Characterization of silver halide fiber optics and hollow silica waveguides for use in the construction of a mid-infrared attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy probe.

PubMed

Damin, Craig A; Sommer, André J

2013-11-01

Advances in fiber optic materials have allowed for the construction of fibers and waveguides capable of transmitting infrared radiation. An investigation of the transmission characteristics associated with two commonly used types of infrared-transmitting fibers/waveguides for prospective use in a fiber/waveguide-coupled attenuated total internal reflection (ATR) probe was performed. Characterization of silver halide polycrystalline fiber optics and hollow silica waveguides was done on the basis of the transmission of infrared light using a conventional fiber optic coupling accessory and an infrared microscope. Using the fiber optic coupling accessory, the average percent transmission for three silver halide fibers was 18.1 ± 6.1% relative to a benchtop reflection accessory. The average transmission for two hollow waveguides (HWGs) using the coupling accessory was 8.0 ± 0.3%. (Uncertainties in the relative percent transmission represent the standard deviations.) Reduced transmission observed for the HWGs was attributed to the high numerical aperture of the coupling accessory. Characterization of the fibers/waveguides using a zinc selenide lens objective on an infrared microscope indicated 24.1 ± 7.2% of the initial light input into the silver halide fibers was transmitted. Percent transmission obtained for the HWGs was 98.7 ± 0.1%. Increased transmission using the HWGs resulted from the absence or minimization of insertion and scattering losses due to the hollow air core and a better-matched numerical aperture. The effect of bending on the transmission characteristics of the fibers/waveguides was also investigated. Significant deviations in the transmission of infrared light by the solid-core silver halide fibers were observed for various bending angles. Percent transmission greater than 98% was consistently observed for the HWGs at the bending angles. The combined benefits of high percent transmission, reproducible instrument responses, and increased bending tolerance indicated HWGs should be preferred in the construction of a fiber/waveguide-coupled ATR probe.

Silver halide sensitized gelatin derived from BB-640 holographic emulsion.

PubMed

Neipp, C; Pascual, I; Beléndez, A

1999-03-10

Silver halide sensitized gelatin (SHSG) is one of the most interesting techniques for the production of holographic optical elements, achieving relatively high sensitivity of photographic material with a low scattering of dichromated gelatin. Here we present experimental results for SHSG derived from the novel BB-640, a red-sensitive ultra-fine-grain emulsion from Holographic Recording Technologies (Steinau, Germany). The material is characterized before recording and after processing, and information about the thickness, absorption, and refractive-index modulation of the final holograms is obtained. The influence of the developer is analyzed, and diffraction efficiencies as great as 96.2% (after allowing for reflections) with a transmission of 1% and absorption and scatter losses of 2.8% are obtained with AAC developer. Our investigations reveal that high-quality SHSG transmission holograms may be obtained with the new BB-640 plates.

Thick phase holographic gratings recorded on BB-640 and PFG-01 silver halide materials

NASA Astrophysics Data System (ADS)

Neipp, Cristian; Márquez, Andrés; Pascual, Inmaculada; Beléndez, Augusto

2003-09-01

Photographic emulsions are still widely used to record holographic optical elements. In particular, if high diffraction efficiencies are needed, phase volume holograms are preferably recorded on these emulsions. Two particular techniques producing high-quality volume phase holograms are fixation-free rehalogenating bleaching and the use of silver-halide-sensitized gelatin. In this work we compare these two particular techniques applied to three different red-sensitive emulsions: Agfa 8E75 HD, BB-640, and Slavich PFG-01 emulsions. The differences between these emulsions determine the particular experimental conditions needed to record high-quality volume holograms on them. In this work these differences are analysed, and also their influence on the experimental procedure.

Potentiometric titration of thiols, cationic surfactants and halides using a solid-state silver-silver sulphide electrode.

PubMed

Pinzauti, S; Papeschi, G; La Porta, E

1983-01-01

A rugged, low resistance silver-silver sulphide solid-state electrode for determining pharmaceuticals as authentic samples or in dosage forms by potentiometric titration is described. Sodium tetraphenylborate, mercury(II) acetate and silver nitrate (0.01) M were employed as titrants in the analysis of cationic surfactants (cetylpyridinium chloride, benzethonium chloride, benzalkonium chloride and chlorhexidine salts), antithyroid drugs (methimazole and propylthiouracil) or sodium halides respectively.

Well-defined N-heterocyclic carbene silver halides of 1-cyclohexyl-3-arylmethylimidazolylidenes: synthesis, structure and catalysis in A3-reaction of aldehydes, amines and alkynes.

PubMed

Li, Yanbo; Chen, Xiaofeng; Song, Yin; Fang, Ling; Zou, Gang

2011-03-07

Structurally well-defined N-heterocyclic carbene silver chlorides and bromides supported by 1-cyclohexyl-3-benzylimidazolylidene (CyBn-NHC) or 1-cyclohexyl-3-naphthalen-2-ylmethylimidazolylidene (CyNaph-NHC) were synthesized by reaction of the corresponding imidazolium halides with silver(I) oxide while cationic bis(CyBn-NHC) silver nitrate was isolated under similar conditions using imidazolium iodide in the presence of sodium nitrate. Single-crystal X-ray diffraction revealed a dimeric structure through a nonpolar weak-hydrogen-bond supported Ag-Ag bond for 1-cyclohexyl-3-benzylimidazolylidene silver halides [(CyBn-NHC)AgX](2) (X = Cl, 1; Br, 2) but a monomeric structure for N-heterocyclic carbene silver halides with the more sterically demanding 1-cyclohexyl-3-naphthalen-2-ylmethylimidazolylidene ligand (CyNaph-NHC)AgX (X = Cl, 4; Br, 5). Cationic biscarbene silver nitrate [(CyBn-NHC)(2)Ag](+)NO(3)(-)3 assumed a cis orientation with respect to the two carbene ligands. The monomeric complexes (CyNaph-NHC)AgX 4 and 5 showed higher catalytic activity than the dimeric [(CyBn-NHC)AgX](2)1 and 2 as well as the cationic biscarbene silver nitrate 3 in the model three component reaction of 3-phenylpropionaldehyde, phenylacetylene and piperidine with chloride 4 performing best and giving product in almost quantitative yield within 2 h at 100 °C. An explanation for the structure-activity relationship in N-heterocyclic carbene silver halide catalyzed three component reaction is given based on a slightly modified mechanism from the one in literature.

Silver nanoparticles with planar twinned defects: effect of halides for precise tuning of plasmon resonance maxima from 400 to >900 nm.

PubMed

Cathcart, Nicole; Frank, Andrew J; Kitaev, Vladimir

2009-12-14

We studied effects of halides on morphology of planar twinned silver nanoparticles and demonstrated application of these effects to precisely tune silver surface plasmon resonance maxima in a broad vis-NIR range using a reliable two-stage modification protocol.

Chemistry of the Konica Dry Color System

NASA Astrophysics Data System (ADS)

Suda, Yoshihiko; Ohbayashi, Keiji; Onodera, Kaoru

1991-08-01

While silver halide photosensitive materials offer superiority in image quality -- both in color and black-and-white -- they require chemical solutions for processing, and this can be a drawback. To overcome this, researchers turned to the thermal development of silver halide photographic materials, and met their first success with black-and-white images. Later, with the development of the Konica Dry Color System, color images were finally obtained from a completely dry thermal development system, without the use of water or chemical solutions. The dry color system is characterized by a novel chromogenic color image-forming technology and comprises four processes. (1) With the application of heat, a color developer precursor (CDP) decomposes to generate a p-phenylenediamine color developer (CD). (2) The CD then develops silver salts. (3) Oxidized CD then reacts with couplers to generate color image dyes. (4) Finally, the dyes diffuse from the system's photosensitive sheet to its image-receiving sheet. The authors have analyzed the kinetics of each of the system's four processes. In this paper, they report the kinetics of the system's first process, color developer (CD) generation.

Manufacturing and testing of wavefront filters for DARWIN

NASA Astrophysics Data System (ADS)

Flatscher, R.; Artjushenko, V.; Sakharova, T.; Pereira do Carmo, Joao

2017-11-01

Wavefront filtering is mandatory in the realisation of nulling interferometers with high star light suppression capability required to detect extrasolar planets, such as the one foreseen for the ESA Darwin mission. This paper presents the design, manufacturing, and test results of single mode fibres to be used as wavefront filters in mid-infrared range. Fibres made from chalcogenide glass and silver halide crystals were produced. The first class can serve as wavefront filters up to a wavelength of 11 microns, while silver halide fibres can be used over the full Darwin wavelength range from 6.5 to 18 micron. The chalcogenide glass fibres were drawn by double crucible method whereas polycrystalline fibres from silver halides were fabricated by multiple extrusion from a crystalline preform. Multi-layer AR-coatings for fibre ends were developed and environmentally tested for both types of fibres. Special fibre facet polishing procedures were established, in particular for the soft silver halide fibre ends. Cable design and assembly process were also developed, including termination by SMA-connectors with ceramic ferrules and fibre protection by loose PEEK-tubings to prevent excessive bending and chemical attacks for fibres. The wavefront filtering capability of the fibres was demonstrated on a high quality Mach-Zehnder interferometer. Two different groups of laser sources were used to measure the wavefront filtering of the fibres by using a CO-laser for testing in the lower sub-band and a CO2-laser to check the upper sub-band. Measurements of the fibres far field intensity distribution and transmission were performed for numerous cable samples. Single mode behaviour was observed in more than 25 silver halide fibre cables before AR-coating of their ends, while after that 17 cables were compliant with all technical requirements. Residual cladding modes existing in short single mode fibres were effectively removed by applying of a proper absorbing jacket to the fibre's lateral surface and by adding an oversized output aperture in front of fibre ends. Several fibres were exposed to gamma radiation of total dose of 25, 50, and even 500 krad. No deterioration was found on AR-coated fibre ends and on fibre material. Five fibres were irradiated by proton radiation of 10MeV energy and 1010 p/cm2 equivalent fluence. Several fibres were cooled down to 10 K by plunging them in a dipstick into liquid Helium. Silver halide fibres survived that test when cables were properly assembled. The brittle chalcogenide glass fibres were much more sensitive to thermal gradients and the related cables did not survive the thermal shock. Critical issues have been revealed in multiple drawings of chalcogenide glass fibres where core and cladding composition were not stable at some fabrication stages - resulting in a poor single mode guiding. Much better results have been achieved with polycrystalline fibres from silver halides made with a small core and low NA and enabling single mode guiding in the mid infrared.

Ionic Liquids as Energetic Materials

DTIC Science & Technology

2007-03-01

triazolium halide that can be synthesized from the electrophilic fluorination and quaternization of the amino-substituted triazole. Metathesis with a...silver salt such as silver nitrate forms the nitrate salt. By electrophilic difluoroamination of 1 -alkyl-3-nitro- 1,2,4-triazole, 1,4-dialkyl-3-nitro...nonaromatic salts (1-7) described in Table 1. The presence of small amounts of fluorine in the substituent arm contributes to the thermal stability and has

Infrared evanescent field sensing with quantum cascade lasers and planar silver halide waveguides.

PubMed

Charlton, Christy; Katzir, Abraham; Mizaikoff, Boris

2005-07-15

We demonstrate the first midinfrared evanescent field absorption measurements with an InGaAs/AlInAs/InP distributed feedback (DFB) quantum cascade laser (QCL) light source operated at room temperature coupled to a free-standing, thin-film, planar, silver halide waveguide. Two different analytes, each matched to the emission frequency of a QCL, were investigated to verify the potential of this technique. The emission of a 1650 cm(-1) QCL overlaps with the amide absorption band of urea, which was deposited from methanol solution, forming urea crystals at the waveguide surface after solvent evaporation. Solid urea was detected down to 80.7 microg of precipitate at the waveguide surface. The emission frequency of a 974 cm(-1) QCL overlaps with the CH3-C absorption feature of acetic anhydride. Solutions of acetic anhydride in acetonitrile have been detected down to a volume of 0.01 microL (10.8 microg) of acetic anhydride solution after deposition at the planar waveguide (PWG) surface. Free-standing, thin-film, planar, silver halide waveguides were produced by press-tapering heated, cylindrical, silver halide fiber segments to create waveguides with a thickness of 300-190 microm, a width of 3 mm, and a length of 35 mm. In addition, Fourier transform infrared (FT-IR) evanescent field absorption measurements with planar silver halide waveguides and transmission absorption QCL measurements verify the obtained results.

Formation of random and regular relief-phase structures on silver halide photographic emulsions by holographic methods

NASA Astrophysics Data System (ADS)

Ganzherli, N. M.; Gulyaev, S. N.; Gurin, A. S.; Kramushchenko, D. D.; Maurer, I. A.; Chernykh, D. F.

2009-07-01

The formation of diffusers and microlens rasters on silver halide emulsions by holographic methods is considered. Two techniques for converting amplitude holographic recording to relief-phase recording, selective curing and irradiation of the emulsion gelatin by short-wavelength UV radiation, are compared.

Ab initio calculations of the lattice dynamics of silver halides

NASA Astrophysics Data System (ADS)

Gordienko, A. B.; Kravchenko, N. G.; Sedelnikov, A. N.

2010-12-01

Based on ab initio pseudopotential calculations, the results of investigations of the lattice dynamics of silver halides AgHal (Hal = Cl, Br, I) are presented. Equilibrium lattice parameters, phonon spectra, frequency densities and effective atomic-charge values are obtained for all types of crystals under study.

Holographic recording materials - A review

NASA Technical Reports Server (NTRS)

Kurtz, R. L.; Owen, R. B.

1975-01-01

Holographic recording materials in current use are examined along with a few of their applications. Some experimental media are also studied. No effort is made to rank the commercial materials, since satisfactory results can be obtained with any of them. The discussion covers silver halide plates and films, photoresists, thermoplastics, photopolymers, dichromated gelatin, photochromic materials, electrooptical crystals, styryl free radical film, and TEP film. A convenient summation of some material properties is presented in tabular form.

36 CFR § 1254.108 - What are NARA's requirements for the microfilming process?

Code of Federal Regulations, 2013 CFR

2013-07-01

... you leave unattended. (j) We inspect the microform output at scheduled intervals during the project to... images, you must provide NARA with a silver halide duplicate negative upon completion of the project. When the project involves more than 10,000 images, you must provide a silver halide duplicate negative...

Holographic diffuser by use of a silver halide sensitized gelatin process

NASA Astrophysics Data System (ADS)

Kim, Sun Il; Choi, Yoon Sun; Ham, Yong Nam; Park, Chong Yun; Kim, Jong Man

2003-05-01

Diffusers play an important role in liquid-crystal display (LCD) application as a beam-shaping device, a brightness homogenizer, a light-scattering device, and an imaging screen. The transmittance and diffusing angle of the diffusers are the critical aspects for the applications to the LCD. The holographic diffusers by use of various processing methods have been investigated. The diffusing characteristics of different diffusing materials and processing methods have been evaluated and compared. The micro-structures of holographic diffusers have been investigated by use of using scanning electron microscopy. The holographic diffusers by use of the silver halide sensitized gelatin (SHSG) method have the structural merits for the improvement of the quality of diffusers. The features of holographic diffuser were exceptional in terms of transmittance and diffusing angle. The replication method by use of the SHSG process can be directly used for the manufacturing of diffusers for the display application.

Electronic Devices with Diffusion Barrier and Process for Making Same

DTIC Science & Technology

2001-05-09

conductivity metallization materials such as gold , silver, and platinum. As can be appreciated from the foregoing, a barrier film is needed which... gold ), as well as platinum. These metals are highly attractive 10 for interconnect strategies on account of there intrinsic low resistivity and...the monolayer portion of the barrier -7- material. The monolayer ( monoatomic ) layer of metal atoms and the homoepitaxial film of metal halide

An investigation and conceptual design of a holographic starfield and landmark tracker

NASA Technical Reports Server (NTRS)

Welch, J. D.

1973-01-01

The analysis, experiments, and design effort of this study have supported the feasibility of the basic holographic tracker concept. Image intensifiers and photoplastic recording materials were examined, along with a Polaroid rapid process silver halide material. Two reference beam, coherent optical matched filter technique was used for multiplexing spatial frequency filters for starfields. A 1 watt HeNe laser and an electro-optical readout are also considered.

Passive particle dosimetry. [silver halide crystal growth

NASA Technical Reports Server (NTRS)

Childs, C. B.

1977-01-01

Present methods of dosimetry are reviewed with emphasis on the processes using silver chloride crystals for ionizing particle dosimetry. Differences between the ability of various crystals to record ionizing particle paths are directly related to impurities in the range of a few ppm (parts per million). To understand the roles of these impurities in the process, a method for consistent production of high purity silver chloride, and silver bromide was developed which yields silver halides with detectable impurity content less than 1 ppm. This high purity silver chloride was used in growing crystals with controlled doping. Crystals were grown by both the Czochalski method and the Bridgman method, and the Bridgman grown crystals were used for the experiments discussed. The distribution coefficients of ten divalent cations were determined for the Bridgman crystals. The best dosimeters were made with silver chloride crystals containing 5 to 10 ppm of lead; other impurities tested did not produce proper dosimeters.

Phase recording for formation of holographic optical elements on silver-halide photographic emulsions

NASA Astrophysics Data System (ADS)

Ganzherli, Nina M.; Gulyaev, Sergey N.; Maurer, Irina A.; Chernykh, Dmitrii F.

2009-05-01

Holographic fabrication methods of regular and nonregular relief-phase structures on silver-halide photographic emulsions are considered. Methods of gelatin photodestruction under short-wave ultra-violet radiation and chemical hardening with the help of dichromated solutions were used as a technique for surface relief formation. The developed techniques permitted us to study specimens of holographic diffusers and microlens rasters with small absorption and high light efficiency.

A Technical, User and Cost Comparison Study of Microfiche Duplicate Film Material. Final Report.

ERIC Educational Resources Information Center

Prevel, James J.

A technical, user and cost comparison study was undertaken to provide the Educational Resources Information Clearinghouse (ERIC) staff with data on silver halide, diazo, and vesicular type films for microfiche duplication. This information will allow ERIC to determine if diazo and/or vesicular films should be considered in producing ERIC duplicate…

Chemical Origin of the Stability Difference between Copper(I)- and Silver(I)-Based Halide Double Perovskites.

PubMed

Xiao, Zewen; Du, Ke-Zhao; Meng, Weiwei; Mitzi, David B; Yan, Yanfa

2017-09-25

Recently, Cu I - and Ag I -based halide double perovskites have been proposed as promising candidates for overcoming the toxicity and instability issues inherent within the emerging Pb-based halide perovskite absorbers. However, up to date, only Ag I -based halide double perovskites have been experimentally synthesized; there are no reports on successful synthesis of Cu I -based analogues. Here we show that, owing to the much higher energy level for the Cu 3d 10 orbitals than for the Ag 4d 10 orbitals, Cu I atoms energetically favor 4-fold coordination, forming [CuX 4 ] tetrahedra (X=halogen), but not 6-fold coordination as required for [CuX 6 ] octahedra. In contrast, Ag I atoms can have both 6- and 4-fold coordinations. Our density functional theory calculations reveal that the synthesis of Cu I halide double perovskites may instead lead to non-perovskites containing [CuX 4 ] tetrahedra, as confirmed by our material synthesis efforts. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Gelatin Layer Film with Gold Clusters in Using Photographic Film

NASA Astrophysics Data System (ADS)

Kuge, Ken'ichi; Arisawa, Michiko; Aoki, Naokazu; Hasegawa, Akira

2000-12-01

A gelatin layer film with gold clusters is produced by taking advantage of the photosensitivity of silver halide photography. Through exposure silver specks, which are called latent-image specks and are composed of several reduced silver atoms, are formed on the surface of silver halide grains in the photographic film. As the latent-image specks act as a catalyst for redox reaction, reduced gold atoms are deposited on the latent-image specks when the exposed film is immersed in a gold (I) thiocyanate complex solution for 5-20 days. Subsequently, when the silver halide grains are dissolved and removed, the gelatin layer film with gold clusters remains. The film produced by this method is purple and showed an absorption spectrum having a maximum of approximately 560 nm as a result of plasmon absorption. The clusters continued to grow with immersion time, and the growth rate increased as the concentration of the gold complex solution was increased. The cluster diameter changed from 20 nm to 100 nm. By this method, it is possible to produce a gelatin film of a large area with evenly dispersed gold clusters, and since it is produced only on the exposed area, pattern forming is also possible.

Memory preservation made prestigious but easy

NASA Astrophysics Data System (ADS)

Fageth, Reiner; Debus, Christina; Sandhaus, Philipp

2011-01-01

Preserving memories combined with story-telling using either photo books for multiple images or high quality products such as one or a few images printed on canvas or images mounted on acryl to create high-quality wall decorations are gradually becoming more popular than classical 4*6 prints and classical silver halide posters. Digital printing via electro photography and ink jet is increasingly replacing classical silver halide technology as the dominant production technology for these kinds of products. Maintaining a consistent and comparable quality of output is becoming more challenging than using silver halide paper for both, prints and posters. This paper describes a unique approach of combining both desktop based software to initiate a compelling project and the use of online capabilities in order to finalize and optimize that project in an online environment in a community process. A comparison of the consumer behavior between online and desktop based solutions for generating photo books will be presented.

The surface structure of silver-coated gold nanocrystals and its influence on shape control

DOE PAGES

Padmos, J. Daniel; Personick, Michelle L.; Tang, Qing; ...

2015-07-08

Understanding the surface structure of metal nanocrystals with specific facet indices is important due to its impact on controlling nanocrystal shape and functionality. However, this is particularly challenging for halide-adsorbed nanocrystals due to the difficulty in analysing interactions between metals and light halides (for example, chloride). Here we uncover the surface structures of chloride-adsorbed, silver-coated gold nanocrystals with {111}, {110}, {310} and {720} indexed facets by X-ray absorption spectroscopy and density functional theory modelling. The silver–chloride, silver–silver and silver–gold bonding structures are markedly different between the nanocrystal surfaces, and are sensitive to their formation mechanism and facet type. A uniquemore » approach of combining the density functional theory and experimental/simulated X-ray spectroscopy further verifies the surface structure models and identifies the previously indistinguishable valence state of silver atoms on the nanocrystal surfaces. Overall, this work elucidates the thus-far unknown chloride–metal nanocrystal surface structures and sheds light onto the halide-induced growth mechanism of anisotropic nanocrystals.« less

Microform Film Stock: A Hobson's Choice. Are Librarians Getting the Worst of Both Worlds? (and) Microfilm Types: There Really Is a Choice.

ERIC Educational Resources Information Center

Dupont, Jerry; Dodson, Suzanne Cates

1986-01-01

Two articles summarize qualities of medium being used in production of microforms: silver halide film, diazo film, and vesicular film. Highlights include policy of Law Library Microform Consortium, a nonprofit library cooperative and major supplier of legal materials on microfiche; archival storage and preservation; and recent recommendations.…

SLR digital camera for forensic photography

NASA Astrophysics Data System (ADS)

Har, Donghwan; Son, Youngho; Lee, Sungwon

2004-06-01

Forensic photography, which was systematically established in the late 19th century by Alphonse Bertillon of France, has developed a lot for about 100 years. The development will be more accelerated with the development of high technologies, in particular the digital technology. This paper reviews three studies to answer the question: Can the SLR digital camera replace the traditional silver halide type ultraviolet photography and infrared photography? 1. Comparison of relative ultraviolet and infrared sensitivity of SLR digital camera to silver halide photography. 2. How much ultraviolet or infrared sensitivity is improved when removing the UV/IR cutoff filter built in the SLR digital camera? 3. Comparison of relative sensitivity of CCD and CMOS for ultraviolet and infrared. The test result showed that the SLR digital camera has a very low sensitivity for ultraviolet and infrared. The cause was found to be the UV/IR cutoff filter mounted in front of the image sensor. Removing the UV/IR cutoff filter significantly improved the sensitivity for ultraviolet and infrared. Particularly for infrared, the sensitivity of the SLR digital camera was better than that of the silver halide film. This shows the possibility of replacing the silver halide type ultraviolet photography and infrared photography with the SLR digital camera. Thus, the SLR digital camera seems to be useful for forensic photography, which deals with a lot of ultraviolet and infrared photographs.

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(-)-myrtenol nitrate.

PubMed

Bew, Sean P; Hiatt-Gipson, Glyn D; Mills, Graham P; Reeves, Claire E

2016-01-01

Here we report the chemoselective synthesis of several important, climate relevant isoprene nitrates using silver nitrate to mediate a 'halide for nitrate' substitution. Employing readily available starting materials, reagents and Horner-Wadsworth-Emmons chemistry the synthesis of easily separable, synthetically versatile 'key building blocks' (E)- and (Z)-3-methyl-4-chlorobut-2-en-1-ol as well as (E)- and (Z)-1-((2-methyl-4-bromobut-2-enyloxy)methyl)-4-methoxybenzene has been achieved using cheap, 'off the shelf' materials. Exploiting their reactivity we have studied their ability to undergo an 'allylic halide for allylic nitrate' substitution reaction which we demonstrate generates (E)- and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate, and (E)- and (Z)-2-methyl-4-hydroxybut-2-enyl nitrates ('isoprene nitrates') in 66-80% overall yields. Using NOESY experiments the elucidation of the carbon-carbon double bond configuration within the purified isoprene nitrates has been established. Further exemplifying our 'halide for nitrate' substitution chemistry we outline the straightforward transformation of (1R,2S)-(-)-myrtenol bromide into the previously unknown monoterpene nitrate (1R,2S)-(-)-myrtenol nitrate.

Development of a 2-channel embedded infrared fiber-optic temperature sensor using silver halide optical fibers.

PubMed

Yoo, Wook Jae; Jang, Kyoung Won; Seo, Jeong Ki; Moon, Jinsoo; Han, Ki-Tek; Park, Jang-Yeon; Park, Byung Gi; Lee, Bongsoo

2011-01-01

A 2-channel embedded infrared fiber-optic temperature sensor was fabricated using two identical silver halide optical fibers for accurate thermometry without complicated calibration processes. In this study, we measured the output voltages of signal and reference probes according to temperature variation over a temperature range from 25 to 225 °C. To decide the temperature of the water, the difference between the amounts of infrared radiation emitted from the two temperature sensing probes was measured. The response time and the reproducibility of the fiber-optic temperature sensor were also obtained. Thermometry with the proposed sensor is immune to changes if parameters such as offset voltage, ambient temperature, and emissivity of any warm object. In particular, the temperature sensing probe with silver halide optical fibers can withstand a high temperature/pressure and water-chemistry environment. It is expected that the proposed sensor can be further developed to accurately monitor temperature in harsh environments.

Refractive microlensarray made of silver-halide sensitized gelatin (SHSG) etched by enzyme with SLM-based lithography

NASA Astrophysics Data System (ADS)

Guo, Xiaowei; Chen, Mingyong; Zhu, Jianhua; Ma, Yanqin; Du, Jinglei; Guo, Yongkang; Du, Chunlei

2006-01-01

A novel method for the fabrication of continuous micro-optical components is presented in this paper. It employs a computer controlled digital-micromirror-device(DMD TM) as a switchable projection mask and silver-halide sensitized gelatin (SHSG) as recording material. By etching SHSG with enzyme solution, the micro-optical components with relief modulation can be generated through special processing procedures. The principles of etching SHSG with enzyme and theoretical analysis for deep etching are also discussed in detail, and the detailed quantitative experiments on the processing procedures are conducted to determine optimum technique parameters. A good linear relationship within a depth range of 4μm was experimentally obtained between exposure dose and relief depth. At last, the microlensarray with 256.8μm radius and 2.572μm depth was achieved. This method is simple, cheap and the aberration in processing procedures can be corrected in the step of designing mask, so it is a practical method to fabricate good continuous profile for low-volume production.

An objective protocol for comparing the noise performance of silver halide film and digital sensor

NASA Astrophysics Data System (ADS)

Cao, Frédéric; Guichard, Frédéric; Hornung, Hervé; Tessière, Régis

2012-01-01

Digital sensors have obviously invaded the photography mass market. However, some photographers with very high expectancy still use silver halide film. Are they only nostalgic reluctant to technology or is there more than meets the eye? The answer is not so easy if we remark that, at the end of the golden age, films were actually scanned before development. Nowadays film users have adopted digital technology and scan their film to take advantage from digital processing afterwards. Therefore, it is legitimate to evaluate silver halide film "with a digital eye", with the assumption that processing can be applied as for a digital camera. The article will describe in details the operations we need to consider the film as a RAW digital sensor. In particular, we have to account for the film characteristic curve, the autocorrelation of the noise (related to film grain) and the sampling of the digital sensor (related to Bayer filter array). We also describe the protocol that was set, from shooting to scanning. We then present and interpret the results of sensor response, signal to noise ratio and dynamic range.

Correlation of Electrode Kinetics with Surface Structure.

DTIC Science & Technology

1980-09-01

platinum and gold electrodes is sufficiently strong so that monolayers are formed upon contact even with small (millimolar) bulk iodide concentrations...transition-metal reactants, we have monitored the effects of altering the electrode material from mercury to silver, platinum, and gold upon the...strikingly different behavior for the reduction of Co III(NH3)5X and Co II(en)2X2 at platinum and gold electrodes. 1 0 For halide bridging ligands (X

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

PubMed Central

Hiatt-Gipson, Glyn D; Mills, Graham P; Reeves, Claire E

2016-01-01

Summary Here we report the chemoselective synthesis of several important, climate relevant isoprene nitrates using silver nitrate to mediate a ’halide for nitrate’ substitution. Employing readily available starting materials, reagents and Horner–Wadsworth–Emmons chemistry the synthesis of easily separable, synthetically versatile ‘key building blocks’ (E)- and (Z)-3-methyl-4-chlorobut-2-en-1-ol as well as (E)- and (Z)-1-((2-methyl-4-bromobut-2-enyloxy)methyl)-4-methoxybenzene has been achieved using cheap, ’off the shelf’ materials. Exploiting their reactivity we have studied their ability to undergo an ‘allylic halide for allylic nitrate’ substitution reaction which we demonstrate generates (E)- and (Z)-3-methyl-4-hydroxybut-2-enyl nitrate, and (E)- and (Z)-2-methyl-4-hydroxybut-2-enyl nitrates (‘isoprene nitrates’) in 66–80% overall yields. Using NOESY experiments the elucidation of the carbon–carbon double bond configuration within the purified isoprene nitrates has been established. Further exemplifying our ‘halide for nitrate’ substitution chemistry we outline the straightforward transformation of (1R,2S)-(−)-myrtenol bromide into the previously unknown monoterpene nitrate (1R,2S)-(−)-myrtenol nitrate. PMID:27340495

Advances with holographic DESA emulsions

NASA Astrophysics Data System (ADS)

Dünkel, Lothar; Eichler, Jürgen; Schneeweiss, Claudia; Ackermann, Gerhard

2006-02-01

DESA emulsions represent layer systems based on ultra-fine grained silver halide (AgX) technology. The new layers have an excellent performance for holographic application. The technology has been presented repeatedly in recent years, including the emulsion characterization and topics of chemical and spectral sensitization. The paper gives a survey of actual results referring to panchromatic sensitization and other improvements like the application of silver halide sensitized gelatine (SHSG) procedure. These results are embedded into intensive collaborations with small and medium enterprises (SME's) to commercialize DESA layers. Predominant goals are innovative products with holographic components and layers providing as well as cost effectiveness and high quality.

Anomalous D-Log E curve with high contrast developer Kodak D8 on ultra fine grain emulsion BB640.

PubMed

Ulibarrena, M; Mendez, M; Blaya, S; Fimia, A

2001-12-03

D-Log E curves, also known as H-D curves, are used since the XIX century as a tool for describing the characteristics of silver halide emulsions. This curve has a very standard shape, with a linear region, a toe, a shoulder and a solarization region. In this work we present a distortion of the usual curve due to the action of a high contrast developer, Kodak D8, on an ultra fine grain emulsion, BB640\\cite{ov04}. The solarization effect is replaced by a linear zone where developed densities increase with increasing exposures, until all silver halide present in the emulsion is reduced by developer D8 to metallic silver. Densities higher than 11 have been obtained.

Kicking the Silver Habit: Confessions of a Former Addict.

ERIC Educational Resources Information Center

Spaulding, Carl M.

1978-01-01

Reviews and compares three types of microfilm--silver halide, diazo, and vesicular. Storage and handing requirements for permanent collections are discussed, and some suggestions are offered to solve problems caused by the proliferation of nonsilver films in libraries. (MBR)

Silver halide sensitized gelatin process effects in holographic lenses recorded on Slavich PFG-01 plates

NASA Astrophysics Data System (ADS)

Collados, Maria Victoria; Arias, Isabel; García, Ana; Atencia, Jesús; Quintanilla, Manuel

2003-02-01

In this work we study the feasibility of using silver halide sensitized gelatin based on PFG-01 (Slavich) emulsions to construct uniaxial compound lenses. This processing is able to introduce variations in the thickness and refractive index of the emulsion. We prove that these changes are not sufficient to provide the observed variations in Bragg conditions in the reconstruction and that a shear-type effect must exist to explain the performance of processed emulsions. We study the characteristics of a compound lens, obtaining acceptable image quality, good resolution, and the typical field limitation of volume holographic elements.

Recent progress on mid-IR sensing with optical fibers

NASA Astrophysics Data System (ADS)

Kellner, Robert A.; Gobel, R.; Goetz, R.; Lendl, B.; Edl-Mizaikoff, B.; Tacke, Maurus; Katzir, Abraham

1995-09-01

Chemical sensors are analytical systems for the evaluation of compound- or ion-specific or - selective signals produced by specific or selective chemical reactions taking place at the interface between the chemically modified sensor surface and the substrate. The well known electrochemical sensing schemes have greatly contributed that sensors are considered now as the 'third supporting pillar of analytical chemistry' besides chromatography and spectroscopy. The aim of this paper is to describe the novel capabilities of chemical modified IR-transparent fibers as chemical IR-sensors for the on-line analysis of chlorinated hydrocarbons and organic compounds in aqueous solutions and gaseous mixtures, glucose, and sucrose in aqueous solution as developed in our laboratory. Moreover, the relative merits of this new method wil be depicted in comparison to other sensing techniques. Optical fiber sensors are novel analysis systems, based on molecular spectroscopy in the UV/VIS/IR-range. They benefit from the tremendous development in the field of optical fibers, an offspring of the telecommunication industry and the electronic revolution during the last few years. With the development of new materials besides the well known quartz fibers for the UV/VIS/NIR-range the optical window for fiber optic sensors was enlarged from 0,2 to 20 micrometers recently. The fiber length was increased recently to up to 2 meters for silver halides and approximately 10 meters for chalcogenides. New applications for environmental, food, and clinical sensing as well as process analysis are the driving force for modern research in IR-optical fiber sensors using mainly sapphire (Al2O3), chalcogenide (As-Se-Te) and silver halide (AgBr/AgCl) fibers and flow injection analysis (FIA) systems. Few representative examples for each of the various optical sensor types will be presented. Particular attention will be given to the use of silver halide fibers for the simultaneous determination of traces of chlorinated hydrocarbons in water and to FIA-systems for the process analysis of beverages.

Silver ion bactericide system. [for Space Shuttle Orbiter potable water

NASA Technical Reports Server (NTRS)

Jasionowski, W. J.; Allen, E. T.

1974-01-01

Description of a preliminary flight prototype system which uses silver ions as the bactericide to preserve sterility of the water used for human consumption and hygiene in the Space Shuttle Orbiter. The performance of silver halide columns for passively dosing fuel cell water with silver ions is evaluated. Tests under simulated Orbiter mission conditions show that silver ion doses of 0.05 ppm are bactericidal for Pseudomonas aeruginosa and Type IIIa, the two bacteria found in Apollo potable water systems. The design of the Advance Prototype Silver Ion Water Bactericide System now under development is discussed.

Fabrication of large area plasmonic nanoparticle grating structure on silver halide based transmission electron microscope film and its application as a surface enhanced Raman spectroscopy substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Singh, M. N.

The plasmonic responses of silver nanoparticle grating structures of different periods made on silver halide based electron microscope film are investigated. Raster scan of the conventional scanning electron microscope (SEM) is used to carry out electron beam lithography for fabricating the plasmonic nanoparticle grating (PNG) structures. Morphological characterization of the PNG structures, carried out by the SEM and the atomic force microscope, indicates that the depth of the groove decreases with a decrease in the grating period. Elemental characterization performed by the energy dispersive spectroscopy and the x-ray diffraction shows the presence of nanoparticles of silver in the PNG grating.more » The optical characterization of the gratings shows that the localized surface plasmon resonance peak shifts from 366 to 378 nm and broadens with a decrease in grating period from 10 to 2.5 μm. The surface enhanced Raman spectroscopy of the Rhodamine-6G dye coated PNG structure shows the maximum enhancement by two orders of magnitude in comparison to the randomly distributed silver nanoparticles having similar size and shape as the PNG structure.« less

Diffraction efficiency of plasmonic gratings fabricated by electron beam lithography using a silver halide film

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in, E-mail: sudheer.rrcat@gmail.com; Tiwari, P.; Srivastava, Himanshu

2016-07-28

The silver nanoparticle surface relief gratings of ∼10 μm period are fabricated using electron beam lithography on the silver halide film substrate. Morphological characterization of the gratings shows that the period, the shape, and the relief depth in the gratings are mainly dependent on the number of lines per frame, the spot size, and the accelerating voltage of electron beam raster in the SEM. Optical absorption of the silver nanoparticle gratings provides a broad localized surface plasmon resonance peak in the visible region, whereas the intensity of the peaks depends on the number density of silver nanoparticles in the gratings. Themore » maximum efficiency of ∼7.2% for first order diffraction is observed for the grating fabricated at 15 keV. The efficiency is peaking at 560 nm with ∼380 nm bandwidth. The measured profiles of the diffraction efficiency for the gratings are found in close agreement with the Raman-Nath diffraction theory. This technique provides a simple and efficient method for the fabrication of plasmonic nanoparticle grating structures with high diffraction efficiency having broad wavelength tuning.« less

Understanding the Effects of NaCl, NaBr and Their Mixtures on Silver Nanowire Nucleation and Growth in Terms of the Distribution of Electron Traps in Silver Halide Crystals

PubMed Central

Rui, Yunjun; Zhao, Weiliang; Zhu, Dewei; Wang, Hengyu; Song, Guangliang; Swihart, Mark T.; Wan, Neng; Gu, Dawei; Tang, Xiaobing; Yang, Ying; Zhang, Tianyou

2018-01-01

In recent years, many research groups have synthesized ultra-thin silver nanowires (AgNWs) with diameters below 30 nm by employing Cl− and Br− simultaneously in the polyol process. However, the yield of AgNWs in this method was low, due to the production of Ag nanoparticles (AgNPs) as an unwanted byproduct, especially in the case of high Br− concentration. Here, we investigated the roles of Cl− and Br− in the preparation of AgNWs and then synthesized high aspect ratio (up to 2100) AgNWs in high yield (>85% AgNWs) using a Cl− and Br− co-mediated method. We found that multiply-twinned particles (MTPs) with different critical sizes were formed and grew into AgNWs, accompanied by a small and large amount of AgNPs for the NaCl and NaBr additives, respectively. For the first time, we propose that the growth of AgNWs of different diameters and yields can be understood based on the electron trap distribution (ETD) of the silver halide crystals. For the case of Cl− and Br− co-additives, a mixed silver halide crystal of AgBr1−xClx was formed, rather than the AgBr/AgCl mixture reported previously. In this type of crystal, the ETD is uniform, which is beneficial for the synthesis of AgNWs with small diameter (30~40 nm) and high aspect ratio. AgNW transparent electrodes were prepared in air by rod coating. A sheet resistance of 48 Ω/sq and transmittance of 95% at 550 nm were obtained without any post-treatment. PMID:29538281

Point of zero potential of single-crystal electrode/inert electrolyte interface.

PubMed

Zarzycki, Piotr; Preočanin, Tajana

2012-03-15

Most of the environmentally important processes occur at the specific hydrated mineral faces. Their rates and mechanisms are in part controlled by the interfacial electrostatics, which can be quantitatively described by the point of zero potential (PZP). Unfortunately, the PZP value of specific crystal face is very difficult to be experimentally determined. Here we show that PZP can be extracted from a single-crystal electrode potentiometric titration, assuming the stable electrochemical cell resistivity and lack of specific electrolyte ions sorption. Our method is based on determining a common intersection point of the electrochemical cell electromotive force at various ionic strengths, and it is illustrated for a few selected surfaces of rutile, hematite, silver chloride, and bromide monocrystals. In the case of metal oxides, we have observed the higher PZP values than those theoretically predicted using the MultiSite Complexation Model (MUSIC), that is, 8.4 for (001) hematite (MUSIC-predicted ~6), 8.7 for (110) rutile (MUSIC-predicted ~6), and about 7 for (001) rutile (MUSIC-predicted 6.6). In the case of silver halides, the order of estimated PZP values (6.4 for AgCl<6.5 for AgBr) agrees well with sequence estimated from the silver halide solubility products; however, the halide anions (Cl(-), Br(-)) are attracted toward surface much stronger than the Ag(+) cations. The observed PZPs sequence and strong anions affinity toward silver halide surface can be correlated with ions hydration energies. Presented approach is the complementary one to the hysteresis method reported previously [P. Zarzycki, S. Chatman, T. Preočanin, K.M. Rosso, Langmuir 27 (2011) 7986-7990]. A unique experimental characterization of specific crystal faces provided by these two methods is essential in deeper understanding of environmentally important processes, including migration of heavy and radioactive ions in soils and groundwaters. Copyright © 2012 Elsevier Inc. All rights reserved.

Sorption of silver, gold and palladium with a polythioether foam.

PubMed

Khan, A S; Chow, A

1986-02-01

Silver, gold and palladium can be sorbed by a thiopolymer of the type [HO(CH(2)CH(2)CH(2)SS)(n)CH(2)CH(2)OH]. The distribution coefficient for palladium increases with halide concentration, with iodide having the largest effect. Silver can be extracted from chloride, nitrate or picrate media. The different distribution coefficients for gold in hydrochloric acid and in sodium chloride suggest that different sorption mechanisms predominate.

Fully Printed Halide Perovskite Light-Emitting Diodes with Silver Nanowire Electrodes.

PubMed

Bade, Sri Ganesh R; Li, Junqiang; Shan, Xin; Ling, Yichuan; Tian, Yu; Dilbeck, Tristan; Besara, Tiglet; Geske, Thomas; Gao, Hanwei; Ma, Biwu; Hanson, Kenneth; Siegrist, Theo; Xu, Chengying; Yu, Zhibin

2016-02-23

Printed organometal halide perovskite light-emitting diodes (LEDs) are reported that have indium tin oxide (ITO) or carbon nanotubes (CNTs) as the transparent anode, a printed composite film consisting of methylammonium lead tribromide (Br-Pero) and poly(ethylene oxide) (PEO) as the emissive layer, and printed silver nanowires as the cathode. The fabrication can be carried out in ambient air without humidity control. The devices on ITO/glass have a low turn-on voltage of 2.6 V, a maximum luminance intensity of 21014 cd m(-2), and a maximum external quantum efficiency (EQE) of 1.1%, surpassing previous reported perovskite LEDs. The devices on CNTs/polymer were able to be strained to 5 mm radius of curvature without affecting device properties.

Residence of silver in mineral deposits of the Thunder Mountain caldera complex, Central Idaho, U.S.A.

USGS Publications Warehouse

Leonard, B.F.; Christian, R.P.

1987-01-01

Silver is an accessory element in gold, antimony, and tungsten deposits of the caldera complex. Most of the deposits are economically of low grade and genetically of xenothermal or epithermal character. Their gold- and silver-bearing minerals are usually disseminated, fine grained, and difficult to study. Sparsely disseminated pyrite and arsenoprite are common associates. Identified silver minerals are: native silver and electrum; the sulfides acanthite, argentite (the latter always inverted to acanthite), and members of the Silberkies group; the sulfosalts matildite, miargyrite, pyrargyrite, argentian tetrahedrite, and unnamed Ag-Sb-S and Ag-Fe-Sb-S minerals; the telluride hessite and the selenide naumannite; halides of the cerargyrite group; and the antimonate stetefeldtite. Suspected silver minerals include the sulfide uytenbogaardtite and the sulfosalts andorite, diaphorite, and polybasite. Electrum, acanthite, and argentian tetrahedrite are common, though nowhere abundant. The other silver minerals are rare. Silver is present as a minor element in the structure of some varieties of other minerals. These include arsenopyrite, chalcopyrite, chalcostibite, covelline, digenite, galena, sphalerite, and stibnite. The search for adventitious Ag in most of these minerals has been cursory. The results merely indicate that elemental silver is not confined to discrete silver minerals and is, therefore, an additional complication for the recovery of silver-bearing material from some deposits. Silver occurs cryptically in some plants of the region. At Red Mountain, for example, the ashed sapwood of Douglas-fir (Pseudotsuga menziesii) contains 2 to 300 ppm Ag. Silver in the ashed wood is roughly 100 times as abundant as it is in soil. The phenomenon, useful in biogeochemical exploration, deserves the attention of mineralogists. ?? 1987 Springer-Verlag.

Research on copying system of dynamic multiplex holographic stereograms

NASA Astrophysics Data System (ADS)

Fu, Huaiping; Yang, Hong; Zheng, Tong

2003-05-01

The most important advantage of holographic stereograms over conventional hologram is that they can produce 3D images at any desired scale with movement, holographers in many countries involved in the studies towards it. We began our works in the early 80's and accomplished two research projects automatic system for making synthetic holograms and multiplex synthetic rainbow holograms, Based on these works, a large scale holographic stereogram of an animated goldfish was made by us for practical advertisement. In order to meet the needs of the market, a copying system for making multiplex holographic stereograms, and a special kind of silver halide holographic film developed by us recently. The characteristic of the copying system and the property of the special silver-halide emulsion are introduced in this paper.

Color silver halide hologram production and mastering

NASA Astrophysics Data System (ADS)

Bjelkhagen, Hans I.; Huang, Qiang

1997-04-01

Color reflection holograms recorded with the Denisyuk geometry have been demonstrated by the recently formed HOLOS Corporation in New Hampshire. The Slavich red-green-blue (RGB) sensitized ultra-high resolution silver halide emulsion was used for the hologram recording. The employed laser wavelengths were 647 nm, 532 nm, and 476 nm, generated by an argon ion, a frequency doubled Nd:YAG, and a krypton ion laser, respectively. A beam combination mechanism with dichroic filters enabled a simultaneous RGB exposure, which made the color balance and overall exposure energy easy to control as well as simplifying the recording procedure. HOLOS has been producing limited edition color holograms in various sizes from 4' X 5' to 12' X 16'. A 30 foot long optical table and high power lasers will enable HOLOS to record color holograms up to the size of one meter square in the near future. Various approaches have been investigated in generating color hologram masters which have sufficiently high diffraction efficiency to contact copy the color images onto photopolymer materials. A specially designed test object including the 1931 CIE chromaticity diagram, a rainbow ribbon cable, pure yellow dots, and a cloisonne elephant was used for color recording experiments. In addition, the Macbeth Color Checker chart was used. Both colorimetric evaluation and scattering noise measurements were performed using the PR-650 Photo Research SpectraScan SpectraCalorimeter.

A History of the Chemical Innovations in Silver-Halide Materials for Color PhotographyII. Color-Forming Development, Part 5. Coupler Innovations after the 1970's—Two-Equivalent Coupler and DIR Coupler

NASA Astrophysics Data System (ADS)

Oishi, Yasushi

After the 1970's on, several manufacturers including Fuji Film, Konica and Agfa-Gevaert participated in innovating color photographic materials by adding their own coupler chemistry to the technological architecture built by Kodak before then. One area of their major advances was development of the couplers having a coupling-off organic group. One of their functional forms was two-equivalent coupler which made the dye-forming process efficient and made the photosensitive layers slim. And another was DIR coupler which improved dramatically the image quality of color negative materials. In this paper a historical overview of these innovations is constructed from the technical documents, mainly patents.

Information recovery from high-speed silver halide emulsions containing CRT traces after exposure to nuclear gamma radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dittmore, C. H.

1974-03-01

A data recovery problem often occurs in nuclear tests when photographic film used to record CRT traces is unavoidably exposed fo gamma rays before it can be retrieved for developing. Studies made to improve recovery of the CRT data from such film are described. Best results were obtained with a procedure involving reversal processing, silver intensification, dye-coupling development, and duplication. (auth)

DOE Office of Scientific and Technical Information (OSTI.GOV)

King, W.A.; Kubas, G.J.

The present invention provides: a composition of the formula M{sup +x}(Ga(Y){sub 4}{sup {minus}}){sub x} where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R){sub x}Q{sup +}Ga(Y){sub 4}{sup {minus}} where Q is selected from themore » group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M{sup +x}{sub y}[X(GaY{sub 3}){sub z}]{sup {minus}y}{sub x} where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.« less

Gallium based low-interaction anions

DOEpatents

King, Wayne A.; Kubas, Gregory J.

2000-01-01

The present invention provides: a composition of the formula M.sup.+x (Ga(Y).sub.4.sup.-).sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; a composition of the formula (R).sub.x Q.sup.+ Ga(Y).sub.4.sup.- where Q is selected from the group consisting of carbon, nitrogen, sulfur, phosphorus and oxygen, each R is a ligand selected from the group consisting of alkyl, aryl, and hydrogen, x is an integer selected from the group consisting of 3 and 4 depending upon Q, and each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide; an ionic polymerization catalyst composition including an active cationic portion and a gallium based weakly coordinating anion; and bridged anion species of the formula M.sup.+x.sub.y [X(Ga(Y.sub.3).sub.z ].sup.-y.sub.x where M is a metal selected from the group consisting of lithium, sodium, potassium, magnesium, cesium, calcium, strontium, thallium, and silver, x is an integer selected from the group consisting of 1 or 2, X is a bridging group between two gallium atoms, y is an integer selected from the group consisting 1 and 2, z is an integer of at least 2, each Y is a ligand selected from the group consisting of aryl, alkyl, hydride and halide with the proviso that at least one Y is a ligand selected from the group consisting of aryl, alkyl and halide.

A multi-frequency EPR and ENDOR study of Rh and Ir complexes in alkali and silver halides

NASA Astrophysics Data System (ADS)

Callens, F.; Vrielinck, H.; Matthys, P.

2003-01-01

Aliovalent Rh and Ir cations have been frequently used to influence the photographic properties of silver halide emulsions. The doping introduces several types of related defects with distinct trapping and recombination properties. EPR and ENDOR are, in principle, ideally suited for the determination of the microscopic structure of the individual centres but it will be demonstrated that well-chosen, sometimes sophisticated multi-frequency experiments are necessary in order to (partially) reach this goal. Model studies on single crystals of AgCl and NaCl also appeared indispensable for the unravelling of the spectra. In the review of Rh-centres in NaCl and AgCl special attention is paid to methods that allow to detect cation vacancies near Rh2+ complexes. An alternative explanation for the high temperature behaviour of the [RhCl6](4-) complexes in AgCl is presented.

Application of SERS spectroscopy to the identification of (3,4-methylenedioxy)amphetamine in forensic samples utilizing matrix stabilized silver halides.

PubMed

Sägmüller, B; Schwarze, B; Brehm, G; Schneider, S

2001-11-01

A method based on surface-enhanced Raman scattering (SERS) spectroscopy was developed to meet the need for the reliable and rapid identification of illicit drugs such as the 'designer drug' XTC, preferably to increase the security of legal certificates. A matrix stabilized silver halide dispersion on a microtiter plate is used as the SERS-active substrate, providing an easy to use system for sample preparation and probing by means of a Raman microscope. The potential of the method is demonstrated by applying it to the identification of the psychoactive ingredients of drug containing tablets which were confiscated by the local police at techno-music events. The samples of interest were 26 different brands of XTC tablets and several pieces of evidence (powders) containing amphetamine. For reference, we show SERS and Raman spectra of pristine amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethamphetamine.

Analysis of higher order harmonics with holographic reflection gratings

NASA Astrophysics Data System (ADS)

Mas-Abellan, P.; Madrigal, R.; Fimia, A.

2017-05-01

Silver halide emulsions have been considered one of the most energetic sensitive materials for holographic applications. Nonlinear recording effects on holographic reflection gratings recorded on silver halide emulsions have been studied by different authors obtaining excellent experimental results. In this communication specifically we focused our investigation on the effects of refractive index modulation, trying to get high levels of overmodulation that will produce high order harmonics. We studied the influence of the overmodulation and its effects on the transmission spectra for a wide exposure range by use of 9 μm thickness films of ultrafine grain emulsion BB640, exposed to single collimated beams using a red He-Ne laser (wavelength 632.8 nm) with Denisyuk configuration obtaining a spatial frequency of 4990 l/mm recorded on the emulsion. The experimental results show that high overmodulation levels of refractive index produce second order harmonics with high diffraction efficiency (higher than 75%) and a narrow grating bandwidth (12.5 nm). Results also show that overmodulation produce diffraction spectra deformation of the second order harmonic, transforming the spectrum from sinusoidal to approximation of square shape due to very high overmodulation. Increasing the levels of overmodulation of refractive index, we have obtained higher order harmonics, obtaining third order harmonic with diffraction efficiency (up to 23%) and narrowing grating bandwidth (5 nm). This study is the first step to develop a new easy technique to obtain narrow spectral filters based on the use of high index modulation reflection gratings.

Use of radiation in preparative chemistry

NASA Technical Reports Server (NTRS)

Philipp, W. H.; Marksik, S. J.; May, C. E.; Lad, R. A.

1971-01-01

A summary and updating of previous work on the use of radiation chemistry for the preparation of pure materials are presented. Work was chiefly concerned with the reduction of metal salts in solution to the free metal using 2 MeV electrons. Metals deposited from aqueous solution are copper, silver, zinc, cadmium, thallium, tin, lead, antimony, iron, nickel, cobalt, and palladium. Dry organic solvents were evaluated for the deposition of metals based on a study involving deposition of antimony from soltions of antimony (III) chloride. The use of organic liquids for the preparation of anhydrous metal halides is also presented. Reaction mechanisms for both organic liquids and aqueous system are discussed.

Experimental study of the acrylamide photopolymer with a pulsed laser

NASA Astrophysics Data System (ADS)

García, C.; Pascual, I.; Costela, A.; García-Moreno, I.; Fimia, A.; Sastre, R.

2001-02-01

We have demonstrated that holograms may be recorded in polyvinyl alcohol/acrylamide photopolymer dry films using pulsed laser exposure with a pulse length of 8 ns. We also studied the effect of the pulse fluency together with the number of pulses necessary to obtain maximum diffraction efficiency. The recording was performed using a holographic copying process. The original was a grating of 1000 lines/mm processed using silver halide sensitized gelatin. Diffraction efficiencies of 55% were obtained with sensitivities similar to those reached with the same material and cw exposure, without the need for pre-processing or final processing of the gratings.

Variations in anthropogenic silver in a large Patagonian lake correlate with global shifts in photographic processing technology.

PubMed

Juncos, Romina; Campbell, Linda; Arcagni, Marina; Daga, Romina; Rizzo, Andrea; Arribére, María; Ribeiro Guevara, Sergio

2017-04-01

At the beginning of the 21st century, digital imaging technology replaced the traditional silver-halide film photography which had implications in Ag contamination. Lake Nahuel Huapi is a popular Patagonia tourist destination impacted by municipal silver (Ag) contamination from photographic processing facilities since 1990's. Silver concentrations in a dated sediment core from the lake bottom showed a 10-fold increase above background levels in the second half of the 20th century, then a decrease. This trend corresponds well with published annual global photography industry demand for Ag, which clearly shows the evolution and replacement of the traditional silver-halide film photography by digital imaging technology. There were significant decreases in Ag concentrations in sediments, mussels and fish across the lake between 1998 and 2011. Lower trophic organisms had variable whole-body Ag concentrations, from 0.2-2.6 μg g -1 dry weight (DW) in plankton to 0.02-3.1 μg g -1 DW in benthic macroinvertebrates. Hepatic Ag concentrations in crayfish, mussels and predatory fish were significantly elevated relative to muscle which often have Ag concentrations below the detection limit (0.01-0.05 μg g -1 DW). Trophodynamic analyses using δ 15 N and whole-body invertebrate and muscle Ag concentrations indicated food web biodilution trends. High sedimentation rates in conjunction with the reduction of silver waste products discharged to the lake, as a result of the change to digital image processing technologies, are resulting in unplanned but welcome remediation of the Ag contamination in Lake Nahuel Huapi. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shallow halogen vacancies in halide optoelectronic materials

NASA Astrophysics Data System (ADS)

Shi, Hongliang; Du, Mao-Hua

2014-11-01

Halogen vacancies (VH ) are usually deep color centers (F centers) in halides and can act as major electron traps or recombination centers. The deep VH contributes to the typically poor carrier transport properties in halides. However, several halides have recently emerged as excellent optoelectronic materials, e.g., C H3N H3Pb I3 and TlBr. Both C H3N H3Pb I3 and TlBr have been found to have shallow VH , in contrast to commonly seen deep VH in halides. In this paper, several halide optoelectronic materials, i.e., C H3N H3Pb I3 , C H3N H3Sn I3 (photovoltaic materials), TlBr, and CsPbB r3 (gamma-ray detection materials) are studied to understand the material chemistry and structure that determine whether VH is a shallow or deep defect in a halide material. It is found that crystal structure and chemistry of n s2 ions both play important roles in creating shallow VH in halides such as C H3N H3Pb I3 , C H3N H3Sn I3 , and TlBr. The key to identifying halides with shallow VH is to find the right crystal structures and compounds that suppress cation orbital hybridization at VH , such as those with large cation-cation distances and low anion coordination numbers and those with crystal symmetry that prevents strong hybridization of cation dangling bond orbitals at VH . The results of this paper provide insight and guidance to identifying halides with shallow VH as good electronic and optoelectronic materials.

Shallow halogen vacancies in halide optoelectronic materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Hongliang; Du, Mao -Hua

2014-11-05

Halogen vacancies (V H) are usually deep color centers (F centers) in halides and can act as major electron traps or recombination centers. The deep V H contributes to the typically poor carrier transport properties in halides. However, several halides have recently emerged as excellent optoelectronic materials, e.g., CH 3NH 3PbI 3 and TlBr. Both CH 3NH 3PbI 3 and TlBr have been found to have shallow V H, in contrast to commonly seen deep V H in halides. In this paper, several halide optoelectronic materials, i.e., CH 3NH 3PbI 3, CH 3NH 3SnI 3 (photovoltaic materials), TlBr, and CsPbBrmore » 3, (gamma-ray detection materials) are studied to understand the material chemistry and structure that determine whether V H is a shallow or deep defect in a halide material. It is found that crystal structure and chemistry of ns 2 ions both play important roles in creating shallow V H in halides such as CH 3NH 3PbI 3, CH 3NH 3SnI 3, and TlBr. The key to identifying halides with shallow V H is to find the right crystal structures and compounds that suppress cation orbital hybridization at V H, such as those with long cation-cation distances and low anion coordination numbers, and those with crystal symmetry that prevents strong hybridization of cation dangling bond orbitals at V H. Furthermore, the results of this paper provide insight and guidance to identifying halides with shallow V H as good electronic and optoelectronic materials.« less

The Current Status of the Development of Light-Sensitive Media for Holography (a Review)

NASA Astrophysics Data System (ADS)

Barachevsky, V. A.

