pushpendra; Singh, Kedar

2011-01-01

Manipulation of carrier spins in semiconductors for spintronics applications has received great attention driven by improved functionalities and higher speed operation. Doping of semiconductor nanocrystals by transition-metal ions pronounced as diluted magnetic semiconductors (DMS) has attracted tremendous attention. Such doping is, however, difficult to achieve in low-dimensional strongly quantum-confined nanostructures by conventional growth procedures. In the present case, magic-sized, pure, and Cr-doped CdS DM-QDs have been synthesized by solution phase chemistry (lyothermal method). Structural, optical, and magnetic investigation suggest an intrinsic nature of ferromagnetism with highly quantum-confined system. Optical and magnetic results of pure and doped QDs reveal major physical consequences of dopant localization within the capacity to engineer dopant-carrier exchange interactions introducing magnetic functionalities within the host semiconductor lattice. Unpaired Cr ions in Cd substitutional sites could create spin ordering and ferromagnetic coupling. The results presented herein illustrate some of the remarkable and unexpected complexities that can arise in doped QDs.

TDPAC study of Cd-doped SnO

Energy Technology Data Exchange (ETDEWEB)

Munoz, E. L., E-mail: munoz@fisica.unlp.edu.ar [Universidad Nacional de La Plata, Departamento de Fisica-IFLP (CCT-La Plata, CONICET-UNLP), Facultad de Ciencias Exactas (Argentina); Carbonari, A. W. [Instituto de Pesquisas Energeticas y Nucleares-IPEN-CNEN/SP (Brazil); Errico, L. A. [Universidad Nacional de La Plata, Departamento de Fisica-IFLP (CCT-La Plata, CONICET-UNLP), Facultad de Ciencias Exactas (Argentina); Bibiloni, A. G. [Universidad Nacional de La Plata, Departamento de Fisica, Facultad de Ciencias Exactas (Argentina); Petrilli, H. M. [Universidade de Sao Paulo, Instituto de Fisica (Brazil); Renteria, M. [Universidad Nacional de La Plata, Departamento de Fisica-IFLP (CCT-La Plata, CONICET-UNLP), Facultad de Ciencias Exactas (Argentina)

2007-07-15

The combination of hyperfine techniques and ab initio calculations has been shown to be a powerful tool to unravel structural and electronic characterizations of impurities in solids. A recent example has been the study of Cd-doped SnO, where ab initio calculations questioned previous TDPAC assignments of the electric-field gradient (EFG) in {sup 111}In-implanted Sn-O thin films. Here we present new TDPAC experiments at {sup 111}In-diffused polycrystalline SnO. A reversible temperature dependence of the EFG was observed in the range 295-900 K. The TDPAC results were compared with theoretical calculations performed with the full-potential linearized augmented plane wave (FP-LAPW) method, in the framework of the density functional theory. Through the comparison with the theoretical results, we infer that different electronic surroundings around Cd impurities can coexist in the SnO sample.

TDPAC study of Cd-doped SnO

International Nuclear Information System (INIS)

Munoz, E. L.; Carbonari, A. W.; Errico, L. A.; Bibiloni, A. G.; Petrilli, H. M.; Renteria, M.

2007-01-01

The combination of hyperfine techniques and ab initio calculations has been shown to be a powerful tool to unravel structural and electronic characterizations of impurities in solids. A recent example has been the study of Cd-doped SnO, where ab initio calculations questioned previous TDPAC assignments of the electric-field gradient (EFG) in 111 In-implanted Sn-O thin films. Here we present new TDPAC experiments at 111 In-diffused polycrystalline SnO. A reversible temperature dependence of the EFG was observed in the range 295-900 K. The TDPAC results were compared with theoretical calculations performed with the full-potential linearized augmented plane wave (FP-LAPW) method, in the framework of the density functional theory. Through the comparison with the theoretical results, we infer that different electronic surroundings around Cd impurities can coexist in the SnO sample.

Improving conversion efficiency of CdS quantum dots-sensitized TiO{sub 2} nanotube arrays by doping with Zn{sup 2+} and decorating with ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Chen, Chong, E-mail: chongchen@henu.edu.cn [Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004 (China); School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Wang, Lei; Li, Fumin; Ling, Lanyu [Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng 475004 (China); School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

2014-08-01

The Zn-doped TiO{sub 2} nanotube arrays (TNTs) decorated with ZnO nanoparticles have been prepared via electrochemical anodization and immersing method. Furthermore, the CdS quantum dots (QDs) were deposited on the prepared Zn-doped TNTs-ZnO thin films by chemical bath deposition (CBD) method to fabricate the CdS QDs-sensitized Zn-doped TNTs-ZnO photoelectrodes. The nanostructure, morphology, optical properties and electrochemical properties of the CdS/Zn-doped TNTs-ZnO photoelectrode with comparison to those of the CdS/TNTs photoelectrodes were investigated. It has been found that the Zn-doped TNTs-ZnO photoelectrodes significantly increased the UV–vis light absorption of the CdS/Zn-doped TNTs-ZnO photoelectrodes and reduced the charge recombination at the surfaces of the CdS/Zn-doped TNTs-ZnO photoelectrodes. As a consequence, when the Zn-doped TNTs-ZnO film was adopted instead of the plain TNTs film, the light-chemical energy conversion efficiency of the CdS/Zn-doped TNTs-ZnO photoelectrode was much improved compared with the CdS/TNTs photoelectrode. A maximum energy conversion efficiency achieved for the CdS/Zn-doped TNTs-ZnO photoelectrode is 3.86%, which is a 17% improvement compared with the maximum energy conversion efficiency of 3.29% achieved for the CdS/TNTs photoelectrodes. - Highlights: • The CdS/Zn-doped TNTs-ZnO photoelectrodes were synthesized. • The optical properties and photochemical properties were investigated. • The energy conversion efficiency depends on the Zn doping concentration. • The energy conversion efficiency was improved by the Zn doping.

Effect of chlorine doping on the structural, morphological, optical and electrical properties of spray deposited CdS thin films

Directory of Open Access Journals (Sweden)

T. Sivaraman

2015-10-01

Full Text Available CdS and chlorine doped CdS (CdS:Cl thin films with different Cl-doping levels (0, 2, 4, 6 and 8 at% have been deposited on glass substrates by a spray pyrolysis technique using a perfume atomizer. The effect of Cl doping on the structural, morphological, optical and electrical properties of the films was investigated. XRD patterns revealed that all the films exhibit hexagonal crystal structure with a preferential orientation along the (0 0 2 plane irrespective of the Cl doping level. The particle size value decreases from 22.03 nm to 18.12 nm with increase in Cl concentration. Optical band gap is blue-shifted from 2.48 eV to 2.73 eV with increase in Cl doping concentration. All the films have resistivity in the order of 104 Ω cm. The obtained results confirm that chlorine as an anionic dopant material can enhance the physical properties of CdS thin films to a large extent.

Sol-gel synthesis of Cu-doped p-CdS nanoparticles and their analysis as p-CdS/n-ZnO thin film photodiode

Science.gov (United States)

Arya, Sandeep; Sharma, Asha; Singh, Bikram; Riyas, Mohammad; Bandhoria, Pankaj; Aatif, Mohammad; Gupta, Vinay

2018-05-01

Copper (Cu) doped p-CdS nanoparticles have been synthesized via sol-gel method. The as-synthesized nanoparticles were successfully characterized and implemented for fabrication of Glass/ITO/n-ZnO/p-CdS/Al thin film photodiode. The fabricated device is tested for small (-1 V to +1 V) bias voltage. Results verified that the junction leakage current within the dark is very small. During reverse bias condition, the maximum amount of photocurrent is obtained under illumination of 100 μW/cm2. Electrical characterizations confirmed that the external quantum efficiency (EQE), gain and responsivity of n-ZnO/p-CdS photodiode show improved photo response than conventional p-type materials for such a small bias voltage. It is therefore revealed that the Cu-doped CdS nanoparticles is an efficient p-type material for fabrication of thin film photo-devices.

A facile synthesis and spectral characterization of Cu{sup 2+} doped CdO/ZnS nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Joyce Stella, R.; Thirumala Rao, G.; Babu, B.; Pushpa Manjari, V. [Department of Physics, University College of Sciences, Acharya Nagarjuna University, Nagarjuna Nagar, AP 522510 (India); Reddy, Ch. Venkata; Shim, Jaesool [School of Mechanical Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Ravikumar, R.V.S.S.N., E-mail: rvssn@yahoo.co.in [Department of Physics, University College of Sciences, Acharya Nagarjuna University, Nagarjuna Nagar, AP 522510 (India)

2015-06-15

A facile two-step method is demonstrated for the preparation of Cu{sup 2+} doped CdO/ZnS nanocomposite. Systematic investigations like X-ray diffraction (XRD), Scanning electron microscopy (SEM) with EDS, transmission electron microscopy (TEM), FT-IR, electron paramagnetic resonance (EPR), optical absorption, photoluminescence (PL) and magnetic studies are carried out for the prepared material. From powder XRD, the nanocomposites are comprised for cubic phase of both CdO and ZnS in a close contact with each other. The ground state wave function of dopant ions has been estimated from EPR studies. Optical and EPR data confirm that doped Cu{sup 2+}ions occupy rhombically distorted octahedral sites with the host material. Due to doping, band gap has been changed and blue shifts occurred in PL. Magnetic measurements indicate a possible ferromagnetic response, associated to the exchange interaction between local spin-polarized electrons of Cu{sup 2+} ions and conductive electrons. - Graphical abstract: M–H curve of Cu{sup 2+} doped CdO–ZnS nanocomposites. The magnetic properties of Cu{sup 2+} doped CdO/ZnS nanocomposite has been investigated using vibrating sample magnetometer given as magnetization and hysteresis (M–H) curve. The magnetization curve with noticeable coercivity of M–H loop clearly indicate the existence of ferromagnetic ordering in Cu{sup 2+} doped CdO/ZnS nanocomposite at room temperature. According to the Ruderman–Kittel–Kasuya–Yosida (RKKY) theory, the exchange interaction between local spin-polarized electrons (such as the electrons of Cu{sup 2+} ions) and conductive electrons is the main cause that leads to the ferromagnetism. Coercivity (Hc) of the field is about 98 Oe, saturation magnetization (Ms) and remnant magnetization (Mr) of present sample is estimated to be 15.8×10{sup −3} and 1.43×10{sup −3} emu/g respectively. The ferromagnetism observed in the prepared material is not commencing with other impurities but expected to

Arsenic complexes optical signatures in As-doped HgCdTe

Energy Technology Data Exchange (ETDEWEB)

Gemain, F.; Robin, I. C.; Brochen, S.; Ballet, P.; Gravrand, O.; Feuillet, G. [CEA-LETI Minatec Campus, 17 rue des Martyrs, 38000 Grenoble (France)

2013-04-08

In this paper, the optical signatures of arsenic complexes in As-doped HgCdTe samples grown by molecular beam epitaxy are clearly identified using comparison between photoluminescence spectra, Extended X-Ray Absorption Fine Structure, and Hall measurements. The ionization energies of the different complexes are measured both by photoluminescence and Hall measurements.

Arsenic complexes optical signatures in As-doped HgCdTe

International Nuclear Information System (INIS)

Gemain, F.; Robin, I. C.; Brochen, S.; Ballet, P.; Gravrand, O.; Feuillet, G.

2013-01-01

In this paper, the optical signatures of arsenic complexes in As-doped HgCdTe samples grown by molecular beam epitaxy are clearly identified using comparison between photoluminescence spectra, Extended X-Ray Absorption Fine Structure, and Hall measurements. The ionization energies of the different complexes are measured both by photoluminescence and Hall measurements.

p-type doping efficiency in CdTe: Influence of second phase formation

Science.gov (United States)

McCoy, Jedidiah J.; Swain, Santosh K.; Sieber, John R.; Diercks, David R.; Gorman, Brian P.; Lynn, Kelvin G.

2018-04-01

Cadmium telluride (CdTe) high purity, bulk, crystal ingots doped with phosphorus were grown by the vertical Bridgman melt growth technique to understand and improve dopant solubility and activation. Large net carrier densities have been reproducibly obtained from as-grown ingots, indicating successful incorporation of dopants into the lattice. However, net carrier density values are orders of magnitude lower than the solubility of P in CdTe as reported in literature, 1018/cm3 to 1019/cm3 [J. H. Greenberg, J. Cryst. Growth 161, 1-11 (1996) and R. B. Hall and H. H. Woodbury, J. Appl. Phys. 39(12), 5361-5365 (1968)], despite comparable starting charge dopant densities. Growth conditions, such as melt stoichiometry and post growth cooling, are shown to have significant impacts on dopant solubility. This study demonstrates that a significant portion of the dopant becomes incorporated into second phase defects as compounds of cadmium and phosphorous, such as cadmium phosphide, which inhibits dopant incorporation into the lattice and limits maximum attainable net carrier density in bulk crystals. Here, we present an extensive study on the characteristics of these second phase defects in relation to their composition and formation kinetics while providing a pathway to minimize their formation and enhance solubility.

Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

International Nuclear Information System (INIS)

Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G.

1995-01-01

Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author)

Study of high mobility carriers in Ni-doped CdO films

Indian Academy of Sciences (India)

Cadmium oxide (CdO) doped with different amounts of nickel ion thin films have been prepared on silicon and glass .... glass substrate have [111] energetically preferred orientation growth, which is ... Bragg angle of the considered (111) reflection. ... boundaries. .... (figure 3), which means that the grain or crystallite bound-.

Dye sensitization of antimony-doped CdS photoelectrochemical solar cell

Energy Technology Data Exchange (ETDEWEB)

El Zayat, M.Y.; Saed, A.O.; El-Dessouki, M.S. [Department of Physics, Faculty of Science, Cairo University, Giza (Egypt)

2002-01-31

Sb-doped CdS single crystal was used as a photoanode to fabricate a photoelectrochemical solar (PECS) cell. The three organic dyes; eosin, thymol blue and rhodamin 6G were used as sensitizers in (PECS) cell. In the absence of the dye, the results showed that with Sb-doped CdS single crystal electrode, a higher power conversion efficiency 9.27% has been achieved compared to 5.7-7.4% for pure crystal. Application of the dye in PECS cell increases the efficiency to about 13%. The efficiency reaches its maximum value when the dye concentration is (2.5x10{sup -5})M, sufficient to cover the surface of the semiconductor electrode with a continuous monolayer of the dye. Exceeding this value resulted in a gradual decrease of the efficiency from its maximum value. Mott-Schottky plots gave a doping density of 3.14x10{sup 17}cm{sup -3} and a space charge width of 4.95x10{sup -6}cm for the sample used. A flat-band potential equal to -0.84V, independent of both frequency and pH, was also predicted. Cyclic voltammetry (c.v.) measurements showed an anodic current peak at 0.4V vs. SCE. The disappearance of this peak after excess addition of the reducing agent Na{sub 2}S, indicates that this peak is due to the PEC corrosion of the semiconductor electrode.

Improved performance of CdS/CdSe quantum dot-sensitized solar cells using Mn-doped PbS quantum dots as a catalyst in the counter electrode

International Nuclear Information System (INIS)

Kim, Byung-Man; Son, Min-Kyu; Kim, Soo-Kyoung; Hong, Na-Yeong; Park, Songyi; Jeong, Myeong-Soo; Seo, Hyunwoong; Prabakar, Kandasamy; Kim, Hee-Je

2014-01-01

Highlights: • PbS QDs synthesized using the SILAR method act not only as the electrochemical catalysts but as donors providing additional electrons under illumination. • The electrochemical and optical properties of the PbS QDs were enhanced considerably after Mn 2+ doping. • The electron supply from the counter electrode was significantly activated by Mn 2+ doping, improving the performance of QDSSC. - Abstract: This study reports the enhanced catalytic ability of Mn-doped PbS QDs synthesized using a successive ionic layer adsorption and reaction (SILAR) method for quantum dot-sensitized solar cells (QDSSCs). Electrochemical and optical analysis of each material showed that the catalytic ability of the PbS electrode was improved significantly by Mn 2+ doping. Two factors can explain this behavior. The first is that intentional impurities have an impact on the structure of the host material, such as increases in surface roughness. The other is that dopants create new energy states that delay the exciton recombination time and allow charge separation to be activated. As a result, the photoelectron supply from the counter electrode is accelerated, resulting in vigorous redox reactions at the polysulfide electrolyte. The performance of the CdS/CdSe QDSSC using a Mn-doped PbS counter electrode was compared with those using the Pt and PbS counter electrodes. Finally, a power conversion efficiency of 3.61% was achieved with the Mn-doped PbS counter electrode (V OC = 0.61 V, J SC = 11.67 mA cm −2 , FF = 0.51) under one sun illumination (100 mW cm −2 ), which is ∼40% higher than that of CdS/CdSe QDSSCs with the bare PbS counter electrode

Enhanced photovoltaic performance of quantum dot-sensitized solar cells with a progressive reduction of recombination using Cu-doped CdS quantum dots

International Nuclear Information System (INIS)

Muthalif, Mohammed Panthakkal Abdul; Lee, Young-Seok; Sunesh, Chozhidakath Damodharan; Kim, Hee-Je; Choe, Youngson

2017-01-01

Highlights: • Cu-doped CdS QDs were deposited on TiO_2 by SILAR method. • Cu-doped CdS electrodes contributes reduction of charge recombination and longer electron lifetime. • A promising power conversion efficiency of 3% is obtained for the Cu-doped CdS Quantum dot sensitized solar cell. - Abstract: In this article, we have systematically probed the effect of Cu-doping in CdS quantum dots (QDs) to enhance the photovoltaic performance of the quantum dot-sensitized solar cells (QDSSCs). The Cu-doped CdS photoanodes were prepared by successive ionic layer adsorption and reaction (SILAR) method and the corresponding cell devices were fabricated using CuS counter electrodes with a polysulfide electrolyte. The photovoltaic performance results demonstrate that 3 mM Cu-doped CdS QDs based QDSSCs exhibit the efficiency (η) of 3% including J_S_C = 9.40 mA cm"−"2, V_O_C = 0.637 V, FF = 0.501, which are higher than those with bare CdS (η = 2.05%, J_S_C = 7.12 mA cm"−"2, V_O_C = 0.588 V, FF = 0.489). The structural, topographical and optical properties of the thin films have been studied with the help of X-ray diffraction pattern (XRD), atomic force microscopy (AFM) and UV–vis spectrophotometer. Electrochemical impedance spectroscopy (EIS) and open circuit voltage decay (OCVD) measurements indicate that Cu-dopant can inhibit the charge recombination at the photoanode/electrolyte interface and extend the lifetime of electrons. These results reveal that incorporation of copper metal in CdS QDs is a simple and effective method to improve the photovoltaic properties of QDSSCs.

Enhanced photovoltaic performance of quantum dot-sensitized solar cells with a progressive reduction of recombination using Cu-doped CdS quantum dots

Energy Technology Data Exchange (ETDEWEB)

Muthalif, Mohammed Panthakkal Abdul [Department of Polymer Science and Chemical Engineering, Pusan National University, Geumjeong-Ku, Jangjeong-Dong, Busan 609-735 (Korea, Republic of); Lee, Young-Seok [School of Electrical Engineering, Pusan National University, Geumjeong-Ku, Jangjeong-Dong, Busan 609-735 (Korea, Republic of); Sunesh, Chozhidakath Damodharan [Department of Polymer Science and Chemical Engineering, Pusan National University, Geumjeong-Ku, Jangjeong-Dong, Busan 609-735 (Korea, Republic of); Kim, Hee-Je [School of Electrical Engineering, Pusan National University, Geumjeong-Ku, Jangjeong-Dong, Busan 609-735 (Korea, Republic of); Choe, Youngson, E-mail: choe@pusan.ac.kr [Department of Polymer Science and Chemical Engineering, Pusan National University, Geumjeong-Ku, Jangjeong-Dong, Busan 609-735 (Korea, Republic of)

2017-02-28

Highlights: • Cu-doped CdS QDs were deposited on TiO{sub 2} by SILAR method. • Cu-doped CdS electrodes contributes reduction of charge recombination and longer electron lifetime. • A promising power conversion efficiency of 3% is obtained for the Cu-doped CdS Quantum dot sensitized solar cell. - Abstract: In this article, we have systematically probed the effect of Cu-doping in CdS quantum dots (QDs) to enhance the photovoltaic performance of the quantum dot-sensitized solar cells (QDSSCs). The Cu-doped CdS photoanodes were prepared by successive ionic layer adsorption and reaction (SILAR) method and the corresponding cell devices were fabricated using CuS counter electrodes with a polysulfide electrolyte. The photovoltaic performance results demonstrate that 3 mM Cu-doped CdS QDs based QDSSCs exhibit the efficiency (η) of 3% including J{sub SC} = 9.40 mA cm{sup −2}, V{sub OC} = 0.637 V, FF = 0.501, which are higher than those with bare CdS (η = 2.05%, J{sub SC} = 7.12 mA cm{sup −2}, V{sub OC} = 0.588 V, FF = 0.489). The structural, topographical and optical properties of the thin films have been studied with the help of X-ray diffraction pattern (XRD), atomic force microscopy (AFM) and UV–vis spectrophotometer. Electrochemical impedance spectroscopy (EIS) and open circuit voltage decay (OCVD) measurements indicate that Cu-dopant can inhibit the charge recombination at the photoanode/electrolyte interface and extend the lifetime of electrons. These results reveal that incorporation of copper metal in CdS QDs is a simple and effective method to improve the photovoltaic properties of QDSSCs.

Effect of boron-doping on the luminescent and electrical properties of a CdS/Si heterostructure based on Si nanoporous pillar array

Energy Technology Data Exchange (ETDEWEB)

Yan, Ling Ling [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China); College of Physics and Chemistry, Henan Polytechnic University, Jiaozuo 454000 (China); Wang, Xiao Bo [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China); College of Physics and Electrical Engineering, Anyang Normal University, Anyang 455000 (China); Cai, Xiao Jun [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China); Li, Xin Jian, E-mail: lixj@zzu.edu.cn [Department of Physics and Laboratory of Material Physics, Zhengzhou University, Zhengzhou 450052 (China)

2015-05-25

Highlights: • B-doped CdS/Si-NPA heterostructure was prepared by a CBD method. • B-doping does not affect the crystal structure and surface morphology of CdS/Si-NPA. • The optical/electrical properties of CdS/Si-NPA could be tuned by changing [B]/[Cd] ratio. • CdS/Si-NPA with optimal physical properties could be prepared with [B]/[Cd] = 0.01. • The method may find applications in preparing CdS/Si-NPA devices with high device performances. - Abstract: Using silicon nanoporous pillar array (Si-NPA) as substrates and boric acid as dopant source, a series of CdS/Si nanoheterostructures were prepared by growing B-doped CdS thin films on Si-NPA via a chemical bath deposition (CBD) method. The structural, optical and electrical properties of CdS/Si-NPA were studied as a function of the [B]/[Cd] ratio of the initial CBD solutions. Our results disclosed that B concentration could be tuned effectively through changing the ratio of [B]/[Cd], which would bring large variation on the optical and electrical properties of CdS/Si-NPA without affecting its crystal structure and surface morphology. The samples with optimal optical and electrical properties were prepared with [B]/[Cd] = 0.01, in which the physical properties of relatively strong light absorption, small electrical resistivity, low turn-on voltage, small leakage current density and high breakdown voltage could be obtained. These results indicated that B-doping might be an effective path for promoting the performance of the optoelectronic devices based on CdS/Si-NPA.

Enhanced sunlight-driven photocatalytic performance of Bi-doped CdMoO4 benefited from efficient separation of photogenerated charge pairs

Science.gov (United States)

Huang, Jiao; Liu, Huanhuan; Zhong, Junbo; Yang, Qi; Chen, Jiufu; Li, Jianzhang; Ma, Dongmei; duan, Ran

2018-06-01

In this paper, to further boost the photocatalytic performance of CdMoO4, Bi3+ was successfully doped into CdMoO4 by a facile microwave hydrothermal method. The Bi-doped CdMoO4 photocatalysts prepared were characterized by Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), electron spin-resonance (ESR) and surface photovoltage spectroscopy (SPS). The results exhibit that doping Bi3+ into CdMoO4 remarkably boosts the separation rate of photoinduced charge pairs and the specific surface area, decrease the crystal size, narrows the band gap of the CdMoO4 and induces the binding energy shift of Cd, all these advantageous factors result in the promoted photocatalytic performance of CdMoO4. Using rhodamine B (RhB) as model toxic pollutant, the photocatalytic activities of the photocatalysts were evaluated under a 500 W Xe lamp irradiation. When the molar ratio of Bi/Cd is 0.2%, Bi-CdMoO4 prepared displays the best photocatalytic performance, the photocatalytic performance of the 0.2% sample is more than twice of that of the reference CdMoO4.

Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

Energy Technology Data Exchange (ETDEWEB)

Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G. [Physikalisches Institut der Uniwersitaet Wuerzburg, Wuerzburg (Germany)

1995-12-31

Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author). 5 refs, 3 figs, 1 tab.

Observation of long phase-coherence length in epitaxial La-doped CdO thin films

Science.gov (United States)

Yun, Yu; Ma, Yang; Tao, Songsheng; Xing, Wenyu; Chen, Yangyang; Su, Tang; Yuan, Wei; Wei, Jian; Lin, Xi; Niu, Qian; Xie, X. C.; Han, Wei

2017-12-01

The search for long electron phase-coherence length, which is the length that an electron can keep its quantum wavelike properties, has attracted considerable interest in the last several decades. Here, we report the long phase-coherence length of ˜3.7 μm in La-doped CdO thin films at 2 K. Systematical investigations of the La doping and the temperature dependences of the electron mobility and the electron phase-coherence length reveal contrasting scattering mechanisms for these two physical properties. Furthermore, these results show that the oxygen vacancies could be the dominant scatters in CdO thin films that break the electron phase coherence, which would shed light on further investigation of phase-coherence properties in oxide materials.

Size effect on the SHG properties of Cu-doped CdI2 nanocrystals

International Nuclear Information System (INIS)

Miah, M. Idrish

2009-01-01

Because the optically induced second harmonic generation (SHG) is prevented by symmetry in a centrosymmetric material, one needs to form noncentrosymmetric processes in order to observe the SHG. However, one of the efficient ways to enhance the noncentrosymmetricity of a material is to dope it with an appropriate impurity and amount. We grow Cu-doped CdI 2 layered nanocrystal structures from the mixture of CdI 2 and CuI using the standard Bridgman-Stockbarger method and investigate the nano-confined effects by studying the second-order optical effect via the measurements of SHG. The second-order susceptibility for the nanocrystals is calculated and the values at liquid helium temperature range from 0.38 to 0.83 pm V -1 for the thicknesses of 10-0.8 nm respectively. The size dependence demonstrates the nano-sized quantum-confined effect with a clear increase in the SHG with decreasing the thickness of the nanocrystal or crystal temperature. Since the local electron-phonon anharmonicity is described by third-order rank tensors in disordered systems, the SHG is very similar to that one introduced for the third-order optical susceptibility. It has been confirmed by observing the large photoluminescent yield of the pure crystals. The Raman scattering spectra taken for thin nanocrystals confirm the phonon modes originating from interlayer phonons crucially responsible for the observed effects. The obtained results show that the Cu-doped CdI 2 layered nanocrystals are promising materials for applications in optoelectronic nano-devices.

Structural, optical and photovoltaic properties of P3HT and Mn-doped CdS quantum dots based bulk hetrojunction hybrid layers

Science.gov (United States)

Jabeen, Uzma; Adhikari, Tham; Pathak, Dinesh; Shah, Syed Mujtaba; Nunzi, Jean-Michel

2018-04-01

Cadmium sulphide (CdS) and Mn-doped CdS nanocrystals were synthesized by co-precipitation method. The nanocrystals were characterized by Fluorescence, Fourier Transformed Infra-red Spectrometer (FTIR), UV-Visible, X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), Field Emission Scanning Electron Microscope (FESEM), and High Resolution Transmission Electron Microscope (HRTEM). A considerable blue shift of absorption band with respect to the cadmium sulphide was observed by the Mn concentration (0.5 M) in the doped sample with decreasing the size of nanocrystals. Other reason for this may be Mn doping. Subsequently the band gap was altered from 2.11 to 2.21 eV due to quantum confinement effect. Scanning electron microscope supplemented with EDAX was operated to find grain size and chemical composition of the synthesized nanomaterials. The PL spectrum of Mn-doped CdS nanocrystals displays three PL bands the first one, within the range of 500 nm and the second band at 537 nm, and the third one around 713 nm is labelled red band emission due to attributed to a 4T1→6A1 transition within the 3d shell of divalent manganese. XRD analysis showed that the material was in cubic crystalline state. A comparative study of surfaces of un-doped and metal doped CdS nanocrystals were investigated using X-ray Photoelectron Spectroscopy (XPS). The synthesized nanomaterial in combination with polymer, poly (3-hexyl thiophene) was operated in the construction of photovoltaic cells. The photovoltaic devices with CdS nanocrystals exhibited power conversion efficiency of 0.34% without annealing and 0.38% with annealing. However, the power conversion efficiency was enhanced by a factor of 0.35 without annealing and 0.42 with annealing with corporation of Mn impurity in CdS lattice. Atomic Force Microscopy was employed for morphology and packing behavior of blend of nanocrystals with organic polymer.

Structure and thermoelectric property of Te doped paracostibite CoSb1-xTexS compounds

Science.gov (United States)

You, Yonghui; Su, Xianli; Liu, Wei; Yan, Yonggao; Fu, Jiefei; Cheng, Xin; Zhang, Cheng; Tang, Xinfeng

2018-06-01

Paracostibite (CoSbS), a newly developed thermoelectric material, has aroused lots of interest due to its highly earth abundant and inexpensive constituent elements and potential application for thermoelectric power generation in the intermediate temperature range. Herein, a series of CoSb1-xTexS (x = 0-0.09) compounds were prepared by vacuum melting and annealing followed by SPS processing, and the effects of Te doping on the structure and thermoelectric properties were systematically investigated. Doping Te on the Sb site increases the carrier concentration up to 7.24 × 1020 cm-3 for CoSb0.93Te0.07S compound which is several orders of magnitude higher than that of un-doped CoSbS, and enhances the power factor. The maximum power factor of 14.07 μW cm-1 K-2 is attained at 900 K. Concomitantly, doping with Te on the Sb site leads to effective scattering of heat carrying phonon, accompanying with a strong suppression of the thermal conductivity with the increase of Te content, resulting in an increase of the ZT. A maximum ZT of 0.43 at 900 K is attained for CoSb0.93Te0.07S compound, which is 139% higher than that of un-doped CoSbS compound.

Effect of CdS Growth Time on the Optical Properties of One-Pot Preparation of CdS-Ag2S Binary Compounds

Science.gov (United States)

Karimipour, M.; Izadian, L.; Molaei, M.

2018-02-01

CdS-Ag2S binary nanoparticles were synthesized using a facile one-pot microwave irradiation method. The effect of initial nucleation of CdS quantum dots (QDs) using 3 min, 5 min, and 7 min of microwave irradiation on the optical properties of the final compound was studied. The composition and crystal structure of the compounds were verified using energy dispersive x-ray spectroscopy and x-ray diffraction. They revealed that existence of Ag and Cd elements with an atomic ratio of 0.19 crystalizes in the form of monoclinic Ag2S and hexagonal CdS. Scanning electron microscope images showed a spherical morphology of the resultant compound, and transmission electron microscope images showed the formation of fine particles of CdS-Ag2S composites with an average size of 5-7 nm and 10-14 nm for CdS and Ag2S, respectively. Photoluminescence spectroscopy revealed that the initial growth time of CdS has a crucial effect on the emission of binary compounds such that for 3 min and 5 min of irradiation of CdS solution, the binary compound obtains strong red and considerable near-IR emission (850 nm), but for longer time, it rapidly quenches. The results indicate that the strong red emission can be tuned from 600 nm up to 700 nm with prolonging nucleation time of CdS. This study also emphasized that the origin of red emission strongly depends on the size and defects created in the CdS QDs.

Effect of indium doping level on certain physical properties of CdS films deposited using an improved SILAR technique

Energy Technology Data Exchange (ETDEWEB)

Ravichandran, K., E-mail: kkr1365@yahoo.com [P.G. and Research Department of Physics, AVVM Sri Pushpam College (Autonomous), Poondi, Thanjavur-613 503, Tamil Nadu (India); Senthamilselvi, V. [P.G. and Research Department of Physics, AVVM Sri Pushpam College (Autonomous), Poondi, Thanjavur-613 503, Tamil Nadu (India); Department of Physics, Kunthavai Naachiyaar Government College for Women (Autonomous), Thanjavur-613 007, Tamil Nadu (India)

2013-04-01

The influence of indium (In) doping levels (0, 2, …, 8 at.%) on certain physical properties of cadmium sulphide (CdS) thin films deposited using an improved successive ionic layer adsorption and reaction (ISILAR) method has been studied. In this improved SILAR technique, a fresh anionic solution was introduced after a particular number of dipping cycles in order to achieve good stoichiometry. All the deposited films exhibited cubic phase with (1 1 1) plane as preferential orientation. The calculated crystallite size values are found to be decreased from 54.80 nm to 23.65 nm with the increase in In doping level. The optical study confirmed the good transparency (80%) of the film. A most compact and pinhole free smooth surface was observed for the CdS films with 8 at.% of In doping level. The perceived photoluminescence (PL) bands endorsed the lesser defect crystalline nature of the obtained CdS:In films. The chemical composition analysis (EDAX) showed the near stoichiometric nature of this ISILAR deposited CdS:In films.

Effect of indium doping level on certain physical properties of CdS films deposited using an improved SILAR technique

International Nuclear Information System (INIS)

Ravichandran, K.; Senthamilselvi, V.

2013-01-01

The influence of indium (In) doping levels (0, 2, …, 8 at.%) on certain physical properties of cadmium sulphide (CdS) thin films deposited using an improved successive ionic layer adsorption and reaction (ISILAR) method has been studied. In this improved SILAR technique, a fresh anionic solution was introduced after a particular number of dipping cycles in order to achieve good stoichiometry. All the deposited films exhibited cubic phase with (1 1 1) plane as preferential orientation. The calculated crystallite size values are found to be decreased from 54.80 nm to 23.65 nm with the increase in In doping level. The optical study confirmed the good transparency (80%) of the film. A most compact and pinhole free smooth surface was observed for the CdS films with 8 at.% of In doping level. The perceived photoluminescence (PL) bands endorsed the lesser defect crystalline nature of the obtained CdS:In films. The chemical composition analysis (EDAX) showed the near stoichiometric nature of this ISILAR deposited CdS:In films.

Hydrostatic pressure study of MBE CdMnTe doped bromine

International Nuclear Information System (INIS)

Szczytko, J.; Wasek, D.; Przybytek, J.; Baj, M.; Waag, A.

1995-01-01

We present Hall effect and resistivity measurements as a function of pressure performed on MBE-grown Cd 1-x Mn x Te (with x=0.14) layer doped with bromine. The experimental data were analysed using positive and negative U model of Br centers. We found that both models could reproduce the experimental points, but in the case of positive U modes - only under assumption that the sample was completely uncompensated. (author)

High mobility 2D electron gas in CdTe/CdMgTe heterostructures

International Nuclear Information System (INIS)

Karczewski, G.; Jaroszynski, J.; Kurowski, M.; Barcz, A.; Wojtowicz, T.; Kossut, J.

1997-01-01

We report on iodine doping of molecular beam epitaxy (MBE)-grown Cd(Mn)Te quasi-bulk films and modulation-doped CdTe/Cd 1-y Mg y Te two-dimensional (2D) single quantum well structures. Modulation doping with iodine of CdTe/Cd 1-y Mg y Te structures resulted in fabrication of a 2D electron gas with mobility exceeding 10 5 cm 2 /(Vs). This is the highest mobility reported in wide-gap II-VI materials

Chemical composition of cadmium selenochromite crystals doped with indium, silver and gallium

International Nuclear Information System (INIS)

Bel'skij, N.K.; Ochertyanova, L.I.; Shabunina, G.G.; Aminov, T.G.

1985-01-01

The high accuracy chemical analysis Which allows one to observe doping effect on the cadmium selenochromite crystal composition is performed. The problem on the possibility of impurity atom substitution for basic element is considered on the basis of data of atomic-absorption analysis of doped crystals. The crystals of cadmium selenochromite doped with indium by chromium to cadmium ratio are distributed into two groups and probably two types of substitution take place. At 0.08-1.5 at.% indium concentrations the Cr/Cd ratio >2. One can assume that indium preferably takes cadmium tetrahedral positions whereas at 1.5-2.5 at. % concentrations the Cr/Cd ratio =2 and cadmium is substituted for silver which does not contradict crystallochemical and physical properties of this compound. In crystals with gallium the Cr/Cd ratio <2. Gallium preferably substitutes chromium

Electric-field gradients at the $^{111}In$ and $^{111m}Cd$ sites in undoped and Mg-doped $LiNbO_{3}$

CERN Document Server

Hauer, B; Marques, J G; Barradas, N P; Correia, J G; Agulló-López, F; Diéguez, E

1995-01-01

The quadrupole interaction of 111Cd in undoped (congruent) and Mg-doped LiNbO3 single crystals has been studied using the perturbed angular correlation technique after implantation of 111In and 111mCd. A stepwise-annealing procedure shows the lattice to be fully reconstructed at 773 K. Our results show that both In and Cd are in the Li position. Mg doping at 6 mol % does not have any effect on the lattice location of these impurities in LiNbO3.

Enthalpies of formation of Cd0.917Sr0.083, Cd0.857Sr0.143 and Cd0.667Sr0.333 intermetallic compounds

International Nuclear Information System (INIS)

Agarwal, Renu; Singh, Ziley

2008-01-01

Cadmium is expected to be the solvent for pyrochemical processing of the metallic nuclear fuel. Therefore, thermodynamic properties of cadmium with various fuel and clad elements are of interest. Enthalpies of formation of the intermetallic compounds of Cd-Sr system, Cd 0.917 Sr 0.083 , Cd 0.857 Sr 0.143 and Cd 0.667 Sr 0.333 were determined by precipitation using Calvet calorimeter. Enthalpies of formation of the compounds were found to be -3.05 ± 0.5 kJ mol -1 at 723 K, -14.2 ± 0.7 kJ mol -1 at 843 K and -28.4 ± 0.8 kJ mol -1 at 863 K, respectively. Enthalpies of formation of Cd 0.917 Sr 0.083 and Cd 0.857 Sr 0.143 were also determined by partial enthalpy of formation measurements and the values were found to be -3.9 ± 1.1 kJ mol -1 at 723 K and -13.42 ± 1.2 kJ mol -1 at 843 K, respectively. Miedema model was used to estimate the enthalpies of formation of these compounds and the estimated values were compared with the experimentally determined values

Hydrostatic pressure study of MBE CdMnTe doped bromine

Energy Technology Data Exchange (ETDEWEB)

Szczytko, J.; Wasek, D.; Przybytek, J.; Baj, M. [Institute of Experimental Physics, Warsaw University, Warsaw (Poland); Waag, A. [Physikalisches Institut, Universitaet Wuerzburg, Wuerzburg (Germany)

1995-12-31

We present Hall effect and resistivity measurements as a function of pressure performed on MBE-grown Cd{sub 1-x}Mn{sub x}Te (with x=0.14) layer doped with bromine. The experimental data were analysed using positive and negative U model of Br centers. We found that both models could reproduce the experimental points, but in the case of positive U modes - only under assumption that the sample was completely uncompensated. (author). 6 refs, 3 figs.

Halogen doping of II-VI semiconductors during molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A.; Litz, Th.; Fischer, F.; Heinke, H.; Scholl, S.; Hommel, D.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1994-04-14

Results on the halogen doping of CdTe, (CdMn)Te as well as (CdMg)Te thin films and quantum well structures are reported. The structures were grown by molecular beam epitaxy. The samples have been investigated by Van der Pauw, photoconductivity, X-ray diffraction, XPS and SIMS measurements. ZnCl[sub 2] and ZnBr[sub 2] have been used as dopant sources. Free carrier concentrations at room temperature above 10[sup 18] cm[sup -3] can easily be achieved for CdTe for a wide range of Cd/Te flux ratios and substrate temperatures. In the ternary alloys, the free carrier concentration decreases drastically with increasing x-values, despite a constant incorporation of the dopant species. In addition, persistent photoconductivity has been observed in n-type doped ternary thin films at low temperatures. The decrease of the free carrier concentration with x-value is common to other wide-gap ternary alloys, and the reason for it is discussed in the frame of DX-like deep donor impurities in ternary II-VI compounds. In first experiments on planar halogen doping of CdTe, a doping level of 5x10[sup 18] cm[sup -3] could be reached in the doped regions, the highest value ever reported for CdTe. A clear influence of dopant incorporation on the structural quality of CdTe thin films has been seen even for dopant concentrations of as low as 10[sup 18] cm[sup -3]. The FWHM of the rocking curves decreased by a factor of 2 with increasing dopant incorporation. SIMS as well as XPS measurements demonstrate that the Cl/Zn and Br/Zn ratio in the doped films is 2/1, but no chemical shift corresponding to Zn-Cl or Zn-Br bonds could be detected. A model for the incorporation of the halogens is proposed on the basis of these results

Ethanol Sensor of CdO/Al2O3/CeO2 Obtained from Ce-DOPED Layered Double Hydroxides with High Response and Selectivity

Science.gov (United States)

Xu, Dongmei; Guan, Meiyu; Xu, Qinghong; Guo, Ying; Wang, Yao

2013-04-01

In this paper, Ce-doped CdAl layered double hydroxide (LDH) was first synthesized and the derivative CdO/Al2O3/CeO2 composite oxide was prepared by calcining Ce-doped CdAl LDH. The structure, morphology and chemical state of the Ce doped CdAl LDH and CdO/Al2O3/CeO2 were also investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), solid state nuclear magnetic resonance (SSNMR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The gas sensing properties of CdO/Al2O3/CeO2 to ethanol were further studied and compared with CdO/Al2O3 prepared from CdAl LDH, CeO2 powder as well as the calcined Ce salt. It turns out that CdO/Al2O3/CeO2 sensor shows best performance in ethanol response. Besides, CdO/Al2O3/CeO2 possesses short response/recovery time (12/72 s) as well as remarkable selectivity in ethanol sensing, which means composite oxides prepared from LDH are very promising in gas sensing application.

High activity of Ag-doped Cd0.1Zn0.9S photocatalyst prepared by the hydrothermal method for hydrogen production under visible-light irradiation

Directory of Open Access Journals (Sweden)

Leny Yuliati

2014-05-01

Full Text Available Background: The hydrothermal method was used as a new approach to prepare a series of Ag-doped Cd0.1Zn0.9S photocatalysts. The effect of Ag doping on the properties and photocatalytic activity of Cd0.1Zn0.9S was studied for the hydrogen production from water reduction under visible light irradiation.Results: Compared to the series prepared by the co-precipitation method, samples prepared by the hydrothermal method performed with a better photocatalytic activity. The sample with the optimum amount of Ag doping showed the highest hydrogen production rate of 3.91 mmol/h, which was 1.7 times higher than that of undoped Cd0.1Zn0.9S. With the Ag doping, a red shift in the optical response was observed, leading to a larger portion of the visible light absorption than that of without doping. In addition to the larger absorption in the visible-light region, the increase in photocatalytic activity of samples with Ag doping may also come from the Ag species facilitating electron–hole separation.Conclusion: This study demonstrated that Ag doping is a promising way to enhance the activity of Cd0.1Zn0.9S photocatalyst.

Stimulation of the photoluminescent properties of CBD-CdS thin films achieved by structural modifications resulting from Ag{sup +} doping

Energy Technology Data Exchange (ETDEWEB)

Flores-Pacheco, A.; Contreras-Rascon, J.I.; Castillo, S.J.; Alvarez-Ramos, M.E. [Posgrado en Nanotecnologia, Departamento de Fisica, Universidad de Sonora, Hermosillo (Mexico); Diaz-Reyes, J. [Centro de Investigacion en Biotecnologia Aplicada, Instituto Politecnico Nacional, Tepetitla, Tlaxcala (Mexico); Angel-Vicente, P.D. [Instituto Mexicano del Petroleo, Direccion de Investigacion y Posgrado, Ciudad de Mexico (Mexico); Enriquez, J.P. [Centro de Investigacion y Desarrollo Tecnologico en Energias Renovables, Universidad de Ciencias y Artes de Chiapas, Tuxtla Gutierrez (Mexico)

2017-08-15

The present study details the changes in photoluminescence properties stimulated by the structural changes in consequence of doping the II-VI nanocomposite thin-film semiconductor cadmium sulfide (CdS) with the IB metallic ion Ag{sup +}. The synthesis of the matrix and doped semiconductors was performed using low-temperature chemical bath deposition (CBD). The doping percentage of the CdS matrix was determined by energy-dispersive X-ray spectroscopy (EDS) with a value around 3%. The crystallographic study shows a cubic (1 1 1) preferential growth plane for the undoped material. Both X-ray and HRTEM characterizations show the presence of a polycrystalline structure for the Ag{sup +}-doped sample. Measurements of particle size from HRTEM micrographs confirm quantum confinement with a reduction of the average particle size from 5.46 to 4.12 nm in the doped sample. The photoluminescence study shows intense downshifted emissions in the green range of the visible spectrum. This could be due to the shallow electron traps formed by crystalline defects in the lattice, which are induced by the metallic ion. This study also shows higher-energy emissions due to the decrease of the particle size below the effective CdS exciton Bohr radius. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Influence of Ag doping concentration on structural and optical properties of CdS thin film

International Nuclear Information System (INIS)

Kumar, Pragati; Saxena, Nupur; Gupta, Vinay; Agarwal, Avinash

2015-01-01

This work shows the influence of Ag concentration on structural properties of pulsed laser deposited nanocrystalline CdS thin film. X-ray photoelectron spectroscopy (XPS) studies confirm the dopant concentration in CdS films and atomic concentration of elements. XPS studies show that the samples are slightly sulfur deficient. GAXRD scan reveals the structural phase transformation from cubic to hexagonal phase of CdS without appearance of any phase of CdO, Ag 2 O or Ag 2 S suggesting the substitutional doping of Ag ions. Photoluminescence studies illustrate that emission intensity increases with increase in dopant concentration upto 5% and then decreases for higher dopant concentration

Influence of Ag doping concentration on structural and optical properties of CdS thin film

Energy Technology Data Exchange (ETDEWEB)

Kumar, Pragati, E-mail: pkumar.phy@gmail.com [Department of Physics, Bareilly College, Bareilly, 243 005, Uttar Pradesh (India); Department of Physics and Astrophysics, University of Delhi, Delhi, 110 007 (India); Saxena, Nupur; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi, 110 007 (India); Agarwal, Avinash [Department of Physics, Bareilly College, Bareilly, 243 005, Uttar Pradesh (India)

2015-05-15

This work shows the influence of Ag concentration on structural properties of pulsed laser deposited nanocrystalline CdS thin film. X-ray photoelectron spectroscopy (XPS) studies confirm the dopant concentration in CdS films and atomic concentration of elements. XPS studies show that the samples are slightly sulfur deficient. GAXRD scan reveals the structural phase transformation from cubic to hexagonal phase of CdS without appearance of any phase of CdO, Ag{sub 2}O or Ag{sub 2}S suggesting the substitutional doping of Ag ions. Photoluminescence studies illustrate that emission intensity increases with increase in dopant concentration upto 5% and then decreases for higher dopant concentration.

Efficiency Enhanced Colloidal Mn-Doped Type II Core/Shell ZnSe/CdS Quantum Dot Sensitized Hybrid Solar Cells

Directory of Open Access Journals (Sweden)

A. Jamshidi

2015-01-01

Full Text Available Colloidal Mn-doped ZnSe/CdS core/shell quantum dots (QDs are synthesized for the first time and employed as a strategy to boost the power conversion efficiency of quantum dot sensitized solar cells. By using Mn-doping as a band gap engineering tool for core/shell QDs an effective improvement of absorption spectra could be obtained. The mid-states generated by a proper Mn content alleviate carrier separation and enhance the electron injection rate, thus facilitating electron transport to the TiO2 substrate. It is demonstrated that a device constructed with 0.25% Mn-doped ZnSe/CdS leads to an enhancement of the electron injection rate and power conversion efficiency by 4 times and 1.3, respectively.

Size effect on the SHG properties of Cu-doped CdI{sub 2} nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

2009-12-15

Because the optically induced second harmonic generation (SHG) is prevented by symmetry in a centrosymmetric material, one needs to form noncentrosymmetric processes in order to observe the SHG. However, one of the efficient ways to enhance the noncentrosymmetricity of a material is to dope it with an appropriate impurity and amount. We grow Cu-doped CdI{sub 2} layered nanocrystal structures from the mixture of CdI{sub 2} and CuI using the standard Bridgman-Stockbarger method and investigate the nano-confined effects by studying the second-order optical effect via the measurements of SHG. The second-order susceptibility for the nanocrystals is calculated and the values at liquid helium temperature range from 0.38 to 0.83 pm V{sup -1} for the thicknesses of 10-0.8 nm respectively. The size dependence demonstrates the nano-sized quantum-confined effect with a clear increase in the SHG with decreasing the thickness of the nanocrystal or crystal temperature. Since the local electron-phonon anharmonicity is described by third-order rank tensors in disordered systems, the SHG is very similar to that one introduced for the third-order optical susceptibility. It has been confirmed by observing the large photoluminescent yield of the pure crystals. The Raman scattering spectra taken for thin nanocrystals confirm the phonon modes originating from interlayer phonons crucially responsible for the observed effects. The obtained results show that the Cu-doped CdI{sub 2} layered nanocrystals are promising materials for applications in optoelectronic nano-devices.

Effect of Zn doping on optical properties and photoconductivity of ...

Indian Academy of Sciences (India)

Keywords. Thin film; spray pyrolysis; tin sulfide; optical properties; photoluminescence; photoconductivity. 1. ... ber of compounds with CdI2 structure, has interesting proper- ties such .... STM images of 0, 2·5, 5 and 7·5 at% Zn-doped SnS2 films.

Luminescence of Ce doped oxygen crystalline compounds based on Hf and Ba

CERN Document Server

Borisevich, A E; Lecoq, P

2003-01-01

The luminescence properties of the Ce-doped hafnium and barium compounds have been investigated to determine their potential as heavy scintillation materials. Compounds have been prepared by solid state synthesis. All of them have shown a bright luminescence attributed to trivalent cerium. Emission bands are peaked in the 425-475nm spectral region at room temperature.

Cu-Doping Effects in CdI(2) Nanocrystals: The Role of Cu-Agglomerates.

Science.gov (United States)

Miah, M Idrish

2008-11-22

Cu-doping effects in CdI(2) nanocrystals are studied experimentally. We use the photostimulated second harmonic generation (PSSHG) as a tool to investigate the effects. It is found that the PSSHG increases with increasing Cu content up to 0.6% and then decreases due to the formation of the Cu-agglomerates. The PSSHG for the crystal with Cu content higher than 1% reduces to that for the undoped CdI(2) crystal. The results suggest that a crucial role of the Cu-metallic agglomerates is involved in the processes as responsible for the observed effects.

Cu-Doping Effects in CdI2Nanocrystals: The Role of Cu-Agglomerates

Directory of Open Access Journals (Sweden)

Miah M

2008-01-01

Full Text Available Abstract Cu-doping effects in CdI2nanocrystals are studied experimentally. We use the photostimulated second harmonic generation (PSSHG as a tool to investigate the effects. It is found that the PSSHG increases with increasing Cu content up to 0.6% and then decreases due to the formation of the Cu-agglomerates. The PSSHG for the crystal with Cu content higher than 1% reduces to that for the undoped CdI2crystal. The results suggest that a crucial role of the Cu-metallic agglomerates is involved in the processes as responsible for the observed effects.

Electrical characterization of CdTe grain-boundary properties from as processed CdTe/CdS solar cells

Energy Technology Data Exchange (ETDEWEB)

Woods, L.M.; Robinson, G.Y. [Colorado State Univ., Fort Collins, CO (United States); Levi, D.H.; Ahrenkiel, R.K. [National Renewable Energy Lab., Golden, CO (United States); Kaydanov, V. [Colorado School of Mines, Golden, CO (United States)

1998-09-01

An ability to liftoff or separate the thin-film polycrystalline CdTe from the CdS, without the use of chemical etches, has enabled direct electrical characterization of the as-processed CdTe near the CdTe/CdS heterointerface. The authors use this ability to understand how a back-contact, nitric-phosphoric (NP) etch affects the grain boundaries throughout the film. Quantitative determination of the grain-boundary barrier potentials and estimates of doping density near the grain perimeter are determined from theoretical fits to measurements of the current vs. temperature. Estimates of the bulk doping are determined from high-frequency resistivity measurements. The light and dark barrier potentials change after the NP etch, and the origin of this change is postulated. Also, a variable doping density within the grains of non-etched material has been determined. These results allow a semi-quantitative grain-boundary band diagram to be drawn that should aid in determining more accurate two-dimensional models for polycrystalline CdTe solar cells.

Spectroscopic study on the doping of polycrystalline CdTe layers for solar cells; Spektroskopische Untersuchungen zur Dotierung von polykristallinen CdTe-Schichten fuer Solarzellen

Energy Technology Data Exchange (ETDEWEB)

Kraft, Christian

2011-11-29

First in the present thesis the fundamental properties of CdTe are described. In the following it is discussed, how a CdTe solar cell is generally constructed, which specialities are to be regarded, and how an improvement of the actually reachable data of such a solar cell in view of the efficiency can be reached fundamentally and in then practical realization. In the third chapter the physical foundations of the most important methods are discussed, which are applied in the framework of this thesis for the analysis of the CdTe layers. The fourth chapter describes the details of the experiments of this thesis. The fifth chapter deals with the analysis of the photoluminescence of CdTe layers. Special attention is put on the analysis of the excitonic luminescence. The sixth chapter treats the implantation of CdTe layers with phosphor. The influence of phosphorus as dopant on the PL spectra of CdTe and the correponding characteristics of implanted solar cells are presented. Also the influence of radiation damages as consequence of the ion implantation is studied in this chapter by means of the analysis of differently thick absorber layers. In the seventh chapter finally a new procedure for the fabrication of solar cells on the base of CdTe as absorber material is introduced, which shall make possible to change the stoichiometry of cadmium mand tellurium specifically and to present additionally a suited material, in order to form the doping of CdTE a solar-cell material variably. The fundamental properties of the new facility are experimentally determined, and first solar cells are fabricated with this facility and analyzed. Also an in-situ doping with phosphorus is thereby performed and the result studied.

Mode-locked Er-doped fiber laser based on PbS/CdS core/shell quantum dots as saturable absorber.

Science.gov (United States)

Ming, Na; Tao, Shina; Yang, Wenqing; Chen, Qingyun; Sun, Ruyi; Wang, Chang; Wang, Shuyun; Man, Baoyuan; Zhang, Huanian

2018-04-02

Previously, PbS/CdS core/shell quantum dots with excellent optical properties have been widely used as light-harvesting materials in solar cell and biomarkers in bio-medicine. However, the nonlinear absorption characteristics of PbS/CdS core/shell quantum dots have been rarely investigated. In this work, PbS/CdS core/shell quantum dots were successfully employed as nonlinear saturable absorber (SA) for demonstrating a mode-locked Er-doped fiber laser. Based on a film-type SA, which was prepared by incorporating the quantum dots with the polyvinyl alcohol (PVA), mode-locked Er-doped operation with a pulse width of 54 ps and a maximum average output power of 2.71 mW at the repetition rate of 3.302 MHz was obtained. Our long-time stable results indicate that the CdS shell can effectively protect the PbS core from the effect of photo-oxidation and PbS/CdS core/shell quantum dots were efficient SA candidates for demonstrating pulse fiber lasers due to its tunable absorption peak and excellent saturable absorption properties.

Germanium Doping to Improve Carrier Mobility in CdO Films

Directory of Open Access Journals (Sweden)

A. A. Dakhel

2013-01-01

Full Text Available This investigation addresses the structural, optical, and electrical properties of germanium incorporated cadmium oxide (CdO : Ge thin films. The focus was on the improvement in carrier mobility to achieve high transparency for near-infrared light and low resistivity at the same time. The properties were studied using X-ray diffraction, SEM, spectral photometry, and Hall measurements. All CdO : Ge films were polycrystalline with high texture orientation along [111] direction. It was observed that it is possible to control the carrier concentration ( and mobility ( with Ge-incorporation level. The mobility could be improved to a highest value of  cm2/V·s with Ge doping of 0.25 wt% while maintaining the electrical resistivity as low as  Ω·cm and good transparency % in the NIR spectral region. The results of the present work proved to select Ge as dopant to achieve high carrier mobility with low resistivity for application in transparent conducting oxide (TCO field. Generally, the properties found make CdO : Ge films particularly interesting for the application in optoelectronic devices like thin-film solar cells.

Co+ -ion implantation induced doping of nanocrystalline CdS thin films: structural, optical, and vibrational properties

International Nuclear Information System (INIS)

Chandramohan, S.; Sarangi, S.N.; Majumder, S.; Som, T.; Kanjilal, A.; Sathyamoorthy, R.

2009-01-01

Full text: Transition metal (Mn, Fe, Co and Ni) doped CdS nanostructures and nanocrystalline thin films have attracted much attention due to their anticipated applications in magneto-optical, non-volatile memory and future spintronics devices. Introduction of impurities in substitutional positions is highly desirable for such applications. Ion implantation is known to provide many advantages over conventional methods for efficient doping and possibility of its seamless integration with device processing steps. It is not governed by equilibrium thermodynamics and offers the advantages of high spatial selectivity and to overcome the solubility limits. In this communication, we report on modifications of structural morphological, optical, and vibrational properties of 90 keV Co + -ion implanted CdS thin films grown by thermal evaporation. Co + -ion implantation was performed in the fluence range of 0.1-3.6x10 16 ions cm -2 These fluences correspond to Co concentration in the range of 0.34-10.8 at % at the peak position of profile. Implantation was done at an elevated temperature of 573 K in order to avoid amorphization and to enhance the solubility of Co ions in the CdS lattice. Films were characterized by glancing angle X-ray diffraction (GAXRD), atomic force microscopy (AFM), optical absorption, and micro-Raman spectroscopy. Implantation does not lead to any secondary phase formation either in the form of impurity or the metallic clusters. However, implantation improves the crystalline quality of the samples and leads to supersaturation of Co ions in the CdS lattice. Thus, nanocrystalline CdS thin films can be considered as a good radiation- resistant material, which can be employed for prolonged use in solar cells for space applications. The optical band gap is found to decrease systematically with increasing ion fluence from 2.39 to 2.28 eV. Implantation leads to agglomeration of grains and a systematic increase in the surface roughness. Both GAXRD and micro

Reactivity of silicon and germanium doped CNTs toward aromatic sulfur compounds: A theoretical approach

International Nuclear Information System (INIS)

Galano, Annia; Francisco-Marquez, Misaela

2008-01-01

Adsorption processes of thiophene and benzothiophene on pristine carbon nanotubes (CNTs), and on CNTs doped with Si or Ge, have been modeled with Density Functional. This is the first study on the chemical reactivity of such doped tubes. The calculated data suggest that the presence of silicon or germanium atoms in CNTs increases their reactivity toward thiophene, and benzothiophene. The adsorption of these species on pristine CNTs seems very unlikely to occur, while the addition products involving doped CNTs were found to be very stable, with respect to the isolated reactants, in terms of Gibbs free energy. Several of these adsorption processes were found to be significantly exergonic (ΔG < 0) in non-polar liquid phase. The results reported in this work suggest that Si and Ge defects on CNTs increase their reactivity toward unsaturated species, and could make them useful in the removal processes of aromatic sulfur compounds from oil-hydrocarbons. However, according to our results, CNTs doped with Si atoms are expected to be more efficient as aromatic sulfur compounds scavengers than those doped with Ge. These results also suggest that the presence of silicon and germanium atoms in the CNTs structures enhances their reactivity toward nucleophilic molecules, compared to pristine carbon nanotubes

Fabrication of Eu doped CdO [Al/Eu-nCdO/p-Si/Al] photodiodes by perfume atomizer based spray technique for opto-electronic applications

Science.gov (United States)

Ravikumar, M.; Ganesh, V.; Shkir, Mohd; Chandramohan, R.; Arun Kumar, K. Deva; Valanarasu, S.; Kathalingam, A.; AlFaify, S.

2018-05-01

In this study, thin films of cadmium oxide (CdO) with different concentrations (0, 1, 3, and 5 wt%) of Eu doping were deposited onto Si and glass substrates by a novel and facile spray technique using simple perfume atomizer for the first time. Prepared films were characterized for structural, morphological, optical properties and the photo diode studies, using X-ray diffraction, scanning electron microscope, UV-Vis spectrophotometer, Isbnd V characteristics, and fundamental parameters are reported. All the prepared Eu:CdO films exhibit cubic structure. The preferential orientation is along (200) plane. Scanning electron microscopy study indicates the growth of smooth and pin-hole free films with clusters of homogeneous grains. The values of band gap energy are found to be varying from 2.42 to 2.33 eV for various Eu doping concentration from 0 to 5 wt%. EDAX studies revealed the presence of Eu, Cd and O elements without any other impurities. FTIR spectra showed a peak at 575 cm-1 confirming the stretching mode of Cdsbnd O. The resistivity (ρ), high carrier concentration (n) and carrier mobility (μ) for 3 wt% CdO thin film are found to be 0.452 × 10-3(Ω.cm), 17.82 × 1020 cm-3 and 7.757 cm2/V, respectively. Current-voltage measurements on the fabricated nanostructured Al/Eu-nCdO/p-Si/Al heterojunction device showed a non-linear electric characteristics indicating diode like behaviour.

Effect of Er-doping on the structural and optical properties of Cd{sub 2}V{sub 2}O{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Lozada-Morales, R.; Cid-Garcia, A.; Palomino-Merino, R. [Benemerita Universidad Autonoma de Puebla, Postgrado en Fisica Aplicada, Facultad de Ciencias Fisico-Matematicas, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico); Lopez-Calzada, G.; Jimenez-Sandoval, S. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro, Apartado Postal 1-798, Queretaro, Qro. 76001 (Mexico); Zayas, Ma.E. [Departamento de Investigacion en Fisica de la Universidad de Sonora, Edificio 3I, Blvd. Edificio 5 E, Luis Encinas s/n, Col. Centro, 83000 Hermosillo, Sonora (Mexico); Zelaya-Angel, O. [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados, P.O. Box 14-740, Mexico D. F. 07360 (Mexico); Carmona-Rodriguez, J. [Instituto Tecnologico Superior de Poza Rica, Calle Luis Donaldo Colosio S/N, Col. Arroyo del Maiz, C.P. 93230, Poza Rica, Veracruz (Mexico); Rubio-Rosas, E. [Centro de Vinculacion Universitaria, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico); Portillo-Moreno, O. [Facultad de Ciencias Quimicas, Av. 14, San Claudio, Col. San Manuel, Puebla (Mexico)

2012-11-15

The melt-quenching method was used to prepare two groups of samples using CdO and V{sub 2}O{sub 5} as starting materials. Taking into account that a crystalline-amorphous phase transition would be expected for the CdO-V{sub 2}O{sub 5} system, a first batch was prepared varying the proportions of CdO and V{sub 2}O{sub 5} in the intervals 60-95 and 40-5 wt%, respectively. With the aim of investigating the effect of erbium in the phase transition and crystalline quality of the first group of samples, a second batch was fabricated with the same proportions of CdO and V{sub 2}O{sub 5}, with the addition of 5 wt% of Er(NO{sub 3})5H{sub 2}O as source of Er{sup 3+} ions. It was found that crystalline or amorphous samples could be obtained depending on the relative concentrations of CdO and V{sub 2}O{sub 5}, and that the borderline between amorphous and crystalline samples was affected by the incorporation of Er. From X-ray diffraction, it was possible to identify the formation of the ternary compound Cd{sub 2}V{sub 2}O{sub 7} in the crystalline cases. The Raman and infrared bands in these samples were in agreement with the lattice modes of Cd{sub 2}V{sub 2}O{sub 7}. Additionally, an improvement in the crystalline quality of Cd{sub 2}V{sub 2}O{sub 7} was obtained for the Er-doped samples. The effect of the local environment around the Er{sup 3+} ions on the room temperature photoluminescence was also investigated for the amorphous and crystalline samples. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Enhanced photovoltaic performance of quantum dot-sensitized solar cells with a progressive reduction of recombination using Cu-doped CdS quantum dots

Science.gov (United States)

Muthalif, Mohammed Panthakkal Abdul; Lee, Young-Seok; Sunesh, Chozhidakath Damodharan; Kim, Hee-Je; Choe, Youngson

2017-02-01

In this article, we have systematically probed the effect of Cu-doping in CdS quantum dots (QDs) to enhance the photovoltaic performance of the quantum dot-sensitized solar cells (QDSSCs). The Cu-doped CdS photoanodes were prepared by successive ionic layer adsorption and reaction (SILAR) method and the corresponding cell devices were fabricated using CuS counter electrodes with a polysulfide electrolyte. The photovoltaic performance results demonstrate that 3 mM Cu-doped CdS QDs based QDSSCs exhibit the efficiency (η) of 3% including JSC = 9.40 mA cm-2, VOC = 0.637 V, FF = 0.501, which are higher than those with bare CdS (η = 2.05%, JSC = 7.12 mA cm-2, VOC = 0.588 V, FF = 0.489). The structural, topographical and optical properties of the thin films have been studied with the help of X-ray diffraction pattern (XRD), atomic force microscopy (AFM) and UV-vis spectrophotometer. Electrochemical impedance spectroscopy (EIS) and open circuit voltage decay (OCVD) measurements indicate that Cu-dopant can inhibit the charge recombination at the photoanode/electrolyte interface and extend the lifetime of electrons. These results reveal that incorporation of copper metal in CdS QDs is a simple and effective method to improve the photovoltaic properties of QDSSCs.

Synthesis and study of the magnetic properties of thallium-based over-doped superconducting compounds

International Nuclear Information System (INIS)

Opagiste, C.

1994-07-01

The synthesis, structure and magnetic properties of the normal and superconducting states of over-doped Tl 2 Ba 2 Cu O 6±x and Tl 2 Ba 2 Ca Cu 2 O 8±x superconducting compounds, are presented. Synthesis under high pressure using Tl 2 Ba 2 O 5 as a precursor avoids thallium losses and Ba Cu O 2 formation. The entire over-doped region has been investigated (Tc ranging from 0 to 92 K) and the different stability zones for the two crystallographic structures have been explored. The orthorhombic structure is shown to be stoichiometric in cations, while the tetragonal one could present thallium deficiency. Clear correlations have been established between Tc and the lattice parameters for the two phases. It has been observed that the Meissner fraction increased with Tc and that the reversibility domain was more extended for samples having a Tc near the maximal value, which must be linked to the decrease of the anisotropy with over-doping. In the reversible regime, the mixed state is affected by thermal fluctuations around Tc. Evolution of the penetration depth with Tc is examined; it shows that the optimum doped compound (maximal Tc) behaves as a BCS type superconductor. The over-doping results in a penetration depth behaviour which strongly deviates from the standard model (BCS, two fluids). The zero temperature, obtained by extrapolation, seems to be independent of the over-doping. 54 figs., 3 tabs., 168 refs

Electrochemical Incineration of Phenolic Compounds from the Hydrocarbon Industry Using Boron-Doped Diamond Electrodes

Directory of Open Access Journals (Sweden)

Alejandro Medel

2012-01-01

Full Text Available Electrochemical incineration using boron-doped diamond electrodes was applied to samples obtained from a refinery and compared to the photo-electro-Fenton process in order to selectively eliminate the phenol and phenolic compounds from a complex matrix. Due to the complex chemical composition of the sample, a pretreatment to the sample in order to isolate the phenolic compounds was applied. The effects of the pretreatment and of pH on the degradation of the phenolic compounds were evaluated. The results indicate that the use of a boron-doped diamond electrode in an electrochemical incineration process mineralizes 99.5% of the phenolic sample content. Working in acidic medium (pH = 1, and applying 2 A at 298 K under constant stirring for 2 hours, also results in the incineration of the reaction intermediates reflected by 97% removal of TOC. In contrast, the photo-electro-Fenton process results in 99.9% oxidation of phenolic compounds with only a 25.69% removal of TOC.

Electronic structures and magnetism for carbon doped CdSe: Modified Becke–Johnson density functional calculations

Energy Technology Data Exchange (ETDEWEB)

Fan, S.W., E-mail: fansw1129@126.com; Song, T.; Huang, X.N.; Yang, L.; Ding, L.J.; Pan, L.Q.

2016-09-15

Utilizing the full potential linearized augment plane wave method, the electronic structures and magnetism for carbon doped CdSe are investigated. Calculations show carbon substituting selenium could induce CdSe to be a diluted magnetic semiconductor. Single carbon dopant could induce 2.00 μ{sub B} magnetic moment. Electronic structures show the long-range ferromagnetic coupling mainly originates from the p–d exchange-like p–p coupling interaction. Positive chemical pair interactions indicate carbon dopants would form homogeneous distribution in CdSe host. The formation energy implies the non-equilibrium fabricated technology is necessary during the samples fabricated. - Highlights: • The C{sub Se} defects could induce the CdSe to be typical diluted magnetic semiconductor. • Electronic structures show ferromagnetism come from p-d exchange-like p-p coupling. • Chemical pair interactions indicate C{sub Se} prefer homogenous distribution in CdSe host.

Synthesis, characterizations and anti-bacterial activities of pure and Ag doped CdO nanoparticles by chemical precipitation method.

Science.gov (United States)

Sivakumar, S; Venkatesan, A; Soundhirarajan, P; Khatiwada, Chandra Prasad

2015-02-05

In the present study, synthesized pure and Ag (1%, 2%, and 3%) doped Cadmium Oxide (CdO) nanoparticles by chemical precipitation method. Then, the synthesized products were characterized by thermo gravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy, Ultra violet-Vis diffused reflectance spectroscopy (UV-Vis-DRS), Scanning electron microscopy (SEM), Energy dispersive X-rays (EDX) spectroscopy, and anti-bacterial activities, respectively. The transition temperatures and phase transitions of Cd(OH)2 to CdO at 400°C was confirmed by TG-DTA analysis. The XRD patterns show the cubic shape and average particle sizes are 21, 40, 34, and 37nm, respectively for pure and Ag doped samples. FT-IR study confirmed the presence of CdO and Ag at 677 and 459cm(-1), respectively. UV-Vis-DRS study shows the variation on direct and indirect band gaps. The surface morphologies and elemental analysis have been confirmed from SEM and with EDX. In addition, the synthesized products have been characterized by antibacterial activities against Gram-positive and negative bacteria. Further, the present investigation suggests that CdO nanoparticles have the great potential applications on various industrial and medical fields of research. Copyright © 2014 Elsevier B.V. All rights reserved.

Efficient n-type doping of CdTe epitaxial layers grown by photo-assisted molecular beam epitaxy with the use of chlorine

Energy Technology Data Exchange (ETDEWEB)

Hommel, D.; Scholl, S.; Kuhn, T.A.; Ossau, W.; Waag, A.; Landwehr, G. (Univ. Wuerzburg, Physikalisches Inst. (Germany)); Bilger, G. (Univ. Stuttgart, Inst. fuer Physikalische Elektronik (Germany))

1993-01-30

Chlorine has been used successfully for the first time for n-type doping of CdTe epitaxial layers (epilayers) grown by photo-assisted molecular beam epitaxy. Similar to n-type doping of ZnSe layers, ZnCl[sub 2] has been used as source material. The free-carrier concentration can be varied over more than three orders of magnitude by changing the ZnCl[sub 2] oven temperature. Peak mobilities are 4700 cm[sup 2] V[sup -1] s[sup -1] for an electron concentration of 2x10[sup 16] cm[sup -3] and 525 cm[sup 2] V[sup -1] s[sup -1] for 2x10[sup 18] cm[sup -3]. The electrical transport data obtained by Van der Pauw configuration and Hall structure measurements are consistent with each other, indicating a good uniformity of the epilayers. In photoluminescence the donor-bound-exciton emission dominates for all chlorine concentrations. This contasts significantly with results obtained for indium doping, commonly used for obtaining n-type CdTe epilayers. The superiority of chlorine over indium doping and the influence of growth parameters on the behaviour of CdTe:Cl layers will be discussed on the basis of transport, luminescence, secondary ion mass spectroscopy and X-ray photoelectron spectroscopy data. (orig.).

Synthesis and Thermoelectric Properties of Ni-Doped ZrCoSb Half-Heusler Compounds

Directory of Open Access Journals (Sweden)

Degang Zhao

2018-01-01

Full Text Available The Ni-doped ZrCo1−xNixSb half-Heusler compounds were prepared by arc-melting and spark plasma sintering technology. X-ray diffraction analysis results showed that all samples were crystallized in a half-Heusler phase. Thermoelectric properties of ZrCo1−xNixSb compounds were measured from room temperature to 850 K. The electrical conductivity and the absolute value of Seebeck coefficient increased with the Ni-doping content increasing due to the Ni substitution at Co. sites. The lattice thermal conductivity of ZrCo1−xNixSb samples was depressed dramatically because of the acoustic phonon scattering and point defect scattering. The figure of merit of ZrCo1−xNixSb compounds was improved due to the decreased thermal conductivity and improved power factor. The maximum ZT value of 0.24 was achieved for ZrCo0.92Ni0.08Sb sample at 850 K.

Synthesis and characterization of Sn-doped CdZnS nanoparticles

Indian Academy of Sciences (India)

Administrator

Average crystallite size was measured from XRD data by using Scherrer's ... the solar cell.9 This CdZnS ternary compound is also potentially useful as a ... a monochromatic CuKα radiation (λ = 1.540600 Å) and an aperture diaphragm of 0.2°, ...

Local polarization phenomena in In-doped CdTe x-ray detector arrays

International Nuclear Information System (INIS)

Sato, Toshiyuki; Sato, Kenji; Ishida, Shinichiro; Kiri, Motosada; Hirooka, Megumi; Yamada, Masayoshi; Kanamori, Hitoshi

1995-01-01

Local polarization phenomena have been studied in detector arrays with the detector element size of 500 microm x 500 microm, which are fabricated from high-resistivity In-doped CdTe crystals grown by the vertical Bridgman technique. It has been found for the first time that a polarization effect, which is characterized by a progressive decrease of the pulse counting rate with increasing photon fluence, strongly depends on the detector elements, that is, the portion of crystals used. The influence of several parameters, such as the applied electric field strength, time, and temperature, on this local polarization effect is also investigated. From the photoluminescence measurements of the inhomogeneity of In dopant, it is concluded that the local polarization effect observed here originates from a deep level associated with In dopant in CdTe crystals

Well-resolved oil-soluble Au-doped ZnCdS quantum dots and enhancing doping emission with In-codoping

Energy Technology Data Exchange (ETDEWEB)

Zeng, Ruosheng, E-mail: zengrsh@gznu.edu.cn [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China); School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001 (China); Sun, Zhiguo [School of Chemistry and Materials Science, Guizhou Normal University, Guiyang 550001 (China); Zhou, Chunjiao [College of Science, Hunan Agricultural University, Changsha 410128 (China); Fang, Cheng; Han, Guo-Cheng [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China); Chen, Zhencheng, E-mail: chenzhcheng@guet.edu.cn [School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004 (China)

2016-06-25

Highly emissive semiconductor quantum dots (QDs) with tunable color are valuable in many applications such as solid state lighting and bio-imaging. Herein, we report a facile synthetic method to Au:ZnCdS and Au:ZnCdS/ZnS core/shell QDs with tunable emission color. The highly active Au precursor (HAuCl{sub 4}) is prevented to be decomposed at high reaction temperature using 1-dodecanethiol (DDT) as the surface ligand. High-quality Au:ZnCdS/ZnS core/shell QDs are prepared and the highest photoluminescence (PL) quantum yield (QY) can achieve 42% by overcoating of ZnS layer over the bare Au:ZnCdS core QDs. Furthermore, through using Au{sup +} ion as the primary dopants and trivalent cation In{sup 3+} as co-dopants, the PL QY can be enhanced significantly because compensation of In{sup 3+} ion-codoping for the charge imbalance from Au{sup +}-doping. This codoping strategy may be applied to other related optical materials to control the optical properties based on our understanding for physical mechanism. - Highlights: • High-quality oil-soluble Au:ZnCdS/ZnS QDs were prepared for the first time. • The highly active HAuCl4 is prevented to decompose by using 1-dodecanethiol. • The highest PL QY of Au:ZnCdS/ZnS QDs can achieve 42% by overcoating ZnS layer. • The PL QY of QDs can be significantly enhanced by Au{sup +}, In{sup 3+}-codoping.

Effect of Cd doping on magnetocaloric effect and critical behavior analysis on perovskite Nd1-xCdxMnO3 (x = 0, 0.1, 0.2, 0.3, and 0.4) manganite polycrystals

Science.gov (United States)

Saravanan, C.; Thiyagarajan, R.; Manikandan, K.; Sathiskumar, M.; Kanjariya, P. V.; Bhalodia, J. A.; Arumugam, S.

2017-12-01

We report the doping effect of divalent cation Cd2+ at Nd-site of intermediate bandwidth manganite system NdMnO3 through the temperature- and magnetic field-dependent magnetization measurements. The parent compound shows paramagnetic-antiferromagnetic transition at 56 K, whereas Cd doped samples show the paramagnetic-ferromagnetic transition with fluctuating TC. During this transition, Nd1-xCdxMnO3 (x = 0.1 and 0.2) samples exhibit first order nature, whereas Nd1-xCdxMnO3 (x = 0.3 and 0.4) samples exhibit second order nature. It confirms a crossover from first order transition to second order transition while x = 0.2 to x = 0.3. By having first order transition, x = 0.2 sample exhibits high magnetic entropy change of 3.62 J kg-1 K-1 for the magnetic field change of 5 T out of all compositions. By having second order transitions, x = 0.4 sample exhibits a high relative cooling power of 319.71 J kg-1 for the magnetic field change of 5 T out of all the compositions. The critical behavior of second order transition of x = 0.3 and 0.4 samples has been analyzed using Arrott and Kouvel-Fisher plots. The estimated critical exponents of these samples are nearly matched with the mean free model, which can be explained by the existence of dipole-dipole interaction by the Cd doping which strengthens long range ferromagnetic interactions between the spins.

Optical and electrical properties of In-doped CdO thin films fabricated by pulse laser deposition

International Nuclear Information System (INIS)

Zheng, B.J.; Lian, J.S.; Zhao, L.; Jiang, Q.

2010-01-01

Transparent indium-doped cadmium oxide (In-CdO) thin films were deposited on quartz glass substrates by pulse laser deposition (PLD) from ablating Cd-In metallic target at a fixed pressure 10 Pa and a fixed substrate temperature 300 deg. C. The influences of indium concentrations in target on the microstructure, optical and electrical performances were studied. When the indium concentration reaches to 3.9 wt%, the as-deposited In-CdO film shows high optical transmission in visible light region, obviously enhanced direct band gap energy (2.97 eV), higher carrier concentration and lower electric resistivity compared with the undoped CdO film, while a further increase of indium concentration to 5.6 wt% induces the formation of In 2 O 3 , which reverse the variation of these parameters and performance.

Mesoporous nitrogen-doped carbon microfibers derived from Mg-biquinoline-dicarboxy compound for efficient oxygen electroreduction

Energy Technology Data Exchange (ETDEWEB)

Kong, Aiguo, E-mail: agkong@chem.ecnu.edu.cn [School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241 (China); Fan, Xiaohong; Chen, Aoling [School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241 (China); Zhang, Hengiang [School of Chemistry and Chemical Engineering, Hebei Normal University for Nationalities, Chengde 067000 (China); Shan, Yongkui, E-mail: agkong@chem.ecnu.edu.cn [School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241 (China)

2017-02-15

An in-situ MgO-templating synthesis route was introduced to obtain the mesoporous nitrogen-doped carbon microfibers by thermal conversion of new Mg-2,2′-biquinoline 4,4-dicarboxy acid coordination compound (Mg-DCA) microfibers. The investigated crystal structure of Mg-DCA testified that the assembling of Mg{sup 2+} and DCA through Mg-O coordination bond and hydrogen bond contributed to the formation of one-dimensional (1D) crystalline Mg-DCA microfibers. The nitrogen-doped carbons derived from the pyrolysis of Mg-DCA showed the well-defined microfiber morphology with high mesopore-surface area. Such mesoporous microfibers exhibited the efficient catalytic activity for oxygen reduction reaction (ORR) in alkaline solutions with better stability and methanol-tolerance performance. - Graphical abstract: Mesoporous nitrogen-doped carbon microfibers with efficient oxygen electroreduction activity were prepared by thermal conversion of new Mg-biquinoline-based coordination compound microfibers.

Molecular dinamics of tetrahedral clelate compounds of Cd(2) in solutions

International Nuclear Information System (INIS)

Nivorozhkin, L.E.; Minkin, V.I.; Borisenko, N.I.; Konstantinovskij, L.E.; Korobov, M.S.; Olekhnovich, R.Ya.

1981-01-01

Interconversion kinetics of enantiomers of tetrahedral intracomplex compounds of metals (ICM) on the base of unsymmetric ligands in solu-- tions is studied for several series of compounds according to the temperature dependence of the shape of line of prochiral substituents using the methods of the dynamic NMR (DNMR). The use of tetracoordinated ICM in the solutions of synthesized compounds of Cd(2) with the inclusion of magnetic isotope 111 Cd(S=1/2) to study molecular dynamics and the application of the corresponding methods of calculation of the DNMR signal forms permitted to clearly separate the mechanisms of digonal twist and degenerated ligand exchange. In ICM solutions the low-barrier transformations, connected with intramolecular digonal twist, take place as well as high-barrier processes of degenerated ligand exchange. The technique suggested can be applied to the studies of ICM molecular dynamics with other magnetic isotopes of metals ( 207 Pb, 199 Hg, etc.) and rapid non-degenerated ligand exchanges [ru

Influence of Al doping on optical properties of CdS/PVA nanocomposites: Theory and experiment

Energy Technology Data Exchange (ETDEWEB)

Bala, Vaneeta, E-mail: vaneetabala@yahoo.com; Tripathi, S. K., E-mail: vaneetabala@yahoo.com; Kumar, Ranjan, E-mail: vaneetabala@yahoo.com [Department of Physics, Panjab University, Chandigarh (India)

2014-04-24

In the present work theoretical and experimental studies of aluminium doped cadmium sulphide polyvinyl alcohol (Al:CdS/PVA) nanocomposites have been carried out. Tetrahedral cluster AlCd{sub 9}S{sub 2}(SH){sub 18}]{sup 1−} has been encapsulated by small segments of polyvinyl alcohol (PVA) chains in order to simulate experimental environment of nanocomposites. Density functional theory (DFT) using local density approximation (LDA) functionals is employed to study the broadening of band gap upon ligation of nanoclusters. We have used in situ chemical route to synthesize nanocomposites. Optical band gap has been calculated from both experimental and theoretical approach.

Nanocauliflower like structure of CdS thin film for solar cell photovoltaic applications: Insitu tin doping by chemical bath deposition technique

CSIR Research Space (South Africa)

Wilson, KC

2014-01-01

Full Text Available ). The Sn(sup4+) doping markedly influenced on the evolution of the CdS nanostructures, resulting in the formation of nanocracks due to the substitution of Cd(sup2+) ions by larger-than-host Sn(sup4+) ions as well as a drastic increase in electrical...

Structural and optical properties of Ni-doped CdS thin films prepared by chemical bath deposition method

Energy Technology Data Exchange (ETDEWEB)

Premarani, R. [Arumugam Pillai SeethaiAmmal College, Thiruppattur-630211 (India); Saravanakumar, S., E-mail: sarophy84@gmail.com; Chandramohan, R. [SreeSevuganAnnamalai College, Devakottai-630303 (India); Mahalingam, T. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of)

2015-06-24

The structural and optical behavior of undoped Cadmiun Sulphide (CdS) and Ni-doped CdS thinfilms prepared by Chemical Bath Deposition (CBD) technique is reported. The crystallite sizes of the thinfilms have been characterized by X-ray diffraction pattern (XRD). The particle sizes increase with the increase of Ni content in the CdS thinfilms. Scanning Electron Microscope (SEM) results indicated that CdS thinfilms is made up of aggregate of spherical-like particles. The composition was estimated by Energy Dispersive Analysis of X-ray (EDX) and reported. Spectroscopic studies revealed considerable improvement in transmission and the band gap of the films changes with addition of Ni dopant that is associated with variation in crystallite sizes in the nano regime.

Cationic surfactant assisted ultrasound synthesis of Dy3+ doped CdSiO3 nanostructures for white LED application

Science.gov (United States)

Basavaraj, R. B.; Nagabhushana, H.; Lingaraju, K.; Prasad, B. Daruka

2017-05-01

In this paper we report for the first time Dy3+ (1-7 mol %) doped CdSiO3 nanophosphors prepared via facile ultrasound supported sonochemical route using EGCG (epigallocatechin gallate). The final product was well characterized by PXRD, FTIR, SEM, TEM and PL. The powder X-ray diffraction (PXRD) profiles showed monoclinic phase with highly crystalline nature. The sonication time, concentration of the surfactant play vital role in tuning the morphology. The crystallite size was calculated from PXRD patterns as well as by TEM image and it was found to 20-30 nm. The Fourier transform infrared spectroscopy (FTIR) results confirmed the presence of Si-O-Si and Si-O stretching vibrations in CdSiO3. Photoluminescence properties of Dy3+ (1-7 mol %) doped CdSiO3 excited under near ultra violet wavelength (350 nm) was studied in order to investigate the possibility of its use in white light emitting diode applications. The emission spectra consists of intra 4f transitions of Dy3+, namely 4F9/2 → 6H15/2 (480 nm), and 4F9/2 → 6H13/2 (574 nm) respectively. The 3 mol% Dy3+ doped phosphor showed maximum intensity. The Commission Internationale de I'Eclairage (CIE) and correlated color temperature (CCT) was evaluated. Further, the quantum efficiency and color purity results of the product showed high efficiency and it was highly useful in white light emitting diodes (wLEDs) applications.

Spectroscopy of deep doping levels in Cd0.99Mn0.01Te:Ga

International Nuclear Information System (INIS)

Szatkowski, J.; Placzek-Popko, E.; Sieranski, K.; Bieg, B.

1997-01-01

The investigation results of deep energy levels in Cd 0.99 Mn 0.01 Te (n-type) doped with gallium have been presented. Deep level transient spectroscopy (DLTS) measurements have been carried out in temperature range 80-420 K. The results show five types of electron traps. The activation energy of trapping levels and electron trapping cross-sections have been determined for observed traps. 2 refs, 3 figs, 1 tab

Anodic stripping voltammetry of synthesized CdS nanoparticles at boron-doped diamond electrodes

Energy Technology Data Exchange (ETDEWEB)

Hayat, Mohammad; Ivandini, Tribidasari A., E-mail: ivandini.tri@sci.ui.ac.id; Saepudin, Endang [Department of Chemistry, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Einaga, Yasuaki [Department of Chemistry, Keio University (Japan)

2016-04-19

Cadmium sulphide (CdS) nanoparticles were chemically synthesized using reverse micelles microreactor methods. By using different washing treatments, UV-Vis spectroscopy showed that the absorption peaks appeared at 465 nm, 462 nm, 460 nm, and 459 nm respectively for CdS nanoparticles without and with 1, 2, and 3 times washing treatments using pure water. In comparison with the absorbance peak of bulk CdS at 512 nm, the shifted absorption peaks, indicates that the different sizes of CdS can be prepared. Anodic stripping voltammetry of the CdS nanoparticles was then studied at a boron-doped diamond electrode using 0.1 M KClO{sub 4} and 0.1 M HClO{sub 4} as the electrolytes. A scan rate of 100 mV/s with a deposition potential of -1000 mV (vs. Ag/AgCl) for 60 s at a potential scan from -1600 mV to +800 mV (vs. Ag/AgCl) was applied as the optimum condition of the measurements. Highly-accurate linear calibration curves (R{sup 2} = 0.99) in 0.1 M HClO{sub 4} with the sensitivity of 0.075 mA/mM and the limit of detection of 81 µM in 0.1 M HClO{sub 4} can be achieved, which is promising for an application of CdS nanoparticles as a label for biosensors.

Evolution of ground-state wave function in CeCoIn5 upon Cd or Sn doping

Science.gov (United States)

Chen, K.; Strigari, F.; Sundermann, M.; Hu, Z.; Fisk, Z.; Bauer, E. D.; Rosa, P. F. S.; Sarrao, J. L.; Thompson, J. D.; Herrero-Martin, J.; Pellegrin, E.; Betto, D.; Kummer, K.; Tanaka, A.; Wirth, S.; Severing, A.

2018-01-01

We present linear polarization-dependent soft-x-ray absorption spectroscopy data at the Ce M4 ,5 edges of Cd- and Sn-doped CeCoIn5. The 4 f ground-state wave functions have been determined for their superconducting, antiferromagnetic, and paramagnetic ground states. The absence of changes in the wave functions in CeCo (In1-xCdx) 5 suggests that the 4 f -conduction-electron (c f ) hybridization is not affected by global Cd doping, thus supporting the interpretation of magnetic droplets nucleating long-range magnetic order. This is contrasted by changes in the wave function due to Sn substitution. Increasing Sn in CeCo (In1-ySny) 5 compresses the 4 f orbitals into the tetragonal plane of these materials, suggesting enhanced c f hybridization with the in-plane In(1) atoms and a homogeneous altering of the electronic structure. As these experiments show, the 4 f wave functions are a very sensitive probe of small changes in the hybridization of 4 f and conduction electrons, even conveying information about direction dependencies.

Cd(II) and Zn(II) thiocyanate coordination compounds with 3-ethylpyridine. Synthesis, crystal structures and properties

Energy Technology Data Exchange (ETDEWEB)

Neumann, Tristan; Jess, Inke; Dos Santos Cunha, Cesar; Terraschke, Huayna; Naether, Christian [Kiel Univ. (Germany). Inst. fuer Anorganische Chemie

2018-04-01

Reaction of Cd(NCS){sub 2} and Zn(NCS){sub 2} with 3-ethylpyridine leads to the formation of compounds of compositions M(NCS){sub 2}(3-ethylpyridine){sub 4} (M=Cd, 1-Cd; Zn, 1-Zn) and M(NCS){sub 2}(3-ethylpyridine){sub 2} (M=Cd, 2-Cd; Zn, 2-Zn). 1-Cd and 1-Zn are isotypic and form discrete complexes in which the metal cations are octahedrally coordinated by two trans-coordinating N-bonded thiocyanate anions and four 3-ethylpyridine co-ligands. In 2-Cd the cations are also octahedrally coordinated but linked into chains by pairs of μ-1,3-bridging anionic ligands. 2-Zn is built up of discrete complexes, in which the Zn cation is tetrahedrally coordinated by two N-bonded thiocyanate anions and two 3-ethylpyridine co-ligands. Compounds 1-Cd, 2-Cd and 2-Zn can be prepared in a pure state, whereas 1-Zn is unstable and transforms on storage into 2-Zn. If 1-Cd and 1-Zn are heated, a transformation into 2-Cd, respectively 2-Zn is observed. Luminescence measurements reveal that 1-Cd, 2-Cd and 2-Zn emit light in the blue spectral range with maxima at, respectively, 21724, 21654 and 22055 cm{sup -1}, assigned to ligand-based luminescence.

Effect of Al doping on structural and mechanical properties of Ni-Cd ferrites

Science.gov (United States)

Shidaganal, Lata C.; Gandhad, Sheela S.; Hiremath, C. S.; Mathad, S. N.; Jeergal, P. R.; Pujar, R. B.

2018-05-01

Ferrites are ceramic magnetic materials which behave like a conventional ferromagnetic. Ni-Zn ferrites are commercially used as electromagnetic interfaces in hard disc drives, laptops and other electronic devices. Here we are going to report on the structural and mechanical properties of Al doped Ni-Cd ferrites synthesized by standard double sintering ceramic method by using AR grade Al oxide, Ni oxide, Cd oxide and ferric oxide in molar proportions with a general chemical formula Ni0.5 Cd0.5 Alx Fe2-x O4 where x=0.1 to 0.4.X-ray analysis confirms the formation of single phase FCC spinel structure. The decrease in lattice constant with Al concentration is attributed to Vegard's law. IR spectra indicate prominent absorption bands near 400cm-1and 600cm-1 which are assigned to fundamental vibrations of complexes in A and B sites respectively. SEM micrographs exhibit fine grains without segregation of impurities. The average grain diameter is found vary from 1.00µm to 0.9 µm which is in agreement with Vegard's law.

Observation of local fields in ZnO using the 111Cd probe

International Nuclear Information System (INIS)

Sato, W.; Komatsuda, S.; Imagawa, E.; Ohkubo, Y.; Yamada, Y.

2011-01-01

The authors prepared the ZnO sample ( 111m Cd-CZO) that contains totally 0.5 at.% of Cd including 111m Cd, and the ZnO sample ( 111m Cd-ICZO) made by doping with 0.5 at.% of In to 111m Cd-CZO, and measured γ-ray perturbed angular correlation (PAC) spectra. They compared these measurement results with the PAC spectra that were observed in the sample ( 111 In-IZO) made by doping with 0.5 at.% of stable In isotope in addition to ( 111 In→) 111 Cd probe, and examined the two characteristics of 111 In-IZO. As for 111 In-IZO, large electric field gradient and late effect due to remarkable EC decay was observed compared with the sample ( 111 In-UZO), where several ppt level of ( 111 In→) 111 Cd probe was solely doped into ZnO. This fact suggests that In atoms and 111 In atoms flocculate locally. When this flocculating condition is made of many In atom groups, several occupation positions of 111 In can be considered, and they cannot form the single frequency component as obtained in the PAC spectra. Therefore, the results of this experiment can be understood that In atoms themselves form the pairs in the nearest position while replacing the lattice positions of Zn. In is generally stable under the condition of three valence, but it can take one valence depending on compounds. Therefore, it can be considered that if In 3+ and In + mixture in this ratio replace Zn 2+ sites, this pairs can exist from the viewpoint of charge balance. (A.O.)

Highly conducting and transparent Ti-doped CdO films by pulsed laser deposition

International Nuclear Information System (INIS)

Gupta, R.K.; Ghosh, K.; Patel, R.; Kahol, P.K.

2009-01-01

Titanium-doped cadmium oxide thin films were deposited on quartz substrate by pulsed laser deposition technique. The effect of substrate temperature on structural, optical and electrical properties was studied. The films grown at high temperature show (2 0 0) preferred orientation, while films grown at low temperature have both (1 1 1) and (2 0 0) orientation. These films are highly transparent (63-79%) in visible region, and transmittance of the films depends on growth temperature. The band gap of the films varies from 2.70 eV to 2.84 eV for various temperatures. It is observed that resistivity increases with growth temperature after attaining minimum at 150 deg. C, while carrier concentration continuously decreases with temperature. The low resistivity, high transmittance and wide band gap titanium-doped CdO films could be an excellent candidate for future optoelectronic and photovoltaic applications.

Structural, optical and electrical characterization of Mn2+ and Cd2+ doped/co-doped PbS nanocrystals

International Nuclear Information System (INIS)

Sakthi Sudar Saravanan, R.; Meena, M.; Pukazhselvan, D.; Mahadevan, C.K.

2015-01-01

Highlights: • Mn and Cd doped/codoped nano PbS was synthesized by SMI method. • The observed stress is ∼90% lower, and the strain is only in the order of 10 −6 . • Band gap value can be enhanced from 0.5 eV to 2.025–2.235 eV (±0.012 eV). • Role of two conduction activation barriers was observed. - Abstract: The strain and stress minimized nanoparticles of PbS, Pb 0.95 Mn 0.05 S, Pb 0.95 Cd 0.05 S and Pb 0.90 Mn 0.05 Cd 0.05 S were successfully synthesized using solvothermal microwave irradiation (SMI) method. The quality/performance of the materials was found to be in the series Pb 0.90 Mn 0.05 Cd 0.05 S > Pb 0.95 Cd 0.05 S > Pb 0.95 Mn 0.05 S > PbS. The average crystallite size in the best material Pb 0.90 Mn 0.05 Cd 0.05 S was found to be ∼18 nm where the particles are distributed within the range 20–60 nm. Optical studies reveals the existence of direct band gap in the range of 2.025–2.235 eV (±0.012 eV). This is one of the widest E g values reported for this system. Electrical measurements were performed on compacts of nanoparticles in the temperature range 313–433 K and frequency range 100 Hz–1 MHz. The conductivity profile exhibits two components; in which the activation energy (ΔE) values obtained for the temperature range 373–433 K is almost twice as compared to the ΔE value obtained for 313–373 K. Nonetheless, the conductivity at the higher temperatures was always higher than at the low temperatures and interestingly, the nanoparticles exhibits higher conductivity than their bulk counterpart. The feasible mechanism of conduction is discussed

Application of glass particles doped by Zn+2 as an antimicrobial and atoxic compound in LLDPE and HDPE

International Nuclear Information System (INIS)

Santos, M.F.; Machado, C.; Tachinski, C.G.; Júnior, J.F.; Piletti, R.; Peterson, M.; Fiori, M.A.

2014-01-01

This study demonstrates the potential application of glass particles doped with Zn +2 (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0 ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00 wt.% and at a time of 4 h, the bactericidal performance is excellent and equal for both polymeric compounds. - Highlights: • Glass doped with Zn +2 (GZn) promoted a good bactericidal properties in LLDPE and HDPE. • LLDPE and HDPE doped with GZn have capacity of liberty ionic zinc during a time period. • GZn is not toxic to human and can be used with antimicrobial additive to polymers. • GZn has an antimicrobial effect in bacteria type Gram positive and Gram negative

Antimicrobial activity and second harmonic studies on organic non-centrosymmetric pure and doped ninhydrin single crystals

Science.gov (United States)

Prasanyaa, T.; Jayaramakrishnan, V.; Haris, M.

2013-03-01

In this paper, we report the successful growth of pure, Cu2+ ions and Cd2+ ions doped on ninhydrin single crystals by slow solvent evaporation technique. The presence of Cu2+ and Cd2+ ions in the specimen of ninhydrin single crystal has been determined by atomic absorption spectroscopy. The powder X-ray diffraction analysis was done to calculate the lattice parameters of the pure and doped crystals. The percentage of transmittance of the crystal was recorded using the UV-Vis Spectrophotometer. Thermal behaviors of the grown crystals have been examined by the thermal gravimetric/differential thermal analysis. The hardness of the grown crystals was assessed and the results show the minor variation in the hardness value for the pure and doped ninhydrin samples. The value of the work hardening coefficient n was found to be 2.0, 1.0 and 1.06 for pure, copper and cadmium doped ninhydrin crystals respectively. The second harmonic generation efficiency of Cd2+ and Cu2+ doped ninhydrin is 8.3 and 6.3 times greater than well known nonlinear crystal of potassium dihydrogen phosphate respectively. The antibacterial and antifungal activities of the title compound were performed by disk diffusion method against the standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillis niger and Aspergillus flavus.