2018-03-01

The results of studies that have been performed over the last decade in the field of development of silver halide and nonsilver holographic recording media of organic and inorganic origin are analyzed. It is shown that previously developed materials mainly allow the development of holographic investigations. Among irreversible materials, considerable progress has been made in improving the characteristics of photopolymerizable recording media, which has allowed their use in color image holography and 3D optical archive-type memory, as well as for fabricating holographic optical elements. In the field of improving the properties of reversible holographic recording media, practically significant results have been obtained for the creation of photoanisotropic materials based on azo dyes experiencing cis-trans photoisomerization, which allow the recording of polarization holograms. The needs of dynamic holography have been satisfied by lightsensitive doped inorganic crystals and polymer layers that have been created with nonlinear optical properties.

Spectral staining of tumor tissue by fiber optic FTIR spectroscopy

NASA Astrophysics Data System (ADS)

Salzer, Reiner; Steiner, Gerald; Kano, Angelique; Richter, Tom; Bergmann, Ralf; Rodig, Heike; Johannsen, Bernd; Kobelke, Jens

2003-07-01

Infrared (IR) optical fiber have aroused great interest in recent years because of their potential in in-vivo spectroscopy. This potential includes the ability to be flexible, small and to guide IR light in a very large range of wavelengths. Two types - silver halide and chalcogenide - infrared transmitting fibers are investigated in the detection of a malignant tumor. As a test sample for all types of fibers we used a thin section of an entire rat brain with glioblastoma. The fibers were connected with a common infrared microscope. Maps across the whole tissue section with more than 200 spectra were recorded by moving the sample with an XY stage. Data evaluation was performed using fuzzy c-means cluster analysis (FCM). The silver halide fibers provided excellent results. The tumor was clearly discernible from healthy tissue. Chalcogenide fibers are not suitable to distinguish tumor from normal tissue because the fiber has a very low transmittance in the important fingerprint region.

Silver halide fiber optic radiometry for temperature monitoring and control of tissues heated by microwave

NASA Astrophysics Data System (ADS)

Shenfeld, Ofer; Belotserkovsky, Edward; Goldwasser, Benad; Zur, Albert; Katzir, Abraham

1993-02-01

The heating of tissue by microwave radiation has attained a place of importance in various medical fields, such as the treatment of malignancies, urinary retention, and hypothermia. Accurate temperature measurements in these treated tissues is important for treatment planning and for the control of the heating process. It is also important to be able to measure spacial temperature distribution in the tissues because they are heated in a nonuniform way by the microwave radiation. Conventional temperature sensors used today are inaccurate in the presence of microwave radiation and require contact with the heated tissue. Fiber optic radiometry makes it possible to measure temperatures accurately in the presence of microwave radiation and does not require contact with the tissue. Accurate temperature measurements of tissues heated by microwave was obtained using a silver halide optic radiometer, enabling control of the heating process in other regions of the tissue samples. Temperature mappings of the heated tissues were performed and the nonuniform temperature distributions in these tissues was demonstrated.

Mesoporous Colloidal Superparticles of Platinum-Group Nanocrystals with Surfactant-Free Surfaces and Enhanced Heterogeneous Catalysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hu, Yongxing; Liu, Yuzi; Sun, Yugang

2015-01-23

Synthesis of colloidal superparticles (CSPs) of nanocrystals, a class of assembled nanocrystals in the form of colloidal particles, has been emerging as a new frontier in the field of nanotechnology because of their potential novel properties originated from coupling of individual nanocrystals in CSPs. Here, a facile approach is reported for the controlled synthesis of mesoporous CSPs made of various platinum-group nanocrystals that exhibit high colloidal stability and ligand-free surfaces to significantly benefit their applications in solution-phase heterogeneous catalysis. The synthesis relies on self-limiting growth of composite particles through coprecipitation of both Pt-group nanocrystals (or their precursor compounds) and silvermore » halides on sacrificial substrates of colloidal silver particles. The intermediate silver halides in the composite particles play the critical role in limiting the continuous growth (and/or coalescence) of individual Pt-group nanocrystals and they can be selectively dissolved to create nanoscale pores in the resulting CSPs.« less

Structure modeling and manufacturing PCFs for the range of 2-25 μm

NASA Astrophysics Data System (ADS)

Lvov, Alexandr; Salimgareev, Dmitrii; Korsakov, Michail; Korsakov, Alexandr; Zhukova, Liya

2017-11-01

Photostable and flexible materials transparent at the wide spectral range are necessary for the development of optical fiber units. Solid solutions of silver and monadic thallium halides are the most suitable crystal media for this purpose. The goal of our research was the search of optimum structure for the fibers with a single mode operation and a rather large core diameter. We modelled fiber structures (solid-core, hollow-core, active-core PCF) with various ratio of inserts diameters and increments between the inserts, basing on two crystal systems: AgCl-AgBr and AgBr-TlI. Then we chose the single mode fiber structure and manufactured it by means of extrusion.

Method for recovering hydrocarbons from molten metal halides

DOEpatents

Pell, Melvyn B.

1979-01-01

In a process for hydrocracking heavy carbonaceous materials by contacting such carbonaceous materials with hydrogen in the presence of a molten metal halide catalyst to produce hydrocarbons having lower molecular weights and thereafter recovering the hydrocarbons so produced from the molten metal halide, an improvement comprising injecting into the spent molten metal halide, a liquid low-boiling hydrocarbon stream is disclosed.

Archival Stability of Microfilm.

ERIC Educational Resources Information Center

Materazzi, Albert R.

This report is in response to complaints and criticism by the library community on the Superintendent of Documents' decision to furnish third generation diazo microfiche for the Depository Library program. It reviews some of the basic photographic chemistry of both silver halides and diazos which have an influence on dark stability. A review of…

Archival Stability of Microfilm--A Technical Review.

ERIC Educational Resources Information Center

Materazzi, Albert R.

The purpose of this report is to acquaint all personnel with some technical aspects of micrographics. The various film types used in the production of microfiche are discussed, including silver halide, diazo, and vesicular films. Other imaging systems used in micrographics are reviewed, and a basic introduction to sensitometry is given. The…

Microfilm--Which Film Type, Which Application?

ERIC Educational Resources Information Center

Dodson, Suzanne Cates

1985-01-01

Report on characteristics of different kinds of microfilm available indicates proper film for specific needs. Silver halide and nonsilver films, diazo film, vesicular film, reaction of films to light, effect of heat and humidity on films, film susceptibility to scratching, and potential longevity of film types are covered. (35 references) (EJS)

Spaulding and Materazzi Revisited: A Ten Year Retrospect.

ERIC Educational Resources Information Center

Bourke, Thomas A.

1988-01-01

Summarizes the ANSI standards for archival film and looks at the debate surrounding questions of archival storage, durability in a working environment, and affordability among proponents of silver halide, diazo, and vesicular films. Articles written by Carl Spaulding and Albert R. Materazzi on the subject are reviewed. (11 references) (MES)

A novel method for fabrication of continuous-relief optical elements

NASA Astrophysics Data System (ADS)

Guo, Xiaowei; Du, Jinglei; Chen, Mingyong; Ma, Yanqin; Zhu, Jianhua; Peng, Qinjun; Guo, Yongkang; Du, Chunlei

2005-08-01

A novel method for the fabrication of continuous micro-optical components is presented in this paper. It employs a computer controlled spatial-light-modulator (SLM) as a switchable projection mask and silver-halide sensitized gelatin (SHSG) as recording material. By etching SHSG with enzyme solution, the micro-optical components with relief modulation can be generated through special processing procedures. The principles of digital SLM-based lithography and enzyme etching SHSG are discussed in detail, and microlens arrays, micro axicon-lens arrays and gratings with good profile were achieved. This method is simple, cheap and the aberration in processing procedures can be in-situ corrected in the step of designing mask, so it is a practical method to fabricate continuous profile for low-volume production.

Galvanic Cells and the Determination of Equilibrium Constants

ERIC Educational Resources Information Center

Brosmer, Jonathan L.; Peters, Dennis G.

2012-01-01

Readily assembled mini-galvanic cells can be employed to compare their observed voltages with those predicted from the Nernst equation and to determine solubility products for silver halides and overall formation constants for metal-ammonia complexes. Results obtained by students in both an honors-level first-year course in general chemistry and…

Phase holograms in silver halide emulsions without a bleaching step

NASA Astrophysics Data System (ADS)

Belendez, Augusto; Madrigal, Roque F.; Pascual, Inmaculada V.; Fimia, Antonio

2000-03-01

Phase holograms in holographic emulsions are usually obtained by two bath processes (developing and bleaching). In this work we present a one step method to reach phase holograms with silver-halide emulsions. Which is based on the variation of the conditions of the typical developing processes of amplitude holograms. For this, we have used the well-known chemical developer, AAC, which is composed by ascorbic acid as a developing agent and sodium carbonate anhydrous as accelerator. Agfa 8E75 HD and BB-640 plates were used to obtain these phase gratings, whose colors are between yellow and brown. In function of the parameters of this developing method the resulting diffraction efficiency and optical density of the diffraction gratings were studied. One of these parameters studied is the influence of the grain size. In the case of Agfa plates diffraction efficiency around 18% with density < 1 has been reached, whilst with the BB-640 emulsion, whose grain is smaller than that of the Agfa, diffraction efficiency near 30% has been obtained. The resulting gratings were analyzed through X-ray spectroscopy showing the differences of the structure of the developed silver when amplitude and transmission gratings are obtained. The angular response of both (transmission and amplitude) gratings were studied, where minimal transmission is showed at the Braggs angle in phase holograms, whilst a maximal value is obtained in amplitude gratings.

Luminescent zero-dimensional organic metal halide hybrids with near-unity quantum efficiency.

PubMed

Zhou, Chenkun; Lin, Haoran; Tian, Yu; Yuan, Zhao; Clark, Ronald; Chen, Banghao; van de Burgt, Lambertus J; Wang, Jamie C; Zhou, Yan; Hanson, Kenneth; Meisner, Quinton J; Neu, Jennifer; Besara, Tiglet; Siegrist, Theo; Lambers, Eric; Djurovich, Peter; Ma, Biwu

2018-01-21

Single crystalline zero-dimensional (0D) organic-inorganic hybrid materials with perfect host-guest structures have been developed as a new generation of highly efficient light emitters. Here we report a series of lead-free organic metal halide hybrids with a 0D structure, (C 4 N 2 H 14 X) 4 SnX 6 (X = Br, I) and (C 9 NH 20 ) 2 SbX 5 (X = Cl), in which the individual metal halide octahedra (SnX 6 4- ) and quadrangular pyramids (SbX 5 2- ) are completely isolated from each other and surrounded by the organic ligands C 4 N 2 H 14 X + and C 9 NH 20 + , respectively. The isolation of the photoactive metal halide species by the wide band gap organic ligands leads to no interaction or electronic band formation between the metal halide species, allowing the bulk materials to exhibit the intrinsic properties of the individual metal halide species. These 0D organic metal halide hybrids can also be considered as perfect host-guest systems, with the metal halide species periodically doped in the wide band gap matrix. Highly luminescent, strongly Stokes shifted broadband emissions with photoluminescence quantum efficiencies (PLQEs) of close to unity were realized, as a result of excited state structural reorganization of the individual metal halide species. Our discovery of highly luminescent single crystalline 0D organic-inorganic hybrid materials as perfect host-guest systems opens up a new paradigm in functional materials design.

Effects of the surface modification of silver nanoparticles on the surface-enhanced Raman spectroscopy of methylene blue for borohydride-reduced silver colloid

NASA Astrophysics Data System (ADS)

Dong, Xiao; Gu, Huaimin; Kang, Jian; Yuan, Xiaojuan; Wu, Jiwei

2010-12-01

The paper further investigated the relationship between the modification of the surface chemistry and the enhancement mechanisms of borohydride-reduced silver particles (BRSC). The bands of residual ions die down while the anomalous bands increase gradually with the increasing of the concentration of Cl - and Br -. It means the residual ions are displaced gradually by the added Cl - or Br - and the two halides can lead to the aggregation of the BRSC to a certain extent. However, the most strongly binding anions - I -, cannot cause any aggregation of silver particles. From the detection of methylene blue (MB), the relationship between the modification of silver surface chemistry and the enhancement mechanisms was discussed. Chloride gives the greatest enhancement while the iodide gives the lowest enhancement among the different kinds of anions. There are also some anomalous bands in the SERS spectra of MB, and these anomalous bands were given rational explanation in this paper.

Method for producing hydrocarbon fuels from heavy polynuclear hydrocarbons by use of molten metal halide catalyst

DOEpatents

Gorin, Everett

1979-01-01

In a process for hydrocracking heavy polynuclear carbonaceous feedstocks to produce lighter hydrocarbon fuels by contacting the heavy feedstocks with hydrogen in the presence of a molten metal halide catalyst, thereafter separating at least a substantial portion of the carbonaceous material associated with the reaction mixture from the spent molten metal halide and thereafter regenerating the metal halide catalyst, an improvement comprising contacting the spent molten metal halide catalyst after removal of a major portion of the carbonaceous material therefrom with an additional quantity of hydrogen is disclosed.

DIMENSION STABILIZED FIXED PHOTOGRAPHIC TYPE EMULSION AND A METHOD FOR PRODUCING SAME

DOEpatents

Gilbert, F.C.

1962-03-13

A process is given for stabilizing the dimensions of fixed gelatin-base photographic type emulsions containing silver halide, and particularly to such emulsions containing large amounts of silver chloride for use as nuclear track emulsions, so that the dimensions of the final product are the same as or in a predetermined fixed ratio to the dimensions of the emulsions prior to exposure. The process comprises contacting an exposed, fixed emulsion with a solution of wood rosin dissolved in ethyl alcohol for times corresponding to the dimensions desired, and thereafter permitting the alcohol to evaporate. (AEC)

Holographic Moire Contouring

NASA Astrophysics Data System (ADS)

Sciammarella, C. A.; Sainov, Ventseslav; Simova, Eli

1990-04-01

Theoretical analysis and experimental results on holographic moire contouring (HMC) of difussely reflecting objects are presented. The sensitivity and application constraints of the method are discussed. A high signal-to-noise ratio and contrast of the fringes is achieved through the use of high quality silver halide holographic plates HP-650. A good agreement between theoretical and experimental results is observed.

36 CFR 1254.108 - What are NARA's requirements for the microfilming process?

Code of Federal Regulations, 2014 CFR

2014-07-01

... responsibility for loss or damage to microfilm equipment or supplies you leave unattended. (j) We inspect the... refilm the records. (k) When you film 10,000 or fewer images, you must provide NARA with a silver halide duplicate negative upon completion of the project. When the project involves more than 10,000 images, you...

36 CFR 1254.108 - What are NARA's requirements for the microfilming process?

Code of Federal Regulations, 2010 CFR

2010-07-01

... responsibility for loss or damage to microfilm equipment or supplies you leave unattended. (j) We inspect the... refilm the records. (k) When you film 10,000 or fewer images, you must provide NARA with a silver halide duplicate negative upon completion of the project. When the project involves more than 10,000 images, you...

36 CFR 1254.108 - What are NARA's requirements for the microfilming process?

Code of Federal Regulations, 2012 CFR

2012-07-01

... responsibility for loss or damage to microfilm equipment or supplies you leave unattended. (j) We inspect the... refilm the records. (k) When you film 10,000 or fewer images, you must provide NARA with a silver halide duplicate negative upon completion of the project. When the project involves more than 10,000 images, you...

36 CFR 1254.108 - What are NARA's requirements for the microfilming process?

Code of Federal Regulations, 2011 CFR

2011-07-01

... responsibility for loss or damage to microfilm equipment or supplies you leave unattended. (j) We inspect the... refilm the records. (k) When you film 10,000 or fewer images, you must provide NARA with a silver halide duplicate negative upon completion of the project. When the project involves more than 10,000 images, you...

Low spatial frequency characterization of holographic recording materials applied to correlation

NASA Astrophysics Data System (ADS)

Márquez, A.; Neipp, C.; Beléndez, A.; Campos, J.; Pascual, I.; Yzuel, M. J.; Fimia, A.

2003-09-01

Accurate recording of computer-generated holograms (CGH) on a phase material is not a trivial task. The range of available phase materials is large, and their suitability depends on the fabrication technique chosen to produce the hologram. We are particularly interested in low-cost fabrication techniques, easily available for any lab. In this work we present the results obtained with a wide variety of phase holographic recording materials, characterized at low spatial frequencies (leq32 lp mm-1) which is the range associated with the technique we use to produce the CGHs. We have considered bleached emulsion, silver halide sensitized gelatin (SHSG) and dichromated gelatin. Some interesting differences arise between the behaviour of these materials in the usual holographic range (>1000 lp mm-1), and the low-frequency range intended for digital holography. The ultimate goal of this paper is to establish the suitability of different phase materials as the media to generate correlation filters for optical pattern recognition. In all the materials considered, the phase filters generated ensure the discrimination of the target in the recognition process. Taking into account all the experimental results, we can say that SHSG is the best material to generate phase CGHs with low spatial frequencies.

Unraveling luminescence mechanisms in zero-dimensional halide perovskites

DOE PAGES

Han, Dan; Shi, Hongliang; Ming, Wenmei; ...

2018-01-01

Zero-dimensional (0D) halides perovskites, in which anionic metal-halide octahedra (MX 6 ) 4− are separated by organic or inorganic countercations, have recently shown promise as excellent luminescent materials.

Unraveling luminescence mechanisms in zero-dimensional halide perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Dan; Shi, Hongliang; Ming, Wenmei

Zero-dimensional (0D) halides perovskites, in which anionic metal-halide octahedra (MX 6 ) 4− are separated by organic or inorganic countercations, have recently shown promise as excellent luminescent materials.

Thallous halide materials for use in cryogenic applications

NASA Technical Reports Server (NTRS)

Lawless, William N. (Inventor)

1981-01-01

Thallous halides, either alone or in combination with other ceramic materials, are used in cryogenic applications such as heat exchange material for the regenerator section of a closed-cycle cryogenic refrigeration section, as stabilizing coatings for superconducting wires, and as dielectric insulating materials. The thallous halides possess unusually large specific heats at low temperatures, have large thermal conductivities, are nonmagnetic, and are nonconductors of electricity. They can be formed into a variety of shapes such as spheres, bars, rods, or the like and can be coated onto substrates.

Calixarene-based potentiometric ion-selective electrodes for silver.

PubMed

O'Connor, K M; Svehla, G; Harris, S J; McKervey, M A

1992-11-01

Four lipophilic sulphur and/or nitrogen containing calixarene derivatives have been tested as ionophores in Ag(I)-selective poly (vinyl chloride) membrane electrodes. All gave acceptable linear responses with one giving a response of 50 mV/dec in the Ag(I) ion activity range 10(-4)-10(-1)M and high selectivity towards other transition metals and sodium and potassium ions. This ionophore was also tested as a membrane coated glassy-carbon electrode where the sensitivity and selectivity of the conventional membrane electrode was found to be repeated. The latter electrode was then used in potentiometric titrations of halide ions with silver nitrate.

Unraveling luminescence mechanisms in zero-dimensional halide perovskites

DOE PAGES

Han, Dan; Shi, Hongliang; Ming, Wenmei; ...

2018-05-18

Here, zero-dimensional (0D) halides perovskites, in which anionic metal-halide octahedra (MX 6) 4– are separated by organic or inorganic countercations, have recently shown promise as excellent luminescent materials.

A transportable system for the in situ recording of color Denisyuk holograms of Greek cultural heritage artifacts in silver halide panchromatic emulsions and an optimized illuminating device for the finished holograms

NASA Astrophysics Data System (ADS)

Sarakinos, A.; Lembessis, A.; Zervos, N.

2013-02-01

In this paper we will present the Z-Lab transportable color holography system, the HoLoFoS illuminator and results of actual in situ recording of color Denisyuk holograms of artifacts on panchromatic silver halide emulsions. Z-lab and HoLoFoS were developed to meet identified prerequisites of holographic recording of artifacts: a) in situ recording b) a high degree of detail and color reproduction c) a low degree of image distortions. The Z-Lab consists of the Z3RGB camera, its accessories and a mobile darkroom. HoLoFoS is an RGB LED-based lighting device for the display of color holograms. The device is capable of digitally controlled intensity mixing and provides a beam of uniform color cross section. The small footprint and emission characteristics of the device LEDs result in a narrow band, quasi point source at selected wavelengths. A case study in recording and displaying 'Optical Clones' of Greek cultural heritage artifacts with the aforementioned systems will also be presented.

Coulometric thermometric titration of halides in molten calcium nitrate tetrahydrate.

PubMed

Zsigrai, I J; Bartusz, D B

1983-01-01

A method for coulometric thermometric precipitation titrations of chloride, bromide and iodide in molten calcium nitrate tetrahydrate at 55 degrees with coulometrically generated silver ions has been developed. The change in temperature during the titration is followed with the aid of a thermistor bridge coupled to a recorder. To minimize the temperature effect of the passage of current through the melt, two thermistors are connected in opposition in the bridge, with one in the anodic and the other in the cathodic cell compartment. Amounts of 62-80 mumole of halide have been determined with relative error below 0.4% and relative standard deviation less than 2.7%. The relative error in determination of 40 mumole of iodide was + 2%.

Film Recording of Digital Color Images

DTIC Science & Technology

1975-05-28

equipped with ted, .reen and bloe filters, the proiected Uaqes of the three slides were overlayed in exact register. The ooality of the resultlno...black and white (monochrome) photographic emulsion is prepared by suspending a mixture of silver halides and sensitizing agents in gelatin, coating the...waveleugth, changes take place which renJer the grain more susceptible to chemical reduction by a developing agent . These invisible changes in the

A History of the Chemical Innovations in Silver-Halide Materials for Color PhotographyIII. Dye Tranfer Process — Instant Color Photography

NASA Astrophysics Data System (ADS)

Oishi, Yasushi

A historical review of the technological developments of instant color photographic process, is presented with emphasis on the innovation processes at the following main turning points: 1) the creation of instant photography by E. H. Land in 1948 (one step processing by transfer of image-forming materials), 2) the advent of instant color photography based on dye developer, by Polaroid Corp., in 1963 (departing from dye-forming development, forming a direct positive preformed-dye image with a negative emulsion, but constraining the sensitive-material designs), 3) the introduction of a color instant product containing redox dye releaser with improved auto-positive emulsion, by Eastman Kodak Co., in 1976 (producing much improved color image quality, freed from the design constraints), and 4) the realization of absolute one-step photography by the integral film- unit system, by Polaroid in 1972. And the patent litigation (1976-86) raised by Polaroid against Kodak allegedly infringing on the integral film-unit patents caused the vast impacts on the industry.

Self-Organized Superlattice and Phase Coexistence inside Thin Film Organometal Halide Perovskite.

PubMed

Kim, Tae Woong; Uchida, Satoshi; Matsushita, Tomonori; Cojocaru, Ludmila; Jono, Ryota; Kimura, Kohei; Matsubara, Daiki; Shirai, Manabu; Ito, Katsuji; Matsumoto, Hiroaki; Kondo, Takashi; Segawa, Hiroshi

2018-02-01

Organometal halide perovskites have attracted widespread attention as the most favorable prospective material for photovoltaic technology because of their high photoinduced charge separation and carrier transport performance. However, the microstructural aspects within the organometal halide perovskite are still unknown, even though it belongs to a crystal system. Here direct observation of the microstructure of the thin film organometal halide perovskite using transmission electron microscopy is reported. Unlike previous reports claiming each phase of the organometal halide perovskite solely exists at a given temperature range, it is identified that the tetragonal and cubic phases coexist at room temperature, and it is confirmed that superlattices composed of a mixture of tetragonal and cubic phases are self-organized without a compositional change. The organometal halide perovskite self-adjusts the configuration of phases and automatically organizes a buffer layer at boundaries by introducing a superlattice. This report shows the fundamental crystallographic information for the organometal halide perovskite and demonstrates new possibilities as promising materials for various applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The Electrical and Optical Properties of Organometal Halide Perovskites Relevant to Optoelectronic Performance.

PubMed

Adinolfi, Valerio; Peng, Wei; Walters, Grant; Bakr, Osman M; Sargent, Edward H

2018-01-01

Organometal halide perovskites are under intense study for use in optoelectronics. Methylammonium and formamidinium lead iodide show impressive performance as photovoltaic materials; a premise that has spurred investigations into light-emitting devices and photodetectors. Herein, the optical and electrical material properties of organometal halide perovskites are reviewed. An overview is given on how the material composition and morphology are tied to these properties, and how these properties ultimately affect device performance. Material attributes and techniques used to estimate them are analyzed for different perovskite materials, with a particular focus on the bandgap, mobility, diffusion length, carrier lifetime, and trap-state density. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Rapid dehalogenation of pesticides and organics at the interface of reduced graphene oxide-silver nanocomposite.

PubMed

Koushik, Dibyashree; Sen Gupta, Soujit; Maliyekkal, Shihabudheen M; Pradeep, T

2016-05-05

This paper reports dehalogenation of various organohalides, especially aliphatic halocarbons and pesticides at reduced graphene oxide-silver nanocomposite (RGO@Ag). Several pesticides as well as chlorinated and fluorinated alkyl halides were chosen for this purpose. The composite and the products of degradation were characterized thoroughly by means of various microscopic and spectroscopic techniques. A sequential two-step mechanism involving dehalogenation of the target pollutants by silver nanoparticles followed by adsorption of the degraded compounds onto RGO was revealed. The composite showed unusual adsorption capacity, as high as 1534 mg/g, which facilitated the complete removal of the pollutants. Irrespective of the pollutants tested, a pseudo-second-order rate equation best described the adsorption kinetics. The affinity of the composite manifested chemical differences. The high adsorption capacity and re-usability makes the composite an excellent substrate for purification of water. Copyright © 2016 Elsevier B.V. All rights reserved.

Cation-Dependent Light-Induced Halide Demixing in Hybrid Organic–Inorganic Perovskites

DOE PAGES

Sutter-Fella, Carolin M.; Ngo, Quynh P.; Cefarin, Nicola; ...

2018-04-30

Mixed cation metal halide perovskites with increased power conversion efficiency, negligible hysteresis, and improved long-term stability under illumination, moisture, and thermal stressing have emerged as promising compounds for photovoltaic and optoelectronic applications. In this paper, we shed light on photoinduced halide demixing using in situ photoluminescence spectroscopy and in situ synchrotron X-ray diffraction (XRD) to directly compare the evolution of composition and phase changes in CH(NH 2) 2CsPb-halide (FACsPb-) and CH 3NH 3Pb-halide (MAPb-) perovskites upon illumination, thereby providing insights into why FACs-perovskites are less prone to halide demixing than MA-perovskites. We find that halide demixing occurs in both materials.more » However, the I-rich domains formed during demixing accumulate strain in FACsPb-perovskites but readily relax in MA-perovskites. The accumulated strain energy is expected to act as a stabilizing force against halide demixing and may explain the higher Br composition threshold for demixing to occur in FACsPb-halides. In addition, we find that while halide demixing leads to a quenching of the high-energy photoluminescence emission from MA-perovskites, the emission is enhanced from FACs-perovskites. This behavior points to a reduction of nonradiative recombination centers in FACs-perovskites arising from the demixing process and buildup of strain. FACsPb-halide perovskites exhibit excellent intrinsic material properties with photoluminescence quantum yields that are comparable to MA-perovskites. Finally, because improved stability is achieved without sacrificing electronic properties, these compositions are better candidates for photovoltaic applications, especially as wide bandgap absorbers in tandem cells.« less

Cation-Dependent Light-Induced Halide Demixing in Hybrid Organic-Inorganic Perovskites.

PubMed

Sutter-Fella, Carolin M; Ngo, Quynh P; Cefarin, Nicola; Gardner, Kira L; Tamura, Nobumichi; Stan, Camelia V; Drisdell, Walter S; Javey, Ali; Toma, Francesca M; Sharp, Ian D

2018-06-13

Mixed cation metal halide perovskites with increased power conversion efficiency, negligible hysteresis, and improved long-term stability under illumination, moisture, and thermal stressing have emerged as promising compounds for photovoltaic and optoelectronic applications. Here, we shed light on photoinduced halide demixing using in situ photoluminescence spectroscopy and in situ synchrotron X-ray diffraction (XRD) to directly compare the evolution of composition and phase changes in CH(NH 2 ) 2 CsPb-halide (FACsPb-) and CH 3 NH 3 Pb-halide (MAPb-) perovskites upon illumination, thereby providing insights into why FACs-perovskites are less prone to halide demixing than MA-perovskites. We find that halide demixing occurs in both materials. However, the I-rich domains formed during demixing accumulate strain in FACsPb-perovskites but readily relax in MA-perovskites. The accumulated strain energy is expected to act as a stabilizing force against halide demixing and may explain the higher Br composition threshold for demixing to occur in FACsPb-halides. In addition, we find that while halide demixing leads to a quenching of the high-energy photoluminescence emission from MA-perovskites, the emission is enhanced from FACs-perovskites. This behavior points to a reduction of nonradiative recombination centers in FACs-perovskites arising from the demixing process and buildup of strain. FACsPb-halide perovskites exhibit excellent intrinsic material properties with photoluminescence quantum yields that are comparable to MA-perovskites. Because improved stability is achieved without sacrificing electronic properties, these compositions are better candidates for photovoltaic applications, especially as wide bandgap absorbers in tandem cells.

Cation-Dependent Light-Induced Halide Demixing in Hybrid Organic–Inorganic Perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutter-Fella, Carolin M.; Ngo, Quynh P.; Cefarin, Nicola

Mixed cation metal halide perovskites with increased power conversion efficiency, negligible hysteresis, and improved long-term stability under illumination, moisture, and thermal stressing have emerged as promising compounds for photovoltaic and optoelectronic applications. In this paper, we shed light on photoinduced halide demixing using in situ photoluminescence spectroscopy and in situ synchrotron X-ray diffraction (XRD) to directly compare the evolution of composition and phase changes in CH(NH 2) 2CsPb-halide (FACsPb-) and CH 3NH 3Pb-halide (MAPb-) perovskites upon illumination, thereby providing insights into why FACs-perovskites are less prone to halide demixing than MA-perovskites. We find that halide demixing occurs in both materials.more » However, the I-rich domains formed during demixing accumulate strain in FACsPb-perovskites but readily relax in MA-perovskites. The accumulated strain energy is expected to act as a stabilizing force against halide demixing and may explain the higher Br composition threshold for demixing to occur in FACsPb-halides. In addition, we find that while halide demixing leads to a quenching of the high-energy photoluminescence emission from MA-perovskites, the emission is enhanced from FACs-perovskites. This behavior points to a reduction of nonradiative recombination centers in FACs-perovskites arising from the demixing process and buildup of strain. FACsPb-halide perovskites exhibit excellent intrinsic material properties with photoluminescence quantum yields that are comparable to MA-perovskites. Finally, because improved stability is achieved without sacrificing electronic properties, these compositions are better candidates for photovoltaic applications, especially as wide bandgap absorbers in tandem cells.« less

Intermediate Temperature Fluids Life Tests - Theory

NASA Technical Reports Server (NTRS)

Tarau, Calin; Sarraf, David B.; Locci, Ivan E.; Anderson, William G.

2008-01-01

There are a number of different applications that could use heat pipes or loop heat pipes (LHPs) in the intermediate temperature range of 450 to 750 K, including space nuclear power system radiators, and high temperature electronics cooling. Potential working fluids include organic fluids, elements, and halides, with halides being the least understood, with only a few life tests conducted. Potential envelope materials for halide working fluids include pure aluminum, aluminum alloys, commercially pure (CP) titanium, titanium alloys, and corrosion resistant superalloys. Life tests were conducted with three halides (AlBr3, SbBr3, and TiCl4) and water in three different envelopes: two aluminum alloys (Al-5052, Al-6061) and Cp-2 titanium. The AlBr3 attacked the grain boundaries in the aluminum envelopes, and formed TiAl compounds in the titanium. The SbBr3 was incompatible with the only envelope material that it was tested with, Al-6061. TiCl4 and water were both compatible with CP2-titanium. A theoretical model was developed that uses electromotive force differences to predict the compatibility of halide working fluids with envelope materials. This theory predicts that iron, nickel, and molybdenum are good envelope materials, while aluminum and titanium halides are good working fluids. The model is in good agreement with results form previous life tests, as well as the current life tests.

a Study of the Effects of Processing Chemistry on the Holographic Image Space.

NASA Astrophysics Data System (ADS)

Kocher, Clive Joseph

Available from UMI in association with The British Library. Processing methods for reflection and transmission holograms were evaluated with a view to minimising distortion in the images of small, metallic, near field subjects, whilst retaining optimum quality. The study was limited to recordings made with the HeNe laser (633 nm) in conjunction with the Agfa Gevaert 8E75 HD silver halide emulsion on glass or film support (5^{' '} x 4^{' '} format). Simple ray diagrams were used to help predict angular distortion arising from emulsion shrinkage for a two-dimensional model. The main conclusions are: (a) Serious distortion of the order of several millimetres, and loss of resolution will occur in the images of reflection holograms unless careful attention is given to processing procedures. Evidence supports the hypothesis that shrinkage due to processing causes the fringe system to collapse with a resultant change in inclination angle, and hence a distortion of the reconstructed image. Minimum distortion occurs with a laser reconstructed hologram processed in a high tanning developer and rehalogenating bleach, none being detected under the test conditions. (b) The same problem was not apparent for the transmission hologram due to a different fringe orientation, and within the limitations of the measuring system, no distortion was detected for any processing system. Comparative tests were made to evaluate the differences in performance for the Agfa 8E75 HD emulsion on plate and film support. Results show a significant increase in speed for film (as high as times4) and shrinkage (~3%), under all processing conditions. The advantages of using Phenidone based developers are shown. The report also includes a comprehensive background theory section covering basic concepts, silver halide recording material, holographic processing chemistry, distortion in holograms and pulsed laser holography. A review of previous work on phase holograms is given. Although primarily intended for measurement, this report contains useful information of benefit to display holography.

Treatment of halogen-containing waste and other waste materials

DOEpatents

Forsberg, Charles W.; Beahm, Edward C.; Parker, George W.

1997-01-01

A process for treating a halogen-containing waste material. The process provides a bath of molten glass containing a sacrificial metal oxide capable of reacting with a halogen in the waste material. The sacrificial metal oxide is present in the molten glass in at least a stoichiometric amount with respect to the halogen in the waste material. The waste material is introduced into the bath of molten glass to cause a reaction between the halogen in the waste material and the sacrificial metal oxide to yield a metal halide. The metal halide is a gas at the temperature of the molten glass. The gaseous metal halide is separated from the molten glass and contacted with an aqueous scrubber solution of an alkali metal hydroxide to yield a metal hydroxide or metal oxide-containing precipitate and a soluble alkali metal halide. The precipitate is then separated from the aqueous scrubber solution. The molten glass containing the treated waste material is removed from the bath as a waste glass. The process of the invention can be used to treat all types of waste material including radioactive wastes. The process is particularly suited for separating halogens from halogen-containing wastes.

Treatment of halogen-containing waste and other waste materials

DOEpatents

Forsberg, C.W.; Beahm, E.C.; Parker, G.W.

1997-03-18

A process is described for treating a halogen-containing waste material. The process provides a bath of molten glass containing a sacrificial metal oxide capable of reacting with a halogen in the waste material. The sacrificial metal oxide is present in the molten glass in at least a stoichiometric amount with respect to the halogen in the waste material. The waste material is introduced into the bath of molten glass to cause a reaction between the halogen in the waste material and the sacrificial metal oxide to yield a metal halide. The metal halide is a gas at the temperature of the molten glass. The gaseous metal halide is separated from the molten glass and contacted with an aqueous scrubber solution of an alkali metal hydroxide to yield a metal hydroxide or metal oxide-containing precipitate and a soluble alkali metal halide. The precipitate is then separated from the aqueous scrubber solution. The molten glass containing the treated waste material is removed from the bath as a waste glass. The process of the invention can be used to treat all types of waste material including radioactive wastes. The process is particularly suited for separating halogens from halogen-containing wastes. 3 figs.

Peculiarities of the photochemical processing of relief-phase holograms registered in a thin layer of silver halide emulsion

NASA Astrophysics Data System (ADS)

Brui, E. B.; Galashkina, I. A.

1993-12-01

Peculiarities of the photo-chemical processing of the relief-phase holograms, registered in the layers of argentum-halogenide emulsion PE-2 with the thickness 1 micrometers , are presented in the paper. It was found that in the case of such thickness the tanning processing does not provide the improvement of the maximal relief depth in comparison with the non-tanning process.

Improving Air Force Imagery Reconnaissance Support to Ground Commanders.

DTIC Science & Technology

1983-06-03

reconnaissance support in Southeast Asia due to the long response times of film recovery and 26 processing capabilities and inadequate command and control...reconnaissance is an integral part of the C31 information explosion. Traditional silver halide film products, chemically processed and manually distributed are...being replaced with electronic near-real-time (NRT) imaging sensors. The term "imagery" now includes not only conventional film based products (black

Large area fabrication of plasmonic nanoparticle grating structure by conventional scanning electron microscope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sudheer,, E-mail: sudheer@rrcat.gov.in; Tiwari, P.; Rai, V. N.

Plasmonic nanoparticle grating (PNG) structure of different periods has been fabricated by electron beam lithography using silver halide based transmission electron microscope film as a substrate. Conventional scanning electron microscope is used as a fabrication tool for electron beam lithography. Optical microscope and energy dispersive spectroscopy (EDS) have been used for its morphological and elemental characterization. Optical characterization is performed by UV-Vis absorption spectroscopic technique.

Hard copies for digital medical images: an overview

NASA Astrophysics Data System (ADS)

Blume, Hartwig R.; Muka, Edward

1995-04-01

This paper is a condensed version of an invited overview on the technology of film hard-copies used in radiology. Because the overview was given to an essentially nonmedical audience, the reliance on film hard-copies in radiology is outlined in greater detail. The overview is concerned with laser image recorders generating monochrome prints on silver-halide films. The basic components of laser image recorders are sketched. The paper concentrates on the physical parameters - characteristic function, dynamic range, digitization resolution, modulation transfer function, and noise power spectrum - which define image quality and information transfer capability of the printed image. A preliminary approach is presented to compare the printed image quality with noise in the acquired image as well as with the noise of state-of- the-art cathode-ray-tube display systems. High-performance laser-image- recorder/silver-halide-film/light-box systems are well capable of reproducing acquired radiologic information. Most recently development was begun toward a display function standard for soft-copy display systems to facilitate similarity of image presentation between different soft-copy displays as well as between soft- and hard-copy displays. The standard display function is based on perceptional linearization. The standard is briefly reviewed to encourage the printer industry to adopt it, too.

Alkali Halide Microstructured Optical Fiber for X-Ray Detection

NASA Technical Reports Server (NTRS)

DeHaven, S. L.; Wincheski, R. A.; Albin, S.

2014-01-01

Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. The results and associated materials difference are discussed.

Tailoring Oxygen Sensitivity with Halide Substitution in Difluoroboron Dibenzoylmethane Polylactide Materials

PubMed Central

DeRosa, Christopher A.; Kerr, Caroline; Fan, Ziyi; Kolpaczynska, Milena; Mathew, Alexander S.; Evans, Ruffin E.; Zhang, Guoqing; Fraser, Cassandra L.

2015-01-01

The dual-emissive properties of solid-state difluoroboron β-diketonate-poly(lactic acid) (BF2bdkPLA) materials have been utilized for biological oxygen sensing. In this work, BF2dbm(X)PLA materials were synthesized, where X = H, F, Cl, Br, and I. The effects of changing the halide substituent and PLA polymer chain length on the optical properties in dilute CH2Cl2 solutions and solid-state polymer films were studied. These luminescent materials show fluorescence, phosphorescence, and lifetime tunability on the basis of molecular weight, as well as lifetime modulation via the halide substituent. Short BF2dbm(Br)PLA (6.0 kDa) and both short and long BF2dbm(I)PLA polymers (6.0 or 20.3 kDa) have fluorescence and intense phosphorescence ideal for ratiometric oxygen sensing. The lighter halide-dye polymers with hydrogen, fluorine, and chlorine substitution have longer phosphorescence lifetimes and can be utilized as ultrasensitive oxygen sensors. Photostability was also analyzed for the polymer films. PMID:26480236

Destabilized and catalyzed borohydride for reversible hydrogen storage

DOEpatents

Mohtadi, Rana F [Northville, MI; Zidan, Ragaiy [Aiken, SC; Gray, Joshua [Aiken, SC; Stowe, Ashley C [Knoxville, TN; Sivasubramanian, Premkumar [Aiken, SC

2012-02-28

A process of forming a hydrogen storage material, including the steps of: providing a borohydride material of the formula: M(BH.sub.4).sub.x where M is an alkali metal or an alkaline earth metal and 1.ltoreq.x.ltoreq.2; providing an alanate material of the formula: M.sub.1(AlH.sub.4).sub.x where M.sub.1 is an alkali metal or an alkaline earth metal and 1.ltoreq.x.ltoreq.2; providing a halide material of the formula: M.sub.2Hal.sub.x where M.sub.2 is an alkali metal, an alkaline earth metal or transition metal and Hal is a halide and 1.ltoreq.x.ltoreq.4; combining the borohydride, alanate and halide materials such that 5 to 50 molar percent from the borohydride material is present forming a reaction product material having a lower hydrogen release temperature than the alanate material.

Origin of Reversible Photoinduced Phase Separation in Hybrid Perovskites.

PubMed

Bischak, Connor G; Hetherington, Craig L; Wu, Hao; Aloni, Shaul; Ogletree, D Frank; Limmer, David T; Ginsberg, Naomi S

2017-02-08

The distinct physical properties of hybrid organic-inorganic materials can lead to unexpected nonequilibrium phenomena that are difficult to characterize due to the broad range of length and time scales involved. For instance, mixed halide hybrid perovskites are promising materials for optoelectronics, yet bulk measurements suggest the halides reversibly phase separate upon photoexcitation. By combining nanoscale imaging and multiscale modeling, we find that the nature of halide demixing in these materials is distinct from macroscopic phase separation. We propose that the localized strain induced by a single photoexcited charge interacting with the soft, ionic lattice is sufficient to promote halide phase separation and nucleate a light-stabilized, low-bandgap, ∼8 nm iodide-rich cluster. The limited extent of this polaron is essential to promote demixing because by contrast bulk strain would simply be relaxed. Photoinduced phase separation is therefore a consequence of the unique electromechanical properties of this hybrid class of materials. Exploiting photoinduced phase separation and other nonequilibrium phenomena in hybrid materials more generally could expand applications in sensing, switching, memory, and energy storage.

Performance analysis and material dependence of micro holographic optical elements as couplers for fiber optic communication

NASA Astrophysics Data System (ADS)

Ambadiyil, Sajan; Prasannan, G.; Sathyan, Jithesh; Ajith Kumar, P. T.

2005-01-01

Holographic Optical Elements (HOEs) are gaining much importance and finding newer and better applications in areas of optical fiber communication and optical information processing systems. In contrast to conventional HOEs, optical communication and information systems require smaller and efficient elements of desired characteristics and transfer functions. Such Micro Holographic Optical Elements (MHOEs) can either be an HOE, recorded with two narrow beams of laser light or a segment cut from a larger HOE (SHOEs), and recorded in the conventional manner. In this study, micro holographic couplers, having specific focusing and diffraction characteristics were recorded in different holographic recording media such as silver halide and dichromated gelatin. Wavelength response of the elements was tested at 633 nm and 442 nm. Variation in diffraction efficiency/coupling factor, and insertion loss of the elements were studied. The paper reports in detail about the above results and related design considerations.

Multilayer Transparent Top Electrode for Solution Processed Perovskite/Cu(In,Ga)(Se,S)2 Four Terminal Tandem Solar Cells.

PubMed

Yang, Yang Michael; Chen, Qi; Hsieh, Yao-Tsung; Song, Tze-Bin; Marco, Nicholas De; Zhou, Huanping; Yang, Yang

2015-07-28

Halide perovskites (PVSK) have attracted much attention in recent years due to their high potential as a next generation solar cell material. To further improve perovskites progress toward a state-of-the-art technology, it is desirable to create a tandem structure in which perovskite may be stacked with a current prevailing solar cell such as silicon (Si) or Cu(In,Ga)(Se,S)2 (CIGS). The transparent top electrode is one of the key components as well as challenges to realize such tandem structure. Herein, we develop a multilayer transparent top electrode for perovskite photovoltaic devices delivering an 11.5% efficiency in top illumination mode. The transparent electrode is based on a dielectric/metal/dielectric structure, featuring an ultrathin gold seeded silver layer. A four terminal tandem solar cell employing solution processed CIGS and perovskite cells is also demonstrated with over 15% efficiency.

Photographic Processing Interpretation Facility Wastewater Conceptual Treatment Design.

DTIC Science & Technology

1983-03-01

Total Chromium (Cr) - - - ɘ.05 - Copper (Cu) - - - ɘ.05 - Iron (Fe) - - - - - Manganese (Mn) - - - ɘ.03 - Mercury (Hg) - - - ɘ.004 - Potassium (K...8.3 - Silver (Ag) 2.2 7.0 17 0.15 2.2 Sodium (Na) - - - 8.2 - Zinc (Zn) - - - 0.12 - Biochemical Oxygen " Demand (BOD_) - - - 40 - Sulfate (SO...nonconventional pollutants include boron, dissolved sol i halides, iron, ammonia, nitrogen, phenols, sulfate and TOC. ,P,, 99 percent of the 11,000

Alkali halide microstructured optical fiber for X-ray detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeHaven, S. L., E-mail: stanton.l.dehaven@nasa.gov, E-mail: russel.a.wincheski@nasa.gov; Wincheski, R. A., E-mail: stanton.l.dehaven@nasa.gov, E-mail: russel.a.wincheski@nasa.gov; Albin, S., E-mail: salbin@nsu.edu

Microstructured optical fibers containing alkali halide scintillation materials of CsI(Na), CsI(Tl), and NaI(Tl) are presented. The scintillation materials are grown inside the microstructured fibers using a modified Bridgman-Stockbarger technique. The x-ray photon counts of these fibers, with and without an aluminum film coating are compared to the output of a collimated CdTe solid state detector over an energy range from 10 to 40 keV. The photon count results show significant variations in the fiber output based on the materials. The alkali halide fiber output can exceed that of the CdTe detector, dependent upon photon counter efficiency and fiber configuration. Themore » results and associated materials difference are discussed.« less

Two-Dimensional Materials for Halide Perovskite-Based Optoelectronic Devices.

PubMed

Chen, Shan; Shi, Gaoquan

2017-06-01

Halide perovskites have high light absorption coefficients, long charge carrier diffusion lengths, intense photoluminescence, and slow rates of non-radiative charge recombination. Thus, they are attractive photoactive materials for developing high-performance optoelectronic devices. These devices are also cheap and easy to be fabricated. To realize the optimal performances of halide perovskite-based optoelectronic devices (HPODs), perovskite photoactive layers should work effectively with other functional materials such as electrodes, interfacial layers and encapsulating films. Conventional two-dimensional (2D) materials are promising candidates for this purpose because of their unique structures and/or interesting optoelectronic properties. Here, we comprehensively summarize the recent advancements in the applications of conventional 2D materials for halide perovskite-based photodetectors, solar cells and light-emitting diodes. The examples of these 2D materials are graphene and its derivatives, mono- and few-layer transition metal dichalcogenides (TMDs), graphdiyne and metal nanosheets, etc. The research related to 2D nanostructured perovskites and 2D Ruddlesden-Popper perovskites as efficient and stable photoactive layers is also outlined. The syntheses, functions and working mechanisms of relevant 2D materials are introduced, and the challenges to achieving practical applications of HPODs using 2D materials are also discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lanthanide doped strontium-barium cesium halide scintillators

DOEpatents

Bizarri, Gregory; Bourret-Courchesne, Edith; Derenzo, Stephen E.; Borade, Ramesh B.; Gundiah, Gautam; Yan, Zewu; Hanrahan, Stephen M.; Chaudhry, Anurag; Canning, Andrew

2015-06-09

The present invention provides for a composition comprising an inorganic scintillator comprising an optionally lanthanide-doped strontium-barium, optionally cesium, halide, useful for detecting nuclear material.

Characterization of cinematographic films by Laser Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Gaspard, S.; Oujja, M.; Rebollar, E.; Abrusci, C.; Catalina, F.; Castillejo, M.

2007-12-01

The emulsion-coated transparent plastic-base film has been the main carrier for production and preservation of motion picture contents since the 19th century. The knowledge of the composition of black and white silver gelatine cinematographic films is of great importance for the characterization of the photographic process and for identifying the optimum conditions for conservation. A cinematographic film is a multi-component system that consists of a layer of photographic emulsion overcoating a polymeric support (plasticized cellulose triacetate) and a protective transparent cross-linked gelatine layer coating the emulsion. In the present work, Laser Induced Breakdown Spectroscopy (LIBS) is used to characterize the composition of the materials of cinematographic films. LIB spectra of film samples and of different individual film components, polymeric support and reference gelatines, were acquired in vacuum by excitation at 266 nm (Q-switched Nd:YAG laser, 6 ns, 10 Hz). In the cinematographic film, silver lines from the light-sensitive silver halide salts of the photographic emulsion are accompanied by iron, lead, chrome and phosphorus lines. Iron and lead are constituents of film developers, chrome is included in the composition of the hardening agents and phosphorus has its origin in the plasticizer used in the polymeric support. By applying successive pulses on the same spot of the film sample, it was possible to observe through stratigraphic analysis the different layers composition. Additionally, the results obtained reveal the analytical capacity of LIBS for the study and classification of the different gelatine types and qualities used for the protecting layer and the photographic emulsion.

Positron Annihilation in Insulating Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asoka-Kumar, P; Sterne, PA

2002-10-18

We describe positron results from a wide range of insulating materials. We have completed positron experiments on a range of zeolite-y samples, KDP crystals, alkali halides and laser damaged SiO{sub 2}. Present theoretical understanding of positron behavior in insulators is incomplete and our combined theoretical and experimental approach is aimed at developing a predictive understanding of positrons and positronium annihilation characteristics in insulators. Results from alkali halides and alkaline-earth halides show that positrons annihilate with only the halide ions, with no apparent contribution from the alkali or alkaline-earth cations. This contradicts the results of our existing theory for metals, whichmore » predicts roughly equal annihilation contributions from cation and anion. We also present result obtained using Munich positron microprobe on laser damaged SiO{sub 2} samples.« less

Laser-Induced Breakdown Spectroscopy of Cinematographic Film

NASA Astrophysics Data System (ADS)

Oujja, M.; Abrusci, C.; Gaspard, S.; Rebollar, E.; Amo, A. del; Catalina, F.; Castillejo, M.

Laser-induced breakdown spectroscopy (LIBS) was used to characterize the composition of black-and-white, silver-gelatine photographic films. LIB spectra of samples and reference gelatine (of various gel strengths, Bloom values 225 and 75 and crosslinking degrees) were acquired in vacuum by excitation at 266 nm. The elemental composition of the gelatine used in the upper protective layer and in the underlying emulsion is revealed by the stratigraphic analysis carried out by delivering successive pulses on the same spot of the sample. Silver (Ag) lines from the light-sensitive silver halide salts are accompanied by iron, lead and chrome lines. Fe and Pb are constituents of film developers and Cr is included in the hardening agent. The results demonstrate the analytical capacity of LIBS for study and classification of different gelatine types and the sensitivity of the technique to minor changes in gelatine composition. In addition LIBS analysis allows extracting important information on the chemicals used as developers and hardeners of archival cinematographic films.

Theoretical Study on Sers of Wagging Vibrations of Benzyl Radical Adsorbed on Silver Electrodes

NASA Astrophysics Data System (ADS)

Wu, De-Yin; Chen, Yan-Li; Tian, Zhong-Qun

2016-06-01

Electrochemical surface-enhanced Raman spectroscopy (EC-SERS) has been used to characterize adsorbed species widely but reaction intermediates rarely on electrodes. In previous studies, the observed SERS signals were proposed from surface benzyl species due to the electrochemical reduction of benzyl chloride on silver electrode surfaces. In this work, we reinvestigated the vibrational assignments of benzyl chloride and benzyl radical as the reaction intermediate. On the basis of density functional theoretical (DFT) calculations and normal mode analysis, our systematical results provide more reasonable new assignments for both surface species. Further, we investigated adsorption configurations, binding energies, and vibrational frequency shifts of benzyl radical interacting with silver. Our calculated results show that the wagging vibration displays significant vibrational frequency shift, strong coupling with some intramolecular modes in the phenyl ring, and significant changes in intensity of Raman signals. The study also provides absolute Raman intensity in benzyl halides and discuss the enhancement effect mainly due to the binding interaction with respect to free benzyl radical.

NREL Postdoc Awarded for Work on Breakthrough Solar Technology | News |

Science.gov Websites

widespread, new research must further these trends. One type of materials-halide perovskites-shows promise to group of Joseph M. Luther, working to develop a better understanding of halide perovskite materials fostered," Christians said. "This fellowship gives me the freedom to interact with a wide group

Lead halide perovskites: Crystal-liquid duality, phonon glass electron crystals, and large polaron formation

PubMed Central

Miyata, Kiyoshi; Atallah, Timothy L.; Zhu, X.-Y.

2017-01-01

Lead halide perovskites have been demonstrated as high performance materials in solar cells and light-emitting devices. These materials are characterized by coherent band transport expected from crystalline semiconductors, but dielectric responses and phonon dynamics typical of liquids. This “crystal-liquid” duality implies that lead halide perovskites belong to phonon glass electron crystals, a class of materials believed to make the most efficient thermoelectrics. We show that the crystal-liquid duality and the resulting dielectric response are responsible for large polaron formation and screening of charge carriers, leading to defect tolerance, moderate charge carrier mobility, and radiative recombination properties. Large polaron formation, along with the phonon glass character, may also explain the marked reduction in hot carrier cooling rates in these materials. PMID:29043296

Entropy in halide perovskites

NASA Astrophysics Data System (ADS)

Katan, Claudine; Mohite, Aditya D.; Even, Jacky

2018-05-01

Claudine Katan, Aditya D. Mohite and Jacky Even discuss the possible impact of various entropy contributions (stochastic structural fluctuations, anharmonicity and lattice softness) on the optoelectronic properties of halide perovskite materials and devices.

Construction of a new selective coated disk electrode for Ag (I) based on modified polypyrrole-carbon nanotubes composite with new lariat ether.

PubMed

Abbaspour, A; Tashkhourian, J; Ahmadpour, S; Mirahmadi, E; Sharghi, H; Khalifeh, R; Shahriyari, M R

2014-01-01

A poly (vinyl chloride) (PVC) matrix membrane ion-selective electrode for silver (I) ion is fabricated based on modified polypyrrole - multiwalled carbon nanotubes composite with new lariat ether. This sensor has a Nernstian slope of 59.4±0.5mV/decade over a wide linear concentration range of 1.0×10(-7) to 1.0×10(-1)molL(-1) for silver (I) ion. It has a short response time of about 8.0s and can be used for at least 50days. The detection limit is 9.3×10(-8)molL(-1) for silver (I) ion, and the electrode was applicable in the wide pH range of 1.6 -7.7. The electrode shows good selectivity for silver ion against many cations such as Hg (II), which usually imposes serious interference in the determination of silver ion concentration. The use of multiwalled carbon nanotubes (MWCNTs) in a polymer matrix improves the linear range and sensitivity of the electrode. In addition by coating the solid contact with a layer of the polypyrrole (Ppy) before coating the membrane on it, not only did it reduce the drift in potential, but a shorter response time was also resulted. The proposed electrode was used as an indicator electrode for potentiometric titration of silver ions with chloride anions and in the titration of mixed halides. This electrode was successfully applied for the determination of silver ions in silver sulphadiazine as a burning cream. © 2013.

Simplified dichromated gelatin hologram recording process

NASA Technical Reports Server (NTRS)

Georgekutty, Tharayil G.; Liu, Hua-Kuang

1987-01-01

A simplified method for making dichromated gelatin (DCG) holographic optical elements (HOE) has been discovered. The method is much less tedious and it requires a period of processing time comparable with that for processing a silver halide hologram. HOE characteristics including diffraction efficiency (DE), linearity, and spectral sensitivity have been quantitatively investigated. The quality of the holographic grating is very high. Ninety percent or higher diffraction efficiency has been achieved in simple plane gratings made by this process.

Bio-analytical applications of mid-infrared spectroscopy using silver halide fiber-optic probes1

NASA Astrophysics Data System (ADS)

Heise, H. M.; Küpper, L.; Butvina, L. N.

2002-10-01

Infrared-spectroscopy has proved to be a powerful method for the study of various biomedical samples, in particular for in-vitro analysis in the clinical laboratory and for non-invasive diagnostics. In general, the analysis of biofluids such as whole blood, urine, microdialysates and bioreactor broth media takes advantage of the fact that a multitude of analytes can be quantified simultaneously and rapidly without the need for reagents. Progress in the quality of infrared silver halide fibers enabled us to construct several flexible fiber-optic probes of different geometries, which are particularly suitable for the measurement of small biosamples. Recent trends show that dry film measurements by mid-infrared spectroscopy could revolutionize analytical tools in the clinical chemistry laboratory, and an example is given. Infrared diagnostic tools show a promising potential for patients, and minimal-invasive blood glucose assays or skin tissue pathology in particular cannot be left out using mid-infrared fiber-based probes. Other applications include the measurement of skin samples including penetration studies of vitamins and constituents of cosmetic cream formulations. A further field is the micro-domain analysis of biopsy samples from bog mummified corpses, and recent results on the chemistry of dermis and hair samples are reported. Another field of application, for which results are reported, is food analysis and bio-reactor monitoring.

Observation of Enhanced Hole Extraction in Br Concentration Gradient Perovskite Materials.

PubMed

Kim, Min-Cheol; Kim, Byeong Jo; Son, Dae-Yong; Park, Nam-Gyu; Jung, Hyun Suk; Choi, Mansoo

2016-09-14

Enhancing hole extraction inside the perovskite layer is the key factor for boosting photovoltaic performance. Realization of halide concentration gradient perovskite materials has been expected to exhibit rapid hole extraction due to the precise bandgap tuning. Moreover, a formation of Br-rich region on the tri-iodide perovskite layer is expected to enhance moisture stability without a loss of current density. However, conventional synthetic techniques of perovskite materials such as the solution process have not achieved the realization of halide concentration gradient perovskite materials. In this report, we demonstrate the fabrication of Br concentration gradient mixed halide perovskite materials using a novel and facile halide conversion method based on vaporized hydrobromic acid. Accelerated hole extraction and enhanced lifetime due to Br gradient was verified by observing photoluminescence properties. Through the combination of secondary ion mass spectroscopy and transmission electron microscopy with energy-dispersive X-ray spectroscopy analysis, the diffusion behavior of Br ions in perovskite materials was investigated. The Br-gradient was found to be eventually converted into a homogeneous mixed halide layer after undergoing an intermixing process. Br-substituted perovskite solar cells exhibited a power conversion efficiency of 18.94% due to an increase in open circuit voltage from 1.08 to 1.11 V and an advance in fill-factor from 0.71 to 0.74. Long-term stability was also dramatically enhanced after the conversion process, i.e., the power conversion efficiency of the post-treated device has remained over 97% of the initial value under high humid conditions (40-90%) without any encapsulation for 4 weeks.

Effect of Halide Composition on the Photochemical Stability of Perovskite Photovoltaic Materials.

PubMed

Misra, Ravi K; Ciammaruchi, Laura; Aharon, Sigalit; Mogilyansky, Dmitry; Etgar, Lioz; Visoly-Fisher, Iris; Katz, Eugene A

2016-09-22

The photochemical stability of encapsulated films of mixed halide perovskites with a range of MAPb(I 1-x Br x ) 3 (MA=methylammonium) compositions (solid solutions) was investigated under accelerated stressing using concentrated sunlight. The relevance of accelerated testing to standard operational conditions of solar cells was confirmed by comparison to degradation experiments under outdoor sunlight exposure. We found that MAPbBr 3 films exhibited no degradation, while MAPbI 3 and mixed halide MAPb(I 1-x Br x ) 3 films decomposed yielding crystallization of inorganic PbI 2 accompanied by degradation of the perovskite solar light absorption, with faster absorption degradation in mixed halide films. The crystal coherence length was found to correlate with the stability of the films. We postulate that the introduction of Br into the mixed halide solid solution stressed its structure and induced more structural defects and/or grain boundaries compared to pure halide perovskites, which might be responsible for the accelerated degradation. Hence, the cause for accelerated degradation may be the increased defect density rather than the chemical composition of the perovskite materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Computer simulation of selective absorption of radiation by the components of a light-scattering layer

NASA Astrophysics Data System (ADS)

Kozakov, O. N.

2002-10-01

A method of calculating the partial characteristics of radiation absorption by the components of light-scattering disperse layers is proposed. This method is based on statistical modeling (the Monte Carlo method). The absorptivities of photographic gelatin and silver bromide microcrystals and the corresponding distributions of the absorbed energy over the layer thickness are calculated using the example of an interaction between actinic radiation and silver halide photographic layers in the wavelength range λ=200 440 nm. The following structural parameters of the photographic layer are used in the calculation: the mean size of emulsion crystals d=0.5 μm; the polydispersity C V =25%; the volume concentrations C V =10, 20, and 30%; and the thickness of the emulsion layer H=10 μm.

Room-temperature solution-processed and metal oxide-free nano-composite for the flexible transparent bottom electrode of perovskite solar cells

NASA Astrophysics Data System (ADS)

Lu, Haifei; Sun, Jingsong; Zhang, Hong; Lu, Shunmian; Choy, Wallace C. H.

2016-03-01

The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies.The exploration of low-temperature and solution-processed charge transporting and collecting layers can promote the development of low-cost and large-scale perovskite solar cells (PVSCs) through an all solution process. Here, we propose a room-temperature solution-processed and metal oxide-free nano-composite composed of a silver nano-network and graphene oxide (GO) flawless film for the transparent bottom electrode of a PVSC. Our experimental results show that the amount of GO flakes play a critical role in forming the flawless anti-corrosive barrier in the silver nano-network through a self-assembly approach under ambient atmosphere, which can effectively prevent the penetration of liquid or gaseous halides and their corrosion against the silver nano-network underneath. Importantly, we simultaneously achieve good work function alignment and surface wetting properties for a practical bottom electrode by controlling the degree of reduction of GO flakes. Finally, flexible PVSC adopting the room-temperature and solution-processed nano-composite as the flexible transparent bottom electrode has been demonstrated on a polyethylene terephthalate (PET) substrate. As a consequence, the demonstration of our room-temperature solution-processed and metal oxide-free flexible transparent bottom electrode will contribute to the emerging large-area flexible PVSC technologies. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr00011h

Real-time gray-scale photolithography for fabrication of continuous microstructure

NASA Astrophysics Data System (ADS)

Peng, Qinjun; Guo, Yongkang; Liu, Shijie; Cui, Zheng

2002-10-01

A novel real-time gray-scale photolithography technique for the fabrication of continuous microstructures that uses a LCD panel as a real-time gray-scale mask is presented. The principle of design of the technique is explained, and computer simulation results based on partially coherent imaging theory are given for the patterning of a microlens array and a zigzag grating. An experiment is set up, and a microlens array and a zigzag grating on panchromatic silver halide sensitized gelatin with trypsinase etching are obtained.

Holographic optical element for laser soldering

NASA Astrophysics Data System (ADS)

Nakahara, Sumio; Hayashi, Tatsuya; Sudou, Noriyuki; Hisada, Shigeyoshi; Fujita, Takeyoshi

2002-02-01

Experimental studies on the characteristics of holographic lens were carried out, aiming at the simultaneous soldering of multi-spots in electronic assembly by the use of YAG laser. Holograms were recorded on the commercial available photographic plates, and converted into transparent phase type holographic lens by chemical processing. The dependencies of the diffraction efficiency on the recording conditions and two chemical treatment methods of silver halide sensitized gelatin and rehalogenating bleaching were examined in CW YAG laser system ((lambda) equals 1.06 micrometers ).

Holographic Recording and Applications of Multiplexed Volume Bragg Gratings in Photo-Thermo-Refractive Glass

DTIC Science & Technology

2014-10-06

grating or by a wetting process to create a phase hologram [26]. The photo-sensitivity is lower compared to silver halide emulsions at 0.1-1 J/cm2...spectral amplitude and phase of optical signals in fiber. This is useful in dispersion compensation for long optical networks as well as for high...and minimum phase distortion across the aperture. The polynomials for RMSE wavefront are of the same form but use different coefficients. The phase

Surface passivation of mixed-halide perovskite CsPb(BrxI1-x)3 nanocrystals by selective etching for improved stability.

PubMed

Jing, Qiang; Zhang, Mian; Huang, Xiang; Ren, Xiaoming; Wang, Peng; Lu, Zhenda

2017-06-08

In recent years, there has been an unprecedented rise in the research of halide perovskites because of their important optoelectronic applications, including photovoltaic cells, light-emitting diodes, photodetectors and lasers. The most pressing question concerns the stability of these materials. Here faster degradation and PL quenching are observed at higher iodine content for mixed-halide perovskite CsPb(Br x I 1-x ) 3 nanocrystals, and a simple yet effective method is reported to significantly enhance their stability. After selective etching with acetone, surface iodine is partially etched away to form a bromine-rich surface passivation layer on mixed-halide perovskite nanocrystals. This passivation layer remarkably stabilizes the nanocrystals, making their PL intensity improved by almost three orders of magnitude. It is expected that a similar passivation layer can also be applied to various other kinds of perovskite materials with poor stability issues.

Heat capacity of molten halides.

PubMed

Redkin, Alexander A; Zaikov, Yurii P; Korzun, Iraida V; Reznitskikh, Olga G; Yaroslavtseva, Tatiana V; Kumkov, Sergey I

2015-01-15

The heat capacities of molten salts are very important for their practical use. Experimental investigation of this property is challenging because of the high temperatures involved and the corrosive nature of these materials. It is preferable to combine experimental investigations with empirical relationships, which allows for the evaluation of the heat capacity of molten salt mixtures. The isobaric molar heat capacities of all molten alkali and alkaline-earth halides were found to be constant for each group of salts. The value depends on the number of atoms in the salt, and the molar heat capacity per atom is constant for all molten halide salts with the exception of the lithium halides. The molar heat capacities of molten halides do not change when the anions are changed.

First-principles Investigation of the Structure, Mobility and Optical Properties of Self-Trapped Excitons in Alkali Metal, Lanthanum and Barium Halide Scintillators

NASA Astrophysics Data System (ADS)

Bizarri, Gregory; Del Ben, Mauro; Bourret, Edith; Canning, Andrew

The performance of new and improved materials for gamma ray scintillator detectors is dependant on multiple factors such as quantum efficiency, energy transport etc. In halide scintillator materials the energy transport is often impacted by self-trapped exciton (STE) formation and mobility. We present first-principles calculations at the hybrid density functional theory level for the structure, mobility and optical properties of STEs and their associated lattice defects (VK centers) in two important families of scintillator materials, alkali metal and lanthanum halides (AX and LaX). AX and LaX have been extensively characterized by experiments and serve as benchmark systems to assess the accuracy of our theoretical procedure. We show that hydrid functionals accurately predict the different types of self-trapped excitons (on and off-center) found in AX and LX materials in agreement with EPR experiments. We then applied this approach to perform preliminary studies on classes of new scintillator materials including the barium mixed halides and compared with our new experimental results. These studies have the potential to benefit the development of improved scintillator materials tailored for specific applications. This work is supported by the U.S. Department of Energy/NNSA/DNN R&D and is carried out at Lawrence Berkeley National Laboratory under Contract No. AC02-05CH11231.

Design of Lead-Free Inorganic Halide Perovskites for Solar Cells via Cation-Transmutation.

PubMed

Zhao, Xin-Gang; Yang, Ji-Hui; Fu, Yuhao; Yang, Dongwen; Xu, Qiaoling; Yu, Liping; Wei, Su-Huai; Zhang, Lijun

2017-02-22

Hybrid organic-inorganic halide perovskites with the prototype material of CH 3 NH 3 PbI 3 have recently attracted intense interest as low-cost and high-performance photovoltaic absorbers. Despite the high power conversion efficiency exceeding 20% achieved by their solar cells, two key issues-the poor device stabilities associated with their intrinsic material instability and the toxicity due to water-soluble Pb 2+ -need to be resolved before large-scale commercialization. Here, we address these issues by exploiting the strategy of cation-transmutation to design stable inorganic Pb-free halide perovskites for solar cells. The idea is to convert two divalent Pb 2+ ions into one monovalent M + and one trivalent M 3+ ions, forming a rich class of quaternary halides in double-perovskite structure. We find through first-principles calculations this class of materials have good phase stability against decomposition and wide-range tunable optoelectronic properties. With photovoltaic-functionality-directed materials screening, we identify 11 optimal materials with intrinsic thermodynamic stability, suitable band gaps, small carrier effective masses, and low excitons binding energies as promising candidates to replace Pb-based photovoltaic absorbers in perovskite solar cells. The chemical trends of phase stabilities and electronic properties are also established for this class of materials, offering useful guidance for the development of perovskite solar cells fabricated with them.

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber.

PubMed

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-05-11

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of -0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber.

Copper(I), silver(I) and gold(I) halide complexes with the dithioformamidinium dihalides

NASA Astrophysics Data System (ADS)

Peyronel, Giorgio; Malavasi, Wanda; Pignedoli, Anna

Some copper(I), silver(I) and gold(I) halide complexes with the dithioformamidinium dihalides (Tu 2X 2) were prepared and studied by infrared spectroscopy and conductometry: 3CuX.2Tu 2X 2(XCl,I), CuBr.Tu 2Br 2, 4CuBr.3.5Tu 2Br 2.MeOH, 2CuBr.Tu 2Br 2.0.66EtOH, 3CuI.2Tu 2I 2, 2AgCl.2.5Tu 2Cl 2, 3AgCl.2Tu 2Cl 2.0.5EtOH, 3AgCl.Tu 2Cl 2, 2AgBr.2Tu 2Br 2.0.5Tu 2(NO 3) 2.H 2O, AgBr.Tu 2Br 2, 4AgBr.Tu 2Br 2, 4AgI.0.5Tu 2I 2.EtOH, AuCl.1.5Tu 2Cl 2, 4AuCl.3.5Tu 2Cl 2.2DMF, AuBr.4Tu 2Br 2, AuBr.2Tu 2Br 2.1.5DMF, AuI.5Tu 2I 2, AuI.Tu 2I 2. A decrease of the ν(NH), δ(NH 2) and ν(CN 2) frequencies and an increase of the ν(CS) frequencies indicate an N-coordination of the dithioformamidinium cation to the metal ions; ν(MN) and ν(MX) frequencies are tentatively assigned in the far-infrared spectra.

Effects of Temperature and X-rays on Plastic Scintillating Fiber and Infrared Optical Fiber

PubMed Central

Lee, Bongsoo; Shin, Sang Hun; Jang, Kyoung Won; Yoo, Wook Jae

2015-01-01

In this study, we have studied the effects of temperature and X-ray energy variations on the light output signals from two different fiber-optic sensors, a fiber-optic dosimeter (FOD) based on a BCF-12 as a plastic scintillating fiber (PSF) and a fiber-optic thermometer (FOT) using a silver halide optical fiber as an infrared optical fiber (IR fiber). During X-ray beam irradiation, the scintillating light and IR signals were measured simultaneously using a dosimeter probe of the FOD and a thermometer probe of the FOT. The probes were placed in a beaker with water on the center of a hotplate, under variation of the tube potential of a digital radiography system or the temperature of the water in the beaker. From the experimental results, in the case of the PSF, the scintillator light output at the given tube potential decreased as the temperature increased in the temperature range from 25 to 60 °C. We demonstrated that commonly used BCF-12 has a significant temperature dependence of −0.263 ± 0.028%/°C in the clinical temperature range. Next, in the case of the IR fiber, the intensity of the IR signal was almost uniform at each temperature regardless of the tube potential range from 50 to 150 kVp. Therefore, we also demonstrated that the X-ray beam with an energy range used in diagnostic radiology does not affect the IR signals transmitted via a silver halide optical fiber. PMID:25970257

Nanocrystals of Cesium Lead Halide Perovskites (CsPbX₃, X = Cl, Br, and I): Novel Optoelectronic Materials Showing Bright Emission with Wide Color Gamut.

PubMed

Protesescu, Loredana; Yakunin, Sergii; Bodnarchuk, Maryna I; Krieg, Franziska; Caputo, Riccarda; Hendon, Christopher H; Yang, Ruo Xi; Walsh, Aron; Kovalenko, Maksym V

2015-06-10

Metal halides perovskites, such as hybrid organic-inorganic CH3NH3PbI3, are newcomer optoelectronic materials that have attracted enormous attention as solution-deposited absorbing layers in solar cells with power conversion efficiencies reaching 20%. Herein we demonstrate a new avenue for halide perovskites by designing highly luminescent perovskite-based colloidal quantum dot materials. We have synthesized monodisperse colloidal nanocubes (4-15 nm edge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors. Through compositional modulations and quantum size-effects, the bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410-700 nm. The photoluminescence of CsPbX3 nanocrystals is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90%, and radiative lifetimes in the range of 1-29 ns. The compelling combination of enhanced optical properties and chemical robustness makes CsPbX3 nanocrystals appealing for optoelectronic applications, particularly for blue and green spectral regions (410-530 nm), where typical metal chalcogenide-based quantum dots suffer from photodegradation.

Measurement of refractive index of photopolymer for holographic gratings

NASA Astrophysics Data System (ADS)

Watanabe, Eriko; Mizuno, Jun; Fujikawa, Chiemi; Kodate, Kashiko

2007-02-01

We have made attempts to measure directly the small-scale variation of optical path lengths in photopolymer samples. For those with uniform thickness, the measured quantity is supposed to be proportional to the refractive index of the photopolymer. The system is based on a Mach-Zehnder interferometer using phase-locking technique and measures the change in optical path length during the sample is scanned across the optical axis. The spatial resolution is estimated to be 2μm, which is limited by the sample thickness. The path length resolution is estimated to be 6nm, which corresponds to the change in refractive index less than 10 -3 for the sample of 10μm thick. The measurement results showed clearly that the refractive index of photopolymer is not simply proportional to the exposure energy, contrary to the conventional photosensitive materials such as silver halide emulsion and dichromated gelatine. They also revealed the refractive index fluctuation in uniformly exposed photopolymer sample, which explains the milky appearance that sometimes observed in thick samples.

Origin of Reversible Photoinduced Phase Separation in Hybrid Perovskites

NASA Astrophysics Data System (ADS)

Bischak, Connor G.; Hetherington, Craig L.; Wu, Hao; Aloni, Shaul; Ogletree, D. Frank; Limmer, David T.; Ginsberg, Naomi S.

2017-02-01

Nonequilibrium processes occurring in functional materials can significantly impact device efficiencies and are often difficult to characterize due to the broad range of length and time scales involved. In particular, mixed halide hybrid perovskites are promising for optoelectronics, yet the halides reversibly phase separate when photo-excited, significantly altering device performance. By combining nanoscale imaging and multiscale modeling, we elucidate the mechanism underlying this phenomenon, demonstrating that local strain induced by photo-generated polarons promotes halide phase separation and leads to nucleation of light-stabilized iodide-rich clusters. This effect relies on the unique electromechanical properties of hybrid materials, characteristic of neither their organic nor inorganic constituents alone. Exploiting photo-induced phase separation and other nonequilibrium phenomena in hybrid materials, generally, could enable new opportunities for expanding the functional applications in sensing, photoswitching, optical memory, and energy storage.

Metal-halide mixtures for latent heat energy storage

NASA Technical Reports Server (NTRS)

Chen, K.; Manvi, R.

1981-01-01

Alkali metal and alkali halide mixtures are identified which may be suitable for thermal energy storage at temperatures above 600 C. The use of metal-halides is appropriate because of their tendency to form two immiscible melts with a density difference, which reduces scale formation and solidification on heat transfer surfaces. Also, the accumulation of phase change material along the melt interface is avoided by the self-dispersing characteristic of some metal-halides, in particular Sr-SrCl2, Ba-BaCl2, and Ba-BaBr2 mixtures. Further advantages lie in their high thermal conductivities, ability to cope with thermal shock, corrosion inhibition, and possibly higher energy densities.

Advancement on Lead-Free Organic-Inorganic Halide Perovskite Solar Cells: A Review.

PubMed

Sani, Faruk; Shafie, Suhaidi; Lim, Hong Ngee; Musa, Abubakar Ohinoyi

2018-06-14

Remarkable attention has been committed to the recently discovered cost effective and solution processable lead-free organic-inorganic halide perovskite solar cells. Recent studies have reported that, within five years, the reported efficiency has reached 9.0%, which makes them an extremely promising and fast developing candidate to compete with conventional lead-based perovskite solar cells. The major challenge associated with the conventional perovskite solar cells is the toxic nature of lead (Pb) used in the active layer of perovskite material. If lead continues to be used in fabricating solar cells, negative health impacts will result in the environment due to the toxicity of lead. Alternatively, lead free perovskite solar cells could give a safe way by substituting low-cost, abundant and non toxic material. This review focuses on formability of lead-free organic-inorganic halide perovskite, alternative metal cations candidates to replace lead (Pb), and possible substitutions of organic cations, as well as halide anions in the lead-free organic-inorganic halide perovskite architecture. Furthermore, the review gives highlights on the impact of organic cations, metal cations and inorganic anions on stability and the overall performance of lead free perovskite solar cells.

Shape Evolution and Single Particle Luminescence of Organometal Halide Perovskite Nanocrystals

DOE PAGES

Zhu, Feng; Men, Long; Guo, Yijun; ...

2015-02-09

Organometallic halide perovskites CH 3NH 3PbX 3 (X = I, Br, Cl) have quickly become one of the most promising semiconductors for solar cells, with photovoltaics made of these materials reaching power conversion efficiencies of near 20%. Improving our ability to harness the full potential of organometal halide perovskites will require more controllable syntheses that permit a detailed understanding of their fundamental chemistry and photophysics. In our manuscript, we systematically synthesize CH 3NH 3PbX 3 (X = I, Br) nanocrystals with different morphologies (dots, rods, plates or sheets) by using different solvents and capping ligands. CH 3NH 3PbX 3 nanowiresmore » and nanorods capped with octylammonium halides show relatively higher photoluminescence (PL) quantum yields and long PL lifetimes. CH 3NH 3PbI 3 nanowires monitored at the single particle level show shape-correlated PL emission across whole particles, with little photobleaching observed and very few off periods. Our work highlights the potential of low-dimensional organometal halide perovskite semiconductors in constructing new porous and nanostructured solar cell architectures, as well as in applying these materials to other fields such as light-emitting devices and single particle imaging and tracking.« less

Determination of the structural phase and octahedral rotation angle in halide perovskites

NASA Astrophysics Data System (ADS)

dos Reis, Roberto; Yang, Hao; Ophus, Colin; Ercius, Peter; Bizarri, Gregory; Perrodin, Didier; Shalapska, Tetiana; Bourret, Edith; Ciston, Jim; Dahmen, Ulrich

2018-02-01

A key to the unique combination of electronic and optical properties in halide perovskite materials lies in their rich structural complexity. However, their radiation sensitive nature limits nanoscale structural characterization requiring dose efficient microscopic techniques in order to determine their structures precisely. In this work, we determine the space-group and directly image the Br halide sites of CsPbBr3, a promising material for optoelectronic applications. Based on the symmetry of high-order Laue zone reflections of convergent-beam electron diffraction, we identify the tetragonal (I4/mcm) structural phase of CsPbBr3 at cryogenic temperature. Electron ptychography provides a highly sensitive phase contrast measurement of the halide positions under low electron-dose conditions, enabling imaging of the elongated Br sites originating from the out-of-phase octahedral rotation viewed along the [001] direction of I4/mcm persisting at room temperature. The measurement of these features and comparison with simulations yield an octahedral rotation angle of 6.5°(±1.5°). The approach demonstrated here opens up opportunities for understanding the atomic scale structural phenomena applying advanced characterization tools on a wide range of radiation sensitive halide-based all-inorganic and hybrid organic-inorganic perovskites.

Analytical energy gradient based on spin-free infinite-order Douglas-Kroll-Hess method with local unitary transformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakajima, Yuya; Seino, Junji; Nakai, Hiromi, E-mail: nakai@waseda.jp

In this study, the analytical energy gradient for the spin-free infinite-order Douglas-Kroll-Hess (IODKH) method at the levels of the Hartree-Fock (HF), density functional theory (DFT), and second-order Møller-Plesset perturbation theory (MP2) is developed. Furthermore, adopting the local unitary transformation (LUT) scheme for the IODKH method improves the efficiency in computation of the analytical energy gradient. Numerical assessments of the present gradient method are performed at the HF, DFT, and MP2 levels for the IODKH with and without the LUT scheme. The accuracies are examined for diatomic molecules such as hydrogen halides, halogen dimers, coinage metal (Cu, Ag, and Au) halides,more » and coinage metal dimers, and 20 metal complexes, including the fourth–sixth row transition metals. In addition, the efficiencies are investigated for one-, two-, and three-dimensional silver clusters. The numerical results confirm the accuracy and efficiency of the present method.« less

Image analysis for material characterisation

NASA Astrophysics Data System (ADS)

Livens, Stefan

In this thesis, a number of image analysis methods are presented as solutions to two applications concerning the characterisation of materials. Firstly, we deal with the characterisation of corrosion images, which is handled using a multiscale texture analysis method based on wavelets. We propose a feature transformation that deals with the problem of rotation invariance. Classification is performed with a Learning Vector Quantisation neural network and with combination of outputs. In an experiment, 86,2% of the images showing either pit formation or cracking, are correctly classified. Secondly, we develop an automatic system for the characterisation of silver halide microcrystals. These are flat crystals with a triangular or hexagonal base and a thickness in the 100 to 200 nm range. A light microscope is used to image them. A novel segmentation method is proposed, which allows to separate agglomerated crystals. For the measurement of shape, the ratio between the largest and the smallest radius yields the best results. The thickness measurement is based on the interference colours that appear for light reflected at the crystals. The mean colour of different thickness populations is determined, from which a calibration curve is derived. With this, the thickness of new populations can be determined accurately.

High-efficiency volume holograms recording on acrylamide and N,N‧methylene-bis-acrylamide photopolymer with pulsed laser

NASA Astrophysics Data System (ADS)

Gallego, S.; Ortuño, M.; García, C.; Neipp, C.; Beléndez, A.; Pascual, I.

2005-11-01

In order to achieve a better understanding of the mechanisms of hologram formation and higher diffraction efficiencies in volume gratings stored in acrylamide based photopolymers, a crosslinker (N,N'methylene-bis-acrylamide) has been incorporated in the photopolymer to record holograms by pulsed laser exposure. The presence of this component increases the polymerization rate and refractive index modulation. The recording was performed using a holographic copying process. The original was a grating of 1000?lines/mm processed using silver halide sensitized gelatin. First, the effect of the pulse fluence was investigated. When the pulse fluence was optimized, the results obtained using the new composition of material were compared with those using the composition without a crosslinker. Using a pulsed laser at 532?nm the photopolymer without crosslinker presented diffraction efficiencies slightly less than 60%. On the other hand, when the crosslinker was introduced in the photopolymer composition, the diffraction efficiencies achieved were higher than 85%. The non-linearity of the material's response was also studied comparing the energetic sensitivity, diffraction efficiencies and index modulation of gratings recorded with pulsed and continuous laser exposure. This study was performed fitting the angular scan of each grating using Kogelnik's theory.

A low temperature furnace for solution crystal growth on the International Space Station

NASA Astrophysics Data System (ADS)

Baç, Nurcan; Harpster, Joseph; Maston, Robert A.; Sacco, Albert

2000-01-01

The Zeolite Crystal Growth Furnace Unit (ZCG-FU) is the first module in an integrated payload designed for low temperature crystal growth in solutions on the International Space Station (ISS). This payload is scheduled to fly on the ISS flight 7A.1 in an EXPRESS rack. Its name originated from early shuttle flight experiments limited to the growth of zeolite crystals but has since grown to include other materials of significant commercial interest using the solution method of crystal growth. Zeolites, ferroelectrics, piezeoelectrics and silver halides are some of the materials considered. The ZCG-FU experiment consists of a furnace unit and its electronic control system, and mechanically complex, crystal growth autoclaves suitable for use with a particular furnace and solution. The ZCG facility is being designed to grow into four independent furnaces controlled by IZECS (Improved Zeolite Electronic Control System). IZECS provides monitoring of critical parameters, data logging, safety monitoring, air-to-ground control and operator interfacing. It is suitable for controlling the four furnaces either individually or all at one time. It also contains the power management solid-state drivers and switches for the ZCG-FU furnace. The furnace contains 19 tubes operating at three different temperature zones. .

Optical nonlinearity in gelatin layer film containing Au nanoparticles

NASA Astrophysics Data System (ADS)

Hirose, Tomohiro; Arisawa, Michiko; Omatsu, Takashige; Kuge, Ken'ichi; Hasegawa, Akira; Tateda, Mitsuhiro

2002-09-01

We demonstrate a novel technique to fabricate a gelatin film containing Au-nano-particles. The technique is based on silver halide photographic development. We investigated third-order non-linearity of the film by forward-four-wave-mixing technique. Peak absorption appeared at the wavelength of 560nm. Self-diffraction by the use of third order nonlinear grating formed by intense pico-second pulses was observed. Experimental diffraction efficiency was proportional to the square of the pump intensity. Third-order susceptibility c(3) of the film was estimated to be 1.8?~10^-7esu.

Photopolymer holographic recording material

NASA Astrophysics Data System (ADS)

Lawrence, J. R.; O'Neill, F. T.; Sheridan, J. T.

Photopolymers are promising materials for use in holography. They have many advantages, such as ease of preparation, and are capable of efficiencies of up to 100%. A disadvantage of these materials is their inability to record high spatial frequency gratings when compared to other materials such as dichromated gelatin and silver halide photographic emulsion. Until recently, the drop off at high spatial frequencies of the material response was not predicted by any of the diffusion based models available. It has recently been proposed that this effect is due to polymer chains growing away from their initiation point and causing a smeared profile to be recorded. This is termed a non-local material response. Simple analytic expressions have been derived using this model and fits to experimental data have allowed values to be estimated for material parameters such as the diffusion coefficient of monomer, the ratio of polymerisation rate to diffusion rate and the distance that the polymer chains spread during holographic recording. The model predicts that the spatial frequency response might be improved by decreasing the mean polymer chain lengths and/or by increasing the mobility of the molecules used in the material. The experimental work carried out to investigate these predictions is reported here. This work involved (a) the changing of the molecular weights of chemical components within the material (dyes and binders) and (b) the addition of a chemical retarder in order to shorten the polymer chains, thereby decreasing the extent of the non-local effect. Although no significant improvement in spatial frequency response was observed the model appears to offer an improved understanding of the operation of the material.

Zero-Dimensional Cesium Lead Halides: History, Properties, and Challenges

PubMed Central

2018-01-01

Over the past decade, lead halide perovskites (LHPs) have emerged as new promising materials in the fields of photovoltaics and light emission due to their facile syntheses and exciting optical properties. The enthusiasm generated by LHPs has inspired research in perovskite-related materials, including the so-called “zero-dimensional cesium lead halides”, which will be the focus of this Perspective. The structure of these materials is formed of disconnected lead halide octahedra that are stabilized by cesium ions. Their optical properties are dominated by optical transitions that are localized within the individual octahedra, hence the title “‘zero-dimensional perovskites”. Controversial results on their physical properties have recently been reported, and the true nature of their photoluminescence is still unclear. In this Perspective, we will take a close look at these materials, both as nanocrystals and as bulk crystals/thin films, discuss the contrasting opinions on their properties, propose potential applications, and provide an outlook on future experiments. PMID:29652149

Chloride, bromide and iodide scintillators with europium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuravleva, Mariya; Yang, Kan

A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has beenmore » studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.« less

Synthesis and immobilization of Ag(0) nanoparticles on diazonium modified electrodes: SECM and cyclic voltammetry studies of the modified interfaces.

PubMed

Noël, Jean-Marc; Zigah, Dodzi; Simonet, Jacques; Hapiot, Philippe

2010-05-18

A versatile method was used to prepare modified surfaces on which metallic silver nanoparticles are immobilized on an organic layer. The preparation method takes advantage, on one hand, of the activated reactivity of some alkyl halides with Ag-Pd alloys to produce metallic silver nanoparticles and, on the other hand, of the facile production of an anchoring polyphenyl acetate layer by the electrografting of substituted diazonium salts on carbon surfaces. Transport properties inside such modified layers were investigated by cyclic voltammetry, scanning electrochemical microscopy (SECM) in feedback mode, and conducting AFM imaging for characterizing the presence and nature of the conducting pathways. The modification of the blocking properties of the surface (or its conductivity) was found to vary to a large extent on the solvents used for surface examination (H(2)O, CH(2)Cl(2), and DMF).

Silver-halide sensitized gelatin (SHSG) processing method for pulse holograms recorded on VRP plates

NASA Astrophysics Data System (ADS)

Evstigneeva, Maria K.; Drozdova, Olga V.; Mikhailov, Viktor N.

2002-06-01

One of the most important area of holograph applications is display holography. In case of pulse recording the requirement for vibration stability is easier than compared to CW exposure. At the same time it is widely known that the behavior of sliver-halide holographic materials strongly depends on the exposure duration. In particular the exposure sensitivity drastically decreases under nanosecond pulse duration. One of the effective ways of the diffraction efficiency improvement is SHSG processing method. This processing scheme is based on high modulation of refractive index due to microvoids appearance inside emulsion layer. It should be mentioned that the SHSG method was used earlier only in the cases when the holograms were recorded by use of CW lasers. This work is devoted to the investigation of SHSG method for pulse hologram recording on VRP plates. We used a pulsed YLF:Nd laser with pulse duration of 25 nanoseconds and wavelength of 527 nm. Both transmission and reflection holograms were recorded. The different kinds of bleaching as well as developing solutions were investigated. Our final processing scheme includes the following stages: 1) development in non-tanning solution, 2) rehalogenating bleach, 3) intermediate alcohol drying, 4) uniform second exposure, 5) second development in diluted developer, 6) reverse bleaching, 7) fixing and 8) gradient drying in isopropyl alcohol. Diffraction efficiency of transmission holograms was of about 60 percent and reflection mirror holograms was of about 45 percent. Thus we have demonstrated the SHSG processing scheme for producing effective holograms on VRP plates under pulse exposure.

Electrochemical Exfoliation of Graphite in Aqueous Sodium Halide Electrolytes toward Low Oxygen Content Graphene for Energy and Environmental Applications.

PubMed

Munuera, J M; Paredes, J I; Enterría, M; Pagán, A; Villar-Rodil, S; Pereira, M F R; Martins, J I; Figueiredo, J L; Cenis, J L; Martínez-Alonso, A; Tascón, J M D

2017-07-19

Graphene and graphene-based materials have shown great promise in many technological applications, but their large-scale production and processing by simple and cost-effective means still constitute significant issues in the path of their widespread implementation. Here, we investigate a straightforward method for the preparation of a ready-to-use and low oxygen content graphene material that is based on electrochemical (anodic) delamination of graphite in aqueous medium with sodium halides as the electrolyte. Contrary to previous conflicting reports on the ability of halide anions to act as efficient exfoliating electrolytes in electrochemical graphene exfoliation, we show that proper choice of both graphite electrode (e.g., graphite foil) and sodium halide concentration readily leads to the generation of large quantities of single-/few-layer graphene nanosheets possessing a degree of oxidation (O/C ratio down to ∼0.06) lower than that typical of anodically exfoliated graphenes obtained with commonly used electrolytes. The halide anions are thought to play a role in mitigating the oxidation of the graphene lattice during exfoliation, which is also discussed and rationalized. The as-exfoliated graphene materials exhibited a three-dimensional morphology that was suitable for their practical use without the need to resort to any kind of postproduction processing. When tested as dye adsorbents, they outperformed many previously reported graphene-based materials (e.g., they adsorbed ∼920 mg g -1 for methyl orange) and were useful sorbents for oils and nonpolar organic solvents. Supercapacitor cells assembled directly from the as-exfoliated products delivered energy and power density values (up to 15.3 Wh kg -1 and 3220 W kg -1 , respectively) competitive with those of many other graphene-based devices but with the additional advantage of extreme simplicity of preparation.

FRACTIONAL DISTILLATION SEPARATION OF PLUTONIUM VALUES FROM LIGHT ELEMENT VALUES

DOEpatents

Cunningham, B.B.

1957-12-17

A process is described for removing light element impurities from plutonium. It has been found that plutonium contaminated with impurities may be purified by converting the plutonium to a halide and purifying the halide by a fractional distillation whereby impurities may be distilled from the plutonium halide. A particularly effective method includes the step of forming a lower halide such as the trior tetrahalide and distilling the halide under conditions such that no decomposition of the halide occurs. Molecular distillation methods are particularly suitable for this process. The apparatus may comprise an evaporation plate with means for heating it and a condenser surface with means for cooling it. The condenser surface is placed at a distance from the evaporating surface less than the mean free path of molecular travel of the material being distilled at the pressure and temperature used. The entire evaporating system is evacuated until the pressure is about 10/sup -4/ millimeters of mercury. A high temperuture method is presented for sealing porous materials such as carbon or graphite that may be used as a support or a moderator in a nuclear reactor. The carbon body is subjected to two surface heats simultaneously in an inert atmosphere; the surface to be sealed is heated to 1500 degrees centigrade; and another surface is heated to 300 degrees centigrade, whereupon the carbon vaporizes and flows to the cooler surface where it is deposited to seal that surface. This method may be used to seal a nuclear fuel in the carbon structure.

Photovoltaic Rudorffites: Lead-Free Silver Bismuth Halides Alternative to Hybrid Lead Halide Perovskites.

PubMed

Turkevych, Ivan; Kazaoui, Said; Ito, Eisuke; Urano, Toshiyuki; Yamada, Koji; Tomiyasu, Hiroshi; Yamagishi, Hideo; Kondo, Michio; Aramaki, Shinji

2017-10-09

Hybrid CPbX 3 (C: Cs, CH 3 NH 3 ; X: Br, I) perovskites possess excellent photovoltaic properties but are highly toxic, which hinders their practical application. Unfortunately, all Pb-free alternatives based on Sn and Ge are extremely unstable. Although stable and non-toxic C 2 ABX 6 double perovskites based on alternating corner-shared AX 6 and BX 6 octahedra (A=Ag, Cu; B=Bi, Sb) are possible, they have indirect and wide band gaps of over 2 eV. However, is it necessary to keep the corner-shared perovskite structure to retain good photovoltaic properties? Here, we demonstrate another family of photovoltaic halides based on edge-shared AX 6 and BX 6 octahedra with the general formula A a B b X x (x=a+3 b) such as Ag 3 BiI 6 , Ag 2 BiI 5 , AgBiI 4 , AgBi 2 I 7 . As perovskites were named after their prototype oxide CaTiO 3 discovered by Lev Perovski, we propose to name these new ABX halides as rudorffites after Walter Rüdorff, who discovered their prototype oxide NaVO 2 . We studied structural and optoelectronic properties of several highly stable and promising Ag-Bi-I photovoltaic rudorffites that feature direct band gaps in the range of 1.79-1.83 eV and demonstrated a proof-of-concept FTO/c-m-TiO 2 /Ag 3 BiI 6 /PTAA/Au (FTO: fluorine-doped tin oxide, PTAA: poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], c: compact, m: mesoporous) solar cell with photoconversion efficiency of 4.3 %. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Isenberg, Arnold O.; Ruka, Roswell J.

1986-01-01

A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Isenberg, Arnold O.; Ruka, Roswell J.; Zymboly, Gregory E.

1985-01-01

A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

Protective interlayer for high temperature solid electrolyte electrochemical cells

DOEpatents

Isenberg, Arnold O.; Ruka, Roswell J.

1987-01-01

A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

Antimicrobial properties of metal and metal-halide nanoparticles and their potential applications

NASA Astrophysics Data System (ADS)

Torrey, Jason Robert

Heavy metals, including silver and copper, have been known to possess antimicrobial properties against bacterial, fungal, and viral pathogens. Metal nanoparticles (aggregations of metal atoms 1-200 nm in size) have recently become the subject of intensive study for their increased antimicrobial properties. In the current studies, metal and metal-halide nanoparticles were evaluated for their antibacterial efficacy. Silver (Ag), silver bromide (AgBr), silver iodide (AgI), and copper iodide (CuI) nanoparticles significantly reduced bacterial numbers of the Gram-negative Pseudomonas aeruginosa and the Gram-positive Staphylococcus aureus within 24 hours and were more effective against P. aeruginosa. CuI nanoparticles were found to be highly effective, reducing both organisms by >4.43 log 10 within 15 minutes at 60 ppm Cu. CuI nanoparticles formulated with different stabilizers (sodium dodecyl sulfate, SDS; polyvinyl pyrrolidone, PVP) were further tested against representative Gram-positive and Gram-negative bacteria, Mycobacteria, a fungus (Candida albicans ), and a non-enveloped virus (poliovirus). Both nanoparticles caused significant reductions in most of the Gram-negative bacteria within five minutes (>5.09-log10). The Gram-positive bacterial species and C. albicans were more sensitive to the CuI-SDS than the CuI-PVP nanoparticles. In contrast, the acid-fast Mycobacterium smegmatis was more resistant to CuI-SDS than CuI-PVP nanoparticles. Poliovirus was more resistant than the other organisms tested except for Mycobacterium fortuitum, which displayed the greatest resistance to CuI nanoparticles. As an example of a real world antimicrobial application, polymer coatings embedded with various concentrations of CuI nanoparticles were tested for antibacterial efficacy against P. aeruginosa and S. aureus. Polyester-epoxy powder coatings were found to display superior uniformity, stability and antimicrobial properties against both organisms (>4.92 log 10 after six hours at 0.25% Cu). These surfaces were negatively impacted when tested under dry conditions with high organic content. At 0.25% Cu, the antibacterial activity of the powder coatings was not impacted by washing with several commercial cleaners; however, at concentrations of 0.05% Cu, antibacterial activity was reduced by washing with water, WindexRTM , and Pine SolRTM. Ultrasonic cleaning of the coatings appeared to decrease their antimicrobial efficacy. Despite this, CuI nanoparticles were found in all studies to have great potential as a new class of fast-acting, broad-spectrum antimicrobial.

Adsorption of molecular additive onto lead halide perovskite surfaces: A computational study on Lewis base thiophene additive passivation

NASA Astrophysics Data System (ADS)

Zhang, Lei; Yu, Fengxi; Chen, Lihong; Li, Jingfa

2018-06-01

Organic additives, such as the Lewis base thiophene, have been successfully applied to passivate halide perovskite surfaces, improving the stability and properties of perovskite devices based on CH3NH3PbI3. Yet, the detailed nanostructure of the perovskite surface passivated by additives and the mechanisms of such passivation are not well understood. This study presents a nanoscopic view on the interfacial structure of an additive/perovskite interface, consisting of a Lewis base thiophene molecular additive and a lead halide perovskite surface substrate, providing insights on the mechanisms that molecular additives can passivate the halide perovskite surfaces and enhance the perovskite-based device performance. Molecular dynamics study on the interactions between water molecules and the perovskite surfaces passivated by the investigated additive reveal the effectiveness of employing the molecular additives to improve the stability of the halide perovskite materials. The additive/perovskite surface system is further probed via molecular engineering the perovskite surfaces. This study reveals the nanoscopic structure-property relationships of the halide perovskite surface passivated by molecular additives, which helps the fundamental understanding of the surface/interface engineering strategies for the development of halide perovskite based devices.

Determination of the structural phase and octahedral rotation angle in halide perovskites

DOE PAGES

dos Reis, Roberto; Yang, Hao; Ophus, Colin; ...

2018-02-12

A key to the unique combination of electronic and optical properties in halide perovskite materials lies in their rich structural complexity. However, their radiation sensitive nature limits nanoscale structural characterization requiring dose efficient microscopic techniques in order to determine their structures precisely. In this work, we determine the space-group and directly image the Br halide sites of CsPbBr 3, a promising material for optoelectronic applications. Based on the symmetry of high-order Laue zone reflections of convergent-beam electron diffraction, we identify the tetragonal (I4/mcm) structural phase of CsPbBr 3 at cryogenic temperature. Electron ptychography provides a highly sensitive phase contrast measurementmore » of the halide positions under low electron-dose conditions, enabling imaging of the elongated Br sites originating from the out-of-phase octahedral rotation viewed along the [001] direction of I4/mcm persisting at room temperature. The measurement of these features and comparison with simulations yield an octahedral rotation angle of 6.5°(±1.5°). Finally, the approach demonstrated here opens up opportunities for understanding the atomic scale structural phenomena applying advanced characterization tools on a wide range of radiation sensitive halide-based all-inorganic and hybrid organic-inorganic perovskites.« less

Lead Halide Perovskites: Challenges and Opportunities in Advanced Synthesis and Spectroscopy

DOE PAGES

Rosales, Bryan A.; Hanrahan, Michael P.; Boote, Brett W.; ...

2017-03-28

Hybrid lead perovskites containing a mixture of organic and inorganic cations and anions have lead to solar cell devices with better performance and stability than their single halide analogs. Here, 207Pb solid-state nuclear magnetic resonance and single particle photoluminescence spectroscopies show that the structure and composition of mixed-halide and—likely—other hybrid lead perovskites is much more complex than previously thought and is highly dependent on their synthesis. While a majority of reports in the area focus on the construction of photovoltaic devices, this perspective focuses instead on achieving a better understanding of the fundamental chemistry and photophysics of these materials, asmore » this will aid not only in constructing improved devices, but also in generating new uses for these unique materials.« less

Highly luminescent colloidal nanoplates of perovskite cesium lead halide and their oriented assemblies

DOE PAGES

Bekenstein, Yehonadav; Koscher, Brent A.; Eaton, Samuel W.; ...

2015-12-15

Anisotropic colloidal quasi-two-dimensional nanoplates (NPLs) hold great promise as functional materials due to their combination of low dimensional optoelectronic properties and versatility through colloidal synthesis. Recently, lead-halide perovskites have emerged as important optoelectronic materials with excellent efficiencies in photovoltaic and light-emitting applications. Here we report the synthesis of quantum confined all inorganic cesium lead halide nanoplates in the perovskite crystal structure that are also highly luminescent (PLQY 84%). The controllable self-assembly of nanoplates either into stacked columnar phases or crystallographic-oriented thin-sheet structures is demonstrated. Furthermore, the broad accessible emission range, high native quantum yields, and ease of self-assembly make perovskitemore » NPLs an ideal platform for fundamental optoelectronic studies and the investigation of future devices.« less

Environmental Effects on the Photophysics of Organic-Inorganic Halide Perovskites.

PubMed

Galisteo-López, Juan F; Anaya, M; Calvo, M E; Míguez, H

2015-06-18

The photophysical properties of films of organic-inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials.

Environmental Effects on the Photophysics of Organic–Inorganic Halide Perovskites

PubMed Central

2015-01-01

The photophysical properties of films of organic–inorganic lead halide perovskites under different ambient conditions are herein reported. We demonstrate that their luminescent properties are determined by the interplay between photoinduced activation and darkening processes, which strongly depend on the atmosphere surrounding the samples. We have isolated oxygen and moisture as the key elements in each process, activation and darkening, both of which involve the interaction with photogenerated carriers. These findings show that environmental factors play a key role in the performance of lead halide perovskites as efficient luminescent materials. PMID:26266592

Methyl halide fluxes from tropical plants under controlled radiation and temperature regimes

NASA Astrophysics Data System (ADS)

Blei, Emanuel; Yokouchi, Yoko; Saito, Takuya; Nozoe, Susumu

2015-04-01

Methyl halides (CH3Cl, CH3Br, CH3I) contribute significantly to the halogen burden of the atmosphere and have the potential to influence the stratospheric ozone layer through their catalytic effect in the Chapman cycle. As such they have been studied over the years, and many plants and biota have been examined for their potential to act as a source of these gases. One of the potentially largest terrestrial sources identified was tropical vegetation such as tropical ferns and Dipterocarp trees. Most of these studies concentrated on the identification and quantification of such fluxes rather than their characteristics and often the chambers used in these studies were either opaque or only partially transparent to the full solar spectrum. Therefore it is not certain to which degree emissions of methyl halides are innate to the plants and how much they might vary due to radiation or temperature conditions inside the enclosures. In a separate development it had been proposed that UV-radiation could cause live plant materials to be become emitters of methane even under non-anoxic conditions. As methane is chemically very similar to methyl halides and had been proposed to be produced from methyl-groups ubiquitously found in plant cell material there is a relatively good chance that such a production mechanism would also apply to methyl halides. To test whether radiation can affect elevated emissions of methyl halides from plant materials and to distinguish this from temperature effects caused by heat build-up in chambers a set of controlled laboratory chamber enclosures under various radiation and temperature regimes was conducted on four different tropical plant species (Magnolia grandiflora, Cinnamonum camphora, Cyathea lepifera, Angiopteris lygodiifolia), the latter two of which had previously been identified as strong methyl halide emitters. Abscised leaf samples of these species were subjected to radiation treatments such UV-B, UV-A and broad spectrum radiation similar to natural sunlight without the UV-component and the emissions were compared to dark enclosures. Parallel to this temperature effects were studied in dark enclosures as well. The presentation will discuss the outcome of these experiments and what conclusions can be drawn from them.

Designing mixed metal halide ammines for ammonia storage using density functional theory and genetic algorithms.

PubMed

Jensen, Peter Bjerre; Lysgaard, Steen; Quaade, Ulrich J; Vegge, Tejs

2014-09-28

Metal halide ammines have great potential as a future, high-density energy carrier in vehicles. So far known materials, e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, are not suitable for automotive, fuel cell applications, because the release of ammonia is a multi-step reaction, requiring too much heat to be supplied, making the total efficiency lower. Here, we apply density functional theory (DFT) calculations to predict new mixed metal halide ammines with improved storage capacities and the ability to release the stored ammonia in one step, at temperatures suitable for system integration with polymer electrolyte membrane fuel cells (PEMFC). We use genetic algorithms (GAs) to search for materials containing up to three different metals (alkaline-earth, 3d and 4d) and two different halides (Cl, Br and I) - almost 27,000 combinations, and have identified novel mixtures, with significantly improved storage capacities. The size of the search space and the chosen fitness function make it possible to verify that the found candidates are the best possible candidates in the search space, proving that the GA implementation is ideal for this kind of computational materials design, requiring calculations on less than two percent of the candidates to identify the global optimum.

Bulk assembly of organic metal halide nanotubes

DOE PAGES

Lin, Haoran; Zhou, Chenkun; Tian, Yu; ...

2017-10-16

The organic metal halide hybrids welcome a new member with a one-dimensional (1D) tubular structure. Herein we report the synthesis and characterization of a single crystalline bulk assembly of organic metal halide nanotubes, (C 6H 13N 4) 3Pb 2Br 7. In a metal halide nanotube, six face-sharing metal halide dimers (Pb 2Br 9 5–) connect at the corners to form rings that extend in one dimension, of which the inside and outside surfaces are coated with protonated hexamethylenetetramine (HMTA) cations (C 6H 13N 4 +). This unique 1D tubular structure possesses highly localized electronic states with strong quantum confinement, resultingmore » in the formation of self-trapped excitons that give strongly Stokes shifted broadband yellowish-white emission with a photoluminescence quantum efficiency (PLQE) of ~7%. Finally, having realized single crystalline bulk assemblies of two-dimensional (2D) wells, 1D wires, and now 1D tubes using organic metal halide hybrids, our work significantly advances the research on bulk assemblies of quantum-confined materials.« less

Photon Transport in One-Dimensional Incommensurately Epitaxial CsPbX 3 Arrays

DOE PAGES

Wang, Yiping; Sun, Xin; Shivanna, Ravichandran; ...

2016-11-16

One-dimensional nanoscale epitaxial arrays serve as a great model in studying fundamental physics and for emerging applications. With an increasing focus laid on the Cs-based inorganic halide perovskite out of its outstanding material stability, we have applied vapor phase epitaxy to grow well aligned horizontal CsPbX 3 (X: Cl, Br, or I or their mixed) nanowire arrays in large scale on mica substrate. The as-grown nanowire features a triangular prism morphology with typical length ranging from a few tens of micrometers to a few millimeters. Structural analysis reveals that the wire arrays follow the symmetry of mica substrate through incommensuratemore » epitaxy, paving a way for a universally applicable method to grow a broad family of halide perovskite materials. We have studied the unique photon transport in the one-dimensional structure in the all-inorganic Cs-based perovskite wires via temperature dependent and spatially resolved photoluminescence. Furthermore, epitaxy of well oriented wire arrays in halide perovskite would be a promising direction for enabling the circuit-level applications of halide perovskite in high-performance electro-optics and optoelectronics.« less

Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples.

PubMed

Cathcart, Nicole; Kitaev, Vladimir

2016-09-08

A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.

Symmetry Breaking by Surface Blocking: Synthesis of Bimorphic Silver Nanoparticles, Nanoscale Fishes and Apples

NASA Astrophysics Data System (ADS)

Cathcart, Nicole; Kitaev, Vladimir

2016-09-01

A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.

Predicting the thermodynamic stability of double-perovskite halides from density functional theory

DOE PAGES

Han, Dan; Zhang, Tao; Huang, Menglin; ...

2018-05-24

Recently, a series of double-perovskite halide compounds such as Cs 2AgBiCl 6 and Cs 2AgBiBr 6 have attracted intensive interest as promising alternatives to the solar absorber material CH 3NH 3PbI 3 because they are Pb-free and may exhibit enhanced stability. The thermodynamic stability of a number of double-perovskite halides has been predicted based on density functional theory (DFT) calculations of compound formation energies. In this paper, we found that the stability prediction can be dependent on the approximations used for the exchange-correlation functionals, e.g., the DFT calculations using the widely used Perdew, Burke, Ernzerhof (PBE) functional predict that Csmore » 2AgBiBr 6 is thermodynamically unstable against phase-separation into the competing phases such as AgBr, Cs 2AgBr 3, Cs 3Bi 2Br 9, etc., obviously inconsistent with the good stability observed experimentally. The incorrect prediction by the PBE calculation results from its failure to predict the correct ground-state structures of AgBr, AgCl, and CsCl. By contrast, the DFT calculations based on local density approximation, optB86b-vdW, and optB88-vdW functionals predict the ground-state structures of these binary halides correctly. Furthermore, the optB88-vdW functional is found to give the most accurate description of the lattice constants of the double-perovskite halides and their competing phases. Given these two aspects, we suggest that the optB88-vdW functional should be used for predicting thermodynamic stability in the future high-throughput computational material design or the construction of the Materials Genome database for new double-perovskite halides. As a result, using different exchange-correlation functionals has little influence on the dispersion of the conduction and the valence bands near the electronic bandgap; however, the calculated bandgap can be affected indirectly by the optimized lattice constant, which varies for different functionals.« less

Predicting the thermodynamic stability of double-perovskite halides from density functional theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, Dan; Zhang, Tao; Huang, Menglin

Recently, a series of double-perovskite halide compounds such as Cs 2AgBiCl 6 and Cs 2AgBiBr 6 have attracted intensive interest as promising alternatives to the solar absorber material CH 3NH 3PbI 3 because they are Pb-free and may exhibit enhanced stability. The thermodynamic stability of a number of double-perovskite halides has been predicted based on density functional theory (DFT) calculations of compound formation energies. In this paper, we found that the stability prediction can be dependent on the approximations used for the exchange-correlation functionals, e.g., the DFT calculations using the widely used Perdew, Burke, Ernzerhof (PBE) functional predict that Csmore » 2AgBiBr 6 is thermodynamically unstable against phase-separation into the competing phases such as AgBr, Cs 2AgBr 3, Cs 3Bi 2Br 9, etc., obviously inconsistent with the good stability observed experimentally. The incorrect prediction by the PBE calculation results from its failure to predict the correct ground-state structures of AgBr, AgCl, and CsCl. By contrast, the DFT calculations based on local density approximation, optB86b-vdW, and optB88-vdW functionals predict the ground-state structures of these binary halides correctly. Furthermore, the optB88-vdW functional is found to give the most accurate description of the lattice constants of the double-perovskite halides and their competing phases. Given these two aspects, we suggest that the optB88-vdW functional should be used for predicting thermodynamic stability in the future high-throughput computational material design or the construction of the Materials Genome database for new double-perovskite halides. As a result, using different exchange-correlation functionals has little influence on the dispersion of the conduction and the valence bands near the electronic bandgap; however, the calculated bandgap can be affected indirectly by the optimized lattice constant, which varies for different functionals.« less

Persistent dopants and phase segregation in organolead mixed-halide perovskites

DOE PAGES

Rosales, Bryan A.; Men, Long; Cady, Sarah D.; ...

2016-07-25

Organolead mixed-halide perovskites such as CH 3NH 3PbX 3–aX' a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the truemore » chemical speciation and composition of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

Persistent dopants and phase segregation in organolead mixed-halide perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosales, Bryan A.; Men, Long; Cady, Sarah D.

Organolead mixed-halide perovskites such as CH 3NH 3PbX 3–aX' a (X, X' = I, Br, Cl) are interesting semiconductors because of their low cost, high photovoltaic power conversion efficiencies, enhanced moisture stability, and band gap tunability. Using a combination of optical absorption spectroscopy, powder X-ray diffraction (XRD), and, for the first time, 207Pb solid state nuclear magnetic resonance (ssNMR), we probe the extent of alloying and phase segregation in these materials. Because 207Pb ssNMR chemical shifts are highly sensitive to local coordination and electronic structure, and vary linearly with halogen electronegativity and band gap, this technique can provide the truemore » chemical speciation and composition of organolead mixed-halide perovskites. We specifically investigate samples made by three different preparative methods: solution phase synthesis, thermal annealing, and solid phase synthesis. 207Pb ssNMR reveals that nonstoichiometric dopants and semicrystalline phases are prevalent in samples made by solution phase synthesis. We show that these nanodomains are persistent after thermal annealing up to 200 °C. Further, a novel solid phase synthesis that starts from the parent, single-halide perovskites can suppress phase segregation but not the formation of dopants. Our observations are consistent with the presence of miscibility gaps and spontaneous spinodal decomposition of the mixed-halide perovskites at room temperature. This underscores how strongly different synthetic procedures impact the nanostructuring and composition of organolead halide perovskites. In conclusion, better optoelectronic properties and improved device stability and performance may be achieved through careful manipulation of the different phases and nanodomains present in these materials.« less

Ion exchange materials, method of forming ion exchange materials, and methods of treating liquids

DOEpatents

Wertsching, Alan K.; Peterson, Eric S.; Wey, John E.

2007-12-25

The invention includes an ion affinity material having an organic component which is sulfonated and which is chemically bonded to an inorganic substrate component. The invention includes a method of forming a metal binding material. A solid support material comprising surface oxide groups is provided and an organic component having at least one alkyl halide is covalently linked to at least some of the surface oxide groups to form a modified support material. The at least one alkyl halide is subsequently converted into an alkyl sulfonate. The invention further includes a method and system for extracting ions from a liquid. An ion exchange material having a sulfonated alkyl silane component covalently bonded to a metal oxide support material is provided and a liquid is exposed to the ion exchange material.

Chloride, bromide and iodide scintillators with europium doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhuravleva, Mariya; Yang, Kan

A halide scintillator material is disclosed where the halide may comprise chloride, bromide or iodide. The material is single-crystalline and has a composition of the general formula ABX.sub.3 where A is an alkali, B is an alkali earth and X is a halide which general composition was investigated. In particular, crystals of the formula ACa.sub.1-yEu.sub.yI.sub.3 where A=K, Rb and Cs were formed as well as crystals of the formula CsA.sub.1-yEu.sub.yX.sub.3 (where A=Ca, Sr, Ba, or a combination thereof and X=Cl, Br or I or a combination thereof) with divalent Europium doping where 0.ltoreq.y.ltoreq.1, and more particularly Eu doping has beenmore » studied at one to ten mol %. The disclosed scintillator materials are suitable for making scintillation detectors used in applications such as medical imaging and homeland security.« less

Investigation of chemical vapor deposition of garnet films for bubble domain memories

NASA Technical Reports Server (NTRS)

Besser, P. J.; Hamilton, T. N.

1973-01-01

The important process parameters and control required to grow reproducible device quality ferrimagnetic films by chemical vapor deposition (CVD) were studied. The investigation of the critical parameters in the CVD growth process led to the conclusion that the required reproducibility of film properties cannot be achieved with individually controlled separate metal halide sources. Therefore, the CVD growth effort was directed toward replacement of the halide sources with metallic sources with the ultimate goal being the reproducible growth of complex garnet compositions utilizing a single metal alloy source. The characterization of the YGdGaIG films showed that certain characteristics of this material, primarily the low domain wall energy and the large temperature sensitivity, severely limited its potential as a useful material for bubble domain devices. Consequently, at the time of the change from halide to metallic sources, the target film compositions were shifted to more useful materials such as YGdTmGaIG, YEuGaIG and YSmGaIG.

Crossover And MTF Characteristics Of A Tabular-Grain X-Ray Film

NASA Astrophysics Data System (ADS)

Huff, K. E.; Wagner, P. W.

1984-08-01

An orthochromatic x-ray film made with tabular silver halide grains has a significantly higher MTF when exposed with green-emitting intensifying screens than do conventional films with similar sensitometric properties. The primary reason for the improved MTF is a decrease in the amount of crossover exposure, i.e., exposure by light that has crossed the support one or more times. Two well-established sensitometric procedures for measuring crossover have been compared. One produces results accurate enough for calculations of MTF relationships. Calculated MTF relationships for tabulargrain and conventional films are compared with measured values.

Paintings, photographs, and computer graphics are calculated appearances

NASA Astrophysics Data System (ADS)

McCann, John

2012-03-01

Painters reproduce the appearances they see, or visualize. The entire human visual system is the first part of that process, providing extensive spatial processing. Painters have used spatial techniques since the Renaissance to render HDR scenes. Silver halide photography responds to the light falling on single film pixels. Film can only mimic the retinal response of the cones at the start of the visual process. Film cannot mimic the spatial processing in humans. Digital image processing can. This talk studies three dramatic visual illusions and uses the spatial mechanisms found in human vision to interpret their appearances.

Fabrication of Low-Loss Halide Glass Fibers.