Diverse Cd(II) compounds based on N-benzoyl-L-glutamic acid and N-donor ligands: Structures and photoluminescent properties

Science.gov (United States)

Ma, Ning; Guo, Wei-Ying; Song, Hui-Hua; Yu, Hai-Tao

2016-01-01

Five new Cd(II) coordination polymers with N-benzoyl-L-glutamic acid (H2bzgluO) and different N-donor ligands, [Cd(bzgluO)(2,2‧-bipy)(H2O)]n (1), [Cd(bzgluO)(2,4‧-bipy)2(H2O)·3H2O]n (2), [Cd(bzgluO)(phen)·H2O]n (3), [Cd(bzgluO)(4,4‧-bipy)(H2O)]n (4), [Cd(bzgluO)(bpp)(H2O)·2H2O]n (5) were synthesized (2,2‧-bipy=2,2‧-bipyridine, 2,4‧-bipy=2,4‧-bipyridine, phen=1,10-phenanthroline, 4,4‧-bipy=4,4‧-bipyridine, bpp=1,3-di(4-pyridyl)propane). Compounds 1-2 exhibit a 1D single-chain structure. Compound 1 generates a 2D supramolecular structure via π-π stacking and hydrogen bonding, 3D architecture of compound 2 is formed by hydrogen bonding. Compound 3 features a 1D double-chain structure, which are linked by π-π interactions into a 2D supramolecular layer. Compounds 4-5 display a 2D network structure. Neighboring layers of 4 are extended into a 3D supramolecular architecture through hydrogen bonding. The structural diversity of these compounds is attributed to the effect of ancillary N-donor ligands and coordination modes of H2bzgluO. Luminescent properties of 1-5 were studied at room temperature. Circular dichroism of compounds 1, 2 and 5 were investigated.

AgCl-doped CdSe quantum dots with near-IR photoluminescence.

Science.gov (United States)

Kotin, Pavel Aleksandrovich; Bubenov, Sergey Sergeevich; Mordvinova, Natalia Evgenievna; Dorofeev, Sergey Gennadievich

2017-01-01

We report the synthesis of colloidal CdSe quantum dots doped with a novel Ag precursor: AgCl. The addition of AgCl causes dramatic changes in the morphology of synthesized nanocrystals from spherical nanoparticles to tetrapods and finally to large ellipsoidal nanoparticles. Ellipsoidal nanoparticles possess an intensive near-IR photoluminescence ranging up to 0.9 eV (ca. 1400 nm). In this article, we explain the reasons for the formation of the ellipsoidal nanoparticles as well as the peculiarities of the process. The structure, Ag content, and optical properties of quantum dots are also investigated. The optimal conditions for maximizing both the reaction yield and IR photoluminescence quantum yield are found.

Solvothermal synthesis of nanorods of ZnO, N-doped ZnO and CdO

International Nuclear Information System (INIS)

Varghese, Neenu; Panchakarla, L.S.; Hanapi, M.; Govindaraj, A.; Rao, C.N.R.

2007-01-01

ZnO nanorods with diameters in the 80-800 nm range are readily synthesized by the reaction of zinc acetate, ethanol and ethylenediamine under solvothermal conditions. The best products are obtained at 330 deg. C with a slow heating rate. Addition of the surfactant Triton -X 100 gave nanorods of uniform (300 nm) diameter. By adding a small amount of liquid NH 3 to the reaction mixture, N-doped ZnO nanorods, with distinct spectroscopic features are obtained. CdO nanorods of 80 nm diameter have been prepared under solvothermal conditions using a mixture of cadmium cupferronate, ethylenediamine and ethanol at 330 deg. C. Similarly, Zn 1-x Cd x O nanorods of a 70 nm diameter are obtained under solvothermal conditions starting with a mixture of zinc acetate, cadmium cupferronate, ethanol and ethylenediamine

Electrical properties from photoinduced charging on Cd-doped (100) surfaces of CuInSe{sub 2} epitaxial thin films

Energy Technology Data Exchange (ETDEWEB)

Johnson, Nicole, E-mail: nejhnsn2@illinois.edu; Rockett, Angus [Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W Green St., Urbana, Illinois 61801 (United States); Aydogan, Pinar; Suzer, Sefik [Department of Chemistry, Bilkent University, 06800 Ankara (Turkey)

2016-05-15

The photoresponse of Cd-doped CuInSe{sub 2} (CIS) epitaxial thin films on GaAs(100) was studied using x-ray photoelectron spectroscopy under illumination from a 532 nm laser between sample temperatures of 28–260 °C. The initial, air-exposed surface shows little to no photoresponse in the photoelectron binding energies, the Auger electron kinetic energies or peak shapes. Heating between 50 and 130 °C in the analysis chamber results in enhanced n-type doping at the surface and an increased light-induced binding energy shift, the magnitude of which persists when the samples are cooled to room temperature from 130 °C but which disappears when cooling from 260 °C. Extra negative charge trapped on the Cu and Se atoms indicates deep trap states that dissociate after cooling from 260 °C. Analysis of the Cd modified Auger parameter under illumination gives experimental verification of electron charging on Cd atoms thought to be shallow donors in CIS. The electron charging under illumination disappears at 130 °C but occurs again when the sample is cooled to room temperature.

Diffusion and influence of Cu on properties of CdTe thin films and CdTe/CdS cells

Energy Technology Data Exchange (ETDEWEB)

Dzhafarov, T.D.; Yesilkaya, S.S.; Yilmaz Canli, N.; Caliskan, M. [Department of Physics, Yildiz Technical University, Davutpasa, 34210 Istanbul (Turkey)

2005-01-31

The effective diffusion coefficients of Cu for thermal and photodiffusion in the CdTe films have been estimated from resistivity versus duration of thermal or photoannealing curves. In the temperature range 60-200{sup o}C the effective coefficient of thermal diffusion (D{sub t}) and photodiffusion (D{sub ph}) are described as D{sub t}=7.3x10{sup -7}exp(-0.33/kT) and D{sub ph}=4.7x10{sup -8}exp(-0.20/kT). It is found that the diffusion doping of CdTe thin films by Cu at 400{sup o}C results in a sharp decrease of resistivity up to 7 orders of magnitude of p-type material, depending on thickness of Cu film. The comparative study of performance of CdTe(Cu)/CdS and CdTe/CdS cells has been studied. It is shown that the diffusion doping of CdTe film by Cu increases efficiency of CdTe(Cu)/CdS cells from 0.9% to 6.8%. The degradation of photovoltaic parameters of CdTe(Cu)/CdS cell, during testing under forward and reverse bias at room temperature, proceeds at a larger rate than those of CdTe/CdS cell without Cu. The degradation of performance of CdTe(Cu)/CdS cells is tentatively assigned to electrodiffusion of Cu in CdTe, resulting in redistribution of concentration of Cu-related centers in CdTe film and heterojunction region.

Nitrogen-doped titanium dioxide photocatalysts for visible response prepared by using organic compounds

Directory of Open Access Journals (Sweden)

Yoshio Nosaka, Masami Matsushita, Junichi Nishino and Atsuko Y. Nosaka

2005-01-01

Full Text Available In order to utilize visible light in photocatalytic reactions, nitrogen atoms were doped in commercially available photocatalytic TiO2 powders by using an organic compound such as urea and guanidine. Analysis by X-ray photoelectron spectroscopy (XPS indicated that N atoms were incorporated into two different sites of the bulk phase of TiO2. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. These N-doped TiO2 powders exhibited photocatalytic activity for the decomposition of 2-propanol in aqueous solution under visible light irradiation. The photocatalytic activity increased with the decrease of doped N atoms in O site, while decreased with decrease of the other sites. Degradation of photocatalytic activity based on the release of nitrogen atoms was observed for the reaction in the aqueous suspension system.

Evolution of electronic structure in highly charge doped MoS2 compounds

Science.gov (United States)

Bin Subhan, Mohammed; Watson, Matthew; Liu, Zhongkai; Walters, Andrew; Hoesch, Moritz; Howard, Chris; Diamond I05 beamline Collaboration

Transition-metal dichalcogenides (TMDCs) are a group of layered materials that exhibit a rich array of electronic ground states including semiconductivity, metallicity, superconductivity and charge density waves. In recent years, 2D TMDCs have attracted considerable attention due to their unique properties and potential applications in optoelectronics. It has been shown that the charge carrier density in few layer MoS2 can be tunably increased via electrostatic gating. At high levels of doping, MoS2 exhibits superconductivity with a dome-like dependence of Tc on doping analogous to that found in the cuprate superconductors. High doping can also be achieved via intercalation of alkali metals in bulk MoS2. The origin of this superconductivity is not yet fully understood with predictions ranging from exotic pairing mechanisms in bulk systems to Ising superconductivity in single layers. Despite these interesting properties, there has been limited research to date on the electronic structure of these doped compounds. Here we present our work on alkali metal intercalated MoS2 using the low temperature metal ammonia solution method. Using X-ray diffraction, Raman spectroscopy and ARPES measurements we will discuss the physical and electronic structure of these materials. EPSRC, Diamond Light Source.

Application of glass particles doped by Zn{sup +2} as an antimicrobial and atoxic compound in LLDPE and HDPE

Energy Technology Data Exchange (ETDEWEB)

Santos, M.F. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarianese/UNESC, Av. Universitária, 1105, CEP 88806-000, Criciúma, Santa Catarina (Brazil); Machado, C.; Tachinski, C.G.; Júnior, J.F.; Piletti, R. [Laboratory of Advanced Materials and Processes, Universidade do Extremo Sul Catarianese/UNESC, iParque, Rod. Gov. Jorge Lacerda, km 4,5, CEP 88806-000, Criciúma, SC (Brazil); Peterson, M. [Post-Graduate Program in Science and Materials Engineering, Universidade do Extremo Sul Catarianese/UNESC, Av. Universitária, 1105, CEP 88806-000, Criciúma, Santa Catarina (Brazil); Laboratory of Advanced Materials and Processes, Universidade do Extremo Sul Catarianese/UNESC, iParque, Rod. Gov. Jorge Lacerda, km 4,5, CEP 88806-000, Criciúma, SC (Brazil); Fiori, M.A., E-mail: fiori@unochapeco.edu.br [Post-Graduation Program in Environmental Science, Universidade Comunitária da Região de Chapecó (Unochapecó), Chapecó, SC (Brazil); Post-Graduation Program in Technology and Management of the Innovation, Universidade Comunitária da Região de Chapecó (Unochapecó), Chapecó, SC (Brazil)

2014-06-01

This study demonstrates the potential application of glass particles doped with Zn{sup +2} (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0 ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00 wt.% and at a time of 4 h, the bactericidal performance is excellent and equal for both polymeric compounds. - Highlights: • Glass doped with Zn{sup +2} (GZn) promoted a good bactericidal properties in LLDPE and HDPE. • LLDPE and HDPE doped with GZn have capacity of liberty ionic zinc during a time period. • GZn is not toxic to human and can be used with antimicrobial additive to polymers. • GZn has an antimicrobial effect in bacteria type Gram positive and Gram negative.

Investigating the electronic properties of multi-junction ZnS/CdS/CdTe graded bandgap solar cells

Energy Technology Data Exchange (ETDEWEB)

Olusola, O.I., E-mail: olajideibk@yahoo.com [Electronic Materials and Sensors Group, Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom); Department of Physics, School of Science, The Federal University of Technology, Akure (FUTA), P.M.B. 704 (Nigeria); Madugu, M.L.; Dharmadasa, I.M. [Electronic Materials and Sensors Group, Materials and Engineering Research Institute, Sheffield Hallam University, Sheffield S1 1WB (United Kingdom)

2017-04-15

The fabrication of multi-junction graded bandgap solar cells have been successfully implemented by electroplating three binary compound semiconductors from II-VI family. The three semiconductor materials grown by electroplating techniques are ZnS, CdS and CdTe thin films. The electrical conductivity type and energy bandgap of each of the three semiconductors were determined using photoelectrochemical (PEC) cell measurement and UV–Vis spectrophotometry techniques respectively. The PEC cell results show that all the three semiconductor materials have n-type electrical conductivity. These two material characterisation techniques were considered in this paper in order to establish the relevant energy band diagram for device results, analysis and interpretation. Solar cells with the device structure glass/FTO/n-ZnS/n-CdS/n-CdTe/Au were then fabricated and characterised using current-voltage (I-V) and capacitance-voltage (C-V) techniques. From the I-V characteristics measurement, the fabricated device structures yielded an open circuit voltage (V{sub oc}) of 670 mV, short circuit current density (J{sub sc}) of 41.5 mA cm{sup −2} and fill-factor (FF) of 0.46 resulting in ∼12.8% efficiency when measured at room temperature under AM1.5 illumination conditions. The device structure showed an excellent rectification factor (RF) of 10{sup 4.3} and ideality factor (n) of 1.88. The results obtained from the C-V measurement also showed that the device structures have a moderate doping level of 5.2 × 10{sup 15} cm{sup −3}. - Highlights: • Electroplating of n-ZnS, n-CdS and n-CdTe binary compound semiconductors. • Fabrication of Schottky barrier solar cells from glass/FTO/n-ZnS/n-CdS/n-CdTe/Au. • Development of multi-junction graded bandgap solar cells using n-n-n structures.

Photoluminescence studies on Cd(1-x)Zn(x)S:Mn2+ nanocrystals.

Science.gov (United States)

Sethi, Ruchi; Kumar, Lokendra; Pandey, A C

2009-09-01

Highly monodispersed, undoped and doped with Mn2+, binary and ternary (CdS, ZnS, Cd(1-x)Zn(x)S) compound semiconductor nanocrystals have been synthesized by co-precipitation method using citric acid as a stabilizer. As prepared sample are characterized by X-ray diffraction, Small angle X-ray scattering, Transmission electron microscope, Optical absorption and Photoluminescence spectroscopy, for their optical and structural properties. X-ray diffraction, Small angle X-ray scattering and Transmission electron microscope results confirm the preparation of monodispersed nanocrystals. Photoluminescence studies show a significant blue shift in the wavelength with an increasing concentration of Zn in alloy nanocrystals.

Photoluminescent properties of Pr3+ doped YTiAO6 (A= Nb&Ta) euxenite compounds

Science.gov (United States)

Venugopal, Meenu; Kumar, H. Padma

2018-04-01

Pr3+ doped YTiAO6 (A = Nb and Ta) compounds were prepared by conventional solid state ceramic route. X - ray diffraction studies of the samples confirmed the euxenite orthorhombic phase formation. Effect of Pr3+ doping on the optical and luminescence properties of YTiAO6 (A = Nb and Ta) were studied. The strong absorption in the UV region are due to the absorption by the host YTiAO6 (A = Nb and Ta) and all other peaks can be attributed to that of Pr3+. Host emission peaks are observed around 485 nm and 460 nm in all samples. The red emission observed at 614 nm in the doped samples corresponds to the 1D2 to 3H4 transition of Pr3+ ion. CIE colour coordinates and chromaticity values were also discussed.

Diverse Cd(II) compounds based on N-benzoyl-L-glutamic acid and N-donor ligands: Structures and photoluminescent properties

International Nuclear Information System (INIS)

Ma, Ning; Guo, Wei-Ying; Song, Hui-Hua; Yu, Hai-Tao

2016-01-01

Five new Cd(II) coordination polymers with N-benzoyl-L-glutamic acid (H_2bzgluO) and different N-donor ligands, [Cd(bzgluO)(2,2′-bipy)(H_2O)]_n (1), [Cd(bzgluO)(2,4′-bipy)_2(H_2O)·3H_2O]_n (2), [Cd(bzgluO)(phen)·H_2O]_n (3), [Cd(bzgluO)(4,4′-bipy)(H_2O)]_n (4), [Cd(bzgluO)(bpp)(H_2O)·2H_2O]_n (5) were synthesized (2,2′-bipy=2,2′-bipyridine, 2,4′-bipy=2,4′-bipyridine, phen=1,10-phenanthroline, 4,4′-bipy=4,4′-bipyridine, bpp=1,3-di(4-pyridyl)propane). Compounds 1–2 exhibit a 1D single-chain structure. Compound 1 generates a 2D supramolecular structure via π–π stacking and hydrogen bonding, 3D architecture of compound 2 is formed by hydrogen bonding. Compound 3 features a 1D double-chain structure, which are linked by π–π interactions into a 2D supramolecular layer. Compounds 4-5 display a 2D network structure. Neighboring layers of 4 are extended into a 3D supramolecular architecture through hydrogen bonding. The structural diversity of these compounds is attributed to the effect of ancillary N-donor ligands and coordination modes of H_2bzgluO. Luminescent properties of 1–5 were studied at room temperature. Circular dichroism of compounds 1, 2 and 5 were investigated. - Graphical abstract: Five new Cd(II) metal coordination compounds with H_2bzgluO and different N-donor ligands were synthesized and characterized. Compounds 1, 2 and 3 present 1D structures, compounds 4 and 5 display 2D networks. Results indicate that auxiliary ligands and coordination modes of H_2bzgluO play an important role in governing the formation of final frameworks, and the hydrogen-bonding and π–π stacking interactions contribute the formation of the diverse supramolecular architectures. Furthermore, the different crystal structures influence the emission spectra significantly. - Highlights: • It is rarely reported that complexes prepared with N-benzoyl-L-glutamic acid. • Each complex displays diverse structures and different supramolecular

Growth of wurtzite CdTe nanowires on fluorine-doped tin oxide glass substrates and room-temperature bandgap parameter determination

Science.gov (United States)

Choi, Seon Bin; Song, Man Suk; Kim, Yong

2018-04-01

The growth of CdTe nanowires, catalyzed by Sn, was achieved on fluorine-doped tin oxide glass by physical vapor transport. CdTe nanowires grew along the 〈0001〉 direction, with a very rare and phase-pure wurtzite structure, at 290 °C. CdTe nanowires grew under Te-limited conditions by forming SnTe nanostructures in the catalysts and the wurtzite structure was energetically favored. By polarization-dependent and power-dependent micro-photoluminescence measurements of individual nanowires, heavy and light hole-related transitions could be differentiated, and the fundamental bandgap of wurtzite CdTe at room temperature was determined to be 1.562 eV, which was 52 meV higher than that of zinc-blende CdTe. From the analysis of doublet photoluminescence spectra, the valence band splitting energy between heavy hole and light hole bands was estimated to be 43 meV.

Stabilization of Fermi level via electronic excitation in Sn doped CdO thin films

Science.gov (United States)

Das, Arkaprava; Singh, Fouran

2018-04-01

Pure and Sn doped CdO sol-gel derived thin films were deposited on corning glass substrate and further irradiated by swift heavy ion (SHI) (Ag and O) with fluence upto 3×1013 ions/cm2. The observed tensile stress from X-ray diffraction pattern at higher fluence for Ag ions can be corroborated to the imbrications of cylindrical tracks due to multiple impacts. The anomalous band gap enhancement after irradiation may be attributed to the consolidated effect of Burstein-Moss shift (BMS) and impurity induced virtual gap states (ViGs). At higher excitation density as Fermi stabilization level (EFS) tends to coincide with charge neutrality level (CNL), band gap enhancement saturates as further creation of additional defects inside the lattice becomes unsustainable. Raman spectroscopy divulges an intensity enhancement of 478 cm-1 LO phonon mode with Sn doping and irradiation induces further asymmetric peak broadening due to damage and disordering inside the lattice. However for 3% Sn doped thin film irradiated with Ag ions having 3×1013 fluence shows a drastic change in structural properties and reduction in band gap which might be attributed to the generation of localized energy levels between conduction and valance band due to high density of defects.

Synthesis and study of optical and thermal properties of Mn doped CdS nanoparticles using polyvinylpyrrolidone

International Nuclear Information System (INIS)

Rajesh Kumar, M.; Murugadoss, G.

2014-01-01

High quality and monodispersed CdS:Mn (1–5%) nanoparticles were synthesized by chemical precipitation method using PVP as surfactant. The structure and morphology of the CdS:Mn were investigated by means of XRD, FT-IR, TEM, UV–visible, PL, EPR and TG-DTA. XRD study was confirmed the formation cubic structured CdS:Mn nanoparticles. The optical absorption of Mn doped CdS nanoparticles was found to be 420–432 nm, which is significantly decreased from the bulk CdS material. Photoluminescence spectroscopy of the CdS:Mn nanocrystals showed a strong emission peak at 535 nm near the band edge along with a week green emission around 575 nm. The PL property of annealed (255 °C–850 °C) samples was also investigated under different excitations. The presence of PVP on the CdS:Mn surface and incorporated the Mn ion into CdS lattice were identified by FT-IR and EPR spectroscopy, respectively. TEM result showed spherical with monodispersed particles with typical size of 3.8–4.3 nm, which is a favorable characteristic for many applications. The major weight loss and gain were found in the thermogravimetric analysis (TGA) which corresponds to the decomposition and oxidation of the samples. -- Highlights: • An optimum concentration of Mn was selected through optical study. • PL emission was improved by addition of capping agent. • The PL enhancement indicates good crystal quality and monodisperse of the synthesized CdS:Mn nanoparticles by chemical method

Effect of Gallium Doping on the Characteristic Properties of Polycrystalline Cadmium Telluride Thin Film

Science.gov (United States)

Ojo, A. A.; Dharmadasa, I. M.

2017-08-01

Ga-doped CdTe polycrystalline thin films were successfully electrodeposited on glass/fluorine doped tin oxide substrates from aqueous electrolytes containing cadmium nitrate (Cd(NO3)2·4H2O) and tellurium oxide (TeO2). The effects of different Ga-doping concentrations on the CdTe:Ga coupled with different post-growth treatments were studied by analysing the structural, optical, morphological and electronic properties of the deposited layers using x-ray diffraction (XRD), ultraviolet-visible spectrophotometry, scanning electron microscopy, photoelectrochemical cell measurement and direct-current conductivity test respectively. XRD results show diminishing (111)C CdTe peak above 20 ppm Ga-doping and the appearance of (301)M GaTe diffraction above 50 ppm Ga-doping indicating the formation of two phases; CdTe and GaTe. Although, reductions in the absorption edge slopes were observed above 20 ppm Ga-doping for the as-deposited CdTe:Ga layer, no obvious influence on the energy gap of CdTe films with Ga-doping were detected. Morphologically, reductions in grain size were observed at 50 ppm Ga-doping and above with high pinhole density within the layer. For the as-deposited CdTe:Ga layers, conduction type change from n- to p- were observed at 50 ppm, while the n-type conductivity were retained after post-growth treatment. Highest conductivity was observed at 20 ppm Ga-doping of CdTe. These results are systematically reported in this paper.

em>Ab initio em>LSDA and LSDA+em>U em>study of pure and Cd-doped cubic lanthanide sesquioxides

DEFF Research Database (Denmark)

Richard, D.; Muñoz, E.L.; Rentería, M.

2013-01-01

The electronic, structural, and hyperfine properties of pure and Cd-doped lanthanide (Ln) sesquioxides with the cubic bixbyite structure (Ln2O3, Ln ranging from La to Lu) have been studied using the full-potential augmented plane wave plus local orbital (APW+lo) method within the local spin density...

Energy- and temperature dependences of secondary electron emission of CsI- and CsBr layers doped with Cd

International Nuclear Information System (INIS)

Galij, P.V.; Tsal', N.A.

1983-01-01

The energy and temperature dependences of the secondary electron emission coefficient (SEEC) of CsI-Cd-, CsBr-Cd-, CsI-CsBr layers have been studied. The effect of bivalent cadmium impurity on the SEEC value is investigated. It is shown that implantation of small amounts of Cd 2+ impurity into the lattice of the initial monocrystals might increase the SEEC values of the layers. Temperature dependences (TD) of SEEC are measured and the possibility of comparing experimental results with the Dekker formula is analyzed. A conclusion is drawn that the Dekker model well describes the TD of SEEC of doped layers at temperatures T < or approximately 100 deg C. At elevated temperatures., along with secondary electron scattering on phonons, one should take into account their scattering on vacancies

Diverse Cd(II) compounds based on N-benzoyl-L-glutamic acid and N-donor ligands: Structures and photoluminescent properties

Energy Technology Data Exchange (ETDEWEB)

Ma, Ning; Guo, Wei-Ying; Song, Hui-Hua, E-mail: songhuihua@mail.hebtu.edu.cn; Yu, Hai-Tao, E-mail: haitaoyu@mail.hebtu.edu.cn

2016-01-15

Five new Cd(II) coordination polymers with N-benzoyl-L-glutamic acid (H{sub 2}bzgluO) and different N-donor ligands, [Cd(bzgluO)(2,2′-bipy)(H{sub 2}O)]{sub n} (1), [Cd(bzgluO)(2,4′-bipy){sub 2}(H{sub 2}O)·3H{sub 2}O]{sub n} (2), [Cd(bzgluO)(phen)·H{sub 2}O]{sub n} (3), [Cd(bzgluO)(4,4′-bipy)(H{sub 2}O)]{sub n} (4), [Cd(bzgluO)(bpp)(H{sub 2}O)·2H{sub 2}O]{sub n} (5) were synthesized (2,2′-bipy=2,2′-bipyridine, 2,4′-bipy=2,4′-bipyridine, phen=1,10-phenanthroline, 4,4′-bipy=4,4′-bipyridine, bpp=1,3-di(4-pyridyl)propane). Compounds 1–2 exhibit a 1D single-chain structure. Compound 1 generates a 2D supramolecular structure via π–π stacking and hydrogen bonding, 3D architecture of compound 2 is formed by hydrogen bonding. Compound 3 features a 1D double-chain structure, which are linked by π–π interactions into a 2D supramolecular layer. Compounds 4-5 display a 2D network structure. Neighboring layers of 4 are extended into a 3D supramolecular architecture through hydrogen bonding. The structural diversity of these compounds is attributed to the effect of ancillary N-donor ligands and coordination modes of H{sub 2}bzgluO. Luminescent properties of 1–5 were studied at room temperature. Circular dichroism of compounds 1, 2 and 5 were investigated. - Graphical abstract: Five new Cd(II) metal coordination compounds with H{sub 2}bzgluO and different N-donor ligands were synthesized and characterized. Compounds 1, 2 and 3 present 1D structures, compounds 4 and 5 display 2D networks. Results indicate that auxiliary ligands and coordination modes of H{sub 2}bzgluO play an important role in governing the formation of final frameworks, and the hydrogen-bonding and π–π stacking interactions contribute the formation of the diverse supramolecular architectures. Furthermore, the different crystal structures influence the emission spectra significantly. - Highlights: • It is rarely reported that complexes prepared with N-benzoyl-L-glutamic acid

In situ generated CdS nanostructure induced enhanced photoluminescence from Dy{sup 3+} ions doped dielectric nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Dey, Chirantan; Karmakar, Basudeb [Glass Science and Technology Section, Glass Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India)

2017-08-15

We report CdS nanostructure induced enhanced photoluminescence (PL) from Dy{sup +3}:CdS co-doped dielectric-nanocomposites synthesized by the conventional melt-quench technique. CdS nanocrystals (NCs) were synthesized as in situ within the dielectric medium and their growth was controlled by heat treatment duration. Nanoparticles were investigated with absorption spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and Raman spectroscopy. The experimentally obtained sizes of the NCs are found to increase from 5-11 nm to 50-80 nm. Bandgap enhancement for the carrier confinement was found to alter within the range of 0.20-0.38 eV. Phonon confinement effect has been confirmed by blue shifting of Raman peak for CdS NCs at 303 cm{sup -1}. Enhanced highly intense sharp PL peak at 576 nm was detected, and different parameters associated with the PL enhancement including energy transfer from CdS NCs to Dy{sup 3+} ions have been studied. This PL enhancement was steered by varying CdS NC sizes. Enhanced PL of these nanocomposites finds their potential applications as gain medium in the field of solid state lasers. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and optical properties of CdS/ZnS coreshell nanoparticles

International Nuclear Information System (INIS)

Saraswathi Amma, B.; Manzoor, K.; Ramakrishna, K.; Pattabi, Manjunatha

2008-01-01

Synthesis and optical properties of manganese (Mn 2+ )-doped, polyvinyl pyrrolidone (PVP)-capped cadmium sulphide (CdS) nanoparticles coated with zinc sulphide (ZnS) are reported. Colloidal solution of Mn 2+ -doped CdS nanoparticles capped with PVP is synthesized using methanol as solvent. PVP is used to control the particle size and to prevent agglomeration. Mn 2+ doping is expected to help in increasing the CdS band edge photoluminescence (PL) emission. Addition of zinc nitrate and sodium sulphide alternately to the Mn 2+ -doped, PVP-stabilized CdS colloid led to the formation of ZnS-coated CdS coreshell nanoparticles. Photoluminescence emission spectra recorded for (CdS-PVP)Mn nanoparticles showed two emission peaks, one at 416 nm and the other weaker peak at 586 nm which is attributed to Mn 2+ emission. Intensity of Mn 2+ peak increased with increase in the Mn 2+ content. Mn 2+ emission disappears when ZnS is coated over the CdS core, resulting in pure CdS band edge emission

Theoretical study of EPR spectra in Cu2+ - and Mn2+ - doped CaCd(CH3COO)4.6H2O

International Nuclear Information System (INIS)

Zhou Yiyang; Zhao Minguang

1987-08-01

The EPR spectra of CaCd(CH 3 COO) 4 .6H 2 O doped with Cu 2+ and Mn 2+ have been studied theoretically. A comparison between the calculated results and the experimental data shows quantitatively that the Cu 2+ and Mn 2+ ions substitute for the Cd 2+ and Ca 2+ ions, respectively. This conclusion is consistent with the qualitative assumption given by previous authors. (author). 36 refs, 1 fig., 3 tabs

One-pot noninjection synthesis of Cu-doped Zn(x)Cd(1-x)S nanocrystals with emission color tunable over entire visible spectrum.

Science.gov (United States)

Zhang, Wenjin; Zhou, Xinggui; Zhong, Xinhua

2012-03-19

Unlike Mn doped quantum dots (d-dots), the emission color of Cu dopant in Cu d-dots is dependent on the nature, size, and composition of host nanocrystals (NCs). The tunable Cu dopant emission has been achieved via tuning the particle size of host NCs in previous reports. In this paper, for the first time we doped Cu impurity in Zn(x)Cd(1-x)S alloyed NCs and tuned the dopant emission in the whole visible spectrum via variation of the stoichiometric ratio of Zn/Cd precursors in the host Zn(x)Cd(1-x)S alloyed NCs. A facile noninjection and low cost approach for the synthesis of Cu:Zn(x)Cd(1-x)S d-dots was reported. The optical properties and structure of the obtained Cu:Zn(x)Cd(1-x)S d-dots have been characterized by UV-vis spectroscopy, photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The influences of various experimental variables, including Zn/Cd ratio, reaction temperature, and Cu dopant concentration, on the optical properties of Cu dopant emission have been systematically investigated. The as-prepared Cu:Zn(x)Cd(1-x)S d-dots did show PL emission but with quite low quantum yield (QY) (typically below 6%). With the deposition of ZnS shell around the Cu:Zn(x)Cd(1-x)S core NCs, the PL QY increased substantially with a maximum value of 65%. More importantly, the high PL QY can be preserved when the initial oil-soluble d-dots were transferred into aqueous media via ligand replacement by mercaptoundeconic acid. In addition, these d-dots have thermal stability up to 250 °C. © 2012 American Chemical Society

Structural, optical and morphological studies of Cd2+ doping in CH3NH3PbI3 perovskite semiconductor at Pb2+ site for photovoltaic applications

Science.gov (United States)

Parrey, Khursheed; Warish, Mohd.; Devi, Nisha; Niazi, A.; Aziz, A.; Ansari, S. G.

2018-05-01

Doping of semiconductors in a controlled mannner have paramount technological importance as far as the optical and electronic properties of the devices are concerned. Hybrid organic-inorganic perovskites (HOPs) as intrinsic semiconductors have sensational properties required for both the solar photovoltaics and perovskite light emitting diodes. However, undoped and complexity in the dpoing process of HOPs have limited their exploitation in the field of elcronics. In this papper we present the synthesis of HOP semiconductor (CH3NH3PbI3) doped in Pb2+ position by Cd2+. We studied the effect of the incorporation of Cd2+ into the crystalline structure and analysed the changes in the properties like crystal structure, optical absorption and the surface morphology. The structure of HOPs confirmed by X-ray diffraction analysis is tetragonal perovskite type. It can be found that the crystallinity of the samples was enhanced with the doping concentration as the intensity of diffraction peaks were observed to increase with doping. The absorption spectra as obtained from UV-Visible spectrophotometry and Tauc plot analysis indicated that the band gap observed (1.73 eV) is direct type and gets reduced to 1.67 eV with the doping concentration. The red shift may be due to the increase in the size of nanocrystalline material with doping.

Comparative effects of indium/ytterbium doping on, mechanical and gas-sensitivity-related morphological, properties of sprayed ZnO compounds

International Nuclear Information System (INIS)

Boukhachem, A.; Fridjine, S.; Amlouk, A.; Boubaker, K.; Bouhafs, M.; Amlouk, M.

2010-01-01

In this study, conducting and transparent indium-doped zinc oxide (ZnO) thin films have been deposited on glass substrates by the micro-spray technique. First, zinc oxide layers were obtained by spaying a solution of propanol and zinc acetate in acidified medium. Alternatively, some of the obtained films were doped with indium (In) at the molar rates of: 1%, 2% and 3%. In addition to the classical structural investigated using XRD, AFM and SEM techniques, microhardness Vickers (Hv) measurements have been carried out along with comparative morphological prospecting. The specific gases sensitivity-related surface morphology of the doped ZnO compounds was favorably different from that of the non-doped ones, and showed a thin overlay structure. Results were compared to those recorded for similar ytterbium-doped material.

New insights into organic-inorganic hybrid perovskite CH₃NH₃PbI₃ nanoparticles. An experimental and theoretical study of doping in Pb²⁺ sites with Sn²⁺, Sr²⁺, Cd²⁺ and Ca²⁺.

Science.gov (United States)

Navas, Javier; Sánchez-Coronilla, Antonio; Gallardo, Juan Jesús; Hernández, Norge Cruz; Piñero, Jose Carlos; Alcántara, Rodrigo; Fernández-Lorenzo, Concha; De los Santos, Desireé M; Aguilar, Teresa; Martín-Calleja, Joaquín

2015-04-14

This paper presents the synthesis of the organic-inorganic hybrid perovskite, CH3NH3PbI3, doped in the Pb(2+) position with Sn(2+), Sr(2+), Cd(2+) and Ca(2+). The incorporation of the dopants into the crystalline structure was analysed, observing how the characteristics of the dopant affected properties such as the crystalline phase, emission and optical properties. XRD showed how doping with Sn(2+), Sr(2+) and Cd(2+) did not modify the normal tetragonal phase. When doping with Ca(2+), the cubic phase was obtained. Moreover, DR-UV-Vis spectroscopy showed how the band gap decreased with the dopants, the values following the trend Sr(2+) Ca(2+) Cd(2+) > Sr(2+) for the tetragonal structure and Pb(2+) > Ca(2+) for the cubic phase. The electron localization function (ELF) analysis showed similar electron localizations for undoped and Sn(2+)-doped tetragonal structures, which were different from those doped with Sr(2+) and Cd(2+). Furthermore, when Cd(2+) was incorporated, the Cd-I interaction was strengthened. For Ca(2+) doping, the Ca-I interaction had a greater ionic nature than Cd-I. Finally, an analysis based on the non-covalent interaction (NCI) index is presented to determine the weak-type interactions of the CH3NH3 groups with the dopant and I atoms. To our knowledge, this kind of analysis with these hybrid systems has not been performed previously.

Lattice defects in semiconducting Hg/1-x/Cd/x/Te alloys. I - Defect structure of undoped and copper doped Hg/0.8/Cd/0.2/Te. II - Defect structure of indium-doped Hg/0.8/Cd/0.2/Te

Science.gov (United States)

Vydyanath, H. R.

1981-01-01

Hall effect and mobility measurements were conducted on undoped Hg(0.8)Cd(0.2)Te crystals which were quenched to room temperature after being subjected to equilibration at temperatures ranging from 400 to 655 C in various Hg atmospheres. The variation of the hole concentration in the cooled crystals at 77 K as a function of Hg's partial pressure at the equilibration temperature, together with a comparison of the hole mobility in the undoped samples with that in copper-doped ones, yields a defect model for the undoped crystals according to which they are intrinsic at the equilibration temperatures and the native acceptor defects are doubly ionized. In the second part of this paper, the effects of indium doping are considered. The concentration of electrons obtained in the cooled crystals was found to be lower than the intrinsic carrier concentration at the equilibration temperatures. A defect model is proposed according to which most of the indium is incorporated as In2Te3(s) dissolved in the crystal, with only a small fraction of indium acting as single donors occupying Hg lattice sites.

The frequency-domain relaxation response of gallium doped Cd{sub 1-x}Mn{sub x}Te

Energy Technology Data Exchange (ETDEWEB)

Trzmiel, Justyna; Weron, Karina [Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Jurlewicz, Agnieszka [Hugo Steinhaus Center, Institute of Mathematics and Computer Science, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)

2010-03-10

In this paper the complex dielectric permittivity of gallium doped Cd{sub 0.99}Mn{sub 0.01}Te mixed crystals is studied at different temperatures. We observe a two-power-law relaxation pattern with m and n, the low- and high-frequency power-law exponents respectively, satisfying the relation m < 1 - n. To interpret the empirical result we propose a correlated-cluster relaxation mechanism. This approach allows us to find origins of both power-law exponents, m and n.

Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

International Nuclear Information System (INIS)

Sujan, G.K.; Haseeb, A.S.M.A.; Afifi, A.B.M.

2014-01-01

Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu 6 Sn 5 from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping of flux

Effects of metallic nanoparticle doped flux on the interfacial intermetallic compounds between lead-free solder ball and copper substrate

Energy Technology Data Exchange (ETDEWEB)

Sujan, G.K., E-mail: sgkumer@gmail.com; Haseeb, A.S.M.A., E-mail: haseeb@um.edu.my; Afifi, A.B.M., E-mail: amalina@um.edu.my

2014-11-15

Lead free solders currently in use are prone to develop thick interfacial intermetallic compound layers with rough morphology which are detrimental to the long term solder joint reliability. A novel method has been developed to control the morphology and growth of intermetallic compound layers between lead-free Sn–3.0Ag–0.5Cu solder ball and copper substrate by doping a water soluble flux with metallic nanoparticles. Four types of metallic nanoparticles (nickel, cobalt, molybdenum and titanium) were used to investigate their effects on the wetting behavior and interfacial microstructural evaluations after reflow. Nanoparticles were dispersed manually with a water soluble flux and the resulting nanoparticle doped flux was placed on copper substrate. Lead-free Sn–3.0Ag–0.5Cu solder balls of diameter 0.45 mm were placed on top of the flux and were reflowed at a peak temperature of 240 °C for 45 s. Angle of contact, wetting area and interfacial microstructure were studied by optical microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that the angle of contact increased and wetting area decreased with the addition of cobalt, molybdenum and titanium nanoparticles to flux. On the other hand, wettability improved with the addition of nickel nanoparticles. Cross-sectional micrographs revealed that both nickel and cobalt nanoparticle doping transformed the morphology of Cu{sub 6}Sn{sub 5} from a typical scallop type to a planer one and reduced the intermetallic compound thickness under optimum condition. These effects were suggested to be related to in-situ interfacial alloying at the interface during reflow. The minimum amount of nanoparticles required to produce the planer morphology was found to be 0.1 wt.% for both nickel and cobalt. Molybdenum and titanium nanoparticles neither appear to undergo alloying during reflow nor have any influence at the solder/substrate interfacial reaction. Thus, doping

Substitutional Doping for Aluminosilicate Mineral and Superior Water Splitting Performance

Science.gov (United States)

Zhang, Yi; Fu, Liangjie; Shu, Zhan; Yang, Huaming; Tang, Aidong; Jiang, Tao

2017-07-01

Substitutional doping is a strategy in which atomic impurities are optionally added to a host material to promote its properties, while the geometric and electronic structure evolution of natural nanoclay mineral upon substitutional metal doping is still ambiguous. This paper first designed an efficient lanthanum (La) doping strategy for nanotubular clay (halloysite nanotube, HNT) through the dynamic equilibrium of a substitutional atom in the presence of saturated AlCl3 solution, and systematic characterization of the samples was performed. Further density functional theory (DFT) calculations were carried out to reveal the geometric and electronic structure evolution upon metal doping, as well as to verify the atom-level effect of the La doping. The CdS loading and its corresponding water splitting performance could demonstrate the effect of La doping. CdS nanoparticles (11 wt.%) were uniformly deposited on the surface of La-doped halloysite nanotube (La-HNT) with the average size of 5 nm, and the notable photocatalytic hydrogen evolution rate of CdS/La-HNT reached up to 47.5 μmol/h. The results could provide a new strategy for metal ion doping and constructive insight into the substitutional doping mechanism.

A novel small-molecule compound targeting CD147 inhibits the motility and invasion of hepatocellular carcinoma cells.

Science.gov (United States)

Fu, Zhi-guang; Wang, Li; Cui, Hong-yong; Peng, Jian-long; Wang, Shi-jie; Geng, Jie-jie; Liu, Ji-de; Feng, Fei; Song, Fei; Li, Ling; Zhu, Ping; Jiang, Jian-li; Chen, Zhi-nan

2016-02-23

CD147, a type I transmembrane glycoprotein, is highly expressed in various cancer types and plays important roles in tumor progression, especially by promoting the motility and invasion of hepatocellular carcinoma (HCC) cells. These crucial roles make CD147 an attractive target for therapeutic intervention in HCC, but no small-molecule inhibitors of CD147 have been developed to date. To identify a candidate inhibitor, we used a pharmacophore model derived from the structure of CD147 to virtually screen over 300,000 compounds. The 100 highest-ranked compounds were subjected to biological assays, and the most potent one, dubbed AC-73 (ID number: AN-465/42834501), was studied further. We confirmed that AC-73 targeted CD147 and further demonstrated it can specifically disrupt CD147 dimerization. Moreover, molecular docking and mutagenesis experiments showed that the possible binding sites of AC-73 on CD147 included Glu64 and Glu73 in the N-terminal IgC2 domain, which two residues are located in the dimer interface of CD147. Functional assays revealed that AC-73 inhibited the motility and invasion of typical HCC cells, but not HCC cells that lacked the CD147 gene, demonstrating on-target action. Further, AC-73 reduced HCC metastasis by suppressing matrix metalloproteinase (MMP)-2 via down-regulation of the CD147/ERK1/2/signal transducer and activator of transcription 3 (STAT3) signaling pathway. Finally, AC-73 attenuated progression in an orthotopic nude mouse model of liver metastasis, suggesting that AC-73 or its derivatives have potential for use in HCC intervention. We conclude that the novel small-molecule inhibitor AC-73 inhibits HCC mobility and invasion, probably by disrupting CD147 dimerization and thereby mainly suppressing the CD147/ERK1/2/STAT3/MMP-2 pathways, which are crucial for cancer progression.

Defect formation and carrier doping in epitaxial films of the ''parent'' compound SrCuO2: Synthesis of two superconductors descendants

International Nuclear Information System (INIS)

Feenstra, R.; Norton, D.P.; Budai, J.D.; Jones, E.C.; Christen, D.K.; Kawai, T.

1995-04-01

The infinite layer or parent compounds ACuO 2 (A: Ca-Sr-Ba) constitute the simplest copper oxygen perovskites that contain the CuO 2 sheets essential for superconductivity. The stabilization of these basic ''building blocks'' as epitaxial films, therefore, provides alluring opportunities towards the search for new superconducting compounds and elucidation of the underlying mechanisms. In this work, general trends of the defect formation and carrier doping for epitaxial films of the intermediate endmember SrCuO 2 are reviewed. First results are presented from successful attempts to induce hole-doped superconductivity via the processing-controlled incorporation of charge reservoir layers

Microstructure, mechanical properties, and thermoelectric properties of hot-extruded p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Park, K; Seo, J; Lee, C

1997-07-01

The p-type Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} compounds with Te dopant (4.0 and 6.0 wt%) and without dopant were fabricated by hot extrusion in the temperature range of 300 to 510 C under an extrusion ratio of 20:1. The undoped and Te doped compounds were highly dense and showed high crystalline quality. The grains contained many dislocations and were fine equiaxed ({approximately}1.0 {micro}m) owing to the dynamic recrystallization during the extrusion. The hot extrusion gave rise to the preferred orientation of grains. The bending strength and the figure of merit of the undoped and Te doped compounds were increased with increasing the extrusion temperature. The Te dopant significantly increased the figure of merit. The values of the figure of merit of the undoped and 4.0 wt% Te-doped compounds hot extruded at 440 C were 2.11 x 10{sup {minus}3}/K and 2.94 x 10{sup {minus}3}/K, respectively.

Exploring the doping effects of Ag in p-type PbSe compounds with enhanced thermoelectric performance

Science.gov (United States)

Wang, Shanyu; Zheng, Gang; Luo, Tingting; She, Xiaoyu; Li, Han; Tang, Xinfeng

2011-11-01

In this study, we prepared a series of Ag-doped PbSe bulk materials by a melting-quenching process combined with a subsequent spark plasma sintering process, and systematically investigated the doping effects of Ag on the thermoelectric properties. Ag substitution in the Pb site does not introduce resonant levels near the valence band edge or detectable change in the density of state in the vicinity of the Fermi level, but moves the Fermi level down and increases the carrier concentration to a maximum value of ~4.7 × 1019 cm-3 which is still insufficient for heavily doped PbSe compounds. Nonetheless, the non-monotonic variation in carrier concentration with increasing Ag content indicates that Ag doping reaches the solution limit at ~1.0% and the excessive Ag presumably acts as donors in the materials. Moreover, the large energy gap of the PbSe-based material wipes off significant 'roll-over' in the Seebeck coefficient at elevated temperatures which gives rise to high power factors, being comparable to p-type Te analogues. Consequently, the maximum ZT reaches ~1.0 for the 1.5% Ag-doped samples with optimized carrier density, which is ~70% improvement in comparison with an undoped sample and also superior to the commercialized p-type PbTe materials.

Synthesis and characterization of Fe doped cadmium selenide thin films by spray pyrolysis

Energy Technology Data Exchange (ETDEWEB)

Yadav, Abhijit A., E-mail: aay_physics@yahoo.co.in [Thin Film Physics Laboratory, Department of Physics, Electronics and Photonics, Rajarshi Shahu Mahavidyalaya, Latur 413 512, Maharashtra (India)

2012-12-05

Highlights: Black-Right-Pointing-Pointer Simple and inexpensive method to dope trivalent Fe in CdSe thin films. Black-Right-Pointing-Pointer Fe doped CdSe thin films are highly photosensitive. Black-Right-Pointing-Pointer AFM analysis shows uniform deposition of film over the entire substrate surface. Black-Right-Pointing-Pointer The band gap energy decreases from 1.74 to 1.65 eV with Fe doping. Black-Right-Pointing-Pointer Film resistivity decreases to 6.76 Multiplication-Sign 10{sup 4} {Omega}-cm with Fe doping in CdSe thin films. - Abstract: Undoped and Fe doped CdSe thin films have been deposited onto the amorphous and fluorine doped tin oxide coated glass substrates by spray pyrolysis. The Fe doping concentration has been optimized by photoelectrochemical (PEC) characterization technique. The structural, surface morphological, compositional, optical and electrical properties of undoped and Fe doped CdSe thin films have been studied. X-ray diffraction study reveals that the as deposited CdSe films possess hexagonal crystal structure with preferential orientation along (1 0 0) plane. AFM analysis shows uniform deposition of the film over the entire substrate surface with minimum surface roughness of 7.90 nm. Direct allowed type of transition with band gap decreasing from 1.74 to 1.65 eV with Fe doping has been observed. The activation energy of the films has been found to be in the range of 0.14-0.19 eV at low temperature and 0.27-0.44 eV at high temperature. Semi-conducting behavior has been observed from resistivity measurements. The thermoelectric power measurements reveal that the films are of n type.

Crystalline and Electronic Structures and Magnetic and Electrical Properties of La-Doped Ca2Fe2O5 Compounds

Science.gov (United States)

Phan, T. L.; Tho, P. T.; Tran, N.; Kim, D. H.; Lee, B. W.; Yang, D. S.; Thiet, D. V.; Cho, S. L.

2018-01-01

Brownmillerite Ca2Fe2O5 has been observed to exhibit many outstanding properties that are applicable to ecotechnology. However, very little work on doped Ca2Fe2O5 compounds has been carried out to widen their application scope. We present herein a detailed study of the crystalline/geometric and electronic structures and magnetic and electrical properties of Ca2- x La x Fe2O5 ( x = 0 to 1) prepared by conventional solid-state reaction. X-ray diffraction patterns indicated that the compounds with x = 0 to 0.05 exhibited brownmillerite-type single phase. La doping with higher content ( x ≥ 0.1) stimulated additive formation of Grenier- (LaCa2Fe3O8) and perovskite-type (LaFeO3) phases. Extended x-ray absorption fine structure spectroscopy at the Fe K-edge and electron spin resonance spectroscopy revealed presence of Fe3+ in the parent Ca2Fe2O5 ( x = 0) and both Fe3+ and Fe4+ in the doped compounds ( x ≥ 0.05). The Fe4+ content tended to increase with increasing x. This stimulates ferromagnetic exchange interactions between Fe3+ and Fe4+ ions and directly influences the magnetic properties of Ca2- x La x Fe2O5. Electrical resistivity ( ρ) measurements in the temperature range of T = 20 K to 400 K revealed that all the compounds exhibit insulator behavior; the ρ( T) data for x ≥ 0.1 could be described based on the adiabatic small polaron hopping model.

Crystal structure of a Zn-doped derivative of the Li17Ge4 compound

International Nuclear Information System (INIS)

Lacroix-Orio, L.; Tillard, M.; Belin, C.

2008-01-01

The compound Li 17-ε Zn ε Ge 4 has been obtained as a side product during the preparation of the intermetallic compound Li 8 Zn 2 Ge 3 from the elements. Its structure has been determined from single crystal X-ray diffraction intensities measured at 173 K. It crystallizes in the cubic system, F4-bar3m space group, a = 18.842(1) A, Z = 20. Its crystal structure is slightly different from those so far reported in the literature for the Zn-free phase Li 17 Ge 4 , particularly concerned are the positions and the site occupations of Li atoms. Most likely, these structural variations result from the presence of a small Zn concentration in the compound. The Zn doping atom has been found only at the specific Li 4d site (about 3 at.% Zn)

Heterovalent Cation Substitutional and Interstitial Doping in Semiconductor Sensitizers for Quantum Dot Cosensitized Solar Cell

Directory of Open Access Journals (Sweden)

Ningning Zhang

2015-01-01

Full Text Available Doped films of TiO2/PbS/CdS have been prepared by successive ionic layer adsorption and reaction (SILAR method. Bi- and Ag-doped-PbS quantum dot (QD were produced by admixing Bi3+ or Ag+ during deposition and the existing forms of the doping element in PbS QD were analyzed. The results show that Bi3+ entered the cube space of PbS as donor yielding interstitial doping Bi-doped-PbS QD, while Ag+ replaced Pb2+ of PbS as acceptor yielding substitutional doping Ag-doped-PbS QD. The novel Bi-doped-PbS/CdS and Ag-doped-PbS/CdS quantum dot cosensitized solar cell (QDCSC were fabricated and power conversion efficiency (PCE of 2.4% and 2.2% was achieved, respectively, under full sun illumination.