DTIC Science & Technology

1985-09-01

chalcogenides, have some merit. Well known, also are the polycrystalline halide materials such as KRS-5, TlBr , *TlI and AgCl and their single...tension of the melt zone is high enough to *" eliminate sagging in the fibers. Using this technique, ( TlBr )I (KRS-5), TlBr , CuCl, AgCl, and AgBr have

Ultra-low temperature curable nano-silver conductive adhesive for piezoelectric composite material

NASA Astrophysics Data System (ADS)

Yan, Chao; Liao, Qingwei; Zhou, Xingli; Wang, Likun; Zhong, Chao; Zhang, Di

2018-01-01

Limited by the low thermal resistance of composite material, ultra-low temperature curable conductive silver adhesive with curing temperature less than 100 °C needed urgently for the surface conduction treatment of piezoelectric composite material. An ultra-low temperature curable nano-silver conductive adhesive with high adhesion strength for the applications of piezoelectric composite material was investigated. The crystal structure of cured adhesive, SEM/EDS analysis, thermal analysis, adhesive properties and conductive properties of different content of nano-silver filler or micron-silver doping samples were studied. The results show that with 60 wt.% nano-silver filler the ultra-low temperature curable conductive silver adhesive had the relatively good conductivity as volume resistivity of 2.37 × 10-4 Ω cm, and good adhesion strength of 5.13 MPa. Minor micron-doping (below 15 wt.%) could improve conductivity, but would decrease other properties. The ultra-low temperature curable nano-silver conductive adhesive could successfully applied to piezoelectric composite material.

Molten salts in Nuclear Reactors (Bibliography); LES SELS FONDUS DANS LES REACTEURS NUCLEAIRES (BIBLIOGRAPHIE)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dirian, J.; Saint-James, R.

1959-01-01

A collection is presented of references dealing with the physicochemical studies of fused salts, in partictular the alkali and alkali earth halides. Numerous binary, ternary and quaternary systems of these halides with those of uranium and thoriuna are examined, and the physical properties, density, viscosity, and vapor pressure going from the halides to the mixtures are also considered. References relating to the corrosion of materials by these salts are included and the treatment of the salts with a view to recovery after irradiation in a nuclear reactor is discussed. (auth)

Color holography for museums: bringing the artifacts back to the people

NASA Astrophysics Data System (ADS)

Bjelkhagen, Hans I.; Osanlou, Ardie

2011-02-01

Color display holography, which is the most accurate imaging technology known to science, has been used to produce holographic images for display of artifacts in museums. This article presents the 'Bringing the Artifacts back to the people' project. Holograms of twelve different artifacts were recorded using the single-beam Denisyuk color reflection hologram technique. 'White' laser light was produced from three combined cw RGB lasers: a red krypton-ion laser, a green frequency-doubled Nd-YAG laser, and an argon-ion laser. Panchromatic ultra-fine-grain silver halide materials were used for the recording of the holograms. During 2009 the artifacts were brought to St Asaph in Wales at the Centre for Modern Optics, to undergo holographic recording. One of the recorded artifacts included a 14,000-year-old decorated horse jaw bone from the ice age, which is kept at British Museum in London. The recorded color holograms of this object and others have been arranged in a touring exhibition, the 'Virtual Artifacts Exhibition.' During 2010- 2011, this will be installed in a number of local museums in North Wales and surrounding areas.

Feature issue introduction: halide perovskites for optoelectronics.

PubMed

White, Thomas P; Deleporte, Emmanuelle; Sum, Tze-Chien

2018-01-22

This joint Optics Express and Optical Materials Express feature issue presents a collection of nine papers on the topic of halide perovskites for optoelectronics. Perovskite materials have attracted significant attention over the past four years, initially for their outstanding performance in thin film solar cells, but more recently for applications in light-emitting devices (LEDs and lasers), photodetectors and nonlinear optics. At the same time, there is still much more to learn about the fundamental properties of these materials, and how these depend on composition, processing, and exposure to the environment. This feature issue provides a snapshot of some of the latest research in this rapidly-evolving multidisciplinary field.

Size-Dependent Photon Emission from Organometal Halide Perovskite Nanocrystals Embedded in an Organic Matrix

PubMed Central

2015-01-01

In recent years, organometal halide perovskite materials have attracted significant research interest in the field of optoelectronics. Here, we introduce a simple and low-temperature route for the formation of self-assembled perovskite nanocrystals in a solid organic matrix. We demonstrate that the size and photoluminescence peak of the perovskite nanocrystals can be tuned by varying the concentration of perovskite in the matrix material. The physical origin of the blue shift of the perovskite nanocrystals’ emission compared to its bulk phase is also discussed. PMID:25949773

Rationalizing the light-induced phase separation of mixed halide organic-inorganic perovskites.

PubMed

Draguta, Sergiu; Sharia, Onise; Yoon, Seog Joon; Brennan, Michael C; Morozov, Yurii V; Manser, Joseph S; Kamat, Prashant V; Schneider, William F; Kuno, Masaru

2017-08-04

Mixed halide hybrid perovskites, CH 3 NH 3 Pb(I 1-x Br x ) 3 , represent good candidates for low-cost, high efficiency photovoltaic, and light-emitting devices. Their band gaps can be tuned from 1.6 to 2.3 eV, by changing the halide anion identity. Unfortunately, mixed halide perovskites undergo phase separation under illumination. This leads to iodide- and bromide-rich domains along with corresponding changes to the material's optical/electrical response. Here, using combined spectroscopic measurements and theoretical modeling, we quantitatively rationalize all microscopic processes that occur during phase separation. Our model suggests that the driving force behind phase separation is the bandgap reduction of iodide-rich phases. It additionally explains observed non-linear intensity dependencies, as well as self-limited growth of iodide-rich domains. Most importantly, our model reveals that mixed halide perovskites can be stabilized against phase separation by deliberately engineering carrier diffusion lengths and injected carrier densities.Mixed halide hybrid perovskites possess tunable band gaps, however, under illumination they undergo phase separation. Using spectroscopic measurements and theoretical modelling, Draguta and Sharia et al. quantitatively rationalize the microscopic processes that occur during phase separation.

Silver Recycling in the United States in 2000

USGS Publications Warehouse

Hilliard, Henry E.

2003-01-01

In 2000, the global silver supply deficit (the difference between mine and scrap supply and silver demand) was more than 3,000 metric tons. U.S. silver demand for photographic applications alone was nearly equal to annual U.S. silver production. Until 1968, the U.S. silver deficit was filled by withdrawals from the U.S. Treasury reserves. In 2000, the deficit was filled by destocking, imports, and recycling. Photographic wastes, spent catalysts, and electronic scrap are the major sources of materials for silver recycling. Nearly 1,800 tons of silver contained in these materials were available for recycling in 2000. Other recyclable silver-bearing materials include dental alloys, jewelry, and silverware. In 2000, an estimated 1,700 tons of silver were recovered from secondary sources in the United States. The U.S. recycling efficiency for old scrap was calculated to have been 97 percent in 2000; the recycling rate was estimated to be 32 percent.

Silver recycling in the United States in 2000

USGS Publications Warehouse

Hilliard, Henry E.

2003-01-01

In 2000, the global silver supply deficit (the difference between mine and scrap supply and silver demand) was more than 3,000 metric tons. U.S. silver demand for photographic applications alone was nearly equal to annual U.S. silver production. Until 1968, the U.S. silver deficit was filled by withdrawals from the U.S. Treasury reserves. In 2000, the deficit was filled by destocking, imports, and recycling. Photographic wastes, spent catalysts, and electronic scrap are the major sources of materials for silver recycling. Nearly 1,800 metric tons of silver contained in these materials were available for recycling in 2000. Other recyclable silver-bearing materials include dental alloys, jewelry, and silverware. In 2000, an estimated 1,700 tons of silver were recovered from secondary sources in the United States. The U.S. recycling efficiency for old scrap was calculated to have been 97 percent in 2000; the recycling rate was estimated to be 32 percent.

Inorganic rechargeable non-aqueous cell

DOEpatents

Bowden, William L.; Dey, Arabinda N.

1985-05-07

A totally inorganic non-aqueous rechargeable cell having an alkali or alkaline earth metal anode such as of lithium, a sulfur dioxide containing electrolyte and a discharging metal halide cathode, such as of CuCl.sub.2, CuBr.sub.2 and the like with said metal halide being substantially totally insoluble in SO.sub.2 and admixed with a conductive carbon material.

Fire extinguishant materials

NASA Technical Reports Server (NTRS)

Altman, R. L.; Mayer, L. A.; Ling, A. C. (Inventor)

1983-01-01

Fire extinguishant composition comprising a mixture of a finely divided aluminum compound and alkali metal, stannous or plumbous halide is provided. Aluminum compound may be aluminum hydroxide, alumina or boehmite but preferably it is an alkali metal dawsonite. The metal halide may be an alkali metal, e.g. potassium iodide, bromide or chloride or stannous or plumbous iodide, bromide or chloride. Potassium iodide is preferred.

Lasing in robust cesium lead halide perovskite nanowires

PubMed Central

Eaton, Samuel W.; Lai, Minliang; Gibson, Natalie A.; Wong, Andrew B.; Dou, Letian; Ma, Jie; Wang, Lin-Wang; Leone, Stephen R.; Yang, Peidong

2016-01-01

The rapidly growing field of nanoscale lasers can be advanced through the discovery of new, tunable light sources. The emission wavelength tunability demonstrated in perovskite materials is an attractive property for nanoscale lasers. Whereas organic–inorganic lead halide perovskite materials are known for their instability, cesium lead halides offer a robust alternative without sacrificing emission tunability or ease of synthesis. Here, we report the low-temperature, solution-phase growth of cesium lead halide nanowires exhibiting low-threshold lasing and high stability. The as-grown nanowires are single crystalline with well-formed facets, and act as high-quality laser cavities. The nanowires display excellent stability while stored and handled under ambient conditions over the course of weeks. Upon optical excitation, Fabry–Pérot lasing occurs in CsPbBr3 nanowires with an onset of 5 μJ cm−2 with the nanowire cavity displaying a maximum quality factor of 1,009 ± 5. Lasing under constant, pulsed excitation can be maintained for over 1 h, the equivalent of 109 excitation cycles, and lasing persists upon exposure to ambient atmosphere. Wavelength tunability in the green and blue regions of the spectrum in conjunction with excellent stability makes these nanowire lasers attractive for device fabrication. PMID:26862172

Surface properties of lead-free halide double perovskites: Possible visible-light photo-catalysts for water splitting

NASA Astrophysics Data System (ADS)

Volonakis, George; Giustino, Feliciano

2018-06-01

Halide double perovskites based on combinations of monovalent and trivalent cations have been proposed as promising lead-free alternatives to lead halide perovskites. Among the newly synthesized compounds Cs2BiAgCl6, Cs2BiAgBr6, Cs2SbAgCl6, and Cs2InAgCl6, some exhibit bandgaps in the visible range and all have low carrier effective masses; therefore, these materials constitute potential candidates for various opto-electronic applications. Here, we use first-principles calculations to investigate the electronic properties of the surfaces of these four compounds and determine, for the first time, their ionization potential and electron affinity. We find that the double perovskites Cs2BiAgCl6 and Cs2BiAgBr6 are potentially promising materials for photo-catalytic water splitting, while Cs2InAgCl6 and Cs2SbAgCl6 would require controlling their surface termination to obtain energy levels appropriate for water splitting. The energy of the halogen p orbitals is found to control the conduction band level; therefore, we propose that mixed halides could be used to fine-tune the electronic affinity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

dos Reis, Roberto; Yang, Hao; Ophus, Colin

A key to the unique combination of electronic and optical properties in halide perovskite materials lies in their rich structural complexity. However, their radiation sensitive nature limits nanoscale structural characterization requiring dose efficient microscopic techniques in order to determine their structures precisely. In this work, we determine the space-group and directly image the Br halide sites of CsPbBr 3, a promising material for optoelectronic applications. Based on the symmetry of high-order Laue zone reflections of convergent-beam electron diffraction, we identify the tetragonal (I4/mcm) structural phase of CsPbBr 3 at cryogenic temperature. Electron ptychography provides a highly sensitive phase contrast measurementmore » of the halide positions under low electron-dose conditions, enabling imaging of the elongated Br sites originating from the out-of-phase octahedral rotation viewed along the [001] direction of I4/mcm persisting at room temperature. The measurement of these features and comparison with simulations yield an octahedral rotation angle of 6.5°(±1.5°). Finally, the approach demonstrated here opens up opportunities for understanding the atomic scale structural phenomena applying advanced characterization tools on a wide range of radiation sensitive halide-based all-inorganic and hybrid organic-inorganic perovskites.« less

Advances in the growth of alkaline-earth halide single crystals for scintillator detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boatner, Lynn A; Ramey, Joanne Oxendine; Kolopus, James A

2014-01-01

Alkaline-earth scintillators such as strontium iodide and other alkaline-earth halides activated with divalent europium represent some of the most efficient and highest energy resolution scintillators for use as gamma-ray detectors in a wide range of applications. These applications include the areas of nuclear nonproliferation, homeland security, the detection of undeclared nuclear material, nuclear physics and materials science, medical diagnostics, space physics, high energy physics, and radiation monitoring systems for first responders, police, and fire/rescue personnel. Recent advances in the growth of large single crystals of these scintillator materials hold the promise of higher crystal yields and significantly lower detector productionmore » costs. In the present work, we describe new processing protocols that, when combined with our molten salt filtration methods, have led to advances in achieving a significant reduction of cracking effects during the growth of single crystals of SrI2:Eu2+. In particular, we have found that extended pumping on the molten crystal-growth charge under vacuum for time periods extending up to 48 hours is generally beneficial in compensating for variations in the alkaline-earth halide purity and stoichiometry of the materials as initially supplied by commercial sources. These melt-pumping and processing techniques are now being applied to the purification of CaI2:Eu2+ and some mixed-anion europium-doped alkaline-earth halides prior to single-crystal growth by means of the vertical Bridgman technique. The results of initial studies of the effects of aliovalent doping of SrI2:Eu2+ on the scintillation characteristics of this material are also described.« less

Assessment of antimicrobial effects of food contact materials containing silver on growth of Salmonella Typhimurium.

PubMed

Williams, Katherine; Valencia, Luis; Gokulan, Kuppan; Trbojevich, Raul; Khare, Sangeeta

2017-02-01

Food contact materials containing antibacterial properties are progressively appearing in the market. Items intended to provide antimicrobial effects such as increased shelf life and food safety are incorporating silver materials during the manufacture of such products. This study examined the total silver content, release capacity, and antibacterial activity of three different silver-containing food contact materials: plastic food storage containers, a plastic cutting board, and food wrapping paper. Silver content and release were determined by Inductively Coupled Plasma Mass Spectrometry, and the results showed that, although the amount of silver in each product was similar, migration varied considerably with kind of material and simulant choice. Antimicrobial effect was tested by measuring the growth of Salmonella Typhimurium during or after exposure to the different food contact materials. The results showed that the food storage containers and wrapping paper delayed the growth of S. Typhimurium under certain conditions, but that these effects were short-lived. The strain of S. Typhimurium used in this study was found to be negative for the presence of tested silver resistance genes. The results of this study suggest that a thorough investigation should be required to show/claim the efficacy of silver-containing food contact materials for food safety purposes. Published by Elsevier Ltd.

Method and etchant to join ag-clad BSSCO superconducting tape

DOEpatents

Balachandran, Uthamalingam; Iyer, Anand N.; Huang, Jiann Yuan

1999-01-01

A method of removing a silver cladding from high temperature superconducting material clad in silver (HTS) is disclosed. The silver clad HTS is contacted with an aqueous solution of HNO.sub.3 followed by an aqueous solution of NH.sub.4 OH and H.sub.2 O.sub.2 for a time sufficient to remove the silver cladding from the superconducting material without adversely affecting the superconducting properties of the superconducting material. A portion of the silver cladding may be masked with a material chemically impervious to HNO.sub.3 and to a combination of NH.sub.4 OH and H.sub.2 O.sub.2 to preserve the Ag coating. A silver clad superconductor is disclosed, made in accordance with the method discussed.

Electrochemistry and Spectroelectrochemistry of Lead Halide Perovskite Films: Materials Science Aspects and Boundary Conditions.

PubMed

Samu, Gergely F; Scheidt, Rebecca A; Kamat, Prashant V; Janáky, Csaba

2018-02-13

The unique optoelectronic properties of lead halide perovskites have triggered a new wave of excitement in materials chemistry during the past five years. Electrochemistry, spectroelectrochemistry, and photoelectrochemistry could be viable tools both for analyzing the optoelectronic features of these materials and for assembling them into hybrid architectures (e.g., solar cells). At the same time, the instability of these materials limits the pool of solvents and electrolytes that can be employed in such experiments. The focus of our study is to establish a stability window for electrochemical tests for all-inorganic CsPbBr 3 and hybrid organic-inorganic MAPbI 3 perovskites. In addition, we aimed to understand the reduction and oxidation events that occur and to assess the damage done during these processes at extreme electrochemical conditions. In this vein, we demonstrated the chemical, structural, and morphological changes of the films in both reductive and oxidative environments. Taking all these results together as a whole, we propose a set of boundary conditions and protocols for how electrochemical experiments with lead halide perovskites should be carried out and interpreted. The presented results will contribute to the understanding of the electrochemical response of these materials and lead to a standardization of results in the literature so that comparisons can more easily be made.

PROCESS OF PRODUCING REFRACTORY URANIUM OXIDE ARTICLES

DOEpatents

Hamilton, N.E.

1957-12-01

A method is presented for fabricating uranium oxide into a shaped refractory article by introducing a uranium halide fluxing reagent into the uranium oxide, and then mixing and compressing the materials into a shaped composite mass. The shaped mass of uranium oxide and uranium halide is then fired at an elevated temperature so as to form a refractory sintered article. It was found in the present invention that the introduction of a uraninm halide fluxing agent afforded a fluxing action with the uranium oxide particles and that excellent cohesion between these oxide particles was obtained. Approximately 90% of uranium dioxide and 10% of uranium tetrafluoride represent a preferred composition.

High-Efficiency Flexible Solar Cells Based on Organometal Halide Perovskites.

PubMed

Wang, Yuming; Bai, Sai; Cheng, Lu; Wang, Nana; Wang, Jianpu; Gao, Feng; Huang, Wei

2016-06-01

Flexible and light-weight solar cells are important because they not only supply power to wearable and portable devices, but also reduce the transportation and installation cost of solar panels. High-efficiency organometal halide perovskite solar cells can be fabricated by a low-temperature solution process, and hence are promising for flexible-solar-cell applications. Here, the development of perovskite solar cells is briefly discussed, followed by the merits of organometal halide perovskites as promising candidates as high-efficiency, flexible, and light-weight photovoltaic materials. Afterward, recent developments of flexible solar cells based on perovskites are reviewed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abnormal crystal growth in CH 3NH 3PbI 3-xCl x using a multi-cycle solution coating process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Qingfeng; Yuan, Yongbo; Shao, Yuchuan

2015-06-23

Recently, the efficiency of organolead trihalide perovskite solar cells has improved greatly because of improved material qualities with longer carrier diffusion lengths. Mixing chlorine in the precursor for mixed halide films has been reported to dramatically enhance the diffusion lengths of mixed halide perovskite films, mainly as a result of a much longer carrier recombination lifetime. Here we report that adding Cl containing precursor for mixed halide perovskite formation can induce the abnormal grain growth behavior that yields well-oriented grains accompanied by the appearance of some very large size grains. The abnormal grain growth becomes prominent only after multi-cycle coatingmore » of MAI : MACl blend precursor. The large grain size is found mainly to contribute to a longer carrier charge recombination lifetime, and thus increases the device efficiency to 18.9%, but without significantly impacting the carrier transport property. As a result, the strong correlation identified between material process and morphology provides guidelines for future material optimization and device efficiency enhancement.« less

Switchable S = 1/2 and J = 1/2 Rashba bands in ferroelectric halide perovskites

PubMed Central

Kim, Minsung; Im, Jino; Freeman, Arthur J.; Ihm, Jisoon; Jin, Hosub

2014-01-01

The Rashba effect is spin degeneracy lift originated from spin–orbit coupling under inversion symmetry breaking and has been intensively studied for spintronics applications. However, easily implementable methods and corresponding materials for directional controls of Rashba splitting are still lacking. Here, we propose organic–inorganic hybrid metal halide perovskites as 3D Rashba systems driven by bulk ferroelectricity. In these materials, it is shown that the helical direction of the angular momentum texture in the Rashba band can be controlled by external electric fields via ferroelectric switching. Our tight-binding analysis and first-principles calculations indicate that and Rashba bands directly coupled to ferroelectric polarization emerge at the valence and conduction band edges, respectively. The coexistence of two contrasting Rashba bands having different compositions of the spin and orbital angular momentum is a distinctive feature of these materials. With recent experimental evidence for the ferroelectric response, the halide perovskites will be, to our knowledge, the first practical realization of the ferroelectric-coupled Rashba effect, suggesting novel applications to spintronic devices. PMID:24785294

Lead-free Halide Perovskites via Functionality-directed Materials Screening

NASA Astrophysics Data System (ADS)

Zhang, Lijun; Yang, Dongwen; Lv, Jian; Zhao, Xingang; Yang, Ji-Hui; Yu, Liping; Wei, Su-Huai; Zunger, Alex

Hybrid organic-inorganic halide perovskites with the prototype material of CH3NH3PbI3 have recently attracted much interest as low-cost and high-performance photovoltaic absorbers but one would like to improve their stability and get rid of toxic Pb. We used photovoltaic-functionality-directed materials screening approach to rationally design via first-principles DFT calculations Pb-free halide perovskites. Screening criteria involve thermodynamic and crystallographic stability, as well as solar band gaps, light carrier effective masses, exciton binding, etc. We considered both single atomic substitutions in AMX3 normal perovskites (altering chemical constituents of A, M and X individually) as well as double substitution of 2M into B+C in A2BCX6 double-perovskites. Chemical trends in phase stabilities and optoelectronic properties are discussed with some promising cases exhibiting solar cell efficiencies comparable to that of CH3NH3PbI3. L.Z. founded by Recruitment Program of Global Youth Experts and National Key Research and Development Program of China, and A.Z. by DOE EERE Sun Shot of USA.

Recent progress in efficient hybrid lead halide perovskite solar cells

PubMed Central

Cui, Jin; Yuan, Huailiang; Li, Junpeng; Xu, Xiaobao; Shen, Yan; Lin, Hong; Wang, Mingkui

2015-01-01

The efficiency of perovskite solar cells (PSCs) has been improved from 9.7 to 19.3%, with the highest value of 20.1% achieved in 2014. Such a high photovoltaic performance can be attributed to optically high absorption characteristics and balanced charge transport properties with long diffusion lengths of the hybrid lead halide perovskite materials. In this review, some fundamental details of hybrid lead iodide perovskite materials, various fabrication techniques and device structures are described, aiming for a better understanding of these materials and thus highly efficient PSC devices. In addition, some advantages and open issues are discussed here to outline the prospects and challenges of using perovskites in commercial photovoltaic devices. PMID:27877815

Silver(I) Binding Properties of Organic Soil Materials Are Different from Those of Isolated Humic Substances.

PubMed

B Kleja, Dan; Nakata, Satomi; Persson, Ingmar; Gustafsson, Jon Petter

2016-07-19

The solubility of silver(I) in many soils is controlled by complexation reactions with organic matter. In this work we have compared the ability of isolated humic and fulvic acids to bind silver(I) with that of mor and peat materials. One new data set for Suwannee River Fulvic Acid was produced, which was consistent with published data sets for isolated fulvic and humic acids. The ability of soil materials to bind silver(I) was studied as a function of pH in the range 2.5-5.0, at a wide range of silver(I)-to-soil ratios (10(-4.2) - 10(-1.9) mol kg(-1)). By calibrating the Stockholm Humic Model on the humic and fulvic acids data sets, we showed that binding of silver(I) to both types of soil materials was much stronger (up to 2 orders of magnitude) than predicted from the silver(I) binding properties of the isolated humic materials. Thus, the approach taken for many other metals, that is, to model solubility in soils by using metal and proton binding parameters derived from isolated humic and fulvic acids, cannot be used for silver(I). One possible explanation for the discrepancy could be that silver(I) predominately interacted with various biomolecules in the soil samples, instead of humic- and fulvic-acid type materials.

Study of space charge layer in silver bromide microcrystals by means of ultraviolet photoelectron spectroscopy

NASA Astrophysics Data System (ADS)

Tani, Tadaaki; Inami, Yoshiyasu

2000-09-01

Ultraviolet photoelectron spectroscopy has been successfully used to measure the heights of the tops of the valence bands of the surfaces of AgBr layers on Ag substrates for the verification of the space charge layer model. According to this model, the positive space charge layer (composed of negative charges with excess negative kink sites on the surface and corresponding positive charges with interstitial silver ions in the interior) is formed in silver halides, causing the difference in the electronic energy levels between their surface and interior. The depression of the positive space charge layer of AgBr caused by such adsorbates as photographic stabilizers and antifoggants was estimated from the decrease in the ionic conductivity of cubic AgBr microcrystals by the adsorbates. It was confirmed by the decrease in the heights of the tops of the valence bands of the surfaces of AgBr layers caused by the adsorbates in the presence of thin gelatin membranes on their surfaces. This result provided the explanation for the fact that the adsorbates increased the number of the microcrystals which formed latent image centers on the surface and decreased the number of the microcrystals, which formed latent image centers in the interior.

Graphical evaluation of complexometric titration curves.

PubMed

Guinon, J L

1985-04-01

A graphical method, based on logarithmic concentration diagrams, for construction, without any calculations, of complexometric titration curves is examined. The titration curves obtained for different kinds of unidentate, bidentate and quadridentate ligands clearly show why only chelating ligands are usually used in titrimetric analysis. The method has also been applied to two practical cases where unidentate ligands are used: (a) the complexometric determination of mercury(II) with halides and (b) the determination of cyanide with silver, which involves both a complexation and a precipitation system; for this purpose construction of the diagrams for the HgCl(2)/HgCl(+)/Hg(2+) and Ag(CN)(2)(-)/AgCN/CN(-) systems is considered in detail.

Development of tapered silver-halide fiber tips for a scanning near-field microscope operating in the middle infrared

NASA Astrophysics Data System (ADS)

Platkov, Max; Tsun, Alexander; Nagli, Lev; Katzir, Abraham

2006-12-01

We have constructed a scanning near-field infrared microscope (SNIM) which was based on a AgClBr fiber probe whose end was etched to form an aperture of a subwavelength diameter. A detailed study of the mechanical properties of a vibrating AgClBr probe was required for proper operation of the SNIM system. We have demonstrated that the system can be used for imaging and for topographic mapping of samples with a subwavelength resolution in the middle infrared. Such a SNIM will be a powerful tool for the study of microelectronic components or subcellular structures in biological cells.

Defect-induced band-edge reconstruction of a bismuth-halide double perovskite for visible-light absorption

DOE PAGES

Slavney, Adam H.; Leppert, Linn; Bartesaghi, Davide; ...

2017-03-29

In this study, halide double perovskites have recently been developed as less toxic analogs of the lead perovskite solar-cell absorbers APbX 3 (A = monovalent cation; X = Br or I). However, all known halide double perovskites have large bandgaps that afford weak visible-light absorption. The first halide double perovskite evaluated as an absorber, Cs 2AgBiBr 6 (1), has a bandgap of 1.95 eV. Here, we show that dilute alloying decreases 1’s bandgap by ca. 0.5 eV. Importantly, time-resolved photoconductivity measurements reveal long-lived carriers with microsecond lifetimes in the alloyed material, which is very promising for photovoltaic applications. The alloyedmore » perovskite described herein is the first double perovskite to show comparable bandgap energy and carrier lifetime to those of (CH 3NH 3)PbI 3. By describing how energy- and symmetry-matched impurity orbitals, at low concentrations, dramatically alter 1’s band edges, we open a potential pathway for the large and diverse family of halide double perovskites to compete with APbX 3 absorbers.« less

Method and etchant to join Ag-clad BSSCO superconducting tape

DOEpatents

Balachandran, U.; Iyer, A.N.; Huang, J.Y.

1999-03-16

A method of removing a silver cladding from high temperature superconducting material clad in silver (HTS) is disclosed. The silver clad HTS is contacted with an aqueous solution of HNO{sub 3} followed by an aqueous solution of NH{sub 4}OH and H{sub 2}O{sub 2} for a time sufficient to remove the silver cladding from the superconducting material without adversely affecting the superconducting properties of the superconducting material. A portion of the silver cladding may be masked with a material chemically impervious to HNO{sub 3} and to a combination of NH{sub 4}OH and H{sub 2}O{sub 2} to preserve the Ag coating. A silver clad superconductor is disclosed, made in accordance with the method discussed. 3 figs.

Assessment of Silver Based Disinfection Technology for CEV and Future US Spacecraft

NASA Technical Reports Server (NTRS)

Callahan, Michael R.; Adam, Niklas M.; Roberts, Michael S.; Garland, Jay L.; Sager, John C.; Pickering, Karen D.

2007-01-01

Silver biocide offers a potential advantage over iodine, the current state-of-the-art in US spacecraft disinfection technology, in that silver can be safely consumed by the crew. As such, silver may reduce the overall complexity and mass of future spacecraft potable water systems, particularly those used to support long duration missions. A primary technology gap identified for the use of silver biocide is one of material compatibility. Wetted materials of construction are required to be selected such that silver ion concentrations can be maintained at biocidally effective levels. Preliminary data on silver biocide depletion rates in heritage spacecraft potable water system wetted-materials of construction has been gathered as part of a multi-phase test project aimed at the characterization of silver based biocide technology through: development of preferred materials lists, investigation of silver biocide forms and delivery methods, down-selection of silver biocide technologies, and integrated testing. A 10% - 20% loss in silver ion concentration per day was observed for acid passivated Nitronic 40 tubing with surface area to volume (S/V) ratios of approximately 4.59 cm-1. The Nitronic 40 tubes were tested both with and without biocide pretreatment. Silver biocide depletion was also observed at approximately 0.1% per day for the first 35 days of exposure to acid passivated Inconel 718 coupon, S/V of approximately 0.14 cm-1. Surface analysis by scanning election microscopy (SEM) suggested deposition of silver metal on both test materials. SEM analysis also provided evidence of potential variability in the passivation process for tube configuration of the Nitronic 40 test apparatus. These preliminary results are presented and discussed herein, along with the current project status.

Metal-halide mixtures for latent heat energy storage

NASA Astrophysics Data System (ADS)

Chen, K.; Manvi, R.

Some candidates for alkali metal and alkali halide mixtures suitable for thermal energy storage at temperatures 600 C are identified. A solar thermal system application which offer advantages such as precipitation of salt crystals away from heat transfer surfaces, increased thermal conductivity of phase change materials, corrosion inhibition, and a constant monotectic temperature, independent of mixture concentrations. By using the lighters, metal rich phase as a heat transfer medium and the denser, salt rich phase as a phase change material for latent heat storage, undesirable solidification on the heat transfer surface may be prevented, is presented.

Resonant halide perovskite nanoparticles

NASA Astrophysics Data System (ADS)

Tiguntseva, Ekaterina Y.; Ishteev, Arthur R.; Komissarenko, Filipp E.; Zuev, Dmitry A.; Ushakova, Elena V.; Milichko, Valentin A.; Nesterov-Mueller, Alexander; Makarov, Sergey V.; Zakhidov, Anvar A.

2017-09-01

The hybrid halide perovskites is a prospective material for fabrication of cost-effective optical devices. Unique perovskites properties are used for solar cells and different photonic applications. Recently, perovskite-based nanophotonics has emerged. Here, we consider perovskite like a high-refractive index dielectric material, which can be considered to be a basis for nanoparticles fabrication with Mie resonances. As a result, we fabricate and study resonant perovskite nanoparticles with different sizes. We reveal, that spherical nanoparticles show enhanced photoluminescence signal. The achieved results lay a cornerstone in the field of novel types of organic-inorganic nanophotonics devices with optical properties improved by Mie resonances.

Metal-halide mixtures for latent heat energy storage

NASA Technical Reports Server (NTRS)

Chen, K.; Manvi, R.

1981-01-01

Some candidates for alkali metal and alkali halide mixtures suitable for thermal energy storage at temperatures 600 C are identified. A solar thermal system application which offer advantages such as precipitation of salt crystals away from heat transfer surfaces, increased thermal conductivity of phase change materials, corrosion inhibition, and a constant monotectic temperature, independent of mixture concentrations. By using the lighters, metal rich phase as a heat transfer medium and the denser, salt rich phase as a phase change material for latent heat storage, undesirable solidification on the heat transfer surface may be prevented, is presented.

Structural and thermodynamic aspects of organic-inorganic mixed halide (CH3NH3PbI3-xBrx) perovskite

NASA Astrophysics Data System (ADS)

Singh, Rajan Kumar; Kumar, Ranveer; Jain, Neha; Singh, Jai; Mishra, S. K.

2018-05-01

Mixed Bromine and iodine lead halide perovskite CH3NH3PbI3-xBrx have been synthesized by solution phase method using CH3NH3I and PbBr2 precursors in ambient conditions. X-ray diffraction indicates the formation of cubic perovskite at room temperature with space group of Pm3m. The mixed perovskite improved crystallanity and grain contour which may significant improve photovoltaic performance of perovskite devices. Thermodynamic behavior of such type of material also indicates energy absorption nature of materials.

Electrochemical quantification of iodide ions in synthetic urine using silver nanoparticles: a proof-of-concept.

PubMed

Toh, Her Shuang; Tschulik, Kristina; Batchelor-McAuley, Christopher; Compton, Richard G

2014-08-21

Typical urinary iodide concentrations range from 0.3 μM to 6.0 μM. The conventional analytical method is based on the Sandell-Kolthoff reaction. It involves the toxic reagent, arsenic acid, and a waiting time of 30 minutes for the iodide ions to reduce the cerium(iv) ions. In the presented work, an alternative fast electrochemical method based on a silver nanoparticle modified electrode is proposed. Cyclic voltammetry was performed with a freshly modified electrode in presence of iodide ions and the voltammetric peaks corresponding to the oxidation of silver to silver iodide and the reverse reaction were recorded. The peak height of the reduction signal of silver iodide was used to plot a calibration line for the iodide ions. Two calibration plots for the iodide ions were obtained, one in 0.1 M sodium nitrate (a chloride-ion free environment to circumvent any interference from the other halides) and another in synthetic urine (which contains 0.2 M KCl). In both of the calibration plots, linear relationships were found between the reduction peak height and the iodide ion concentration of 0.3 μM to 6.0 μM. A slope of 1.46 × 10(-2) A M(-1) and a R(2) value of 0.999 were obtained for the iodide detection in sodium nitrate. For the synthetic urine experiments, a slope of 3.58 × 10(-3) A M(-1) and a R(2) value of 0.942 were measured. A robust iodide sensor with the potential to be developed into a point-of-care system has been validated.

Local polar fluctuations in lead halide perovskite crystals

DOE PAGES

Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.; ...

2017-03-28

Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH 3NH 3PbBr 3) and all-inorganic (CsPbBr 3) lead-halide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. Furthermore, MD simulations indicatemore » that head-to-head Cs motion coupled to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr 3.« less

How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

NASA Astrophysics Data System (ADS)

Kam, K.; Lemke, K.

2014-12-01

The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with results from molecular simulations of metal halides that are aimed at characterizing the nature (i.e. relativistic structures and energies) of metal clusters in water vapor.

Decontamination of chemical and biological warfare agents with a single multi-functional material.

PubMed

Amitai, Gabi; Murata, Hironobu; Andersen, Jill D; Koepsel, Richard R; Russell, Alan J

2010-05-01

We report the synthesis of new polymers based on a dimethylacrylamide-methacrylate (DMAA-MA) co-polymer backbone that support both chemical and biological agent decontamination. Polyurethanes containing the redox enzymes glucose oxidase and horseradish peroxidase can convert halide ions into active halogens and exert striking bactericidal activity against gram positive and gram negative bacteria. New materials combining those biopolymers with a family of N-alkyl 4-pyridinium aldoxime (4-PAM) halide-acrylate co-polymers offer both nucleophilic activity for the detoxification of organophosphorus nerve agents and internal sources of halide ions for generation of biocidal activity. Generation of free bromine and iodine was observed in the combined material resulting in bactericidal activity of the enzymatically formed free halogens that caused complete kill of E. coli (>6 log units reduction) within 1 h at 37 degrees C. Detoxification of diisopropylfluorophosphate (DFP) by the polyDMAA MA-4-PAM iodide component was dose-dependent reaching 85% within 30 min. A subset of 4-PAM-halide co-polymers was designed to serve as a controlled release reservoir for N-hydroxyethyl 4-PAM (HE 4-PAM) molecules that reactivate nerve agent-inhibited acetylcholinesterase (AChE). Release rates for HE 4-PAM were consistent with hydrolysis of the HE 4-PAM from the polymer backbone. The HE 4-PAM that was released from the polymer reactivated DFP-inhibited AChE at a similar rate to the oxime antidote 4-PAM. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Alkali reduction of graphene oxide in molten halide salts: production of corrugated graphene derivatives for high-performance supercapacitors.

PubMed

Abdelkader, Amr M; Vallés, Cristina; Cooper, Adam J; Kinloch, Ian A; Dryfe, Robert A W

2014-11-25

Herein we present a green and facile approach to the successful reduction of graphene oxide (GO) materials using molten halide flux at 370 °C. GO materials have been synthesized using a modified Hummers method and subsequently reduced for periods of up to 8 h. Reduced GO (rGO) flakes have been characterized using X-ray-diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR), all indicating a significantly reduced amount of oxygen-containing functionalities on the rGO materials. Furthermore, impressive electrical conductivities and electrochemical capacitances have been measured for the rGO flakes, which, along with the morphology determined from scanning electron microscopy, highlight the role of surface corrugation in these rGO materials.

Method for producing microcomposite powders using a soap solution

DOEpatents

Maginnis, Michael A.; Robinson, David A.

1996-01-01

A method for producing microcomposite powders for use in superconducting and non-superconducting applications. A particular method to produce microcomposite powders for use in superconducting applications includes the steps of: (a) preparing a solution including ammonium soap; (b) dissolving a preselected amount of a soluble metallic such as silver nitrate in the solution including ammonium soap to form a first solution; (c) adding a primary phase material such as a single phase YBC superconducting material in particle form to the first solution; (d) preparing a second solution formed from a mixture of a weak acid and an alkyl-mono-ether; (e) adding the second solution to the first solution to form a resultant mixture; (f) allowing the resultant mixture to set until the resultant mixture begins to cloud and thicken into a gel precipitating around individual particles of the primary phase material; (g) thereafter drying the resultant mixture to form a YBC superconducting material/silver nitrate precursor powder; and (h) calcining the YBC superconducting material/silver nitrate precursor powder to convert the silver nitrate to silver and thereby form a YBC/silver microcomposite powder wherein the silver is substantially uniformly dispersed in the matrix of the YBC material.

25 CFR 301.2 - Specifications of material.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 2 2010-04-01 2010-04-01 false Specifications of material. 301.2 Section 301.2 Indians INDIAN ARTS AND CRAFTS BOARD, DEPARTMENT OF THE INTERIOR NAVAJO, PUEBLO, AND HOPI SILVER AND TURQUOISE PRODUCTS; STANDARDS § 301.2 Specifications of material. Silver slugs of 1 ounce weight or other silver...

Method of Creating Micro-scale Silver Telluride Grains Covered with Bismuth Nanoparticles

NASA Technical Reports Server (NTRS)

Park, Yeonjoon (Inventor); Lee, Kunik (Inventor); Kim, Hyun-Jung (Inventor); Choi, Sang Hyouk (Inventor); King, Glen C. (Inventor)

2014-01-01

Provided is a method of enhancing thermoelectric performance by surrounding crystalline semiconductors with nanoparticles by contacting a bismuth telluride material with a silver salt under a substantially inert atmosphere and a temperature approximately near the silver salt decomposition temperature; and recovering a metallic bismuth decorated material comprising silver telluride crystal grains.

Resonance Raman and excitation energy dependent charge transfer mechanism in halide-substituted hybrid perovskite solar cells.

PubMed

Park, Byung-wook; Jain, Sagar M; Zhang, Xiaoliang; Hagfeldt, Anders; Boschloo, Gerrit; Edvinsson, Tomas

2015-02-24

Organo-metal halide perovskites (OMHPs) are materials with attractive properties for optoelectronics. They made a recent introduction in the photovoltaics world by methylammonium (MA) lead triiodide and show remarkably improved charge separation capabilities when chloride and bromide are added. Here we show how halide substitution in OMHPs with the nominal composition CH3NH3PbI2X, where X is I, Br, or Cl, influences the morphology, charge quantum yield, and local interaction with the organic MA cation. X-ray diffraction and photoluminescence data demonstrate that halide substitution affects the local structure in the OMHPs with separate MAPbI3 and MAPbCl3 phases. Raman spectroscopies as well as theoretical vibration calculations reveal that this at the same time delocalizes the charge to the MA cation, which can liberate the vibrational movement of the MA cation, leading to a more adaptive organic phase. The resonance Raman effect together with quantum chemical calculations is utilized to analyze the change in charge transfer mechanism upon electronic excitation and gives important clues for the mechanism of the much improved photovoltage and photocurrent also seen in the solar cell performance for the materials when chloride compounds are included in the preparation.

Lasing in robust cesium lead halide perovskite nanowires

DOE PAGES

Eaton, Samuel W.; Lai, Minliang; Gibson, Natalie A.; ...

2016-02-09

The rapidly growing field of nanoscale lasers can be advanced through the discovery of new, tunable light sources. The emission wavelength tunability demonstrated in perovskite materials is an attractive property for nanoscale lasers. Whereas organic-inorganic lead halide perovskite materials are known for their instability, cesium lead halides offer a robust alternative without sacrificing emission tunability or ease of synthesis. Here, we report the low-temperature, solution-phase growth of cesium lead halide nanowires exhibiting low-threshold lasing and high stability. The as-grown nanowires are single crystalline with well-formed facets, and act as high-quality laser cavities. The nanowires display excellent stability while stored andmore » handled under ambient conditions over the course of weeks. Upon optical excitation, Fabry-Pérot lasing occurs in CsPbBr 3 nanowires with an onset of 5 μJ cm -2 with the nanowire cavity displaying a maximum quality factor of 1,009 ± 5. Lasing under constant, pulsed excitation can be maintained for over 1 h, the equivalent of 10 9 excitation cycles, and lasing persists upon exposure to ambient atmosphere. Wavelength tunability in the green and blue regions of the spectrum in conjunction with excellent stability makes these nanowire lasers attractive for device fabrication.« less

Nanowire Lasers of Formamidinium Lead Halide Perovskites and Their Stabilized Alloys with Improved Stability

DOE PAGES

Fu, Yongping; Zhu, Haiming; Schrader, Alex W.; ...

2016-01-04

The excellent intrinsic optoelectronic properties of methylammonium lead halide perovskites (MAPbX 3, X = Br, I), such as high photoluminescence quantum efficiency, long carrier lifetime, and high gain coupled with the facile solution growth of nanowires make them promising new materials for ultralow-threshold nanowire lasers. However, their photo and thermal stabilities need to be improved for practical applications. Herein, we report a low-temperature solution growth of single crystal nanowires of formamidinium lead halide perovskites (FAPbX 3) that feature red-shifted emission and better thermal stability compared to MAPbX 3. We demonstrate optically pumped room-temperature near-infrared (~820 nm) and green lasing (~560more » nm) from FAPbI 3 (and MABr-stabilized FAPbI 3) and FAPbBr 3 nanowires with low lasing thresholds of several microjoules per square centimeter and high quality factors of about 1500–2300. More remarkably, the FAPbI 3 and MABr-stabilized FAPbI 3 nanowires display durable room-temperature lasing under ~10 8 shots of sustained illumination of 402 nm pulsed laser excitation (150 fs, 250 kHz), substantially exceeding the stability of MAPbI 3 (~10 7 laser shots). We further demonstrate tunable nanowire lasers in wider wavelength region from FA-based lead halide perovskite alloys (FA,MA)PbI 3 and (FA,MA)Pb(I,Br) 3 through cation and anion substitutions. The results suggest that formamidinium lead halide perovskite nanostructures could be more promising and stable materials for the development of light-emitting diodes and continuous-wave lasers.« less

Nanowire Lasers of Formamidinium Lead Halide Perovskites and Their Stabilized Alloys with Improved Stability.

PubMed

Fu, Yongping; Zhu, Haiming; Schrader, Alex W; Liang, Dong; Ding, Qi; Joshi, Prakriti; Hwang, Leekyoung; Zhu, X-Y; Jin, Song

2016-02-10

The excellent intrinsic optoelectronic properties of methylammonium lead halide perovskites (MAPbX3, X = Br, I), such as high photoluminescence quantum efficiency, long carrier lifetime, and high gain coupled with the facile solution growth of nanowires make them promising new materials for ultralow-threshold nanowire lasers. However, their photo and thermal stabilities need to be improved for practical applications. Herein, we report a low-temperature solution growth of single crystal nanowires of formamidinium lead halide perovskites (FAPbX3) that feature red-shifted emission and better thermal stability compared to MAPbX3. We demonstrate optically pumped room-temperature near-infrared (∼820 nm) and green lasing (∼560 nm) from FAPbI3 (and MABr-stabilized FAPbI3) and FAPbBr3 nanowires with low lasing thresholds of several microjoules per square centimeter and high quality factors of about 1500-2300. More remarkably, the FAPbI3 and MABr-stabilized FAPbI3 nanowires display durable room-temperature lasing under ∼10(8) shots of sustained illumination of 402 nm pulsed laser excitation (150 fs, 250 kHz), substantially exceeding the stability of MAPbI3 (∼10(7) laser shots). We further demonstrate tunable nanowire lasers in wider wavelength region from FA-based lead halide perovskite alloys (FA,MA)PbI3 and (FA,MA)Pb(I,Br)3 through cation and anion substitutions. The results suggest that formamidinium lead halide perovskite nanostructures could be more promising and stable materials for the development of light-emitting diodes and continuous-wave lasers.

Finding New Perovskite Halides via Machine learning

NASA Astrophysics Data System (ADS)

Pilania, Ghanshyam; Balachandran, Prasanna V.; Kim, Chiho; Lookman, Turab

2016-04-01

Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach towards rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning) via building a support vector machine (SVM) based classifier that uses elemental features (or descriptors) to predict the formability of a given ABX3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br or I anion) in the perovskite crystal structure. The classification model is built by learning from a dataset of 181 experimentally known ABX3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. The trained and validated models then predict, with a high degree of confidence, several novel ABX3 compositions with perovskite crystal structure.

Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liang, Dong; Peng, Yuelin; Fu, Yongping

Violet electroluminescence is rare in both inorganic and organic light-emitting diodes (LEDs). Low-cost and room- temperature solution-processed lead halide perovskites with high- efficiency and color-tunable photoluminescence are promising for LEDs. Here, we report room-temperature color-pure violet LEDs based on a two-dimensional lead halide perovskite material, namely, 2-phenylethylammonium (C 6H 5CH 2CH 2NH 3 +, PEA) lead bromide [(PEA) 2PbBr 4]. The natural quantum confinement of two-dimen- sional layered perovskite (PEA) 2PbBr 4 allows for photoluminescence of shorter wavelength (410 nm) than its three-dimensional counterpart. By converting as-deposited polycrystalline thin films to micrometer-sized (PEA) 2PbBr 4 nanoplates using solvent vapor annealing,more » we successfully integrated this layered perovskite material into LEDs and achieved efficient room-temperature violet electroluminescence at 410 nm with a narrow bandwidth. This conversion to nanoplates significantly enhanced the crystallinity and photophysical properties of the (PEA) 2PbBr 4 samples and the external quantum efficiency of the violet LED. Finally, the solvent vapor annealing method reported herein can be generally applied to other perovskite materials to increase their grain size and, ultimately, improve the performance of optoelectronic devices based on perovskite materials.« less

Color-Pure Violet-Light-Emitting Diodes Based on Layered Lead Halide Perovskite Nanoplates

DOE PAGES

Liang, Dong; Peng, Yuelin; Fu, Yongping; ...

2016-06-23

Violet electroluminescence is rare in both inorganic and organic light-emitting diodes (LEDs). Low-cost and room- temperature solution-processed lead halide perovskites with high- efficiency and color-tunable photoluminescence are promising for LEDs. Here, we report room-temperature color-pure violet LEDs based on a two-dimensional lead halide perovskite material, namely, 2-phenylethylammonium (C 6H 5CH 2CH 2NH 3 +, PEA) lead bromide [(PEA) 2PbBr 4]. The natural quantum confinement of two-dimen- sional layered perovskite (PEA) 2PbBr 4 allows for photoluminescence of shorter wavelength (410 nm) than its three-dimensional counterpart. By converting as-deposited polycrystalline thin films to micrometer-sized (PEA) 2PbBr 4 nanoplates using solvent vapor annealing,more » we successfully integrated this layered perovskite material into LEDs and achieved efficient room-temperature violet electroluminescence at 410 nm with a narrow bandwidth. This conversion to nanoplates significantly enhanced the crystallinity and photophysical properties of the (PEA) 2PbBr 4 samples and the external quantum efficiency of the violet LED. Finally, the solvent vapor annealing method reported herein can be generally applied to other perovskite materials to increase their grain size and, ultimately, improve the performance of optoelectronic devices based on perovskite materials.« less

Intriguing optoelectronic properties of metal halide perovskites

DOE PAGES

Manser, Joseph S.; Christians, Jeffrey A.; Kamat, Prashant V.

2016-06-21

Here, a new chapter in the long and distinguished history of perovskites is being written with the breakthrough success of metal halide perovskites (MHPs) as solution-processed photovoltaic (PV) absorbers. The current surge in MHP research has largely arisen out of their rapid progress in PV devices; however, these materials are potentially suitable for a diverse array of optoelectronic applications. Like oxide perovskites, MHPs have ABX 3 stoichiometry, where A and B are cations and X is a halide anion. Here, the underlying physical and photophysical properties of inorganic (A = inorganic) and hybrid organic-inorganic (A = organic) MHPs are reviewedmore » with an eye toward their potential application in emerging optoelectronic technologies. Significant attention is given to the prototypical compound methylammonium lead iodide (CH 3NH 3PbI 3) due to the preponderance of experimental and theoretical studies surrounding this material. We also discuss other salient MHP systems, including 2- dimensional compounds, where relevant. More specifically, this review is a critical account of the interrelation between MHP electronic structure, absorption, emission, carrier dynamics and transport, and other relevant photophysical processes that have propelled these materials to the forefront of modern optoelectronics research.« less

Antimicrobial activity and properties of irreversible hydrocolloid impression materials incorporated with silver nanoparticles.

PubMed

Ginjupalli, Kishore; Alla, Rama Krishna; Tellapragada, Chaitanya; Gupta, Lokendra; Upadhya Perampalli, Nagaraja

2016-06-01

Conventional spray and the immersion disinfection of irreversible hydrocolloid impression materials may lead to dimensional changes. The purpose of this in vitro study was to investigate the antimicrobial activity and properties of irreversible hydrocolloid impression materials incorporated with silver nanoparticles. The antimicrobial activity and properties of 2 commercially available irreversible hydrocolloid impression materials were evaluated after incorporating varying concentrations of silver nanoparticles. Antimicrobial activity was determined using the disk diffusion method. The gel strength, permanent deformation, flow, and gelation time were measured according to American Dental Association specification #18. Analysis of variance was used to identify the significant differences within and across the groups (α=.05). Adding silver nanoparticles to irreversible hydrocolloid impression materials resulted in superior antimicrobial activity without adversely affecting their properties. Adding silver nanoparticles to Zelgan significantly increased the gel strength compared with the control group, except at 5 wt%. However, the gel strength of Tropicalgin was unaffected except at 5 wt%. An increase in the permanent deformation was found with the incorporation of silver nanoparticles in both Zelgan and Tropicalgin. The flow of Zelgan increased with the incorporation of silver nanoparticles, whereas a decrease in the flow of Tropicalgin was observed at 1 wt% and 2 wt%. An increase in the gelation time of both Zelgan and Tropicalgin was observed with the incorporation of silver nanoparticles. Based on this in vitro study, silver nanoparticles can be incorporated into irreversible hydrocolloid impression materials as antimicrobial agents without adversely affecting their properties. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Development of processes for the production of solar grade silicon from halides and alkali metals

NASA Technical Reports Server (NTRS)

Dickson, C. R.; Gould, R. K.

1980-01-01

High temperature reactions of silicon halides with alkali metals for the production of solar grade silicon in volume at low cost were studied. Experiments were performed to evaluate product separation and collection processes, measure heat release parameters for scaling purposes, determine the effects of reactants and/or products on materials of reactor construction, and make preliminary engineering and economic analyses of a scaled-up process.

The lifecycle of silver in the United States in 2009

USGS Publications Warehouse

Goonan, Thomas G.

2014-01-01

Because silver is highly sought after for its properties, which make it eminently suitable for new technology applications, a clear understanding of the flow of materials in the economy, the historical context, and trends for the future can help project the future of silver in the economy of the United States. Silver has many properties that are desired in today’s economy. It has superior electrical and heat conductivity, chemical stability, high-temperature strength, malleability, and other characteristics that make it important in high-tech electronic and other industrial applications. Because it is relatively scarce as a natural resource and is easily coined, silver historically has been an important monetary metal. As knowledge of silver chemistry has increased, many industrial end uses have been developed. This study reviews the flows of silver into various end uses and examines the nature of the end use with respect to the silver properties desired and the ability of the end use to produce recyclable end-of-life materials. For the most part, silver can be profitably recycled, but the recycling activity is helped by tipping fees (fees imposed on scrap generators by scrap collectors for taking the material) for materials that might otherwise be regulated as hazardous wastes. New high-technology applications use silver in nanolevel amounts, leading to a potential for dissipative loss and reduced recycling capability.

Carboxylate and amino group coated silver nanoparticles as joining materials for copper-to-copper silver joints.

PubMed

Oestreicher, A; Röhrich, T; Lerch, M

2012-12-01

Organic silver complexes are introduced where silver is linked either with a carboxyl group or with an amino group. Upon heating, nanoparticles are generated if the respective ligands are long enough to act as stabilizing agents in the nanoparticulate regime. With decomposition and volatilization of the organic material, the sintering of silver occurs. The thermal characteristics of the carboxylates silver-n-octanoate, silver-n-decanoate, and AgOOC(CH2OCH2)2CH2OCH3 are compared with silver-n-alkylamines (n = 8, 9, and 12), and their thermal behavior is discussed based on thermogravimetry (TG) measurements. The consecutive stages of a metallization process are addressed based on the properties of AgOOC(CH2OCH2)2CH2OCH3, and the usable effects of the individual phases of this metal organic compound are analyzed by cross-sectional scanning electron microscope (SEM) images of silver joints. Selection criteria are addressed based on the thermal behavior. A mechanism for the joining process is proposed, considering formation and sintering of the nanoparticles. It was found that the bulk material can be used for low-temperature joining processes. Strong adherence to copper as a basic material can be achieved.

Old and modern Lippmann photography

NASA Astrophysics Data System (ADS)

Bjelkhagen, Hans I.; Jeong, Tung H.; Ro, Raymond J.

1998-02-01

At the end of the last century, Gabriel Lippmann was experimenting with color photography. His photographic color recording technique, Lippmann photography, produced very beautiful photographs and the fact that the colors are preserved in the early Lippmann photographs indicates something about their archival properties. Recent progress in color reflection holography has made it possible to take a new look at this one hundred year old photographic technique. Today, high-resolution panchromatic recording materials suitable for Lippmann photography are on the market. In particular, the Slavich panchromatic ultra-high- resolution silver-halide holographic materials have been investigated for modern Lippmann photography. Since the color photographs contain no dyes or pigments their archival stability may be high. In addition, a Lippmann photograph is difficult to copy which makes it a unique color photographic recording. Both of these features must attract a photographer interested in creating beautiful art photographs. It is also shown that Lippmann photographs can be made without the mercury reflector, instead by using the reflection from the gelatin-air interface. This eliminates the complications in dealing with mercury, while still maintaining the high resolution and picture quality at the expense of longer exposure times. Security application is a potential field for Lippmann photographs as well as optical filters. Another advantage is that no expensive equipment, such as lasers, is needed to explore this photographic recording technique; only a modified camera is required.

High-efficiency volume holograms recording on acrylamide and N,N'methylene-bis-acrylamide photopolymer with pulsed laser

NASA Astrophysics Data System (ADS)

Gallego, Sergi; Ortuno, Manuel; Garcia, Celia; Neipp, Cristian; Belendez, Augusto; Pascual, Inmaculada V.

2004-09-01

In order to achieve higher diffraction efficiencies of the volume gratings stored in acrylamide based photopolymer, we introduce in the photopolymer a crosslinker (N,N'methylene-bis-acrylamide). The presence of this component increase the rate polymerization and the modulation of refraction index. The recording was performed using a holographic copying process. The original was a grating of 1000 lines/mm processed using silver halide sensitized gelatine, with diffraction efficiency around 50 % for a reconstruction wavelength of 532 nm. The main beam was split in two secondary beams by the original grating, with an intensity ratio 1:1. The results obtained using the new composition of material are compared with the composition without crosslinker. In the other hand the no linearity of the material's response is also studied comparing the energetic sensitivity, diffraction efficiencies and index modulation of gratings recorded with pulsed and continuous laser. This study is realized fitting the angular scan of each grating using Kogelnik's theory. The gratings are recorded with wavelength of 532 nm when pulsed exposure is used and with wavelength of 514 nm when continues exposure is used. Using pulsed laser at 532 nm the photopolymer without crosslinker presents the diffraction efficiencies lightly smaller than 60%. In the other hand when the crosslinker has been introduced in photopolymer composition, the diffraction efficiencies achieves are higher than 85 %.

Infrared fiber optic evanescent wave spectroscopy: applications in biology and medicine

NASA Astrophysics Data System (ADS)

Afanasyeva, Natalia I.; Bruch, Reinhard F.; Katzir, Abraham

1999-04-01

A new powerful and highly sensitive technique for non-invasive biomedical diagnostics in vivo has been developed using Infrared Fiberoptic Evanescent Wave Fourier Transform Spectroscopy (FEW-FTIR). This compact and portable method allows to detect functional chemical groups and bonds via vibrational spectroscopy directly from surfaces including living tissue. Such differences and similarities in molecular structure of tissue and materials can be evaluated online. Operating in the attenuated total reflection (ATR) regime in the middle-infrared (MIR) range, the FEW-FTIR technique provides direct contact between the fiber probe and tissue for non-destructive, non-invasive, fast and remote (few meters) diagnostics and quality control of materials. This method utilizes highly flexible and extremely low loss unclad fibers, for example silver halide fibers. Applications of this method include investigations of normal skin, precancerous and cancerous conditions, monitoring of the process of aging, allergic reactions and radiation damage to the skin. This setup is suitable as well for the detection of the influence of environmental factors (sun, water, pollution, and weather) on skin surfaces. The FEW-FTIR technique is very promising also for fast histological examinations in vitro. In this review, we present recent investigations of skin, breast, lung, stomach, kidney tissues in vivo and ex vivo (during surgery) to define the areas of tumor localization. The main advantages of the FEW-FTIR technique for biomedical, clinical, and environmental applications are discussed.

Phonon Speed, Not Scattering, Differentiates Thermal Transport in Lead Halide Perovskites.

PubMed

Elbaz, Giselle A; Ong, Wee-Liat; Doud, Evan A; Kim, Philip; Paley, Daniel W; Roy, Xavier; Malen, Jonathan A

2017-09-13

Thermal management plays a critical role in the design of solid state materials for energy conversion. Lead halide perovskites have emerged as promising candidates for photovoltaic, thermoelectric, and optoelectronic applications, but their thermal properties are still poorly understood. Here, we report on the thermal conductivity, elastic modulus, and sound speed of a series of lead halide perovskites MAPbX 3 (X = Cl, Br, I), CsPbBr 3 , and FAPbBr 3 (MA = methylammonium, FA = formamidinium). Using frequency domain thermoreflectance, we find that the room temperature thermal conductivities of single crystal lead halide perovskites range from 0.34 to 0.73 W/m·K and scale with sound speed. These results indicate that regardless of composition, thermal transport arises from acoustic phonons having similar mean free path distributions. A modified Callaway model with Born von Karmen-based acoustic phonon dispersion predicts that at least ∼70% of thermal conductivity results from phonons having mean free paths shorter than 100 nm, regardless of whether resonant scattering is invoked. Hence, nanostructures or crystal grains with dimensions smaller than 100 nm will appreciably reduce thermal transport. These results are important design considerations to optimize future lead halide perovskite-based photovoltaic, optoelectronic, and thermoelectric devices.

Octahedral tilting instabilities in inorganic halide perovskites

NASA Astrophysics Data System (ADS)

Bechtel, Jonathon S.; Van der Ven, Anton

2018-02-01

Dynamic instabilities, stabilized by anharmonic interactions in cubic and tetragonal halide perovskites at high temperature, play a role in the electronic structure and optoelectronic properties of halide perovskites. In particular, inorganic and hybrid perovskite materials undergo structural phase transitions associated with octahedral tilts of the metal-halide octahedra. We investigate the structural instabilities present in inorganic Cs M X3 perovskites with Pb or Sn on the metal site and Br or I on the X site. Defining primary order parameters in terms of symmetry-adapted collective displacement modes and secondary order parameters in terms of symmetrized Hencky strain components, we unravel the coupling between octahedral tilt modes and macroscopic strains as well as the role of A -site displacements in perovskite phase stability. Symmetry-allowed secondary strain order parameters are enumerated for the 14 unique perovskite tilt systems. Using first-principles calculations to explore the Born-Oppenheimer energy surface in terms of symmetrized order parameters, we find coupling between octahedral tilting and A -site displacements is necessary to stabilize P n m a ground states. Additionally, we show that the relative stability of an inorganic halide perovskite tilt system correlates with the volume decrease from the high-symmetry cubic phase to the low-symmetry distorted phase.

Broad Wavelength Tunable Robust Lasing from Single-Crystal Nanowires of Cesium Lead Halide Perovskites (CsPbX3, X = Cl, Br, I).

PubMed

Fu, Yongping; Zhu, Haiming; Stoumpos, Constantinos C; Ding, Qi; Wang, Jue; Kanatzidis, Mercouri G; Zhu, Xiaoyang; Jin, Song

2016-08-23

Lead halide perovskite nanowires (NWs) are emerging as a class of inexpensive semiconductors with broad bandgap tunability for optoelectronics, such as tunable NW lasers. Despite exciting progress, the current organic-inorganic hybrid perovskite NW lasers suffer from limited tunable wavelength range and poor material stability. Herein, we report facile solution growth of single-crystal NWs of inorganic perovskite CsPbX3 (X = Br, Cl) and their alloys [CsPb(Br,Cl)3] and a low-temperature vapor-phase halide exchange method to convert CsPbBr3 NWs into perovskite phase CsPb(Br,I)3 alloys and metastable CsPbI3 with well-preserved perovskite crystal lattice and NW morphology. These single crystalline NWs with smooth end facets and subwavelength dimensions are ideal Fabry-Perot cavities for NW lasers. Optically pumped tunable lasing across the entire visible spectrum (420-710 nm) is demonstrated at room temperature from these NWs with low lasing thresholds and high-quality factors. Such highly efficient lasing similar to what can be achieved with organic-inorganic hybrid perovskites indicates that organic cation is not essential for light emission application from these lead halide perovskite materials. Furthermore, the CsPbBr3 NW lasers show stable lasing emission with no measurable degradation after at least 8 h or 7.2 × 10(9) laser shots under continuous illumination, which are substantially more robust than their organic-inorganic counterparts. The Cs-based perovskites offer a stable material platform for tunable NW lasers and other nanoscale optoelectronic devices.

Large dielectric constant, high acceptor density, and deep electron traps in perovskite solar cell material CsGeI 3

DOE PAGES

Ming, Wenmei; Shi, Hongliang; Du, Mao-Hua

2016-01-01

Here we report that many metal halides that contain cations with the ns 2 electronic configuration have recently been discovered as high-performance optoelectronic materials. In particular, solar cells based on lead halide perovskites have shown great promise as evidenced by the rapid increase of the power conversion efficiency. In this paper, we show density functional theory calculations of electronic structure and dielectric and defect properties of CsGeI 3 (a lead-free halide perovskite material). The potential of CsGeI 3 as a solar cell material is assessed based on its intrinsic properties. We find anomalously large Born effective charges and a largemore » static dielectric constant dominated by lattice polarization, which should reduce carrier scattering, trapping, and recombination by screening charged defects and impurities. Defect calculations show that CsGeI 3 is a p-type semiconductor and its hole density can be modified by varying the chemical potentials of the constituent elements. Despite the reduction of long-range Coulomb attraction by strong screening, the iodine vacancy in CsGeI3 is found to be a deep electron trap due to the short-range potential, i.e., strong Ge–Ge covalent bonding, which should limit electron transport efficiency in p-type CsGeI 3. This is in contrast to the shallow iodine vacancies found in several Pb and Sn halide perovskites (e.g., CH 3NH 3PbI 3, CH 3NH 3SnI 3, and CsSnI 3). The low-hole-density CsGeI 3 may be a useful solar absorber material but the presence of the low-energy deep iodine vacancy may significantly reduce the open circuit voltage of the solar cell. Still, on the other hand, CsGeI 3 may be used as an efficient hole transport material in solar cells due to its small hole effective mass, the absence of low-energy deep hole traps, and the favorable band offset with solar absorber materials such as dye molecules and CH 3NH 3PbI 3.« less

Silver-functionalized silica aerogels and their application in the removal of iodine from aqueous environments

DOE PAGES

Asmussen, R. Matthew; Matyas, Josef; Qafoku, Nikolla P.; ...

2018-05-01

Here, one of the key challenges for radioactive waste management is the efficient capture and immobilization of radioiodine, because of its radiotoxicity, high mobility in the environment, and long half-life (t 1/2 = 1.57 × 10 7 years). Silver-functionalized silica aerogel (AgAero) represents a strong candidate for safe sequestration of radioiodine from various nuclear waste streams and subsurface environments. Batch sorption experiments up to 10 days long were carried out in oxic and anoxic conditions in both deionized water (DIW) and various Hanford Site Waste Treatment Plant (WTP) off-gas condensate simulants containing from 5 to 10 ppm of iodide (Imore » –) or iodate (IO 3 –). Also tested was the selectivity of AgAero towards I – in the presence of other halide anions. AgAero exhibited fast and complete removal of I – from DIW, slower but complete removal of I – from WTP off-gas simulants, preferred removal of I – over Br – and Cl –, and it demonstrated ability to remove IO 3 – through reduction to I –.« less

Silver-functionalized silica aerogels and their application in the removal of iodine from aqueous environments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Asmussen, R. Matthew; Matyas, Josef; Qafoku, Nikolla P.

Here, one of the key challenges for radioactive waste management is the efficient capture and immobilization of radioiodine, because of its radiotoxicity, high mobility in the environment, and long half-life (t 1/2 = 1.57 × 10 7 years). Silver-functionalized silica aerogel (AgAero) represents a strong candidate for safe sequestration of radioiodine from various nuclear waste streams and subsurface environments. Batch sorption experiments up to 10 days long were carried out in oxic and anoxic conditions in both deionized water (DIW) and various Hanford Site Waste Treatment Plant (WTP) off-gas condensate simulants containing from 5 to 10 ppm of iodide (Imore » –) or iodate (IO 3 –). Also tested was the selectivity of AgAero towards I – in the presence of other halide anions. AgAero exhibited fast and complete removal of I – from DIW, slower but complete removal of I – from WTP off-gas simulants, preferred removal of I – over Br – and Cl –, and it demonstrated ability to remove IO 3 – through reduction to I –.« less

Surface enhanced Raman scattering by a new derivative of acridine in solutions of colloidal silver

NASA Astrophysics Data System (ADS)

Solovyeva, E. V.; Khaziyeva, D. A.; Myund, L. A.; Denisova, A. S.

2017-03-01

A new derivative of acridine, 4,5-bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA), which is a selective fluorophore relative to cadmium cations, is studied by the method of surface-enhanced Raman scattering (SERS). The SERS spectra of BHIA adsorbed on colloidal silver particles exhibit a high intensity and temporal stability of the signal. An assignment of the bands present in the studied spectral range is given. The dependence of the SERS spectra of BHIA on the solution's pH reveals that the ligand can exist on the surface in protonated and deprotonated forms. The stability of the deprotonated form on the surface suggests that the ligand interacts with the surface by means of a conjugated π-system of aromatic rings. The addition of the salt of halide ions to the solution has a significant influence on the SERS spectrum. This effect is due to the displacement of the adsorbate molecules from the first monolayer, which is accompanied by the transition of BHIA from the chemi- to the physisorbed form.

Silver-functionalized silica aerogels and their application in the removal of iodine from aqueous environments.

PubMed

Asmussen, R Matthew; Matyáš, Josef; Qafoku, Nikolla P; Kruger, Albert A

2018-05-01

One of the key challenges for radioactive waste management is the efficient capture and immobilization of radioiodine, because of its radiotoxicity, high mobility in the environment, and long half-life (t 1/2  = 1.57 × 10 7 years). Silver-functionalized silica aerogel (AgAero) represents a strong candidate for safe sequestration of radioiodine from various nuclear waste streams and subsurface environments. Batch sorption experiments up to 10 days long were carried out in oxic and anoxic conditions in both deionized water (DIW) and various Hanford Site Waste Treatment Plant (WTP) off-gas condensate simulants containing from 5 to 10 ppm of iodide (I - ) or iodate (IO 3 - ). Also tested was the selectivity of AgAero towards I - in the presence of other halide anions. AgAero exhibited fast and complete removal of I - from DIW, slower but complete removal of I - from WTP off-gas simulants, preferred removal of I - over Br - and Cl - , and it demonstrated ability to remove IO 3 - through reduction to I - . Copyright © 2018 Elsevier B.V. All rights reserved.

Yb-doped large-mode-area laser fiber fabricated by halide-gas-phase-doping technique

NASA Astrophysics Data System (ADS)

Peng, Kun; Wang, Yuying; Ni, Li; Wang, Zhen; Gao, Cong; Zhan, Huan; Wang, Jianjun; Jing, Feng; Lin, Aoxiang

2015-06-01

In this manuscript, we designed a rare-earth-halide gas-phase-doping setup to fabricate a large-mode-area fiber for high power laser applications. YbCl3 and AlCl3 halides are evaporated, carried respectively and finally mixed with usual host gas material SiCl4 at the hot zone of MCVD system. Owing to the all-gas-phasing reaction process and environment, the home-made Yb-doped fiber preform has a homogeneous large core and modulated refractive index profile to keep high beam quality. The drawn fiber core has a small numerical aperture of 0.07 and high Yb concentration of 9500 ppm. By using a master oscillator power amplifier system, nearly kW-level (951 W) laser output power was obtained with a slope efficiency of 83.3% at 1063.8 nm, indicating the competition and potential of the halide-gas-phase-doping technique for high power laser fiber fabrication.

Extraction of trace metals from fly ash

DOEpatents

Blander, M.; Wai, C.M.; Nagy, Z.

1983-08-15

A process is described for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous. The fly ash has a silicate base and contains surface deposits of the trace metals as oxides, chlorides or the like. The process is carried out by contacting the fly ash with AlCl/sub 3/ in an alkali halide melt to react the trace metals with the AlCl/sub 3/ to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Extraction of trace metals from fly ash

DOEpatents

Blander, Milton; Wai, Chien M.; Nagy, Zoltan

1984-01-01

A process for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous, the fly ash having a silicate base and containing surface deposits of the trace metals as oxides, chlorides or the like, with the process being carried out by contacting the fly ash with AlCl.sub.3 in an alkali halide melt to react the trace metals with the AlCl.sub.3 to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Novel polymeric LIT and divalent cation fast ion conducting materials

NASA Astrophysics Data System (ADS)

Angell, C. A.

Solid state energy devices require a component which conducts electricity by ionic migration. The conductivity of this element of the system must be very high. Four types of materials show the promise to provide the necessary conductivity characteristics, while offering other desirable features such as the ability to distort in shape under mechanical stresses: (1) crystalline; (2) plastic crystal; (3) inorganic glassy; and (4) polymer salt solutions. This document reports on the following materials: lead halide-containing fast ion conducting glasses (LiF-PbF2-Al(PO3)3), mixed ionic electronic conduction (Na2O-V2O5-TeO2), alpha relaxation in ionic glasses, glass transition in P2O2, and conductivity transition between all-halide and all-oxide glasses.

Phase Segregation in Potassium-Doped Lead Halide Perovskites from 39K Solid-State NMR at 21.1 T.

PubMed

Kubicki, Dominik J; Prochowicz, Daniel; Hofstetter, Albert; Zakeeruddin, Shaik M; Grätzel, Michael; Emsley, Lyndon

2018-06-13

Organic-inorganic lead halide perovskites are a promising family of light absorbers for a new generation of solar cells, with reported efficiencies currently exceeding 22%. A common problem of solar cells fabricated using these materials is that their efficiency depends on their cycling history, an effect known as current-voltage ( J- V) hysteresis. Potassium doping has recently emerged as a universal way to overcome this adverse phenomenon. While the atomistic origins of J- V hysteresis are still not fully understood, it is essential to rationalize the atomic-level effect of protocols that lead to its suppression. Here, using 39 K MAS NMR at 21.1 T we provide for the first time atomic-level characterization of the potassium-containing phases that are formed upon KI doping of multication and multianion lead halide perovskites. We find no evidence of potassium incorporation into 3D perovskite lattices of the recently reported materials. Instead, we observe formation of a mixture of potassium-rich phases and unreacted KI. In the case of Br-containing lead halide perovskites doped with KI, a mixture of KI and KBr ensues, leading to a change in the Br/I ratio in the perovskite phase with respect to the undoped perovskite. Simultaneous Cs and K doping leads to the formation of nonperovskite Cs/K lead iodide phases.

High Color Rendering Index White-Light Emission from UV-Driven LEDs Based on Single Luminescent Materials: Two-Dimensional Perovskites (C6H5C2H4NH3)2PbBr xCl4- x.

PubMed

Yang, Shuming; Lin, Zhenghuan; Wang, Jingwei; Chen, Yunxiang; Liu, Zhengde; Yang, E; Zhang, Jian; Ling, Qidan

2018-05-09

Two-dimensional (2D) white-light-emitting hybrid perovskites (WHPs) are promising active materials for single-component white-light-emitting diodes (WLEDs) driven by UV. However, the reported WHPs exhibit low quantum yields (≤9%) and low color rendering index (CRI) values less than 85, which does not satisfy the demand of solid-state lighting applications. In this work, we report a series of mixed-halide 2D layered WHPs (C 6 H 5 C 2 H 4 NH 3 ) 2 PbBr x Cl 4- x (0 < x < 4) obtained from the phenethylammonium cation. Unlike the reported WHPs including (C 6 H 5 C 2 H 4 NH 3 ) 2 PbCl 4 , the mixed-halide perovskites display morphology-dependent white emission for the different extents of self-absorption. Additionally, the amount of Br has a huge influence on the photophysical properties of mixed-halide WHPs. With the increasing content of Br, the quantum yields of WHPs increase gradually from 0.2 to 16.9%, accompanied by tunable color temperatures ranging from 4000 K ("warm" white light) to 7000 K ("cold" white light). When applied to the WLEDs, the mixed-halide perovskite powders exhibit tunable white electroluminescent emission with very high CRI of 87-91.

Ceramicrete stabilization of U-and Pu-bearing materials

DOEpatents

Wagh, Arun S.; Maloney, M. David; Thompson, Gary H.

2007-11-13

A method of stabilizing nuclear material is disclosed. Oxides or halides of actinides and/or transuranics (TRUs) and/or hydrocarbons and/or acids contaminated with actinides and/or TRUs are treated by adjusting the pH of the nuclear material to not less than about 5 and adding sufficient MgO to convert fluorides present to MgF.sub.2; alumina is added in an amount sufficient to absorb substantially all hydrocarbon liquid present, after which a binder including MgO and KH.sub.2PO.sub.4 is added to the treated nuclear material to form a slurry. Additional MgO may be added. A crystalline radioactive material is also disclosed having a binder of the reaction product of calcined MgO and KH.sub.2PO.sub.4 and a radioactive material of the oxides and/or halides of actinides and/or transuranics (TRUs). Acids contaminated with actinides and/or TRUs, and/or actinides and/or TRUs with or without oils and/or greases may be encapsulated and stabilized by the binder.

Three-body wear of a hand-consolidated silver alternative to amalgam.

PubMed

Xu, H H; Eichmiller, F C; Giuseppetti, A A; Ives, L K; Parry, E E; Schumacher, G E

1999-09-01

Recent studies have investigated a mercury-free silver alternative to amalgam, but the silver powders required a relatively high compaction pressure to consolidate. The aim of the present study was to consolidate a precipitated silver powder into a cohesive solid using an air-driven pneumatic condenser fitted with an amalgam plugger at a clinically realistic load, and to study the mechanisms and rates of three-body wear of the consolidated silver in comparison with that of an amalgam. The silver powder was annealed, rinsed with a dilute acid, and consolidated either in a prepared tooth cavity or in a specimen mold at a load of 15 N. A four-station wear machine was used where each specimen was immersed in a slurry containing polymethyl methacrylate beads, then a steel pin was loaded and rotated against the specimen at a maximum load of 76 N. The flexural strength in MPa (mean +/- SD; n = 10) was 86 +/- 20 for amalgam, 181 +/- 45 for silver with a polished surface, and 202 +/- 21 for silver with a burnished surface. After 4 x 10(5) wear cycles, the wear scar depth in microm was 134 +/- 54 for amalgam, 143 +/- 8 for polished silver, and 131 +/- 9 for burnished silver, which were not significantly different (Tukey's multiple comparison test; family confidence coefficient = 0.95). SEM examination revealed cracks and fracture pits in the worn surface of amalgam, in contrast to a smooth surface in silver. Wear and material removal in amalgam occurred by microfracture and dislodgement of cracked segments, while wear in the silver occurred by ductile deformation and flow of materials. To conclude, the consolidated silver possesses a three-body wear resistance similar to that of amalgam, and a higher resistance to wear-induced damage and cracking than amalgam. The mechanism of wear in amalgam is microfracture and material dislodgement, while that in consolidated silver is ductile deformation and flow of material.

Design Principles for the Atomic and Electronic Structure of Halide Perovskite Photovoltaic Materials: Insights from Computation.

PubMed

Berger, Robert F

2018-02-09

In the current decade, perovskite solar cell research has emerged as a remarkably active, promising, and rapidly developing field. Alongside breakthroughs in synthesis and device engineering, halide perovskite photovoltaic materials have been the subject of predictive and explanatory computational work. In this Minireview, we focus on a subset of this computation: density functional theory (DFT)-based work highlighting the ways in which the electronic structure and band gap of this class of materials can be tuned via changes in atomic structure. We distill this body of computational literature into a set of underlying design principles for the band gap engineering of these materials, and rationalize these principles from the viewpoint of band-edge orbital character. We hope that this perspective provides guidance and insight toward the rational design and continued improvement of perovskite photovoltaics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Giant photostriction in organic–inorganic lead halide perovskites

PubMed Central

Zhou, Yang; You, Lu; Wang, Shiwei; Ku, Zhiliang; Fan, Hongjin; Schmidt, Daniel; Rusydi, Andrivo; Chang, Lei; Wang, Le; Ren, Peng; Chen, Liufang; Yuan, Guoliang; Chen, Lang; Wang, Junling

2016-01-01

Among the many materials investigated for next-generation photovoltaic cells, organic–inorganic lead halide perovskites have demonstrated great potential thanks to their high power conversion efficiency and solution processability. Within a short period of about 5 years, the efficiency of solar cells based on these materials has increased dramatically from 3.8 to over 20%. Despite the tremendous progress in device performance, much less is known about the underlying photophysics involving charge–orbital–lattice interactions and the role of the organic molecules in this hybrid material remains poorly understood. Here, we report a giant photostrictive response, that is, light-induced lattice change, of >1,200 p.p.m. in methylammonium lead iodide, which could be the key to understand its superior optical properties. The strong photon-lattice coupling also opens up the possibility of employing these materials in wireless opto-mechanical devices. PMID:27044485

Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

DOEpatents

Sarin, V.K.

1991-07-30

A process is disclosed for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900--1500 C and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

Process for the deposition of high temperature stress and oxidation resistant coatings on silicon-based substrates

DOEpatents

Sarin, Vinod K.

1991-01-01

A process for depositing a high temperature stress and oxidation resistant coating on a silicon nitride- or silicon carbide-based substrate body. A gas mixture is passed over the substrate at about 900.degree.-1500.degree. C. and about 1 torr to about ambient pressure. The gas mixture includes one or more halide vapors with other suitable reactant gases. The partial pressure ratios, flow rates, and process times are sufficient to deposit a continuous, fully dense, adherent coating. The halide and other reactant gases are gradually varied during deposition so that the coating is a graded coating of at least two layers. Each layer is a graded layer changing in composition from the material over which it is deposited to the material of the layer and further to the material, if any, deposited thereon, so that no clearly defined compositional interfaces exist. The gases and their partial pressures are varied according to a predetermined time schedule and the halide and other reactant gases are selected so that the layers include (a) an adherent, continuous intermediate layer about 0.5-20 microns thick of an aluminum nitride or an aluminum oxynitride material, over and chemically bonded to the substrate body, and (b) an adherent, continuous first outer layer about 0.5-900 microns thick including an oxide of aluminum or zirconium over and chemically bonded to the intermediate layer.

Finding new perovskite halides via machine learning

DOE PAGES

Pilania, Ghanshyam; Balachandran, Prasanna V.; Kim, Chiho; ...

2016-04-26

Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach toward rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning, henceforth referred to as ML) via building a support vectormore » machine (SVM) based classifier that uses elemental features (or descriptors) to predict the formability of a given ABX 3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br, or I anion) in the perovskite crystal structure. The classification model is built by learning from a dataset of 185 experimentally known ABX 3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor, and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. As a result, the trained and validated models then predict, with a high degree of confidence, several novel ABX 3 compositions with perovskite crystal structure.« less

Finding new perovskite halides via machine learning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pilania, Ghanshyam; Balachandran, Prasanna V.; Kim, Chiho

Advanced materials with improved properties have the potential to fuel future technological advancements. However, identification and discovery of these optimal materials for a specific application is a non-trivial task, because of the vastness of the chemical search space with enormous compositional and configurational degrees of freedom. Materials informatics provides an efficient approach toward rational design of new materials, via learning from known data to make decisions on new and previously unexplored compounds in an accelerated manner. Here, we demonstrate the power and utility of such statistical learning (or machine learning, henceforth referred to as ML) via building a support vectormore » machine (SVM) based classifier that uses elemental features (or descriptors) to predict the formability of a given ABX 3 halide composition (where A and B represent monovalent and divalent cations, respectively, and X is F, Cl, Br, or I anion) in the perovskite crystal structure. The classification model is built by learning from a dataset of 185 experimentally known ABX 3 compounds. After exploring a wide range of features, we identify ionic radii, tolerance factor, and octahedral factor to be the most important factors for the classification, suggesting that steric and geometric packing effects govern the stability of these halides. As a result, the trained and validated models then predict, with a high degree of confidence, several novel ABX 3 compositions with perovskite crystal structure.« less

2D halide perovskite-based van der Waals heterostructures: contact evaluation and performance modulation

NASA Astrophysics Data System (ADS)

Guo, Yaguang; Saidi, Wissam A.; Wang, Qian

2017-09-01

Halide perovskites and van der Waals (vdW) heterostructures are both of current interest owing to their novel properties and potential applications in nano-devices. Here, we show the great potential of 2D halide perovskite sheets (C4H9NH3)2PbX4 (X  =  Cl, Br and I) that were synthesized recently (Dou et al 2015 Science 349 1518-21) as the channel materials contacting with graphene and other 2D metallic sheets to form van der Waals heterostructures for field effect transistor (FET). Based on state-of-the-art theoretical simulations, we show that the intrinsic properties of the 2D halide perovskites are preserved in the heterojunction, which is different from the conventional contact with metal surfaces. The 2D halide perovskites form a p-type Schottky barrier (Φh) contact with graphene, where tunneling barrier exists, and a negative band bending occurs at the lateral interface. We demonstrate that the Schottky barrier can be turned from p-type to n-type by doping graphene with nitrogen atoms, and a low-Φh or an Ohmic contact can be realized by doping graphene with boron atoms or replacing graphene with other high-work-function 2D metallic sheets such as ZT-MoS2, ZT-MoSe2 and H-NbS2. This study not only predicts a 2D halide perovskite-based FETs, but also enhances the understanding of tuning Schottky barrier height in device applications.

Laboratory strength of glass ionomer and zinc phosphate cements.

PubMed

Piwowarczyk, A; Ottl, P; Lauer, H C

2001-09-01

The present in vitro study examined 3 mechanical properties, namely compressive, flexural, and diametral tensile strength, of various commercially available cements and core materials as a function of time after mixing. The examined materials were 2 cermet cements (Ketac Silver [ESPE, Seefeld, Germany] and Chelon Silver [ESPE]), 1 metal-reinforced glass ionomer cement (Miracle Mix [GC Dental Industrial Corp, Tokyo, Japan]), 2 conventional glass ionomer cements (Ketac Bond [ESPE] and Ketac Cem [ESPE]), 1 standard cure zinc phosphate cement (Harvard Cement [Richter and Hoffmann, Berlin, Germany]), and 1 zinc phosphate cement with the addition of 30% silver amalgam alloy powder (Harvard Cement 70% with Dispersalloy 30% [Richter and Hoffmann/Johnson and Johnson, East Windsor, NJ]). Properties were measured using a universal testing machine at 15 minutes, 1 hour, and 24 hours after first mixing. Compressive strengths varied widely between the 3 times of measurement from 5.8 +/- 6.6 MPa for Ketac Cem to 144.3 +/- 10.2 MPa for Ketac Silver. Twenty-four hours after mixing, the Bonferroni test showed significant (p

Acoustic-optical phonon up-conversion and hot-phonon bottleneck in lead-halide perovskites

PubMed Central

Yang, Jianfeng; Wen, Xiaoming; Xia, Hongze; Sheng, Rui; Ma, Qingshan; Kim, Jincheol; Tapping, Patrick; Harada, Takaaki; Kee, Tak W.; Huang, Fuzhi; Cheng, Yi-Bing; Green, Martin; Ho-Baillie, Anita; Huang, Shujuan; Shrestha, Santosh; Patterson, Robert; Conibeer, Gavin

2017-01-01

The hot-phonon bottleneck effect in lead-halide perovskites (APbX3) prolongs the cooling period of hot charge carriers, an effect that could be used in the next-generation photovoltaics devices. Using ultrafast optical characterization and first-principle calculations, four kinds of lead-halide perovskites (A=FA+/MA+/Cs+, X=I−/Br−) are compared in this study to reveal the carrier-phonon dynamics within. Here we show a stronger phonon bottleneck effect in hybrid perovskites than in their inorganic counterparts. Compared with the caesium-based system, a 10 times slower carrier-phonon relaxation rate is observed in FAPbI3. The up-conversion of low-energy phonons is proposed to be responsible for the bottleneck effect. The presence of organic cations introduces overlapping phonon branches and facilitates the up-transition of low-energy modes. The blocking of phonon propagation associated with an ultralow thermal conductivity of the material also increases the overall up-conversion efficiency. This result also suggests a new and general method for achieving long-lived hot carriers in materials. PMID:28106061

First-principles study of electronic and optical properties of lead-free double perovskites Cs2NaBX6 (B = Sb, Bi; X = Cl, Br, I)

NASA Astrophysics Data System (ADS)

Zhao, Shuai; Yamamoto, Kumiko; Iikubo, Satoshi; Hayase, Shuzi; Ma, Tingli

2018-06-01

Organolead halide perovskite is regarded as the most promising light-harvesting material for next-generation solar cells; however, the intrinsic instability and toxicity of lead are still of great concern. Bismuth is ecofriendly and has electronic properties similar to those of lead, which has gradually attracted interest for optoelectronic applications. However, the valence state of bismuth is different from that of lead, eliminating the possibility of replacing lead by bismuth in organolead halide perovskites. To address this matter, one feasible strategy is to construct B-site double perovskites by the combination of Bi3+ and B+ in 1:1 ratio. In this work, lead-free halide double perovskites of the form Cs2NaBX6 (B = Sb, Bi; X = Cl, Br, I) were investigated by first-principles calculations. The electronic properties, optical absorption coefficients, and thermodynamic stability of these compounds were investigated to ascertain their potential application in solar energy conversion. The results provide theoretical support for the exploration of lead-free perovskite materials in potential optoelectronic applications.

Control of Silver Diffusion in Low-Temperature Co-Fired Diopside Glass-Ceramic Microwave Dielectrics

PubMed Central

Chou, Chen-Chia; Chang, Chun-Yao; Chen, Guang-Yu; Feng, Kuei-Chih; Tsao, Chung-Ya

2017-01-01

Electrode material for low-temperature co-fired diopside glass-ceramic used for microwave dielectrics was investigated in the present work. Diffusion of silver from the electrode to diopside glass-ceramics degrades the performance of the microwave dielectrics. Two approaches were adopted to resolve the problem of silver diffusion. Firstly, silicon-oxide (SiO2) powder was employed and secondly crystalline phases were chosen to modify the sintering behavior and inhibit silver ions diffusion. Nanoscale amorphous SiO2 powder turns to the quartz phase uniformly in dielectric material during the sintering process, and prevents the silver from diffusion. The chosen crystalline phase mixing into the glass-ceramics enhances crystallinity of the material and inhibits silver diffusion as well. The result provides a method to decrease the diffusivity of silver ions by adding the appropriate amount of SiO2 and appropriate crystalline ceramics in diopside glass-ceramic dielectric materials. Finally, we used IEEE 802.11a 5.8 GHz as target specification to manufacture LTCC antenna and the results show that a good broadband antenna was made using CaMgSi2O6 with 4 wt % silicon oxide. PMID:29286330

Alkali Metal/Salt Thermal-Energy-Storage Systems

NASA Technical Reports Server (NTRS)

Phillips, Wayne W.; Stearns, John W.

1987-01-01

Proposed thermal-energy-storage system based on mixture of alkali metal and one of its halide salts; metal and salt form slurry of two immiscible melts. Use of slurry expected to prevent incrustations of solidified salts on heat-transfer surfaces that occur where salts alone used. Since incrustations impede heat transfer, system performance improved. In system, charging heat-exchanger surface immersed in lower liquid, rich in halide-salt, phase-charge material. Discharging heat exchanger surface immersed in upper liquid, rich in alkali metal.

Laser Direct Write Synthesis of Lead Halide Perovskites

DOE PAGES

Chou, Stanley S.; Swartzentruber, Brian S.; Janish, Matthew T.; ...

2016-09-05

Lead halide perovskites are increasingly considered for applications beyond photovoltaics, for example, light emission and detection, where an ability to pattern and prototype microscale geometries can facilitate the incorporation of this class of materials into devices. In this study, we demonstrate laser direct write of lead halide perovskites, a remarkably simple procedure that takes advantage of the inverse dependence between perovskite solubility and temperature by using a laser to induce localized heating of an absorbing substrate. We also demonstrate arbitrary pattern formation of crystalline CH 3NH 3PbBr 3 on a range of substrates and fabricate and characterize a microscale photodetectormore » using this approach. This direct write methodology provides a path forward for the prototyping and production of perovskite-based devices.« less

Laser Direct Write Synthesis of Lead Halide Perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chou, Stanley S.; Swartzentruber, Brian S.; Janish, Matthew T.

Lead halide perovskites are increasingly considered for applications beyond photovoltaics, for example, light emission and detection, where an ability to pattern and prototype microscale geometries can facilitate the incorporation of this class of materials into devices. In this study, we demonstrate laser direct write of lead halide perovskites, a remarkably simple procedure that takes advantage of the inverse dependence between perovskite solubility and temperature by using a laser to induce localized heating of an absorbing substrate. We also demonstrate arbitrary pattern formation of crystalline CH 3NH 3PbBr 3 on a range of substrates and fabricate and characterize a microscale photodetectormore » using this approach. This direct write methodology provides a path forward for the prototyping and production of perovskite-based devices.« less

Solution-Phase Synthesis of Cesium Lead Halide Perovskite Nanowires.

PubMed

Zhang, Dandan; Eaton, Samuel W; Yu, Yi; Dou, Letian; Yang, Peidong

2015-07-29

Halide perovskites have attracted much attention over the past 5 years as a promising class of materials for optoelectronic applications. However, compared to hybrid organic-inorganic perovskites, the study of their pure inorganic counterparts, like cesium lead halides (CsPbX3), lags far behind. Here, a catalyst-free, solution-phase synthesis of CsPbX3 nanowires (NWs) is reported. These NWs are single-crystalline, with uniform growth direction, and crystallize in the orthorhombic phase. Both CsPbBr3 and CsPbI3 are photoluminescence active, with composition-dependent temperature and self-trapping behavior. These NWs with a well-defined morphology could serve as an ideal platform for the investigation of fundamental properties and the development of future applications in nanoscale optoelectronic devices based on all-inorganic perovskites.

Influence of halide composition on the structural, electronic, and optical properties of mixed CH3NH3Pb (I1-xBrx) 3 perovskites calculated using the virtual crystal approximation method

NASA Astrophysics Data System (ADS)

Jong, Un-Gi; Yu, Chol-Jun; Ri, Jin-Song; Kim, Nam-Hyok; Ri, Guk-Chol

2016-09-01

Extensive studies have demonstrated the promising capability of the organic-inorganic hybrid halide perovskite CH3NH3PbI3 in solar cells with a high power conversion efficiency exceeding 20%. However, the intrinsic as well as extrinsic instabilities of this material remain the major challenge to the commercialization of perovskite-based solar cells. Mixing halides is expected to resolve this problem. Here, we investigate the effect of chemical substitution in the position of the halogen atom on the structural, electronic, and optical properties of mixed halide perovskites CH3NH3Pb (I1-xBrx) 3 with a pseudocubic phase using the virtual crystal approximation method within density functional theory. With an increase of Br content x from 0.0 to 1.0, the lattice constant decreases in proportion to x with the function of a (x )=6.420 -0.333 x (Å), while the band gap and the exciton binding energy increase with the quadratic function of Eg(x ) =1.542 +0.374 x +0.185 x2 (eV) and the linear function of Eb(x ) =0.045 +0.057 x (eV), respectively. The photoabsorption coefficients are also calculated, showing a blueshift of the absorption onsets for higher Br contents. We calculate the phase decomposition energy of these materials and analyze the electronic charge density difference to estimate the material stability. Based on the calculated results, we suggest that the best match between efficiency and stability can be achieved at x ≈0.2 in CH3NH3Pb (I1-xBrx) 3 perovskites.

Quasi-one-dimensional arrangement of silver nanoparticles templated by cellulose microfibrils.

PubMed

Wu, Min; Kuga, Shigenori; Huang, Yong

2008-09-16

We demonstrate a simple, facile approach to the deposition of silver nanoparticles on the surface of cellulose microfibrils with a quasi-one-dimensional arrangement. The process involves the generation of aldehyde groups by oxidizing the surface of cellulose microfibrils and then the assembly of silver nanoparticles on the surface by means of the silver mirror reaction. The linear nature of the microfibrils and the relatively uniform surface chemical modification result in a uniform linear distribution of silver particles along the microfibrils. The effects of various reaction parameters, such as the reaction time for the reduction process and employed starting materials, have been investigated by transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy. Additionally, the products were examined for their electric current-voltage characteristics, the results showing that these materials had an electric conductivity of approximately 5 S/cm, being different from either the oxidated cellulose or bulk silver materials by many orders of magnitude.

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sutter-Fella, Carolin M.; Li, Yanbo; Cefarin, Nicola

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH 3NH 3I) and methylammonium bromide (CH 3NH 3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH 3NH 3PbX 3 with X = I, Br, Cl and their mixture) filmsmore » with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH 3NH 3PbI 3-xBr x by exposing the substrate to vapors of a mixture of CH 3NH 3I and CH 3NH 3Br at reduced pressure and 120 °C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH 3NH 3PbI 3-xBr x with 0 ≤ x ≤ 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV ≤ E g ≤ 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH 3NH 3PbI 3-xCl x. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.« less

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films

DOE PAGES

Sutter-Fella, Carolin M.; Li, Yanbo; Cefarin, Nicola; ...

2017-09-08

Organo-lead halide perovskites have recently attracted great interest for potential applications in thin-film photovoltaics and optoelectronics. Herein, we present a protocol for the fabrication of this material via the low-pressure vapor assisted solution process (LP-VASP) method, which yields ~19% power conversion efficiency in planar heterojunction perovskite solar cells. First, we report the synthesis of methylammonium iodide (CH 3NH 3I) and methylammonium bromide (CH 3NH 3Br) from methylamine and the corresponding halide acid (HI or HBr). Then, we describe the fabrication of pinhole-free, continuous methylammonium-lead halide perovskite (CH 3NH 3PbX 3 with X = I, Br, Cl and their mixture) filmsmore » with the LP-VASP. This process is based on two steps: i) spin-coating of a homogenous layer of lead halide precursor onto a substrate, and ii) conversion of this layer to CH 3NH 3PbI 3-xBr x by exposing the substrate to vapors of a mixture of CH 3NH 3I and CH 3NH 3Br at reduced pressure and 120 °C. Through slow diffusion of the methylammonium halide vapor into the lead halide precursor, we achieve slow and controlled growth of a continuous, pinhole-free perovskite film. The LP-VASP allows synthetic access to the full halide composition space in CH 3NH 3PbI 3-xBr x with 0 ≤ x ≤ 3. Depending on the composition of the vapor phase, the bandgap can be tuned between 1.6 eV ≤ E g ≤ 2.3 eV. In addition, by varying the composition of the halide precursor and of the vapor phase, we can also obtain CH 3NH 3PbI 3-xCl x. Films obtained from the LP-VASP are reproducible, phase pure as confirmed by X-ray diffraction measurements, and show high photoluminescence quantum yield. The process does not require the use of a glovebox.« less

Revealing the ultrafast charge carrier dynamics in organo metal halide perovskite solar cell materials using time resolved THz spectroscopy

NASA Astrophysics Data System (ADS)

Ponseca, C. S., Jr.; Sundström, V.

2016-03-01

Ultrafast charge carrier dynamics in organo metal halide perovskite has been probed using time resolved terahertz (THz) spectroscopy (TRTS). Current literature on its early time characteristics is unanimous: sub-ps charge carrier generation, highly mobile charges and very slow recombination rationalizing the exceptionally high power conversion efficiency for a solution processed solar cell material. Electron injection from MAPbI3 to nanoparticles (NP) of TiO2 is found to be sub-ps while Al2O3 NPs do not alter charge dynamics. Charge transfer to organic electrodes, Spiro-OMeTAD and PCBM, is sub-ps and few hundreds of ps respectively, which is influenced by the alignment of energy bands. It is surmised that minimizing defects/trap states is key in optimizing charge carrier extraction from these materials.

Recent Progress in Single‐Crystalline Perovskite Research Including Crystal Preparation, Property Evaluation, and Applications

PubMed Central

Liu, Yucheng

2017-01-01

Abstract Organic–inorganic lead halide perovskites are promising optoelectronic materials resulting from their significant light absorption properties and unique long carrier dynamics, such as a long carrier lifetime, carrier diffusion length, and high carrier mobility. These advantageous properties have allowed for the utilization of lead halide perovskite materials in solar cells, LEDs, photodetectors, lasers, etc. To further explore their potential, intrinsic properties should be thoroughly investigated. Single crystals with few defects are the best candidates to disclose a variety of interesting and important properties of these materials, ultimately, showing the increased importance of single‐crystalline perovskite research. In this review, recent progress on the crystallization, investigation, and primary device applications of single‐crystalline perovskites are summarized and analyzed. Further improvements in device design and preparation are also discussed. PMID:29375973

Theoretical Considerations for Improving the Pulse Power of a Battery through the Addition of a Second Electrochemically Active Material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knehr, K. W.; West, Alan C.

Here, porous electrode theory is used to conduct case studies for when the addition of a second electrochemically active material can improve the pulse-power performance of an electrode. Case studies are conducted for the positive electrode of a sodium metal-halide battery and the graphite negative electrode of a lithium “rocking chair” battery. The replacement of a fraction of the nickel chloride capacity with iron chloride in a sodium metal-halide electrode and the replacement of a fraction of the graphite capacity with carbon black in a lithium-ion negative electrode were both predicted to increase the maximum pulse power by up tomore » 40%. In general, whether or not a second electrochemically active material increases the pulse power depends on the relative importance of ohmic-to-charge transfer resistances within the porous structure, the capacity fraction of the second electrochemically active material, and the kinetic and thermodynamic parameters of the two active materials.« less

Theoretical Considerations for Improving the Pulse Power of a Battery through the Addition of a Second Electrochemically Active Material

DOE PAGES

Knehr, K. W.; West, Alan C.

2016-05-26

Here, porous electrode theory is used to conduct case studies for when the addition of a second electrochemically active material can improve the pulse-power performance of an electrode. Case studies are conducted for the positive electrode of a sodium metal-halide battery and the graphite negative electrode of a lithium “rocking chair” battery. The replacement of a fraction of the nickel chloride capacity with iron chloride in a sodium metal-halide electrode and the replacement of a fraction of the graphite capacity with carbon black in a lithium-ion negative electrode were both predicted to increase the maximum pulse power by up tomore » 40%. In general, whether or not a second electrochemically active material increases the pulse power depends on the relative importance of ohmic-to-charge transfer resistances within the porous structure, the capacity fraction of the second electrochemically active material, and the kinetic and thermodynamic parameters of the two active materials.« less

Interfacial and Surface Science | Materials Science | NREL

Science.gov Websites

-flight SIMS (TOF-SIMS) provides surface spectroscopy of both inorganic and organic materials, and is Chamber This tool enables deposition of inorganic chalcogenides and for basic material and device studies lead halide perovskites and semiconductor quantum dots. Contact: Craig Perkins | Email | 303-384-6659

Sorption of Triangular Silver Nanoplates on Polyurethane Foam

NASA Astrophysics Data System (ADS)

Furletov, A. A.; Apyari, V. V.; Garshev, A. V.; Volkov, P. A.; Tolmacheva, V. V.; Dmitrienko, S. G.

2018-02-01

The sorption of triangular silver nanoplates on polyurethane foam is investigated as a procedure for creating a nanocomposite sensing material for subsequent use in optical means of chemical analysis. Triangular silver nanoplates are synthesized and characterized, and a simple sorption technique for the formation of a composite material based on these nanoplates is proposed.

Alternatives to silver amalgam and resin composite in pediatric dentistry.

PubMed

Croll, T P

1998-11-01

Silver amalgam has become a less attractive dental restorative material for restoration of primary teeth. After many decades of scientific and nonscientific controversy, use of silver amalgam for primary teeth is waning, not because of its mercury content but because dentistry has come up with more suitable materials. This article reviews the development and use of glass-ionomer silver-cermet cements, resin-modified glass-ionomer cements, and polyacid-modified resin composites (compomers) for restoration of primary teeth.

Planetary atmospheres program

NASA Technical Reports Server (NTRS)

1982-01-01

Non-solar compositional models of the troposphere of Jupiter, halide cloud condensation and volatile element inventories on Venus, and shock-wave processing of interstellar cloud materials are discussed.

RESEARCH ACTIVITIES IN THE FIELD OF MATERIALS SCIENCE.

DTIC Science & Technology

MAGNETIC RESONANCE, COMPLEX COMPOUNDS, CRYSTAL STRUCTURE, ELECTROCHEMISTRY, CHEMILUMINESCENCE, PHOTOCHEMICAL REACTIONS, PHOSPHORUS HETEROCYCLIC COMPOUNDS...RADIATION CHEMISTRY, POLYMERS, ROCK, SUPERCONDUCTORS, POSITRONS , DAMAGE, RADIATION EFFECTS, HALIDES

Infrared Dielectric Screening Determines the Low Exciton Binding Energy of Metal-Halide Perovskites.

PubMed

Umari, Paolo; Mosconi, Edoardo; De Angelis, Filippo

2018-02-01

The performance of lead-halide perovskites in optoelectronic devices is due to a unique combination of factors, including highly efficient generation, transport, and collection of photogenerated charge carriers. The mechanism behind efficient charge generation in lead-halide perovskites is still largely unknown. Here, we investigate the factors that influence the exciton binding energy (E b ) in a series of metal-halide perovskites using accurate first-principles calculations based on solution of the Bethe-Salpeter equation, coupled to ab initio molecular dynamics simulations. We find that E b is strongly modulated by screening from low-energy phonons, which account for a factor ∼2 E b reduction, while dynamic disorder and rotational motion of the organic cations play a minor role. We calculate E b = 15 meV for MAPbI 3 , in excellent agreement with recent experimental estimates. We then explore how different material combinations (e.g., replacing Pb → Pb:Sn→ Sn; and MA → FA → Cs) may lead to different E b values and highlight the mechanisms underlying E b tuning.

APPLICATION OF VACUUM SALT DISTILLATION TECHNOLOGY FOR THE REMOVAL OF FLUORIDE AND CHLORIDE FROM LEGACY FISSILE MATERIALS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierce, R.; Peters, T.

2011-11-01

Between September 2009 and January 2011, the Savannah River National Laboratory (SRNL) and the Savannah River Site (SRS) HB-Line Facility designed, developed, tested, and successfully deployed a production-scale system for the distillation of sodium chloride (NaCl) and potassium chloride (KCl) from plutonium oxide (PuO{sub 2}). Subsequent efforts adapted the vacuum salt distillation (VSD) technology for the removal of chloride and fluoride from less-volatile halide salts at the same process temperature and vacuum. Calcium chloride (CaCl{sub 2}), calcium fluoride (CaF{sub 2}), and plutonium fluoride (PuF{sub 3}) were of particular concern. To enable the use of the same operating conditions for themore » distillation process, SRNL employed in situ exchange reactions to convert the less-volatile halide salts to compounds that facilitated the distillation of halide without removal of plutonium. SRNL demonstrated the removal of halide from CaCl{sub 2}, CaF{sub 2} and PuF{sub 3} below 1000 C using VSD technology.« less

Reversible photo-induced trap formation in mixed-halide hybrid perovskites for photovoltaics.

PubMed

Hoke, Eric T; Slotcavage, Daniel J; Dohner, Emma R; Bowring, Andrea R; Karunadasa, Hemamala I; McGehee, Michael D

2015-01-01

We report on reversible, light-induced transformations in (CH 3 NH 3 )Pb(Br x I 1- x ) 3 . Photoluminescence (PL) spectra of these perovskites develop a new, red-shifted peak at 1.68 eV that grows in intensity under constant, 1-sun illumination in less than a minute. This is accompanied by an increase in sub-bandgap absorption at ∼1.7 eV, indicating the formation of luminescent trap states. Light soaking causes a splitting of X-ray diffraction (XRD) peaks, suggesting segregation into two crystalline phases. Surprisingly, these photo-induced changes are fully reversible; the XRD patterns and the PL and absorption spectra revert to their initial states after the materials are left for a few minutes in the dark. We speculate that photoexcitation may cause halide segregation into iodide-rich minority and bromide-enriched majority domains, the former acting as a recombination center trap. This instability may limit achievable voltages from some mixed-halide perovskite solar cells and could have implications for the photostability of halide perovskites used in optoelectronics.

Steric engineering of metal-halide perovskites with tunable optical band gaps

NASA Astrophysics Data System (ADS)

Filip, Marina R.; Eperon, Giles E.; Snaith, Henry J.; Giustino, Feliciano

2014-12-01

Owing to their high energy-conversion efficiency and inexpensive fabrication routes, solar cells based on metal-organic halide perovskites have rapidly gained prominence as a disruptive technology. An attractive feature of perovskite absorbers is the possibility of tailoring their properties by changing the elemental composition through the chemical precursors. In this context, rational in silico design represents a powerful tool for mapping the vast materials landscape and accelerating discovery. Here we show that the optical band gap of metal-halide perovskites, a key design parameter for solar cells, strongly correlates with a simple structural feature, the largest metal-halide-metal bond angle. Using this descriptor we suggest continuous tunability of the optical gap from the mid-infrared to the visible. Precise band gap engineering is achieved by controlling the bond angles through the steric size of the molecular cation. On the basis of these design principles we predict novel low-gap perovskites for optimum photovoltaic efficiency, and we demonstrate the concept of band gap modulation by synthesising and characterising novel mixed-cation perovskites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slavney, Adam H.; Leppert, Linn; Bartesaghi, Davide

In this study, halide double perovskites have recently been developed as less toxic analogs of the lead perovskite solar-cell absorbers APbX 3 (A = monovalent cation; X = Br or I). However, all known halide double perovskites have large bandgaps that afford weak visible-light absorption. The first halide double perovskite evaluated as an absorber, Cs 2AgBiBr 6 (1), has a bandgap of 1.95 eV. Here, we show that dilute alloying decreases 1’s bandgap by ca. 0.5 eV. Importantly, time-resolved photoconductivity measurements reveal long-lived carriers with microsecond lifetimes in the alloyed material, which is very promising for photovoltaic applications. The alloyedmore » perovskite described herein is the first double perovskite to show comparable bandgap energy and carrier lifetime to those of (CH 3NH 3)PbI 3. By describing how energy- and symmetry-matched impurity orbitals, at low concentrations, dramatically alter 1’s band edges, we open a potential pathway for the large and diverse family of halide double perovskites to compete with APbX 3 absorbers.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Yongping; Zhu, Haiming; Schrader, Alex W.

The excellent intrinsic optoelectronic properties of methylammonium lead halide perovskites (MAPbX 3, X = Br, I), such as high photoluminescence quantum efficiency, long carrier lifetime, and high gain coupled with the facile solution growth of nanowires make them promising new materials for ultralow-threshold nanowire lasers. However, their photo and thermal stabilities need to be improved for practical applications. Herein, we report a low-temperature solution growth of single crystal nanowires of formamidinium lead halide perovskites (FAPbX 3) that feature red-shifted emission and better thermal stability compared to MAPbX 3. We demonstrate optically pumped room-temperature near-infrared (~820 nm) and green lasing (~560more » nm) from FAPbI 3 (and MABr-stabilized FAPbI 3) and FAPbBr 3 nanowires with low lasing thresholds of several microjoules per square centimeter and high quality factors of about 1500–2300. More remarkably, the FAPbI 3 and MABr-stabilized FAPbI 3 nanowires display durable room-temperature lasing under ~10 8 shots of sustained illumination of 402 nm pulsed laser excitation (150 fs, 250 kHz), substantially exceeding the stability of MAPbI 3 (~10 7 laser shots). We further demonstrate tunable nanowire lasers in wider wavelength region from FA-based lead halide perovskite alloys (FA,MA)PbI 3 and (FA,MA)Pb(I,Br) 3 through cation and anion substitutions. The results suggest that formamidinium lead halide perovskite nanostructures could be more promising and stable materials for the development of light-emitting diodes and continuous-wave lasers.« less

Hydrostatic extrusion of Cu-Ag melt spun ribbon

DOEpatents

Hill, M.A.; Bingert, J.F.; Bingert, S.A.; Thoma, D.J.

1998-09-08

The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process. 5 figs.

Hydrostatic extrusion of Cu-Ag melt spun ribbon

DOEpatents

Hill, Mary Ann; Bingert, John F.; Bingert, Sherri A.; Thoma, Dan J.

1998-01-01

The present invention provides a method of producing high-strength and high-conductance copper and silver materials comprising the steps of combining a predetermined ratio of the copper with the silver to produce a composite material, and melt spinning the composite material to produce a ribbon of copper and silver. The ribbon of copper and silver is heated in a hydrogen atmosphere, and thereafter die pressed into a slug. The slug then is placed into a high-purity copper vessel and the vessel is sealed with an electron beam. The vessel and slug then are extruded into wire form using a cold hydrostatic extrusion process.

Electronic Properties of Free-Standing Surfactant-Capped Lead Halide Perovskite Nanocrystals Isolated in Vacuo.

PubMed

Milosavljevic, Aleksandar R; Bozanic, Dusan; Sadhu, Subha; Vukmirovic, Nenad; Dojcilovic, Radovan; Sapkota, Pitambar; Huang, Weixin; Bozek, John D; Nicolas, Christophe; Nahon, Laurent; Ptasinska, Sylwia

2018-06-14

We report an investigation of lead halide perovskite CH3NH3PbBr3 nanocrystals and associated ligand molecules, by combining several different state-of-the-art experimental techniques, including synchrotron radiation based XPS and VUV PES of free-standing nanocrystals isolated in vacuum. By using this novel approach for perovskite materials we could directly obtain a complete band alignment to vacuum of both CH3NH3PbBr3 nanocrystals and the ligands widely used in their preparation. We discuss possible influence of the ligand molecules to apparent perovskite properties, and we compare the electronic properties of nanocrystals to that of bulk material. The experimental results were supported by DFT calculations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosales, Bryan A.; Hanrahan, Michael P.; Boote, Brett W.

Hybrid lead perovskites containing a mixture of organic and inorganic cations and anions have lead to solar cell devices with better performance and stability than their single halide analogs. Here, 207Pb solid-state nuclear magnetic resonance and single particle photoluminescence spectroscopies show that the structure and composition of mixed-halide and—likely—other hybrid lead perovskites is much more complex than previously thought and is highly dependent on their synthesis. While a majority of reports in the area focus on the construction of photovoltaic devices, this perspective focuses instead on achieving a better understanding of the fundamental chemistry and photophysics of these materials, asmore » this will aid not only in constructing improved devices, but also in generating new uses for these unique materials.« less

Perspective: Theory and simulation of hybrid halide perovskites

PubMed Central

Jung, Young-Kwang

2017-01-01

Organic-inorganic halide perovskites present a number of challenges for first-principles atomistic materials modeling. Such “plastic crystals” feature dynamic processes across multiple length and time scales. These include the following: (i) transport of slow ions and fast electrons; (ii) highly anharmonic lattice dynamics with short phonon lifetimes; (iii) local symmetry breaking of the average crystallographic space group; (iv) strong relativistic (spin-orbit coupling) effects on the electronic band structure; and (v) thermodynamic metastability and rapid chemical breakdown. These issues, which affect the operation of solar cells, are outlined in this perspective. We also discuss general guidelines for performing quantitative and predictive simulations of these materials, which are relevant to metal-organic frameworks and other hybrid semiconducting, dielectric and ferroelectric compounds. PMID:29166078

Positive electrode current collector for liquid metal cells

DOEpatents

Shimotake, Hiroshi; Bartholme, Louis G.

1984-01-01

A current collector for the positive electrode of an electrochemical cell with a positive electrode including a sulfide. The cell also has a negative electrode and a molten salt electrolyte including halides of a metal selected from the alkali metals and the alkaline earth metals in contact with both the positive and negative electrodes. The current collector has a base metal of copper, silver, gold, aluminum or alloys thereof with a coating thereon of iron, nickel, chromium or alloys thereof. The current collector when subjected to cell voltage forms a sulfur-containing compound on the surface thereby substantially protecting the current collector from further attack by sulfur ions during cell operation. Both electroless and electrolytic processes may be used to deposit coatings.

Development of High Sensitivity Nuclear Emulsion and Fine Grained Emulsion

NASA Astrophysics Data System (ADS)

Kawahara, H.; Asada, T.; Naka, T.; Naganawa, N.; Kuwabara, K.; Nakamura, M.

2014-08-01

Nuclear emulsion is a particle detector having high spacial resolution and angular resolution. It became useful for large statistics experiment thanks to the development of automatic scanning system. In 2010, a facility for emulsion production was introduced and R&D of nuclear emulsion began at Nagoya university. In this paper, we present results of development of the high sensitivity emulsion and fine grained emulsion for dark matter search experiment. Improvement of sensitivity is achieved by raising density of silver halide crystals and doping well-adjusted amount of chemicals. Production of fine grained emulsion was difficult because of unexpected crystal condensation. By mixing polyvinyl alcohol (PVA) to gelatin as a binder, we succeeded in making a stable fine grained emulsion.

LCD real-time mask technique for fabrication of arbitrarily shaped microstructure

NASA Astrophysics Data System (ADS)

Peng, Qinjun; Guo, Yongkang; Chen, Bo; Du, Jinglei; Xiang, Jinshan; Cui, Zheng

2002-04-01

A new technique to fabricate arbitrarily shaped microstructures by using LCD (liquid crystal display) real- time mask is reported in this paper. Its principle and design method are explained. Based on partial coherent imaging theory, the process to fabricate micro-axicon array and zigzag grating has been simulated. The experiment using a color LCD as real-time mask has been set up. Micro-axicon array and zigzag grating has been fabricated by the LCD real-time mask technique. The 3D surface relief structures were made on pan chromatic silver-halide sensitized gelatin (Kodak-131) with trypsinase etching. The pitch size of zigzag grating is 46.26micrometers . The caliber of axicon is 118.7micrometers , and the etching depth is 1.332micrometers .

Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

PubMed

Chen, Shaojiang; Popovich, John; Iannuzo, Natalie; Haydel, Shelley E; Seo, Dong-Kyun

2017-11-15

As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous antibiotic-resistant bacteria.

Local Polar Fluctuations in Lead Halide Perovskite Crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaffe, Omer; Guo, Yinsheng; Tan, Liang Z.

2017-03-01

Hybrid lead-halide perovskites have emerged as an excellent class of photovoltaic materials. Recent reports suggest that the organic molecular cation is responsible for local polar fluctuations that inhibit carrier recombination. We combine low-frequency Raman scattering with first-principles molecular dynamics (MD) to study the fundamental nature of these local polar fluctuations. Our observations of a strong central peak in the cubic phase of both hybrid (CH3NH3PbBr3) and all-inorganic (CsPbBr3) leadhalide perovskites show that anharmonic, local polar fluctuations are intrinsic to the general lead-halide perovskite structure, and not unique to the dipolar organic cation. MD simulations indicate that head-tohead Cs motion coupledmore » to Br face expansion, occurring on a few hundred femtosecond time scale, drives the local polar fluctuations in CsPbBr3.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dou, Letian; Lai, Minliang; Kley, Christopher S.