Dense CdS thin films on fluorine-doped tin oxide coated glass by high-rate microreactor-assisted solution deposition

Energy Technology Data Exchange (ETDEWEB)

Su, Yu-Wei, E-mail: suyuweiwayne@gmail.com [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Ramprasad, Sudhir [Energy Processes and Materials Division, Pacific Northwest National Laboratory, Corvallis, OR 9730 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Han, Seung-Yeol; Wang, Wei [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Ryu, Si-Ok [School of Display and Chemical Engineering, Yeungnam University, 214-1 Dae-dong, Gyeonsan, Gyeongbuk 712-749 (Korea, Republic of); Palo, Daniel R. [Barr Engineering Co., Hibbing, MN 55747 (United States); Paul, Brian K. [School of Mechanical, Industrial and Manufacturing Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States); Chang, Chih-hung [School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, OR 97330 (United States); Microproducts Breakthrough Institute and Oregon Process Innovation Center, Corvallis, Oregon 97330 (United States)

2013-04-01

Continuous microreactor-assisted solution deposition is demonstrated for the deposition of CdS thin films on fluorine-doped tin oxide (FTO) coated glass. The continuous flow system consists of a microscale T-junction micromixer with the co-axial water circulation heat exchanger to control the reacting chemical flux and optimize the heterogeneous surface reaction. Dense, high quality nanocrystallite CdS thin films were deposited at an average rate of 25.2 nm/min, which is significantly higher than the reported growth rate from typical batch chemical bath deposition process. Focused-ion-beam was used for transmission electron microscopy specimen preparation to characterize the interfacial microstructure of CdS and FTO layers. The band gap was determined at 2.44 eV by UV–vis absorption spectroscopy. X-ray photon spectroscopy shows the binding energies of Cd 3d{sub 3/2}, Cd 3d{sub 5/2}, S 2P{sub 3/2} and S 2P{sub 1/2} at 411.7 eV, 404.8 eV, 162.1 eV and 163.4 eV, respectively. - Highlights: ► CdS films deposited using continuous microreactor-assisted solution deposition (MASD) ► Dense nanocrystallite CdS films can be reached at a rate of 25.2 [nm/min]. ► MASD can approach higher film growth rate than conventional chemical bath deposition.

Surface Passivation of CdSe Quantum Dots in All Inorganic Amorphous Solid by Forming Cd1-xZnxSe Shell.

Science.gov (United States)

Xia, Mengling; Liu, Chao; Zhao, Zhiyong; Wang, Jing; Lin, Changgui; Xu, Yinsheng; Heo, Jong; Dai, Shixun; Han, Jianjun; Zhao, Xiujian

2017-02-07

CdSe quantum dots (QDs) doped glasses have been widely investigated for optical filters, LED color converter and other optical emitters. Unlike CdSe QDs in solution, it is difficult to passivate the surface defects of CdSe QDs in glass matrix, which strongly suppress its intrinsic emission. In this study, surface passivation of CdSe quantum dots (QDs) by Cd 1-x Zn x Se shell in silicate glass was reported. An increase in the Se/Cd ratio can lead to the partial passivation of the surface states and appearance of the intrinsic emission of CdSe QDs. Optimizing the heat-treatment condition promotes the incorporation of Zn into CdSe QDs and results in the quenching of the defect emission. Formation of CdSe/Cd 1-x Zn x Se core/graded shell QDs is evidenced by the experimental results of TEM and Raman spectroscopy. Realization of the surface passivation and intrinsic emission of II-VI QDs may facilitate the wide applications of QDs doped all inorganic amorphous materials.

III-V group compound semiconductor light-emitting element having a doped tantalum barrier layer

International Nuclear Information System (INIS)

Oanna, Y.; Ozawa, N.; Yamashita, M.; Yasuda, N.

1984-01-01

Disclosed is a III-V Group compound semiconductor light-emitting element having a III-V Group compound semiconductor body with a p-n junction and including a p-type layer involved in forming the p-n junction; and a multi-layer electrode mounted on the p-type layer of the semiconductor body. The electrode comprises a first layer of gold alloy containing a small amount of beryllium or zinc and formed in direct contact with the p-type layer of the semiconductor body and an uppermost layer formed of gold or aluminum. A tantalum layer doped with carbon, nitrogen and/or oxygen is formed between the first layer and the uppermost layer by means of vacuum vapor deposition

Photoluminescence, reddish orange long persistent luminescence and photostimulated luminescence properties of praseodymium doped CdGeO3 phosphor

International Nuclear Information System (INIS)

Jin, Yahong; Hu, Yihua; Chen, Li; Fu, Yinrong; Mu, Zhongfei; Wang, Tao; Lin, Jun

2014-01-01

Highlights: • A novel phosphor CdGeO 3 :Pr 3+ was synthesized successfully. • The persistent luminescence properties of CdGeO 3 :Pr 3+ were studied. • The photostimulated luminescence properties of CdGeO 3 :Pr 3+ were investigated. • The persistent and photostimulated luminescence mechanisms were discussed in detail. - Abstract: Praseodymium doped CdGeO 3 phosphors were prepared successfully by a conventional high temperature solid-state reaction method. It showed reddish orange long persistent luminescence (LPL) after the short UV-irradiation. The reddish orange photostimulated luminescence (PSL) was also observed upon near infrared stimulation at 980 nm after per-exposure into UV light. The origin of LPL and PSL was identified with the emission from Pr 3+ ions with the aid of traps in host lattice. The optimal concentration of Pr 3+ ions for the brightest photoluminescence (PL) emission and the best LPL characteristic were experimentally to be about 3% and 0.5 mol%, respectively. The trapping and de-trapping processes of charge carriers between shallower and deep traps were illustrated. A model was proposed on the basis of experimental results to study the mechanisms of LPL and PSL

Study of hyperfine parameters in Co-doped tin dioxide using PAC spectroscopy

International Nuclear Information System (INIS)

Ramos, Juliana M.; Carbonari, Artur W.; Martucci, Thiago; Costa, Messias S.; Saxena, Rajendra N.; Vianden, R.; Kessler, P.; Geruschke, T.; Steffens, M.

2011-01-01

PAC technique has been used to measure the hyperfine interactions in nano-structured powder samples of semiconducting SnO 2 doped with Co. The aim of this work is to compare the results of PAC measurements using two different techniques of introducing the radioactive 111 In probe nuclei in the sample of SnO 2 doped with Co. The perturbed gamma-gamma angular correlation (PAC) spectroscopy is used for the measurements of the magnetic hyperfine field (MHF) and the electric field gradient (EFG) at 111 Cd sites in SnO 2 doped with 1% and 2% Co. The measurement of EFG is used to study the defects introduced in the semiconductor material and also for the identification of different phases formed within the compound. The techniques utilized for introducing the radioactive 111 In in the sample are the ion-implantation using radioactive ion beam of 111 In and the chemical process in which 111 InCl 3 solution is added during the preparation of SnO 2 doped with Co using sol gel method. The ion-implantation of 111 In in SnO 2 doped with Co was carried out using the University of Bonn ion-implanter with beam energy of 160 keV. The PAC measurements were carried out with four BaF 2 detector gamma spectrometer in the temperature range of 10-295 K. The results show no significant difference in the values of hyperfine parameters. Both techniques show practically the same electric quadrupole interaction for the substitutional site. The results were compared with previous PAC and Moessbauer measurements of SnO 2 powder samples using 111 In- 111 Cd probe. (author)

Solution-mediated cladding doping of commercial polymer optical fibers

Science.gov (United States)

Stajanca, Pavol; Topolniak, Ievgeniia; Pötschke, Samuel; Krebber, Katerina

2018-03-01

Solution doping of commercial polymethyl methacrylate (PMMA) polymer optical fibers (POFs) is presented as a novel approach for preparation of custom cladding-doped POFs (CD-POFs). The presented method is based on a solution-mediated diffusion of dopant molecules into the fiber cladding upon soaking of POFs in a methanol-dopant solution. The method was tested on three different commercial POFs using Rhodamine B as a fluorescent dopant. The dynamics of the diffusion process was studied in order to optimize the doping procedure in terms of selection of the most suitable POF, doping time and conditions. Using the optimized procedure, longer segment of fluorescent CD-POF was prepared and its performance was characterized. Fiber's potential for sensing and illumination applications was demonstrated and discussed. The proposed method represents a simple and cheap way for fabrication of custom, short to medium length CD-POFs with various dopants.

The effect of hydrostatic pressure on conductivity behaviour of needle crystals of iodine and oxygen doped niobium-sulphur compounds

International Nuclear Information System (INIS)

Balla, D.D.; Bondarenko, A.V.; Obolenskij, M.A.; Beletskij, V.I.; Chashka, Kh.B.

1985-01-01

The effect of the hydrostatic pressures up to 11 kbar on conductivity behaviour of the needle crystal of iodine and oxygen doped niobium-sulphur compounds were studied in the temperature range 4.2-300 K. It is shown that in the temperature range 110-300 K conductivity is thermal activated (P=1 bar). Below 110 K the Mott characteristic is observed. Under hydrostatic pressure the deviations from Mott characteristic occurs. The analysis of data suggested that crystals are doped semiconductors

Electrochemical oxidation of nitrogen-heterocyclic compounds at boron-doped diamond electrode.

Science.gov (United States)

Xing, Xuan; Zhu, Xiuping; Li, Hongna; Jiang, Yi; Ni, Jinren

2012-01-01

Nitrogen-heterocyclic compounds (NHCs) are toxic and bio-refractory contaminants widely spread in environment. This study investigated electrochemical degradation of NHCs at boron-doped diamond (BDD) anode with particular attention to the effect of different number and position of nitrogen atoms in molecular structure. Five classical NHCs with similar structures including indole (ID), quinoline (QL), isoquinoline (IQL), benzotriazole (BT) and benzimidazole (BM) were selected as the target compounds. Results of bulk electrolysis showed that degradation of all NHCs was fit to a pseudo first-order equation. The five compounds were degraded with the following sequence: ID>QL>IQL>BT>BM in terms of their rates of oxidation. Quantum chemical calculation was combined with experimental results to describe the degradation character of NHCs at BDD anode. A linear relationship between degradation rate and delocalization energy was observed, which demonstrated that electronic charge was redistributed through the conjugation system and accumulated at the active sites under the attack of hydroxyl radicals produced at BDD anode. Moreover, atom charge was calculated by semi empirical PM3 method and active sites of NHCs were identified respectively. Analysis of intermediates by GC-MS showed agreement with calculation results. Copyright © 2011 Elsevier Ltd. All rights reserved.

Exploring the doping effects of Ag in p-type PbSe compounds with enhanced thermoelectric performance

International Nuclear Information System (INIS)

Wang Shanyu; Zheng Gang; Luo Tingting; She Xiaoyu; Li Han; Tang Xinfeng

2011-01-01

In this study, we prepared a series of Ag-doped PbSe bulk materials by a melting-quenching process combined with a subsequent spark plasma sintering process, and systematically investigated the doping effects of Ag on the thermoelectric properties. Ag substitution in the Pb site does not introduce resonant levels near the valence band edge or detectable change in the density of state in the vicinity of the Fermi level, but moves the Fermi level down and increases the carrier concentration to a maximum value of ∼4.7 × 10 19 cm -3 which is still insufficient for heavily doped PbSe compounds. Nonetheless, the non-monotonic variation in carrier concentration with increasing Ag content indicates that Ag doping reaches the solution limit at ∼1.0% and the excessive Ag presumably acts as donors in the materials. Moreover, the large energy gap of the PbSe-based material wipes off significant 'roll-over' in the Seebeck coefficient at elevated temperatures which gives rise to high power factors, being comparable to p-type Te analogues. Consequently, the maximum ZT reaches ∼1.0 for the 1.5% Ag-doped samples with optimized carrier density, which is ∼70% improvement in comparison with an undoped sample and also superior to the commercialized p-type PbTe materials.

Scandium-doped zinc cadmium oxide as a new stable n-type oxide thermoelectric material

DEFF Research Database (Denmark)

Han, Li; Christensen, Dennis Valbjørn; Bhowmik, Arghya

2016-01-01

Scandium-doped zinc cadmium oxide (Sc-doped ZnCdO) is proposed as a new n-type oxide thermoelectric material. The material is sintered in air to maintain the oxygen stoichiometry and avoid instability issues. The successful alloying of CdO with ZnO at a molar ratio of 1 : 9 significantly reduced...... is a good candidate for improving the overall conversion efficiencies in oxide thermoelectric modules. Meanwhile, Sc-doped ZnCdO is robust in air at high temperatures, whereas other n-type materials, such as Al-doped ZnO, will experience rapid degradation of their electrical conductivity and ZT....

Characterization of some electronic spectral parameters for doped Nd (III) ion in saturated aqueous solution of some pharmaceutical compounds

International Nuclear Information System (INIS)

Naulakha, Neelam; Soni, K.P.; Bhati, P.R.

2000-01-01

The stereo-environment of doped Nd(III) ion in various saturated solutions of some medicinal compounds has been studied for various electronic spectral parameters. The various electronic parameters, viz., Slater Condon (F k ), Lande (ζ 4f ) intensity of hypersensitive band ( 4 G 5/2 ), bonding parameter (b 1/2 ), Judd-Ofelt parameter (Tλ) and Racah parameter (E k ) for Nd(III) ion doped in saturated solution of diphenylhydramine, tripelennamine, chlorophenaramine, promethazine, terfinadine, naproxen, fenoprofen, flurbiprofen, oxaprozine, ketoprofen and ibuprofen have been studied. (author)

Boron-doped cadmium oxide composite structures and their electrochemical measurements

Energy Technology Data Exchange (ETDEWEB)

Lokhande, B.J., E-mail: bjlokhande@yahoo.com [Lab of Smart Mtrls Supercapacitive and Energy Studies, School of Physical Sciences, Solapur University, Solapur 413255, Maharashtra (India); Ambare, R.C. [Lab of Smart Mtrls Supercapacitive and Energy Studies, School of Physical Sciences, Solapur University, Solapur 413255, Maharashtra (India); Mane, R.S. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606 (India); Bharadwaj, S.R. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

2013-08-01

Graphical abstract: Conducting nano-fibrous 3% boron doped cadmium oxide thin films were prepared by SILAR and its super capacitive properties were studied. - Highlights: • Samples are of nanofibrous nature. • All samples shows pseudocapacitive behavior. • 3% B doped CdO shows good specific capacitance. • 3% B doped CdO shows maximum 74.93% efficiency at 14 mA/cm{sup 2}. • 3% B doped CdO shows 0.8 Ω internal resistance. - Abstract: Boron-doped and undoped cadmium oxide composite nanostructures in thin film form were prepared onto stainless steel substrates by a successive ionic layer adsorption and reaction method using aqueous solutions of cadmium nitrate, boric acid and 1% H{sub 2}O{sub 2}. As-deposited films were annealed at 623 K for 1 h. The X-ray diffraction study shows crystalline behavior for both doped and undoped films with a porous topography and nano-wires type architecture, as observed in SEM image. Wettability test confirms the hydrophilic surface with 58° contact angle value. Estimated band gap energy is around 1.9 eV. Electrochemical behavior of the deposited films is attempted in 1 M KOH electrolyte using cyclic voltammetry (CV), electrochemical impedance spectroscopy and galvanostatic charge–discharge tests. Maximum values of the specific capacitance, specific energy and specific power obtained for 3% B doped CdO film at 2 mV/s scan rate are 20.05 F/g, 1.22 Wh/kg and 3.25 kW/kg, respectively.

(Sr{sub 1-x}Na{sub x})(Cd{sub 1-x}Mn{sub x}){sub 2}As{sub 2}: A new charge and spin doping decoupled diluted magnetic semiconductors with CaAl{sub 2}Si{sub 2}-type structure

Energy Technology Data Exchange (ETDEWEB)

Chen, Bijuan; Deng, Zheng; Li, Wenmin; Gao, Moran; Zhao, Guoqiang; Yu, Shuang; Wang, Xiancheng; Liu, Qingqing [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Li, Zhi [School of Materials Science and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Jin, Changqing, E-mail: Jin@iphy.ac.cn [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Quantum Matter, Beijing 100190 (China)

2016-08-28

We report the synthesis and characterization of a new bulk diluted ferromagnetic semiconductor via Na and Mn co-doping in SrCd{sub 2}As{sub 2} with a hexagonal CaAl{sub 2}Si{sub 2}-type structure. Together with carrier doping via (Sr,Na) substitution, spin doping via (Cd,Mn) substitution results in ferromagnetic order with Curie temperature of T{sub C} up to 13 K. Negative magnetoresistance is assigned to weak localization at low temperatures, where the magnetization of samples becomes saturated. The hexagonal structure of (Sr{sub 1−x}Na{sub x})(Cd{sub 1−x}Mn{sub x}){sub 2}As{sub 2} can be acted as a promising candidate for spin manipulations owing to its relatively small coercive field of less than 24 Oe.

On the relaxation rate distribution of the photoionized DX centers in indium doped Cd1-xMnxTe

International Nuclear Information System (INIS)

Trzmiel, J; Placzek-Popko, E; Gumienny, Z; Weron, K; Becla, P

2009-01-01

It was recently shown that the kinetics of persistent photoconductivity (PPC) build-up in indium doped Cd 1-x Mn x Te are non-exponential and can be described solely by the stretched-exponential function. The non-exponentiality is attributed to the indium related DX centers present in the materials. In order to explain this observation, low temperature photoconductivity build-up was studied for Cd 1-x Mn x Te:In of two different manganese contents. It was found that this type of response has its origin in the heavy-tailed distribution of the DX centers. The distribution was analyzed in terms of photon flux. Increasing photon flux leads to the more dispersive behavior. It was also confirmed that the heavy-tailed distribution is due to the different local configuration of atoms surrounding DX centers in the alloy.

Study of hyperfine parameters in Co-doped tin dioxide using PAC spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Ramos, Juliana M.; Carbonari, Artur W.; Martucci, Thiago; Costa, Messias S.; Saxena, Rajendra N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vianden, R.; Kessler, P.; Geruschke, T.; Steffens, M., E-mail: vianden@hiskp.uni-bonn.d [Rheinische Friedrich-Wilhelms-Universitaet Bonn (HISKP- Bonn) (Germany). Helmholtz - Institut fuer Strahlen- und Kernphysik

2011-07-01

PAC technique has been used to measure the hyperfine interactions in nano-structured powder samples of semiconducting SnO{sub 2} doped with Co. The aim of this work is to compare the results of PAC measurements using two different techniques of introducing the radioactive {sup 111}In probe nuclei in the sample of SnO{sub 2} doped with Co. The perturbed gamma-gamma angular correlation (PAC) spectroscopy is used for the measurements of the magnetic hyperfine field (MHF) and the electric field gradient (EFG) at {sup 111}Cd sites in SnO{sub 2} doped with 1% and 2% Co. The measurement of EFG is used to study the defects introduced in the semiconductor material and also for the identification of different phases formed within the compound. The techniques utilized for introducing the radioactive {sup 111}In in the sample are the ion-implantation using radioactive ion beam of {sup 111}In and the chemical process in which {sup 111}InCl{sub 3} solution is added during the preparation of SnO{sub 2} doped with Co using sol gel method. The ion-implantation of {sup 111}In in SnO{sub 2} doped with Co was carried out using the University of Bonn ion-implanter with beam energy of 160 keV. The PAC measurements were carried out with four BaF{sub 2} detector gamma spectrometer in the temperature range of 10-295 K. The results show no significant difference in the values of hyperfine parameters. Both techniques show practically the same electric quadrupole interaction for the substitutional site. The results were compared with previous PAC and Moessbauer measurements of SnO{sub 2} powder samples using {sup 111}In-{sup 111}Cd probe. (author)

Prospective high thermoelectric performance of the heavily p-doped half-Heusler compound CoVSn

International Nuclear Information System (INIS)

Shi, Hongliang; Ming, Wenmei; Parker, David S.; Du, Mao-Hua; Singh, David J.

2017-01-01

The electronic structure and transport properties of the half-Heusler compound CoVSn are studied in this paper systematically by combining first-principles electronic structure calculations and Boltzmann transport theory. The band structure at the valence-band edge is complex with multiple maxima derived from hybridized transition element d states. The result is a calculated thermopower larger than 200 μV /Κ within a wide range of doping concentrations and temperatures for heavily doped p-type CoVSn. The thermoelectric properties additionally benefit from the corrugated shapes of the hole pockets in our calculated isoenergy surfaces. Our calculated power factor S"2σ/τ (with respect to an average unknown scattering time) of CoVSn is comparable to that of FeNbSb. A smaller lattice thermal conductivity can be expected from the smaller group velocities of acoustical modes compared to FeNbSb. Finally, overall, good thermoelectric performance for CoVSn can be expected by considering the electronic transport and lattice thermal conductivity.

Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

OpenAIRE

Megumi Sakurai; Taro Sato; Jiawei Xu; Soichi Sato; Tatsuya Fujino

2018-01-01

Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe....

Spectroscopy of deep doping levels in Cd{sub 0.99}Mn{sub 0.01}Te:Ga; Spektroskopia glebokich poziomow domieszkowych w Cd{sub 0.99}Mn{sub 0.01}Te:Ga

Energy Technology Data Exchange (ETDEWEB)

Szatkowski, J.; Placzek-Popko, E.; Sieranski, K. [Politechnika Wroclawska, Wroclaw (Poland); Bieg, B. [Wyzsza Szkola Morska, Szczecin (Poland)

1997-12-01

The investigation results of deep energy levels in Cd{sub 0.99}Mn{sub 0.01}Te (n-type) doped with gallium have been presented. Deep level transient spectroscopy (DLTS) measurements have been carried out in temperature range 80-420 K. The results show five types of electron traps. The activation energy of trapping levels and electron trapping cross-sections have been determined for observed traps. 2 refs, 3 figs, 1 tab.

Homogenous smooth sol gel films doped with organic compounds for nonlinear optics

Energy Technology Data Exchange (ETDEWEB)

Vasiliu, I.C. [INOE 2000 — National Institute for Optoelectronics, 409 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania); Ionita, I., E-mail: i_ionita@yahoo.com [UB — University of Bucharest, 405 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania); Matei, A. [INFLPR — National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania); Elisa, M.; Iordanescu, R.; Feraru, I.; Emandi, A. [INOE 2000 — National Institute for Optoelectronics, 409 Atomistilor Str., Magurele, Bucharest, RO 077125 (Romania)

2016-02-29

The demand for protection of various types of optical sensors from laser-beam pulses has resulted in the search for optical limiting devices that have the property of being transparent at low intensity of light (normal light), but no transparent towards high intensity (laser) light. Organic material with nonlinear optical (NLO) properties as reverse saturable absorption and two-photon absorption can be used for optical limiting with the advantage of a very fast response and self-activation. A promising approach in the fabrication of thin films by low cost/easy use deposition methods for second-order nonlinear optics is sol–gel technique. The present paper reports on the sol–gel synthesis of some pyrazolone derivative doped SiO{sub 2}–P{sub 2}O{sub 5} smooth and homogenous films (Root mean square roughness (Rq) = 1.1 nm) using as precursors tetraethylorthosilicate (TEOS) and phosphoric acid (H{sub 3}PO{sub 4}). The structure of the deposited azo-derivatives doped thin films was examined by Fourier transform infrared spectroscopy and atomic force microscopy, while their optical properties of the films by UV–VIS spectroscopy. The nonlinear optical efficiencies due to the interaction of the NLO-active chromophores with the inorganic matrix have a significant influence on the second harmonic generation capabilities that was measured using a femtosecond Ti:Sapphire laser. The properties of the films were investigated and correlated with the concentration of the organic dopant and the thermal treatment temperature. - Highlights: • We obtained pyrazolone derivative doped SiO{sub 2}–P{sub 2}O{sub 5} smooth and homogenous films. • The pyrazolone derivative presents SHG characteristics by itself. • Thin sol gel films doped with organic compounds with NLO properties. • Temperature of thermal treatment and aging time can improve NLO properties of films. • We found that 150 °C and 28 h aging time give the maximum performance in SHG response.

Evolution of magnetostructural transition and magnetocaloric effect with Al doping in MnCoGe1-xAlx compounds

KAUST Repository

Bao, Lifu; Hu, Fengxia; Wu, Rongrong; Wang, Jianping; Chen, Liming; Sun, Jirong; Shen, Baogen; Li, Lain-Jong; Zhang, Bei; Zhang, Xixiang

2014-01-01

The effect of Al doping in MnCoGe1-xAlx compounds has been investigated. The substitution of Al for Ge enhances Mn-Mn covalent bonding by shortening the distance of nearest Mn atom layers, and thus stabilizes the hexagonal structure. As a result, first-order magnetostructural transition between ferromagnetic martensite and paramagnetic austenite takes place for the optimized compositions (x = 0.01, 0.02). Accompanied with the magnetostructural transition, large magnetocaloric effect (MCE) is observed. More doping of Al(x = 0.03, 0.04) leads to the separation of magnetic and structural transitions and remarkable reduction of MCE. © 2014 IOP Publishing Ltd.

Evolution of magnetostructural transition and magnetocaloric effect with Al doping in MnCoGe1-xAlx compounds

KAUST Repository

Bao, Lifu

2014-01-03

The effect of Al doping in MnCoGe1-xAlx compounds has been investigated. The substitution of Al for Ge enhances Mn-Mn covalent bonding by shortening the distance of nearest Mn atom layers, and thus stabilizes the hexagonal structure. As a result, first-order magnetostructural transition between ferromagnetic martensite and paramagnetic austenite takes place for the optimized compositions (x = 0.01, 0.02). Accompanied with the magnetostructural transition, large magnetocaloric effect (MCE) is observed. More doping of Al(x = 0.03, 0.04) leads to the separation of magnetic and structural transitions and remarkable reduction of MCE. © 2014 IOP Publishing Ltd.

Thermal lens and all optical switching of new organometallic compound doped polyacrylamide gel

Science.gov (United States)

Badran, Hussain Ali

In this work thermal lens spectrometry (TLS) is applied to investigate the thermo-optical properties of new organometallic compound containing azomethine group, Dichloro bis [2-(2-hydroxybenzylideneamino)-5-methylphenyl] telluride platinum(II), doped polyacrylamide gel using transistor-transistor logic (TTL) modulated cw 532 nm laser beam as an excitation beam modulated at 10 Hz frequency and probe beam wavelength 635 nm at 14 mW. The technique is applied to determine the thermal diffusivities, ds/dT and the linear thermal expansion coefficient of the sample. All-optical switching effects with low background and high stability are demonstrated.

Optical and electrical properties of Zn{sub 1-x}Cd{sub x}O thin films

Energy Technology Data Exchange (ETDEWEB)

Joishy, Sumanth; Rajendra, B.V. [Manipal University, Department of Physics, Manipal Institute of Technology, Manipal (India)

2017-11-15

This report includes comprehensive studies on the influence of cadmium doping level of structure, surface morphology, optical and electrical properties of synthesized Zn{sub 1-x}Cd{sub x}O thin films by simple and inexpensive spray pyrolysis method under optimized deposition conditions using zinc acetate dihydrate and cadmium acetate dihydrate as precursors. All deposited films were polycrystalline in nature. The deposits were having 20-50% of the Cd content-shown mixture of hexagonal-cubic phases. However, with increasing Cd concentration only cubic phases were observed. The films have a fibrous structure change to the spherical nano-structure when doping level is more than 10% in the deposits. The composition of the Zn{sub x}Cd{sub 1-x}O-deposited films was confirmed by EDAX spectrum. Optical transmittance of deposits in the visible range was decreased with increasing Cd dopant. The change of energy band gap of Cd-doped ZnO films from 3.01 to 2.29 eV was observed. A systematic increase of the films n-type electrical conductivity was noticed due to increasing carrier concentration in the deposits except for 40% of Cd doping. (orig.)

Reassignment of oxygen-related defects in CdTe and CdSe

Energy Technology Data Exchange (ETDEWEB)

Bastin, Dirk

2015-05-22

This thesis reassigns the O{sub Te}-V{sub Cd} complex in CdTe and the O{sub Se}-V{sub Cd} complex in CdSe to a sulfur-dioxygen complex SO{sub 2}*, and the O{sub Cd} defect in CdSe to a V{sub Cd}H{sub 2} complex using Fourier transformed infrared absorption spectroscopy. The publications of the previous complexes were investigated by theoreticians who performed first-principle calculations of theses complexes. The theoreticians ruled out the assignments and proposed alternative defects, instead. The discrepancy between the experimentally obtained and theoretically proposed defects was the motivation of this work. Two local vibrational modes located at 1096.8 (ν{sub 1}) and 1108.3 cm{sup -1} (ν{sub 2}) previously assigned to an O{sub Te}-V{sub Cd} complex are detected in CdTe single crystals doped with CdSO{sub 4} powder. Five weaker additional absorption lines accompanying ν{sub 1} and ν{sub 2} could be detected. The relative intensities of the absorption lines match a sulfur-dioxygen complex SO{sub 2}* having two configurations labeled ν{sub 1} and ν{sub 2}. A binding energy difference of 0.5±0.1 meV between the two configurations and an energy barrier of 53±4 meV separating the two configurations are determined. Uniaxial stress applied to the crystal leads to a splitting of the absorption lines which corresponds to an orthorhombic and monoclinic symmetry for ν{sub 1} and ν{sub 2}, respectively. In virgin and oxygen-doped CdSe single crystals, three local vibrational modes located at 1094.1 (γ{sub 1}), 1107.5 (γ{sub 2}), and 1126.3 cm{sup -1} (γ{sub 3}) previously attributed to an O{sub Se}-V{sub Cd} complex could be observed. The signals are accompanied by five weaker additional absorption features in their vicinity. The additional absorption lines are identified as isotope satellites of a sulfur-dioxygen complex SO{sub 2}* having three configurations γ{sub 1}, γ{sub 2}, and γ{sub 3}. IR absorption measurements with uniaxial stress applied to the

The effect of excitons on CdTe solar cells

International Nuclear Information System (INIS)

Karazhanov, S. Zh.; Zhang, Y.; Mascarenhas, A.; Deb, S.

2000-01-01

Temperature and doping-level dependence of CdTe solar cells is investigated, taking into account the involvement of excitons on photocurrent transport. We show that the density of excitons in CdTe is comparable with that of minority carriers at doping levels ≥10 15 cm -3 . From the investigation of the dark-saturation current, we show that the product of electron and hole concentrations at equilibrium is several orders of magnitude more than the square of the intrinsic carrier concentration. With this assumption, we have studied the effect of excitons on CdTe solar cells, and the effect is negative. CdTe solar cell performance with excitons included agrees well with existing experimental results. (c) 2000 American Institute of Physics

Effect of the sulfur and fluorine concentration on physical properties of CdS films grown by chemical bath deposition

Directory of Open Access Journals (Sweden)

K.E. Nieto-Zepeda

Full Text Available Undoped and F-doped CdS thin films were grown on glass slides by chemical bath deposition using thiourea, cadmium acetate and ammonium fluoride as sulfur, cadmium, and fluorine sources, respectively. Undoped CdS films were deposited varying the concentration of thiourea. Once the optimal thiourea concentration was determined, based on the crystalline quality of the samples, this concentration was maintained and ammonium fluoride was added at different concentrations in order to explore the effect of the F nominal concentration on properties of CdS films. Undoped and F-doped CdS films were characterized by X-ray diffraction, UV–Vis, room temperature photoluminescence, and four probe resistivity measurements. Results showed highly transparent F-doped CdS films with strong PL and low resistivity were obtained. Keywords: CdS films, F-doped CdS films, Chemical bath deposition, Optical properties, Room temperature photoluminescence

Application of glass particles doped by Zn(+2) as an antimicrobial and atoxic compound in LLDPE and HDPE.

Science.gov (United States)

Santos, M F; Machado, C; Tachinski, C G; Júnior, J F; Piletti, R; Peterson, M; Fiori, M A

2014-06-01

This study demonstrates the potential application of glass particles doped with Zn(+2) (GZn) as an atoxic, antimicrobial additive when used in conjunction with high density polyethylene (HDPE) and linear low density polyethylene (LLDPE) polymers. Toxicity tests demonstrated that these modified glass particles were nontoxic to human cells, and atomic absorption analyses demonstrated the migration of ionic species in quantities less than 2.0ppm for both the HDPE/GZn and LLDPE/GZn compounds. Microbiological tests demonstrated the antimicrobial effect of the pure GZn compound as well as the polymeric HDPE/GZn and LLDPE/GZn compounds. In addition, at percentages of GZn higher than 2.00wt.% and at a time of 4h, the bactericidal performance is excellent and equal for both polymeric compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

CdTe and related compounds: physics, defects, hetero- and nano-structures, crystal growth, surfaces and applications

CERN Document Server

Triboulet, Robert

Almost thirty years after the remarkable monograph of K. Zanio and the numerous conferences and articles dedicated since that time to CdTe and CdZnTe, after all the significant progresses in that field and the increasing interest in these materials for several extremely attractive industrial applications, such as nuclear detectors and solar cells, the edition of a new enriched and updated monograph dedicated to these two very topical II-VI semiconductor compounds, covering all their most prominent, modern and fundamental aspects, seemed very relevant and useful.

Antimony doped cadmium selenium nanobelts with enhanced electrical and optoelectrical properties

Energy Technology Data Exchange (ETDEWEB)

Zhang, Lijie [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Yu, Hongfei; Cao, Wei; Dong, Youqing; Zou, Chao; Yang, Yun [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Huang, Shaoming, E-mail: smhuang@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou 325027 (China); Dai, Ning [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Zhu, Da-Ming, E-mail: ZhuD@umkc.edu [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); University of Missouri-Kansas City, Kansas City, MO 64110 (United States)

2014-07-01

Intrinsic and Sb-doped CdSe nanobelts (NBs) were synthesized via a thermal evaporation technique. The electrical transport properties of field effect transistors (FETs) fabricated using the NBs were investigated. The results indicate that the Sb-doped NBs behave as n-type semiconductors with improved electrical conductivity (10⁻¹ to 100 S/cm) compared with the intrinsic CdSe. Photodetectors made of single NB were also fabricated and investigated. The results show that Sb-doped NB photodetectors exhibit much higher responsivity (1.5 × 10⁴ A/W) and external quantum efficiency (1.2 × 10⁵) but lower on/off current ratio (~253) and longer response time (≤40 ms). Furthermore, both electrical transport and optoelectrical properties of the as-synthesized CdSe NBs can be tuned by changing the doping concentration. The results indicate that the as-synthesized NBs are excellent building blocks for constructing electronic and optoelectronic devices.

[Zn(NH3)4][PtCl6] and [Cd(NH3)4][PtCl6] as precursors for intermetallic compounds PtZn and PtCd

International Nuclear Information System (INIS)

Zadesenets, A.V.; Venediktov, A.B.; Shubin, Yu.V.; Korenev, S.V.

2007-01-01

Double complex salts (tetraamminezinc and tetraamminecadmium hexachloroplatinates) have been synthesized. Their thermal properties have been studied, as well as the products of their degradation in hydrogen and helium atmospheres. Optimal thermolysis schedules have been determined. Thermolysis under hydrogen yields intermetallic compounds PtZn and PtCd [ru

The behaviour of doped elements in tungsten sintering

International Nuclear Information System (INIS)

Scheiner, L.

1975-01-01

The lecture deals with the occurrence of bubbles in the sintering of doped tungsten. The doping of tungsten normally takes place by the addition of K, Al and Si compounds. A part of the doping substances disappears with sintering which can easily be proved by chemical analyses. In the process described here, the evaporation is non-destructively observed during sintering with an absorption spectrometer. Temperature, absorption slope and sintering resistance are recorded. The evaluation of the absorption curves gives a diffusion equation. The discussion of the curves resulted so far in that a doped substance compound sets free the single elements of the compound at high temperature. Aluminium and silicon diffuse out. In the case of aluminium, the activation energy can be determined. (GSC/LH) [de

Phase transitions and doping in semiconductor nanocrystals

Science.gov (United States)

Sahu, Ayaskanta

impurities (or doping) allows further control over the electrical and optical properties of nanocrystals. However, while impurity doping in bulk semiconductors is now routine, doping of nanocrystals remains challenging. In particular, evidence for electronic doping, in which additional electrical carriers are introduced into the nanocrystals, has been very limited. Here, we adopt a new approach to electronic doping of nanocrystals. We utilize a partial cation exchange to introduce silver impurities into cadmium selenide (CdSe) and lead selenide (PbSe) nanocrystals. Results indicate that the silver-doped CdSe nanocrystals show a significant increase in fluorescence intensity, as compared to pure CdSe nanocrystals. We also observe a switching from n- to p-type doping in the silver-doped CdSe nanocrystals with increased silver amounts. Moreover, the silver-doping results in a change in the conductance of both PbSe and CdSe nanocrystals and the magnitude of this change depends on the amount of silver incorporated into the nanocrystals. In the bulk, silver chalcogenides (Ag2E, E=S, Se, and Te) possess a wide array of intriguing properties, including superionic conductivity. In addition, they undergo a reversible temperature-dependent phase transition which induces significant changes in their electronic and ionic properties. While most of these properties have been examined extensively in bulk, very few studies have been conducted at the nanoscale. We have recently developed a versatile synthesis that yields colloidal silver chalcogenide nanocrystals. Here, we study the size dependence of their phase-transition temperatures. We utilize differential scanning calorimetry and in-situ X-ray diffraction analyses to observe the phase transition in nanocrystal assemblies. We observe a significant deviation from the bulk alpha (low-temperature) to beta (high-temperature) phase-transition temperature when we reduce their size to a few nanometers. Hence, these nanocrystals provide great

Organic Light-Emitting Diodes with Magnesium Doped CuPc as an Efficient Electron Injection Layer

International Nuclear Information System (INIS)

Jun-Song, Cao; Min, Guan; Guo-Hua, Cao; Yi-Ping, Zeng; Jin-Min, Li; Da-Shan, Qin

2008-01-01

Bright organic electroluminescent devices are developed using a metal-doped organic layer intervening between the cathode and the emitting layer. The typical device structure is a glass substrate/indium-tin oxide (ITO)/copper phthalocyanine(CuPc)/N,N-bis-(1-naphthl)-diphenyl-1, 1'-biphenyl-4,4'-diamine (NPB)/Tris(8-quinolinolato) alu-minum(Alq 3 )/Mg-doped CuPc/Ag. At a driving voltage of 11 V, the device with a layer of Mg-doped CuPc (1:2 in weight) shows a brightness of 4312 cd/m 2 and a current efficiency of 2.52 cd/A, while the reference device exhibits 514 cd/m 2 and 1.25 cd/A

Magnetic hyperfine field in Tb Zn compound measured by PAC spectroscopy using {sup 111}Cd and {sup 140}Ce

Energy Technology Data Exchange (ETDEWEB)

Bosch-Santos, B.; Cabrera-Pasca, G.A.; Carbonari, A.W.; Costa, M.S.; Saxena, R.N., E-mail: brianna@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The ferromagnetic compound Tb Zn has been investigated by perturbed {gamma}-{gamma} angular correlation (PAC) spectroscopy using {sup 111}In{yields}{sup 111}Cd (t{sub 1/2} = 85 ns) and {sup 140}La{yields}{sup 140}Ce (t{sub 1/2} = 3,4 ns) as probe nuclei. Measurements were carried out in the temperature range of 10 - 295K for the {sup 111}Cd probe and below Curie temperature (T{sub C}) for the {sup 140}Ce probe. The study of magnetic properties of rare earth (R) and zinc compounds of the type RZn is interesting because Zn ion is a closed shell atom and the rare earth elements present a localized magnetism associated with 4f electrons, which do not participate in chemical bonds. Therefore, the magnetic properties of these compounds are only originated from the 4f electrons of rare earth. Furthermore, the compounds exhibit the highly symmetric cubic structure of the CsCl prototype and have a Curie temperature of TbZn is T{sub C} {approx} 204 K. (author)

Crystal structure and electrical conduction of the new organic-inorganic compound (CH2)2(NH3)2CdI4

Science.gov (United States)

Zhang, Liuqi; Wang, Jilin; Han, Feifei; Mo, Shuyi; Long, Fei; Gao, Yihua

2018-03-01

The new organic-inorganic compound (CH2)2(NH3)2CdI4 was prepared by slow evaporation method using a mixture solution of CdI2 and ethylenediamine iodide (EDAI) in the γ-butyrolactone (GBL). The synthesized compound was further characterized by single crystal diffraction, Infrared (IR) and Raman spectroscopy, energy dispersive spectrometer (EDS), X-Ray photoelectron spectroscopy (XPS) and thermogravimetric analysis. The relaxation behavior and conductivity mechanism of (CH2)2(NH3)2CdI4 was studied by the electrical impedance spectroscopy. The results indicated that (CH2)2(NH3)2CdI4 had a monoclinic structure with space group P21/c at room temperature. The complex impedance plotted as semicircle arcs and the proposed electrical equivalent circuit was to interpret the impedance behavior at different temperatures. The electrical equivalent circuit was made of a parallel combination of resistance (R) and fractal capacitance (CPE). Furthermore, the alternating current conductivity of the sample obeyed the Jonscher's law: σf =σdc + Afs and the conduction could be attributed to the correlated barrier hopping (CBH) model.

Study of the CdX-B2X3-X (X=S, Se), CdTe-B-Te systems

International Nuclear Information System (INIS)

Odin, I.N.; Grin'ko, V.V.; Safronov, E.V.; Kozlovskij, V.F.

2001-01-01

Liquidus surfaces of the CdX-B 2 X 3 -X (X=S, Se), CdTe-B-Te systems are plotted for the first time. It is shown that in equilibrium solid solutions on the basis of ternary Cd 2 B 2 X 5 compounds and binary B 2 X 3 , CdX, BS 2 compounds take part with liquid phases. p gen -T and T-x projects of p-T-x phase diagram of B-S (59-100 at. % S), B-Se (59-100 at. % Se), B-Te systems are plotted . B 2 X 3 , BS 2 compounds are formed in that regions of compositions of B-X systems . In the B-Te system compounds are not formed. Ternary compounds are not formed in the CdTe-B-Te system [ru

Neutron transmutation doping of gallium arsenide

International Nuclear Information System (INIS)

Alexiev, D.

1987-12-01

Neutron transmutation doping (NTD) was studied as a means of compensating p-type Cd-doped GaAs. By introducing specific donor concentrations, the net acceptor level was measured and showed a progressive reduction. The NTD constant K = 0.32 donor atoms.cm 3 per cm 2 was also measured. Radiation damage caused by neutron bombardment was annealed and no additional traps were generated

Thermal stability of substitutional ag in CdTe

NARCIS (Netherlands)

Jahn, SG; Hofsass, H; Restle, M; Ronning, C; Quintel, H; BharuthRam, K; Wahl, U

The thermal stability of substitutional Ag in CdTe was deduced from lattice location measurements at different temperatures. Substitutional Ag probe atoms were generated via transmutation doping from radioactive Cd isotopes. The lattice sites of Ag isotopes were determined by measuring the

Role of polymer matrix on photo-sensitivity of CdSe polymer nanocomposites

Science.gov (United States)

Kaur, Ramneek; Tripathi, S. K.

2018-04-01

This paper reports the effect of three different polymer matrices (PVP, PMMA and PVK) and Ag doping on the photo-sensitivity of CdSe polymer nanocomposites. The results reveal that the photoconductivity is high for linear chain polymer nanocomposites as compared to aromatic ones with decreasing trend as: CdSe-PMMA > CdSe-PVP > CdSe-PVK. The large substituents or branches along the polymer backbone hinder the stacking sequences in CdSe-PVK nanocomposites resulting in lowest photoconductivity. On contrary, CdSe-PVK nanocomposite exhibit highest photosensitivity. The reason behind it is the low value of dark conductivity in CdSe-PVK nanocomposite and photoconductive PVK matrix. With Ag doping, no considerable effect on the value of photosensitivity has been observed. The obtained results indicate that the photo-conducting properties of these polymer nanocomposites can be tuned by using different polymer matrices.

Microstructural and thermoelectric properties of p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} and n-type SbI{sub 3}-doped Bi{sub 2}Te{sub 2.85}Se{sub 0.15} compounds

Energy Technology Data Exchange (ETDEWEB)

Seo, J; Park, K; Lee, C; Kim, J

1997-07-01

The p-type Te-doped Bi{sub 0.5}Sb{sub 1.5}Te{sub 3} and n-type SbI{sub 3}-doped Bi{sub 2}Te{sub 2.85}Se{sub 0.15} thermoelectric compounds were fabricated by hot pressing in the temperature range of 380 to 440 C under 200 MPa in Ar. Both the compounds were highly dense and showed high crystalline quality. The grains of the compounds were preferentially oriented and contained many dislocations through the hot pressing. The fracture path followed the transgranular cleavage planes, which are perpendicular to the c-axis. In addition, with increasing the pressing temperature, the figure of merit was increased. The highest values of figure of merit for the p- and n-type compounds, which were obtained at 420 C, were 2.69 x 10{sup {minus}3}/K and 2.35 x 10{sup {minus}3}/K, respectively.

Efficient non-doped phosphorescent orange, blue and white organic light-emitting devices

Science.gov (United States)

Yin, Yongming; Yu, Jing; Cao, Hongtao; Zhang, Letian; Sun, Haizhu; Xie, Wenfa

2014-10-01

Efficient phosphorescent orange, blue and white organic light-emitting devices (OLEDs) with non-doped emissive layers were successfully fabricated. Conventional blue phosphorescent emitters bis [4,6-di-fluorophenyl]-pyridinato-N,C2'] picolinate (Firpic) and Bis(2,4-difluorophenylpyridinato) (Fir6) were adopted to fabricate non-doped blue OLEDs, which exhibited maximum current efficiency of 7.6 and 4.6 cd/A for Firpic and Fir6 based devices, respectively. Non-doped orange OLED was fabricated utilizing the newly reported phosphorescent material iridium (III) (pbi)2Ir(biq), of which manifested maximum current and power efficiency of 8.2 cd/A and 7.8 lm/W. The non-doped white OLEDs were achieved by simply combining Firpic or Fir6 with a 2-nm (pbi)2Ir(biq). The maximum current and power efficiency of the Firpic and (pbi)2Ir(biq) based white OLED were 14.8 cd/A and 17.9 lm/W.

Se-Se isoelectronic centers in high purity CdTe

Energy Technology Data Exchange (ETDEWEB)

Najjar, Rita; Andre, Regis; Mariette, Henri [CEA-CNRS, Nanophysique et Semiconducteurs, Institut Neel, 25 rue des martyrs, 38042 Grenoble (France); Golnik, Andrzej; Kossacki, Piotr; Gaj, Jan A. [Institute of Experimental Physics, University of Warsaw, Hoza 69, 00-681 Warsaw (Poland)

2010-06-15

We evidence zero-dimensional exciton states trapped on isoelectronic Se centers in CdTe quantum wells, {delta}-doped with Se. Thanks to special precautions taken to have very high purity CdTe heterostructures, it is possible to observe, in photoluminescence spectra, sharp discrete lines arising from individual centers related to the Se doping. These emission lines appear at about 40 meV below the CdTe band gap energy. The most prominent lines are attributed to the recombination of excitons bound to nearest-neighbor selenium pairs in a tetrahedral CdTe environment. This assignment is confirmed by a common linear polarization direction of the emitted light, parallel to <110>. These excitons localized on individual isoelectronic traps are good candidates as single photon emitters (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Synthesis of Cd doped ZnO/CNT nanocomposite by using microwave method: Photocatalytic behavior, adsorption and kinetic study

Directory of Open Access Journals (Sweden)

Mohammad Hossein Ahmadi Azqhandi

Full Text Available The Cd-doped ZnO/CNT nanocomposites (Cd@ZnO/CNT-NCs were synthesized by the microwave assisted hydrothermal method. The as-synthesized Cd@ZnO/CNT-NCs was characterized in detail in term of their structural, morphological, chemical and optical properties using XRD; SEM, FE-TEM, BET and UV–Vis methods. The band gap energy measurements confirmed that the addition of Cd ions causes a decrease in the band gap energy of the nanocomposites. The photocatalytic properties of the synthesized nanocomposites were investigated by the measurements of methyl orange (MO degradation under UV irradiation.The equilibrium adsorption data of all three nanocomposites (i.e. ZnO/CNT, CZC-1, CZC-0.25 were analyzed by Langmuir and Freundlich isotherm models, respectively. The best fit to the data was obtained from the Langmuir model. The decrease in MO dye concentration was examined by UV–Visible spectroscopy at different time intervals under ultraviolet light irradiation, until the dye was completely degraded to colorless end product. Rapid MO dye decomposition was observed with a degradation rate of ∼93, 70 and 44% on the CZC-1, CZC-0.25 and ZnO/CNT within the initial 110 min, respectively. The fast degradation rate and high degradation efficiency of CZC-1 and CZC-0.25 is attributed to the porous nature, large specific surface area (162.5 and 136.1 m2 g−1, narrow pore size distribution (7.46 and 12.98 nm evaluated from N2 adsorption-desorption isotherms analysis and excellent electron accepting features of the engineered porous Cd@ZnO/CNT-NCs. The kinetic results revealed that the degradation rate of MO on the CZC-1 (i.e. Cd0.5Zn0.5O/CNT and CZC-0.25 (i.e. Cd0.25Zn0.75O/CNT is approximately 2- and 4-folds larger than the CNT/ZnO that can be explained by the replacement of Cd ions in the ZnO structure. The degradation of the model dyes was observed to follow pseudo first order degradation kinetics. Keywords: Adsorption, CNTs, CNT/ZnO nanocomposites, CNT/ZnO:Cd

Microscopic theory of cation exchange in CdSe nanocrystals.