Halide perovskites are promising semiconductor materials for solution-processed optoelectronic devices. Their strong ionic bonding nature results in highly dynamic crystal lattices, inherently allowing rapid ion exchange at the solid–vapor and solid–liquid interface. In this paper, we show that the anion-exchange chemistry can be precisely controlled in single-crystalline halide perovskite nanomaterials when combined with nanofabrication techniques. We demonstrate spatially resolved multicolor CsPbX 3 (X = Cl, Br, I, or alloy of two halides) nanowire heterojunctions with a pixel size down to 500 nm with the photoluminescence tunable over the entire visible spectrum. In addition, the heterojunctions show distinct electronic states acrossmore » the interface, as revealed by Kelvin probe force microscopy. Finally, these perovskite heterojunctions represent key building blocks for high-resolution multicolor displays beyond current state-of-the-art technology as well as high-density diode/transistor arrays.« less

Exploring Anomalous Polarization Dynamics in Organometallic Halide Perovskites

DOE PAGES

Ahmadi, Mahshid; Collins, Liam; Puretzky, Alexander; ...

2018-01-22

Organometallic halide perovskites (OMHPs) have attracted broad attention as prospective materials for optoelectronic applications. Among the many anomalous properties of these materials, of special interest are the ferroelectric properties including both classical and relaxor-like components, as a potential origin of slow dynamics, field enhancement, and anomalous mobilities. Here, ferroelectric properties of the three representative OMHPs are explored, including FAPb xSn 1–xI 3 (x = 0, x = 0.85) and FA 0.85MA 0.15PbI 3 using band excitation piezoresponse force microscopy and contact mode Kelvin probe force microscopy, providing insight into long- and short-range dipole and charge dynamics in these materials andmore » probing ferroelectric density of states. Furthermore, second-harmonic generation in thin films of OMHPs is observed, providing a direct information on the noncentrosymmetric polarization in such materials. Overall, the data provide strong evidence for the presence of ferroelectric domains in these systems; however, the domain dynamics is suppressed by fast ion dynamics. These materials hence present the limit of ferroelectric materials with spontaneous polarization dynamically screened by ionic and electronic carriers.« less

Exploring Anomalous Polarization Dynamics in Organometallic Halide Perovskites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmadi, Mahshid; Collins, Liam; Puretzky, Alexander

Organometallic halide perovskites (OMHPs) have attracted broad attention as prospective materials for optoelectronic applications. Among the many anomalous properties of these materials, of special interest are the ferroelectric properties including both classical and relaxor-like components, as a potential origin of slow dynamics, field enhancement, and anomalous mobilities. Here, ferroelectric properties of the three representative OMHPs are explored, including FAPb xSn 1–xI 3 (x = 0, x = 0.85) and FA 0.85MA 0.15PbI 3 using band excitation piezoresponse force microscopy and contact mode Kelvin probe force microscopy, providing insight into long- and short-range dipole and charge dynamics in these materials andmore » probing ferroelectric density of states. Furthermore, second-harmonic generation in thin films of OMHPs is observed, providing a direct information on the noncentrosymmetric polarization in such materials. Overall, the data provide strong evidence for the presence of ferroelectric domains in these systems; however, the domain dynamics is suppressed by fast ion dynamics. These materials hence present the limit of ferroelectric materials with spontaneous polarization dynamically screened by ionic and electronic carriers.« less

Effects of materials surface preparation for use in spacecraft potable water storage tanks

NASA Astrophysics Data System (ADS)

Wallace, William T.; Wallace, Sarah L.; Loh, Leslie J.; Kuo, C. K. Mike; Hudson, Edgar K.; Marlar, Tyler J.; Gazda, Daniel B.

2017-12-01

Maintaining a safe supply of potable water is of utmost importance when preparing for long-duration spaceflight missions, with the minimization of microbial growth being one major aspect. While biocides, such as ionic silver, historically have been used for microbial control in spaceflight, their effectiveness is sometimes limited due to surface reactions with the materials of the storage containers that reduce their concentrations below the effective range. For the Multi-Purpose Crew Vehicle, the primary wetted materials of the water storage system are stainless steel and a titanium alloy, and ionic silver has been chosen to serve as the biocide. As an attempt to understand what processes might reduce the known losses of silver, different treatment processes were attempted and samples of the wetted materials were tested, individually and together, to determine the relative loss of biocide under representative surface area-to-volume ratios. The results of testing presented here showed that the materials could be treated by a nitric acid rinse or a high-concentration silver spike to reduce the loss of silver and bacterial growth. It was also found that the minimum biocidal concentration could be maintained for over 28 days. These results have pointed to approaches that could be used to successfully maintain silver in spacecraft water systems for long-duration missions.

Sampling for silver nanoparticles in aqueous media using a rotating disk electrode: evidence for selective sampling of silver nanoparticles in the presence of ionic silver.

PubMed

Steinberg, Spencer; Hodge, Vernon; Schumacher, Brian; Sovocool, Wayne

2017-03-01

Amendment of a carbon paste electrode consisting of graphite and Nujol®, with a variety of organic and inorganic materials, allows direct adsorption of silver nanoparticles (AgNPs) from aqueous solution in either open or close circuit modes. The adsorbed AgNPs are detected by stripping voltammetry. Detection limits of less than 1 ppb Ag are achievable with a rotating disk system. More than one silver peak was apparent in many of the stripping voltammograms. The appearance of multiple peaks could be due to different species of silver formed upon stripping or variation in the state of aggregation or size of nanoparticles. With most of these packing materials, dissolved Ag + was also extracted from aqueous solution, but, with a packing material made with Fe(II,III) oxide nanoparticles, only AgNPs were extracted. Therefore, it is the best candidate for determination of metallic AgNPs in aqueous environmental samples without interference from Ag + .

In-Situ Silver Acetylide Silver Nitrate Explosive Deposition Measurements Using X-Ray Fluorescence.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Covert, Timothy Todd

2014-09-01

The Light Initiated High Explosive facility utilized a spray deposited coating of silver acetylide - silver nitrate explosive to impart a mechanical shock into targets of interest. A diagnostic was required to measure the explosive deposition in - situ. An X - ray fluorescence spectrometer was deployed at the facility. A measurement methodology was developed to measure the explosive quantity with sufficient accuracy. Through the use of a tin reference material under the silver based explosive, a field calibration relationship has been developed with a standard deviation of 3.2 % . The effect of the inserted tin material into themore » experiment configuration has been explored.« less

The Oxidation State of Europium in Halide Glasses

PubMed Central

Weber, J.K.R.; Vu, M.; Paßlick, C.; Schweizer, S.; Brown, D.E.; Johnson, C.E.; Johnson, J.A.

2012-01-01

The luminescent properties of divalent europium ions can be exploited to produce storage phosphors for x-ray imaging applications. The relatively high cost and limited availability of divalent europium halides makes it desirable to synthesize them from the readily available trivalent salts. In this work, samples of pure EuCl3 and fluoride glass melts doped with EuCl3 were processed at 700-800 °C in an inert atmosphere furnace. The Eu oxidation state in the resulting materials was determined using fluorescence and Mössbauer spectroscopy. Heat treatment of pure EuCl3 for 10 minutes at 710 °C resulted in a material comprising approximately equal amounts of Eu2+ and Eu3+. Glasses made using mixtures of EuCl2 and EuCl3 in the starting material contained both oxidation states. This paper describes the sample preparation and analysis and discusses the results in the context of chemical equilibria in the melts. PMID:22101252

Biexciton Auger Recombination Differs in Hybrid and Inorganic Halide Perovskite Quantum Dots.

PubMed

Eperon, Giles E; Jedlicka, Erin; Ginger, David S

2018-01-04

We use time-resolved photoluminescence measurements to determine the biexciton Auger recombination rate in both hybrid organic-inorganic and fully inorganic halide perovskite nanocrystals as a function of nanocrystal volume. We find that the volume scaling of the biexciton Auger rate in the hybrid perovskites, containing a polar organic A-site cation, is significantly shallower than in the fully inorganic Cs-based nanocrystals. As the nanocrystals become smaller, the Auger rate in the hybrid nanocrystals increases even less than expected, compared to the fully inorganic nanocrystals, which already show a shallower volume dependence than other material systems such as chalcogenide quantum dots. This finding suggests there may be differences in the strength of Coulombic interactions between the fully inorganic and hybrid perovskites, which may prove to be crucial in selecting materials to obtain the highest performing devices in the future, and hints that there could be something "special" about the hybrid materials.

Perovskite-fullerene hybrid materials suppress hysteresis in planar diodes

NASA Astrophysics Data System (ADS)

Xu, Jixian; Buin, Andrei; Ip, Alexander H.; Li, Wei; Voznyy, Oleksandr; Comin, Riccardo; Yuan, Mingjian; Jeon, Seokmin; Ning, Zhijun; McDowell, Jeffrey J.; Kanjanaboos, Pongsakorn; Sun, Jon-Paul; Lan, Xinzheng; Quan, Li Na; Kim, Dong Ha; Hill, Ian G.; Maksymovych, Peter; Sargent, Edward H.

2015-05-01

Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite-PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3- antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour.

Material Innovation in Advancing Organometal Halide Perovskite Functionality.

PubMed

Zheng, Fan; Saldana-Greco, Diomedes; Liu, Shi; Rappe, Andrew M

2015-12-03

Organometal halide perovskites (OMHPs) have garnered much attention recently for their unprecedented rate of increasing power conversion efficiency (PCE), positioning them as a promising basis for the next-generation photovoltaic devices. However, the gap between the rapid increasing PCE and the incomplete understanding of the structure-property-performance relationship prevents the realization of the true potential of OMHPs. This Perspective aims to provide a concise overview of the current status of OMHP research, highlighting the unique properties of OMHPs that are critical for solar applications but still not adequately explained. Stability and performance challenges of OMHP solar cells are discussed, calling upon combined experimental and theoretical efforts to address these challenges for pioneering commercialization of OMHP solar cells. Various material innovation strategies for improving the performance and stability of OMHPs are surveyed, showing that the OMHP architecture can serve as a promising and robust platform for the design and optimization of materials with desired functionalities.

A Photoferroelectric Perovskite-Type Organometallic Halide with Exceptional Anisotropy of Bulk Photovoltaic Effects.

PubMed

Sun, Zhihua; Liu, Xitao; Khan, Tariq; Ji, Chengmin; Asghar, Muhammad Adnan; Zhao, Sangen; Li, Lina; Hong, Maochun; Luo, Junhua

2016-05-23

Perovskite-type ferroelectrics composed of organometallic halides are emerging as a promising alternative to conventional photovoltaic devices because of their unique photovoltaic effects (PVEs). A new layered perovskite-type photoferroelectric, bis(cyclohexylaminium) tetrabromo lead (1), is presented. The material exhibits an exceptional anisotropy of bulk PVEs. Upon photoexcitation, superior photovoltaic behaviors are created along its inorganic layers, which are composed of corner-sharing PbBr6 octahedra. Semiconducting activity with remarkable photoconductivity is achieved in the vertical direction, showing sizeable on/off current ratios (>10(4) ), which compete with the most active photovoltaic material CH3 NH3 PbI3 . In 1 the temperature-dependence of photovoltage coincides fairly well with that of polarization, confirming the dominant role of ferroelectricity in such highly anisotropic PVEs. This finding sheds light on bulk PVEs in ferroelectric materials, and promotes their application in optoelectronic devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ultrastable Photoelectrodes for Solar Water Splitting Based on Organic Metal Halide Perovskite Fabricated by Lift-Off Process.

PubMed

Nam, SeongSik; Mai, Cuc Thi Kim; Oh, Ilwhan

2018-05-02

Herein, we report an integrated photoelectrolysis of water employing organic metal halide (OMH) perovskite material. As generic OMH perovskite material and device architecture are highly susceptible to degradation by aqueous electrolytes, we have developed a versatile mold-cast and lift-off process to fabricate and assemble multipurpose metal encapsulation onto perovskite devices. With the metal encapsulation effectively protecting the perovskite cell and also functioning as electrocatalyst, the high-performance perovskite photoelectrodes exhibit high photovoltage and photocurrent that are effectively inherited from the original solid-state solar cell. More importantly, thus-fabricated perovskite photoelectrode demonstrates record-long unprecedented stability even at highly oxidizing potential in strong alkaline electrolyte. We expect that this versatile lift-off process can be adapted in a wide variety of photoelectrochemical devices to protect the material surfaces from corroding electrolyte and facilitate various electrochemical reactions.

Quantum Chemical Study of Rare Gas/Halide Interactions as a Model for High Energy Density Material: 2. The Interaction of Hydrogen Chloride with the Rare Gas Xenon

DTIC Science & Technology

1994-11-01

the negatively charged halide, X(-), remains scparatcd from the Rgnl(+) hole. But when the (+) holes migrate to the X(-), they rapidly form the exciplex ...Xe2.(+)X(-), releasing the exciton energy as fluorescence. The gas phase equilibrium geometry for the Xe 2C1 exciplex in the 421- state is predicted...understanding of the microscopic processes involved in formation c. the exciplex , as well as the factors determining the lifetime of the separated

Method for removing semiconductor layers from salt substrates

DOEpatents

Shuskus, Alexander J.; Cowher, Melvyn E.

1985-08-27

A method is described for removing a CVD semiconductor layer from an alkali halide salt substrate following the deposition of the semiconductor layer. The semiconductor-substrate combination is supported on a material such as tungsten which is readily wet by the molten alkali halide. The temperature of the semiconductor-substrate combination is raised to a temperature greater than the melting temperature of the substrate but less than the temperature of the semiconductor and the substrate is melted and removed from the semiconductor by capillary action of the wettable support.

Highly Efficient Broadband Yellow Phosphor Based on Zero-Dimensional Tin Mixed-Halide Perovskite.

PubMed

Zhou, Chenkun; Tian, Yu; Yuan, Zhao; Lin, Haoran; Chen, Banghao; Clark, Ronald; Dilbeck, Tristan; Zhou, Yan; Hurley, Joseph; Neu, Jennifer; Besara, Tiglet; Siegrist, Theo; Djurovich, Peter; Ma, Biwu

2017-12-27

Organic-inorganic hybrid metal halide perovskites have emerged as a highly promising class of light emitters, which can be used as phosphors for optically pumped white light-emitting diodes (WLEDs). By controlling the structural dimensionality, metal halide perovskites can exhibit tunable narrow and broadband emissions from the free-exciton and self-trapped excited states, respectively. Here, we report a highly efficient broadband yellow light emitter based on zero-dimensional tin mixed-halide perovskite (C 4 N 2 H 14 Br) 4 SnBr x I 6-x (x = 3). This rare-earth-free ionically bonded crystalline material possesses a perfect host-dopant structure, in which the light-emitting metal halide species (SnBr x I 6-x 4- , x = 3) are completely isolated from each other and embedded in the wide band gap organic matrix composed of C 4 N 2 H 14 Br - . The strongly Stokes-shifted broadband yellow emission that peaked at 582 nm from this phosphor, which is a result of excited state structural reorganization, has an extremely large full width at half-maximum of 126 nm and a high photoluminescence quantum efficiency of ∼85% at room temperature. UV-pumped WLEDs fabricated using this yellow emitter together with a commercial europium-doped barium magnesium aluminate blue phosphor (BaMgAl 10 O 17 :Eu 2+ ) can exhibit high color rendering indexes of up to 85.

Thermodynamic origin of instability in hybrid halide perovskites

PubMed Central

Tenuta, E.; Zheng, C.; Rubel, O.

2016-01-01

Degradation of hybrid halide perovskites under the influence of environmental factors impairs future prospects of using these materials as absorbers in solar cells. First principle calculations can be used as a guideline in search of new materials, provided we can rely on their predictive capabilities. We show that the instability of perovskites can be captured using ab initio total energy calculations for reactants and products augmented with additional thermodynamic data to account for finite temperature effects. Calculations suggest that the instability of CH3NH3PbI3 in moist environment is linked to the aqueous solubility of the CH3NH3I salt, thus making other perovskite materials with soluble decomposition products prone to degradation. Properties of NH3OHPbI3, NH3NH2PbI3, PH4PbI3, SbH4PbI3, CsPbBr3, and a new hypothetical SF3PbI3 perovskite are studied in the search for alternative solar cell absorber materials with enhanced chemical stability. PMID:27883032

Quantitative determination of the salinity of seawater droplet in 10-6 to 10-10 gram

NASA Astrophysics Data System (ADS)

Qian, Zhengxu; Peng, Fangying

1990-09-01

The rate of evaporation of seawater droplets in the air-sea boundary layer can be estimated by its salinity change compared to the sea surface salinity. A micro-chemical method based on Farlow (1954) is developed for quantitative determination of the salinity of an individual droplet without the error due to further evaporation after sampling. A halide ion-sensitive sampling surface is prepared by colloidally dispersing brown silver dichromate into the gelatin layer of a commercially available film. The reaction of soluble chlorides with the silver salt leaves a clear white halo with diameter a on the brown film to reveal the volume of the droplet. After the film is developed in a water vapor saturated atmosphere, the halo grows to diameter d with the original as the embryo to indicate the quantity of chloride ion involved in the action. The ratio of d/(a1.5) is a function of the salinity of the droplet. The method can be used to determine the salinity of seawater droplet of 10-6 to 10-10 gram. Details of the principle and preparation, and calibration of the reagent film, are presented.

Digital image improvement by adding noise: an example by a professional photographer

NASA Astrophysics Data System (ADS)

Kurihara, Takehito; Manabe, Yoshitsugu; Aoki, Naokazu; Kobayashi, Hiroyuki

2008-01-01

To overcome shortcomings of digital image, or to reproduce grain of traditional silver halide photographs, some photographers add noise (grain) to digital image. In an effort to find a factor of preferable noise, we analyzed how a professional photographer introduces noise into B&W digital images and found two noticeable characteristics: 1) there is more noise in mid-tones, gradually decreasing in highlights and shadows toward the ends of tonal range, and 2) histograms in highlights are skewed toward shadows and vice versa, while almost symmetrical in mid-tones. Next, we examined whether the professional's noise could be reproduced. The symmetrical histograms were approximated by Gaussian distribution and skewed ones by chi-square distribution. The images on which the noise was reproduced were judged by the professional himself to be satisfactory enough. As the professional said he added the noise so that "it looked like the grain of B&W gelatin silver photographs," we compared the two kinds of noise and found they have in common: 1) more noise in mid-tones but almost none in brightest highlights and deepest shadows, and 2) asymmetrical histograms in highlights and shadows. We think these common characteristics might be one condition for "good" noise.

Spatial imaging in color and HDR: prometheus unchained

NASA Astrophysics Data System (ADS)

McCann, John J.

2013-03-01

The Human Vision and Electronic Imaging Conferences (HVEI) at the IS and T/SPIE Electronic Imaging meetings have brought together research in the fundamentals of both vision and digital technology. This conference has incorporated many color disciplines that have contributed to the theory and practice of today's imaging: color constancy, models of vision, digital output, high-dynamic-range imaging, and the understanding of perceptual mechanisms. Before digital imaging, silver halide color was a pixel-based mechanism. Color films are closely tied to colorimetry, the science of matching pixels in a black surround. The quanta catch of the sensitized silver salts determines the amount of colored dyes in the final print. The rapid expansion of digital imaging over the past 25 years has eliminated the limitations of using small local regions in forming images. Spatial interactions can now generate images more like vision. Since the 1950's, neurophysiology has shown that post-receptor neural processing is based on spatial interactions. These results reinforced the findings of 19th century experimental psychology. This paper reviews the role of HVEI in color, emphasizing the interaction of research on vision and the new algorithms and processes made possible by electronic imaging.

Electroless silver coating of rod-like glass particles.

PubMed

Moon, Jee Hyun; Kim, Kyung Hwan; Choi, Hyung Wook; Lee, Sang Wha; Park, Sang Joon

2008-09-01

An electroless silver coating of rod-like glass particles was performed and silver glass composite powders were prepared to impart electrical conductivity to these non-conducting glass particles. The low density Ag-coated glass particles may be utilized for manufacturing conducting inorganic materials for electromagnetic interference (EMI) shielding applications and the techniques for controlling the uniform thickness of silver coating can be employed in preparation of biosensor materials. For the surface pretreatment, Sn sensitization was performed and the coating powders were characterized by scanning electron microscopy (SEM), focused ion beam microscopy (FIB), and atomic force microscopy (AFM) along with the surface resistant measurements. In particular, the use of FIB technique for determining directly the Ag-coating thickness was very effective on obtaining the optimum conditions for coating. The surface sensitization and initial silver loading for electroless silver coating could be found and the uniform and smooth silver-coated layer with thickness of 46 nm was prepared at 2 mol/l of Sn and 20% silver loading.

Perovskites keep on giving

NASA Astrophysics Data System (ADS)

2018-05-01

Whether you like exploring the mysteries of light-matter interactions, playing with a versatile chemical platform, or developing the most efficient devices, metal halide perovskites could be the materials for you.

Interface Engineering and Morphology Study of Thin Film Organic-Inorganic Halide Perovskite Optoelectronic Devices

NASA Astrophysics Data System (ADS)

Meng, Lei

Solar energy harvesting through photovoltaic conversion has gained great attention as a sustainable and environmentally friendly solution to meet the rapidly increasing global energy demand. Currently, the high cost of solar-cell technology limits its widespread use. This situation has generated considerable interest in developing alternative solar-cell technologies that reduce cost through the use of less expensive materials and processes. Perovskite solar cells provide a promising low-cost technology for harnessing this energy source. In Chapter two, a moisture-assist method is introduced and studied to facilitate grain growth of solution processed perovskite films. As an approach to achieve high-quality perovskite films, I anneal the precursor film in a humid environment (ambient air) to dramatically increase grain size, carrier mobility, and charge carrier lifetime, thus improving electrical and optical properties and enhancing photovoltaic performance. It is revealed that mild moisture has a positive effect on perovskite film formation, demonstrating perovskite solar cells with 17.1% power conversion efficiency. Later on, in Chapter four, an ultrathin flexible device delivering a PCE of 14.0% is introduced. The device is based on silver-mesh substrates exhibiting superior durability against mechanical bending. Due to their low energy of formation, organic lead iodide perovskites are also susceptible to degradation in moisture and air. The charge transport layer therefore plays a key role in protecting the perovskite photoactive layer from exposure to such environments, thus achieving highly stable perovskite-based photovoltaic cells. Although incorporating organic charge transport layers can provide high efficiencies and reduced hysteresis, concerns remain regarding device stability and the cost of fabrication. In this work, perovskite solar cells that have all solution-processed metal oxide charge transport layers were demonstrated. Stability has been significantly improved compared with cells made with organic layers. Degradation mechanisms were investigated and important guidelines were derived for future device design with a view to achieving both highly efficient and stable solar devices. Organometal halide based perovskite material has great optoelectronic proprieties, for example, shallow traps, benign grain boundaries and high diffusion length. The perovskite LEDs show pure electroluminescence (EL) with narrow full width at half maximum (FWHM), which is an advantage for display, lighting or lasing applications. In chapter five, perovskite LEDs are demonstrated employing solution processed charge injection layers with a quantum efficiency of 1.16% with a very low driving voltage.

Metal-halide perovskites for photovoltaic and light-emitting devices.

PubMed

Stranks, Samuel D; Snaith, Henry J

2015-05-01

Metal-halide perovskites are crystalline materials originally developed out of scientific curiosity. Unexpectedly, solar cells incorporating these perovskites are rapidly emerging as serious contenders to rival the leading photovoltaic technologies. Power conversion efficiencies have jumped from 3% to over 20% in just four years of academic research. Here, we review the rapid progress in perovskite solar cells, as well as their promising use in light-emitting devices. In particular, we describe the broad tunability and fabrication methods of these materials, the current understanding of the operation of state-of-the-art solar cells and we highlight the properties that have delivered light-emitting diodes and lasers. We discuss key thermal and operational stability challenges facing perovskites, and give an outlook of future research avenues that might bring perovskite technology to commercialization.

Prevention of breakdown behind railgun projectiles

DOEpatents

Hawke, R.S.

1992-10-13

An electromagnetic railgun accelerator system, for accelerating projectiles by a plasma arc, introduces a breakdown inhibiting gas into the railgun chamber behind the accelerating projectile. The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF[sub 6]. The gas is introduced between the railgun rails after the projectile has passed through inlets in the rails or the projectile; by coating the rails or the projectile with a material which releases the gas after the projectile passes over it; by fabricating the rails or the projectile or insulators out of a material which releases the gas into the portions of the chamber through which the projectile has travelled. The projectile may have a cavity at its rear to control the release of ablation products. 12 figs.

Prevention of breakdown behind railgun projectiles

DOEpatents

Hawke, R.S.

1992-09-01

An electromagnetic railgun accelerator system, for accelerating projectiles by a plasma arc, introduces a breakdown inhibiting gas into the railgun chamber behind the accelerating projectile. The breakdown inhibiting gas, which absorbs electrons, is a halide or a halide compound such as fluorine or SF[sub 6]. The gas is introduced between the railgun rails after the projectile has passed through inlets in the rails or the projectile; by coating the rails or the projectile with a material which releases the gas after the projectile passes over it; by fabricating the rails or the projectile or insulators out of a material which releases the gas into the portions of the chamber through which the projectile has travelled. The projectile may have a cavity at its rear to control the release of ablation products. 12 figs.

The Role of Metal Halide Perovskites in Next-Generation Lighting Devices.

PubMed

Lozano, Gabriel

2018-06-28

The development of smart illumination sources represents a central challenge of the current technology. In this context, the quest for novel materials that enable efficient light generation is essential. Metal halide compounds with perovskite crystalline structure (ABX3) have gained tremendous interest in the last five years since they come as easy-to-prepare high performance semiconductors. Perovskite absorbers are driving the power-conversion-efficiencies of thin film photovoltaics to unprecedented values. Nowadays, mixed-cation mixed-halide lead perovskite solar cells reach efficiencies consistently over 20% and promise to get close to 30% in multi-junction devices when combined with silicon cells at no surcharge. Nonetheless, perovskites' fame extends further since extensive research on these novel semiconductors has also revealed their brightest side. Soon after their irruption in the photovoltaic scenario, demonstration of efficient color tunable -with high color purity- perovskite emitters has opened new avenues for light generation applications that are timely to discuss herein.

Ultrasmooth organic-inorganic perovskite thin-film formation and crystallization for efficient planar heterojunction solar cells.

PubMed

Zhang, Wei; Saliba, Michael; Moore, David T; Pathak, Sandeep K; Hörantner, Maximilian T; Stergiopoulos, Thomas; Stranks, Samuel D; Eperon, Giles E; Alexander-Webber, Jack A; Abate, Antonio; Sadhanala, Aditya; Yao, Shuhua; Chen, Yulin; Friend, Richard H; Estroff, Lara A; Wiesner, Ulrich; Snaith, Henry J

2015-01-30

To date, there have been a plethora of reports on different means to fabricate organic-inorganic metal halide perovskite thin films; however, the inorganic starting materials have been limited to halide-based anions. Here we study the role of the anions in the perovskite solution and their influence upon perovskite crystal growth, film formation and device performance. We find that by using a non-halide lead source (lead acetate) instead of lead chloride or iodide, the perovskite crystal growth is much faster, which allows us to obtain ultrasmooth and almost pinhole-free perovskite films by a simple one-step solution coating with only a few minutes annealing. This synthesis leads to improved device performance in planar heterojunction architectures and answers a critical question as to the role of the anion and excess organic component during crystallization. Our work paves the way to tune the crystal growth kinetics by simple chemistry.

Spatially resolved multicolor CsPbX 3 nanowire heterojunctions via anion exchange

DOE PAGES

Dou, Letian; Lai, Minliang; Kley, Christopher S.; ...

2017-06-26

Halide perovskites are promising semiconductor materials for solution-processed optoelectronic devices. Their strong ionic bonding nature results in highly dynamic crystal lattices, inherently allowing rapid ion exchange at the solid–vapor and solid–liquid interface. In this paper, we show that the anion-exchange chemistry can be precisely controlled in single-crystalline halide perovskite nanomaterials when combined with nanofabrication techniques. We demonstrate spatially resolved multicolor CsPbX 3 (X = Cl, Br, I, or alloy of two halides) nanowire heterojunctions with a pixel size down to 500 nm with the photoluminescence tunable over the entire visible spectrum. In addition, the heterojunctions show distinct electronic states acrossmore » the interface, as revealed by Kelvin probe force microscopy. Finally, these perovskite heterojunctions represent key building blocks for high-resolution multicolor displays beyond current state-of-the-art technology as well as high-density diode/transistor arrays.« less

Partial oxidation process for producing a stream of hot purified gas

DOEpatents

Leininger, Thomas F.; Robin, Allen M.; Wolfenbarger, James K.; Suggitt, Robert M.

1995-01-01

A partial oxidation process for the production of a stream of hot clean gas substantially free from particulate matter, ammonia, alkali metal compounds, halides and sulfur-containing gas for use as synthesis gas, reducing gas, or fuel gas. A hydrocarbonaceous fuel comprising a solid carbonaceous fuel with or without liquid hydrocarbonaceous fuel or gaseous hydrocarbon fuel, wherein said hydrocarbonaceous fuel contains halides, alkali metal compounds, sulfur, nitrogen and inorganic ash containing components, is reacted in a gasifier by partial oxidation to produce a hot raw gas stream comprising H.sub.2, CO, CO.sub.2, H.sub.2 O, CH.sub.4, NH.sub.3, HCl, HF, H.sub.2 S, COS, N.sub.2, Ar, particulate matter, vapor phase alkali metal compounds, and molten slag. The hot raw gas stream from the gasifier is split into two streams which are separately deslagged, cleaned and recombined. Ammonia in the gas mixture is catalytically disproportionated into N.sub.2 and H.sub.2. The ammonia-free gas stream is then cooled and halides in the gas stream are reacted with a supplementary alkali metal compound to remove HCl and HF. Alkali metal halides, vaporized alkali metal compounds and residual fine particulate matter are removed from the gas stream by further cooling and filtering. The sulfur-containing gases in the process gas stream are then reacted at high temperature with a regenerable sulfur-reactive mixed metal oxide sulfur sorbent material to produce a sulfided sorbent material which is then separated from the hot clean purified gas stream having a temperature of at least 1000.degree. F.

Partial oxidation process for producing a stream of hot purified gas

DOEpatents

Leininger, T.F.; Robin, A.M.; Wolfenbarger, J.K.; Suggitt, R.M.

1995-03-28

A partial oxidation process is described for the production of a stream of hot clean gas substantially free from particulate matter, ammonia, alkali metal compounds, halides and sulfur-containing gas for use as synthesis gas, reducing gas, or fuel gas. A hydrocarbonaceous fuel comprising a solid carbonaceous fuel with or without liquid hydrocarbonaceous fuel or gaseous hydrocarbon fuel, wherein said hydrocarbonaceous fuel contains halides, alkali metal compounds, sulfur, nitrogen and inorganic ash containing components, is reacted in a gasifier by partial oxidation to produce a hot raw gas stream comprising H{sub 2}, CO, CO{sub 2}, H{sub 2}O, CH{sub 4}, NH{sub 3}, HCl, HF, H{sub 2}S, COS, N{sub 2}, Ar, particulate matter, vapor phase alkali metal compounds, and molten slag. The hot raw gas stream from the gasifier is split into two streams which are separately deslagged, cleaned and recombined. Ammonia in the gas mixture is catalytically disproportionated into N{sub 2} and H{sub 2}. The ammonia-free gas stream is then cooled and halides in the gas stream are reacted with a supplementary alkali metal compound to remove HCl and HF. Alkali metal halides, vaporized alkali metal compounds and residual fine particulate matter are removed from the gas stream by further cooling and filtering. The sulfur-containing gases in the process gas stream are then reacted at high temperature with a regenerable sulfur-reactive mixed metal oxide sulfur sorbent material to produce a sulfided sorbent material which is then separated from the hot clean purified gas stream having a temperature of at least 1000 F. 1 figure.

Tailoring the Ag + Content within the Tunnels and on the Exposed Surfaces of α-MnO 2 Nanowires: Impact on Impedance and Electrochemistry

DOE PAGES

Zhang, Bingjie; Smith, Paul F.; Lee, Seung-Yong; ...

2016-12-01

Efficient conduction of both electrons and cations (e.g., Li +) has a profound effect on the current and capacity of lithium-based batteries. With this study, we focus on cathode effects, with the preparation of pure silver hollandite materials with variable silver ion content within (intra-tunnel) and on the surface of α-MnO 2 tunneled materials, followed by the measurement and analysis of impedance and electrochemistry data. Specifically, pure Ag xMn 8O 16-y materials with low (x = 1.13) and high (x = 1.54) intra-tunnel silver content are compared with Ag xMn 8O 16-y·aAg 2O (a = 0.25, 0.63, 1.43) composites preparedmore » via a new Ag 2O coating strategy. When the Ag 2O (a = 0, 0.25) content is low, the material with higher intra-tunnel silver (x = 1.53) content delivers up to ~5-fold higher capacity accounted for by a ~10-fold lower impedance than its lower intra-tunnel silver (x = 1.13) counterpart. In the presence of high Ag 2O content (a = 0.63, 1.43), both composites exhibit comparable impedance but the lower intra-tunnel silver (x = 1.13) composite delivers up to ~1.5-fold higher capacity than higher intra-tunnel silver composite, highlighting the key role of Li + transport under those conditions. Our results demonstrate material design strategies which can significantly increase electronic and ionic conductivities.« less

Food safety concerns deriving from the use of silver based food packaging materials.

PubMed

Pezzuto, Alessandra; Losasso, Carmen; Mancin, Marzia; Gallocchio, Federica; Piovesana, Alessia; Binato, Giovanni; Gallina, Albino; Marangon, Alberto; Mioni, Renzo; Favretti, Michela; Ricci, Antonia

2015-01-01

The formulation of innovative packaging solutions, exerting a functional antimicrobial role in slowing down food spoilage, is expected to have a significant impact on the food industry, allowing both the maintenance of food safety criteria for longer periods and the reduction of food waste. Different materials are considered able to exert the required antimicrobial activity, among which are materials containing silver. However, challenges exist in the application of silver to food contact materials due to knowledge gaps in the production of ingredients, stability of delivery systems in food matrices and health risks caused by the same properties which also offer the benefits. Aims of the present study were to test the effectiveness and suitability of two packaging systems, one of which contained silver, for packaging and storing Stracchino cheese, a typical Italian fresh cheese, and to investigate if there was any potential for consumers to be exposed to silver, via migration from the packaging to the cheese. Results did not show any significant difference in the effectiveness of the packaging systems on packaged Stracchino cheese, excluding that the active packaging systems exerted an inhibitory effect on the growth of spoilage microorganisms. Moreover, silver migrated into the cheese matrix throughout the storage time (24 days). Silver levels in cheese finally exceeded the maximum established level for the migration of a non-authorised substance through a functional barrier (Commission of the European Communities, 2009). This result poses safety concerns and strongly suggests the need for more research aimed at better characterizing the new packaging materials in terms of their potential impacts on human health and the environment.

Tailoring the Ag + Content within the Tunnels and on the Exposed Surfaces of α-MnO 2 Nanowires: Impact on Impedance and Electrochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Bingjie; Smith, Paul F.; Lee, Seung-Yong

Efficient conduction of both electrons and cations (e.g., Li +) has a profound effect on the current and capacity of lithium-based batteries. With this study, we focus on cathode effects, with the preparation of pure silver hollandite materials with variable silver ion content within (intra-tunnel) and on the surface of α-MnO 2 tunneled materials, followed by the measurement and analysis of impedance and electrochemistry data. Specifically, pure Ag xMn 8O 16-y materials with low (x = 1.13) and high (x = 1.54) intra-tunnel silver content are compared with Ag xMn 8O 16-y·aAg 2O (a = 0.25, 0.63, 1.43) composites preparedmore » via a new Ag 2O coating strategy. When the Ag 2O (a = 0, 0.25) content is low, the material with higher intra-tunnel silver (x = 1.53) content delivers up to ~5-fold higher capacity accounted for by a ~10-fold lower impedance than its lower intra-tunnel silver (x = 1.13) counterpart. In the presence of high Ag 2O content (a = 0.63, 1.43), both composites exhibit comparable impedance but the lower intra-tunnel silver (x = 1.13) composite delivers up to ~1.5-fold higher capacity than higher intra-tunnel silver composite, highlighting the key role of Li + transport under those conditions. Our results demonstrate material design strategies which can significantly increase electronic and ionic conductivities.« less

Maximizing and stabilizing luminescence from halide perovskites with potassium passivation

NASA Astrophysics Data System (ADS)

Abdi-Jalebi, Mojtaba; Andaji-Garmaroudi, Zahra; Cacovich, Stefania; Stavrakas, Camille; Philippe, Bertrand; Richter, Johannes M.; Alsari, Mejd; Booker, Edward P.; Hutter, Eline M.; Pearson, Andrew J.; Lilliu, Samuele; Savenije, Tom J.; Rensmo, Håkan; Divitini, Giorgio; Ducati, Caterina; Friend, Richard H.; Stranks, Samuel D.

2018-03-01

Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions. Furthermore, in mixed halide perovskite systems designed for continuous bandgap tunability (bandgaps of approximately 1.7 to 1.9 electronvolts), photoinduced ion segregation leads to bandgap instabilities. Here we demonstrate substantial mitigation of both non-radiative losses and photoinduced ion migration in perovskite films and interfaces by decorating the surfaces and grain boundaries with passivating potassium halide layers. We demonstrate external photoluminescence quantum yields of 66 per cent, which translate to internal yields that exceed 95 per cent. The high luminescence yields are achieved while maintaining high mobilities of more than 40 square centimetres per volt per second, providing the elusive combination of both high luminescence and excellent charge transport. When interfaced with electrodes in a solar cell device stack, the external luminescence yield—a quantity that must be maximized to obtain high efficiency—remains as high as 15 per cent, indicating very clean interfaces. We also demonstrate the inhibition of transient photoinduced ion-migration processes across a wide range of mixed halide perovskite bandgaps in materials that exhibit bandgap instabilities when unpassivated. We validate these results in fully operating solar cells. Our work represents an important advance in the construction of tunable metal halide perovskite films and interfaces that can approach the efficiency limits in tandem solar cells, coloured-light-emitting diodes and other optoelectronic applications.

Maximizing and stabilizing luminescence from halide perovskites with potassium passivation.

PubMed

Abdi-Jalebi, Mojtaba; Andaji-Garmaroudi, Zahra; Cacovich, Stefania; Stavrakas, Camille; Philippe, Bertrand; Richter, Johannes M; Alsari, Mejd; Booker, Edward P; Hutter, Eline M; Pearson, Andrew J; Lilliu, Samuele; Savenije, Tom J; Rensmo, Håkan; Divitini, Giorgio; Ducati, Caterina; Friend, Richard H; Stranks, Samuel D

2018-03-21

Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions. Furthermore, in mixed halide perovskite systems designed for continuous bandgap tunability (bandgaps of approximately 1.7 to 1.9 electronvolts), photoinduced ion segregation leads to bandgap instabilities. Here we demonstrate substantial mitigation of both non-radiative losses and photoinduced ion migration in perovskite films and interfaces by decorating the surfaces and grain boundaries with passivating potassium halide layers. We demonstrate external photoluminescence quantum yields of 66 per cent, which translate to internal yields that exceed 95 per cent. The high luminescence yields are achieved while maintaining high mobilities of more than 40 square centimetres per volt per second, providing the elusive combination of both high luminescence and excellent charge transport. When interfaced with electrodes in a solar cell device stack, the external luminescence yield-a quantity that must be maximized to obtain high efficiency-remains as high as 15 per cent, indicating very clean interfaces. We also demonstrate the inhibition of transient photoinduced ion-migration processes across a wide range of mixed halide perovskite bandgaps in materials that exhibit bandgap instabilities when unpassivated. We validate these results in fully operating solar cells. Our work represents an important advance in the construction of tunable metal halide perovskite films and interfaces that can approach the efficiency limits in tandem solar cells, coloured-light-emitting diodes and other optoelectronic applications.

Comparison of DNA Damage and Apoptosis Induced By Silver Nanoparticle-containing Dressing Materials During Wound Healing.

PubMed

Choi, Young Suk; Gwak, Heui-Chul; Park, Jae Keun; Lim, Ji Yun; Yeo, Eui Dong; Park, Eunseok; Kim, Junyong; Lee, Young Koo

2018-04-13

Silver nanoparticle (AgNP)-containing dressings are used worldwide for the treatment of wounds; however, many studies have indicated that AgNPs are toxic to humans and cause cell death, primarily via apoptosis. In this study, the investigators compare the apoptotic effects of various AgNP dressing materials, with the hypothesis that nanosilver would be less toxic than ionic silver. For the in vivo experiments, Sprague-Dawley (SD) and streptozotocin (STZ)-induced diabetic rats were treated with 5 dressing materials: Aquacel Ag (product A, silver ion; ConvaTec, Berkshire, UK), Acticoat (product B, AgNP; Smith & Nephew, Fort Worth, TX), Medifoam Silver (product C, silver ion; Genewel Science Co Ltd, Seongnam, South Korea), PolyMem Silver (product D, AgNP; Ferris Mfg Corp, Fort Worth, TX), and Vaseline-impregnated dressing gauze (control; Unilever, London, UK). All treatments were applied 3 times per week. After 14 days of treatment, the SD and STZ rats were euthanized, and wound samples were examined for apoptosis. The analysis included immunohistochemistry, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Western blotting, and reverse transcription polymerase chain reaction for a semiquantitative evaluation of apoptosis. The AgNP-containing dressing materials were more cytotoxic than the silver dressings. Compared with the AgNP dressing materials, no significant levels of apoptotic factors were observed in the silver dressing-treated wounds. The TUNEL staining showed that product C-dressed wounds contained the most apoptotic cells, while some apoptotic cells were observed in product B-dressed wounds. Moreover, apoptotic gene expression was altered, including a decline in B-cell lymphoma-2 and activation of caspase-3. This was most evident in wounds treated with product C. Interestingly, apoptotic gene expression was not induced in product A-treated wounds. Finally, product D had a relatively lower silver concentration and was less toxic than products A-C. Dressing materials containing AgNP have an antimicrobial effect. However, the authors observed that some AgNP dressings induced DNA damage and apoptosis. Although AgNP dressings did not cause significant acute apoptotic effects, they should be examined for cytotoxic effects in chronic wounds and should be used with caution when treating chronic wounds and those with low bacteria counts.

Size- and coating-dependent cytotoxicity and genotoxicity of silver nanoparticles evaluated using in vitro standard assays.

PubMed

Guo, Xiaoqing; Li, Yan; Yan, Jian; Ingle, Taylor; Jones, Margie Yvonne; Mei, Nan; Boudreau, Mary D; Cunningham, Candice K; Abbas, Mazhar; Paredes, Angel M; Zhou, Tong; Moore, Martha M; Howard, Paul C; Chen, Tao

2016-11-01

The physicochemical characteristics of silver nanoparticles (AgNPs) may greatly alter their toxicological potential. To explore the effects of size and coating on the cytotoxicity and genotoxicity of AgNPs, six different types of AgNPs, having three different sizes and two different coatings, were investigated using the Ames test, mouse lymphoma assay (MLA) and in vitro micronucleus assay. The genotoxicities of silver acetate and silver nitrate were evaluated to compare the genotoxicity of nanosilver to that of ionic silver. The Ames test produced inconclusive results for all types of the silver materials due to the high toxicity of silver to the test bacteria and the lack of entry of the nanoparticles into the cells. Treatment of L5718Y cells with AgNPs and ionic silver resulted in concentration-dependent cytotoxicity, mutagenicity in the Tk gene and the induction of micronuclei from exposure to nearly every type of the silver materials. Treatment of TK6 cells with these silver materials also resulted in concentration-dependent cytotoxicity and significantly increased micronucleus frequency. With both the MLA and micronucleus assays, the smaller the AgNPs, the greater the cytotoxicity and genotoxicity. The coatings had less effect on the relative genotoxicity of AgNPs than the particle size. Loss of heterozygosity analysis of the induced Tk mutants indicated that the types of mutations induced by AgNPs were different from those of ionic silver. These results suggest that AgNPs induce cytotoxicity and genotoxicity in a size- and coating-dependent manner. Furthermore, while the MLA and in vitro micronucleus assay (in both types of cells) are useful to quantitatively measure the genotoxic potencies of AgNPs, the Ames test cannot.

Composition-Graded Cesium Lead Halide Perovskite Nanowires with Tunable Dual-Color Lasing Performance.

PubMed

Huang, Ling; Gao, Qinggang; Sun, Ling-Dong; Dong, Hao; Shi, Shuo; Cai, Tong; Liao, Qing; Yan, Chun-Hua

2018-05-21

Cesium lead halide (CsPbX 3 ) perovskite has emerged as a promising low-threshold multicolor laser material; however, realizing wavelength-tunable lasing output from a single CsPbX 3 nanostructure is still constrained by integrating different composition. Here, the direct synthesis of composition-graded CsPbBr x I 3- x nanowires (NWs) is reported through vapor-phase epitaxial growth on mica. The graded composition along the NW, with an increased Br/I from the center to the ends, comes from desynchronized deposition of cesium lead halides and temperature-controlled anion-exchange reaction. The graded composition results in varied bandgaps along the NW, which induce a blueshifted emission from the center to the ends. As an efficient gain media, the nanowire exerts position-dependent lasing performance, with a different color at the ends and center respectively above the threshold. Meanwhile, dual-color lasing with a wavelength separation of 35 nm is activated simultaneously at a site with an intermediate composition. This position-dependent dual-color lasing from a single nanowire makes these metal halide perovskites promising for applications in nanoscale optical devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nickel-silver composition shows promise as catalyst for hydrogen-oxygen fuel cells

NASA Technical Reports Server (NTRS)

Magerl, J. A.; Murray, J. N.

1970-01-01

Carburized 3-1 nickel-silver preparation exhibits considerable catalytic activity, although not as high as platinum black. Cost and availability factors warrant further evaluation of nickel-silver materials.

A multi-material coating containing chemically-modified apatites for combined enhanced bioactivity and reduced infection via a drop-on-demand micro-dispensing technique.

PubMed

Lim, Poon Nian; Wang, Zuyong; Chang, Lei; Konishi, Toshiisa; Choong, Cleo; Ho, Bow; Thian, Eng San

2017-01-01

Prevention of infection and enhanced osseointegration are closely related, and required for a successful orthopaedic implant, which necessitate implant designs to consider both criteria in tandem. A multi-material coating containing 1:1 ratio of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite as the top functional layer, and hydroxyapatite as the base layer, was produced via the drop-on-demand micro-dispensing technique, as a strategic approach in the fight against infection along with the promotion of bone tissue regeneration. The homogeneous distribution of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets at alternate position in silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating delayed the exponential growth of Staphylococcus aureus for up to 24 h, and gave rise to up-regulated expression of alkaline phosphatase activity, type I collagen and osteocalcin as compared to hydroxyapatite and silver-substituted hydroxyapatite coatings. Despite containing reduced amounts of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets over the coated area than silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite coatings, silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating exhibited effective antibacterial property with enhanced bioactivity. By exhibiting good controllability of distributing silicon-substituted hydroxyapatite, silver-substituted hydroxyapatite and hydroxyapatite micro-droplets, it was demonstrated that drop-on-demand micro-dispensing technique was capable in harnessing the advantages of silver-substituted hydroxyapatite, silicon-substituted hydroxyapatite and hydroxyapatite to produce a multi-material coating along with enhanced bioactivity and reduced infection.

Lithium-tellurium bimetallic cell has increased voltage

NASA Technical Reports Server (NTRS)

Cairns, E. J.; Rogers, G. L.; Shimotake, H.

1968-01-01

Lithium-tellurium secondary cell with a fused lithium halide electrolyte, tested in the temperature range 467 degrees to 500 degrees C, showed improvement over the sodium bismuth cell. The voltage of this bimetallic cell was increased by using the more electropositive anode material, lithium, and the more electronegative cathode material, tellurium.

Silver doped catalysts for treatment of exhaust

DOEpatents

Park, Paul Worn; Hester, Virgil Raymond; Ragle, Christie Susan; Boyer, Carrie L.

2009-06-02

A method of making an exhaust treatment element includes washcoating a substrate with a slurry that includes a catalyst support material. At least some of the catalyst support material from the slurry may be transferred to the substrate, and silver metal (Ag) is dispersed within the catalyst support material.

High-Throughput Fabrication Method for Producing a Silver-Nanoparticles-Doped Nanoclay Polymer Composite with Novel Synergistic Antibacterial Effects at the Material Interface.

PubMed

Cai, Shaobo; Pourdeyhimi, Behnam; Loboa, Elizabeth G

2017-06-28

In this study, we report a high-throughput fabrication method at industrial pilot scale to produce a silver-nanoparticles-doped nanoclay-polylactic acid composite with a novel synergistic antibacterial effect. The obtained nanocomposite has a significantly lower affinity for bacterial adhesion, allowing the loading amount of silver nanoparticles to be tremendously reduced while maintaining satisfactory antibacterial efficacy at the material interface. This is a great advantage for many antibacterial applications in which cost is a consideration. Furthermore, unlike previously reported methods that require additional chemical reduction processes to produce the silver-nanoparticles-doped nanoclay, an in situ preparation method was developed in which silver nanoparticles were created simultaneously during the composite fabrication process by thermal reduction. This is the first report to show that altered material surface submicron structures created with the loading of nanoclay enables the creation of a nanocomposite with significantly lower affinity for bacterial adhesion. This study provides a promising scalable approach to produce antibacterial polymeric products with minimal changes to industry standard equipment, fabrication processes, or raw material input cost.

Silver ion-mediated killing of a food pathogen: Melting curve analysis data of silver resistance genes and growth curve data.

PubMed

Gokulan, Kuppan; Williams, Katherine; Khare, Sangeeta

2017-04-01

Limited antibacterial activity of silver ions leached from silver-impregnated food contact materials could be due to: 1) the presence of silver resistance genes in tested bacteria ; or 2) lack of susceptibility to silver ion-mediated killing in the bacterial strain (K. Williams, L. Valencia, K. Gokulan, R. Trbojevich, S. Khare, 2016 [1]). This study contains data to address the specificity of silver resistance genes in Salmonella Typhimurium during the real time PCR using melting curve analysis and an assessment of the minimum inhibitory concentration of silver ions for Salmonella .

Method of preparing nitrogen containing semiconductor material

DOEpatents

Barber, Greg D.; Kurtz, Sarah R.

2004-09-07

A method of combining group III elements with group V elements that incorporates at least nitrogen from a nitrogen halide for use in semiconductors and in particular semiconductors in photovoltaic cells.

Cavitational synthesis of nanostructured inorganic materials for enhanced heterogeneous catalysis

NASA Astrophysics Data System (ADS)

Krausz, Ivo Michael

The synthesis of nanostructured inorganic materials by hydrodynamic cavitation processing was investigated. The goal of this work was to develop a general synthesis technique for nanostructured materials with a control over crystallite size in the 1--20 nm range. Materials with crystallite sizes in this range have shown enhanced catalytic activity compared to materials with larger crystallite sizes. Several supported and unsupported inorganic materials were studied to understand the effects of cavitation on crystallite size. Cavitation processing of calcium fluoride resulted in more spherical particles, attached to one another by melted necks. This work produced the first evidence of shock wave heating of nanostructured materials by hydrodynamic cavitation processing. Hydrodynamic cavitation synthesis of various catalytic support materials indicated that their phase composition and purity could be controlled by adjustment of the processing parameters. Zirconia/alumina supports synthesized using hydro-dynamic cavitation and calcined to 1368 K retained a high purity cubic zirconia phase, whereas classically prepared samples showed a phase transformation to monoclinic zirconia. Similarly, the synthesis of alumina resulted in materials with varying Bohmite and Bayerite contents as a function of the process parameters. High temperature calcination resulted in stable alumina supports with varying amounts of delta-, and theta-alumina. Synthesis studies of palladium and silver showed modest variations in crystallite size as a function of cavitation process parameters. Calcination resulted in larger grain materials, indicating a disappearance of intergrain boundaries. Based on these results, a new synthesis method was studied involving controlled agglomeration of small silver crystallites by hydrodynamic cavitation processing, followed by deposition on alumina. The optimal pH, concentration, and processing time for controlling the silver crystallite size in the cavitation equipment were determined using a statistical design of experiments approach. Three series of alumina supported silver catalysts were prepared, with silver weight loadings of 1%, 2%, and 5%. Variation of cavitation processing time between 1--64 min allowed the systematic control of silver crystallite size in the range of 3--19 nm. The preferred oxidation of CO in hydrogen (PROX) was chosen as a catalytic test reaction, because of its increasing importance for fuel cell applications. It was found that the catalytic activity was significantly increased for silver crystallite sizes below 5 nm. This work is the first experimental evidence of independent crystallite size control by hydrodynamic cavitation for alumina supported silver catalysts. The synthesis method involving controlled agglomeration and calcination is a general synthesis procedure that can be used to synthesize a wide range of novel catalysts and advanced materials.

The production of antibacterial tubing, sutures, and bandages by in situ precipitation of metallic salts.

PubMed

Farrah, S R; Erdos, G W

1991-06-01

Two procedures were used to modify gauze bandages, polyester sutures, silicone tubing, and polyvinyl chloride tubing. In one procedure, the materials were first modified by in situ precipitation of metallic hydroxides and then used to adsorb silver ions. In the second procedure, the materials were soaked in sodium pyrophosphate or sodium chloride, dried, and then soaked in silver nitrate. These procedures produced materials with silver deposited on the surface of the tubing and sutures and both on the surface and within the gauze fibers. The modified materials inhibited the growth of Pseudomonas aeruginosa. Escherichia coli, and Staphylococcus aureus in vitro.

Low-Temperature Properties of Silver

PubMed Central

Smith, David R.; Fickett, F. R.

1995-01-01

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability. PMID:29151733

How Important Is the Organic Part of Lead Halide Perovskite Photovoltaic Cells? Efficient CsPbBr3 Cells.

PubMed

Kulbak, Michael; Cahen, David; Hodes, Gary

2015-07-02

Hybrid organic-inorganic lead halide perovskite photovoltaic cells have already surpassed 20% conversion efficiency in the few years that they have been seriously studied. However, many fundamental questions still remain unanswered as to why they are so good. One of these is "Is the organic cation really necessary to obtain high quality cells?" In this study, we show that an all-inorganic version of the lead bromide perovskite material works equally well as the organic one, in particular generating the high open circuit voltages that are an important feature of these cells.

The reaction of Grignard reagents with Bunte salts: a thiol-free synthesis of sulfides.

PubMed

Reeves, Jonathan T; Camara, Kaddy; Han, Zhengxu S; Xu, Yibo; Lee, Heewon; Busacca, Carl A; Senanayake, Chris H

2014-02-21

S-Alkyl, S-aryl, and S-vinyl thiosulfate sodium salts (Bunte salts) react with Grignard reagents to give sulfides in good yields. The S-alkyl Bunte salts are prepared from odorless sodium thiosulfate by an SN2 reaction with alkyl halides. A Cu-catalyzed coupling of sodium thiosulfate with aryl and vinyl halides was developed to access S-aryl and S-vinyl Bunte salts. The reaction is amenable to a broad structural array of Bunte salts and Grignard reagents. Importantly, this route to sulfides avoids the use of malodorous thiol starting materials or byproducts.

Genesis, challenges and opportunities for colloidal lead halide perovskite nanocrystals

NASA Astrophysics Data System (ADS)

Akkerman, Quinten A.; Rainò, Gabriele; Kovalenko, Maksym V.; Manna, Liberato

2018-05-01

Lead halide perovskites (LHPs) in the form of nanometre-sized colloidal crystals, or nanocrystals (NCs), have attracted the attention of diverse materials scientists due to their unique optical versatility, high photoluminescence quantum yields and facile synthesis. LHP NCs have a `soft' and predominantly ionic lattice, and their optical and electronic properties are highly tolerant to structural defects and surface states. Therefore, they cannot be approached with the same experimental mindset and theoretical framework as conventional semiconductor NCs. In this Review, we discuss LHP NCs historical and current research pursuits, challenges in applications, and the related present and future mitigation strategies explored.

Transformation of sintered CsPbBr 3 nanocrystals to cubic CsPbI 3 and gradient CsPbBr xI 3–x through halide exchange

DOE PAGES

Hoffman, Jacob B.; Schleper, A. Lennart; Kamat, Prashant V.

2016-06-20

All-inorganic cesium lead halide (CsPbX 3, X = Br –, I –) perovskites could potentially provide comparable photovoltaic performance with enhanced stability compared to organic–inorganic lead halide species. However, small-bandgap cubic CsPbI3 has been difficult to study due to challenges forming CsPbI 3 in the cubic phase. Here, a low-temperature procedure to form cubic CsPbI 3 has been developed through a halide exchange reaction using films of sintered CsPbBr 3 nanocrystals. The reaction was found to be strongly dependent upon temperature, featuring an Arrhenius relationship. Additionally, film thickness played a significant role in determining internal film structure at intermediate reactionmore » times. Thin films (50 nm) showed only a small distribution of CsPbBr xI 3–x species, while thicker films (350 nm) exhibited much broader distributions. Furthermore, internal film structure was ordered, featuring a compositional gradient within film. Transient absorption spectroscopy showed the influence of halide exchange on the excited state of the material. In thicker films, charge carriers were rapidly transferred to iodide-rich regions near the film surface within the first several picoseconds after excitation. Furthermore, this ultrafast vectorial charge-transfer process illustrates the potential of utilizing compositional gradients to direct charge flow in perovskite-based photovoltaics.« less

Effect of halide-mixing on the switching behaviors of organic-inorganic hybrid perovskite memory

NASA Astrophysics Data System (ADS)

Hwang, Bohee; Gu, Chungwan; Lee, Donghwa; Lee, Jang-Sik

2017-03-01

Mixed halide perovskite materials are actively researched for solar cells with high efficiency. Their hysteresis which originates from the movement of defects make perovskite a candidate for resistive switching memory devices. We demonstrate the resistive switching device based on mixed-halide organic-inorganic hybrid perovskite CH3NH3PbI3-xBrx (x = 0, 1, 2, 3). Solvent engineering is used to deposit the homogeneous CH3NH3PbI3-xBrx layer on the indium-tin oxide-coated glass substrates. The memory device based on CH3NH3PbI3-xBrx exhibits write endurance and long retention, which indicate reproducible and reliable memory properties. According to the increase in Br contents in CH3NH3PbI3-xBrx the set electric field required to make the device from low resistance state to high resistance state decreases. This result is in accord with the theoretical calculation of migration barriers, that is the barrier to ionic migration in perovskites is found to be lower for Br- (0.23 eV) than for I- (0.29-0.30 eV). The resistive switching may be the result of halide vacancy defects and formation of conductive filaments under electric field in the mixed perovskite layer. It is observed that enhancement in operating voltage can be achieved by controlling the halide contents in the film.

Antibacterial properties and mechanisms of gold-silver nanocages

NASA Astrophysics Data System (ADS)

Wang, Yulan; Wan, Jiangshan; Miron, Richard J.; Zhao, Yanbin; Zhang, Yufeng

2016-05-01

Despite the number of antibiotics used in routine clinical practice, bacterial infections continue to be one of the most important challenges faced in humans. The main concerns arise from the continuing emergence of antibiotic-resistant bacteria and the difficulties faced with the pharmaceutical development of new antibiotics. Thus, advancements in the avenue of novel antibacterial agents are essential. In this study, gold (Au) was combined with silver (Ag), a well-known antibacterial material, to form silver nanoparticles producing a gold-silver alloy structure with hollow interiors and porous walls (gold-silver nanocage). This novel material was promising in antibacterial applications due to its better biocompatibility than Ag nanoparticles, potential in photothermal effects and drug delivery ability. The gold-silver nanocage was then tested for its antibacterial properties and the mechanism involved leading to its antibacterial properties. This study confirms that this novel gold-silver nanocage has broad-spectrum antibacterial properties exerting its effects through the destruction of the cell membrane, production of reactive oxygen species (ROS) and induction of cell apoptosis. Therefore, we introduce a novel gold-silver nanocage that serves as a potential nanocarrier for the future delivery of antibiotics.