Science.gov (United States)

Ott, Florian D; Spiegel, Leo L; Norris, David J; Erwin, Steven C

2014-10-10

Although poorly understood, cation-exchange reactions are increasingly used to dope or transform colloidal semiconductor nanocrystals (quantum dots). We use density-functional theory and kinetic Monte Carlo simulations to develop a microscopic theory that explains structural, optical, and electronic changes observed experimentally in Ag-cation-exchanged CdSe nanocrystals. We find that Coulomb interactions, both between ionized impurities and with the polarized nanocrystal surface, play a key role in cation exchange. Our theory also resolves several experimental puzzles related to photoluminescence and electrical behavior in CdSe nanocrystals doped with Ag.

Optical, structural and surface characterization of ultrasonically sprayed CdO:F films

International Nuclear Information System (INIS)

Akyuz, I.; Kose, S.; Ketenci, E.; Bilgin, V.; Atay, F.

2011-01-01

Research highlights: → The effect of F doping on the optical, structural and surface properties of ultrasonically sprayed CdO films has been investigated. F doping affected each of these properties. → The low cost of the production system is an advantage for potential applications of these films. CF4 film caused the transmittance values to increase which is a desired development for transparent conducting oxide industry. → Low reflectance value of CF2 film makes this sample a promising material for anti-reflection coatings. → F doping has found to be an alternative solution to increase the narrow band gap of CdO films. This is an other development of CdO:F films for optoelectronic and photovoltaic solar cell applications. → Rough samples may be an alternative in single-junction μc-Si solar cells having superstrate configuration. When we take into account the refractive index and rough surface of the samples, rough interface between a low refractive index material (CdO:F, n ∼ 1.6) and a high refractive index material (for Si n ∼ 3.7) results in reduced reflection due to gradual refractive index matching. In order to increase this effect high rms roughness (R q ) values needed. Also this will allow light trapping into Si layer and cause back and forth scattering at the interfaces increasing the optical path within the Si layer. - Abstract: In this work, we report the effect of F doping on some physical properties of CdO films. Ultrasonic spray pyrolysis technique has been used to obtain the films. Thicknesses, refractive indices and extinction coefficients of the films have been determined by spectroscopic ellipsometry technique using Cauchy-Urbach model for fitting. Transmission and reflectance spectra have been taken by UV spectrophotometer, and band gap values have been determined by optical method. X-ray diffraction patterns have been used to study the structural properties such as crystallinity level, texture coefficient, crystallite size and

Effect of intermixing at CdS/CdTe interface on defect properties

Energy Technology Data Exchange (ETDEWEB)

Park, Ji-Sang, E-mail: jspark@anl.gov; Yang, Ji-Hui; Barnes, Teresa [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States); Wei, Su-Huai, E-mail: suhuaiwei@csrc.ac.cn [Beijing Computational Science Research Center, Beijing 100094 (China)

2016-07-25

We investigated the stability and electronic properties of defects in CdTe{sub 1−x}S{sub x} that can be formed at the CdS/CdTe interface. As the anions mix at the interface, the defect properties are significantly affected, especially those defects centered at cation sites like Cd vacancy, V{sub Cd}, and Te on Cd antisite, Te{sub Cd}, because the environment surrounding the defect sites can have different configurations. We show that at a given composition, the transition energy levels of V{sub Cd} and Te{sub Cd} become close to the valence band maximum when the defect has more S atoms in their local environment, thus improving the device performance. Such beneficial role is also found at the grain boundaries when the Te atom is replaced by S in the Te-Te wrong bonds, reducing the energy of the grain boundary level. On the other hand, the transition levels with respect to the valence band edge of CdTe{sub 1−x}S{sub x} increases with the S concentration as the valence band edge decreases with the S concentration, resulting in the reduced p-type doping efficiency.

Study of doping non-PMMA polymer fibre canes with UV photosensitive compounds

DEFF Research Database (Denmark)

Hassan, Hafeez Ul; Fasano, Andrea; Janting, Jakob

2016-01-01

and hollow-core TOPAS canes were doped with a solution of dopants in acetone/methanol and hexane/methanol, respectively. Doping time, solvent mixture concentration and doping temperature were optimised. A long and stepwise drying process was applied to the doped canes to ensure complete solvent removal...

Electrodeposition of ZnO-doped films as window layer for Cd-free CIGS-based solar cells

Science.gov (United States)

Tsin, Fabien; Vénérosy, Amélie; Hildebrandt, Thibaud; Hariskos, Dimitrios; Naghavi, Negar; Lincot, Daniel; Rousset, Jean

2016-02-01

The Cu(In,Ga)Se2 (CIGS) thin film solar cell technology has made a steady progress within the last decade reaching efficiency up to 22.3% on laboratory scale, thus overpassing the highest efficiency for polycrystalline silicon solar cells. High efficiency CIGS modules employ a so-called buffer layer of cadmium sulfide CdS deposited by Chemical Bath Deposition (CBD), which presence and Cd-containing waste present some environmental concerns. A second potential bottleneck for CIGS technology is its window layer made of i-ZnO/ZnO:Al, which is deposited by sputtering requiring expensive vacuum equipment. A non-vacuum deposition of transparent conductive oxide (TCO) relying on simpler equipment with lower investment costs will be more economically attractive, and could increase competitiveness of CIGS-based modules with the mainstream silicon-based technologies. In the frame of Novazolar project, we have developed a low-cost aqueous solution photo assisted electrodeposition process of the ZnO-based window layer for high efficiency CIGS-based solar cells. The window layer deposition have been first optimized on classical CdS buffer layer leading to cells with efficiencies similar to those measured with the sputtered references on the same absorber (15%). The the optimized ZnO doped layer has been adapted to cadmium free devices where the CdS is replaced by chemical bath deposited zinc oxysulfide Zn(S,O) buffer layer. The effect of different growth parameters has been studied on CBD-Zn(S,O)-plated co-evaporated Cu(In,Ga)Se2 substrates provided by the Zentrum für Sonnenenergie-und Wasserstoff-Forschung (ZSW). This optimization of the electrodeposition of ZnO:Cl on CIGS/Zn(S,O) stacks led to record efficiency of 14%, while the reference cell with a sputtered (Zn,Mg)O/ZnO:Al window layer has an efficiency of 15.2%.

Superconducting Cd and Ca doped 123 phase in Cdo.8Ba2(Y0.7Ca0.4) Cu3.5Oy

International Nuclear Information System (INIS)

Balchev, N.; Kovachev, V; THOMAS, J.; BIEGER, W.; Konstantinov, K.; Kunev, B.

1999-01-01

A new Cd-containing superconductor with nominal composition of Cd 0.8 Ba 2 (Y 0.7 Ca 0.4 ) Cu 3.5 O y and T c = 80 K was synthesized and investigated. The obtained XRD pattern shows that the dominating phase is an orthorhombic 123. It was shown that the presence of Cd and Ca facilitates the 123 phase formation. The results of the EDX analysis on SEM and TEM have shown that the distribution of the Cd and Ca in the samples is inhomogeneous. The two elements enter the 123 phase in most of the investigated crystals and form a new Cd-Ba-Y-Ca-Cu-O superconducting compound

Electronic and optical properties of the LiCdX (X = N, P, As and Sb) filled-tetrahedral compounds with the Tran–Blaha modified Becke–Johnson density functional

International Nuclear Information System (INIS)

Bouhemadou, A.; Bin-Omran, S.; Allali, D.; Al-Otaibi, S.M.; Khenata, R.; Al-Douri, Y.; Chegaar, M.; Reshak, A.H.

2015-01-01

Highlights: • Electronic and optical properties of the LiCdX compounds have been predicted. • Tran–Blaha-modified Becke–Johnson functional significantly improves the band gap. • We predict a direct band gap in all of the considered LiCdX compounds. • Origin of the peaks in the optical spectra is determined. - Abstract: The structural, electronic and optical properties of the LiCdN, LiCdP, LiCdAs and LiCdSb filled-tetrahedral compounds have been explored from first-principles. The calculated structural parameters are consistent with the available experimental results. Since DFT with the common LDA and GGA underestimates the band gap, we use a new developed functional able to accurately describe the electronic structure of semiconductors, namely the Tran–Blaha-modified Becke–Johnson potential. The four investigated compounds demonstrate semiconducting behavior with direct band gap ranging from about 0.32 to 1.65 eV. The charge-carrier effective masses are evaluated at the topmost valence band and at the bottommost conduction band. The evolution of the value and nature of the energy band gap under pressure effect is also investigated. The frequency-dependent complex dielectric function and some macroscopic optical constants are estimated. The microscopic origins of the structures in the optical spectra are determined in terms of the calculated energy band structures

Electronic and optical properties of the LiCdX (X = N, P, As and Sb) filled-tetrahedral compounds with the Tran–Blaha modified Becke–Johnson density functional

Energy Technology Data Exchange (ETDEWEB)

Bouhemadou, A., E-mail: a_bouhemadou@yahoo.fr [Laboratory for Developing New Materials and their Characterization, University of Setif 1, Setif 19000 (Algeria); Bin-Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Department of Physics, Faculty of Science & Humanitarian Studies, Salman Bin Abdalaziz University, Alkharj 11942 (Saudi Arabia); Allali, D. [Laboratory for Developing New Materials and their Characterization, University of Setif 1, Setif 19000 (Algeria); Al-Otaibi, S.M. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Khenata, R. [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Al-Douri, Y. [Institute of Nano Electronic Engineering, Universiti Malaysia Perlis, Kangar, Perlis 01000 (Malaysia); Chegaar, M. [Department of Physics, Faculty of Science, University of Setif 1, Setif 19000 (Algeria); Reshak, A.H. [New Technologies-Research Center, University of West Bohemia, Univerzitni 8, Pilson 306 14 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, Kangar, Perlis 01007 (Malaysia)

2015-04-15

Highlights: • Electronic and optical properties of the LiCdX compounds have been predicted. • Tran–Blaha-modified Becke–Johnson functional significantly improves the band gap. • We predict a direct band gap in all of the considered LiCdX compounds. • Origin of the peaks in the optical spectra is determined. - Abstract: The structural, electronic and optical properties of the LiCdN, LiCdP, LiCdAs and LiCdSb filled-tetrahedral compounds have been explored from first-principles. The calculated structural parameters are consistent with the available experimental results. Since DFT with the common LDA and GGA underestimates the band gap, we use a new developed functional able to accurately describe the electronic structure of semiconductors, namely the Tran–Blaha-modified Becke–Johnson potential. The four investigated compounds demonstrate semiconducting behavior with direct band gap ranging from about 0.32 to 1.65 eV. The charge-carrier effective masses are evaluated at the topmost valence band and at the bottommost conduction band. The evolution of the value and nature of the energy band gap under pressure effect is also investigated. The frequency-dependent complex dielectric function and some macroscopic optical constants are estimated. The microscopic origins of the structures in the optical spectra are determined in terms of the calculated energy band structures.

Thermoluminescence in some copper-doped compounds

International Nuclear Information System (INIS)

Patil, R.R.; Moharil, S.V.; Dhopte, S.M.; Muthal, P.L.; Kondawar, V.K.

2003-01-01

Thermoluminescence (TL) in various Cu + -doped materials is studied. A good correlation between the presence of copper in the Cu + form and TL sensitivity is observed. Correlation between TL emission spectra and photoluminescence suggests that Cu + acts as the emission center in the TL process. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Influence of dopant concentration on the electrical properties of the CdSe-PMMA nanocomposite

Energy Technology Data Exchange (ETDEWEB)

Kaur, Ramneek; Tripathi, S. K., E-mail: surya@pu.ac.in, E-mail: surya-tr@yahoo.com [Department of Physics, Center of Advanced Study in Physics, Panjab University, Chandigarh-160 014 (India)

2016-05-06

This paper reports the synthesis and electrical characterization of CdSe-PMMA nanocomposite. CdSe-PMMA nanocomposite has been prepared by ex-situ technique through chemical route. The influence of three different Ag doping concentrations on the electrical properties has been studied in the temperature range ∼ 303-353 K. Transmission electron micrograph reveals the spherical morphology of the CdSe nanoparticles and their proper dispersion in the PMMA matrix. The electrical conduction of the polymer nanocomposites is through thermally activated process with single activation energy. With Ag doping, initially the activation energy increases upto 0.2 % Ag doping concentration but with further increase in Ag concentration, it decreases. This behavior has been discussed on the basis of randomly oriented grain boundaries and defect states. Thus, the results indicate that the transport properties of the polymer nanocomposites can be tailored by controlled doping concentration.

Influence of dopant concentration on the electrical properties of the CdSe-PMMA nanocomposite

International Nuclear Information System (INIS)

Kaur, Ramneek; Tripathi, S. K.

2016-01-01

This paper reports the synthesis and electrical characterization of CdSe-PMMA nanocomposite. CdSe-PMMA nanocomposite has been prepared by ex-situ technique through chemical route. The influence of three different Ag doping concentrations on the electrical properties has been studied in the temperature range ∼ 303-353 K. Transmission electron micrograph reveals the spherical morphology of the CdSe nanoparticles and their proper dispersion in the PMMA matrix. The electrical conduction of the polymer nanocomposites is through thermally activated process with single activation energy. With Ag doping, initially the activation energy increases upto 0.2 % Ag doping concentration but with further increase in Ag concentration, it decreases. This behavior has been discussed on the basis of randomly oriented grain boundaries and defect states. Thus, the results indicate that the transport properties of the polymer nanocomposites can be tailored by controlled doping concentration.

Synthesis, characterization and charge transport mechanism of CdZnO nanorods

International Nuclear Information System (INIS)

Mahmoud, Waleed E.; Al-Ghamdi, A.A.; El-Tantawy, F.; Al-Heniti, S.

2009-01-01

ZnO and Cd-doped ZnO nanostructures were prepared by new facile method at 80 deg. C. XRD measurement indicated that both samples had typical hexagonal wurtzite structures. Transmission electron microscopy (TEM) measurement shows that rod-like crystals have been formed. EDX measurement confirms the incorporation of the cadmium ion into the crystalline lattice of ZnO and indicated that cadmium ions uniformly distributed on the surface of the rods. The doping with cadmium ions has a great influence on the optical properties of the ZnO. The electrical measurements of Cd-doped ZnO nanorod were measured. The current-voltage (I-V) characteristic curve revealed that the charge transport above 4 V is mainly non-linear due to grain boundary contribution. The complex impedance spectroscopy was confirmed that the grain boundary effect controls the charge transport mechanism through CdZnO ceramic material.

The effect of cadmium doping of Pbsub(1-x)Snsub(x)Te crystals and thin layers on the electrical properties of the system

International Nuclear Information System (INIS)

Silberg, E.

1982-06-01

In the present work the doping characteristics and electrical properties of Cd-doped bulk crystals (as-grown and annealed) and LPE layers of Pbsub(1-x)Snsub(x)Te, 0<=x<=0.25, were studied using Hall effect, resistivity and Cd-solubility measurements. The bulk crystals were doped by Cd-diffusion in a two-temperature-zone furnace and the LPE layers by adding Cd to the growth solution. Cd doping was used to produce uniform n-type LPE layers of Pbsub(1-x)Snsub(x)Te and the process proved to be a controllable and reproducible method for the production of good quality material with low electron concentration and high electron mobility. These qualities are very important in obtaining improved electrooptical devices. (H.K.)

Compton profiles and band structure calculations of CdS and CdTe

International Nuclear Information System (INIS)

Heda, N.L.; Mathur, S.; Ahuja, B.L.; Sharma, B.K.

2007-01-01

In this paper we present the isotropic Compton profiles of zinc-blende CdS and CdTe measured at an intermediate resolution of 0.39 a.u. using our 20 Ci 137 Cs Compton spectrometer. The electronic band structure calculations for both the zinc-blende structure compounds and also wurtzite CdS have been undertaken using various schemes of ab-initio linear combination of atomic orbitals calculations implemented in CRYSTAL03 code. The band structure and Mulliken's populations are reported using density functional scheme. In case of wurtzite CdS, our theoretical anisotropies in directional Compton profiles are compared with available experimental data. In case of both the zinc-blende compounds, the isotropic experimental profiles are found to be in better agreement with the present Hartree-Fock calculations. A study of the equal-valence-electron-density experimental profiles of zinc-blende CdS and CdTe shows that the CdS is more ionic than CdTe. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Reassignment of oxygen-related defects in CdTe and CdSe

International Nuclear Information System (INIS)

Bastin, Dirk

2015-01-01

This thesis reassigns the O_T_e-V_C_d complex in CdTe and the O_S_e-V_C_d complex in CdSe to a sulfur-dioxygen complex SO_2*, and the O_C_d defect in CdSe to a V_C_dH_2 complex using Fourier transformed infrared absorption spectroscopy. The publications of the previous complexes were investigated by theoreticians who performed first-principle calculations of theses complexes. The theoreticians ruled out the assignments and proposed alternative defects, instead. The discrepancy between the experimentally obtained and theoretically proposed defects was the motivation of this work. Two local vibrational modes located at 1096.8 (ν_1) and 1108.3 cm"-"1 (ν_2) previously assigned to an O_T_e-V_C_d complex are detected in CdTe single crystals doped with CdSO_4 powder. Five weaker additional absorption lines accompanying ν_1 and ν_2 could be detected. The relative intensities of the absorption lines match a sulfur-dioxygen complex SO_2* having two configurations labeled ν_1 and ν_2. A binding energy difference of 0.5±0.1 meV between the two configurations and an energy barrier of 53±4 meV separating the two configurations are determined. Uniaxial stress applied to the crystal leads to a splitting of the absorption lines which corresponds to an orthorhombic and monoclinic symmetry for ν_1 and ν_2, respectively. In virgin and oxygen-doped CdSe single crystals, three local vibrational modes located at 1094.1 (γ_1), 1107.5 (γ_2), and 1126.3 cm"-"1 (γ_3) previously attributed to an O_S_e-V_C_d complex could be observed. The signals are accompanied by five weaker additional absorption features in their vicinity. The additional absorption lines are identified as isotope satellites of a sulfur-dioxygen complex SO_2* having three configurations γ_1, γ_2, and γ_3. IR absorption measurements with uniaxial stress applied to the CdSe crystal yield a monoclinic C_1_h symmetry for γ_1 and γ_2. The SO_2* complex is stable up to 600 C. This thesis assigns the ν-lines in

Preparation of p-type NiO films by reactive sputtering and their application to CdTe solar cells

Science.gov (United States)

Ishikawa, Ryousuke; Furuya, Yasuaki; Araki, Ryouichi; Nomoto, Takahiro; Ogawa, Yohei; Hosono, Aikyo; Okamoto, Tamotsu; Tsuboi, Nozomu

2016-02-01

Transparent p-type NiO films were prepared by reactive sputtering using the facing-target system under Ar-diluted O2 gas at Tsub of 30 and 200 °C. The increasing intensity of dominant X-ray diffraction (XRD) peaks indicates improvements in the crystallinity of NiO films upon Cu doping. In spite of the crystallographic and optical changes after Cu-doping, the electrical properties of Cu-doped NiO films were slightly improved. Upon Ag-doping at 30 °C under low O2 concentration, on the other hand, the intensity of the dominant (111) XRD peaks was suppressed and p-type conductivity increased from ˜10-3 to ˜10-1 S cm-1. Finally, our Ag-doped NiO films were applied as the back contact of CdTe solar cells. CdTe solar cells with a glass/ITO/CdS/CdTe/NiO structure exhibited an efficiency of 6.4%, suggesting the high potential of using p-type NiO for the back-contact film in thin-film solar cells.

Structural features of AgCaCdMg2(PO4)3 and AgCd2Mg2(PO4)3, two new compounds with the alluaudite-type structure, and their catalytic activity in butan-2-ol conversion

International Nuclear Information System (INIS)

Kacimi, Mohammed; Ziyad, Mahfoud; Hatert, Frederic

2005-01-01

AgCaCdMg 2 (PO 4 ) 3 and AgCd 2 Mg 2 (PO 4 ) 3 , two new compounds with the alluaudite-type structure, were synthesized by a solid state reaction in air at 750 deg. C. The X-ray powder diffraction pattern of AgCaCdMg 2 (PO 4 ) 3 indicates the presence of small amounts of (Ca, Mg) 3 (PO 4 ) 2 with the whitlockite structure, as impurity, whereas AgCd 2 Mg 2 (PO 4 ) 3 is constituted by pure alluaudite. The Rietveld refinements of the X-ray powder diffraction patterns indicate an ordered cationic distribution for AgCd 2 Mg 2 (PO 4 ) 3 , with Ag on A(2)', Cd on A(1) and M(1), and Mg on M(2), whereas a disordered distribution of Cd and Ca between the A(1) and M(1) sites is observed for AgCaCdMg 2 (PO 4 ) 3 . The catalytic properties of these compounds has been measured in reaction of butan-2-ol dehydrogenation. In the absence of oxygen, both samples exhibit poor dehydrogenation activity. All samples displayed no dehydration activity. Introduction of oxygen into the feed changed totally the catalytic behavior of the catalysts. The production of methyl ethyl ketone increases with time on stream and the reaction temperature. AgCaCdMg 2 (PO 4 ) 3 is more efficient than AgCd 2 Mg 2 (PO 4 ) 3

Influence of Cobalt Doping on the Physical Properties of Zn0.9Cd0.1S Nanoparticles

Directory of Open Access Journals (Sweden)

Gupta Hari Om

2009-01-01

Full Text Available Abstract Zn0.9Cd0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn0.9Cd0.1S sphalerite phase. For low cobalt concentration (≤0.05 M particle size, d XRDis ~3.5 nm, while for high cobalt concentration (>0.05 M particle size decreases abruptly (~2 nm as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.

Growth and characterization of indium-doped Cd1−xZnxTe crystal by traveling heater method

International Nuclear Information System (INIS)

Wei, Gaoli; Wang, Linjun; Zhang, Jijun; Yuan, Zhenwen; Qin, Kaifeng; Min, Jiahua; Liang, Xiaoyan; Xia, Yiben

2013-01-01

An indium-doped detector grade Cd 0.9 Zn 0.1 Te crystal was grown by the THM technique from Te-rich solution. The as-grown crystal showed the dark resistivity of (1–3)×10 10 Ω cm. Through IR transmission microscopy Te inclusion with regular triangular or circular shapes could be observed, and the size of Te inclusion was around 7 μm and the concentration was ∼10 5 cm −3 . The impurity concentrations were greatly reduced for the THM grown CZT, as compared to the Bridgman method grown CZT. A resolution of 8.5% was achieved under the 662 keV 137 Cs gamma ray radiation at room temperature for the as-grown CZT samples. -- Highlights: ► Detector grade Cd 1−x Zn x Te has been successfully grown by the THM technique. ► The as-grown CZT has a resistivity of ∼10 10 Ω cm. ► Te inclusions' size and concentration were comparable to the commercial CZT. ► A resolution of 8.5% was achieved for the 137 Cs 662 keVgamma line

sp-d Exchange Interactions in Wave Function Engineered Colloidal CdSe/Mn:CdS Hetero-Nanoplatelets.

Science.gov (United States)

Muckel, Franziska; Delikanli, Savas; Hernández-Martínez, Pedro Ludwig; Priesner, Tamara; Lorenz, Severin; Ackermann, Julia; Sharma, Manoj; Demir, Hilmi Volkan; Bacher, Gerd

2018-03-14

In two-dimensional (2D) colloidal semiconductor nanoplatelets, which are atomically flat nanocrystals, the precise control of thickness and composition on the atomic scale allows for the synthesis of heterostructures with well-defined electron and hole wave function distributions. Introducing transition metal dopants with a monolayer precision enables tailored magnetic exchange interactions between dopants and band states. Here, we use the absorption based technique of magnetic circular dichroism (MCD) to directly prove the exchange coupling of magnetic dopants with the band charge carriers in hetero-nanoplatelets with CdSe core and manganese-doped CdS shell (CdSe/Mn:CdS). We show that the strength of both the electron as well as the hole exchange interactions with the dopants can be tuned by varying the nanoplatelets architecture with monolayer accuracy. As MCD is highly sensitive for excitonic resonances, excited level spectroscopy allows us to resolve and identify, in combination with wave function calculations, several excited state transitions including spin-orbit split-off excitonic contributions. Thus, our study not only demonstrates the possibility to expand the extraordinary physical properties of colloidal nanoplatelets toward magneto-optical functionality by transition metal doping but also provides an insight into the excited state electronic structure in this novel two-dimensional material.

Investigations of Al:CdS/PVA nanocomposites: A joint theoretical and experimental approach

Energy Technology Data Exchange (ETDEWEB)

Bala, Vaneeta, E-mail: b.vnita@gmail.com; Sharma, Mamta, E-mail: mamta.phy85@gmail.com; Tripathi, S.K., E-mail: surya@pu.ac.in; Kumar, Ranjan, E-mail: ranjan@pu.ac.in

2014-08-01

In the present work we investigate the aluminium doped cadmium sulphide (Al:CdS) nanoparticles embedded in polyvinyl alcohol (PVA) matrix by chemical route and density functional theory (DFT) based simulations. Supertetrahedron (T{sub n}) cluster models are considered for the simulation of CdS nanoparticles. Using DFT simulations on T{sub n} clusters, we observe that band gap of ligated clusters is slightly more as compare to bare clusters. This indicates the ability of organic ligands (PVA) to open the band gap of inorganic CdS nanoclusters. Negative value of binding energy indicates the stability of the inorganic–organic hybrid system. Frontier molecular orbitals (FMOs) indicate the charge transfer between organic and inorganic moieties which provides stability and longevity to nanoparticles, a prime function of ligands in nanocomposites. Absorption spectra of pure and doped clusters are calculated using time dependent density functional theory (TDDFT). CdS/PVA and Al:CdS/PVA samples are synthesized at room temperature by chemical method. Their structure, size and band gap is characterized by XRD, TEM, FTIR and UV spectroscopy. Optical band gap values as observed experimentally are in agreement with simulated TDDFT results. - Highlights: • Highly c-axis oriented Al doped CdS/PVA nanocomposites were deposited on glass slide using aqueous solutions. • Optical band gap reduced on Al doping. • DFT is used to simulate atomistic models of inorganic–organic hybrid nanocomposites. • FMOs used to study charge transfer behaviour between inorganic and organic moieties.

Doped Heterojunction Used in Quantum Dot Sensitized Solar Cell

Directory of Open Access Journals (Sweden)

Yanyan Gao

2014-01-01

Full Text Available Incorporated foreign atoms into the quantum dots (QDs used in heterojunction have always been a challenge for solar energy conversion. A foreign atom indium atom was incorporated into PbS/CdS QDs to prepare In-PbS/In-CdS heterojunction by successive ionic layer adsorption and reaction method which is a chemical method. Experimental results indicate that PbS or CdS has been doped with In by SILAR method; the concentration of PbS and CdS which was doped In atoms has no significantly increase or decrease. In addition, incorporating of Indium atoms has resulted in the lattice distortions or changes of PbS or CdS and improved the light harvest of heterojunction. Using this heterojunction, Pt counter electrode and polysulfide electrolyte, to fabricate quantum dot sensitized solar cells, the short circuit current density ballooned to 27.01 mA/cm2 from 13.61 mA/cm2 and the open circuit voltage was improved to 0.43 V from 0.37 V at the same time.

Surface preparation effects on efficient indium-tin-oxide-CdTe and CdS-CdTe heterojunction solar cells

Science.gov (United States)

Werthen, J. G.; Fahrenbruch, A. L.; Bube, R. H.; Zesch, J. C.

1983-05-01

The effects of CdTe surface preparation and subsequent junction formation have been investigated through characterization of ITO/CdTe and CdS/CdTe heterojunction solar cells formed by electron beam evaporation of indium-tin-oxide (ITO) and CdS onto single crystal p-type CdTe. Surfaces investigated include air-cleaved (110) surfaces, bromine-in-methanol etched (110) and (111) surfaces, and teh latter surfaces subjected to a hydrogen heat treatment. Both air-cleaved and hydrogen heat treated surfaces have a stoichiometric Cd to Te ratio. The ITO/CdTe junction formation process involves an air heat treatment, which ahs serious effects on the behavior of junctions formed on these surfaces. Etched surfaces which have a large excesss of Te, are less affected by the junction formation process and result in ITO/CdTe heterojunctions with solar efficiencies of 9% (Vsc =20 mA/cm2). Use of low-doped CdTe results in junctions characterized by considerably larger open-circuit votages (Voc =0.81 V) which are attributable to increasing diode factors caused by a shift from interfacial recombination to recombination in the depletion region. Resulting solar efficiencies reach 10.5% which is the highest value reported to date for a genuine CdTe heterojunction, CdS/CdTe heterojunctions show a strong dependence on CdTe surface condition, but less influence on the junction formation process. Solar efficiencies of 7.5% on an etched and heat treated surface are observed. All of these ITO/CdTe and CdS/CdTe heterojunctions have been stable for at least 10 months.

First principles study of structural, elastic, electronic and magnetic properties of Mn-doped AlY (Y=N, P, As) compounds

Energy Technology Data Exchange (ETDEWEB)

Sajjad, M. [School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Alay-e-Abbas, S.M. [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Department of Physics, Government College University, Faisalabad, Allama Iqbal Road, Faisalabad 38000 (Pakistan); Zhang, H.X. [School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Beijing Key Laboratory of Work Safety Intelligent Monitoring (Beijing University of Posts and Telecommunications), Beijing 100876 (China); Noor, N.A. [Centre for High Energy Physics, University of the Punjab, Quaid-e-Azam Campus, 54590 Lahore (Pakistan); Saeed, Y. [Department of Physics, Government College University, Faisalabad, Allama Iqbal Road, Faisalabad 38000 (Pakistan); Shakir, Imran [Deanship of scientific research, College of Engineering, King Saud University, P. O. BOX 800, Riyadh 11421 (Saudi Arabia); Shaukat, A., E-mail: schaukat@gmail.com [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan)

2015-09-15

We investigate zinc-blende phase Al{sub 0.75}Mn{sub 0.25}Y (Y=N, P, As) compounds using full-potential linear-augmented-plane wave plus local-orbital method. For computing structural and elastic properties the Generalized Gradient Approximation (GGA) has been used; whereas the electronic and magnetic properties are examined at the optimized GGA lattice parameters by employing modified Becke and Johnson local density approximation. All these compounds are found to be stable in ferromagnetic ordering in the zinc-blende structure which is supported by the computed elastic constants. The nature of electronic band structure are calculated and the nature of band gaps in the doped system is analyzed. The results are examined to identify exchange mechanism which is the main source of introducing ferromagnetism in the compounds under investigation. Spin charge density contour plots in the (1 1 0) plane and the evaluation of s–p and p–d exchange constants (N{sub 0}α and N{sub 0}β) are evaluated for understanding bonding and exchange splitting process, respectively. - Highlights: • Spin-polarized DFT investigation Mn-doped AlN, AlP and AlAs is reported. • Structrual and elastic properites are computed for evaluating stability. • mBJLDA used for appropriate treatment of d states of Mn for electronic properties. • Half metallicity, ferromagnetic stability and exchange constants are evaluated.

Simulation of MeV electron energy deposition in CdS quantum dots absorbed in silicate glass for radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Baharin, R; Hobson, P R; Smith, D R, E-mail: ruzalina.baharin@brunel.ac.u [Centre for Sensors and Instrumentation, School of Engineering and Design, Brunel University, Uxbridge UB8 3PH (United Kingdom)

2010-09-01

We are currently developing 2D dosimeters with optical readout based on CdS or CdS/CdSe core-shell quantum-dots using commercially available materials. In order to understand the limitations on the measurement of a 2D radiation profile the 3D deposited energy profile of MeV energy electrons in CdS quantum-dot-doped silica glass have been studied by Monte Carlo simulation using the CASINO and PENELOPE codes. Profiles for silica glass and CdS quantum-dot-doped silica glass were then compared.

Simulation of MeV electron energy deposition in CdS quantum dots absorbed in silicate glass for radiation dosimetry

International Nuclear Information System (INIS)

Baharin, R; Hobson, P R; Smith, D R

2010-01-01

We are currently developing 2D dosimeters with optical readout based on CdS or CdS/CdSe core-shell quantum-dots using commercially available materials. In order to understand the limitations on the measurement of a 2D radiation profile the 3D deposited energy profile of MeV energy electrons in CdS quantum-dot-doped silica glass have been studied by Monte Carlo simulation using the CASINO and PENELOPE codes. Profiles for silica glass and CdS quantum-dot-doped silica glass were then compared.

Computational analysis of the amplified spontaneous emission in quantum dot doped plastic optical fibers

International Nuclear Information System (INIS)

Peng, Xuefeng; Han, Yinxia; Hu, Guoqiang; Wu, Pinghui

2014-01-01

The properties of amplified spontaneous emission (ASE) in CdSe/ZnS quantum dot (QD) doped step-index polymer optical fibers (POFs) were computationally analyzed in this paper. A theoretical model based on the rate equations between two main energy levels of CdSe/ZnS QD was built in terms of time (t), distance traveled by light (z) and wavelength (λ), which can describe the ASE successfully. Through analyzing the spectral evolution with distance of the pulses propagating along the CdSe/ZnS QD doped POFs, dependences of the ASE threshold and the slope efficiency on the numerical aperture were obtained. Compared to the ASE in common dye-doped POFs, the pump threshold was just about 1/1000, but the slope efficiency was much higher. (paper)

Hyperfine interaction measurements in biological compounds: the case of hydroxyapatite

International Nuclear Information System (INIS)

Leite Neto, Osmar Flavio da Silveira

2014-01-01

The use o nanoparticles in current medicine are under intense investigation. The possible advantages proposed by these systems are very impressive and the results may be quite schemer. In this scenario, the association of nanoparticles with radioactive materials (radionuclide) may be the most important step since the discovery of radioactive for nuclear medicine and radiopharmacy, especially for cancer targeting and therapy. The hyperfine interaction of the nuclear probe 111 Cd in the Hydroxyapatite compounds has been investigated by perturbed angular correlation (PAC) spectroscopy in room temperature for the hydroxyapatite made in the temperatures of 90°C, 35°C and with Ho doped, both thermalized and not. The thermalized samples were heated to T= 1273 K for 6 h. The 111 Cd was broadcast in the structure of the material by diffusion, closing in quartz tubes were heated – together with the radioactive PAC probe 111 In/ 111 Cd to T = 1073 K for 12 h. In not thermalized samples the PAC spectra indicate a distribution of frequency, but in the thermalized samples, the PAC spectra shows the presence of β-tri calcium phosphate in the structure of this kind of Hydroxyapatite. (author)

Neutron investigation of Ru-doped Nd1/2Ca1/2MnO3. Comparison with Cr-doped Nd1/2Ca1/2MnO3

International Nuclear Information System (INIS)

Moritomo, Yutaka; Nonobe, Toshihiko; Machida, Akihiko; Ohoyama, Kenji

2002-01-01

Lattice and magnetic properties are investigated for 3% Ru- and Cr-doped Nd 1/2 Ca 1/2 MnO 3 . The parent Nd 1/2 Ca 1/2 MnO 3 is a charge-ordered insulator (T CO =250K). With decreasing temperature below ≅210K, these compounds are separated into two perovskite phases, that is, the long-c and short-c phases. The long-c region shows a ferromagnetic transition at T C ≅210K for the Ru-doped compound and ≅130K for the Cr-doped compound, while the short-c region shows antiferromagnetic transition at T N ≅150K for Ru and ≅110K for Cr. We discuss the origin of the enhanced T C for the Ru-doped compound in terms of the effective one-electron bandwidth W of the e g -band. (author)

Luminescence properties of CdSiO3:Mn2+ phosphor

International Nuclear Information System (INIS)

Lei Bingfu; Liu Yingliang; Ye Zeren; Shi Chunshan

2004-01-01

A novel long-lasting phosphor CdSiO 3 :Mn 2+ is reported in this paper. The Mn 2+ -doped CdSiO 3 phosphor emits orange light with CIE chromaticity coordinates x=0.5814 and y=0.4139 under 254 nm UV light excitation. In the emission spectrum of 1% Mn 2+ -doped CdSiO 3 phosphor, there is a broad emission band centered at 575 nm which can be attributed to the spin-forbidden transition of the d-orbital electron associated with the Mn 2+ ion. The phosphorescence can be seen by the naked eyes in the dark clearly even after the 254 nm UV irradiation have been removed for about 1 h. The mechanism of the origin of the long-lasting phosphorescence was discussed using the thermoluminescence curves

Electrical properties of cadmium telluride films doped with antimony

International Nuclear Information System (INIS)

Atdaev, B.S.; Garyagdyev, G.; Grin', V.F.; Noskov, A.I.

1989-01-01

Effect of cadmium telluride doping with antimony on electric and photoelectric properties is investigated. Temperature dependence of dark (σ d ) and photoconductivity (σ p ) during excitation from the range of proper absorption in the temperature range 77-300 K and spectral distribution of photoconductivity at 300 K are investigated. It is shown that in the process of doping antimony diffusses intensively over CdTe grain boundaries, decreasing potential barriers between them and due to diffusion into CdTe grains it changes their electrical properties. The acceptor character of antimony impurity can be caused by antimony diffusion into tellurium sublattice owing to proximity of their ionic and covalent radii

Solution-Processed n-Type Graphene Doping for Cathode in Inverted Polymer Light-Emitting Diodes.

Science.gov (United States)

Kwon, Sung-Joo; Han, Tae-Hee; Kim, Young-Hoon; Ahmed, Towfiq; Seo, Hong-Kyu; Kim, Hobeom; Kim, Dong Jin; Xu, Wentao; Hong, Byung Hee; Zhu, Jian-Xin; Lee, Tae-Woo

2018-02-07

n-Type doping with (4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl) dimethylamine (N-DMBI) reduces a work function (WF) of graphene by ∼0.45 eV without significant reduction of optical transmittance. Solution process of N-DMBI on graphene provides effective n-type doping effect and air-stability at the same time. Although neutral N-DMBI act as an electron receptor leaving the graphene p-doped, radical N-DMBI acts as an electron donator leaving the graphene n-doped, which is demonstrated by density functional theory. We also verify the suitability of N-DMBI-doped n-type graphene for use as a cathode in inverted polymer light-emitting diodes (PLEDs) by using various analytical methods. Inverted PLEDs using a graphene cathode doped with N-DMBI radical showed dramatically improved device efficiency (∼13.8 cd/A) than did inverted PLEDs with pristine graphene (∼2.74 cd/A). N-DMBI-doped graphene can provide a practical way to produce graphene cathodes with low WF in various organic optoelectronics.

HgCdTe photovoltaic detectors on Si substrates

International Nuclear Information System (INIS)

Zanio, K.R.; Bean, R.C.

1988-01-01

HgCdTe photovoltaic detectors have been fabricated on Si substrates through intermediate CdTe/GaAs layers. Encapsulation of the GaAs between the CdTe and Si prevents unintentional doping of the HgCdTe by Ga and As. Uniform epitaxial GaAs is grown on three inch diameter Si substrates. Detectors on such large area Si substrates will offer hybrid focal plane arrays whose dimensions are not limited by the difference between the coefficients of thermal expansion of the Si signal processor and the substrate for the HgCdTe detector array. The growth of HgCdTe detectors on the Si signal processors for monolithic focal plane arrays is also considered. 40 references

Dynamic hyperfine interactions in {sup 111}In({sup 111}Cd)-doped ZnO semiconductor: PAC results supported by ab initio calculations

Energy Technology Data Exchange (ETDEWEB)

Munoz, Emiliano L., E-mail: munoz@fisica.unlp.edu.ar [Departamento de Fisica and Instituto de Fisica La Plata (IFLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 67, 1900 La Plata (Argentina); Mercurio, Marcio E.; Cordeiro, Moacir R.; Pereira, Luciano F.D.; Carbonari, Artur W. [Instituto de Pesquisas Energeticas y Nucleares-IPEN-CNEN/SP, Sao Paulo (Brazil); Renteria, Mario [Departamento de Fisica and Instituto de Fisica La Plata (IFLP, CONICET La Plata), Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CC 67, 1900 La Plata (Argentina)

2012-08-15

In this work, we present results of Time-Differential {gamma}-{gamma} Perturbed-Angular-Correlations (PAC) experiments performed in {sup 111}Cd-doped ZnO semiconductor. The PAC technique has been applied in order to characterize the electric-field-gradient (EFG) tensor at ({sup 111}In (EC){yields}) {sup 111}Cd nuclei located, as was later demonstrated, at defect-free cation sites of the ZnO host structure. The PAC experiments were performed in the temperature range of 77-1075 K. At first glance, the unexpected presence of low-intensity dynamic hyperfine interactions was observed, which were analyzed with a perturbation factor based on the Baeverstam and Othaz model. The experimental EFG results were compared with ab initio calculations performed with the Full-Potential Augmented Plane Wave plus local orbital (FP-APW+lo) method, in the framework of the Density Functional Theory (DFT), using the Wien2K code. The presence of the dynamic hyperfine interactions has been analyzed enlightened by the FP-APW+lo calculations of the EFG performed as a function of the charge state of the cell. We could correlate the large strength of the dynamic hyperfine interaction with the strong variation of the EFG due to changes in the electronic charge distribution in the Cd vicinity during the time-window of the PAC measurement. It was also revealed that the Cd impurity decays to a final stable neutral charge state (Cd{sup 2+}) fast enough (in few ns) to produce the nearly undamped observed PAC spectra.

Enhancement of CdSiO3: Tb3+ green long-lasting phosphors by co-doping with Re3+ (Re3+=Gd3+, Y3+, La3+) ions

International Nuclear Information System (INIS)

Zeng, Wei; Wang, Yuhua; Han, Shaochun; Chen, Wenbo; Li, Gen

2014-01-01

CdSiO 3 : Tb 3+ , Re 3+ long-lasting phosphors were synthesized by the conventional high temperature solid-state method. A green-light phosphorescence phenomenon, which was associated with the 5 D 4 → 7 F J (J=6, 5, 4, 3) transitions of the Tb 3+ ion, was observed. Introduction of Re 3+ (Re 3+ =Gd 3+ , Y 3+ , La 3+ ) ions, which deepens the depth (E t ) or/and increases the density (n 0 ) of traps, greatly improved the afterglow properties of CdSiO 3 : Tb 3+ . Possible mechanism of CdSiO 3 : Tb 3+ , Re 3+ was discussed in this work. - Highlights: • CdSiO 3 : Tb 3+ , Re 3+ samples enrich the color of long-lasting afterglow phosphors in CdSiO 3 host. • Both the afterglow intensity and the lasting time are greatly enhanced for the co-doped samples, especially for Cd 0.96 SiO 3 : Tb 0.03 3+ , La 0.01 3+ . • Introduction of Re 3+ (Re 3+ =Gd 3+ , Y 3+ , La 3+ ) ions, which deepens the depth (E t ) or increase density(n 0 ) of traps, greatly improved the afterglow properties of CdSiO 3 : Tb 3+

Semiconductor CdF2:Ga and CdF2:In Crystals as Media for Real-Time Holography

Science.gov (United States)

Ryskin, Alexander I.; Shcheulin, Alexander S.; Angervaks, Alexander E.

2012-01-01

Monocrystalline cadmium fluoride is a dielectric solid that can be converted into a semiconductor by doping with donor impurities and subsequent heating in the reduction atmosphere. For two donor elements, Ga and In, the donor (“shallow”) state is a metastable one separated from the ground (“deep”) state by a barrier. Photoinduced deep-to-shallow state transition underlies the photochromism of CdF2:Ga and CdF2:In. Real-time phase holograms are recorded in these crystals capable of following up optical processes in a wide frequency range. The features of photochromic transformations in CdF2:Ga and CdF2:In crystals as well as holographic characteristics of these media are discussed. Exemplary applications of CdF2-based holographic elements are given. PMID:28817009

Second order magnetic phase transition and scaling analysis in iron doped manganite La0.7Ca0.3Mn1−xFexO3 compounds

International Nuclear Information System (INIS)

Ginting, Dianta; Nanto, Dwi; Denny, Yus Rama; Tarigan, Kontan; Hadi, Syamsul; Ihsan, Mohammad; Rhyee, Jong-Soo

2015-01-01

We investigated magnetic properties of La 0.7 Ca 0.3 Mn 1−x Fe x O 3 (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La 0.7 Ca 0.3 Mn 1−x Fe x O 3 (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x<0.09) in previous reports. When we investigate the critical behavior of the compounds near T=T c by the modified Arrott plot, Kouvel–Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε −β M(H,ε) and renormalized field h=|ε| β+γ H. Temperature-dependent effective exponents β eff and γ eff correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration. - Highlights: • The ferromagnetic phase transition is of second order in La 0.7 Ca 0.3 Mn 1−x Fe x O 3 . • The critical exponents are in between the 3D Heisenberg and mean-field models. • The ferromagnetic interaction becomes more itinerant by Fe-doping

Synthesis and study of the magnetic properties of thallium-based over-doped superconducting compounds; Synthese et etude des proprietes magnetiques des composes supraconducteurs surdopes a base de thallium

Energy Technology Data Exchange (ETDEWEB)

Opagiste, C.

1994-07-01

The synthesis, structure and magnetic properties of the normal and superconducting states of over-doped Tl{sub 2} Ba{sub 2} Cu O{sub 6{+-}x} and Tl{sub 2} Ba{sub 2} Ca Cu{sub 2} O{sub 8{+-}x} superconducting compounds, are presented. Synthesis under high pressure using Tl{sub 2} Ba{sub 2} O{sub 5} as a precursor avoids thallium losses and Ba Cu O{sub 2} formation. The entire over-doped region has been investigated (Tc ranging from 0 to 92 K) and the different stability zones for the two crystallographic structures have been explored. The orthorhombic structure is shown to be stoichiometric in cations, while the tetragonal one could present thallium deficiency. Clear correlations have been established between Tc and the lattice parameters for the two phases. It has been observed that the Meissner fraction increased with Tc and that the reversibility domain was more extended for samples having a Tc near the maximal value, which must be linked to the decrease of the anisotropy with over-doping. In the reversible regime, the mixed state is affected by thermal fluctuations around Tc. Evolution of the penetration depth with Tc is examined; it shows that the optimum doped compound (maximal Tc) behaves as a BCS type superconductor. The over-doping results in a penetration depth behaviour which strongly deviates from the standard model (BCS, two fluids). The zero temperature, obtained by extrapolation, seems to be independent of the over-doping. 54 figs., 3 tabs., 168 refs.

C-V Calculations in CdS/CdTe Thin Films Solar Cells with a CdSxTe1-x Interlayer

Directory of Open Access Journals (Sweden)

A. Gonzalez-Cisneros

2013-01-01

Full Text Available In CdS/CdTe solar cells, chemical interdiffusion at the interface gives rise to the formation of an interlayer of the ternary compound CdSxCdTe1-x. In this work, we evaluate the effects of this interlayer in CdS/CdTe photovoltaic cells in order to improve theoretical results describing experimental C-V (capacitance versus voltage characteristics. We extended our previous theoretical methodology developed on the basis of three cardinal equations (Castillo-Alvarado et al., 2010. The present results provide a better fit to experimental data obtained from CdS/CdTe solar cells grown in our laboratory by the chemical bath deposition (for CdS film and the close-spaced vapor transport (for CdTe film techniques.

Hyperfine interactions in 111Cd-doped lutetium sesquioxide

International Nuclear Information System (INIS)

Errico, L.A.; Renteria, M.; Bibiloni, A.G.; Requejo, F.G.

1999-01-01

We report here first Perturbed Angular Correlation (PAC) results of the electric field gradient (EFG) characterisation at 111 Cd impurities located at both non-equivalent cation sites of the bixbyite structure of Lutetium sesquioxide, between room temperature (RT) and 1273 K. The comparison with results coming from a systematic 111 Cd PAC study in bixbyites and with point-charge model (PCM) predictions shows the presence of a trapped defect at RT in the neighbourhood of the asymmetric cation site, which is completely removed at T > 623 K. The anomalous EFG temperature dependence in Lu 2 O 3 can be described in the frame of a 'two-state' model with fluctuating interactions, which enables the experimental determination of the acceptor energy level introduced by the Cd impurity in the band-gap of the semiconductor and the estimation of the oxygen vacancy density in the sample

The synthesis and properties of some organometallic compounds containing group IV (Ge, Sn)-group II (Zn, Cd) metal---metal bonds

NARCIS (Netherlands)

Des Tombe, F.J.A.; Kerk, G.J.M. van der; Creemers, H.M.J.C.; Carey, N.A.D.; Noltes, J.G.

1972-01-01

The reactions of triphenylgermane and triphenyltin hydride with coordinatively saturated organozinc or organocadmium compounds give organometallic complexes containing Group IV (Ge, Sn)-Group II(Zn, Cd) metal---metal bonds. The 2,2′-bipyridine complexes show solvent-dependent charge-transfer

Identification of Ag-acceptors in $^{111}Ag^{111}Cd$ doped ZnTe and CdTe

CERN Document Server

Hamann, J; Deicher, M; Filz, T; Lany, S; Ostheimer, V; Strasser, F; Wolf, H; Wichert, T

2000-01-01

Nominally undoped ZnTe and CdTe crystals were implanted with radioactive /sup 111/Ag, which decays to /sup 111/Cd, and investigated by photoluminescence spectroscopy (PL). In ZnTe, the PL lines caused by an acceptor level at 121 meV are observed: the principal bound exciton (PBE) line, the donor-acceptor pair (DAP) band, and the two-hole transition lines. In CdTe, the PBE line and the DAP band that correspond to an acceptor level at 108 meV appear. Since the intensities of all these PL lines decrease in good agreement with the half-life of /sup 111/Ag of 178.8 h, both acceptor levels are concluded to be associated with defects containing a single Ag atom. Therefore, the earlier assignments to substitutional Ag on Zn- and Cd-lattice sites in the respective II-VI semiconductors are confirmed. The assignments in the literature of the S/sub 1/, S /sub 2/, and S/sub 3/ lines in ZnTe and the X/sub 1//sup Ag/, X/sub 2 //sup Ag//C/sub 1//sup Ag/, and C/sub 2//sup Ag/ lines in CdTe to Ag- related defect complexes are ...

S and Te inter-diffusion in CdTe/CdS hetero junction

Energy Technology Data Exchange (ETDEWEB)

Enriquez, J. Pantoja [Cuerpo Academico-Energia y Sustentabilidad, Universidad Politecnica de Chiapas, Eduardo J. Selvas S/N, Col. Magisterial, Tuxtla Gutierrez 29010, Chiapas (Mexico); Gomez Barojas, E. [CIDS-ICUAP, Apdo. Postal 1651, 72000 Puebla (Mexico); Silva Gonzalez, R.; Pal, U. [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Puebla (Mexico)

2007-09-22

Effects of post formation thermal annealing of the CdTe-CdS device on the inter-diffusion of S and Te at the junction in a substrate configuration device have been studied by Auger electron spectroscopy. While the migration of S and Te atoms increases with annealing temperature, the extent of S diffusion is always higher than the diffusion of Te atoms. Inter-diffusion of S and Te causes the formation of CdTe{sub 1-x}S{sub x} ternary compound at the CdTe-CdS interface. (author)

High luminescent fibers with hybrid SiO2-coated CdTe nanocrystals fabricated by electrospinning technique

International Nuclear Information System (INIS)

Cao, Yongqiang; Liu, Ning; Yang, Ping; Shi, Ruixia; Ma, Qian; Zhang, Aiyu; Zhu, Yuanna; Wang, Junpeng; Wang, Jianrong

2015-01-01

The polyvinylpyrrolidone (PVP) hybrid luminescent micro-/nanofibers doped with the novel hybrid SiO 2 -coated CdTe nanocrystals (HS-CdTe NCs) have been fabricated for the first time via the electrospinning technique. The morphologies and photoluminescence (PL) emissions of HS-CdTe/PVP micro-/nanofibers prepared by doping the HS-CdTe NCs with the different PL peak wavelength (571, 616, and 643 nm) in PVP fibers were investigated by optical and PL microscope. The results revealed that all the HS-CdTe/PVP hybrid fibers showed an ultralong length for several hundreds of micrometers and a relatively uniform diameter of 1000 ∼ 1200 nm. The hybrid fibers displayed a wavelength-tunable PL emission, determining by the PL of doped HS-CdTe NCs. Moreover, similar to the original PL properties of HS-CdTe NCs before the electrospinning, the HS-CdTe/PVP fibers also showed a series of superior PL properties, such as narrow and symmetry PL spectrum, high, and uniform brightness. For comparison purpose, we also prepared three CdTe/PVP hybrid fibers by doping the 553 nm, 600 nm, and 633 nm PL-emitting CdTe NCs respectively in PVP electrospinning fibers. The characterization results showed that, the obtained three CdTe/PVP hybrid fibers had a basically satisfactory micro-/nanofiber morphology with a long length and relatively uniform diameter, but all the fibers exhibited very weak PL emissions. The enormous contrast in PL properties between HS-CdTe/PVP and CdTe/PVP fibers should mainly be ascribed to the different connection modes of ligands with the NCs and the passivation effect of inert hybrid silica shell on HS-CdTe. It is hopeful that the high luminescent HS-CdTe/PVP micro-/nanofibers with the tunable PL peak wavelength would be a good candidate in the optical sensor, light-emitting devices (LEDs), nanometer-scale waveguides, and the other related photonic materials. - Highlights: • The HS-CdTe/PVP electrospun hybrid fibers were fabricated for the first time. • The

Sol–gel synthesis of long-lasting phosphors CdSiO3: Mn2+, RE3+ (RE = Tb, Eu, Nd) and luminescence mechanism research

International Nuclear Information System (INIS)

Qu, Xiaofei; Cao, Lixin; Liu, Wei; Su, Ge; Wang, Pingping; Schultz, Isabel

2012-01-01

Highlights: ► New long-lasting CdSiO 3 : Mn 2+ , RE 3+ (RE = Tb, Eu, Nd) phosphors were synthesized by a sol–gel method. ► The afterglow performance of the CdSiO 3 : Mn 2+ , Eu 3+ phosphor was the best. ► The role of RE 3+ co-doped into the CdSiO 3 : Mn 2+ matrix was discussed in this paper. -- Abstract: Mn 2+ and RE 3+ (RE = Tb, Eu, Nd) co-doped CdSiO 3 orange phosphors were prepared at 1050 °C by a sol–gel method. The phase and crystallinity of the synthesized materials were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The luminescence characteristics were analyzed using photoluminescence (PL) spectra, afterglow decay curves, long-lasting phosphorescence spectra, and thermoluminescence (TL) spectra. Due to the difference in co-doped rare earth ionic radii, it varied greatly in trap density and trap depth caused by the different defects deriving from RE 3+ ions co-doping into the CdSiO 3 : Mn 2+ host. The afterglow intensity and time for these samples increased as follows: CdSiO 3 : Mn 2+ 0.2%, Nd 3+ 0.8% 3 : Mn 2+ 0.4%, Tb 3+ 0.8% 3 : Mn 2+ 0.4%, Eu 3+ 0.3%. CdSiO 3 : Mn 2+ 0.4%, Eu 3+ 0.3% had the best afterglow properties, which could be due to the proper traps formed by Eu 3+ ions co-doping into the host. The role of RE 3+ co-doped into the CdSiO 3 : Mn 2+ matrix and the possible long-lasting phosphorescence process was also discussed in this paper.

Incorporation of Mn2+ into CdSe quantum dots by chemical bath co-deposition method for photovoltaic enhancement of quantum dot-sensitized solar cells.

Science.gov (United States)

Zhang, Chenguang; Liu, Shaowen; Liu, Xingwei; Deng, Fei; Xiong, Yan; Tsai, Fang-Chang

2018-03-01

A photoelectric conversion efficiency (PCE) of 4.9% was obtained under 100 mW cm -2 illumination by quantum-dot-sensitized solar cells (QDSSCs) using a CdS/Mn : CdSe sensitizer. CdS quantum dots (QDs) were deposited on a TiO 2 mesoporous oxide film by successive ionic layer absorption and reaction. Mn 2+ doping into CdSe QDs is an innovative and simple method-chemical bath co-deposition, that is, mixing the Mn ion source with CdSe precursor solution for Mn : CdSe QD deposition. Compared with the CdS/CdSe sensitizer without Mn 2+ incorporation, the PCE was increased from 3.4% to 4.9%. The effects of Mn 2+ doping on the chemical, physical and photovoltaic properties of the QDSSCs were investigated by energy dispersive spectrometry, absorption spectroscopy, photocurrent density-voltage characteristics and electrochemical impedance spectroscopy. Mn-doped CdSe QDs in QDSSCs can obtain superior light absorption, faster electron transport and slower charge recombination than CdSe QDs.

Specific features of band structure and optical anisotropy of Cu{sub 2}CdGeSe{sub 4} quaternary compounds

Energy Technology Data Exchange (ETDEWEB)

Brik, M.G., E-mail: brik@fi.tartu.ee [College of Mathematics and Physics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Institute of Physics, Jan Dlugosz University, Armii Krajowej 13/15, PL-42200 Czestochowa (Poland); Parasyuk, O.V. [Department of Chemistry, Eastern European National University, Voli 13, Lutsk 43025 (Ukraine); Myronchuk, G.L. [Department of Physics, Eastern European National University, Voli 13, Lutsk 43025 (Ukraine); Kityk, I.V. [Institute of Materials Science and Engineering, Technical University of Czestochowa, Al. Armii Krajowej 19, 42-200 Czestochowa (Poland)

2014-09-15

Complex theoretical and experimental studies of the band structure and optical functions of a new Cu{sub 2}CdGeSe{sub 4} quaternary crystal are reported. The benchmark band structure calculations were performed using the first-principles methods. As a result, the structural, electronic, optical and elastic properties of Cu{sub 2}CdGeSe{sub 4} were calculated in the general gradient approximation (GGA) and local density approximation (LDA). The calculated dielectric function and optical absorption spectra exhibit some anisotropic behavior. Detailed analysis of the band energy dispersion and effective space charge density helped in establishing the origin of the band structure anisotropy. All calculated properties are compared with the experimental data. An additional comparison with a similar crystal of Cu{sub 2}CdGeSe{sub 4} allowed to reveal the role played by the anions (S or Se) in formation of the optical properties of these two materials. - Highlights: • The structural, electronic, optical properties of Cu{sub 2}CdGeSe{sub 4} were calculated. • Pressure effects on these properties were modeled. • Comparison with a similar compound of Cu{sub 2}CdGeS{sub 4} was performed.

Preparation of cadmium-doped ZnO thin films by SILAR and their ...

Indian Academy of Sciences (India)

Cadmium-doped zinc oxide (Cd : ZnO) thin films were deposited from sodium zincate bath .... of complex ion on the substrate followed by reaction of the .... Intensity (a.u.). 0. 500 .... trum confirmed the presence of Zn, O and Cd elements in the.

Effect of low irradiation temperature on the thermoluminescent response of doped crystal NaCl:XCl2 :MnCl2(X=Ca, Cd)

International Nuclear Information System (INIS)

Ortiz M, A.; Cruz Z, E.; Furetta, C.; Kitis, G.

2009-10-01

Production of crystalline materials suitable thermoluminescent properties over a wide range of doses is becoming more important to evaluate different radiation fields. However, the thermoluminescence response and the structure of the glow curves may be modified by the participation of defects to low irradiation temperature. In this work it is analyzed the effect of the irradiation temperature, 77 and 200 K on the thermoluminescence response of crystal NaCl:XCl 2 :MnCl 2 (X=Ca, Cd) doubly doped. The glow curves obtained were analyzed using a deconvolution program of CGCD, and the response linearity was analyzed by supra linearity index. (Author)

Synthesis of CdTe QDs/single-walled aluminosilicate nanotubes hybrid compound and their antimicrobial activity on bacteria

Energy Technology Data Exchange (ETDEWEB)

Geraldo, Daniela A., E-mail: daniela.geraldo@unab.cl [Universidad Andres Bello, Departamento de Ciencias Quimicas (Chile); Arancibia-Miranda, Nicolas [CEDENNA, Center for the Development of Nanoscience and Nanotechnology (Chile); Villagra, Nicolas A. [Universidad Andres Bello, Laboratorio de Microbiologia, Facultad de Ciencias Biologicas (Chile); Mora, Guido C. [Universidad Andres Bello, Unidad de Microbiologia, Facultad de Medicina (Chile); Arratia-Perez, Ramiro [Universidad Andres Bello, Departamento de Ciencias Quimicas (Chile)

2012-12-15

The use of molecular conjugates of quantum dots (nanocrystalline fluorophores) for biological purposes have received much attention due to their improved biological activity. However, relatively, little is known about the synthesis and application of aluminosilicate nanotubes decorated with quantum dots (QDs) for imaging and treatment of pathogenic bacteria. This paper describes for a first time, the use of single-walled aluminosilicate nanotubes (SWNT) (imogolite) as a one-dimensional template for the in situ growth of mercaptopropionic acid-capped CdTe QDs. This new nanohybrid hydrogel was synthesized by a simple reaction pathway and their enhanced optical properties were monitored by fluorescence and UV-Vis spectroscopy, confirming that the use of these nanotubes favors the confinement effects of net CdTe QDs. In addition, studies of FT-IR spectroscopy and transmission electron microscopy confirmed the non-covalent functionalization of SWNT. Finally, the antimicrobial activity of SWNT coated with CdTe QDs toward three opportunistic multi-resistant pathogens such as Salmonella typhimurium, Acinetobacter baumannii, and Pseudomonas aeruginosa were tested. Growth inhibition tests were conducted by exposing growing bacteria to CdTe QDs/SWNT hybrid compound showing that the new nano-structured composite is a potential antimicrobial agent for heavy metal-resistant bacteria.

Synthesis of CdTe QDs/single-walled aluminosilicate nanotubes hybrid compound and their antimicrobial activity on bacteria

International Nuclear Information System (INIS)

Geraldo, Daniela A.; Arancibia-Miranda, Nicolás; Villagra, Nicolás A.; Mora, Guido C.; Arratia-Perez, Ramiro

2012-01-01

The use of molecular conjugates of quantum dots (nanocrystalline fluorophores) for biological purposes have received much attention due to their improved biological activity. However, relatively, little is known about the synthesis and application of aluminosilicate nanotubes decorated with quantum dots (QDs) for imaging and treatment of pathogenic bacteria. This paper describes for a first time, the use of single-walled aluminosilicate nanotubes (SWNT) (imogolite) as a one-dimensional template for the in situ growth of mercaptopropionic acid-capped CdTe QDs. This new nanohybrid hydrogel was synthesized by a simple reaction pathway and their enhanced optical properties were monitored by fluorescence and UV–Vis spectroscopy, confirming that the use of these nanotubes favors the confinement effects of net CdTe QDs. In addition, studies of FT-IR spectroscopy and transmission electron microscopy confirmed the non-covalent functionalization of SWNT. Finally, the antimicrobial activity of SWNT coated with CdTe QDs toward three opportunistic multi-resistant pathogens such as Salmonella typhimurium, Acinetobacter baumannii, and Pseudomonas aeruginosa were tested. Growth inhibition tests were conducted by exposing growing bacteria to CdTe QDs/SWNT hybrid compound showing that the new nano-structured composite is a potential antimicrobial agent for heavy metal-resistant bacteria.

Synthesis of CdTe QDs/single-walled aluminosilicate nanotubes hybrid compound and their antimicrobial activity on bacteria

Science.gov (United States)

Geraldo, Daniela A.; Arancibia-Miranda, Nicolás; Villagra, Nicolás A.; Mora, Guido C.; Arratia-Perez, Ramiro

2012-12-01

The use of molecular conjugates of quantum dots (nanocrystalline fluorophores) for biological purposes have received much attention due to their improved biological activity. However, relatively, little is known about the synthesis and application of aluminosilicate nanotubes decorated with quantum dots (QDs) for imaging and treatment of pathogenic bacteria. This paper describes for a first time, the use of single-walled aluminosilicate nanotubes (SWNT) (imogolite) as a one-dimensional template for the in situ growth of mercaptopropionic acid-capped CdTe QDs. This new nanohybrid hydrogel was synthesized by a simple reaction pathway and their enhanced optical properties were monitored by fluorescence and UV-Vis spectroscopy, confirming that the use of these nanotubes favors the confinement effects of net CdTe QDs. In addition, studies of FT-IR spectroscopy and transmission electron microscopy confirmed the non-covalent functionalization of SWNT. Finally, the antimicrobial activity of SWNT coated with CdTe QDs toward three opportunistic multi-resistant pathogens such as Salmonella typhimurium, Acinetobacter baumannii, and Pseudomonas aeruginosa were tested. Growth inhibition tests were conducted by exposing growing bacteria to CdTe QDs/SWNT hybrid compound showing that the new nano-structured composite is a potential antimicrobial agent for heavy metal-resistant bacteria.

The effect of alkaline doped catalysts on the CVD synthesis of carbon nanotubes

DEFF Research Database (Denmark)

Nemeth, Krisztian; Nemeth, Zoltan; Fejes, Dora

2011-01-01

The aim of this work was to develop new doped catalysts for chemical vapour deposition (CVD) synthesis in order to increase the quantity and quality of carbon nanotubes (CNTs). Doping compounds such as CsBr, CsCl, KBr and KCl were used to reach higher carbon deposit and carbon yield. The amount o...... of the dopant alkali compounds varied from 1 to 5%. As prepared CNTs were characterized by transmission electron microscopy (TEM), X‐ray diffraction (XRD) and Raman microscopy. Results revealed that both carbon yield and deposit could be increased over doped catalysts.......The aim of this work was to develop new doped catalysts for chemical vapour deposition (CVD) synthesis in order to increase the quantity and quality of carbon nanotubes (CNTs). Doping compounds such as CsBr, CsCl, KBr and KCl were used to reach higher carbon deposit and carbon yield. The amount...

Realizing near stoichiometric and highly transparent CdS:Mo thin films by a low-cost improved SILAR technique

Energy Technology Data Exchange (ETDEWEB)

Ravichandran, K. [P.G. and Research Department of Physics, AVVM Sri Pushpam College (Autonomous), Poondi, Thanjavur 613503, Tamil Nadu (India); Nisha Banu, N. [P.G. and Research Department of Physics, AVVM Sri Pushpam College (Autonomous), Poondi, Thanjavur 613503, Tamil Nadu (India); Research Department of Physics, Kunthavai Naachiyaar Government Arts College for Women (Autonomous), Thanjavur 613007, Tamil Nadu (India); Baneto, M. [CUER-UL, Universite de Lome, BP 1515, Lome (Togo); Senthamil Selvi, V. [Research Department of Physics, Kunthavai Naachiyaar Government Arts College for Women (Autonomous), Thanjavur 613007, Tamil Nadu (India)

2016-02-15

Undoped and molybdenum doped CdS thin films were deposited on glass substrates using Improved Successive Ionic Layer Adsorption and Reaction (ISILAR) technique. The Mo doping level was varied from 0 to 15 at.% in steps of 5 at.%. The XRD analysis shows that all the films are polycrystalline with cubic structure and grow preferentially along the (111) plane. The crystallite size increases gradually with the increase in Mo doping level up to 10 at.% and decreases with further doping. The morphological studies reveal that Mo doping significantly affects the grains size. Qualitative and quantitative compositional analysis show that near stoichiometric undoped and Mo doped CdS thin films can be achieved using this ISILAR technique. All the films exhibit high transparency in the visible region with an average transmittance in the range of 85-95%. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Electronic structure and optical properties in ZnO:M(Co, Cd)

International Nuclear Information System (INIS)

Palacios, P.; Aguilera, I.; Wahnon, P.

2010-01-01

ZnO doped with some transitions metals (ZnO:M) has several significant potential application. ZnO:Co is proposed to be used in advanced spintronic devices due to its high Curie temperature and large magnetic moments per transition metal. ZnO:Cd has potential applications in short-wavelength optoelectronic devices. This work focuses on an ab-initio study of the electronic and optical properties of ZnO:M doped with Co, and Cd. Theoretical calculations have been done with different computational codes, using the density functional theory (DFT) at the GGA and GGA+U level. The latter introduces a Hubbard term correction in the 'd' levels of the Zn and Co. We used different supercells in order to have different realistic dilution levels which can be achieved in experiments. Doping effects on the features of the optical absorption are also studied and analysed in this work.

Luminescence in Mn-doped CdS nanocrystals

Indian Academy of Sciences (India)

Wintec

and the Mn d levels occur at two different energies, allowed us to study the PL lifetime decay behaviour of both kinds of .... seen from the XRD analysis, the size of the nanocrystals .... levels couple to the CdS electronic states and the excited.

Synthesis, structures and electroluminescence properties of CdS:In/Si nanoheterostructure array

Energy Technology Data Exchange (ETDEWEB)

Yan, Ling Ling; Cai, Hong Xin; Chen, Liang [Henan Polytechnic University, School of Physics and Electronic Information Engineering, Jiaozuo (China)

2017-10-15

An In-doped CdS/Si nanoheterojunction (CdS:In/Si-NPA) is prepared by depositing an In-doped CdS thin film onto a Si nanoporous pillar array (Si-NPA) via a successive ionic layer adsorption and reaction method. Based on the measured J-V characteristic curve, the nanoheterojunction exhibits a good rectifying behavior with a low forward turn-on voltage (2.2 V), a small leakage current density (0.5 mA/cm{sup 2} at - 3 V) and a high reverse breakdown voltage (> 8 V). The electroluminescence (EL) measurements reveal that a broadband emerges between 400 and 700 nm, and this band is confirmed as a white light emission based on the value of the chromaticity coordinate. The EL properties, including the CIE chromaticity coordinates, Colour Rendering Index and correlated color temperature, can be tuned by the applied voltage. The generation mechanism of the EL can be well interpreted depending on the energy band structure of CdS:In/Si-NPA. The green band should be attributed to the band-edge emission of CdS and the yellow emission may be related to Cd interstitial. These results highlight the potential of CdS:In/Si-NPA as a light source for future white light emitting devices. (orig.)

Synthesis and structural, optical and thermal properties of CdS:Zn2+ nanoparticles

Science.gov (United States)

Muruganandam, S.; Anbalagan, G.; Murugadoss, G.

2014-12-01

Undoped and Zn (1-5, 10 %) -doped CdS nanoparticles were successfully synthesized by chemical method and polyvinylpyrrolidone was used as capping agent. The morphology and crystalline structure of the samples were studied by transmission electron microscopy and X-ray diffraction. The average particle size of the spherical nanoparticles determined by these techniques was of the order of 2.5-6 nm. The functional groups of the capping agent on CdS:Zn2+ surface were identified by FT-IR study. The band gap of the nanoparticles was calculated using UV-visible absorption spectra and the result showed that the band gap values were dramatically blue shifted from the bulk CdS. The optimum concentration of the doping ions was selected through absorption study. Photoluminescence of the CdS:Zn2+ nanoparticle showed strong blue and green emission. The thermal properties of the nanoparticles were analyzed by thermogravimetric-differential thermal analysis.

Poly thiophene hydrophobic and hydrophilic compounds, silver and iodine synthesized by plasma

International Nuclear Information System (INIS)

Palacios, J.C.; Chavez, J.A.; Olayo, M.G.; Cruz, G.J.

2007-01-01

Compounds in thin films of poly thiophene with silver and poly thiophene doped with iodine and silver using splendor discharges were synthesized. It is studied the wettability of the compounds and its transport properties. It was found that the compounds can modify their hydrophilic to hydrophobic behavior controlling their surface ruggedness and the metallic content. The doped with iodine plays a fundamental paper in the modification of the ruggedness of the compounds. (Author)

Enhancement of organic light-emitting device performances with Hf-doped indium tin oxide anodes

International Nuclear Information System (INIS)

Chen, T.-H.; Liou, Y.; Wu, T.J.; Chen, J.Y.

2004-01-01

We have enhanced the luminance and the power efficiency of organic light-emitting devices with Hf-doped indium tin oxide (ITO) anodes instead of a CuPc layer. The Hf-doped ITO layer with a thickness of 15 nm was deposited on top of the ITO anode. Less than 10 mol. % of Hf was doped in ITO films by adjusting the sputtering rates of both sources. The highest work function of the Hf-doped ITO layers was 5.4 eV at the Hf concentrations about 10 mol. %. The driving voltages of the device have been reduced by 1 V. A luminance of 1000 cd/m 2 at 7 mA/cm 2 , a current efficiency of 14 cd/A, and a power efficiency of 6 lm/W at 6 mA/cm 2 have been achieved in the device with a 4 mol. % Hf-doped ITO layer (work function=5.2 eV). In general, the performance was about 50% better than the device with a CuPc buffer layer

2-(2-Hydroxyphenyl)imidazole-based four-coordinate organoboron compounds with efficient deep blue photoluminescence and electroluminescence.

Science.gov (United States)

Zhang, Zhenyu; Zhang, Zuolun; Zhang, Hongyu; Wang, Yue

2017-12-19

Two new four-coordinate organoboron compounds with 2-(2-hydroxyphenyl)imidazole derivatives as the chelating ligands have been synthesized. They possess high thermal stability and are able to form an amorphous glass state. Crystallographic analyses indicate that the differences in ligand structure cause the change of ππ stacking character. The CH 2 Cl 2 solutions and thin films of these compounds display bright blue emission, and these compounds have appropriate HOMO and LUMO energy levels for carrier injection in OLEDs. By utilizing the good thermal and luminescent properties, as well as the proper frontier orbital energy levels, bright non-doped OLEDs with a simple structure have been realized. Notably, these simple devices show deep blue electroluminescence with the Commission Internationale de l'Éclairage (CIE) coordinate of ca. (0.16, 0.08), which is close to the CIE coordinate of (0.14, 0.08) for standard blue defined by the National Television System Committee. In addition, one of the devices exhibits good performance, showing brightness, current efficiency, power efficiency and external quantum efficiency up to 2692 cd m -2 , 2.50 cd A -1 , 1.81 lm W -1 and 3.63%, respectively. This study not only provides good deep-blue emitting OLED materials that are rarely achieved by using four-coordinate organoboron compounds, but also allows a deeper understanding of the structure-property relationship of 2-(2-hydroxyphenyl)imidazole-based boron complexes, which benefits the further structural design of this type of material.

Numerical modelling of CIGS/CdS solar cell

Science.gov (United States)

Devi, Nisha; Aziz, Anver; Datta, Shouvik

2018-05-01

In this work, we design and analyze the Cu(In,Ga)Se2 (CIGS) solar cell using simulation software "Solar Cell Capacitance Simulator in One Dimension (SCAPS-1D)". The conventional CIGS solar cell uses various layers, like intrinsic ZnO/Aluminium doped ZnO as transparent oxide, antireflection layer MgF2, and electron back reflection (EBR) layer at CIGS/Mo interface for good power conversion efficiency. We replace this conventional model by a simple model which is easy to fabricate and also reduces the cost of this cell because of use of lesser materials. The new designed model of CIGS solar cell is ITO/CIGS/OVC/CdS/Metal contact, where OVC is ordered vacancy compound. From this simple structure, even at very low illumination we are getting good results. We simulate this CIGS solar cell model by varying various physical parameters of CIGS like thickness, carrier density, band gap and temperature.

Ionic electrodeposition of II-VI and III-V compounds. III. Computer simulation of quasi-rest potentials for M/sub 1/X/sub 1/ compounds analogous to CdTe

International Nuclear Information System (INIS)

Engelken, R.D.

1987-01-01

The quasi-rest potential (QRP) has been proposed as a key quantity in characterizing compound semiconductor (e.g. CdTe) electrodeposition. This article expands the modeling/simulation representative of Cd/sub x/Te in chemical equilibrium to calculate two ''QRP's'': E/sub M/1/sub /, the mixed potential occurring immediately after current interruption and before any relaxation in double layer ion concentration and significant ion exchange/surface stoichiometry change occur, and E/sub M/2/sub /, another mixed potential occurring after the double layer ion concentrations have relaxed to their bulk values but still before any significant surface composition change occurs. Significant predictions include existence of a dramatic negative transition in QRP, with negative-going deposition potential, centered on the potential of perfect stoichiometry (PPS), inequality, in general, between the PPS and E/sub M/1/sub / unless the deposit remains in equilibrium with the electrolyte (no ion exchange at open circuit), negligible sensitivity of QRP-E curves to the activity coefficient parameter implying the importance of the PPS in characterizing compound deposition, and disappearance of the transition structure for sufficiently positive Gibbs free energies

Aluminum-doped zinc oxide films as transparent conductive electrode for organic light-emitting devices

International Nuclear Information System (INIS)

Jiang, X.; Wong, F.L.; Fung, M.K.; Lee, S.T.

2003-01-01

Highly transparent conductive, aluminum-doped zinc oxide (ZnO:Al) films were deposited on glass substrates by midfrequency magnetron sputtering of metallic aluminum-doped zinc target. ZnO:Al films with surface work functions between 3.7 and 4.4 eV were obtained by varying the sputtering conditions. Organic light-emitting diodes (OLEDs) were fabricated on these ZnO:Al films. A current efficiency of higher than 3.7 cd/A, was achieved. For comparison, 3.9 cd/A was achieved by the reference OLEDs fabricated on commercial indium-tin-oxide substrates

Understanding arsenic incorporation in CdTe with atom probe tomography

Energy Technology Data Exchange (ETDEWEB)

Burton, G. L.; Diercks, D. R.; Ogedengbe, O. S.; Jayathilaka, P. A. R. D.; Edirisooriya, M.; Myers, T. H.; Zaunbrecher, K. N.; Moseley, J.; Barnes, T. M.; Gorman, B. P.

2018-08-01

Overcoming the open circuit voltage deficiency in Cadmium Telluride (CdTe) photovoltaics may be achieved by increasing p-type doping while maintaining or increasing minority carrier lifetimes. Here, routes to higher doping efficiency using arsenic are explored through an atomic scale understanding of dopant incorporation limits and activation in molecular beam epitaxy grown CdTe layers. Atom probe tomography reveals spatial segregation into nanometer scale clusters containing > 60 at% As for samples with arsenic incorporation levels greater than 7-8 x 10^17 cm-3. The presence of arsenic clusters was accompanied by crystal quality degradation, particularly the introduction of arsenic-enriched extended defects. Post-growth annealing treatments are shown to increase the size of the As precipitates and the amount of As within the precipitates.

Novel optical properties of CdS:Zn rocksalt system (a theoretical study)

Science.gov (United States)

Khan, M. Junaid Iqbal; Nauman Usmani, M.; Kanwal, Zarfishan

2017-11-01

In present computational study, we focus on optical properties of Zn doped CdS for 1  ×  1  ×  2 and 2  ×  2  ×  2 supercell configurations. Cd atoms are substituted with Zn atoms and results for optical properties demonstrate different trends due to interaction of Zn with S atoms. The study has been performed by PBE-GGA approach using Wien2K within framework of DFT. TDOS and PDOS represent that S-3p states are responsible for conduction. For large supercell configuration, a tremendous change in optical properties has been observed due to different bonding. Optical absorption tends to increase in visible range which supports candidacy of Zn doped CdS for enhanced optoelectronic and nanotechnology applications.

Raman Spectroscopy of SiO{sub 2}–Na{sub 2}O–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3} glass doped with Nd{sup 3+} and CdS nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Serqueira, E.O.; Dantas, N.O. [Laboratório de Novos Materiais Isolantes e Semicondutores (LNMIS), Instituto de Física, Universidade Federal de Uberlândia, Uberlândia, MG 38400-902 (Brazil); Anjos, V. [Grupo de Espectroscopia de Materiais, Departamento de Física, ICE – UFJF, Campus Universitário, Juiz de Fora, MG 36036-330 (Brazil); Bell, M.J.V., E-mail: mjvbell@yahoo.com.br [Grupo de Espectroscopia de Materiais, Departamento de Física, ICE – UFJF, Campus Universitário, Juiz de Fora, MG 36036-330 (Brazil)

2014-01-05

Highlights: • The formation of CdS nanocrystals in the glassy host is shown by Raman measurements. • Nd{sub 2}O{sub 3} modifies the growth of CdS nanocrystals in the SNAB glass. • Nd{sup 3+} ions are not incorporated inside the semiconductor nanocrystals. -- Abstract: We report the Raman spectroscopic characterization of a SNAB glass system doped with neodymium and CdS nanocrystals and fabricated by the fusion process. Raman spectra revealed CdS nanocrystals in the glass host and bands associated with Si–O vibrational modes with five structural configurations, boroxol modes of B{sub 2}O{sub 3}, Al–O and Cd–S vibrational modes. Additionally, Nd{sub 2}O{sub 3} modifies the growth of CdS nanocrystals in the SNAB glass and Nd{sup 3+} ions are not incorporated inside the semiconductor nanocrystals.

Hyperfine interactions in {sup 111}Cd-doped lutetium sesquioxide

Energy Technology Data Exchange (ETDEWEB)

Errico, L.A.; Renteria, M.; Bibiloni, A.G.; Requejo, F.G. [Universidad Nacional de La Plata, Programa TENAES (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas (Argentina)

1999-09-15

We report here first Perturbed Angular Correlation (PAC) results of the electric field gradient (EFG) characterisation at {sup 111}Cd impurities located at both non-equivalent cation sites of the bixbyite structure of Lutetium sesquioxide, between room temperature (RT) and 1273 K. The comparison with results coming from a systematic {sup 111}Cd PAC study in bixbyites and with point-charge model (PCM) predictions shows the presence of a trapped defect at RT in the neighbourhood of the asymmetric cation site, which is completely removed at T > 623 K. The anomalous EFG temperature dependence in Lu{sub 2}O{sub 3} can be described in the frame of a 'two-state' model with fluctuating interactions, which enables the experimental determination of the acceptor energy level introduced by the Cd impurity in the band-gap of the semiconductor and the estimation of the oxygen vacancy density in the sample.

Visible-light sensitization of TiO2 photocatalysts via wet chemical N-doping for the degradation of dissolved organic compounds in wastewater treatment: a review

Science.gov (United States)

Zhang, Wei; Jia, Baoping; Wang, Qiuze; Dionysiou, Dionysois

2015-05-01

Increased pollution of ground and surface water and emerging new micropollutants from a wide variety of industrial, municipal, and agricultural sources has increased demand on the development of innovative new technologies and materials whereby challenges associated with the provision of safe potable water can be addressed. Heterogeneous photocatalysis using visible-light sensitized TiO2 photocatalysts has attracted a lot of attention as it can effectively remove dissolved organic compound in water without generating harmful by-products. On this note, recent progress on visible-light sensitive TiO2 synthesis via wet chemical N-doping method is reviewed. In a typical visible-light sensitive TiO2 preparation via wet chemical methods, the chemical (e.g., N-doping content and states) and morphological properties (e.g., particle size, surface area, and crystal phase) of TiO2 in as-prepared resultants are sensitively dependent on many experimental variables during the synthesis. This has also made it very difficult to provide a universal guidance at this stage with a certainty for each variable of N-doping preparation. Instead of one-factor-at-a-time style investigation, a statistically valid parameter optimization investigation for general optima of photocatalytic activity will be certainly useful. Optimization of the preparation technique is envisaged to be beneficial to many environmental applications, i.e., dissolved organic compounds removal in wastewater treatment.

Visible-light sensitization of TiO2 photocatalysts via wet chemical N-doping for the degradation of dissolved organic compounds in wastewater treatment: a review

International Nuclear Information System (INIS)

Zhang, Wei; Jia, Baoping; Wang, Qiuze; Dionysiou, Dionysois

2015-01-01

Increased pollution of ground and surface water and emerging new micropollutants from a wide variety of industrial, municipal, and agricultural sources has increased demand on the development of innovative new technologies and materials whereby challenges associated with the provision of safe potable water can be addressed. Heterogeneous photocatalysis using visible-light sensitized TiO 2 photocatalysts has attracted a lot of attention as it can effectively remove dissolved organic compound in water without generating harmful by-products. On this note, recent progress on visible-light sensitive TiO 2 synthesis via wet chemical N-doping method is reviewed. In a typical visible-light sensitive TiO 2 preparation via wet chemical methods, the chemical (e.g., N-doping content and states) and morphological properties (e.g., particle size, surface area, and crystal phase) of TiO 2 in as-prepared resultants are sensitively dependent on many experimental variables during the synthesis. This has also made it very difficult to provide a universal guidance at this stage with a certainty for each variable of N-doping preparation. Instead of one-factor-at-a-time style investigation, a statistically valid parameter optimization investigation for general optima of photocatalytic activity will be certainly useful. Optimization of the preparation technique is envisaged to be beneficial to many environmental applications, i.e., dissolved organic compounds removal in wastewater treatment

Bond-versus-site doping models for off-chain-doped Haldane-gap system Y2BaNiO5

International Nuclear Information System (INIS)

Lou Jizhong; Qin Shaojin; Su Zhaobin; Yu Lu

1998-09-01

Using the density matrix renormalization-group technique, we calculate the impurity energy levels for two different effective models of off-chain doping for quasi-one-dimensional Heisenberg chain compound Y 2 BaNiO 5 : ferromagnetic bond doping and antiferromagnetic site spin-1/2 doping. Thresholds of the impurity strength for the appearance of localized states are found for both models. However, the ground-state and low-energy excitations for weak impurity strength are different for these two models and the difference can be detected by experiments. (author)

Growth of highly transparent Cd{sub x}Zn{sub 1−x}O (CZO) thin films: Structural and optical studies

Energy Technology Data Exchange (ETDEWEB)

Gautam, Naina, E-mail: nainagtm@gmail.com [Department of Electronic Science, University of Delhi South Campus, New Delhi 110023 (India); Singh, Fouran, E-mail: fouran@gmail.com [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Gautam, Subodh K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Singh, R.G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi 110043 (India); Ojha, S. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Kapoor, A. [Department of Electronic Science, University of Delhi South Campus, New Delhi 110023 (India)

2015-11-25

The deposition of Cd{sub x}Zn{sub 1−x}O thin films with different cadmium concentrations i.e., x = 0.0, 0.05, 0.20 by sol–gel spin coating is reported. The doping fraction of Cd in ZnO films was measured by Rutherford backscattering spectrometry (RBS), while the surface morphology was studied by scanning electron microscopy (SEM). Grazing incidence X-ray diffraction (GIXRD) study was carried out for the structural investigations and reveals hexagonal wurtzite structure with polycrystalline nature. The various structural parameters are calculated including the lattice constants ‘a’ and ‘c’, stress (σ), strain (ε) and internal parameter (u). For x = 0.20 Cd content, the formation of secondary phase of the cubic CdO at 33.12° (111) and 38.41° (200) is observed and this is further confirmed by micro-Raman studies, where the TO mode emerges at ∼261.5 cm{sup −1}. The basic wurtzite structure is maintained as ‘c/a’ ratio and internal parameter ‘u’ found to be closer to the ideal values. All the films are found to be highly transparent in the visible region and a bending of the near band edge (NBE) absorption is observed with Cd doping. It is further confirmed by calculating the Urbach energy (E{sub u}), which is found to be increased from 0.14 eV (for x = 0.0) to 0.26 eV (for x = 0.20) with maximum value for the lightly doped films i.e. x = 0.05. However, the optical band gap is found to decrease from 3.26 eV (for x = 0.0) to 3.08 eV (for x = 0.20). - Highlights: • High transparent Cd{sub x}Zn{sub 1−x}O (CZO) thin films with an average transparency of ∼85% in the visible region. • Band-gap tuning is achieved by Cd doping in ZnO. • Segregation of cubic rock-salt CdO phase upon high doping as confirmed by Micro-Raman and SEM investigations.

Uncooled middle wavelength infrared photoconductors based on (111) and (100) oriented HgCdTe

Science.gov (United States)

Madejczyk, Paweł; Kębłowski, Artur; Gawron, Waldemar; Martyniuk, Piotr; Kopytko, Małgorzata; Stępień, Dawid; Rutkowski, Jarosław; Piotrowski, Józef; Piotrowski, Adam; Rogalski, Antoni

2017-09-01

We present progress in metal organic chemical vapor deposition (MOCVD) growth of (100) HgCdTe epilayers achieved recently at the Institute of Applied Physics, Military University of Technology and Vigo System S.A. It is shown that MOCVD technology is an excellent tool for the fabrication of different HgCdTe detector structures with a wide range of composition, donor/acceptor doping, and without post grown ex-situ annealing. Surface morphology, residual background concentration, and acceptor doping efficiency are compared in (111) and (100) oriented HgCdTe epilayers. At elevated temperatures, the carrier lifetime in measured p-type photoresistors is determined by Auger 7 process with about one order of magnitude difference between theoretical and experimental values. Particular progress has been achieved in the growth of (100) HgCdTe epilayers for medium wavelength infrared photoconductors operated in high-operating temperature conditions.

Magnetic properties of Eu doped BiGdO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Nithya, R., E-mail: nithya@igcar.gov.in; Yadagiri, K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, 603 102, TN (India); Shukla, Neeraj [UGC-DAE-CSR Kalpakkam Node, Kokilamedu-603 104, TN (India)

2016-05-23

Bulk Bismuth Gadolinium Oxide, BiGdO{sub 3} and Eu doped BiGdO{sub 3} compounds were synthesized by the conventional solid state reaction in air. Phase formation of these compounds was tracked using powder X-ray characterization technique since single phase formation was found to be sensitive to thermal treatment parameters such as cooling and heating rates. Analysis of X-ray diffraction patterns revealed cubic structure with Pm-3m symmetry. An antiferromagnetic transition around 3.8 K was observed in the pristine compound whereas doped samples showed paramagnetic nature in the whole measured temperature range.

The electric field gradient at 111Cd in ZrZn2 in the samples prepared at 8 GPa

International Nuclear Information System (INIS)

Sorokin, A.A.; Ryasny, G.K.; Komissarova, B.A.; Tsvyashchenko, A.V.; Fomichova, L.N.

2005-01-01

Full text: The perturbed angular correlation (PAC) measurements with the 111 In- 111 Cd nuclear probe embedded into the lattice of the cubic (C15) Laves compound in ZrZn 2 showed that 111 Cd nuclei experienced an axially symmetric electric quadrupole interaction with a frequency v Q = 133.7 MHz at room temperature. The samples were synthesized and doped with the probe at a pressure 8 GPa. The temperature dependence of v Q was shown to be linear: v Q (T) = 147(1 - 0.033 T) MHz. As long as the value of v Q at room temperature was very close to that known for 111 Cd in the hcp lattice of Zn (133.5 MHz), we have checked if it could be assigned to the residual Zn metal in the sample. For the Zn sample melted and doped with 111 In at 8 GPa we have obtained v Q = 117.3 MHz at 300 K and 127 MHz at 80 K - both values considerably lower than that for 111 In-doped Zn samples prepared at an ambient pressure. For the sample re-melted after synthesis at high pressure in the low-pressure Ar atmosphere we have obtained v Q = 131(1) MHz. It can be noted that the value v Q (Zn) at 300 K is close to that obtained earlier in measurements with the sample at a pressure of ≅2 GPa It may be considered as an evidence of incomplete relaxation (at room temperature) of the Zn lattice after melting and quenching at 8 GPa. In the case of Zn sharp precession patterns with zero non-axiality parameter and very low damping were observed only with freshly prepared, or held at LN temperature samples, and after two days exposure at room temperature they suffered a considerable distortion. These data, and the fact that v Q (T) in Zn is known to follow the T 3/2 law, allow us to attribute the v Q value quoted above to 111 Cd nuclei at the substitutional sites with tetrahedral symmetry in the Zn sublattice of ZrZn 2

Improved performance of quantum dot light emitting diode by modulating electron injection with yttrium-doped ZnO nanoparticles

Science.gov (United States)

Li, Jingling; Guo, Qiling; Jin, Hu; Wang, Kelai; Xu, Dehua; Xu, Yongjun; Xu, Gang; Xu, Xueqing

2017-10-01

In a typical light emitting diode (QD-LED), with ZnO nanoparticles (NPs) serving as the electron transport layer (ETL) material, excessive electron injection driven by the matching conduction band maximum (CBM) between the QD and this oxide layer usually causes charge imbalance and degrades the device performance. To address this issue, the electronic structure of ZnO NPs is modified by the yttrium (Y) doping method. We demonstrate that the CBM of ZnO NPs has a strong dependence on the Y-doping concentration, which can be tuned from 3.55 to 2.77 eV as the Y doping content increases from 0% to 9.6%. This CBM variation generates an enlarged barrier between the cathode and this ZnO ETL benefits from the modulation of electron injection. By optimizing electron injection with the use of a low Y-doped (2%) ZnO to achieve charge balance in the QD-LED, device performance is significantly improved with maximum luminance, peak current efficiency, and maximal external quantum efficiency increase from 4918 cd/m2, 11.3 cd/A, and 4.5% to 11,171 cd/m2, 18.3 cd/A, and 7.3%, respectively. This facile strategy based on the ETL modification enriches the methodology of promoting QD-LED performance.

High-efficiency white organic light-emitting devices with a non-doped yellow phosphorescent emissive layer

Energy Technology Data Exchange (ETDEWEB)

Zhao Juan; Yu Junsheng, E-mail: jsyu@uestc.edu.cn; Hu Xiao; Hou Menghan; Jiang Yadong

2012-03-30

Highly efficient phosphorescent white organic light-emitting devices (PHWOLEDs) with a simple structure of ITO/TAPC (40 nm)/mCP:FIrpic (20 nm, x wt.%)/bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2} Prime ] iridium (acetylacetonate) (tbt){sub 2}Ir(acac) (y nm)/Bphen (30 nm)/Mg:Ag (200 nm) have been developed, by inserting a thin layer of non-doped yellow phosphorescent (tbt){sub 2}Ir(acac) between doped blue emitting layer (EML) and electron transporting layer. By changing the doping concentration of the blue EML and the thickness of the non-doped yellow EML, a PHWOLED comprised of higher blue doping concentration and thinner yellow EML achieves a high current efficiency of 31.7 cd/A and Commission Internationale de l'Eclairage coordinates of (0.33, 0.41) at a luminance of 3000 cd/m{sup 2} could be observed. - Highlights: Black-Right-Pointing-Pointer We introduce a simplified architecture for phosphorescent white organic light-emitting device. Black-Right-Pointing-Pointer The key concept of device fabrication is combination of doped blue emissive layer (EML) with non-doped ultra-thin yellow EML. Black-Right-Pointing-Pointer Doping concentration of the blue EML and thickness of the yellow EML are sequentially adjusted. Black-Right-Pointing-Pointer High device performance is achieved due to improved charge carrier balance as well as two parallel emission mechanisms in the EMLs.

Phosphorescent Molecularly Doped Light-Emitting Diodes with Blended Polymer Host and Wide Emission Spectra

Directory of Open Access Journals (Sweden)

Jun Wang

2013-01-01

Full Text Available Stable green light emission and high efficiency organic devices with three polymer layers were fabricated using bis[2-(4′-tert-butylphenyl-1-phenyl-1H-benzoimidazole-N,C2′] iridium(III (acetylacetonate doped in blended host materials. The 1 wt% doping concentration showed maximum luminance of 7841 cd/cm2 at 25.6 V and maximum current efficiency of 9.95 cd/A at 17.2 V. The electroluminescence spectra of devices indicated two main peaks at 522 nm and 554 nm coming from phosphor dye and a full width at half maximum (FWHM of 116 nm. The characteristics of using blended host, doping iridium complex, emission spectrum, and power efficiency of organic devices were investigated.

Structure and optical properties of GaSe-CdSe composites driven by Cd intercalation in GaSe lamellar crystals

International Nuclear Information System (INIS)

Caraman, Iuliana; Kantser, Valeriu; Evtodiev, Igor; Untila, Dumitru; Dmitroglo, Liliana; Leontie, Liviu; Arzumanyan, Grigory

2015-01-01

A new composite material composed of GaSe and CdSe has been obtained by treatment of GaSe single-crystal lamellas in Cd vapors at temperatures of 773-853 K and intercalation of Cd interlayers. The structure and optical properties of the GaSe-CdSe composite material have been studied. The content of CdSe crystallites was found to grow with increasing treatment temperature or with increasing duration of treatment at a constant temperature. Analysis of XRD, PL, XPS, AFM, and Raman patterns has shown that the heterogeneous composite composed of micro and nanocrystallites of CdSe in GaSe can be obtained by Cd intercalation in a temperature range of 753-853 K. On the basis of Raman spectrum, the vibrational modes of the composite have been identified. The PL of these materials contains emission bands of free and bound excitons, donor-acceptor bands, and bands of recombination via impurity levels. The PL emission spectra measured at a temperature of 78 and 300 K for the composites result from the overlapping of the emission bands of the components of GaSe doped with Cd and the CdSe crystallites. (authors)

In situ synthesis of CdS/CdWO4/WO3 heterojunction films with enhanced photoelectrochemical properties

Science.gov (United States)

Zhan, Faqi; Li, Jie; Li, Wenzhang; Yang, Yahui; Liu, Wenhua; Li, Yaomin

2016-09-01

CdS/CdWO4/WO3 heterojunction films on fluorine-doped tin oxide (FTO) substrates are for the first time prepared as an efficient photoanode for photoelectrochemical (PEC) hydrogen generation by an in situ conversion process. The samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet visible spectrometry (UV-vis) and X-ray photoelectron spectroscopy (XPS). The CdS hollow spheres (∼80 nm) sensitized WO3 plate film with a CdWO4 buffer-layer exhibits increased visible light absorption and a significantly improved photoelectrochemical performance. The photocurrent density at 0 V (vs. Ag/AgCl) of the CdS/CdWO4/WO3 anode is ∼3 times higher than that of the CdWO4/WO3 anode, and ∼9 times higher than that of pure WO3 under illumination. The highest incident-photon-to-current-efficiency (IPCE) value increased from 16% to 63% when the ternary heterojunction was formed. This study demonstrates that the synthesis of ternary composite photocatalysts by the in situ conversion process may be a promising approach to achieve high photoelectric conversion efficiency.

Superconductivity induced by doping Rh in CaFe2-xRhxAs2

International Nuclear Information System (INIS)

Qi Yanpeng; Wang Lei; Gao Zhaoshun; Wang Dongliang; Zhang Xianping; Wang Chunlei; Yao Chao; Ma Yanwei

2011-01-01

In this paper, we report the synthesis of iron-based superconductors CaFe 2-x Rh x As 2 using a one-step solid state reaction method that crystallizes in the ThCr 2 Si 2 -type structure with a space group I4/mmm. The systematic evolution of the lattice constants demonstrates that the Fe ions are successfully replaced by the Rh. By increasing the doping content of Rh, the spin-density-wave (SDW) transition in the parent compound is suppressed and superconductivity emerges. The maximum superconducting transition temperature is found at 18.5 K with a doping level of x=0.15. The temperature dependence of dc magnetization confirms superconducting transitions at around 15 K. The general phase diagram was obtained and found to be similar to the case of the Rh-doping Sr122 system. Our results explicitly demonstrate the feasibility of inducing superconductivity in Ca122 compounds by higher d-orbital electron doping; however, different Rh-doping effects between FeAs122 compounds and FeAs1111 systems still remains an open question.

Thermodynamic evaluation of liquid Cd cathode containing U and Pu

International Nuclear Information System (INIS)

Kurata, Masaki; Uozumi, Koichi; Kato, Tetsuya; Iizuka, Masatoshi

2009-01-01

In our previous study, a mixture of U and Pu was recovered in liquid Cd cathode from molten salt under various conditions of the U:Pu ratio. Two important things were observed. The first was that three kinds of precipitated phase had been detected in the saturated liquid Cd cathode, such as a U metal and two kinds of U-Pu-Cd compound. The compositions of the compounds were roughly (U+Pu):Cd=1:11 and (U+Pu):Cd=1:6. The second was that the U metal had selectively precipitated in the saturated liquid Cd cathode under the condition that the U:Pu ratio is higher than about 0.8 in the liquid Cd phase. In the present study, phase diagrams were evaluated by the CALPHAD method on the liquid Cd cathode containing U and Pu. The U-Pu-Cd compounds were modeled as MCd 11 -type and MCd 6 -type, respectively, based on the reported binary phase diagrams of U-Cd and Pu-Cd. The calculated result reasonably agreed with the experimental observations. The variations in the U and Pu activities were estimated along with the U:Pu ratio, which is related to the precipitation of various phases in the liquid Cd cathode. (author)

Density Functional Investigation of Graphene Doped with Amine-Based Organic Molecules

Directory of Open Access Journals (Sweden)

Yeun Hee Hwang

2015-01-01

Full Text Available To improve the electronic properties of graphene, many doping techniques have been studied. Herein, we investigate the electronic and molecular structure of doped graphene using density functional theory, and we report the effects of amine-based benzene dopants adsorbed on graphene. Density functional theory (DFT calculations were performed to determine the role of amine-based aromatic compounds in graphene doping. These organic molecules bind to graphene through long-range interactions such as π-π interactions and C-H⋯π hydrogen bonding. We compared the electronic structures of pristine graphene and doped graphene to understand the electronic structure of doped graphene at the molecular level. Also, work functions of doped graphene were obtained from electrostatic potential calculations. A decrease in the work function was observed when the amine-based organic compounds were adsorbed onto graphene. Because these systems are based on physisorption, there was no obvious band structure change at point K at the Fermi level after doping. However, the amine-based organic dopants did change the absolute Fermi energy levels. In this study, we showed that the Fermi levels of the doped graphene were affected by the HOMO energy level of the dopants and by the intermolecular charge transfer between the adsorbed molecules and graphene.