Reducing Environmental Toxicity of Silver Nanoparticles through Shape Control.

PubMed

Gorka, Danielle E; Osterberg, Joshua S; Gwin, Carley A; Colman, Benjamin P; Meyer, Joel N; Bernhardt, Emily S; Gunsch, Claudia K; DiGulio, Richard T; Liu, Jie

2015-08-18

The use of antibacterial silver nanomaterials in consumer products ranging from textiles to toys has given rise to concerns over their environmental toxicity. These materials, primarily nanoparticles, have been shown to be toxic to a wide range of organisms; thus methods and materials that reduce their environmental toxicity while retaining their useful antibacterial properties can potentially solve this problem. Here we demonstrate that silver nanocubes display a lower toxicity toward the model plant species Lolium multiflorum while showing similar toxicity toward other environmentally relevant and model organisms (Danio rerio and Caenorhabditis elegans) and bacterial species (Esherichia coli, Bacillus cereus, and Pseudomonas aeruginosa) compared to quasi-spherical silver nanoparticles and silver nanowires. More specifically, in the L. multiflorum experiments, the roots of silver nanocube treated plants were 5.3% shorter than the control, while silver nanoparticle treated plant roots were 39.6% shorter than the control. The findings here could assist in the future development of new antibacterial products that cause less environmental toxicity after their intended use.

New complexes of silver (I) with N-hydroxy-succinimide

NASA Astrophysics Data System (ADS)

Sibiescu, Doina; Mîţǎ, Carmen; Vizitiu, Mihaela; Crudu, Andra Manuela

2016-12-01

Over the last period of time silver was considerably studied due to its lower resistivity. In the field of materials science, silver was used in applications such as: microelectronics components of high - temperature superconductiviting materials, bactericidal coatings and others domains. This study presents the process of obtaining and characterization the new complexes of silver (I) with Nhydroxy- succinimide. In the process of obtaining the new complex compounds in aqous solution, first we have to look at conductometry and UV-Vis absorbtion spectroscopy in order to determine the molar ratio silver : N-hydroxysuccinimide and the stability constants. The obtained solid coordination compounds were characterized by elemental analysis, IR spectroscopy and also was investigated of their thermostability. The X-ray powder diffraction reflects that the complexes compounds of silver (I) with N-hydroxysuccinimide are amorphous. In our further studies we want to determine if the new synthetized compounds will present the same or improuved properties as in the above mentioned silver characteristics.

Colloidal Nanocrystals of Lead-Free Double-Perovskite (Elpasolite) Semiconductors: Synthesis and Anion Exchange To Access New Materials.

PubMed

Creutz, Sidney E; Crites, Evan N; De Siena, Michael C; Gamelin, Daniel R

2018-02-14

Concerns about the toxicity and instability of lead-halide perovskites have driven a recent surge in research toward alternative lead-free perovskite materials, including lead-free double perovskites with the elpasolite structure and visible bandgaps. Synthetic approaches to this class of materials remain limited, however, and no examples of heterometallic elpasolites as nanomaterials have been reported. Here, we report the synthesis and characterization of colloidal nanocrystals of Cs 2 AgBiX 6 (X = Cl, Br) elpasolites using a hot-injection approach. We further show that postsynthetic modification through anion exchange and cation extraction can be used to convert these nanocrystals to new materials including Cs 2 AgBiI 6 , which was previously unknown experimentally. Nanocrystals of Cs 2 AgBiI 6 , synthesized via a novel anion-exchange protocol using trimethylsilyl iodide, have strong absorption throughout the visible region, confirming theoretical predictions that this material could be a promising photovoltaic absorber. The synthetic methodologies presented here are expected to be broadly generalizable. This work demonstrates that nanocrystal ion-exchange reactivity can be used to discover and develop new lead-free halide perovskite materials that may be difficult or impossible to access through direct synthesis.

Polymerization initated at sidewalls of carbon nanotubes

NASA Technical Reports Server (NTRS)

Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)

2011-01-01

The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

Novel antibacterial mouthguard material manufactured using silver-nanoparticleembedded ethylene-vinyl acetate copolymer masterbatch.

PubMed

Yoshida, Yuriko; Churei, Hiroshi; Takeuchi, Yasuo; Wada, Takahiro; Uo, Motohiro; Izumi, Yuichi; Ueno, Toshiaki

2018-01-26

The purpose of the present study was to develop an antibacterial mouthguard (MG) material using a masterbatch of silvernanoparticle-embedded ethylene-vinyl acetate (EVA) copolymers. In order to verify that the testing material was clinically applicable as an antibacterial MG material, we conducted an antibacterial test, a shock absorption test, and analysis of in vitro silver release. The colony-forming activity of Streptococcus sobrinus, Porphyromonas gingivalis, and Escherichia coli were significantly inhibited on the testing materials compared with the commercial EVA sheet (p<0.05). The shock absorption capability of the testing material was not significantly different from that of the commercial EVA sheet. Cumulative silver release (in pure water) from the testing materials were infinitesimal after soaking for 20 days, which implied that there could be no harm in wearing the MG during exercise. These results showed that this testing material could be clinically applicable as an antibacterial MG material.

Comparative activity of silver based antimicrobial composites for urinary catheters.

PubMed

Thokala, Nikhil; Kealey, Carmel; Kennedy, James; Brady, Damien B; Farrell, Joseph

2018-04-04

Biomedical polymers are an integral component in a wide range of medical device designs due to their range of desirable properties. However, extensive use of polymer materials in medical devices have also been associated with an increasing incidence of patient infections. Efforts to address this issue have included the incorporation of antimicrobial additives for developing novel antimicrobial polymeric materials. Silver with its high toxicity towards bacteria, oligodynamic effect and good thermal stability has been employed as an additive for polymeric medical devices. In the present study, commercially available elemental (Biogate) and ionic (Ultrafresh 16) silver additives were incorporated into a Polyamide 11 (PA 11) matrix using a compression press. These polymer composites were evaluated for their antimicrobial and ion release properties. Elemental silver composites were determined to retain their antimicrobial properties for extended periods and actively release silver ions for 84 days; whereas the ionic silver composites lost their ion release activity and therefore antibacterial activity after 56 days. Bacterial log reduction units of 3.87 for ionic silver and 2.41 for elemental silver was identified within 24 hr, when tested in accordance with ISO 22196 test standard; indicating that ionic silver is more efficient for short-term applications compared to elemental silver. Copyright © 2018 Elsevier Ltd. All rights reserved.

Characterisation and potential migration of silver nanoparticles from commercially available polymeric food contact materials.

PubMed

Addo Ntim, Susana; Thomas, Treye A; Begley, Timothy H; Noonan, Gregory O

2015-01-01

The potential for consumer exposure to nano-components in food contact materials (FCMs) is dependent on the migration of nanomaterials into food. Therefore, characterising the physico-chemical properties and potential for migration of constituents is an important step in assessing the safety of FCMs. A number of commercially available food storage products, purchased domestically within the United States and internationally, that claim to contain nanosilver were evaluated. The products were made of polyethylene, polypropylene and polyphenylene ether sulfone and all contained silver (0.001-36 mg kg(-1) of polymer). Silver migration was measured under various conditions, including using 3% acetic acid and water as food simulants. Low concentrations (sub-ppb levels) of silver were detected in the migration studies generally following a trend characterised by a surface desorption phenomenon, where the majority of the silver migration occurred in the first of three consecutive exposures. Silver nanoparticles were not detected in food simulants, suggesting that the silver migration may be due solely to ionic silver released into solution from oxidation of the silver nanoparticle surface. The absence of detectable silver nanoparticles was consistent with expectations from a physico-chemical view point. For the products tested, current USFDA guidance for evaluating migration from FCMs was applicable.

A perspective on the hemolytic activity of chemical and green-synthesized silver and silver oxide nanoparticles

NASA Astrophysics Data System (ADS)

Ashokraja, C.; Sakar, M.; Balakumar, S.

2017-10-01

We report the hemolysis properties of silver and silver oxide nanoparticles (NPs) prepared by chemical and green-synthesis methods. The prepared silver and silver oxide NPs were analyzed using UV-vis spectroscopy to confirm their formation by characterizing their surface plasmon resonance (SPR) and absorption band peaks respectively. The Fourier transmission infrared (FTIR) spectra of the materials showed the characteristic functional groups corresponding to the molecules present in leaf extracts, which is proposed to be acted as reducing and capping agents that are also found on the surface of silver and silver oxide nanoparticles that synthesized via green-synthesis method. Zeta potential analysis revealed the surface charge and stability of the prepared NPs. HRTEM images showed almost spherical shape nanoparticles with an average size of 15.2 and 31.5 nm for wet chemical synthesized silver and silver oxide nanoparticles respectively. In the case of green synthesized silver and silver oxide nanoparticles, it was observed to be 19.4 and 30.4 nm respectively. The order of hemolysis efficacy of the materials is found to be as follows: chemically synthesized Ag2O>  chemically synthesized Ag NPs followed by green-synthesized Ag2O and green-synthesized Ag NPs which showed almost similar hemolysis with respect to concentration. The relatively stable nature of the silver NPs could be attributed to their lower hemolysis efficacy, while the increased lysis properties of silver oxide could be attributed due to reductive/oxidative processes that give rise to the hemolysis through interfacial charge interactions with RBCs.

Printed silver nanowire antennas with low signal loss at high-frequency radio

NASA Astrophysics Data System (ADS)

Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

2012-05-01

Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film.Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film. Electronic supplementary information (ESI) available: Operation of R/C car with a silver nanowire monopole antenna. See DOI: 10.1039/c2nr30485f

Rate Dependency of Silver Vanadium Phosphorous Oxide Reduction

NASA Astrophysics Data System (ADS)

Cheng, Po-Jen

2011-12-01

The silver vanadium phosphorus oxide (Ag2VO2PO 4) is a high-capacity and good-compatibility material for the cathode in the battery. Due to their innovative properties, they are used as cathode in lithium batteries. Therefore, when the lithium batteries begin to discharge, the anodes of the cell perform an electrochemical oxidation and release electrons. In the mean time, the cathodes in the cells perform the electrochemical reduction and catch the electrons. For reduction of Ag2VO2PO 4, two silver ions (Ag+) catch two electrons to form silver particles, and the vanadium ions (V5+) catch two electrons to form V3+. It means that four electrons will be released by lithium anode. We call this four electrons discharge as 100% discharge. In my most of the projects, the Ag2VO2PO4 material is tested by differential scanning calorimetry (DSC) to check purity. My study is based on the discharge of batteries, and I focus on the morphology and the intensity of silver particles on the cathode after discharge. Depending on different adjustment of factors, such as discharge time, discharge rate, storage time, storage temperature, I try to investigate the silver intensity, conductivity as a function of DOD (Depth of Discharge). The silver particles could be examined by optical microscope, and scanning electron microscope (SEM). Moreover, I do some x-ray diffraction analysis to quantify the silver particles after discharge. Also, I perform magnetic susceptibility measurement to check the mechanism of the reduction of vanadium ions. Under the research on silver ions and vanadium ions, I will know a big frame of reduction process on silver vanadium phosphorous oxide and the time effect on this cathode material.

Chemistry Notes.

ERIC Educational Resources Information Center

School Science Review, 1983

1983-01-01

Presents background information, laboratory procedures, classroom materials/activities, and chemistry experiments. Topics include sublimation, electronegativity, electrolysis, experimental aspects of strontianite, halide test, evaluation of present and future computer programs in chemistry, formula building, care of glass/saturated calomel…

Going Beyond, Going Further: Knives, Forks, and Beer Cans as Potentiometric Sensors.

ERIC Educational Resources Information Center

Selig, Walter S.

1985-01-01

Background information, materials needed, and procedures used are provided for potentiometric fluoride, halide, orthophosphate, and sulfate titrations. Typical results obtained are also provided for each type of titration. (JN)

Application of modern autoradiography to nuclear forensic analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parsons-Davis, Tashi; Knight, Kim; Fitzgerald, Marc

Modern autoradiography techniques based on phosphorimaging technology using image plates (IPs) and digital scanning can identify heterogeneities in activity distributions and reveal material properties, serving to inform subsequent analyses. Here, we have adopted these advantages for applications in nuclear forensics, the technical analysis of radioactive or nuclear materials found outside of legal control to provide data related to provenance, production history, and trafficking route for the materials. IP autoradiography is a relatively simple, non-destructive method for sample characterization that records an image reflecting the relative intensity of alpha and beta emissions from a two-dimensional surface. Such data are complementary tomore » information gathered from radiochemical characterization via bulk counting techniques, and can guide the application of other spatially resolved techniques such as scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). IP autoradiography can image large 2-dimenstional areas (up to 20 × 40 cm), with relatively low detection limits for actinides and other radioactive nuclides, and sensitivity to a wide dynamic range (10 5) of activity density in a single image. Distributions of radioactivity in nuclear materials can be generated with a spatial resolution of approximately 50 μm using IP autoradiography and digital scanning. While the finest grain silver halide films still provide the best possible resolution (down to ~10 μm), IP autoradiography has distinct practical advantages such as shorter exposure times, no chemical post-processing, reusability, rapid plate scanning, and automated image digitization. Sample preparation requirements are minimal, and the analytical method does not consume or alter the sample. These advantages make IP autoradiography ideal for routine screening of nuclear materials, and for the identification of areas of interest for subsequent micro-characterization methods. Here in this article we present a summary of our setup, as modified for nuclear forensic sample analysis and related research, and provide examples of data from select samples from the nuclear fuel cycle and historical nuclear test debris.« less

Application of modern autoradiography to nuclear forensic analysis

DOE PAGES

Parsons-Davis, Tashi; Knight, Kim; Fitzgerald, Marc; ...

2018-05-20

Modern autoradiography techniques based on phosphorimaging technology using image plates (IPs) and digital scanning can identify heterogeneities in activity distributions and reveal material properties, serving to inform subsequent analyses. Here, we have adopted these advantages for applications in nuclear forensics, the technical analysis of radioactive or nuclear materials found outside of legal control to provide data related to provenance, production history, and trafficking route for the materials. IP autoradiography is a relatively simple, non-destructive method for sample characterization that records an image reflecting the relative intensity of alpha and beta emissions from a two-dimensional surface. Such data are complementary tomore » information gathered from radiochemical characterization via bulk counting techniques, and can guide the application of other spatially resolved techniques such as scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). IP autoradiography can image large 2-dimenstional areas (up to 20 × 40 cm), with relatively low detection limits for actinides and other radioactive nuclides, and sensitivity to a wide dynamic range (10 5) of activity density in a single image. Distributions of radioactivity in nuclear materials can be generated with a spatial resolution of approximately 50 μm using IP autoradiography and digital scanning. While the finest grain silver halide films still provide the best possible resolution (down to ~10 μm), IP autoradiography has distinct practical advantages such as shorter exposure times, no chemical post-processing, reusability, rapid plate scanning, and automated image digitization. Sample preparation requirements are minimal, and the analytical method does not consume or alter the sample. These advantages make IP autoradiography ideal for routine screening of nuclear materials, and for the identification of areas of interest for subsequent micro-characterization methods. Here in this article we present a summary of our setup, as modified for nuclear forensic sample analysis and related research, and provide examples of data from select samples from the nuclear fuel cycle and historical nuclear test debris.« less

Application of modern autoradiography to nuclear forensic analysis.

PubMed

Parsons-Davis, Tashi; Knight, Kim; Fitzgerald, Marc; Stone, Gary; Caldeira, Lee; Ramon, Christina; Kristo, Michael

2018-05-01

Modern autoradiography techniques based on phosphorimaging technology using image plates (IPs) and digital scanning can identify heterogeneities in activity distributions and reveal material properties, serving to inform subsequent analyses. Here, we have adopted these advantages for applications in nuclear forensics, the technical analysis of radioactive or nuclear materials found outside of legal control to provide data related to provenance, production history, and trafficking route for the materials. IP autoradiography is a relatively simple, non-destructive method for sample characterization that records an image reflecting the relative intensity of alpha and beta emissions from a two-dimensional surface. Such data are complementary to information gathered from radiochemical characterization via bulk counting techniques, and can guide the application of other spatially resolved techniques such as scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). IP autoradiography can image large 2-dimenstional areas (up to 20×40cm), with relatively low detection limits for actinides and other radioactive nuclides, and sensitivity to a wide dynamic range (10 5 ) of activity density in a single image. Distributions of radioactivity in nuclear materials can be generated with a spatial resolution of approximately 50μm using IP autoradiography and digital scanning. While the finest grain silver halide films still provide the best possible resolution (down to ∼10μm), IP autoradiography has distinct practical advantages such as shorter exposure times, no chemical post-processing, reusability, rapid plate scanning, and automated image digitization. Sample preparation requirements are minimal, and the analytical method does not consume or alter the sample. These advantages make IP autoradiography ideal for routine screening of nuclear materials, and for the identification of areas of interest for subsequent micro-characterization methods. In this paper we present a summary of our setup, as modified for nuclear forensic sample analysis and related research, and provide examples of data from select samples from the nuclear fuel cycle and historical nuclear test debris. Copyright © 2018 Elsevier B.V. All rights reserved.

Amorphous and nanocrystalline luminescent Si and Ge obtained via a solid-state chemical metathesis synthesis route

NASA Astrophysics Data System (ADS)

McMillan, Paul F.; Gryko, Jan; Bull, Craig; Arledge, Richard; Kenyon, Anthony J.; Cressey, Barbara A.

2005-03-01

A new solid-state metathesis synthesis route was applied to obtain bulk samples of amorphous or microcrystalline Si and Ge. The method involves reaction of Zintl phases such as NaSi or NaGe, with ammonium or metal (e.g., CuCl, CoBr 2) halides. The driving force for the solid-state reaction is provided by the formation of alkali halides and the transition metals or metal silicides, or gaseous ammonia and hydrogen. The semiconductors were purified by washing to remove other solid products. The amorphous semiconductors were obtained in bulk form from reactions carried out at 200-300 °C. Syntheses at higher temperatures gave rise to microcrystalline semiconductors, or to micro-/nanocrystalline particles contained within the amorphous material. Similar crystalline/amorphous composites were obtained after heat treatment of bulk amorphous materials.

Fabrication of Planar Heterojunction Perovskite Solar Cells by Controlled Low-Pressure Vapor Annealing.

PubMed

Li, Yanbo; Cooper, Jason K; Buonsanti, Raffaella; Giannini, Cinzia; Liu, Yi; Toma, Francesca M; Sharp, Ian D

2015-02-05

A new method for achieving high efficiency planar CH3NH3I3-xClx perovskite photovoltaics, based on a low pressure, reduced temperature vapor annealing is demonstrated. Heterojunction devices based on this hybrid halide perovskite exhibit a top PCE of 16.8%, reduced J-V hysteresis, and highly repeatable performance without need for a mesoporous or nanocrystalline metal oxide layer. Our findings demonstrate that large hysteresis is not an inherent feature of planar heterojunctions, and that efficient charge extraction can be achieved with uniform halide perovskite materials with desired composition. X-ray diffraction, valence band spectroscopy, and transient absorption measurements of these thin films reveal that structural modifications induced by chlorine clearly dominate over chemical and electronic doping effects, without affecting the Fermi level or photocarrier lifetime in the material.

New Scintillator Materials (K2CeBr5) and (Cs2CeBr5)

NASA Technical Reports Server (NTRS)

Hawrami, R.; Volz, M. P.; Batra, A. K.; Aggarwal, M. D.; Roy, U. N.; Groza, M.; Burger, A.; Cherepy, Nerine; Niedermayr, Thomas; Payne, Stephen A.

2008-01-01

Cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5) are new scintillator materials for X-ray and gamma ray detector applications. Recently halide scintillator materials, such as Ce doped lanthanum bromide has been proved to be very important material for the same purpose. These materials are highly hygroscopic; a search for high light yield non-hygroscopic materials was highly desirable to advance the scintillator technology. In this paper, we are reporting the crystal growth of novel scintillator materials, cesium cerium bromide (Cs2CeBr5) and potassium cerium bromide (K2CeBr5). Crystals were successfully grown from the melt using the vertical Bridgman-Stockbarger technique, in a comparison with the high performance LaBr3 or LaCl3 crystals, cerium based alkali halides crystals, (Cs2CeBr5) and (K2CeBr5) have similar scintillation properties, while being much less hygroscopic. Furthermore, cesium based compounds will not suffer from the self-activity present in potassium and lanthanum compounds. However the Cs2CeBr5 crystals did not grow properly probably due to non-congruent melting or to some phase transition during cooling. Keywords." Scintillator materials; Ce3+; Energy resolution; Light yield; K2CeBr5

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

DOE PAGES

Hoye, Robert L. Z.; Schulz, Philip; Schelhas, Laura T.; ...

2017-02-28

Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculatingmore » the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials and how these challenges may be overcome. The topic was discussed at a seminar at the 2015 Materials Research Society Fall Meeting & Exhibit. This article highlights the lessons learned from the seminar and the insights of some of the attendees, with reference to both recent literature and controlled experiments to illustrate the challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy, and calculations on perovskites and new, related absorbers. We suggest how the reporting of the important artifacts could be streamlined between groups to ensure reproducibility as the field progresses.« less

Perovskite-Inspired Photovoltaic Materials: Toward Best Practices in Materials Characterization and Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoye, Robert L. Z.; Schulz, Philip; Schelhas, Laura T.

Recently, there has been an explosive growth in research based on hybrid lead-halide perovskites for photovoltaics owing to rapid improvements in efficiency. The advent of these materials for solar applications has led to widespread interest in understanding the key enabling properties of these materials. This has resulted in renewed interest in related compounds and a search for materials that may replicate the defect-tolerant properties and long lifetimes of the hybrid lead-halide perovskites. Given the rapid pace of development of the field, the rises in efficiencies of these systems have outpaced the more basic understanding of these materials. Measuring or calculatingmore » the basic properties, such as crystal/electronic structure and composition, can be challenging because some of these materials have anisotropic structures, and/or are composed of both heavy metal cations and volatile, mobile, light elements. Some consequences are beam damage during characterization, composition change under vacuum, or compound effects, such as the alteration of the electronic structure through the influence of the substrate. These effects make it challenging to understand the basic properties integral to optoelectronic operation. Compounding these difficulties is the rapid pace with which the field progresses. This has created an ongoing need to continually evaluate best practices with respect to characterization and calculations, as well as to identify inconsistencies in reported values to determine if those inconsistencies are rooted in characterization methodology or materials synthesis. This article describes the difficulties in characterizing hybrid lead-halide perovskites and new materials and how these challenges may be overcome. The topic was discussed at a seminar at the 2015 Materials Research Society Fall Meeting & Exhibit. This article highlights the lessons learned from the seminar and the insights of some of the attendees, with reference to both recent literature and controlled experiments to illustrate the challenges discussed. The focus in this article is on crystallography, composition measurements, photoemission spectroscopy, and calculations on perovskites and new, related absorbers. We suggest how the reporting of the important artifacts could be streamlined between groups to ensure reproducibility as the field progresses.« less

Solution growth of single crystal methylammonium lead halide perovskite nanostructures for optoelectronic and photovoltaic applications.

PubMed

Fu, Yongping; Meng, Fei; Rowley, Matthew B; Thompson, Blaise J; Shearer, Melinda J; Ma, Dewei; Hamers, Robert J; Wright, John C; Jin, Song

2015-05-06

Understanding crystal growth and improving material quality is important for improving semiconductors for electronic, optoelectronic, and photovoltaic applications. Amidst the surging interest in solar cells based on hybrid organic-inorganic lead halide perovskites and the exciting progress in device performance, improved understanding and better control of the crystal growth of these perovskites could further boost their optoelectronic and photovoltaic performance. Here, we report new insights on the crystal growth of the perovskite materials, especially crystalline nanostructures. Specifically, single crystal nanowires, nanorods, and nanoplates of methylammonium lead halide perovskites (CH3NH3PbI3 and CH3NH3PbBr3) are successfully grown via a dissolution-recrystallization pathway in a solution synthesis from lead iodide (or lead acetate) films coated on substrates. These single crystal nanostructures display strong room-temperature photoluminescence and long carrier lifetime. We also report that a solid-liquid interfacial conversion reaction can create a highly crystalline, nanostructured MAPbI3 film with micrometer grain size and high surface coverage that enables photovoltaic devices with a power conversion efficiency of 10.6%. These results suggest that single-crystal perovskite nanostructures provide improved photophysical properties that are important for fundamental studies and future applications in nanoscale optoelectronic and photonic devices.

Principles of Chemical Bonding and Band Gap Engineering in Hybrid Organic-Inorganic Halide Perovskites.

PubMed

Walsh, Aron

2015-03-19

The performance of solar cells based on hybrid halide perovskites has seen an unparalleled rate of progress, while our understanding of the underlying physical chemistry of these materials trails behind. Superficially, CH 3 NH 3 PbI 3 is similar to other thin-film photovoltaic materials: a semiconductor with an optical band gap in the optimal region of the electromagnetic spectrum. Microscopically, the material is more unconventional. Progress in our understanding of the local and long-range chemical bonding of hybrid perovskites is discussed here, drawing from a series of computational studies involving electronic structure, molecular dynamics, and Monte Carlo simulation techniques. The orientational freedom of the dipolar methylammonium ion gives rise to temperature-dependent dielectric screening and the possibility for the formation of polar (ferroelectric) domains. The ability to independently substitute on the A, B, and X lattice sites provides the means to tune the optoelectronic properties. Finally, ten critical challenges and opportunities for physical chemists are highlighted.

Research progress on organic-inorganic halide perovskite materials and solar cells

NASA Astrophysics Data System (ADS)

Ono, Luis K.; Qi, Yabing

2018-03-01

Owing to the intensive research efforts across the world since 2009, perovskite solar cell power conversion efficiencies (PCEs) are now comparable or even better than several other photovoltaic (PV) technologies. In this topical review article, we review recent progress in the field of organic-inorganic halide perovskite materials and solar cells. We associate these achievements with the fundamental knowledge gained in the perovskite research. The major recent advances in the fundamental perovskite material and solar cell research are highlighted, including the current efforts in visualizing the dynamical processes (in operando) taking place within a perovskite solar cell under operating conditions. We also discuss the existing technological challenges. Based on a survey of recently published works, we point out that to move the perovskite PV technology forward towards the next step of commercialization, what perovskite PV technology need the most in the coming next few years is not only further PCE enhancements, but also up-scaling, stability, and lead-toxicity.

Study of defects in TlBr, InI as potential semiconductor radiation detectors

NASA Astrophysics Data System (ADS)

Biswas, Koushik; Du, Mao-Hua

2011-03-01

Group III-halides such as TlBr and InI are receiving considerable attention for application in room temperature radiation detector devices. It is however, essential that these detector materials have favorable defect properties which enable good carrier transport when operating under an external bias voltage. We have studied the properties of native defects of InI and Tlbr and several important results emerge: (1) Schottky defects are the dominant low-energy defects in both materials that can potentially pin the Fermi level close to midgap, leading to high resistivity; (2) native defects in TlBr are benign in terms of electron trapping. However, anion-vacancy in InI induces a deep electron trap similar to the F -centers in alkali halides. This can reduce electron mobility-lifetime product in InI; (3) low diffusion barriers of vacancies and ionic conductivity could be responsible for the observed polarization phenomenon in both materials at room temperature. U.S. DOE Office of Nonproliferation Research and Development NA22.

Direct X-ray detection with hybrid solar cells based on organolead halide perovskites

NASA Astrophysics Data System (ADS)

Gill, Hardeep Singh; Elshahat, Bassem; Sajo, Erno; Kumar, Jayant; Kokil, Akshay; Zygmanski, Piotr; Li, Lian; Mosurkal, Ravi

2014-03-01

Organolead halide perovskite materials are attracting considerable interest due to their exceptional opto-electronic properties, such as, high charge carrier mobilities, high exciton diffusion length, high extinction coefficients and broad-band absorption. These interesting properties have enabled their application in high performance hybrid photovoltaic devices. The high Z value of their constituents also makes these materials efficient for absorbing X-rays. Here we will present on the efficient use of hybrid solar cells based on organolead perovskite materials as X-ray detectors. Hybrid solar cells based on CH3NH3PbI3 were fabricated using facile processing techniques on patterned indium tin oxide coated glass substrates. The solar cells typically had a planar configuration of ITO/CH3NH3PbI3/P3HT/Ag. High sensitivity for X-rays due to high Z value, larger carrier mobility and better charge collection was observed. Detecting X-rays with energies relevant to medical oncology applications opens up the potential for diagnostic imaging applications.

Perovskite–fullerene hybrid materials suppress hysteresis in planar diodes

PubMed Central

Xu, Jixian; Buin, Andrei; Ip, Alexander H.; Li, Wei; Voznyy, Oleksandr; Comin, Riccardo; Yuan, Mingjian; Jeon, Seokmin; Ning, Zhijun; McDowell, Jeffrey J.; Kanjanaboos, Pongsakorn; Sun, Jon-Paul; Lan, Xinzheng; Quan, Li Na; Kim, Dong Ha; Hill, Ian G.; Maksymovych, Peter; Sargent, Edward H.

2015-01-01

Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite–PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3− antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solar cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour. PMID:25953105

Principles of Chemical Bonding and Band Gap Engineering in Hybrid Organic–Inorganic Halide Perovskites

PubMed Central

2015-01-01

The performance of solar cells based on hybrid halide perovskites has seen an unparalleled rate of progress, while our understanding of the underlying physical chemistry of these materials trails behind. Superficially, CH3NH3PbI3 is similar to other thin-film photovoltaic materials: a semiconductor with an optical band gap in the optimal region of the electromagnetic spectrum. Microscopically, the material is more unconventional. Progress in our understanding of the local and long-range chemical bonding of hybrid perovskites is discussed here, drawing from a series of computational studies involving electronic structure, molecular dynamics, and Monte Carlo simulation techniques. The orientational freedom of the dipolar methylammonium ion gives rise to temperature-dependent dielectric screening and the possibility for the formation of polar (ferroelectric) domains. The ability to independently substitute on the A, B, and X lattice sites provides the means to tune the optoelectronic properties. Finally, ten critical challenges and opportunities for physical chemists are highlighted. PMID:25838846

Perovskite-Fullerene Hybrid Materials Eliminate Hysteresis In Planar Diodes

DOE PAGES

Xu, Jixian; Buin, Andrei; Ip, Alexander H.; ...

2015-03-31

Solution-processed planar perovskite devices are highly desirable in a wide variety of optoelectronic applications; however, they are prone to hysteresis and current instabilities. Here we report the first perovskite–PCBM hybrid solid with significantly reduced hysteresis and recombination loss achieved in a single step. This new material displays an efficient electrically coupled microstructure: PCBM is homogeneously distributed throughout the film at perovskite grain boundaries. The PCBM passivates the key PbI3 antisite defects during the perovskite self-assembly, as revealed by theory and experiment. Photoluminescence transient spectroscopy proves that the PCBM phase promotes electron extraction. We showcase this mixed material in planar solarmore » cells that feature low hysteresis and enhanced photovoltage. Using conductive AFM studies, we reveal the memristive properties of perovskite films. We close by positing that PCBM, by tying up both halide-rich antisites and unincorporated halides, reduces electric field-induced anion migration that may give rise to hysteresis and unstable diode behaviour.« less

In vitro caries-inhibitory properties of a silver cermet.

PubMed

Swift, E J

1989-06-01

Recurrent caries is one of the primary causes of failure of dental restorations. One method for reducing the frequency and severity of this problem is the use of fluoride-releasing restorative materials. The glass-ionomer cements are a type of fluoride-releasing material. They have been used extensively in recent years for a variety of clinical applications. However, in comparison with other restorative materials such as amalgam and composite resins, glass ionomers have relatively poor physical properties. Sintering of silver particles to glass-ionomer powder is a means of improving these physical properties. The sintered material is called a silver-glass ionomer or silver cermet. This study examined the in vitro caries-inhibitory potential of a silver cement by means of two methods. First, long-term fluoride release was measured. Second, an artificial caries system was used for evaluation of caries inhibition by cerment restorations in extracted teeth. In comparison with a standard glass-ionomer restorative material, fluoride release from the cermet material was significantly less throughout a 12-month period. The results from the artificial caries system indicated that this decreased fluoride release corresponded with a lesser degree of caries inhibition. Lesions around cermet restorations in both enamel and root surfaces were significantly more severe than those around conventional glass-ionomer restorations. However, in comparison with amalgam and composite resin restorations, the cermet did have some cariostatic activity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, Riley E.; Poindexter, Jeremy R.; Gorai, Prashun

Recently, we and others have proposed screening criteria for 'defect-tolerant' photovoltaic (PV) absorbers, identifying several classes of semiconducting compounds with electronic structures similar to those of hybrid lead-halide perovskites. In this work, we reflect on the accuracy and prospects of these new design criteria through a combined experimental and theoretical approach. We construct a model to extract photoluminescence lifetimes of six of these candidate PV absorbers, including four (InI, SbSI, SbSeI, and BiOI) for which time-resolved photoluminescence has not been previously reported. The lifetimes of all six candidate materials exceed 1 ns, a threshold for promising early stage PV devicemore » performance. However, there are variations between these materials, and none achieve lifetimes as high as those of the hybrid lead-halide perovskites, suggesting that the heuristics for defect-tolerant semiconductors are incomplete. Here, we explore this through first-principles point defect calculations and Shockley-Read-Hall recombination models to describe the variation between the measured materials. In light of these insights, we discuss the evolution of screening criteria for defect tolerance and high-performance PV materials.« less

Metal-Halide Perovskite Transistors for Printed Electronics: Challenges and Opportunities.

PubMed

Lin, Yen-Hung; Pattanasattayavong, Pichaya; Anthopoulos, Thomas D

2017-12-01

Following the unprecedented rise in photovoltaic power conversion efficiencies during the past five years, metal-halide perovskites (MHPs) have emerged as a new and highly promising class of solar-energy materials. Their extraordinary electrical and optical properties combined with the abundance of the raw materials, the simplicity of synthetic routes, and processing versatility make MHPs ideal for cost-efficient, large-volume manufacturing of a plethora of optoelectronic devices that span far beyond photovoltaics. Herein looks beyond current applications in the field of energy, to the area of large-area electronics using MHPs as the semiconductor material. A comprehensive overview of the relevant fundamental material properties of MHPs, including crystal structure, electronic states, and charge transport, is provided first. Thereafter, recent demonstrations of MHP-based thin-film transistors and their application in logic circuits, as well as bi-functional devices such as light-sensing and light-emitting transistors, are discussed. Finally, the challenges and opportunities in the area of MHPs-based electronics, with particular emphasis on manufacturing, stability, and health and environmental concerns, are highlighted. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ionic-Electronic Ambipolar Transport in Metal Halide Perovskites: Can Electronic Conductivity Limit Ionic Diffusion?

PubMed

Kerner, Ross A; Rand, Barry P

2018-01-04

Ambipolar transport describes the nonequilibrium, coupled motion of positively and negatively charged particles to ensure that internal electric fields remain small. It is commonly invoked in the semiconductor community where the motion of excess electrons and holes drift and diffuse together. However, the concept of ambipolar transport is not limited to semiconductor physics. Materials scientists working on ion conducting ceramics understand ambipolar transport dictates the coupled diffusion of ions and the rate is limited by the ion with the lowest diffusion coefficient. In this Perspective, we review a third application of ambipolar transport relevant to mixed ionic-electronic conducting materials for which the motion of ions is expected to be coupled to electronic carriers. In this unique situation, the ambipolar diffusion model has been successful at explaining the photoenhanced diffusion of metal ions in chalcogenide glasses and other properties of materials. Recent examples of photoenhanced phenomena in metal halide perovskites are discussed and indicate that mixed ionic-electronic ambipolar transport is similarly important for a deep understanding of these emerging materials.

Shift Happens. How Halide Ion Defects Influence Photoinduced Segregation in Mixed Halide Perovskites

DOE PAGES

Yoon, Seog Joon; Kuno, Masaru; Kamat, Prashant V.

2017-06-01

Minimizing photoinduced segregation in mixed halide lead perovskites is important for achieving stable photovoltaic performance. The shift in the absorption and the rate of formation of iodide- and bromide-rich regions following visible excitation of mixed halide lead perovskites is found to strongly depend on the halide ion concentration. Slower formation and recovery rates observed in halide-deficient films indicate the involvement of defect sites in influencing halide phase segregation. At higher halide concentrations (in stoichiometric excess), segregation effects become less prominent, as evidenced by faster recovery kinetics. These results suggest that light-induced compositional segregation can be minimized in mixed halide perovskitemore » films by using excess halide ions. In conclusion, the findings from this study further reflect the importance of halide ion post-treatment of perovskite films to improve their solar cell performance.« less

Charcoal as a capture material for silver nanoparticles in the aquatic environment

NASA Astrophysics Data System (ADS)

McGillicuddy, Eoin; Morrison, Liam; Cormican, Martin; Morris, Dearbháile

2017-04-01

Background: The reported antibacterial activity of silver nanoparticles (AgNPs) has led to their incorporation into numerous consumer products including; textiles, domestic appliances, food containers, cosmetics, paints, medical and medicinal products. The AgNPs incorporated into these products can be released into the environment and aquatic system during their production, use and end of life disposal. In the aquatic environment, uncertainties surround the concentration, fate and effects of AgNPs. The aim of this project is to examine charcoal as a potential material for capture of silver nanoparticles from the aquatic environment. Material/methods: Activated charcoal is a commonly used filter material and was selected for this project to determine its suitability as a capture material for AgNPs in water samples. Activated charcoal (Norit® CA1 (Sigma-Aldrich)) was exposed to 100 ppb, 25 nm PVP coated AgNPs (nanoComposix) prepared in Milli-Q water. These solutions were exposed to unaltered charcoal granules for 20 hours after which the decrease of silver in the solution was measured using ICP-MS. In order to improve the removal, the surface area of the charcoal was increased firstly by grinding with a pestle and mortar and secondly by milling the charcoal. The milled charcoal was prepared using an agate ball mill running at 500 rpm for 5 minutes. The activated charcoal was then exposed to samples containing 10 ppb AgNPs. Results: In the initial tests, approximately 10% of the silver was removed from the water samples using the unaltered activated charcoal granules. Further experiments were carried out to compare the unaltered granules with the ground and milled charcoal. These tests were carried out similarly to the previous test however lower concentration of 10 ppb was used. After 20 hours of exposure the granule samples, as previously, showed approximately a 10% reduction in silver content with the ground charcoal giving approximately 30% reduction in silver concentration and in the sample exposed to milled charcoal, approximately 60% reduction in silver concentration was observed. These tests found that increasing the surface area of the charcoal increased the silver reduction in the solution. Conclusions: Data suggest that charcoal may be a suitable material for use in the capture of AgNPs from water samples

Inorganic separator technology program

NASA Technical Reports Server (NTRS)

Smatko, J. S.; Weaver, R. D.; Kalhammer, F. R.

1973-01-01

Testing and failure analyses of silver zinc cells with largely inorganic separators were performed. The results showed that the wet stand and cycle life objective of the silver-zinc cell development program were essentially accomplished and led to recommendations for cell composition, design, and operation that should yield further improvement in wet and cycle life. A series of advanced inorganic materials was successfully developed and formulated into rigid and semiflexible separator samples. Suitable screening tests for evaluation of largely inorganic separators were selected and modified for application to the separator materials. The results showed that many of these formulations are potentially superior to previously used materials and permitted selection of three promising materials for further evaluation in silver-zinc cells.

Gas-Phase Combustion Synthesis of Nonoxide Nanoparticles in Microgravity

NASA Technical Reports Server (NTRS)

Axelbaum, R. L.; Kumfer, B. M.; Sun, Z.; Chao, B. H.

2001-01-01

Gas-phase combustion synthesis is a promising process for creating nanoparticles for the growing nanostructure materials industry. The challenges that must be addressed are controlling particle size, preventing hard agglomerates, maintaining purity, and, if nonoxides are synthesized, protecting the particles from oxidation and/or hydrolysis during post-processing. Sodium-halide Flame Encapsulation (SFE) is a unique methodology for producing nonoxide nanoparticles that addresses these challenges. This flame synthesis process incorporates sodium and metal-halide chemistry, resulting in nanoparticles that are encapsulated in salt during the early stages of their growth in the flame. Salt encapsulation has been shown to allow control of particle size and morphology, while serving as an effective protective coating for preserving the purity of the core particles. Metals and compounds that have been produced using this technology include Al, W, Ti, TiB2, AlN, and composites of W-Ti and Al-AlN. Oxygen content in SFE synthesized nano- AlN has been measured by neutron activation analysis to be as low as 0.54wt.%, as compared to over 5wt.% for unprotected AlN of comparable size. The overall objective of this work is to study the SFE process and nano-encapsulation so that they can be used to produce novel and superior materials. SFE experiments in microgravity allow the study of flame and particle dynamics without the influence of buoyancy forces. Spherical sodium-halide flames are produced in microgravity by ejecting the halide from a spherical porous burner into a quiescent atmosphere of sodium vapor and argon. Experiments are performed in the 2.2 sec Drop Tower at the NASA-Glenn Research Center. Numerical models of the flame and particle dynamics were developed and are compared with the experimental results.

Dilution-Induced Formation of Hybrid Perovskite Nanoplatelets.

PubMed

Tong, Yu; Ehrat, Florian; Vanderlinden, Willem; Cardenas-Daw, Carlos; Stolarczyk, Jacek K; Polavarapu, Lakshminarayana; Urban, Alexander S

2016-12-27

Perovskite nanocrystals (NCs) are an important extension to the fascinating field of hybrid halide perovskites. Showing significantly enhanced photoluminescence (PL) efficiency and emission wavelengths tunable through halide content and size, they hold great promise for light-emitting applications. Despite the rapid advancement in this field, the physical nature and size-dependent excitonic properties have not been well investigated due to the challenges associated with their preparation. Herein we report the spontaneous formation of highly luminescent, quasi-2D organic-inorganic hybrid perovskite nanoplatelets (NPls) upon dilution of a dispersion of bulk-like NCs. The fragmentation of the large NCs is attributed to osmotic swelling induced by the added solvent. An excess of organic ligands in the solvent quickly passivates the newly formed surfaces, stabilizing the NPls in the process. The thickness of the NPls can be controlled both by the dilution level and by the ligand concentration. Such colloidal NPls and their thin films were found to be extremely stable under continuous UV light irradiation. Full tunability of the NPl emission wavelength is achieved by varying the halide ion used (bromide, iodide). Additionally, time-resolved PL measurements reveal an increasing radiative decay rate with decreasing thickness of the NPls, likely due to an increasing exciton binding energy. Similarly, measurements on iodide-containing NPls show a transformation from biexponential to monoexponential PL decay with decreasing thickness, likely due to an increasing fraction of excitonic recombination. This interesting phenomenon of change in fluorescence upon dilution is a result of the intricate nature of the perovskite material itself and is uncommon in inorganic materials. Our findings enable the synthesis of halide perovskite NCs with high quantum efficiency and good stability as well as a tuning of both their optical and morphological properties.

New Capabilities With Dry Silver Recording Materials

NASA Astrophysics Data System (ADS)

Morgan, David A.

1987-04-01

Dry Silver technology was discovered at 3M and introduced into various imaging applications in the mid-sixties. In the early 1980's, quality films and papers with extended spectral responses, greater dynamic ranges, and improved sensitivity and edge acuity were introduced into sophisticated imaging systems. These products also have improved shelf life at elevated storage temperatures, and improved print stability. At the present time, 3M is developing a full-color dry silver product. This product has the same rapid-access, easy-to-use characteristics as the black and white dry silver recording materials. It has high resolution, long gray scale, and adequate sensitivity for CRT's and other electronically addressable exposure devices. The product can be processed in the same processors used for the black and white dry silver products.

Characterization and antibacterial properties of porous fibers containing silver ions

NASA Astrophysics Data System (ADS)

Sun, Zhaoyang; Fan, Chenxu; Tang, Xiaopeng; Zhao, Jianghui; Song, Yanhua; Shao, Zhongbiao; Xu, Lan

2016-11-01

Materials prepared on the base of bioactive silver compounds have become more and more popular. In the present work, the surface morphology, structure and properties, of electrospun Polylactide Polylactic acid (PLA) porous fibers containing various ratios of silver ions were investigated by a combination of X-ray photoelectron spectroscopy (XPS), universal testing machine, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and et al. The biological activities of the proposed porous fibers were discussed in view of the released silver ions concentration. Antibacterial properties of these porous fibers were studied using two bacterial strains: Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). Results of the antibacterial testing suggested that PLA porous fibers containing silver ions could be used as potent antibacterial wound dressing materials in the biomedical field.

Self-Trapped Excitons in Ionic-Covalent Silver Halide Crystals and Nanostructures: High-Frequency EPR, ESE, ENDOR and ODMR Studies

PubMed Central

Baranov, P. G.; Poluektov, O. G.; Schmidt, J.

2010-01-01

Silver halides have unique features in solid state physics because their properties are considered to be of borderline nature between ionic and covalent bonding. In AgCl, the self-trapped hole (STH) is centered and partly trapped in the cationic sublattice, forming an Ag2+ ion inside of a (AgCl6)4− complex as a result of the Jahn–Teller distortion. The STH in AgCl can capture an electron from the conduction band forming the self-trapped exciton (STE). Recent results of a study of STE by means of high-frequency electron paramagnetic resonance, electron spin echo, electron–nuclear double resonance (ENDOR) and optically detected magnetic resonance (ODMR) are reviewed. The properties of the STE in AgCl crystals, such as exchange coupling, the ordering of the triplet and singlet sublevels, the dynamical properties of the singlet and triplet states, and the hyperfine interaction with the Ag and Cl (Br) nuclei are discussed. Direct information about the spatial distribution of the wave function of STE unpaired electrons was obtained by ENDOR. From a comparison with the results of an ENDOR study of the shallow electron center and STH, it is concluded that the electron is mainly contained in a hydrogen-like 1s orbital with a Bohr radius of 15.1 ± 0.6 Å, but near its center the electron density reflects the charge distribution of the hole. The hole of the STE is virtually identical to an isolated STH center. For AgCl nanocrystals embedded into the KCl crystalline matrix, the anisotropy of the g-factor of STE and STH was found to be substantially reduced compared with that of bulk AgCl crystals, which can be explained by a considerable suppression of the Jahn–Teller effect in nanoparticles. A study of ODMR in AgBr nanocrystals in KBr revealed spatial confinement effects and allowed estimating the nanocrystal size from the shape of the ODMR spectra. PMID:21151483

Clinical behaviour of glass ionomer restorations in primary teeth.

PubMed

Espelid, I; Tveit, A B; Tornes, K H; Alvheim, H

1999-08-01

To compare a silver-reinforced glass ionomer material (cermet) with a resin-modified glass ionomer in minimal Class II preparations in primary teeth. Matched pairs of primary molars with approximal caries that required operative treatment were used. Each cavity was filled with either Vitremer or Ketac-Silver. The restorations were followed for at least 36 months and examined annually using bitewing radiographs and clinical inspections. Impressions were taken at each recall and models were examined microscopically. After 36 months, one of the resin-modified glass ionomer (RMGI) restorations and 13 (26.5%) of the silver cermet restorations had failed. The RMGI failed because of secondary caries, while most of the failures of the silver cermet fillings were marginal defects alone or in combination with secondary caries. The median survival time (MST) for the silver cermet restorations was 37 months. The RMGI restorations had a MST exceeding 42 months, but MST could not be calculated exactly because of the low failure rate during the study period. The resin-modified glass ionomer had the overall best performance of the two materials under comparison. The silver cermet material cannot be recommended for Class II restorations in primary teeth.

120 years of nanosilver history: implications for policy makers.

PubMed

Nowack, Bernd; Krug, Harald F; Height, Murray

2011-02-15

Nanosilver is one nanomaterial that is currently under a lot of scrutiny. Much of the discussion is based on the assumption that nanosilver is something new that has not been seen until recently and that the advances in nanotechnology opened completely new application areas for silver. However, we show in this analysis that nanosilver in the form of colloidal silver has been used for more than 100 years and has been registered as a biocidal material in the United States since 1954. Fifty-three percent of the EPA-registered biocidal silver products likely contain nanosilver. Most of these nanosilver applications are silver-impregnated water filters, algicides, and antimicrobial additives that do not claim to contain nanoparticles. Many human health standards for silver are based on an analysis of argyria occurrence (discoloration of the skin, a cosmetic condition) from the 1930s and include studies that considered nanosilver materials. The environmental standards on the other hand are based on ionic silver and may need to be re-evaluated based on recent findings that most silver in the environment, regardless of the original silver form, is present in the form of small clusters or nanoparticles. The implications of this analysis for policy of nanosilver is that it would be a mistake for regulators to ignore the accumulated knowledge of our scientific and regulatory heritage in a bid to declare nanosilver materials as new chemicals, with unknown properties and automatically harmful simply on the basis of a change in nomenclature to the term "nano".

Sorption, Solubility, Bond Strength and Hardness of Denture Soft Lining Incorporated with Silver Nanoparticles

PubMed Central

Chladek, Grzegorz; Kasperski, Jacek; Barszczewska-Rybarek, Izabela; Żmudzki, Jarosław

2013-01-01

The colonization of denture soft lining material by oral fungi can result in infections and stomatitis of oral tissues. In this study, 0 ppm to 200 ppm of silver nanoparticles was incorporated as an antimicrobial agent into composites to reduce the microbial colonization of lining materials. The effect of silver nanoparticle incorporation into a soft lining material on the sorption, solubility, hardness (on the Shore A scale) and tensile bond strength of the composites was investigated. The data were statistically analyzed using two-way ANOVA and Newman-Keuls post hoc tests or the chi-square Pearson test at the p < 0.05 level. An increase in the nanosilver concentration resulted in a decrease in hardness, an increase in sorption and solubility, a decrease in bond strength and a change in the failure type of the samples. The best combination of bond strength, sorption, solubility and hardness with antifungal efficacy was achieved for silver nanoparticle concentrations ranging from 20 ppm to 40 ppm. These composites did not show properties worse than those of the material without silver nanoparticles and exhibited enhanced in vitro antifungal efficiency. PMID:23271371

Silver oxide sorbent for carbon dioxide

NASA Technical Reports Server (NTRS)

Colombo, G. V.

1974-01-01

Material can be regenerated at least 20 times by heating at 250 C. Sorbent is compatible with environment of high humidity; up to 20% by weight of carbon dioxide can be absorbed. Material is prepared from silver carbonate, potassium hydroxide or carbonate, and sodium silicate.

40 CFR 437.1 - General applicability.

Code of Federal Regulations, 2010 CFR

2010-07-01

... centralized silver recovery from used photographic or x-ray materials activities. The discharge resulting from centralized silver recovery from used photographic or x-ray materials that is treated at a CWT facility along... Nickel Subcategory), Subpart X (Secondary Precious Metals Subcategory), Subpart Z (Secondary Tantalum...

40 CFR 437.1 - General applicability.

Code of Federal Regulations, 2011 CFR

2011-07-01

... centralized silver recovery from used photographic or x-ray materials activities. The discharge resulting from centralized silver recovery from used photographic or x-ray materials that is treated at a CWT facility along... Nickel Subcategory), subpart X (Secondary Precious Metals Subcategory), subpart Z (Secondary Tantalum...

Searching for “Defect-Tolerant” Photovoltaic Materials: Combined Theoretical and Experimental Screening

DOE PAGES

Brandt, Riley E.; Poindexter, Jeremy R.; Gorai, Prashun; ...

2017-05-09

Recently, we and others have proposed screening criteria for 'defect-tolerant' photovoltaic (PV) absorbers, identifying several classes of semiconducting compounds with electronic structures similar to those of hybrid lead-halide perovskites. In this work, we reflect on the accuracy and prospects of these new design criteria through a combined experimental and theoretical approach. We construct a model to extract photoluminescence lifetimes of six of these candidate PV absorbers, including four (InI, SbSI, SbSeI, and BiOI) for which time-resolved photoluminescence has not been previously reported. The lifetimes of all six candidate materials exceed 1 ns, a threshold for promising early stage PV devicemore » performance. However, there are variations between these materials, and none achieve lifetimes as high as those of the hybrid lead-halide perovskites, suggesting that the heuristics for defect-tolerant semiconductors are incomplete. Here, we explore this through first-principles point defect calculations and Shockley-Read-Hall recombination models to describe the variation between the measured materials. In light of these insights, we discuss the evolution of screening criteria for defect tolerance and high-performance PV materials.« less

Copper-Substituted Lead Perovskite Materials Constructed with Different Halides for Working (CH3NH3)2CuX4-Based Perovskite Solar Cells from Experimental and Theoretical View.

PubMed

Elseman, Ahmed Mourtada; Shalan, Ahmed Esmail; Sajid, Sajid; Rashad, Mohamed Mohamed; Hassan, Ali Mostafa; Li, Meicheng

2018-04-11

Toxicity and chemical instability issues of halide perovskites based on organic-inorganic lead-containing materials still remain as the main drawbacks for perovskite solar cells (PSCs). Herein, we discuss the preparation of copper (Cu)-based hybrid materials, where we replace lead (Pb) with nontoxic Cu metal for lead-free PSCs, and investigate their potential toward solar cell applications based on experimental and theoretical studies. The formation of (CH 3 NH 3 ) 2 CuX 4 [(CH 3 NH 3 ) 2 CuCl 4 , (CH 3 NH 3 ) 2 CuCl 2 I 2 , and (CH 3 NH 3 ) 2 CuCl 2 Br 2 ] was discussed in details. Furthermore, it was found that chlorine (Cl - ) in the structure is critical for the stabilization of the formed compounds. Cu-based perovskite-like materials showed attractive absorbance features extended to the near-infrared range, with appropriate band gaps. Green photoluminescence of these materials was obtained because of Cu + ions. The power conversion efficiency was measured experimentally and estimated theoretically for different architectures of solar cell devices.

All-Solid-State Mechanochemical Synthesis and Post-Synthetic Transformation of Inorganic Perovskite-type Halides.

PubMed

Pal, Provas; Saha, Sujoy; Banik, Ananya; Sarkar, Arka; Biswas, Kanishka

2018-02-06

All-inorganic and hybrid perovskite type halides are generally synthesized by solution-based methods, with the help of long chain organic capping ligands, complex organometallic precursors, and high boiling organic solvents. Herein, a room temperature, solvent-free, general, and scalable all-solid-state mechanochemical synthesis is demonstrated for different inorganic perovskite type halides, with versatile structural connectivity in three (3D), two (2D), and zero (0D) dimensions. 3D CsPbBr 3 , 2D CsPb 2 Br 5 , 0D Cs 4 PbBr 6 , 3D CsPbCl 3 , 2D CsPb 2 Cl 5 , 0D Cs 4 PbCl 6 , 3D CsPbI 3 , and 3D RbPbI 3 have all been synthesized by this method. The all-solid-state synthesis is materialized through an inorganic retrosynthetic approach, which directs the decision on the solid-state precursors (e.g., CsX and PbX 2 (X=Cl/Br/I) with desired stoichiometric ratios. Moreover, post-synthetic structural transformations from 3D to 2D and 0D perovskite halides were performed by the same mechanochemical synthetic approach at room temperature. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reversible photo-induced trap formation in mixed-halide hybrid perovskites for photovoltaics† †Electronic supplementary information (ESI) available: Experimental details, PL, PDS spectra and XRD patterns. See DOI: 10.1039/c4sc03141e Click here for additional data file.

PubMed Central

Hoke, Eric T.; Slotcavage, Daniel J.; Dohner, Emma R.; Bowring, Andrea R.

2015-01-01

We report on reversible, light-induced transformations in (CH3NH3)Pb(BrxI1–x)3. Photoluminescence (PL) spectra of these perovskites develop a new, red-shifted peak at 1.68 eV that grows in intensity under constant, 1-sun illumination in less than a minute. This is accompanied by an increase in sub-bandgap absorption at ∼1.7 eV, indicating the formation of luminescent trap states. Light soaking causes a splitting of X-ray diffraction (XRD) peaks, suggesting segregation into two crystalline phases. Surprisingly, these photo-induced changes are fully reversible; the XRD patterns and the PL and absorption spectra revert to their initial states after the materials are left for a few minutes in the dark. We speculate that photoexcitation may cause halide segregation into iodide-rich minority and bromide-enriched majority domains, the former acting as a recombination center trap. This instability may limit achievable voltages from some mixed-halide perovskite solar cells and could have implications for the photostability of halide perovskites used in optoelectronics. PMID:28706629

First-principles thermodynamics study of phase stability in inorganic halide perovskite solid solutions

NASA Astrophysics Data System (ADS)

Bechtel, Jonathon S.; Van der Ven, Anton

2018-04-01

Halide substitution gives rise to a tunable band gap as a function of composition in halide perovskite materials. However, photoinduced phase segregation, observed at room temperature in mixed halide A Pb (IxBr1-x) 3 systems, limits open circuit voltages and decreases photovoltaic device efficiencies. We investigate equilibrium phase stability of orthorhombic P n m a γ -phase CsM (XxY1-x) 3 perovskites where M is Pb or Sn, and X and Y are Br, Cl, or I. Finite-temperature phase diagrams are constructed using a cluster expansion effective Hamiltonian parameterized from first-principles density-functional-theory calculations. Solid solution phases for CsM (IxBr1-x) 3 and CsM (BrxCl1-x) 3 are predicted to be stable well below room temperature while CsM (IxCl1-x) 3 systems have miscibility gaps that extend above 400 K. The height of the miscibility gap correlates with the difference in volume between end members. Also layered ground states are found on the convex hull at x =2 /3 for CsSnBr2Cl ,CsPbI2Br , and CsPbBrCl2. The impact of these ground states on the finite temperature phase diagram is discussed in the context of the experimentally observed photoinduced phase segregation.

Electroless silver plating on PET fabric initiated by in situ reduction of polyaniline

NASA Astrophysics Data System (ADS)

Mu, Shipeng; Xie, Huayang; Wang, Wei; Yu, Dan

2015-10-01

Novel electroless silver plating poly(ethylene terephthalate) (PET) fabric was prepared by a two-step procedure. In the first step, the in situ polymerized polyaniline (PANI) occurred on the fabric surface in the presence of ammonium persulfate (APS). Then, Ag(0) species reduced from silver nitrate (AgNO3) by in situ reduction of PANI were used as catalyst to initiate electroless silver plating. Hence, this composite material was prepared by conductive polymer combined with electroless plating. The silver layer on PET fabric surface was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDX) as well as X-ray photoelectron spectroscopy (XPS). The results showed that the silver layer was plated uniformly and compactly with surface resistance about 0.1 Ω/sq on average. The shielding effectiveness (SE) of silver-plated PET fabric was around 50-90 dB, which was considered to have potential applications in electromagnetic shielding materials. Thermogravimetric (TG) analysis was carried out to study thermal stability. The antibacterial tests demonstrated that the silver-plated fabric exhibited excellent antibacterial activity against Staphylococcus aureus and Escherichia coli both with 100%.