Structural, elastic and magnetic properties of Mn and Sb doped chromium nitride – An ab initio study

Energy Technology Data Exchange (ETDEWEB)

Ikram Un Nabi Lone; Sheik Sirajuddeen M Mohamed, E-mail: msheiksiraj@bsauniv.ac.in; Shameem Banu, I.B.; Sathik Basha, S.

2017-05-01

Structural, magnetic and elastic properties of Mn and Sb doped CrN were investigated by the electronic band structure calculations using Full Potential Linear Augmented Plane Wave (FP-LAPW) method. The host compound CrN was doped with Mn and Sb separately, in the doping concentration of 12.5% to replace Cr atoms. The introduction of Mn and Sb atoms replacing the Cr atoms does not change the structural stability of the compound. The changes in magnetic and elastic properties were investigated and compared in GGA and GGA+U methods. The doped CrN undergoes a relative increase in the magnetic order with the substitution of Mn and Sb atoms. In GGA method, the magnetic moments are found to be greater in Mn doped CrN than that found in Sb doped Cr{sub 0.875}NSb{sub 0.125}. When doped with Sb, the elastic moduli such as Young’s modulus, bulk modulus and rigidity modulus show a relative increase in comparison with that in Mn doped CrN. Using Hubbard model in GGA+U method, both the magnetic and elastic properties increase in Mn and Sb doped compounds. - Highlights: • Mn and Sb doped Chromium Nitride. • Structural properties. • Magnetic properties. • Elastic properties.

Semiconductor CdF₂:Ga and CdF₂:In Crystals as Media for Real-Time Holography

Directory of Open Access Journals (Sweden)

Alexander E. Angervaks

2012-05-01

Full Text Available Monocrystalline cadmium fluoride is a dielectric solid that can be converted into a semiconductor by doping with donor impurities and subsequent heating in the reduction atmosphere. For two donor elements, Ga and In, the donor (“shallow” state is a metastable one separated from the ground (“deep” state by a barrier. Photoinduced deep-to-shallow state transition underlies the photochromism of CdF₂:Ga and CdF₂:In. Real-time phase holograms are recorded in these crystals capable of following up optical processes in a wide frequency range. The features of photochromic transformations in CdF₂:Ga and CdF₂:In crystals as well as holographic characteristics of these media are discussed. Exemplary applications of CdF₂-based holographic elements are given.

Physicochemical, Spectral, and Biological Studies of Mn(II, Cu(II, Cd(II, Zr(OH2(IV, and UO2(VI Compounds with Ligand Containing Thiazolidin-4-one Moiety

Directory of Open Access Journals (Sweden)

Dinesh Kumar

2014-01-01

Full Text Available The Schiff base (I upon reacting with mercaptoacetic acid in dry benzene undergoes cyclization and forms N-(2-carbamoylthienyl-C-(3′-carboxy-2′-hydroxyphenylthiazolidin-4-one, LH3 (II. A MeOH solution of II reacts with Mn(II, Cu(II, Cd(II, Zr(OH2(IV, and UO2(VI ions and forms the coordination compounds, [Mn(LH(MeOH2], [Cu(LH]2, [Cd(LH], [Zr(OH2(OAc2(LH3], and [UO2(NO3(LH2(MeOH]. The compounds have been characterized on the basis of elemental analyses, molar conductance, molecular weight, spectral (IR, reflectance, and EPR studies and magnetic susceptibility measurements. LH3 behaves as a neutral tridentate ONS donor ligand in [Zr(OH2(OAc2(LH3], monobasic tridentate ONS donor ligand in [UO2(NO3(LH2(MeOH], dibasic tridentate OOS donor ligand in [Cu(LH]2 and dibasic tetradentate OONO donor ligand in [Mn(LH(MeOH2] and [Cd(LH]. [Cu(LH]2 is dimer, while all other compounds are monomers in diphenyl. A square-planar structure for [Cu(LH]2, a tetrahedral structure for [Cd(LH], an octahedral structure for [Mn(LH(MeOH2], a pentagonal-bipyramidal structure for [Zr(OH2(OAc2(LH3], and an eight-coordinate structure for [UO2(NO3(LH2(MeOH] are proposed. The ligand (II and its compounds show antibacterial activities towards E. coli. (Gram negative and S. aureus (Gram positive.

Cannabis in sport: anti-doping perspective.

Science.gov (United States)

Huestis, Marilyn A; Mazzoni, Irene; Rabin, Olivier

2011-11-01

Since 2004, when the World Anti-Doping Agency assumed the responsibility for establishing and maintaining the list of prohibited substances and methods in sport (i.e. the Prohibited List), cannabinoids have been prohibited in all sports during competition. The basis for this prohibition can be found in the World Anti-Doping Code, which defines the three criteria used to consider banning a substance. In this context, we discuss the potential of cannabis to enhance sports performance, the risk it poses to the athlete's health and its violation of the spirit of sport. Although these compounds are prohibited in-competition only, we explain why the pharmacokinetics of their main psychoactive compound, Δ(9)-tetrahydrocannabinol, may complicate the results management of adverse analytical findings. Passive inhalation does not appear to be a plausible explanation for a positive test. Although the prohibition of cannabinoids in sports is one of the most controversial issues in anti-doping, in this review we stress the reasons behind this prohibition, with strong emphasis on the evolving knowledge of cannabinoid pharmacology.

Observation of the magnetization-step in Gd doped antiperovskite compounds Mn{sub 3}Cu{sub 1−x}Gd{sub x}N (0.15≤x≤0.25)

Energy Technology Data Exchange (ETDEWEB)

Yuan, Quan [Center for Composite Materials and structures, Harbin Institute of Technology, Harbin 150080 (China); Zhang, Xinghong, E-mail: zhangxh@hit.edu.cn [Center for Composite Materials and structures, Harbin Institute of Technology, Harbin 150080 (China); Gao, Tangling [Institute of Petrochemistry, Heilongjiang Academy of Sciences, Harbin 150040 (China); Zhao, Jinggeng [Department of Physics, Harbin Institute of Technology, Harbin 150080 (China); Academy of Fundamental and Interdisciplinary Sciences, Harbin 150080 (China); Han, Jiecai; Zhou, Shanbao [Center for Composite Materials and structures, Harbin Institute of Technology, Harbin 150080 (China); Hu, Chang; Wang, Xianjie [Department of Physics, Harbin Institute of Technology, Harbin 150080 (China); Zhang, Zhihua [School of Materials Science and Engineering, Dalian Jiaotong University, Dalian 116028 (China); Song, Bo, E-mail: songbo@hit.edu.cn [Center for Composite Materials and structures, Harbin Institute of Technology, Harbin 150080 (China); Department of Physics, Harbin Institute of Technology, Harbin 150080 (China); Academy of Fundamental and Interdisciplinary Sciences, Harbin 150080 (China)

2017-04-15

(Gadolinium) Gd-doped antiperovskite compounds Mn{sub 3}Cu{sub 1−x}Gd{sub x}N were synthesized by the conventional solid-state reaction. With increasing Gd concentration, two magnetic transitions appeared at a high Curie temperature (T{sub C1}) corresponding to paramagnetic (PM)-ferromagnetic (FM) transition and a low temperature (T{sub C2}) ascribed to the FM-antiferromagnetic (AFM) transition. The magnetic relaxation results show the formation of a magnetic metastable state after the FM-AFM transition at low temperature (lower than T{sub C2}), forming a novel magnetic-step feature in the process from AFM to FM under a certain magnetic field. - Highlights: • For the first time, a novel magnetization-step features were revealed in Mn-based antiperovskite compounds. • This study not only benefits us to understand the intrinsic origin of two magnetic transitions after Gd doped, but also paves the way for the design and fabrication of new antiperovskite nitrides with different magnetic state and transition temperature for practical applications. • Two-step magnetic transition were induced by doping Gd element. • The process from AFM to FM in the magnetization-step is irreversible, which is different from that observed in other materials.

Doping-assisted low-pressure photoionization mass spectrometry for the real-time detection of lung cancer-related volatile organic compounds.

Science.gov (United States)

Li, Zhen; Xu, Ce; Shu, Jinian; Yang, Bo; Zou, Yao

2017-04-01

Real-time detection of lung cancer-related volatile organic compounds (VOCs) is a promising, non-intrusive technique for lung cancer (LC) prescreening. In this study, a novel method was designed to enhance the detection selectivity and sensitivity of LC-related polar VOCs by dichloromethane (CH 2 Cl 2 ) doping-assisted low-pressure photoionization mass spectrometry (LPPI-MS). Compared with conventional LPPI-MS, CH 2 Cl 2 doping-assisted LPPI-MS boosted the peak intensities of n-propanol, n-pentanal, acetone, and butyl acetate in nitrogen specifically by 53, 18, 16, and 43 times, respectively. The signal intensities of their daughter ions were inhibited or reduced. At relative humidity (RH) of 20%, the sensitivities of n-propanol, n-pentanal, acetone, and butyl acetate detection ranged from 116 to 452 counts/ppbv with a detection time of 10s and R 2 >0.99 for the linear calibration curves. The method was also applicable under higher RH levels of 50% and 90%. Breath samples obtained from 10 volunteers and spiked samples were investigated. Eight-fold enhancements in the signal intensities of polar VOCs were observed in the normal and spiked samples. These preliminary results demonstrate the efficacy of the dichloromethane doping-assisted LPPI technique for the detection of LC-related polar VOCs. Further studies are indispensible to illustrating the detailed mechanism and applying the technique to breath diagnosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Preliminary study of CdTe and CdTe:Cu thin films nanostructures deposited by using DC magnetron sputtering

Energy Technology Data Exchange (ETDEWEB)

Marwoto, Putut; Made, D. P. Ngurah; Sugianto [Departement of Physics, Faculty of Mathematics and Natural Sciences, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah (Indonesia); Wibowo, Edy; Astuti, Santi Yuli; Aryani, Nila Prasetya [Materials Research Group, Laboratory of Thin Film, Department of Physics, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah (Indonesia); Othaman, Zulkafli [Departement of Physics, Universiti Teknologi Malaysia (UTM), Skudai, Johor Bahru (Malaysia)

2013-09-03

Growth and properties of CdTe and CdTe:Cu thin films nanostrucures deposited by using dc magnetron sputtering are reported. Scanning electron microscope (SEM) was used to observe the surface morphologies of the thin films. At growth conditions of 250 °C and 14 W, CdTe films did not yet evenly deposited. However, at growth temperature and plasma power of 325 °C and 43 W, both CdTe and CdTe:Cu(2%) have deposited on the substrates. In this condition, the morphology of the films indicate that the films have a grain-like nanostructures. Grain size diameter of about 200 nm begin to appear on top of the films. Energy Dispersive X-rays spectroscopy (EDX) was used to investigate chemical elements of the Cu doped CdTe film deposited. It was found that the film deposited consist of Cd, Te and Cu elements. XRD was used to investigate the full width at half maximum (FWHM) values of the thin films deposited. The results show that CdTe:Cu(2%) thin film has better crystallographic properties than CdTe thin film. The UV-Vis spectrometer was used to investigate the optical properties of thin films deposited. The transmittance spectra showed that transmittance of CdTe:Cu(2%) film is lower than CdTe film. It was found that the bandgap energy of CdTe and CdTe:Cu(2%) thin films of about 1.48 eV.

A large enhancement of photoinduced second harmonic generation in CdI2--Cu layered nanocrystals.

Science.gov (United States)

Miah, M Idrish

2009-02-12

Photoinduced second harmonic generation (PISHG) in undoped as well as in various Cu-doped (0.05-1.2% Cu) CdI2 nanocrystals was measured at liquid nitrogen temperature (LNT). It was found that the PISHG increases with increasing Cu doping up to approximately 0.6% and then decreases almost to that for the undoped CdI2 for doping higher than approximately 1%. The values of the second-order susceptibility ranged from 0.50 to 0.67 pm V(-1) for the Cu-doped nanocrystals with a thickness of 0.5 nm. The Cu-doping dependence shown in a parabolic fashion suggests a crucial role of the Cu agglomerates in the observed effects. The PISHG in crystals with various nanosizes was also measured at LNT. The size dependence demonstrated the quantum-confined effect with a maximum PISHG for 0.5 nm and with a clear increase in the PISHG with decreasing thickness of the nanocrystal. The Raman scattering spectra at different pumping powers were taken for thin nanocrystals, and the phonon modes originating from interlayer phonons were observed in the spectra. The results were discussed within a model of photoinduced electron-phonon anharmonicity.

Complexes of Zn(2) and Cd(2) with 2-methyl-benzimidazole

Energy Technology Data Exchange (ETDEWEB)

Slyusarenko, K F; Artemenko, M V; Pokhodnya, G A; Kononenko, O.M. (Kievskij Tekhnologicheskij Inst. Pishchevoj Promyshlennosti (Ukrainian SSR))

1978-07-01

Coordination compounds of Zn(2) and Cd(2) salts with 2-methyl-benzimidazole (MBI) of 2MBIxMeX/sub 2/ composition, where Me is Zn (2), Cd (2); X is NO/sub 3//sup -/, CH/sub 3/COO/sup -/, CL/sup -/, Br/sup -/, I/sup -/, 1/2SO/sub 4//sup -2/, as well as acid compounds of (MBIH)/sub 2/(CdX/sub 4/) composition, where X is Cl/sup -/, Br/sup -/, I/sup -/, have been obtained and investigated. The synthetized compounds are of white colour, they are stable in air, soluble in alcohols, decomposed by water. Decomposition temperatures for most of the Cd(2) compounds lie above 250 deg C. Infrared spectra and diffractograms of these compounds have been studied. From the curves of radial distribution of atomic density, the ionic nature of the bonding of halide groups in the complexes has been established.

Coordination compounds of metals with imidazoles and benzimidazoles. [Metals: V, Th, Mo, Cd, rare earths, etc

Energy Technology Data Exchange (ETDEWEB)

Novikova, G A; Molodkin, A K; Kukalenko, S S

1988-12-01

Methods of preparation, composition and structure of UO/sub 2//sup 2+/, Th/sup 4+/, Mo/sup 3+/, Cd/sup 2+/, Ln/sup 3+/ metal ion complexes with imidazoles and benzimidazoles are considered in reviews of native and foreign literature of up to 1985. Complexes are customarily prepared by direct interaction of ligands with inorganic salts in different organic solvents. Complex composition is defined by the nature of complexing metal and inorganic salt anion, ligand volume and basicity, as well as solvent characteristics. Effect of R substituent in imidazole and benzimidazole side chain on composition of coordination compounds is considered.

Extended x-ray absorption fine structure study of arsenic in HgCdTe: p-type doping linked to nonsubstitutional As incorporation in an unknown AsHg8 structure

International Nuclear Information System (INIS)

Biquard, X.; Alliot, I.; Ballet, P.

2009-01-01

An extended x-ray absorption fine structure (EXAFS) investigation has been carried out on arsenic-doped Hg 70 Cd 30 Te samples. The incorporation of atomic arsenic has been achieved using a nonconventional radio-frequency plasma source in a molecular beam epitaxy reactor. Two samples from the same epitaxial wafer have been studied. One underwent a 400 deg. C activation annealing under Hg pressure, leading to n to p-type conversion. In the commonly admitted scenario, this conversion is associated with the annealing-induced migration of As from a Hg site to a Te site. This study shows that this is not the case. Before annealing, As is found to be involved in noncrystalline structures: 50% inside an As 2 Te 3 chalcogenide glass and 50% inside a new AsHg 8 compact structure. After annealing, the As 2 Te 3 chalcogenide glass disappears, 31% of As occupies Hg sites and 69% incorporates inside this new AsHg 8 compact structure that occupies Te sites. The EXAFS results are in excellent agreement with 77 K Hall-effect measurements. The new AsHg 8 structure is found to have an acceptor behavior. Overall, this study provides an entirely new vision of extrinsic p-type doping of HgCdTe as well as the first experimental evidence of As site transfer induced by annealing.

Synthesis, characterization and performance of Cd{sub 1−x}In{sub x}Te compound for solar cell applications

Energy Technology Data Exchange (ETDEWEB)

Shenouda, Atef Y., E-mail: ayshenouda@yahoo.com [Central Metallurgical R and D Institute (CMRDI), Tebbin, P.O. Box 87 Helwan, Cairo 11412 (Egypt); Rashad, Mohamed M. [Central Metallurgical R and D Institute (CMRDI), Tebbin, P.O. Box 87 Helwan, Cairo 11412 (Egypt); Chow, Lee [Department of Physics, University of Central Florida, Orlando, FL 32816 (United States)

2013-06-25

Highlights: ► Cd{sub 1−x}In{sub x}Te samples were synthesized by wet chemical method using NaBH{sub 4} for reduction. ► The band gap energy was achieved to be 1.37 eV with Cd{sub 0.6}In{sub 0.4}Te. ► The highest photovoltaic response was achieved by a power conversion efficiency of 1.89% with Cd{sub 0.6}In{sub 0.4}Te. -- Abstract: Cd{sub 1−x}In{sub x}Te (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) samples have been synthesized chemically using wet chemical method from precursor compounds, CdSO{sub 4}, InCl{sub 3}, and TeCl{sub 4}. The hydroxide form of the solution mixture was obtained by using ammonia solution and the pH of the mixture was adjusted to 9. A suitable amount of NaBH{sub 4} solution was added to reduce the hydroxide phase to the metalloid alloy. The crystal structure has been studied using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements. The 300 °C annealed samples revealed a cubic crystal structure. The morphology of the prepared samples is very fine and the average diameter is between 1 and 2.5 μm. The optical properties were determined using UV–vis–NIR spectrophotometer and band gap energy of 1.37 eV for Cd{sub 0.6}In{sub 0.4}Te was obtained. The best photovoltaic conversion efficiency of 1.89% was obtained for the Cd{sub 0.6}In{sub 0.4}Te sample with a short circuit current density (J{sub sc}) of 15.3 mA cm{sup −2}, an open circuit voltage (V{sub oc}) of 0.668 V, and a filling factor (FF) of 69.31%.

Cd3(MoO4)(TeO3)2: A Polar 3D Compound Containing d10-d0 SCALP-Effect Cations.

Science.gov (United States)

Feng, Yuquan; Fan, Huitao; Zhong, Zhiguo; Wang, Hongwei; Qiu, Dongfang

2016-11-21

The new polar 3D cadmium molybdotellurite Cd 3 (MoO 4 )(TeO 3 ) 2 was obtained by means of a high-temperature solid-state method. Cd 3 (MoO 4 )(TeO 3 ) 2 is a monoclinic crystal system, and it exhibits the polar space group P2 1 (No. 4). The structure of Cd 3 (MoO 4 )(TeO 3 ) 2 can be viewed as a complicated 3D architecture that is composed of distorted CdO n (n = 6, 7) polyhedra, TeO 3 trigonal pyramids, and MoO 4 polyhedra. The compound features the first 3D NCS cadmium molybdotellurite with 1D 4- and 6-MR channels and a polar structure originating from the TeO 3 groups, MoO 4 groups, and displacements of d 10 Cd 2+ cations. The results were further confirmed by calculations of the net polarization. The UV-vis spectrum and thermal properties indicate that Cd 3 (MoO 4 )(TeO 3 ) 2 exhibits a broad transparent region and excellent thermal stability. SHG tests of Cd 3 (MoO 4 )(TeO 3 ) 2 revealed that its response is approximately the same as that of KH 2 PO 4 at the same grain size between 105 and 150 μm and that it is phase-matchable.

The studies of radiation distorations in CdS single crystals by using a proton back-scattering method

International Nuclear Information System (INIS)

Grigor'ev, A.N.; Dikij, N.P.; Matyash, P.P.; Nikolajchuk, L.I.; Pivovar, L.I.

1974-01-01

The radiation defects in semiconducting CdS single crystals induced during doping with 140 keV Na ions (10 15 -2.10 16 ion/cm 2 ) were studied by the orientation dependence of 700 keV proton backscattering. The absence of discrete peaks in the scattered proton eneryg spectra indicates a small contribution of direct scattering at large angles. The defects formed during doping increase the fractionof dechanneled particles, which are then scattered at large anlges. No amorphization of CdS was observed at high Na ion dose 2x10 16 ion/cm 2

Improving superconducting properties of YBCO high temperature superconductor by Graphene Oxide doping

Energy Technology Data Exchange (ETDEWEB)

Dadras, S., E-mail: dadras@alzahra.ac.ir; Dehghani, S.; Davoudiniya, M.; Falahati, S.

2017-06-01

In this research, we report the synthesis and characterization of YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) high temperature superconductor prepared by sol-gel method and doped with Graphene Oxide (GO) in different weight percentages, 0, 0.1, 0.7 and 1 % wt. The x-ray diffraction (XRD) analysis confirms the formation of orthorhombic phase of superconductivity for all the prepared samples. We found that GO doping reduces the crystalline size of the samples. We evaluated the effects of GO doping on the normal state resistivity (ρ), superconducting transition temperature (T{sub c}) and critical current density (J{sub c}). The results show that the GO doping has a positive effect on these properties. Also, the highest J{sub c} is obtained for the 0.7 %wt GO doped YBCO compound that its critical current density is about 15 times more than the J{sub c} of pure one in 0.4 T magnetic field. The scanning electron microscope (SEM) analysis shows that there are better connections between the grains of GO doped samples. - Highlights: • Graphene Oxide doping increased the YBCO critical current density. • Graphene Oxide creates a better connection between the YBCO grains. • The normal resistivity of samples were decreased by GO doping to YBCO compounds. • Graphene Oxide doping has a positive effect on the critical transition temperature.

MOCVD growth of transparent conducting Cd2SnO4 thin films

International Nuclear Information System (INIS)

Metz, A.W.; Poeppelmeier, K.R.; Marks, T.J.; Lane, M.A.; Kannewurt, C.R.

2004-01-01

The first preparation of transparent conducting Cd 2 SnO 4 thin films by a simple MOCVD process is described. As-deposited films using Cd(hfa) 2 (TMEDA) (Figure), at 365 C are found to be highly crystalline with a relatively wide range of grain size of 100-300 nm. XRD indicates a cubic spinel Cd 2 SnO 4 crystal structure and the possible presence of a small amount of CdO. The films exhibit conductivities of 2170 S/cm and a bandgap of 3.3 eV, rivaling those of commercial tin-doped indium oxide. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Microwave studies on the dielectric properties of Sm3+ and Sm3+/CdTe doped sol-gel silica glasses

International Nuclear Information System (INIS)

Mathew, Siby; Rejikumar, P.R.; Yohannan, Jaimon; Mathew, K.T.; Unnikrishnan, N.V.

2008-01-01

Complex permittivity and conductivity studies of Samarium and Samarium/semiconductor cadmium telluride sol-gel silica glass samples were done. We use cavity perturbation technique at S band frequencies using TE 10p Mode. Structural evolution of the matrix on annealing is discussed based on FTIR analysis/XRD power diffraction. In cavity perturbation technique dielectric parameters like complex permittivity and conductivity are determined by measuring changes in resonant frequency due to small perturbation inside the cavity produced by the introduction of the samples. The addition of the semiconductor along with the samarium was found to lower the permittivity, loss factor and conductivity. Variations of permittivity values with annealing temperature find applications in IC Technology, optic fibre communication, etc. The Sm 3+ /CdTe doped glasses can also be used in the fabrication of new and improved materials for microwave electronic circuits and in electromagnetic shielding devices

[Study on two preparation methods for beta-CD inclusion compound of four traditional Chinese medicine volatile oils].

Science.gov (United States)

Li, Hailiang; Cui, Xiaoli; Tong, Yan; Gong, Muxin

2012-04-01

To compare inclusion effects and process conditions of two preparation methods-colloid mill and saturated solution-for beta-CD inclusion compound of four traditional Chinese medicine volatile oils and study the relationship between each process condition and volatile oil physical properties and the regularity of selective inclusion of volatile oil components. Volatile oils from Nardostachyos Radix et Rhizoma, Amomi Fructus, Zingiberis Rhizoma and Angelicaesinensis Radix were prepared using two methods in the orthogonal test. These inclusion compounds by optimized processes were assessed and compared by such methods as TLC, IR and scanning electron microscope. Inclusion oils were extracted by steam distillation, and the components found before and after inclusion were analyzed by GC-MS. Analysis showed that new inclusion compounds, but inclusion compounds prepared by the two processes had differences to some extent. The colloid mill method showed a better inclusion effect than the saturated solution method, indicating that their process conditions had relations with volatile oil physical properties. There were differences in the inclusion selectivity of components between each other. The colloid mill method for inclusion preparation is more suitable for industrial requirements. To prepare volatile oil inclusion compounds with heavy gravity and high refractive index, the colloid mill method needs longer time and more water, while the saturated solution method requires higher temperature and more beta-cyclodextrin. The inclusion complex prepared with the colloid mill method contains extended molecular weight chemical composition, but the kinds of components are reduced.

Synthesis and Structural Studies of Nanocrystalline Cd Zn Fe O

African Journals Online (AJOL)

NICO

The synthesis of Cd0.3Zn0.7Fe2O4 nanoparticles has been achieved by a simple thermal decomposition method from the inorganic ... pure and doped spinel ferrite nanopowders. ... K. Kalimuthu, S.C. Rangasamy and M. Rakkiyasamy,. 91.

Second order magnetic phase transition and scaling analysis in iron doped manganite La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} compounds

Energy Technology Data Exchange (ETDEWEB)

Ginting, Dianta [Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-in 446-701 (Korea, Republic of); Nanto, Dwi [Physics Education, Syarif Hidayatullah State Islamic University, Jakarta 15412 (Indonesia); Denny, Yus Rama [Department of Electrical Engineering, University of Sultan Ageng Tirtayasa, Banten 42435 (Indonesia); Tarigan, Kontan [Department of Mechanical Engineering, Mercu Buana University, Jakarta-Barat, Jakarta 11650 (Indonesia); Hadi, Syamsul [Department of Mechanical Engineering, State Polytechnic of Malang, East Java 65100 (Indonesia); Ihsan, Mohammad [PSTBM-BATAN, Kawasan Puspiptek Serpong, Tangerang Selatan, Banten 15314 (Indonesia); Institute of Electronic Materials, University of Wollongong, Wollongong NSW 2522 (Australia); Rhyee, Jong-Soo, E-mail: jsrhyee@khu.ac.kr [Department of Applied Physics and Institute of Natural Sciences, Kyung Hee University, Yong-in 446-701 (Korea, Republic of)

2015-12-01

We investigated magnetic properties of La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} (x=0.09 and 0.11) compounds in terms of isothermal magnetization analysis and scaling behavior with various critical exponents. From the Landau theory of magnetic phase transition, we found that the paramagnetic to ferromagnetic phase transition in La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3} (x=0.09 and 0.11) compounds is the type of second order magnetic transition (SOMT), which contrary to the first order magnetic transition (FOMT) for low Fe-doped compounds (x<0.09) in previous reports. When we investigate the critical behavior of the compounds near T=T{sub c} by the modified Arrott plot, Kouvel–Fisher plots, and critical isothermal analysis, the estimated critical exponents β, γ, and δ are in between the theoretically predicted values for three-dimensional Heisenberg and mean-field interaction models. It is noteworthy that the scaling relations are obeyed in terms of renormalization magnetization m=ε{sup −β}M(H,ε) and renormalized field h=|ε|{sup β+γ}H. Temperature-dependent effective exponents β{sub eff} and γ{sub eff} correspond to the ones of disordered ferromagnets. It is shown that the magnetic state of the compounds is not fully described by the conventional localized-spin interaction model because the ferromagnetic interaction has itinerant character by increasing Fe-doping concentration. - Highlights: • The ferromagnetic phase transition is of second order in La{sub 0.7}Ca{sub 0.3}Mn{sub 1−x}Fe{sub x}O{sub 3}. • The critical exponents are in between the 3D Heisenberg and mean-field models. • The ferromagnetic interaction becomes more itinerant by Fe-doping.

Comparative investigation of toxicity and bioaccumulation of Cd-based quantum dots and Cd salt in freshwater plant Lemna minor L.

Science.gov (United States)

Modlitbová, Pavlína; Novotný, Karel; Pořízka, Pavel; Klus, Jakub; Lubal, Přemysl; Zlámalová-Gargošová, Helena; Kaiser, Jozef

2018-01-01

The purpose of this study was to determine the toxicity of two different sources of cadmium, i.e. CdCl 2 and Cd-based Quantum Dots (QDs), for freshwater model plant Lemna minor L. Cadmium telluride QDs were capped with two coating ligands: glutathione (GSH) or 3-mercaptopropionic acid (MPA). Growth rate inhibition and final biomass inhibition of L. minor after 168-h exposure were monitored as toxicity endpoints. Dose-response curves for Cd toxicity and EC50 168h values were statistically evaluated for all sources of Cd to uncover possible differences among the toxicities of tested compounds. Total Cd content and its bioaccumulation factors (BAFs) in L. minor after the exposure period were also determined to distinguish Cd bioaccumulation patterns with respect to different test compounds. Laser-Induced Breakdown Spectroscopy (LIBS) with lateral resolution of 200µm was employed in order to obtain two-dimensional maps of Cd spatial distribution in L. minor fronds. Our results show that GSH- and MPA-capped Cd-based QDs have similar toxicity for L. minor, but are significantly less toxic than CdCl 2 . However, both sources of Cd lead to similar patterns of Cd bioaccumulation and distribution in L. minor fronds. Our results are in line with previous reports that the main mediators of Cd toxicity and bioaccumulation in aquatic plants are Cd 2+ ions dissolved from Cd-based QDs. Copyright © 2017 Elsevier Inc. All rights reserved.

Identification and characterization of Cd-induced peptides in Egeria densa (water weed): Putative role in Cd detoxification

International Nuclear Information System (INIS)

Malec, Przemyslaw; Maleva, Maria G.; Prasad, M.N.V.; Strzalka, Kazimierz

2009-01-01

Egeria densa has ability to grow in heavy metal contaminated and polluted bodies of water. Shoots exposed to Cd at concentrations up to 300 μM for 7 days showed a pronounced decrease in chlorophyll a and in total protein concentration. Thiol-containing compounds and low-molecular-weight polypeptides were detected in Cd-treated plant extracts by gel filtration chromatography. Two Cd-binding fractions, a thiol-enriched fraction and a non-thiol fraction with a lower molecular weight were identified in extracts by gel filtration. The main fraction of thiol-containing polypeptide, purified by gel filtration and anion-exchange chromatography had a molecular weight of ∼10 kDa. This peptide was characterized by a broad absorption band specific to mercaptide bonds and Cd-sensitive fluorescence emission of aromatic amino acid residues. Our results indicate that cadmium exposure of plants resulted in both a formation of thiol-enriched cadmium complexing peptides and a synthesis of low-molecular-weight metal chelators. The putative role of these compounds in Cd detoxification is discussed.

Mid-infrared emissions of Pr{sup 3+}-doped GeS{sub 2}–Ga{sub 2}S{sub 3}–CdI{sub 2} chalcohalide glasses

Energy Technology Data Exchange (ETDEWEB)

Lu, Chunfeng [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and precision Mechanics, Chinese Academy of Science (CAS), Xi’an, Shaanxi 710119 (China); Guo, Haitao, E-mail: guoht_001@opt.ac.cn [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and precision Mechanics, Chinese Academy of Science (CAS), Xi’an, Shaanxi 710119 (China); Xu, Yantao; Hou, Chaoqi; Lu, Min [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and precision Mechanics, Chinese Academy of Science (CAS), Xi’an, Shaanxi 710119 (China); He, Xin [School of Applied Physics and Materials, Wuyi University, Jiangmen, Guangdong 529020 (China); Wang, Pengfei; Li, Weinan [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and precision Mechanics, Chinese Academy of Science (CAS), Xi’an, Shaanxi 710119 (China); Peng, Bo, E-mail: bpeng@opt.ac.cn [State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and precision Mechanics, Chinese Academy of Science (CAS), Xi’an, Shaanxi 710119 (China)

2014-12-15

Graphical abstract: ∼4.6 μm mid-infrared fluorescence emission from Pr{sup 3+} in the sulfide glass is successfully observed at room temperature excited by a 2.01 μm Tm{sup 3+}:YAG ceramic laser system. - Highlights: • Serial Pr{sup 3+}-doped GeS{sub 2}–Ga{sub 2}S{sub 3}–CdI{sub 2} chalcohalide glasses were synthesized. • ∼4.6 μm mid-infrared fluorescence from Pr{sup 3+} was observed at room temperature. • The compositional dependence of luminescence properties was studied. • Radiative properties have been determined using the Judd–Ofelt theory. - Abstract: For elucidation of the glass composition’s influence on the spectroscopic properties in the chalcohalide system and the discovery of a new material for applications in mid-infrared fiber-lasers, a serial Pr{sup 3+}-doped (100 − x)(0.8GeS{sub 2}·0.2Ga{sub 2}S{sub 3})xCdI{sub 2} (x = 5, 10, 15 and 20) chalcohalide glasses were prepared. ∼4.6 μm mid-infrared fluorescence emission from Pr{sup 3+} in the sulfide glass is successfully observed at room temperature excited by a 2.01 μm Tm{sup 3+}:YAG ceramic laser system, and the effective line-width of fluorescence band is 106–227 nm. Intense compositional dependence of mid-infrared emissions is found. The radiative rates of Pr{sup 3+} ions in these glasses were calculated by using the Judd–Ofelt theory.

TiO2/ZnS/CdS Nanocomposite for Hydrogen Evolution and Orange II Dye Degradation

Directory of Open Access Journals (Sweden)

Václav Štengl

2011-01-01

Full Text Available TiO2/ZnS/CdS composites for photocatalytic hydrogen production from water were prepared by homogeneous hydrolysis of aqueous solutions mixture of TiOSO4, ZnSO4, and CdSO4 with thioacetamide. Hydrogen evolution was observed in the presence of palladium and platinum nanoparticles deposited on TiO2/ZnS/CdS composites. The morphology was obtained by scanning electron microscopy, the nitrogen adsorption-desorption was used for determination of surface area (BET and porosity. The method of UV-VIS diffuse reflectance spectroscopy was employed to estimate band-gap energies of prepared TiO2/ZnS/CdS nano-composites. The photocatalytic activity of the prepared samples were assessed by photocatalytic decomposition of Orange II dye in an aqueous slurry under UV irradiation at 365 nm wavelength and visible light up to 400 nm wavelength. Doped titanium dioxide by the CdS increased band-gap energy and doping with ZnS increased photocatalytic activity. The best photocatalytic activity for H2 evolution shows sample named TiZnCd7 on surface deposited with palladium, which contains 20.21% TiO2, 78.5% ZnS, and 1.29% CdS.

Topological phase, electronic, magnetic and optical properties of ScPdBi compound with Gd, Np and Cm impurities

Energy Technology Data Exchange (ETDEWEB)

Narimani, Mitra; Nourbakhsh, Zahra, E-mail: z.nourbakhsh@sci.ui.ac.ir

2017-07-15

Highlights: • Gd, Np and Cm impurities induce the magnetic moment in ScPdBi compound. • ScPdBi compound with Gd, Np and Cm impurities has normal band order. • The ε(0) and R(0) increase by increasing the atomic number of X atom. - Abstract: The electronic, magnetic and optical properties of X-doped ScPdBi (X = Gd, Np, Cm) are investigated in the framework of density functional theory. The exchange-correlation potential is treated using generalized gradient approximation with Coulomb interaction parameter. The band order and energy band gap of X-doped ScPdBi are investigated by calculation of band structure. The effect of doping impurity on magnetic properties of ScPdBi compound is studied by calculation of total and partial magnetic moments of X-doped ScPdBi compound. Furthermore, the optical properties of X-doped ScPdBi are calculated and compared in the energy range of 0–25 eV.

CdTe aggregates in KBr crystalline matrix

International Nuclear Information System (INIS)

Bensouici, A.; Plaza, J.L.; Dieguez, E.; Halimi, O.; Boudine, B.; Addala, S.; Guerbous, L.; Sebais, M.

2009-01-01

In this work, we report the experimental results on the fabrication and optical characterization of Czochralski (Cz) grown KBr single crystals doped with CdTe crystallites. The results of the optical absorption have shown two bands, the first one located at 250 nm demonstrates the incorporation of cadmium atoms in the KBr host followed by a partial chemical decomposition of CdTe, the second band located at 585 nm shows an optical response of CdTe aggregates. Photoluminescence spectra at room temperature before annealing showed a band located at 520 nm (2.38 eV), with a blue shift from the bulk gap of 0.82 eV (E g (CdTe)=1.56 eV). While the photoluminescence spectra after annealing at 600 deg. C showed a band situated at 640 nm (1.93 eV), these bands are due to band-to-band transitions of CdTe nanocrystals with a blue shift from the bulk gap at 0.38 eV. Blue shift in optical absorption and photoluminescence spectra confirm nanometric size of dopant. X-ray diffraction (XRD) spectra have shown the incorporation of CdTe aggregates in KBr.

CdTe aggregates in KBr crystalline matrix

Energy Technology Data Exchange (ETDEWEB)

Bensouici, A., E-mail: bensouicia@yahoo.f [Laboratory of Crystallography, Department of Physics, Mentouri-Constantine University, Constantine 25000 (Algeria); Plaza, J.L., E-mail: joseluis.plaza@uam.e [Crystal Growth Laboratory (CGL), Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid (Spain); Dieguez, E. [Crystal Growth Laboratory (CGL), Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Madrid (Spain); Halimi, O.; Boudine, B.; Addala, S. [Laboratory of Crystallography, Department of Physics, Mentouri-Constantine University, Constantine 25000 (Algeria); Guerbous, L. [Centre de recherche nucleaire d' Alger (CRNA), Alger 16000 (Algeria); Sebais, M. [Laboratory of Crystallography, Department of Physics, Mentouri-Constantine University, Constantine 25000 (Algeria)

2009-09-15

In this work, we report the experimental results on the fabrication and optical characterization of Czochralski (Cz) grown KBr single crystals doped with CdTe crystallites. The results of the optical absorption have shown two bands, the first one located at 250 nm demonstrates the incorporation of cadmium atoms in the KBr host followed by a partial chemical decomposition of CdTe, the second band located at 585 nm shows an optical response of CdTe aggregates. Photoluminescence spectra at room temperature before annealing showed a band located at 520 nm (2.38 eV), with a blue shift from the bulk gap of 0.82 eV (E{sub g} (CdTe)=1.56 eV). While the photoluminescence spectra after annealing at 600 deg. C showed a band situated at 640 nm (1.93 eV), these bands are due to band-to-band transitions of CdTe nanocrystals with a blue shift from the bulk gap at 0.38 eV. Blue shift in optical absorption and photoluminescence spectra confirm nanometric size of dopant. X-ray diffraction (XRD) spectra have shown the incorporation of CdTe aggregates in KBr.

Method of doping a semiconductor

International Nuclear Information System (INIS)

Yang, C.Y.; Rapp, R.A.

1983-01-01

A method is disclosed for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient

Color-stable and efficient tandem white organic light-emitting devices using a LiF n-doping layer and a MoO{sub x} p-doping layer as charge generating unit

Energy Technology Data Exchange (ETDEWEB)

Chen, Yu; Wu, Qingyang; Zhang, Zhensong; Yue, Shouzhen; Guo, Runda; Wang, Peng; Wu, Mingzhu; Gou, Changhua; Zhao, Yi, E-mail: yizhao@jlu.edu.cn; Liu, Shiyong

2013-10-31

We have demonstrated color-stable and efficient tandem organic light-emitting devices (OLEDs) using 4,7-diphenyl-1,10-phenanthroline (Bphen):LiF/4,4′,4″-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA):molybdenum oxide (MoO{sub x}) as charge generating unit (CGU), which has the advantages of air stability and ease of fabrication; the working mechanism of Bphen:LiF/m-MTDATA:MoO{sub x} is also discussed through analysis of the electrical and spectral emission properties of tandem devices with different CGUs. The performance of tandem white OLED, comprising blue and yellow phosphorescent EL units, can be improved by optimizing the thickness of Bphen:LiF layer. The device comprised of 30 nm Bphen:LiF layer has a maximum current efficiency of 38.7 cd/A and it can still maintain 24.6 cd/A at the luminance of 10,370 cd/m{sup 2}. Moreover, the Commission Internationale de L'Eclairage (CIE) coordinates of the device are rather stable and the variation is only (± 0.003, ± 0.007) over a wide range of luminance (100–13,000 cd/m{sup 2}). - Highlights: • LiF n-doping layer and MoO{sub x} p-doping layer were used as charge generating units. • The device performance was improved by optimizing the thickness of n-doping layer. • High luminance and efficiency were both achieved at a very low current density. • The device showed rather stable spectra over a wide range of luminance.

Effect of co-doped SnO{sub 2} nanoparticles on photoluminescence of cu-doped potassium lithium borate glass

Energy Technology Data Exchange (ETDEWEB)

Namma, Haydar Aboud; Wagiran, H.; Hussin, R.; Ariwahjoedi, B. [Department of Physics, Universiti Teknologi Malaysia, Skudai 81310, Malaysia and Baghdad College of Economic Sciences University (Iraq); Fundamental and Applied Sciences Department, Universiti Teknologi PETRONAS, 31750 Tronoh (Malaysia)

2012-09-26

The SnO{sub 2} co-doped lithium potassium borate glasses doped with 0.05, 0.10, 0.25 and 0.50 mol% of Cu were synthesized by the melt quenching technique. The SnO{sub 2} co-dope was added to the compounds in the amounts of 0.05, 0.10, and 0.20 mol%. The photoluminescent spectrum for different concentrations of copper was studied. It was observed that the intensity of blue emission (450, 490 nm) varies with concentration mol%. In addition, with different concentration of SnO{sub 2} to 0.10 mol% Cu, the influence of the luminescence has been observed to enhance intensity and shifted to blue and red (490, 535 nm) emissions.

Fabrication of transparent TiO2 nanotube-based photoanodes for CdS/CdTe quantum co-sensitized solar cells

Science.gov (United States)

Gualdrón-Reyes, A. F.; Cárdenas-Arenas, A.; Martínez, C. A.; Kouznetsov, V. V.; Meléndez, A. M.

2017-01-01

In order to fabricate a solar cell, ordered TiO2 nanotube (TNT) arrays were prepared by double anodization. TNT arrays with variable lengths were obtained by changing the duration of the anodizing process of up to 3h. TNT membranes were transferred to indium tin oxide substrates and attached with a B-TiO2 sol. TNT photoanode with the best photoelectrochemical performance was sensitized with CdS by SILAR method. On other hand, CdTe quantum dots prepared via colloidal synthesis were deposited on TNT photoanodes for 2h, 4h and 6h. In addition, TNT/CdS was loaded with CdTe quantum dots for 4 h. Morphology and chemical modification of TiO2 were characterized by FESEM and XPS, while their photoelectrochemical performance was measured by open-circuit photopotential and photovoltammetry under visible light. TiO2 nanotubes grown during 2.5h showed the highest photocurrent due to presence of Ti3+ donor states by N and F co-doping, increasing the number of photogenerated electrons transported to back collector. TNT/CdS/CdTe photoanode reach the highest conversion efficiency under AM 1.5G simulated solar illumination.

First-principles calculations of the magnetic properties of (Cd,Mn)Te nanocrystals

Science.gov (United States)

Echeverría-Arrondo, C.; Pérez-Conde, J.; Ayuela, A.

2009-04-01

We investigate the electronic and magnetic properties of Mn-doped CdTe nanocrystals (NCs) with ˜2nm in diameter which can be experimentally synthesized with Mn atoms inside. Using the density-functional theory, we consider two doping cases: NCs containing one or two Mn impurities. Although the Mnd peaks carry five up electrons in the dot, the local magnetic moment on the Mn site is 4.65μB . It is smaller than 5μB because of the sp-d hybridization between the localized 3d electrons of the Mn atoms and the s - and p -type valence states of the host compound. The sp-d hybridization induces small magnetic moments on the Mn-nearest-neighbor Te sites, antiparallel to the Mn moment affecting the p -type valence states of the undoped dot, as usual for a kinetic-mediated exchange magnetic coupling. Furthermore, we calculate the parameters standing for the sp-d exchange interactions. Conduction N0α and valence N0β are close to the experimental bulk values when the Mn impurities occupy bulklike NCs’ central positions, and they tend to zero close to the surface. This behavior is further explained by an analysis of valence-band-edge states showing that symmetry breaking splits the states and in consequence reduces the exchange. For two Mn atoms in several positions, the valence edge states show a further departure from an interpretation based in a perturbative treatment. We also calculate the d-d exchange interactions |Jdd| between Mn spins. The largest |Jdd| value is also for Mn atoms on bulklike central sites; in comparison with the experimental d-d exchange constant in bulk Cd0.95Mn0.05Te , it is four times smaller.

Electro-optical properties of Cd1-xZnxS films and fabrication of Cd1-xZnxS/InP heterojunctions

International Nuclear Information System (INIS)

Pal, A.K.; Dhar, A.; Mondal, A.; Basak, R.L.; Chaudhuri, S.

1988-01-01

The authors describe Cd 1-x Zn x S films (0 ≤ x ≤ 0.2) characterized by electrical and optical measurements to obtain optimum deposition condition for device fabrication on p-type single crystal InP (Zn doped) with (100) orientation. The devices were studied by I-V, C-V and spectral response measurements

Luminescent MOFs comprising mixed tritopic linkers and Cd(II)/Zn(II) nodes for selective detection of organic nitro compounds and iodine capture

Energy Technology Data Exchange (ETDEWEB)

Rachuri, Yadagiri; Bisht, Kamal Kumar [Analytical Discipline and Centralized Instrument Facility, CSIR–Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, G. B. Marg, Bhavnagar 364002, Gujarat (India); Academy of Scientific and Innovative Research (AcSIR), CSIR–Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, G. B. Marg, Bhavnagar 364002, Gujarat (India); Parmar, Bhavesh [Analytical Discipline and Centralized Instrument Facility, CSIR–Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, G. B. Marg, Bhavnagar 364002, Gujarat (India); Suresh, Eringathodi, E-mail: esuresh@csmcri.org [Analytical Discipline and Centralized Instrument Facility, CSIR–Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, G. B. Marg, Bhavnagar 364002, Gujarat (India); Academy of Scientific and Innovative Research (AcSIR), CSIR–Central Salt and Marine Chemicals Research Institute, Council of Scientific and Industrial Research, G. B. Marg, Bhavnagar 364002, Gujarat (India)

2015-03-15

Two CPs ([Cd{sub 3}(BTC){sub 2}(TIB){sub 2}(H{sub 2}O){sub 4}].(H{sub 2}O){sub 2}){sub n} (1) and ([Zn{sub 3}(BTC){sub 2}(TIB){sub 2}].(H{sub 2}O){sub 6}){sub n} (2) composed of tripodal linkers BTC (1,3,5-benzenetricarboxylate) and TIB (1,3,5-tris(imidazol-1-ylmethyl)benzene) were synthesized via solvothermal route and structurally characterized. Single crystal structural analysis reveals 1 possesses a novel 3D framework structure, whereas 2 represents a previously established compound. Owing to the d{sup 10} configuration of metal nodes and robust 3D frameworks, 1 and 2 exhibit excellent fluorescence properties which have been exploited to sense organic nitro compounds in vapor phase. Compound 1 demonstrates selective sensing of nitromethane over structurally similar methanol with ca. 70 and 43% fluorescence quenching in case of former and later. Similarly, 58% fluorescence quenching was observed in case of nitrobenzene over the structurally resembling toluene for which 30% quenching was observed. Compound 2 did not show any preference for nitro compounds and exhibited comparable fluorescence quenching when exposed to the vapors of nitro or other geometrically resembling organic molecules. Furthermore, adsorption experiments revealed that 1 and 2 can uptake 2.74 and 14.14 wt% molecular iodine respectively in vapor phase which can be released in organic solvents such as hexane and acetonitrile. The maximal iodine uptake in case of 1 and 2 corresponds to 0.15 and 0.80 molecules of iodine per formula unit of respective frameworks. Comprehensive structural description, thermal stability and luminescence behavior for both CPs has also been presented. - Graphical abstract: Two 3D luminescent CPs comprising mixed tripodal ligands have been hydrothermally synthesized and structurally characterized. Iodine encapsulation capacity of synthesized CPs is evaluated and their fluorescence quenching in presence of small organic molecules is exploited for sensing of nitro

Radioluminescence of rare-earth doped aluminum oxide

Energy Technology Data Exchange (ETDEWEB)

Santiago, M.; Molina, P. [Universidad Nacional del Centro de la Provincia de Buenos Aires, Instituto de Fisica Arroyo Seco, Pinto 399, 7000 Tandil (Argentina); Barros, V. S.; Khoury, H. J.; Elihimas, D. R., E-mail: msantiag@exa.unicen.edu.ar [Universidade Federal de Pernambuco, Departamento de Energia Nuclear, Av. Prof. Luiz Freire 1000, Recife, PE 50740-540 (Brazil)

2011-10-15

Carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) is one of the most used radioluminescence (Rl) materials for fiberoptic dosimetry due to its high efficiency and commercial availability. However, this compound presents the drawback of emitting in the spectral region, where the spurious radioluminescence of fibers is also important. In this work, the radioluminescence response of rare-earth doped Al{sub 2}O{sub 3} samples has been evaluated. The samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium, samarium, cerium and thulium nitrates varying from 0 to 0.15 mo 1%. The influence of the different activators on the Rl spectra has been investigated in order to determine the feasibility of using these compounds for Rl fiberoptic dosimetry. (Author)

Radioluminescence of rare-earth doped aluminum oxide

International Nuclear Information System (INIS)

Santiago, M.; Molina, P.; Barros, V. S.; Khoury, H. J.; Elihimas, D. R.

2011-10-01

Carbon-doped aluminum oxide (Al 2 O 3 :C) is one of the most used radioluminescence (Rl) materials for fiberoptic dosimetry due to its high efficiency and commercial availability. However, this compound presents the drawback of emitting in the spectral region, where the spurious radioluminescence of fibers is also important. In this work, the radioluminescence response of rare-earth doped Al 2 O 3 samples has been evaluated. The samples were prepared by mixing stoichiometric amounts of aluminum nitrate, urea and dopants with different amounts of terbium, samarium, cerium and thulium nitrates varying from 0 to 0.15 mo 1%. The influence of the different activators on the Rl spectra has been investigated in order to determine the feasibility of using these compounds for Rl fiberoptic dosimetry. (Author)

Synthesis and characterization of high-quality water-soluble CdMnTe quantum dots capped by N-acetyl-L-cysteine through hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Gao, Fang; Li, Jiaotian; Wang, Fengxue; Yang, Tanming; Zhao, Dan, E-mail: wqzhdpai@163.com

2015-03-15

High-quality water-soluble Mn{sup 2+} doped CdTe quantum dots (QDs) with N-acetyl-L-cysteine (NAC) as capping reagent have been synthesized through hydrothermal route, allowing a rapid preparation time (<1 h), tunable emitting peaks (from 530 to 646 nm) and excellent quantum yields (approximately 50%). The influences of various experimental variables, including Mn-to-Cd ratio, Te-to-Cd ratio, pH value, and reaction time on the growth rate and luminescent properties of the obtained QDs have been systematically investigated. And the optimum reaction conditions (Cd:Mn:NAC:Te=1.0:1.0:2.4:0.2, pH=9.5, 35 min, 200 °C) are found out. The optical features and structure of the obtained CdMnTe QDs have been characterized through fluorescence spectroscopy, UV absorption spectroscopy and TEM. In particular, we realized qualitative, semi-quantitative and quantitative studies on the doping of Mn to CdTe QDs through XPS, EDS, and AAS. The actual molar ratio of Mn to Cd in CdMnTe QDs (551 nm) is 1.166:1.00, very close to the feed ratios (1:1). - Highlights: • Mn doped CdTe QDs have been synthesized through one-pot hydrothermal route. • The prepared QDs possess excellent quantum yields as high as 63.1% and tunable emitting peaks from 530 to 646 nm. • We found out that the enhancement of Mn:Cd will decrease the QY of the prepared QDs and lead to the blueshift of emission peaks. • The QDs have been characterized through TEM, EDS, XPS, and AAS.

N-doping effectively enhances the adsorption capacity of biochar for heavy metal ions from aqueous solution.

Science.gov (United States)

Yu, Wenchao; Lian, Fei; Cui, Guannan; Liu, Zhongqi

2018-02-01

N-doping was successfully employed to improve the adsorption capacity of biochar (BC) for Cu 2+ and Cd 2+ by direct annealing of crop straws in NH 3 . The surface N content of BC increased more than 20 times by N-doping; meanwhile the content of oxidized-N was gradually diminished but graphitic-N was formed and increased with increasing annealing temperature and duration time. After N-doping, a high graphitic-N percentage (46.4%) and S BET (418.7 m 2 /g) can be achieved for BC. As a result, the N-doped BC exhibited an excellent adsorption capacity for Cu 2+ (1.63 mmol g -1 ) and Cd 2+ (1.76 mmol g -1 ), which was up to 4.0 times higher than that of the original BC. Furthermore, the adsorption performance of the N-doped BC remained stable even at acidic conditions. A positive correlation can be found between adsorption capacity with the graphitic N content on BC surface. The surface chemistry of N-doped BC before and after the heavy metal ions adsorption was carefully examined by XPS and FTIR techniques, which indicated that the adsorption mechanisms mainly included cation-π bonding and complexation with graphitic-N and hydroxyl groups of carbon surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

International Nuclear Information System (INIS)

Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit

2017-01-01

A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm"2 is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

Energy Technology Data Exchange (ETDEWEB)

Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit [Sardar Vallabhbhai National Institute of Technology, Chemical Engineering Department, Surat, Gujarat (India)

2017-08-15

A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm{sup 2} is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

Identification of Ag and Cd photoluminescence in $^{111}$Ag-doped GaN

CERN Document Server

Stötzler, A; Deicher, M

1999-01-01

In order to unambiguously identify the chemical nature of Cd and Ag related optical transitions in GaN, epitaxial GaN layers were implanted with the radioactive isotope $^{111}$Ag which decays into stable $^{111}$Cd. This chemical transmutation was monitored by photoluminescence (PL) spectroscopy. Being an element specific property, the half-life of this decay was used to establish the chemical assignment of the optical transitions to a specific defect. We found that the Ag related transitions consist of a series of four single lines (1.610, 1.600, 1.594, and 1.573 eV), each accompanied by two phonon replicas separated by 63 meV. Cd produces two PL bands centered at 2.7 and 3.2 eV. Additional Cd-related single transitions at 3.341, 3.328, and 3.249 eV have been observed. Exponential fits to the PL intensities yield half-lives of $t_{1/2}^{Ag}$= (7.61$\\pm$0.27) d and $t_{1/2}^{Cd}$=(7.60$\\pm$0.27) d, respectively, in good agreement with the half-life of $^{111}$Ag of 7.45 d. (13 refs).

Thermodynamic analysis of Mg-doped p-type GaN semiconductor

International Nuclear Information System (INIS)

Li Jingbo; Liang Jingkui; Rao Guanghui; Zhang Yi; Liu Guangyao; Chen Jingran; Liu Quanlin; Zhang Weijing

2006-01-01

A thermodynamic modeling of Mg-doped p-type GaN was carried out to describe the thermodynamic behaviors of native defects, dopants (Mg and H) and carriers in GaN. The formation energies of charged component compounds in a four-sublattice model were defined as functions of the Fermi-level based on the results of the first-principles calculations and adjusted to fit experimental data. The effect of the solubility of Mg on the low doping efficiency of Mg in GaN and the role of H in the Mg-doping MOCVD process were discussed. The modeling provides a thermodynamic approach to understand the doping process of GaN semiconductors

Linear and mass attenuation coefficient for CdTe compound of X-rays from 10 to 100 keV energy range in different phases

Energy Technology Data Exchange (ETDEWEB)

Saim, A., E-mail: saim1989asma@gmail.com; Tebboune, A.; Berkok, H.; Belameiri, N.; Belbachir, A.H.

2014-07-25

The Full Potential Linear Muffin Tin Orbitals method within the density functional theory has been utilized to calculate structural and electronic properties of the CdTe compound. We have checked that the CdTe has two phase-transitions from zinc-blend to cinnabar and from cinnabar to rocksalt. We have found that the rigidity, the energy and the nature of the gap change according to the phase change, so we can predict that a CdTe detector may have different behaviors in different phase conditions. In order to investigate this behavior change, the linear and the mass attenuation coefficients of X-ray in rocksalt, zinc-blend and cinnabar structures are calculated from 10 keV to100 keV, using the XCOM data. We have found that when CdTe undergoes a phase transition from zinc-blend to cinnabar, its linear attenuation coefficient decreases down to a value of about 100 times smaller than its initial one, and when it undergoes a transition from cinnabar to rocksalt it increases up to a value about 90 times larger than its initial one.

Design of high quality doped CeO2 solid electrolytes with nanohetero structure

International Nuclear Information System (INIS)

Mori, T.; Ou, D.R.; Ye, F.; Drennan, J.

2006-01-01

Doped cerium (CeO 2 ) compounds are fluorite related oxides which show oxide ionic conductivity higher than yttria-stabilized zirconia in oxidizing atmosphere. As a consequence of this, a considerable interest has been shown in application of these materials for low (400-650 o C) temperature operation of solid oxide fuel cells (SOFCs). In this paper, our experimental data about the influence of microstructure at the atomic level on electrochemical properties were reviewed in order to develop high quality doped CeO 2 electrolytes in fuel cell applications. Using this data in the present paper, our original idea for a design of nanodomain structure in doped CeO 2 electrolytes was suggested. The nanosized powders and dense sintered bodies of M doped CeO 2 (M:Sm,Gd,La,Y,Yb, and Dy) compounds were fabricated. Also nanostructural features in these specimens were introduced for conclusion of relationship between electrolytic properties and domain structure in doped CeO 2 . It is essential that the electrolytic properties in doped CeO 2 solid electrolytes reflect in changes of microstructure even down to the atomic scale. Accordingly, a combined approach of nanostructure fabrication, electrical measurement and structure characterization was required to develop superior quality doped CeO 2 electrolytes in the fuel cells. (author)

Qualitative and Semiquantitative Analysis of Doping Products Seized at the Swiss Border.

Science.gov (United States)

Weber, Christina; Krug, Oliver; Kamber, Matthias; Thevis, Mario

2017-05-12

Substances developed for therapeutic use are also known to be misused by athletes as doping agents and, outside of regulated sport, for image-enhancement. This has generated a market for counterfeit doping substances. Counterfeit doping agents may be of poor pharmaceutical quality and therefore constitute health risks to consumers. This study aims to investigate the pharmaceutical quality of 1,190 doping products seized at the Swiss border. Swiss customs authorities seize incoming shipments potentially containing doping agents. Qualitative and semiquantitative analyses were performed in order to test for prohibited doping substances. The main analytical methods utilized for characterizing confiscated compounds were liquid chromatography-high resolution mass spectrometry, polyacrylamide gel electrophoresis with subsequent in-gel tryptic digestion and identification of peptidic compounds using nanoliquid chromatography-tandem mass spectrometry, and electrochemiluminescence immuno assay. For 889 (75%) of the analyzed products, the label suggested the content of anabolic agents, for 146 samples (12%) peptide hormones or growth factors, and for 113 items (9%) antiestrogens, aromatase inhibitors or other metabolic modulators. For the majority of the investigated products, the pharmaceutical quality was an unsatisfactory standard: nonapproved substances were detected and less than 20% of the products contained the claimed substance in the respective amount. A comprehensive sample of confiscated doping products was analyzed, allowing for monitoring of developments regarding the use of doping substances in Switzerland and for anticipating future trends and challenges in sports drug testing. An alarming number of tested products was of substandard pharmaceutical quality.

Photovoltaic efficiency of intermediate band solar cells based on CdTe/CdMnTe coupled quantum dots

Science.gov (United States)

Prado, Silvio J.; Marques, Gilmar E.; Alcalde, Augusto M.

2017-11-01

In this work we show the calculation of optimized efficiencies of intermediate band solar cells (IBSCs) based on Mn-doped II-VI CdTe/CdMnTe coupled quantum dot (QD) structures. We focus our attention on the combined effects of geometrical and Mn-doping parameters on optical properties and solar cell efficiency. In the framework of {k \\cdot p} theory, we accomplish detailed calculations of electronic structure, transition energies, optical selection rules and their corresponding intra- and interband oscillator strengths. With these results and by following the intermediate band model, we have developed a strategy which allows us to find optimal photovoltaic efficiency values. We also show that the effects of band admixture which can lead to degradation of optical transitions and reduction of efficiency can be partly minimized by a careful selection of the structural parameters and Mn-concentration. Thus, the improvement of band engineering is mandatory for any practical implementation of QD systems as IBSC hardware. Finally, our calculations show that it is possible to reach significant efficiency, up to  ∼26%, by selecting a restricted space of parameters such as quantum dot size and shape and Mn-concentration effects, to improve the modulation of optical absorption in the structures.

Photovoltaic efficiency of intermediate band solar cells based on CdTe/CdMnTe coupled quantum dots.

Science.gov (United States)

Prado, Silvio J; Marques, Gilmar E; Alcalde, Augusto M

2017-11-08

In this work we show the calculation of optimized efficiencies of intermediate band solar cells (IBSCs) based on Mn-doped II-VI CdTe/CdMnTe coupled quantum dot (QD) structures. We focus our attention on the combined effects of geometrical and Mn-doping parameters on optical properties and solar cell efficiency. In the framework of [Formula: see text] theory, we accomplish detailed calculations of electronic structure, transition energies, optical selection rules and their corresponding intra- and interband oscillator strengths. With these results and by following the intermediate band model, we have developed a strategy which allows us to find optimal photovoltaic efficiency values. We also show that the effects of band admixture which can lead to degradation of optical transitions and reduction of efficiency can be partly minimized by a careful selection of the structural parameters and Mn-concentration. Thus, the improvement of band engineering is mandatory for any practical implementation of QD systems as IBSC hardware. Finally, our calculations show that it is possible to reach significant efficiency, up to  ∼26%, by selecting a restricted space of parameters such as quantum dot size and shape and Mn-concentration effects, to improve the modulation of optical absorption in the structures.

New NbCd2 Phase in Niobium-Cadmium Coating Films

Science.gov (United States)

Volodin, V. N.; Tuleushev, Yu. Zh.; Zhakanbaev, E. A.; Tsai, K. V.; Rofman, O. V.

2018-02-01

Solid solutions in the form of alloy coatings have been obtained for the first time in the Cd concentration range of 64.5% using ion-plasma sputtering and the codeposition of Nb and Cd ultrafine particles. This supports thermal fluctuation melting and the coalescence of fine particles. A coating of niobium and cadmium layers less than 2 nm thick at 68 at % Cd results in the formation of a new phase identified as NbCd2. The tetragonal fcc phase with lattice parameters a = 0.84357 nm and c = 0.54514 nm forms directly during film coating. XRD data for the identification of the intermetallic compound have been determined. The thermal stability of the NbCd 2 intermetallic compound is limited by 200°C. The properties of the synthesized NbCd 2 phase are typical of semiconductors.

Nano-architecture based photoelectrochemical water oxidation efficiency enhancement by CdS photoanodes

Science.gov (United States)

Pareek, Alka; Kim, Hyun Gyu; Paik, Pradip; Joardar, Joydip; Borse, Pramod H.

2017-02-01

In the present work, 2D nanostructuring has been utilized to impart an efficiency improvement to the hexagonal phase CdS films for the photoelectrochemical (PEC) cells those were deposited by spray pyrolysis technique. By controlling the aerosol droplet- size, population and impingement time during the spray pyrolysis deposition, various nano-features viz. randomly aligned nanorods, nanotubes and nanowires of CdS has been demonstrated for the first time. A growth mechanism has been proposed to predict the temporal evolution of the nanostructures. The prominent nanoscale structures show improved optical properties in the visible range of solar spectrum. The structural studies validate the morphological differences of nanostructures in terms of the texture coefficient analysis as well as 2D micro x-ray diffraction imaging. Electrochemical characterization is carried out to understand the effect of nanostructuring on the PEC performance of the CdS photoanodes in the sulphide (0.1 M Na2S  +  0.02 M Na2SO3) electrolyte at applied bias of 0.2 V (versus SCE). The evolution of morphology from randomly aligned rods to nanowire is responsible for improved photocurrent (3.5 times). CdS film morphology can be tuned to nanotubes, nano- rose buds and nanorod bunches even by doping Zn2+ ions in CdS lattice. Nano-structuring of doped CdS has shown enhanced performance of the photoanodes. The nanotubes structures yielded highest photocurrent density of 1.6 mA cm-2. Whereas modifying the 2D-nanostructured CdS film by simple MoO3 spray coating yields the photocurrent enhancement to 2.1 mA cm-2.

Target swapping in PLD: An efficient approach for CdS/SiO2 and CdS:Ag(1%)/SiO2 nanocomposite thin films with enhanced luminescent properties

International Nuclear Information System (INIS)

Saxena, Nupur; Kumar, Pragati; Gupta, Vinay

2017-01-01

A novel synthesis method for luminescent and by-products (like CdO) free CdS/SiO 2 and CdS:Ag(1%)/SiO 2 (i.e. 1%Ag doped CdS/SiO 2 ) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS, CdS:Ag(1%) and SiO 2 are used to deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposite thin films by swapping them at a frequency ratio of 2:8 laser pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO 2 in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (i.e. 2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS/ CdS:Ag(1%) nanocrystals in nanocomposite systems after annealing at 500 °C. Highly intense and broad red emission is achieved from CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposites. The efficiencies of emission from pristine CdS:SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposites are found to be enhanced by approximately two times as compared to sole nanocrystalline CdS and CdS:Ag(1%) thin films respectively and further enhanced upto 7 times on annealing the nanocomposite systems at 500 °C. - Graphical abstract: A modified synthesis method for luminescent and by-products (like CdO) free undoped &1% Ag doped CdS/SiO 2 (deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 ) nanocomposite thin films at room temperature by pulsed laser deposition is reported. Targets of CdS or CdS:Ag(1%) and SiO 2 are used to deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposite thin films by swapping them at a frequency of 2:8 pulses/sec. X-ray photoelectron spectroscopy analysis ensures the ratio of CdS to SiO 2 in nanocomposite as 21:79 which is nearly same as the ratio of incident pulses/sec (2:8) on the two targets. Transmission electron micrographs visualize the formation of CdS nanocrystals in nanocomposite systems after annealing at 500 °C. Intense and broad red emission is achieved from deposit CdS/SiO 2 and CdS:Ag(1%)/SiO 2 nanocomposites. The efficiency of

A high stability wavelength-tunable narrow-linewidth and single-polarization erbium-doped fiber laser using a compound-cavity structure

International Nuclear Information System (INIS)

Feng, Ting; Yan, Fengping; Peng, Wanjing; Liu, Shuo; Tan, Siyu; Liang, Xiao; Wen, Xiaodong

2014-01-01

A high stability wavelength-tunable narrow-linewidth and single-polarization erbium-doped fiber laser using a compound-cavity structure is proposed and demonstrated experimentally. The compound-cavity is composed of a main-linear-cavity and a subring-cavity. Using a pump power of 150 mW, the optical signal to noise ratio of the laser output is as high as ∼67 dB; the wavelength and output power fluctuation are 0.7 pm and 0.07 dBm respectively in an experimental period of 1 h; the linewidth of the laser output is as narrow as 650 Hz; the degree of polarization of the laser output is stable at a value of 100.8% in 15 min and the polarization extinction ratio is as high as 30.57 dB; the wavelength-tunable range is as wide as ∼8.1 nm. The proposed fiber laser can be used in areas where high stability, narrow-linewidth, single-polarization and wide wavelength-tunable range are needed. (letter)

Room-temperature polar order in [NH4][Cd(HCOO)3]--a hybrid inorganic-organic compound with a unique perovskite architecture.

Science.gov (United States)

Gómez-Aguirre, L C; Pato-Doldán, B; Stroppa, A; Yáñez-Vilar, S; Bayarjargal, L; Winkler, B; Castro-García, S; Mira, J; Sánchez-Andújar, M; Señarís-Rodríguez, M A

2015-03-02

We report on the hybrid inorganic-organic ammonium compound [NH4][Cd(HCOO)3], which displays a most unusual framework structure: instead of the expected 4(9)·6(6) topology, it shows an ABX3 perovskite architecture with the peculiarity and uniqueness (among all the up-to-date reported hybrid metal formates) that the Cd ions are connected only by syn-anti formate bridges, instead of anti-anti ones. This change of the coordination mode of the formate ligand is thus another variable that can provide new possibilities for tuning the properties of these versatile functional metal-organic framework materials. The room-temperature crystal structure of [NH4][Cd(HCOO)3] is noncentrosymmetric (S.G.: Pna21) and displays a polar axis. DFT calculations and symmetry mode analysis show that the rather large polarization arising from the off-center shift of the ammonium cations in the cavities (4.33 μC/cm(2)) is partially canceled by the antiparallel polarization coming from the [Cd(HCOO)3](-) framework, thus resulting in a net polarization of 1.35 μC/cm(2). As shown by second harmonic generation studies, this net polarization can be greatly increased by applying pressure (Pmax = 14 GPa), an external stimulus that, in turn, induces the appearance of new structural phases, as confirmed by Raman spectroscopy.

Prediction of two-dimensional diluted magnetic semiconductors: Doped monolayer MoS2 systems

KAUST Repository

Cheng, Yingchun

2013-03-05

Using first-principles calculations, we propose a two-dimensional diluted magnetic semiconductor: monolayer MoS2 doped by transition metals. Doping of transition metal atoms from the IIIB to VIB groups results in nonmagnetic states, since the number of valence electrons is smaller or equal to that of Mo. Doping of atoms from the VIIB to IIB groups becomes energetically less and less favorable. Magnetism is observed for Mn, Fe, Co, Zn, Cd, and Hg doping, while for the other dopants from these groups it is suppressed by Jahn-Teller distortions. Analysis of the binding energies and magnetic properties indicates that (Mo,X)S2 (X=Mn, Fe, Co, and Zn) are promising systems to explore two-dimensional diluted magnetic semiconductors.

Theoretical investigation of the electronic and magnetic properties of TM (TM=Ti, V, and Cr)-doped w-BN compound

Energy Technology Data Exchange (ETDEWEB)

Jiménez, Gladys Casiano; López, César Ortega [Grupo Avanzado de Materiales y Sistemas Complejos GAMASCO, Universidad de Córdoba, Montería (Colombia); Espitia R, Miguel J., E-mail: mespitiar@udistrital.edu.co [Grupo GEFEM, Universidad Distrital Francisco José de Caldas, Bogotá (Colombia)

2016-03-15

The electronic and magnetic properties of w-BN compound doped with Ti, V, and Cr atoms are calculated by means of the pseudopotential method, employed exactly as implemented in computational Quantum ESPRESSO code. For the description of the electron-electron interaction, generalized gradient approximation (GGA) was used. A half-metallic behavior is predicted for the concentrations B{sub 0.9375}Ti{sub 0.0625}N, B{sub 0.9375}V{sub 0.0625}N, and B{sub 0.9375}Cr{sub 0.0625}N, because of the fact that the majority spins are metallic and the minority spins are semiconducting. We found magnetic moments of 1.0, 2.0 and 3.0 µ{sub β} per supercell, respectively. The main contribution to the magnetic moment mainly comes from the transition metals Ti, V, and Cr, with partialmoments of 0.88 µ{sub β}, 1.75 µ{sub β}, and 2.65 µ{sub β}, respectively. These compounds are good candidates for potential applications in spintronic and as spin injectors. - Highlights: • The B{sub 0.9375}Ti{sub 0.0625}N, B{sub 0.9375}V{sub 0.0625}N, and B{sub 0.9375}Cr{sub 0.0625}N compounds has a magnetic properties. • The magnetic moment for compounds are 1.0, 2.0 and 3.0 µ{sub β} per supercell, respectively. • The magnetic moment mainly comes from the transition metals Ti, V, and Cr, with local moments of 0.88 µ{sub β}, 1.75 µ{sub β}, and 2.65 µ{sub β}, respectively. • The compounds have a half-metallic behavior.

Coordination Architectures of energetic Cd (II) coordination polymers constructed by the bifunctional substituted-tetrazole-carboxylate ligands

Energy Technology Data Exchange (ETDEWEB)

Shen, Lei; Bai, Yu; Min, Yu-Ting; Jia, Tian-Tian; Wu, Qi; Wang, Jing; Geng, Fei; Cheng, Hong-Jian [Department of Chemistry & Materials Engineering, Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu 215500 (China); Zhu, Dun-Ru [College of Chemical Engineering, State Key Laboratory of Materials-oriented Chemical Engineering, Nanjing Tech University, Nanjing 210009 (China); Yang, Jie, E-mail: jieyang@cslg.edu.cn [Department of Chemistry & Materials Engineering, Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu 215500 (China); Yang, Gao-Wen, E-mail: ygwsx@126.com [Department of Chemistry & Materials Engineering, Jiangsu Key Laboratory of Advanced Functional Materials, Changshu Institute of Technology, Changshu 215500 (China)

2016-12-15

Three different tetrazole-carboxylate ligands, monotetrazole-carboxylate H{sub 2}tza (H{sub 2}tza=1,5-tetrazole-diacetic acid), Hpztza (Hpztza=5-(2-pyrazinyl)tetrazole-2(1-methyl)acetic acid), ditetrazole-carboxylate H{sub 2}tzpha (H{sub 2}tzpha=1,3-di(tetrazole-5-yl)benzene-N2,N2′-diacetic acid) have been chosen to react with CdCl{sub 2}·6H{sub 2}O, resulting in the formation of three new compounds [Cd{sub 2}(tza){sub 2}] (1), [Cd(pztza){sub 2}] (2) and [Cd(tzpha)(CH{sub 3}OH){sub 2}] (3). The coordinate sites of the three ligands are major influenced by the different substituted group of tetrazole ring. These compounds have been characterized by elemental analysis, IR and single crystal X-ray diffraction. Compound 1 displays a complex 3D structure; compound 2 shows a 3D network and compound 3 features a 2D layer network. Furthermore, the luminescence properties investigated at room temperature in the solid state showed excellent ligand-centered luminescence. The obvious enhancement in luminescence makes these compounds potential materials for optical use. The differential scanning calorimetry (DSC) and thermogravimetric-differential thermogravimetric (TG-DTG) analyses were applied to evaluate the thermal decomposition behavior of such compounds, showing that compounds 2 and 3 can be used as potential energetic materials. The relevant thermodynamic parameters ΔH, ΔS and ΔG were calculated as well. - Graphical abstract: H{sub 2}tza, Hpztza and H{sub 2}tzpha have been prepared. Three novel Cd (II)compounds were synthesized by reactions of CdCl{sub 2}·6H{sub 2}O, namely three dimensional [Cd{sub 2}(tza){sub 2}] (1), three dimensional [Cd(pztza){sub 2}] (2), and two dimensional [Cd(tzpha)(CH{sub 3}O){sub 2}] (3). The luminescences were investigated. Furthermore, the DSC show compounds 1 and 3 can be used as potential explosive materials.

RF sputtered HgCdTe films for tandem cell applications

International Nuclear Information System (INIS)

Wang, S.L.; Lee, S.H.; Gupta, A.; Compaan, A.D.

2004-01-01

Polycrystalline Hg 1-x Cd x Te films were investigated for their potential as bottom cells of a CdTe-based tandem solar cell. The films were deposited by RF sputtering from a cold pressed target containing 30% HgTe+70% CdTe. The as-deposited films were highly resistive with (111) preferred orientation and a bandgap of ∝1.0 eV. Various thermal treatment schemes were investigated under different conditions of ambient and temperature to reduce the resistivity. The film properties were analyzed using infrared transmission spectra, energy dispersive X-ray spectra and X-ray diffraction. N doped p-HgCdTe films were also prepared by reactive sputtering in a N 2 /Ar ambient. P-n junction solar cells were fabricated with CdS films as the heterojunction partner. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Density functional theory calculations establish the experimental evidence of the DX center atomic structure in CdTe.

Science.gov (United States)

Lany, Stephan; Wolf, Herbert; Wichert, Thomas

2004-06-04

The In DX center and the DX-like configuration of the Cd host atom in CdTe are investigated using density functional theory. The simultaneous calculation of the atomic structure and the electric field gradient (EFG) allows one to correlate the theoretically predicted structure of the DX center with an experimental observable, namely, the EFG obtained from radioactive 111In/111Cd probe atoms in In doped CdTe. In this way, the experimental identification of the DX center structure is established.

Preparation of manganese doped cadmium sulfide nanoparticles in zincblende phase and their magnetic properties.

Science.gov (United States)

Nakaya, Masafumi; Tanaka, Itaru; Muramatsu, Atsushi

2012-12-01

In this study, the random dope of Mn into CdS nanoparticles in zincblende phase has been carried out under the mild reaction condition. The resulting nanoparticles were characterized by energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), X-ray diffractometer (XRD), UV-Vis spectrometer, PL spectrometer, and SQUID. EDX showed that the compositions of Mn doped CdS nanoparticles were readily controlled. TEM showed the particle sizes were not significantly affected by the compositions, retaining to be ca. 3 nm with a narrow size distribution. UV-Vis and PL spectra of the resulting nanoparticles showed the intra-Mn level may be affected by the quantum size effect. SQUID measurement showed that the resulting nanoparticles showed diamagnetism, paramagnetism and superparamagnetism dependent on Mn content.

Voc enhancement of a solar cell with doped Li+-PbS as the active layer

Science.gov (United States)

Chávez Portillo, M.; Alvarado Pulido, J.; Gallardo Hernández, S.; Soto Cruz, B. S.; Alcántara Iniesta, S.; Gutiérrez Pérez, R.; Portillo Moreno, O.

2018-06-01

In this report, we investigate the fabrication of solar cells obtained by chemical bath technique, based on CdS as window layer and PbS and PbS-Li+-doped as the active layer. We report open-circuit-voltage Voc values of ∼392 meV for PbS and ∼630 meV for PbSLi+-doped, a remarkable enhanced in the open circuit voltage is shown for solar cells with doped active layer. Li+ ion passivate the dangling bonds in PbS-metal layer interface in consequence reducing the recombination centers.

Thermopower studies of doped CeAl sub 2 and UAl sub 2

CERN Document Server

Park, J G

1997-01-01

We have studied the thermopower of U doped CeAl sub 2 and Ce and La doped UAl sub 2. Despite different ground state properties of CeAl sub 2 and UAl sub 2 , the former being an antiferromagnetic heavy-fermion compound and the latter non-magnetic, we have found that not only thermopower data for pure CeAl sub 2 and UAl sub 2 are similar but also the thermopower results of doped samples behave similarly. Although the similarity seen in pure systems is yet to be understood, we interpret the doping effects as the results of changes in energy dependent relaxation time with doping. (author)

Large enhancement in photocurrent by Mn doping in CdSe/ZTO quantum dot sensitized solar cells.

Science.gov (United States)

Pimachev, Artem; Poudyal, Uma; Proshchenko, Vitaly; Wang, Wenyong; Dahnovsky, Yuri

2016-09-29

We find a large enhancement in the efficiency of CdSe quantum dot sensitized solar cells by doping with manganese. In the presence of Mn impurities in relatively small concentrations (2.3%) the photoelectric current increases by up to 190%. The average photocurrent enhancement is about 160%. This effect cannot be explained by a light absorption mechanism because the experimental and theoretical absorption spectra demonstrate that there is no change in the absorption coefficient in the presence of the Mn impurities. To explain such a large increase in the injection current we propose a tunneling mechanism of electron injection from the quantum dot LUMO state to the Zn 2 SnO 4 (ZTO) semiconductor photoanode. The calculated enhancement is approximately equal to 150% which is very close to the experimental average value of 160%. The relative discrepancy between the calculated and experimentally measured ratios of the IPCE currents is only 6.25%. For other mechanisms (such as electron trapping, etc.) the remaining 6.25% cannot explain the large change in the experimental IPCE. Thus we have indirectly proved that electron tunneling is the major mechanism of photocurrent enhancement. This work proposes a new approach for a significant improvement in the efficiency of quantum dot sensitized solar cells.

TiO2 nanocrystals decorated Z-schemed core-shell CdS-CdO nanorod arrays as high efficiency anodes for photoelectrochemical hydrogen generation.

Science.gov (United States)

Li, Chia-Hsun; Hsu, Chan-Wei; Lu, Shih-Yuan

2018-07-01

TiO 2 nanocrystals decorated core-shell CdS-CdO nanorod arrays, TiO 2 @CdO/CdS NR, were fabricated as high efficiency anodes for photoelctrochemical hydrogen generation. The novel sandwich heterostructure was constructed from first growth of CdS nanorod arrays on a fluorine doped tin oxide (FTO) substrate with a hydrothermal process, followed by in situ generation of CdO thin films of single digit nanometers from the CdS nanorod surfaces through thermal oxidation, and final decoration of TiO 2 nanocrystals of 10-20 nm via a successive ionic layer absorption and reaction process. The core-shell CdS-CdO heterostructure possesses a Z-scheme band structure to enhance interfacial charge transfer, facilitating effective charge separation to suppress electron-hole recombination within CdS for much improved current density generation. The final decoration of TiO 2 nanocrystals passivates surface defects and trap states of CdO, further suppressing surface charge recombination for even higher photovoltaic conversion efficiencies. The photoelectrochemical performances of the plain CdS nanorod array were significantly improved with the formation of the sandwich heterostructure, achieving a photo current density of 3.2 mA/cm 2 at 1.23 V (vs. RHE), a 141% improvement over the plain CdS nanorod array and a 32% improvement over the CdO/CdS nanorod array. Copyright © 2018 Elsevier Inc. All rights reserved.

Small molecule inhibition of hepatitis C virus E2 binding to CD81

International Nuclear Information System (INIS)

Van Compernolle, Scott E.; Wiznycia, Alexander V.; Rush, Jeremy R.; Dhanasekaran, Muthu; Baures, Paul W.; Todd, Scott C.

2003-01-01

The hepatitis C virus (HCV) is a causal agent of chronic liver infection, cirrhosis, and hepatocellular carcinoma infecting more than 170 million people. CD81 is a receptor for HCV envelope glycoprotein E2. Although the binding of HCV-E2 with CD81 is well documented the role of this interaction in the viral life cycle remains unclear. Host specificity and mutagenesis studies suggest that the helix D region of CD81 mediates binding to HCV-E2. Structural analysis of CD81 has enabled the synthesis of small molecules designed to mimic the space and hydrophobic features of the solvent-exposed face on helix D. Utilizing a novel bis-imidazole scaffold a series of over 100 compounds has been synthesized. Seven related, imidazole-based compounds were identified that inhibit binding of HCV-E2 to CD81. The inhibitory compounds have no short-term effect on cellular expression of CD81 or other tetraspanins, do not disrupt CD81 associations with other cell surface proteins, and bind reversibly to HCV-E2. These results provide an important proof of concept that CD81-based mimics can disrupt binding of HCV-E2 to CD81

[Mechanism Study of the Smectite-OR-SH Compound for Reducing Cadmium Uptake by Plants in Contaminated Soils].

Science.gov (United States)

Zeng, Yan-jun; Zhou, Zhi-jun; Zhao, Qiu-xiang

2015-06-01

Adsorption and desorption experiments, pot experiments and characterization test were performed to investigate the immobilization effect and mechanism of the smectite-OR-SH compound for reducing cadmium uptake by plants in contaminated soils. The results showed that the saturated adsorption capacity for the adsorption of Cd2+ on smectite raised distinctly after functionalized. The adsorption of Cd2+ on smectite-OR-SH compound was very stable and it was difficult for Cd2+ to be desorbed from it. Crop yields promoted differently in original soil, Cd 3 mg x kg(-1) soil and Cd 10 mg x kg(-1) soil after adding the smectite-OR-SH compound. And the cadmium content of the cabbage reduced 61.00%, 62.10% and 83.73% respectively compare with the control. Characterization test analysis showed that Cd was adsorbed by the compound successfully and ligand interaction occurred between Cd and the thiol group. Floc amount on the compound surface increased correspondingly. In addition to electrostatic adsorption, ion exchange and hydroxyl ligand adsorption, the reaction mechanism of smectite-OR-SH compound with Cd was mainly sulfhydryl ligand adsorption.

Heavy doping of CdTe single crystals by Cr ion implantation

Science.gov (United States)

Popovych, Volodymyr D.; Böttger, Roman; Heller, Rene; Zhou, Shengqiang; Bester, Mariusz; Cieniek, Bogumil; Mroczka, Robert; Lopucki, Rafal; Sagan, Piotr; Kuzma, Marian

2018-03-01

Implantation of bulk CdTe single crystals with high fluences of 500 keV Cr+ ions was performed to achieve Cr concentration above the equilibrium solubility limit of this element in CdTe lattice. The structure and composition of the implanted samples were studied using secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) to characterize the incorporation of chromium into the host lattice and to investigate irradiation-induced damage build-up. It was found that out-diffusion of Cr atoms and sputtering of the targets alter the depth distribution and limit concentration of the projectile ions in the as-implanted samples. Appearance of crystallographically oriented, metallic α-Cr nanoparticles inside CdTe matrix was found after implantation, as well as a strong disorder at the depth far beyond the projected range of the implanted ions.

Electronic and magnetic properties of SnS2 monolayer doped with 4d transition metals

Science.gov (United States)

Xiao, Wen-Zhi; Xiao, Gang; Rong, Qing-Yan; Chen, Qiao; Wang, Ling-Ling

2017-09-01

We investigate the electronic structures and magnetic properties of SnS2 monolayers substitutionally doped with 4-d transition-metal through systematic first principles calculations. The doped complexes exhibit interesting electronic and magnetic behaviors, depending on the interplay between crystal field splitting, Hund's rule, and 4d levels. The system doped with Y is nonmagnetic metal. Both the Zr- and Pd-doped systems remain nonmagnetic semiconductors. Doping results in half-metallic states for Nb-, Ru-, Rh-, Ag, and Cd doped cases, and magnetic semiconductors for systems with Mo and Tc dopants. In particular, the Nb- and Mo-doped systems display long-ranged ferromagnetic ordering with Curie temperature above room temperature, which are primarily attributable to the double-exchange mechanism, and the p-d/p-p hybridizations, respectively. Moreover, The Mo-doped system has excellent energetic stability and flexible mechanical stability, and also possesses remarkable dynamic and thermal (500 K) stability. Our studies demonstrate that Nb- and Mo-doped SnS2 monolayers are promising candidates for preparing 2D diluted magnetic semiconductors, and hence will be a helpful clue for experimentalists.

Al2O3 doped TiO2 ceramic waste forms

International Nuclear Information System (INIS)

Uno, Masayoshi; Kinoshita, Hajime; Sakai, Etsuro; Ikeda, Akira; Matsumoto, Y.; Yamanaka, Shinsuke

1999-01-01

Melting of the mixture of Nd 2 O 3 , CeO 2 , SrO, TiO 2 and Al 2 O 3 at 1673 K for 1 hour produced one RE 2 Ti 3 O 9 phase compound. Differential Scanning Calorimetry (DSC) measurement showed that the melting temperature of this compound was 1646 K. Density of the alumina doped oxide was higher than that of the oxide obtained by the pressing and sintering without alumina. Vickers hardness of the oxide obtained by the pressing and sintering was 5.3 GPa and nearly same as that of glass waste. That of the alumina doped oxide was around 7 GPa. 7 days Soxhlet leach test (MCC-5) followed by Inductively Coupled Plasma Spectrometry (ICP) showed that normalized leaching rate of Ti for the oxide obtained by the pressing and sintering was 5.54 x 10 -3 kg/m 2 and that for the alumina doped oxide was 2.24 x 10 -3 kg/m 2 . The value of Sr for the pressed and sintered sample was 0.034 x 10 -3 kg/m 2 but that for alumina doped sample was below the detection limit (0.01 x 10 -3 kg/m 2 ). Al was not detected from the leachate of the alumina doped sample. (author)

Fluorescence-enhanced gadolinium-doped zinc oxide quantum dots for magnetic resonance and fluorescence imaging.

Science.gov (United States)

Liu, Yanlan; Ai, Kelong; Yuan, Qinghai; Lu, Lehui

2011-02-01

We report here the development of Gd-doped ZnO quantum dots (QDs) as dual modal fluorescence and magnetic resonance imaging nanoprobes. They are fabricated in a simple, versatile and environmentally friendly method, not only decreasing the difficulty and complexity, but also avoiding the increase of particle's size brought about by silica coating procedure in the synthesis of nanoprobes reported previously. These nanoprobes, with exceptionally small size and enhanced fluorescence resulting from the Gd doping, can label successfully the HeLa cells in short time and present no evidence of toxicity or adverse affect on cell growth even at the concentration up to 1 mm. These results show that such nanoprobes have low toxicity, especially in comparison with the traditional PEGylated CdSe/ZnS or CdSe/CdS QDs. In MRI studies, they exert strong positive contrast effect with a large longitudinal relaxivity (r(1)) of water proton of 16 mm(-1) s(-1). Their capability of imaging HeLa cells with MRI implies that they have great potential as MRI contrast agents. Combining the high sensitivity of fluorescence imaging with high spatial resolution of MRI, We expect that the as-prepared Gd-doped Zno QDs can provide a better reliability of the collected data and find promising applications in biological, medical and other fields. Copyright © 2010 Elsevier Ltd. All rights reserved.

Structural and optical characterization of oxygenated CdTe/Sm3+ in sol-gel silica glasses

International Nuclear Information System (INIS)

Mathew, Siby; Rejikumar, P.R.; Adiyodi, Amrutha K.; Jyothy, P.V.; Unnikrishnan, N.V.

2008-01-01

Oxygenated cadmium telluride co-doped with rare earth element samarium is prepared by sol-gel method. Sample is air annealed at 200, 500 and 800 deg. C. The absorption and fluorescence spectra are analysed using Judd-Ofelt analysis to obtain J-O parameters. X-ray spectroscopy analysis shows the presence of thermally grown CdTeO 3 phase developed at the expense of CdTe phase on heat treatment for samples annealed at 800 deg. C. The FT-IR spectrum of the sample is taken at different annealing temperatures and the assignments of the absorption bands are compiled which shows the gradual evolution of the rigid glassy network formed. Enhanced fluorescence from air annealed Co-doped samples are also investigated

Effects of Lu and Tm Doping on Thermoelectric Properties of Bi2Te3 Compound

Science.gov (United States)

Yaprintsev, Maxim; Lyubushkin, Roman; Soklakova, Oxana; Ivanov, Oleg

2018-02-01

The Bi2Te3, Bi1.9Lu0.1Te3 and Bi1.9Tm0.1Te3 thermoelectrics of n-type conductivity have been prepared by the microwave-solvothermal method and spark plasma sintering. These compounds behave as degenerate semiconductors from room temperature up to temperature T d ≈ 470 K. Within this temperature range the temperature behavior of the specific electrical resistivity is due to the temperature changes of electron mobility determined by acoustic and optical phonon scattering. Above T d, an onset of intrinsic conductivity takes place when electrons and holes are present. At the Lu and Tm doping, the Seebeck coefficient increases, while the specific electrical resistivity and total thermal conductivity decrease within the temperature 290-630 K range. The increase of the electrical resistivity is related to the increase of electron concentration since the Tm and Lu atoms are donor centres in the Bi2Te3 lattice. The increase of the density-of-state effective mass for conduction band can be responsible for the increase of the Seebeck coefficient. The decrease of the total thermal conductivity in doped Bi2Te3 is attributed to point defects like the antisite defects and Lu or Tm atoms substituting for the Bi sites. In addition, reducing the electron thermal conductivity due to forming a narrow impurity (Lu or Tm) band having high and sharp density-of-states near the Fermi level can effectively decrease the total thermal conductivity. The thermoelectric figure-of-merit is enhanced from ˜ 0.4 for undoped Bi2Te3 up to ˜ 0.7 for Bi1.9Tm0.1Te3 and ˜ 0.9 for Bi1.9Lu0.1Te3.

Reddish-orange, neutral and warm white emissions in Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses

Science.gov (United States)

Rodríguez-Carvajal, David A.; Meza-Rocha, A. N.; Caldiño, U.; Lozada-Morales, R.; Álvarez, E.; Zayas, Ma. E.

2016-11-01

Eu3+, Dy3+ and Dy3+/Eu3+ doped CdO-GeO2-TeO2 glasses were prepared using the melt-quenching process and analyzed by X-diffraction, Raman spectroscopy, excitation and emission spectra, and emission decay time profiles. The lack of X ray diffraction peaks revealed that all samples are amorphous. Vibrational modes associated with Tesbnd Osbnd Te and Gesbnd Osbnd Ge related bonds and molecular oxygen were detected by Raman spectroscopy. The luminescence characteristics were studied upon excitations that correspond with the emission of InGaN (370-420 nm) based LEDs. The Eu3+ singly doped glass displayed reddish-orange global emission, with x = 0.601 and y = 0.349 CIE1931 chromaticity coordinates, upon 393 nm excitation. Neutral emission with x = 0.373 and y = 0.412 CIE1931 chromaticity coordinates and correlated color temperature (CCT) of 4400 K, was achieved in the Dy3+ singly doped glass excited at 388 nm. The Dy3+/Eu3+ co-doped glass exhibited warm, neutral and soft warm white emissions with CCT values of 3435, 4153 and 2740 K, under excitations at 382, 388 and 393 nm, respectively, depending mainly on the Dy3+ and Eu3+ relative excitation. The Dy3+ excitation bands observed in the Dy3+/Eu3+ glass by monitoring the 611 nm Eu3+ emission, suggest that Dy3+ → Eu3+ energy transfer takes place, despite the fact that the Dy3+ emission decays in the Dy3+ and Dy3+/Eu3+ doped glass, remain without changes. The shortening of Eu3+ decay in presence of Dy3+ was attributed to an Eu3+ → Dy3+ non-radiative energy transfer process, which according with the Inokuti-Hirayama model might be dominated through an electric quadrupole-quadrupole interaction, with efficiency and probability of 5.5% and 51.6 s-1, respectively.

High photocurrent gain in NiO thin film/M-doped ZnO nanorods (M=Ag, Cd and Ni) heterojunction based ultraviolet photodiodes

Energy Technology Data Exchange (ETDEWEB)

Echresh, Ahmad, E-mail: ahmadechresh@gmail.com [Department of Science and Technology, Physical Electronics and Nanotechnology Division, Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Echresh, Mohammad [Department of Physics, Sanati Hoveizeh University, Ahvaz (Iran, Islamic Republic of); Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-5818358183 Linköping (Sweden); Nur, Omer; Willander, Magnus [Department of Science and Technology, Physical Electronics and Nanotechnology Division, Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden)

2016-10-15

The thermal evaporation method has been used to deposit p-type NiO thin film, which was combined with hydrothermally grown n-type pure and M-doped ZnO nanorods (M=Ag, Cd and Ni) to fabricate a high performance p-n heterojunction ultraviolet photodiodes. The fabricated photodiodes show high rectification ratio and relatively low leakage current. The p-NiO/n-Zn{sub 0.94}Ag{sub 0.06}O heterojunction photodiode displays the highest photocurrent gain (~1.52×10{sup 4}), a photoresponsivity of ~4.48×10{sup 3} AW{sup −1} and a photosensitivity of ~13.56 compared with the other fabricated photodiodes. The predominated transport mechanisms of the p-n heterojunction ultraviolet photodiodes at low and high applied forward bias may be recombination-tunneling and space charge limited current, respectively.

Intrinsically High Thermoelectric Performance in AgInSe2 n-Type Diamond-Like Compounds.

Science.gov (United States)

Qiu, Pengfei; Qin, Yuting; Zhang, Qihao; Li, Ruoxi; Yang, Jiong; Song, Qingfeng; Tang, Yunshan; Bai, Shengqiang; Shi, Xun; Chen, Lidong

2018-03-01

Diamond-like compounds are a promising class of thermoelectric materials, very suitable for real applications. However, almost all high-performance diamond-like thermoelectric materials are p-type semiconductors. The lack of high-performance n-type diamond-like thermoelectric materials greatly restricts the fabrication of diamond-like material-based modules and their real applications. In this work, it is revealed that n-type AgInSe 2 diamond-like compound has intrinsically high thermoelectric performance with a figure of merit ( zT ) of 1.1 at 900 K, comparable to the best p-type diamond-like thermoelectric materials reported before. Such high zT is mainly due to the ultralow lattice thermal conductivity, which is fundamentally limited by the low-frequency Ag-Se "cluster vibrations," as confirmed by ab initio lattice dynamic calculations. Doping Cd at Ag sites significantly improves the thermoelectric performance in the low and medium temperature ranges. By using such high-performance n-type AgInSe 2 -based compounds, the diamond-like thermoelectric module has been fabricated for the first time. An output power of 0.06 W under a temperature difference of 520 K between the two ends of the module is obtained. This work opens a new window for the applications using the diamond-like thermoelectric materials.

Emitter/absorber interface of CdTe solar cells

Energy Technology Data Exchange (ETDEWEB)

Song, Tao, E-mail: tsong241@gmail.com; Sites, James R. [Physics Department, Colorado State University, Fort Collins, Colorado 80523 (United States); Kanevce, Ana [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

2016-06-21

The performance of CdTe solar cells can be very sensitive to the emitter/absorber interface, especially for high-efficiency cells with high bulk lifetime. Performance losses from acceptor-type interface defects can be significant when interface defect states are located near mid-gap energies. Numerical simulations show that the emitter/absorber band alignment, the emitter doping and thickness, and the defect properties of the interface (i.e., defect density, defect type, and defect energy) can all play significant roles in the interface recombination. In particular, a type I heterojunction with small conduction-band offset (0.1 eV ≤ ΔE{sub C} ≤ 0.3 eV) can help maintain good cell efficiency in spite of high interface defect density, much like with Cu(In,Ga)Se{sub 2} (CIGS) cells. The basic principle is that positive ΔE{sub C}, often referred to as a “spike,” creates an absorber inversion and hence a large hole barrier adjacent to the interface. As a result, the electron-hole recombination is suppressed due to an insufficient hole supply at the interface. A large spike (ΔE{sub C} ≥ 0.4 eV), however, can impede electron transport and lead to a reduction of photocurrent and fill-factor. In contrast to the spike, a “cliff” (ΔE{sub C} < 0 eV) allows high hole concentration in the vicinity of the interface, which will assist interface recombination and result in a reduced open-circuit voltage. Another way to mitigate performance losses due to interface defects is to use a thin and highly doped emitter, which can invert the absorber and form a large hole barrier at the interface. CdS is the most common emitter material used in CdTe solar cells, but the CdS/CdTe interface is in the cliff category and is not favorable from the band-offset perspective. The ΔE{sub C} of other n-type emitter choices, such as (Mg,Zn)O, Cd(S,O), or (Cd,Mg)Te, can be tuned by varying the elemental ratio for an optimal positive value of ΔE{sub C}. These

Studies on AC Electrical Conductivity of CdCl2 Doped PVA Polymer Electrolyte

Directory of Open Access Journals (Sweden)

M. B. Nanda Prakash

2013-01-01