A pilot study of the marginal adaptation and surface morphology of glass-cermet cements.

PubMed

Chu, C H; King, N M; Lee, A M; Yiu, C K; Wei, S H

1996-07-01

This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months.

Signal intensity enhancement of laser ablated volume holograms

NASA Astrophysics Data System (ADS)

Versnel, J. M.; Williams, C.; Davidson, C. A. B.; Wilkinson, T. D.; Lowe, C. R.

2017-11-01

Conventional volume holographic gratings (VHGs) fabricated in photosensitive emulsions such as gelatin containing silver salts enable the facile visualization of the holographic image in ambient lighting. However, for the fabrication of holographic sensors, which require more defined and chemically-functionalised polymer matrices, laser ablation has been introduced to create the VHGs and thereby broaden their applications, although the replay signal can be challenging to detect in ambient lighting. When traditional photochemical bleaching solutions used to reduce light scattering and modulate refractive index within the VHG are applied to laser ablated volume holographic gratings, these procedures decrease the holographic peak intensity. This is postulated to occur because both light and dark fringes contain a proportion of metal particles, which upon solubilisation are converted immediately to silver iodide, yielding no net refractive index modulation. This research advances a hypothesis that the reduced intensity of holographic replay signals is linked to a gradient of different sized metal particles within the emulsion, which reduces the holographic signal and may explain why traditional bleaching processes result in a reduction in intensity. In this report, a novel experimental protocol is provided, along with simulations based on an effective medium periodic 1D stack, that offers a solution to increase peak signal intensity of holographic sensors by greater than 200%. Nitric acid is used to etch the silver nanoparticles within the polymer matrix and is thought to remove the smaller particles to generate more defined metal fringes containing a soluble metal salt. Once the grating efficiency has been increased, this salt can be converted to a silver halide, to modulate the refractive index and increase the intensity of the holographic signal. This new protocol has been tested in a range of polymer chemistries; those containing functional groups that help to stabilize the metal nanoparticles within the matrix yield more intense holographic signals as the integrity of the fringe is more protected with increasing metal solubility.

Metal thin-film optical polarizers for space applications, phase 2

NASA Technical Reports Server (NTRS)

Slocum, Robert E.

1991-01-01

A light polarizing material was developed for wavelengths in the visible and near infrared spectral band (400 to 3,000 nm). The material is comprised of ellipsoidal silver particles uniformly distributed and aligned on the surface of an optical material. A method is set forth for making polarizing material by evaporatively coating a smooth glass surface with ellipsoidal silver particles. The wavelength of peak absorption is chosen by selecting the aspect ratio of the ellipsoidal metal particles and the refractive index of the material surrounding the metal particles. The wavelength of peak absorption can be selected to fall at a desired wavelength in the range from 400 to 3,000 nm by control of the deposition process. This method is demonstrated by evaporative deposition of silver particles directly on to a smooth optical surface. By applying a multilayer silver coating of a glass disc, a contrast of greater than 40,000 was achieved at 590 nm. A polarizing filter was designed, fabricated, and assembled which achieved contrast of 100,00 at 59 nm and can serve as a replacement for crystal polarizers.

The role of silver in self-lubricating coatings for use at extreme temperatures

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1985-01-01

The advantages and disadvantages of elemental silver as a tribological material are discussed. It is demonstrated that the relatively high melting point of 961 deg C, softness, marked plasticity, and thermochemical stability of silver combine to make this metal useful in thin film solid lubricant coatings over a wide temperature range. Disadvantages of silver during sliding, except when used as a thin film, are shown to be gross ploughing due to plastic deformation under load with associated high friction and excessive transfer to counterface surfaces. This transfer generates an irregular surface topography with consequent undesirable changes in bearing clearance distribution. Research to overcome these disadvantages of element silver is described. A comparison is made of the tribological behavior of pure silver with that of silver formulated with other metals and high-temperature solid lubricants. The composite materials are prepared by co-depositing the powdered components with an airbrush followed by furnace heat treatment or by plasma-spraying. Composite coatings were formulated which are shown to be self-lubricating over repeated, temperature cycles from low temperature to about 900 deg C.

The use of silver in self-lubricating coatings for extreme temperatures

NASA Technical Reports Server (NTRS)

Sliney, H. E.

1986-01-01

The advantages and disadvantages of elemental silver as a tribological material are discussed. It is demonstrated that the relatively high melting point of 961 deg C, softness, marked plasticity, and thermochemical stability of silver combine to make this metal useful in thin film solid lubricant coatings over a wide temperature range. Disadvantages of silver during sliding, except when used as a thin film, are shown to be gross ploughing due to plastic deformation under load with associated high friction and excessive transfer to counterface surfaces. This transfer generates an irregular surface topography with consequent undesirable changes in bearing clearance distribution. Research to overcome these disadvantages of element silver is described. A comparison is made of the tribological behavior of pure silver with that of silver formulated with other metals and high-temperature solid lubricants. The composite materials are prepared by co-depositing the powdered components with an airbrush followed by furnace heat treatment or by plasma-spraying. Composite coatings were formulated which are shown to be self-lubricating over repeated, temperature cycles from low temperature to about 900 deg C.

Study on Silver-plated Molybdenum Interconnected Materials for LEO Solar Cell Array

NASA Astrophysics Data System (ADS)

Zhu, Jia-jun; Hu, Yu-hao; Xu, Meng; Yang, Wu-lin; Fu, Li-cai; Li, De-yi; Zhou, Ling-ping

2017-09-01

Atomic oxygen (AO) is one of the most important environmental factors that affected the performance of low earth orbit spacecraft in orbit. In which, silver was the most common materials as the interconnected materials. However, with the poor AO resistance of silver, the interconnectors could be failure easier, and the lifetime of the spacecraft was also reduced. In this paper, the silver-plated molybdenum interconnected materials made by Ag thin films deposited on the Mo foils by vacuum deposition methods was studied. And the effects of the preparation process on the micro-structure of the Ag thin films, the interfacial adhesive strength and the electrical conductivity of the composites were investigated. It was found that the Ag thin films deposited on the Mo substrates coated the Ag thin films by ion beam assisted deposition(IBAD) methods exhibited a perfectly (200) preferred orientation. The interfacial adhesive strength had been increased to 18.58MPa. And the composites also have excellent electrical performance.

Sequestration of radioactive iodine in silver-palladium phases in commercial spent nuclear fuel

NASA Astrophysics Data System (ADS)

Buck, Edgar C.; Mausolf, Edward J.; McNamara, Bruce K.; Soderquist, Chuck Z.; Schwantes, Jon M.

2016-12-01

Radioactive iodine is the Achilles' heel in the design for the safe geological disposal of spent uranium oxide (UO2) nuclear fuel. Furthermore, iodine's high volatility and aqueous solubility were mainly responsible for the high early doses released during the accident at Fukushima Daiichi in 2011. Studies Kienzler et al., however, have indicated that the instant release fraction (IRF) of radioiodine (131/129I) does not correlate directly with increasing fuel burn-up. In fact, there is a peak in the release of iodine at around 50-60 MW d/kgU, and with increasing burn-up, the IRF of 131/129I decreases. The reasons for this decrease have not fully been understood. We have performed microscopic analysis of chemically processed high burn-up UO2 fuel (80 MW d/kgU) and have found recalcitrant nano-particles containing, Pd, Ag, I, and Br, possibly consistent with a high pressure phase of silver iodide in the undissolved residue. It is likely that increased levels of Ag and Pd from 239Pu fission in high burnup fuels leads to the formation of these metal halides. The occurrence of these phases in UO2 nuclear fuels may reduce the impact of long-lived 129I on the repository performance assessment calculations.

Epitaxial growth of CoO films on semiconductor and metal substrates by constructing a complex heterostructure

NASA Astrophysics Data System (ADS)

Entani, S.; Kiguchi, M.; Saiki, K.; Koma, A.

2003-01-01

Epitaxial growth of CoO films was studied using reflection high-energy electron diffraction (RHEED), electron energy loss spectroscopy (EELS), ultraviolet photoelectron spectroscopy (UPS) and Auger electron spectroscopy (AES). The RHEED results indicated that an epitaxial CoO film grew on semiconductor and metal substrates (CoO (0 0 1)∥GaAs (0 0 1), Cu (0 0 1), Ag (0 0 1) and [1 0 0]CoO∥[1 0 0] substrates) by constructing a complex heterostructure with two alkali halide buffer layers. The AES, EELS and UPS results showed that the grown CoO film had almost the same electronic structure as bulk CoO. We could show that use of alkali halide buffer layers was a good way to grow metal oxide films on semiconductor and metal substrates in an O 2 atmosphere. The alkali halide layers not only works as glue to connect very dissimilar materials but also prevents oxidation of metal and semiconductor substrates.

Mid-infrared emission and Judd-Ofelt analysis of Dy3+-doped infrared Ga-Sb-S and Ga-Sb-S-PbI2 chalcohalide glasses

NASA Astrophysics Data System (ADS)

Guo, Jixiao; Jiao, Qing; He, Xiaolong; Guo, Hansong; Tong, Jianghao; Zhang, Zhihang; Jiang, Fuchao; Wang, Guoxiang

2018-03-01

Dy3+-doped Ga-Sb-S and Ga-Sb-S-PbI2 chalcohalide glasses were prepared by traditional melt quenching method. The effect of halide PbI2 on the physical and optical properties of Dy3+ ions was investigated. The density and ionic concentration of the host sample increased with the introduction of PbI2 halides, whereas the refractive index at 1.55 μm decreased. The Judd-Ofelt parameters showed that Ω2 increased in PbI2-modified glass, whereas the Ω6 value showed the opposite tendency. Infrared emission spectrum also showed that the intensity increased with PbI2 addition, and considerable enhancement at 2.8 μm was observed in the mid-infrared region. The halide PbI2 promoted the reduction of phonon energy of the host and the improvement of the laser pump efficiency, which led to the construction of optimized infrared glass materials for optical applications.

Process for separating dissolved solids from a liquid using an anti-solvent and multiple effect evaporators

DOEpatents

Daniels, Edward J.; Jody, Bassam J.; Bonsignore, Patrick V.

1994-01-01

A process and system for treating aluminum salt cake containing water soluble halide salts by contacting the salt cake with water to dissolve water soluble halide salts forming a saturated brine solution. Transporting a portion of about 25% of the saturated brine solution to a reactor and introducing into the saturated brine solution at least an equal volume of a water-miscible low-boiling organic material such as acetone to precipitate a portion of the dissolved halide salts forming a three-phase mixture of an aqueous-organic-salt solution phase and a precipitated salt phase and an organic rich phase. The precipitated salt phase is separated from the other phases and the organic rich phase is recycled to the reactor. The remainder of the saturated brine solution is sent to a multiple effect evaporator having a plurality of stages with the last stage thereof producing low grade steam which is used to boil off the organic portion of the solution which is recycled.

Pressure-Induced Structural Evolution and Band Gap Shifts of Organometal Halide Perovskite-Based Methylammonium Lead Chloride.

PubMed

Wang, Lingrui; Wang, Kai; Xiao, Guanjun; Zeng, Qiaoshi; Zou, Bo

2016-12-15

Organometal halide perovskites are promising materials for optoelectronic devices. Further development of these devices requires a deep understanding of their fundamental structure-property relationships. The effect of pressure on the structural evolution and band gap shifts of methylammonium lead chloride (MAPbCl 3 ) was investigated systematically. Synchrotron X-ray diffraction and Raman experiments provided structural information on the shrinkage, tilting distortion, and amorphization of the primitive cubic unit cell. In situ high pressure optical absorption and photoluminescence spectra manifested that the band gap of MAPbCl 3 could be fine-tuned to the ultraviolet region by pressure. The optical changes are correlated with pressure-induced structural evolution of MAPbCl 3 , as evidenced by band gap shifts. Comparisons between Pb-hybrid perovskites and inorganic octahedra provided insights on the effects of halogens on pressure-induced transition sequences of these compounds. Our results improve the understanding of the structural and optical properties of organometal halide perovskites.

Two-Dimensional Halide Perovskites: Tuning Electronic Activities of Defects

DOE PAGES

Liu, Yuanyue; Xiao, Hai; Goddard, William A.

2016-04-21

Two-dimensional (2D) halide perovskites are emerging as promising candidates for nanoelectronics and optoelectronics. To realize their full potential, it is important to understand the role of those defects that can strongly impact material properties. In contrast to other popular 2D semiconductors (e.g., transition metal dichalcogenides MX 2) for which defects typically induce harmful traps, we show that the electronic activities of defects in 2D perovskites are significantly tunable. For example, even with a fixed lattice orientation one can change the synthesis conditions to convert a line defect (edge or grain boundary) from electron acceptor to inactive site without deep gapmore » states. Here, we show that this difference originates from the enhanced ionic bonding in these perovskites compared with MX 2. The donors tend to have high formation energies and the harmful defects are difficult to form at a low halide chemical potential. Thus, we unveil unique properties of defects in 2D perovskites and suggest practical routes to improve them.« less

Process for separating dissolved solids from a liquid using an anti-solvent and multiple effect evaporators

DOEpatents

Daniels, E.J.; Jody, B.J.; Bonsignore, P.V.

1994-07-19

A process and system are disclosed for treating aluminum salt cake containing water soluble halide salts by contacting the salt cake with water to dissolve water soluble halide salts forming a saturated brine solution. Transporting a portion of about 25% of the saturated brine solution to a reactor and introducing into the saturated brine solution at least an equal volume of a water-miscible low-boiling organic material such as acetone to precipitate a portion of the dissolved halide salts forming a three-phase mixture of an aqueous-organic-salt solution phase and a precipitated salt phase and an organic rich phase. The precipitated salt phase is separated from the other phases and the organic rich phase is recycled to the reactor. The remainder of the saturated brine solution is sent to a multiple effect evaporator having a plurality of stages with the last stage thereof producing low grade steam which is used to boil off the organic portion of the solution which is recycled. 3 figs.

Silver nanoprisms/silicone hybrid rubber materials and their optical limiting property to femtosecond laser

NASA Astrophysics Data System (ADS)

Li, Chunfang; Liu, Miao; Jiang, Nengkai; Wang, Chunlei; Lin, Weihong; Li, Dongxiang

2017-08-01

Optical limiters against femtosecond laser are essential for eye and sensor protection in optical processing system with femtosecond laser as light source. Anisotropic Ag nanoparticles are expected to develop into optical limiting materials for femtosecond laser pulses. Herein, silver nanoprisms are prepared and coated by silica layer, which are then doped into silicone rubber to obtain hybrid rubber sheets. The silver nanoprisms/silicone hybrid rubber sheets exhibit good optical limiting property to femtosecond laser mainly due to nonlinear optical absorption.

Durability of reflector materials in the space environment

NASA Technical Reports Server (NTRS)

Whitaker, Ann F.; Finckenor, Miria M.; Edwards, David; Kamenetzky, Rachel R.; Linton, Roger C.

1995-01-01

Various reflector configurations were flown as part of the Long Duration Exposure Facility (LDEF) A0171 experiment. These reflectors consisted of nickel substrates with aluminum, enhanced aluminum (multiple layers of aluminum and silver), silver, and silver alloy coatings with glassy ceramic overcoatings. These samples have been evaluated for changes in reflectance due to 5.8 years in the space environment. The reflector materials have also been evaluated using angstrometer, Rutherford backscattering (RBS), and electron spectroscopy for chemical analysis (ESCA) techniques.

Doped biocompatible layers prepared by laser

NASA Astrophysics Data System (ADS)

Jelínek, M.; Weiserová, M.; Kocourek, T.; Jurek, K.; Strnad, J.

2010-03-01

The contribution deals with KrF laser synthesis and study of doped biocompatible materials with focus on diamond-like carbon (DLC) and hydroxyapatite (HA). Overview of materials used for dopation is given. Experimental results of study of HA layers doped with silver are presented. Films properties were characterized using profilometer, SEM, WDX, XRD and optical transmission. Content of silver in layers moved from 0.06 to 13.7 at %. The antibacterial properties of HA, silver and doped HA layers were studied in vivo using Escherichia coli cells.

Self-regulation mechanism for charged point defects in hybrid halide perovskites

DOE PAGES

Walsh, Aron; Scanlon, David O.; Chen, Shiyou; ...

2014-12-11

Hybrid halide perovskites such as methylammonium lead iodide (CH 3NH 3PbI 3) exhibit unusually low free-carrier concentrations despite being processed at low-temperatures from solution. We demonstrate, through quantum mechanical calculations, that an origin of this phenomenon is a prevalence of ionic over electronic disorder in stoichiometric materials. Schottky defect formation provides a mechanism to self-regulate the concentration of charge carriers through ionic compensation of charged point defects. The equilibrium charged vacancy concentration is predicted to exceed 0.4 % at room temperature. Furthermore, this behavior, which goes against established defect conventions for inorganic semiconductors, has implications for photovoltaic performance.

Lithium-aluminum-magnesium electrode composition

DOEpatents

Melendres, Carlos A.; Siegel, Stanley

1978-01-01

A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

Hybrid Lead Halide Layered Perovskites with Silsesquioxane Interlayers.

PubMed

Kataoka, Sho; Kaburagi, Wako; Mochizuki, Hiroyuki; Kamimura, Yoshihiro; Sato, Kazuhiko; Endo, Akira

2018-01-01

Hybrid organic-lead halide perovskites exhibit remarkable properties as semiconductors and light absorbers. Here, we report the formation of silsesquioxane-lead halide hybrid layered perovskites. We prepared silsesquioxane with a cubic cage-like structure and fabricated hybrid silsesquioxane-lead halide layered perovskites in a self-assembled manner. It is demonstrated that the silsesquioxane maintain their cage-like structure between lead halide perovskite layers. The silsesquioxane-lead halide perovskites also show excitonic absorption and emission in the visible light region similar to typical lead halide layered perovskites.

Silver coated aluminium microrods as highly colloidal stable SERS platforms.

PubMed

Pazos-Perez, Nicolas; Borke, Tina; Andreeva, Daria V; Alvarez-Puebla, Ramon A

2011-08-01

We report on the fabrication of a novel material with the ability to remain in solution even under the very demanding conditions required for structural and dynamic characterization of biomacromolecule assays. This stability is provided by the increase in surface area of a low density material (aluminium) natively coated with a very hydrophilic surface composed of aluminium oxide (Al(2)O(3)) and metallic silver nanoparticles. Additionally, due to the dense collection of active hot spots on their surface, this material offers higher levels of SERS intensity as compared with the same free and aggregated silver nanoparticles. This journal is © The Royal Society of Chemistry 2011

Interesting electrochemical properties of novel three-dimensional Ag3PO4 tetrapods as a new super capacitor electrode material

NASA Astrophysics Data System (ADS)

Li, Shouguang; Teng, Fei; Chen, Mindong; Li, Na; Hua, Xia; Wang, Kai; Li, Min

2014-05-01

The novel three-dimensional (3D) silver phosphate tetrapods (TA) are synthesized and employed as a super capacitor electrode material. The electrochemical properties are investigated by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). It is interesting that compared with irregular silver phosphate particles (IA), TA shows a higher capacitance (250 vs. 160 F g-1), and a higher coulombic efficiency (80% vs. 74%), which is mainly ascribed to the 3D microstructure and its high conductivity. To the best of our knowledge, this is the first report on silver phosphate as a super capacitor material.

Functionalization of textiles with silver and zinc oxide nanoparticles

NASA Astrophysics Data System (ADS)

Pulit-Prociak, Jolanta; Chwastowski, Jarosław; Kucharski, Arkadiusz; Banach, Marcin

2016-11-01

The paper presents a method for functionalization of textile materials using fabric dyes modified with silver or zinc oxide nanoparticles. Embedding of these nanoparticles into the structure of other materials makes that the final product is characterized by antimicrobial properties. Indigo and commercially available dye were involved in studies. It is worth to note that silver nanoparticles were obtained in-situ in the reaction of preparing indigo dye and in the process of preparing commercial dye baths. Such a method allows reducing technological steps. The modified dyes were used for dyeing of cotton fibers. The antimicrobial properties of final textile materials were studied. Saccharomyces cerevisiae strain was used in microbiological test. The results confirmed biocidal activity of prepared materials.

Ferroelectric large polarons

NASA Astrophysics Data System (ADS)

Miyata, Kiyoshi; Zhu, X.-Y.

2018-05-01

Kiyoshi Miyata and X.-Y. Zhu analyse the ferroelectric-like dielectric response of lead halide perovskites in the terahertz region and discuss the potential role of polar nanodomains in accounting for the defect tolerance and low recombination rates of these materials.

Amorphous and nanocrystalline luminescent Si and Ge obtained via a solid-state chemical metathesis synthesis route

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillan, Paul F.; Gryko, Jan; Bull, Craig

A new solid-state metathesis synthesis route was applied to obtain bulk samples of amorphous or microcrystalline Si and Ge. The method involves reaction of Zintl phases such as NaSi or NaGe, with ammonium or metal (e.g., CuCl, CoBr{sub 2}) halides. The driving force for the solid-state reaction is provided by the formation of alkali halides and the transition metals or metal silicides, or gaseous ammonia and hydrogen. The semiconductors were purified by washing to remove other solid products. The amorphous semiconductors were obtained in bulk form from reactions carried out at 200-300{sup o}C. Syntheses at higher temperatures gave rise tomore » microcrystalline semiconductors, or to micro-/nanocrystalline particles contained within the amorphous material. Similar crystalline/amorphous composites were obtained after heat treatment of bulk amorphous materials.« less

Highly Controlled Codeposition Rate of Organolead Halide Perovskite by Laser Evaporation Method.

PubMed

Miyadera, Tetsuhiko; Sugita, Takeshi; Tampo, Hitoshi; Matsubara, Koji; Chikamatsu, Masayuki

2016-10-05

Organolead-halide perovskites can be promising materials for next-generation solar cells because of its high power conversion efficiency. The method of precise fabrication is required because both solution-process and vacuum-process fabrication of the perovskite have problems of controllability and reproducibility. Vacuum deposition process was expected to achieve precise control; however, vaporization of amine compound significantly degrades the controllability of deposition rate. Here we achieved the reduction of the vaporization by implementing the laser evaporation system for the codeposition of perovskite. Locally irradiated continuous-wave lasers on the source materials realized the reduced vaporization of CH 3 NH 3 I. The deposition rate was stabilized for several hours by adjusting the duty ratio of modulated laser based on proportional-integral control. Organic-photovoltaic-type perovskite solar cells were fabricated by codeposition of PbI 2 and CH 3 NH 3 I. A power-conversion efficiency of 16.0% with reduced hysteresis was achieved.

Hydrophobic Organic Hole Transporters for Improved Moisture Resistance in Metal Halide Perovskite Solar Cells.

PubMed

Leijtens, Tomas; Giovenzana, Tommaso; Habisreutinger, Severin N; Tinkham, Jonathan S; Noel, Nakita K; Kamino, Brett A; Sadoughi, Golnaz; Sellinger, Alan; Snaith, Henry J

2016-03-09

Solar cells based on organic-inorganic perovskite semiconductor materials have recently made rapid improvements in performance, with the best cells performing at over 20% efficiency. With such rapid progress, questions such as cost and solar cell stability are becoming increasingly important to address if this new technology is to reach commercial deployment. The moisture sensitivity of commonly used organic-inorganic metal halide perovskites has especially raised concerns. Here, we demonstrate that the hygroscopic lithium salt commonly used as a dopant for the hole transport material in perovskite solar cells makes the top layer of the devices hydrophilic and causes the solar cells to rapidly degrade in the presence of moisture. By using novel, low cost, and hydrophobic hole transporters in conjunction with a doping method incorporating a preoxidized salt of the respective hole transporters, we are able to prepare efficient perovskite solar cells with greatly enhanced water resistance.

Effect of Carrier Thermalization Dynamics on Light Emission and Amplification in Organometal Halide Perovskites.

PubMed

Chen, Kai; Barker, Alex J; Morgan, Francis L C; Halpert, Jonathan E; Hodgkiss, Justin M

2015-01-02

The remarkable rise of organometal halide perovskites as solar photovoltaic materials has been followed by promising developments in light-emitting devices, including lasers. Here we present unique insights into the processes leading to photon emission in these materials. We employ ultrafast broadband photoluminescence (PL) and transient absorption spectroscopies to directly link density dependent ultrafast charge dynamics to PL. We find that exceptionally strong PL at the band edge is preceded by thermalization of free charge carriers. Short-lived PL above the band gap is clear evidence of nonexcitonic emission from hot carriers, and ultrafast PL depolarization confirms that uncorrelated charge pairs are precursors to photon emission. Carrier thermalization has a profound effect on amplified stimulated emission at high fluence; the delayed onset of optical gain we resolve within the first 10 ps and the unusual oscillatory behavior are both consequences of the kinetic interplay between carrier thermalization and optical gain.

Metal halide arc discharge lamp having short arc length

NASA Technical Reports Server (NTRS)

Muzeroll, Martin E. (Inventor)

1994-01-01

A metal halide arc discharge lamp includes a sealed light-transmissive outer jacket, a light-transmissive shroud located within the outer jacket and an arc tube assembly located within the shroud. The arc tube assembly includes an arc tube, electrodes mounted within the arc tube and a fill material for supporting an arc discharge. The electrodes have a spacing such that an electric field in a range of about 60 to 95 volts per centimeter is established between the electrodes. The diameter of the arc tube and the spacing of the electrodes are selected to provide an arc having an arc diameter to arc length ratio in a range of about 1.6 to 1.8. The fill material includes mercury, sodium iodide, scandium tri-iodide and a rare gas, and may include lithium iodide. The lamp exhibits a high color rendering index, high lumen output and high color temperature.

New Cathode Material for High Energy-Density Batteries,

DTIC Science & Technology

Semiconductive metal halides are under investigation as cathode materials for ambient-temperature lithium cells. N-type cadmium fluoride and zinc...fluoride were further characterized as electrodes limited by cathodic passivation in a lithium perchlorate-propylene carbonate electrolyte. The...discharge of cadmium fluoride occurred without passivation, however, in a tetramethylammonium hexafluorophosphate solution in the same solvent. The result

Molten-Salt-Based Growth of Group III Nitrides

DOEpatents

Waldrip, Karen E.; Tsao, Jeffrey Y.; Kerley, Thomas M.

2008-10-14

A method for growing Group III nitride materials using a molten halide salt as a solvent to solubilize the Group-III ions and nitride ions that react to form the Group III nitride material. The concentration of at least one of the nitride ion or Group III cation is determined by electrochemical generation of the ions.

Conservation of Photographic Print Collections.

ERIC Educational Resources Information Center

Swan, Alice

1981-01-01

Provides specific information on varying photographic materials and processes to aid archivists and curators in preserving photograph collections. Preservation problems related to major types of silver prints on paper (salt, albumen, collodion, gelatin) and to the silver image (oxidation, silver sulfide) are covered. Twenty references are cited.…

Synthesis of dextrin-stabilized colloidal silver nanoparticles and their application as modifiers of cement mortar.

PubMed

Konował, Emilia; Sybis, Marta; Modrzejewska-Sikorska, Anna; Milczarek, Grzegorz

2017-11-01

Various commercial dextrins were used as reducing and stabilizing agents for a novel one-step synthesis of silver nanoparticles from ammonia complexes of silver ions. As a result, stable colloids of silver were formed during the reaction with the particle size being the function of the dextrin type. The obtained colloids were characterized by UV-vis spectrophotometry, size distribution (using Non-Invasive Backscatter optics) and transmission electron microscopy (TEM). The achieved results clearly indicate the possibility of low-cost production of large quantities of colloidal silver nanoparticles using materials derived from renewable sources. The resulting silver colloids can be used for different purposes, e.g. as bactericidal agents. Combination of the aforementioned properties of nanosilver particles with plasticizing properties of dextrin enables to obtain cement mortars with increased workability and enhanced compressive strength. Moreover, the obtained material is also characterized by increased immunity to adverse impact of microorganisms. Copyright © 2017 Elsevier B.V. All rights reserved.

Durable metallized polymer mirror

DOEpatents

Schissel, Paul O.; Kennedy, Cheryl E.; Jorgensen, Gary J.; Shinton, Yvonne D.; Goggin, Rita M.

1994-01-01

A metallized polymer mirror construction having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate.

Highly Conductive Nano-Silver Circuits by Inkjet Printing

NASA Astrophysics Data System (ADS)

Zhu, Dongbin; Wu, Minqiang

2018-06-01

Inkjet technology has become popular in the field of printed electronics due to its superior properties such as simple processes and printable complex patterns. Electrical conductivity of the circuits is one of the key factors in measuring the performance of printed electronics, which requires great material properties and a manufactured process. With excellent conductivity and ductility, silver is an ideal material as the wire connecting components. This review summarizes the progress of conductivity studies on inkjet printed nano-silver lines, including ink composition and nanoparticle morphology, deposition of nano-silver lines with uniform and high aspect ratios, sintering mechanisms and alternative methods of thermal sintering. Finally, the research direction on inkjet printed electronics is proposed.

Clinical evaluation of glass ionomer-silver cermet restorations in primary molars: one year results.

PubMed

Hung, T W; Richardson, A S

1990-03-01

Using the half mouth technique, 33 silver amalgam (Dispersalloy) and 40 glass ionomer (Ketec silver) restorations were placed in the primary molars of children aged five to seven years. After one year, 73 restorations were evaluated. The amalgam restorations rated 90-100 per cent alpha for anatomic form and margins with no recurrent caries or fractures. The glass ionomer restorations rated 35 to 55 per cent alpha for anatomic form and margins with 40 per cent being replaced due to fracture of the material. Within the guidelines of this study, glass ionomer silver cermet was not a suitable material for the restoration of interproximal cavities in primary molars.

Synthesis of new nanocrystal materials

NASA Astrophysics Data System (ADS)

Hassan, Yasser Hassan Abd El-Fattah

Colloidal semiconductor nanocrystals (NCs) have sparked great excitement in the scientific community in last two decades. NCs are useful for both fundamental research and technical applications in various fields owing to their size and shape-dependent properties and their potentially inexpensive and excellent chemical processability. These NCs are versatile fluorescence probes with unique optical properties, including tunable luminescence, high extinction coefficient, broad absorption with narrow photoluminescence, and photobleaching resistance. In the past few years, a lot of attention has been given to nanotechnology based on using these materials as building blocks to design light harvesting assemblies. For instant, the pioneering applications of NCs are light-emitting diodes, lasers, and photovoltaic devices. Synthesis of the colloidal stable semiconductor NCs using the wet method of the pyrolysis of organometallic and chalcogenide precursors, known as hot-injection approach, is the chart-topping preparation method in term of high quality and monodisperse sized NCs. The advancement in the synthesis of these artificial materials is the core step toward their applications in a broad range of technologies. This dissertation focuses on exploring various innovative and novel synthetic methods of different types of colloidal nanocrystals, both inorganic semiconductors NCs, also known as quantum dots (QDs), and organic-inorganic metal halide-perovskite materials, known as perovskites. The work presented in this thesis focuses on pursuing fundamental understanding of the synthesis, material properties, photophysics, and spectroscopy of these nanostructured semiconductor materials. This thesis contains 6 chapters and conclusions. Chapters 1?3 focus on introducing theories and background of the materials being synthesized in the thesis. Chapter 4 demonstrates our synthesis of colloidal linker--free TiO2/CdSe NRs heterostructures with CdSe QDs grown in the presence of TiO2 NRs using seeded--growth type colloidal injection approach. Chapter 5 explores a novel approach of directly synthesized CdSe NCs with electroactive ligands. The last Chapter focuses on a new class of perovskites. I describe my discovery of a (bottom-up) simple method to synthesize colloidally stable methyl ammonium lead halide perovskite nanocrystals seeded from high quality PbX2 NCs with a pre-targeted size. This chapter reports advances in preparation of both these materials (PbX2, and lead halide perovskite NCs).

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Seog Joon; Kuno, Masaru; Kamat, Prashant V.

Minimizing photoinduced segregation in mixed halide lead perovskites is important for achieving stable photovoltaic performance. The shift in the absorption and the rate of formation of iodide- and bromide-rich regions following visible excitation of mixed halide lead perovskites is found to strongly depend on the halide ion concentration. Slower formation and recovery rates observed in halide-deficient films indicate the involvement of defect sites in influencing halide phase segregation. At higher halide concentrations (in stoichiometric excess), segregation effects become less prominent, as evidenced by faster recovery kinetics. These results suggest that light-induced compositional segregation can be minimized in mixed halide perovskitemore » films by using excess halide ions. In conclusion, the findings from this study further reflect the importance of halide ion post-treatment of perovskite films to improve their solar cell performance.« less

Resin-modified glass ionomer cements: fluoride release and influence on Streptococcus mutans growth.

PubMed

Friedl, K H; Schmalz, G; Hiller, K A; Shams, M

1997-02-01

The aims of the present study were to measure the fluoride release of 1 glass ionomer cement, 1 cermet, 3 resin-modified glass ionomer cements and 1 compomer, and to determine the influence of each material on bacterial growth. Test specimens were eluted in saline for 180 days. Every 2 days, the specimens were transferred into fresh saline and the fluoride content of the solution was measured. Furthermore, 48-h, 14-d, 90-d, and 180-d eluates were inoculated with Streptococcus mutans and bacterial growth was recorded nephelometrically. Fluoride release dropped significantly over time for each material with values between 6.2 (Ketac-Silver) and 29.3 (Photac-Fil) ppm after 48 h to values between 0.6 (Ketac-Silver) and 1.7 (Ketac-Fil, Vitremer) ppm after 180 days. Each material reduced bacterial growth at each time of examination, but the effect decreased significantly over time with a maximum growth of 71.7% (Ketac-Fil) to 85.6% (Ketac-Silver) after 48 h and 94.7 (Vitremer) to 99.0% (Ketac-Silver) after 180 days (growth control = 100%). Both Ketac-Silver and Dyract showed a significantly lower inhibiting effect on bacterial growth than the other materials. The tested materials showed a good correlation between fluoride release and influence on bacterial growth. However, both effects dropped dramatically over the 180-days period.

Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

PubMed Central

Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

2015-01-01

Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet–visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films. PMID:26156001

Antibacterial property of Ag nanoparticle-impregnated N-doped titania films under visible light

NASA Astrophysics Data System (ADS)

Wong, Ming-Show; Chen, Chun-Wei; Hsieh, Chia-Chun; Hung, Shih-Che; Sun, Der-Shan; Chang, Hsin-Hou

2015-07-01

Photocatalysts produce free radicals upon receiving light energy; thus, they possess antibacterial properties. Silver (Ag) is an antibacterial material that disrupts bacterial physiology. Our previous study reported that the high antibacterial property of silver nanoparticles on the surfaces of visible light-responsive nitrogen-doped TiO2 photocatalysts [TiO2(N)] could be further enhanced by visible light illumination. However, the major limitation of this Ag-TiO2 composite material is its durability; the antibacterial property decreased markedly after repeated use. To overcome this limitation, we developed TiO2(N)/Ag/TiO2(N) sandwich films in which the silver is embedded between two TiO2(N) layers. Various characteristics, including silver and nitrogen amounts, were examined in the composite materials. Various analyses, including electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and ultraviolet-visible absorption spectrum and methylene blue degradation rate analyses, were performed. The antibacterial properties of the composite materials were investigated. Here we revealed that the antibacterial durability of these thin films is substantially improved in both the dark and visible light, by which bacteria, such as Escherichia coli, Streptococcus pyogenes, Staphylococcus aureus, and Acinetobacter baumannii, could be efficiently eliminated. This study demonstrated a feasible approach to improve the visible-light responsiveness and durability of antibacterial materials that contain silver nanoparticles impregnated in TiO2(N) films.

Exploring silver as a contrast agent for contrast-enhanced dual-energy X-ray breast imaging

PubMed Central

Tsourkas, A; Maidment, A D A

2014-01-01

Objective: Through prior monoenergetic modelling, we have identified silver as a potential alternative to iodine in dual-energy (DE) X-ray breast imaging. The purpose of this study was to compare the performance of silver and iodine contrast agents in a commercially available DE imaging system through a quantitative analysis of signal difference-to-noise ratio (SDNR). Methods: A polyenergetic simulation algorithm was developed to model the signal intensity and noise. The model identified the influence of various technique parameters on SDNR. The model was also used to identify the optimal imaging techniques for silver and iodine, so that the two contrast materials could be objectively compared. Results: The major influences on the SDNR were the low-energy dose fraction and breast thickness. An increase in the value of either of these parameters resulted in a decrease in SDNR. The SDNR for silver was on average 43% higher than that for iodine when imaged at their respective optimal conditions, and 40% higher when both were imaged at the optimal conditions for iodine. Conclusion: A silver contrast agent should provide benefit over iodine, even when translated to the clinic without modification of imaging system or protocol. If the system were slightly modified to reflect the lower k-edge of silver, the difference in SDNR between the two materials would be increased. Advances in knowledge: These data are the first to demonstrate the suitability of silver as a contrast material in a clinical contrast-enhanced DE image acquisition system. PMID:24998157

Chrysopogon zizanioides aqueous extract mediated synthesis, characterization of crystalline silver and gold nanoparticles for biomedical applications

PubMed Central

Arunachalam, Kantha D; Annamalai, Sathesh Kumar

2013-01-01

The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3) and chloroauric acid (HAuCl4) respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV)-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. PMID:23861583

Atomic oxygen degradation of Intelsat 4-type solar array interconnects: Laboratory investigations

NASA Technical Reports Server (NTRS)

Koontz, S. L.; Cross, J. B.; Hoffbauer, M. A.; Kirkendahl, T. D.

1991-01-01

A Hughes 506 type communication satellite belonging to the Intelsat organization was marooned in low Earth orbit on March 14, 1990, following failure of the Titan third stage to separate properly. The satellite, Intelsat VI, was designed for service in geosynchronous orbit and contains several material configurations which are susceptible to attack by atomic oxygen. Analysis showed the silver foil interconnects in the satellite photovoltaic array to be the key materials issue because the silver is exposed directly to the atomic oxygen ram flux. The results are reported of atomic oxygen degradation testing of Intelsat VI type silver foil interconnects both as virgin material and in a configured solar cell element. Test results indicate that more than 80 pct. of the original thickness of silver in the Intelsat VI solar array interconnects should remain after completion of the proposed Space Shuttle rescue and/or reboost mission.

Corrosion inhibiting composition for treating asbestos containing materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hartman, J.R.

A composition for transforming a chrysotile asbestos-containing material into a non-asbestos material is disclosed. The composition comprises water, at least about 30% by weight of an acid component, optionally a source of fluoride ions, and a corrosion inhibiting amount of thiourea, a lower alkylthiourea, a C{sub 8}{single_bond}C{sub 15} alkylpyridinium halide or mixtures. A method of transforming an asbestos-containing building material, while part of a building structure, into a non-asbestos material by using the present composition also is disclosed.

Corrosion inhibiting composition for treating asbestos containing materials

DOEpatents

Hartman, Judithann Ruth

1998-04-21

A composition for transforming a chrysotile asbestos-containing material into a non-asbestos material is disclosed, wherein the composition comprises water, at least about 30% by weight of an acid component, optionally a source of fluoride ions, and a corrosion inhibiting amount of thiourea, a lower alkylthiourea, a C.sub.8 -C.sub.15 alkylpyridinium halide or mixtures thereof. A method of transforming an asbestos-containing building material, while part of a building structure, into a non-asbestos material by using the present composition also is disclosed.

Corrosion inhibiting composition for treating asbestos containing materials

DOEpatents

Hartman, J.R.

1998-04-21

A composition for transforming a chrysotile asbestos-containing material into a non-asbestos material is disclosed. The composition comprises water, at least about 30% by weight of an acid component, optionally a source of fluoride ions, and a corrosion inhibiting amount of thiourea, a lower alkylthiourea, a C{sub 8}{single_bond}C{sub 15} alkylpyridinium halide or mixtures. A method of transforming an asbestos-containing building material, while part of a building structure, into a non-asbestos material by using the present composition also is disclosed.

Laser-triggered vacuum switch

DOEpatents

Brannon, Paul J.; Cowgill, Donald F.

1990-01-01

A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

Laser-triggered vacuum switch

DOEpatents

Brannon, P.J.; Cowgill, D.F.

1990-12-18

A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable. 10 figs.

Biomedical properties of laser prepared silver-doped hydroxyapatite

NASA Astrophysics Data System (ADS)

Jelínek, M.; Weiserová, M.; Kocourek, T.; Zezulová, M.; Strnad, J.

2011-07-01

Thin films of hydroxyapatite (HA) and silver-doped HA were synthesized using KrF excimer laser deposition. Material was ablated from one target composed from silver and HA segments. Layers properties as silver content, structure, color, FTIR spectra and antibacterial properties (Gram-positive Bacillus subtilis) were measured. Silver concentration in HA layers of 0.06, 0.3, 1.2, 4.4, 8.3, and 13.7 at % was detected. The antibacterial efficacy changed with silver dopation from 71.0 to 99.9%. The focus is on investigation of minimum Ag concentration needed to reach a high antibacterial efficacy.

Methods for producing single crystal mixed halide perovskites

DOEpatents

Zhu, Kai; Zhao, Yixin

2017-07-11

An aspect of the present invention is a method that includes contacting a metal halide and a first alkylammonium halide in a solvent to form a solution and maintaining the solution at a first temperature, resulting in the formation of at least one alkylammonium halide perovskite crystal, where the metal halide includes a first halogen and a metal, the first alkylammonium halide includes the first halogen, the at least one alkylammonium halide perovskite crystal includes the metal and the first halogen, and the first temperature is above about 21.degree. C.

Transport and retention of surfactant- and polymer-stabilized engineered silver nanoparticles in silicate-dominated aquifer material

USDA-ARS?s Scientific Manuscript database

Packed column experiments were conducted to investigate the transport and blocking behavior of surfactant- and polymer-stabilized engineered silver nanoparticles (Ag-ENPs) in saturated natural aquifer material with varying silt and clay content, background solution chemistry, and flow velocity. Brea...

Durable metallized polymer mirror

DOEpatents

Schissel, P.O.; Kennedy, C.E.; Jorgensen, G.J.; Shinton, Y.D.; Goggin, R.M.

1994-11-01

A metallized polymer mirror construction is disclosed having improved durability against delamination and tunneling, comprising: an outer layer of polymeric material; a metal oxide layer underlying the outer layer of polymeric material; a silver reflective layer underneath the metal oxide layer; and a layer of adhesive attaching the silver layer to a substrate. 6 figs.

Practical Microform Materials for Libraries: Silver, Diazo, Vesicular.

ERIC Educational Resources Information Center

Veaner, Allen B.

1982-01-01

Remarks on the relative permanence and durability of three types of film in use in library microform reproduction (silver, diazo, and vesicular) and points out some technical and economic facts that govern the choice of microform materials for libraries. A 6-item reference list is included. (Author/JL)

Green chemical synthesis of silver nanomaterials with maltodextrin.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tallant, David Robert; Lu, Ping; Lambert, Timothy N.

2010-11-01

Silver nanomaterials have significant application resulting from their optical properties related to surface enhanced Raman spectroscopy, high electrical conductivity, and anti-microbial impact. A 'green chemistry' synthetic approach for silver nanomaterials minimizes the environmental impact of silver synthesis, as well as lowers the toxicity of the reactive agents. Biopolymers have long been used for stabilization of silver nanomaterials during synthesis, and include gum Arabic, heparin, and common starch. Maltodextrin is a processed derivative of starch with lower molecular weight and an increase in the number of reactive reducing aldehyde groups, and serves as a suitable single reactant for the formation ofmore » metallic silver. Silver nanomaterials can be formed under either a thermal route at neutral pH in water or by reaction at room temperature under more alkaline conditions. Deposited silver materials are formed on substrates from near neutral pH solutions at low temperatures near 50 C. Experimental conditions based on material concentrations, pH and reaction time are investigated for development of deposited films. Deposit morphology and optical properties are characterized using SEM and UV-vis techniques. Silver nanoparticles are generated under alkaline conditions by a dissolution-reduction method from precipitated silver (II) oxide. Synthesis conditions were explored for the rapid development of stable silver nanoparticle dispersions. UV-vis absorption spectra, powder X-ray diffraction (PXRD), dynamic light scattering (DLS), and transmission electron microscopy (TEM) techniques were used to characterize the nanoparticle formation kinetics and the influence of reaction conditions. The adsorbed content of the maltodextrin was characterized using thermogravimetric analysis (TGA).« less

Precise micropatterning of silver nanoparticles on plastic substrates

NASA Astrophysics Data System (ADS)

Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A.

2017-04-01

Conventional fabrication methods to obtain metal patterns on polymer substrates are restricted by high operating temperature and complex preparation steps. The present study demonstrates a simple yet versatile method for preparation of silver nanoparticle micropatterns on polymer substrates with various surface geometry. With the microworking robot technique, we were able not only to directly structure the surface, but also precisely deposit silver nanoparticle ink on the desired surface location with the minimum usage of ink material. The prepared silver nanoparticle ink, containing silver cations and polyethylene glycol (PEG) as a reducing agent, yields silver nanoparticle micropatterns on plastic substrates at low sintering temperature without any contamination. The influence of the ink behaviour was studied, such as substrate wettability, ink volume, and sintering temperature. The ultraviolet visible (UV-vis), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements revealed the formation of micropatterns with uniformly distributed silver nanoparticles. The prepared patterns are expected to have a broad range of applications in optics, medicine, and sensor devices owing to the unique properties of silver. Furthermore, the deposition of a chemical compound, which is different from the substrate material, not only adds a fourth dimension to the prestructured three-dimensional (3D) surfaces, but also opens new application areas to the conventional surface structures.

Printed silver nanowire antennas with low signal loss at high-frequency radio.

PubMed

Komoda, Natsuki; Nogi, Masaya; Suganuma, Katsuaki; Kohno, Kazuo; Akiyama, Yutaka; Otsuka, Kanji

2012-05-21

Silver nanowires are printable and conductive, and are believed to be promising materials in the field of printed electronics. However, the resistivity of silver nanowire printed lines is higher than that of metallic particles or flakes even when sintered at high temperatures of 100-400 °C. Therefore, their applications have been limited to the replacement of transparent electrodes made from high-resistivity materials, such as doped metallic oxides, conductive polymers, carbon nanotubes, or graphenes. Here we report that using printed silver nanowire lines, signal losses obtained in the high-frequency radio were lower than those obtained using etched copper foil antennas, because their surfaces were much smoother than those of etched copper foil antennas. This was the case even though the resistivity of silver nanowire lines was 43-71 μΩ cm, which is much higher than that of etched copper foil (2 μΩ cm). When printed silver nanowire antennas were heated at 100 °C, they achieved signal losses that were much lower than those of silver paste antennas comprising microparticles, nanoparticles, and flakes. Furthermore, using a low temperature process, we succeeded in remotely controlling a commercialized radio-controlled car by transmitting a 2.45 GHz signal via a silver nanowire antenna printed on a polyethylene terephthalate film.

Silver Sodalites Novel Optically Responsive Nanocomposites

DTIC Science & Technology

1988-01-01

writing mechanim employed. The sodalite may be in the form of a self -suprting pressed disk, suspended in another material (e.g. glass or polymer), or...present study of silver sodalitas one can deduce that: i) silver sodalites can be synthesized with a variety of ptoraiac resposes ; ii) the distribution

On the Use of the Electrospinning Coating Technique to Produce Antimicrobial Polyhydroxyalkanoate Materials Containing In Situ-Stabilized Silver Nanoparticles.

PubMed

Castro-Mayorga, Jinneth Lorena; Fabra, Maria Jose; Cabedo, Luis; Lagaron, Jose Maria

2016-12-29

Electro-hydrodynamic processing, comprising electrospraying and electrospinning techniques, has emerged as a versatile technology to produce nanostructured fiber-based and particle-based materials. In this work, an antimicrobial active multilayer system comprising a commercial polyhydroxyalkanoate substrate (PHA) and an electrospun PHA coating containing in situ-stabilized silver nanoparticles (AgNPs) was successfully developed and characterized in terms of morphology, thermal, mechanical, and barrier properties. The obtained materials reduced the bacterial population of Salmonella enterica below the detection limits at very low silver loading of 0.002 ± 0.0005 wt %. As a result, this study provides an innovative route to generate fully renewable and biodegradable materials that could prevent microbial outbreaks in food packages and food contact surfaces.

On the Use of the Electrospinning Coating Technique to Produce Antimicrobial Polyhydroxyalkanoate Materials Containing In Situ-Stabilized Silver Nanoparticles

PubMed Central

Castro-Mayorga, Jinneth Lorena; Fabra, Maria Jose; Cabedo, Luis; Lagaron, Jose Maria

2016-01-01

Electro-hydrodynamic processing, comprising electrospraying and electrospinning techniques, has emerged as a versatile technology to produce nanostructured fiber-based and particle-based materials. In this work, an antimicrobial active multilayer system comprising a commercial polyhydroxyalkanoate substrate (PHA) and an electrospun PHA coating containing in situ-stabilized silver nanoparticles (AgNPs) was successfully developed and characterized in terms of morphology, thermal, mechanical, and barrier properties. The obtained materials reduced the bacterial population of Salmonella enterica below the detection limits at very low silver loading of 0.002 ± 0.0005 wt %. As a result, this study provides an innovative route to generate fully renewable and biodegradable materials that could prevent microbial outbreaks in food packages and food contact surfaces. PMID:28336838

Silver doped catalysts for treatment of exhaust

DOEpatents

Park, Paul Worn [Peoria, IL; Boyer, Carrie L [Shiloh, IL

2006-12-26

A method of making an exhaust treatment catalyst includes dispersing a metal-based material in a first solvent to form a first slurry and allowing polymerization of the first slurry to occur. Polymerization of the first slurry may be quenched and the first slurry may be allowed to harden into a solid. This solid may be redistributed in a second solvent to form a second slurry. The second slurry may be loaded with a silver-based material, and a silver-loaded powder may be formed from the second slurry.

Method for producing hydrocarbon fuels and fuel gas from heavy polynuclear hydrocarbons by the use of molten metal halide catalysts

DOEpatents

Gorin, Everett

1979-01-01

In a process for hydrocracking heavy polynuclear carbonaceous feedstocks to produce lighter hydrocarbon fuels by contacting the heavy feedstocks with hydrogen in the presence of a molten metal halide catalyst in a hydrocracking zone, thereafter separating at least a major portion of the lighter hydrocarbon fuels from the spent molten metal halide and thereafter regenerating the spent molten metal halide by incinerating the spent molten metal halide by combustion of carbon and sulfur compounds in the spent molten metal halide in an incineration zone, the improvement comprising: (a) contacting the heavy feedstocks and hydrogen in the presence of the molten metal halide in the hydrocracking zone at reaction conditions effective to convert from about 60 to about 90 weight percent of the feedstock to lighter hydrocarbon fuels; (b) separating at least a major portion of the lighter hydrocarbon fuels from the spent molten metal halide; (c) contacting the spent molten metal halide with oxygen in a liquid phase gasification zone at a temperature and pressure sufficient to vaporize from about 25 to about 75 weight percent of the spent metal halide, the oxygen being introduced in an amount sufficient to remove from about 60 to about 90 weight percent of the carbon contained in the spent molten metal halide to produce a fuel gas and regenerated metal halide; and (d) incinerating the spent molten metal halide by combusting carbon and sulfur compounds contained therein.

Low resistivity contacts to YBa2Cu3O(7-x) superconductors

NASA Technical Reports Server (NTRS)

Hsi, Chi-Shiung; Haertling, Gene H.

1991-01-01

Silver, gold, platinum, and palladium metals were investigated as electroding materials for the YBa2Cu3O(7-x) superconductors. Painting, embedding, and melting techniques were used to apply the electrodes. Contact resistivities were determined by: (1) type of electrode; (2) firing conditions; and (3) application method. Electrodes fired for long times exhibited lower contact resistivities than those fired for short times. Low-resistivity contacts were found for silver and gold electrodes. Silver, which made good ohmic contact to the YBa2Cu3O(7-x) superconductor with low contact resistivities was found to be the best electroding material among the materials evaluated in this investigation.

Reinforced silver-embedded silica matrix from the cheap silica source for the controlled release of silver ions

NASA Astrophysics Data System (ADS)

Hilonga, A.; Kim, J. K.; Sarawade, P. B.; Kim, H. T.

2009-07-01

In this study, a reinforced silver-embedded silica matrix was designed by utilizing the interaction between the [AlO 4] - tetrahedral and the Ag + in sol-gel process using sodium silicate as a silica precursor. The Ag + mole ratio in each sample was significantly varied to examine the influence of silver concentration on the properties of the final product. Aluminium ions were added to reinforce and improve the chemical durability of silver-embedded silica. A templated sample at Al/Ag = 1 atomic ratio was also synthesized to attempt a possibility of controlling porosity of the final product. Also, a sample neither embedded with silver nor templated was synthesized and characterized to serve as reference. The material at Al/Ag = 1 was found to have a desirable properties, compared to its counterparts, before and even after calcination up to 1000 °C. The results demonstrate that materials with desirable properties can be obtained by this unprecedented method while utilizing sodium silicate, which is relatively cheap, as a silica precursor. This may significantly boost the industrial production of the silver-embedded silicas for various applications.

Silver-free Metallization Technology for Producing High Efficiency, Industrial Silicon Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Michaelson, Lynne M.; Munoz, Krystal; Karas, Joseph

The goal of this project is to provide a commercially viable Ag-free metallization technology that will both reduce cost and increase efficiency of standard silicon solar cells. By removing silver from the front grid metallization and replacing it with lower cost nickel, copper, and tin metal, the front grid direct materials costs will decrease. This reduction in material costs should provide a path to meeting the Sunshot 2020 goal of 1 dollar / W DC. As of today, plated contacts are not widely implemented in large scale manufacturing. For organizations that wish to implement pilot scale manufacturing, only two equipmentmore » choices exist. These equipment manufacturers do not supply plating chemistry. The main goal of this project is to provide a chemistry and equipment solution to the industry that enables reliable manufacturing of plated contacts marked by passing reliability results and higher efficiencies than silver paste front grid contacts. To date, there have been several key findings that point to plated contacts performing equal to or better than the current state of the art silver paste contacts. Poor adhesion and reliability concerns are a few of the hurdles for plated contacts, specifically plated nickel directly on silicon. A key finding of the Phase 1 budget period is that the plated contacts have the same adhesion as the silver paste controls. This is a huge win for plated contacts. With very little optimization work, state of the art electrical results for plated contacts on laser ablated lines have been demonstrated with efficiencies up to 19.1% and fill factors ~80% on grid lines 40-50 um wide. The silver paste controls with similar line widths demonstrate similar electrical results. By optimizing the emitter and grid design for the plated contacts, it is expected that the electrical performance will exceed the silver paste controls. In addition, cells plated using Technic chemistry and equipment pass reliability testing; i.e. 1000 hours damp heat and 200 thermal cycles, with results similar to silver paste control cells. 100 cells have been processed through Technic’s novel demo plating tool built and installed during budget period 2. This plating tool performed consistently from cell to cell, providing gentle handling for the solar cells. An agreement has been signed with a cell manufacturer to process their cells through our plating chemistry and equipment. Their main focus for plated contacts is to reduce the direct materials cost by utilizing nickel, copper, and tin in place of silver paste. Based on current market conditions and cost model calculations, the overall savings offered by plated contacts is only 3.5% dollar/W versus silver paste contacts; however, the direct materials savings depend on the silver market. If silver prices increase, plated contacts may find a wider adoption in the solar industry in order to keep the direct materials costs down for front grid contacts.« less

Antibacterial and Antimycotic Activity of Cotton Fabrics, Impregnated with Silver and Binary Silver/Copper Nanoparticles

NASA Astrophysics Data System (ADS)

Eremenko, A. M.; Petrik, I. S.; Smirnova, N. P.; Rudenko, A. V.; Marikvas, Y. S.

2016-01-01

Effective method of obtaining of the bactericidal bandage materials by impregnation of cotton fabric by aqueous solutions of silver and copper salts followed by a certain regime of heat treatment is developed. The study of obtained materials by methods of optical spectroscopy, electron microscopy, and X-ray phase analysis showed the formation of crystalline silver nanoparticles (NPs) and bimetallic Ag/Cu composites with the corresponding surface plasmon resonance (SPR) bands in the absorption spectra. High antimicrobial and antimycotic properties of tissues with low concentrations of Ag and Ag/Cu nanoparticles (Ag/Cu NPs) (in the range 0.06-0.25 weight percent (wt%) for Ag and 0.015-0.13 wt% for Ag/Cu) is confirmed in experiments with a wide range of multidrug-resistant bacteria and fungi: Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, Candida albicans yeasts, and micromycetes . Textile materials with Ag NPs demonstrate high antibacterial activity, while fabrics doped with bimetallic composite Ag/Cu have pronounced antimycotic properties. Bactericidal and antifungal properties of the obtained materials do not change after a washing. Production of such materials is extremely fast, convenient, and cost-effective.

Changes in chroma of two indirect composite materials polymerized with different polymerization systems.

PubMed

Ayano, Michiya

2012-01-01

This study evaluated chroma change in two composite materials (Sinfony and Pearleste) polymerized with two different systems. Disk specimens were prepared using a metal halide unit (Hyper LII) and an exposure time of 60 to 180 s. The proprietary polymerization systems (Visio and Pearlcure systems) were used as the reference polymerization modes. After storage at 37°C for 24 h, CIE 1976 L*a*b* values were measured by using a dental chroma meter (ShadeEye NCC) with a gray background. The specimens were then immersed in water or tea. Color change from baseline to 4 weeks was evaluated by measuring ΔL*, Δa*, and Δb*, after which ΔE*(ab) values were calculated. The brightness of Sinfony specimens was reduced by tea immersion. The color of both materials shifted to yellow after tea immersion, although color change in Sinfony specimens was greater than that in Pearleste specimens. For both materials, color change was less after polymerization with the metal halide unit. In conclusion, Sinfony polymerized with the Hyper LII unit, and Pearleste polymerized with either system, were stable against discoloration due to tea immersion.

Intrinsic Instability of Cs2In(I)M(III)X6 (M = Bi, Sb; X = Halogen) Double Perovskites: A Combined Density Functional Theory and Experimental Study.

PubMed

Xiao, Zewen; Du, Ke-Zhao; Meng, Weiwei; Wang, Jianbo; Mitzi, David B; Yan, Yanfa

2017-05-03

Recently, there has been substantial interest in developing double-B-cation halide perovskites, which hold the potential to overcome the toxicity and instability issues inherent within emerging lead halide-based solar absorber materials. Among all double perovskites investigated, In(I)-based Cs 2 InBiCl 6 and Cs 2 InSbCl 6 have been proposed as promising thin-film photovoltaic absorber candidates, with computational examination predicting suitable materials properties, including direct bandgap and small effective masses for both electrons and holes. In this study, we report the intrinsic instability of Cs 2 In(I)M(III)X 6 (M = Bi, Sb; X = halogen) double perovskites by a combination of density functional theory and experimental study. Our results suggest that the In(I)-based double perovskites are unstable against oxidation into In(III)-based compounds. Further, the results show the need to consider reduction-oxidation (redox) chemistry when predicting stability of new prospective electronic materials, especially when less common oxidation states are involved.

A One-Dimensional Organic Lead Chloride Hybrid with Excitation-Dependent Broadband Emissions

DOE PAGES

Wu, Guanhong; Zhou, Chenkun; Ming, Wenmei; ...

2018-05-23

Organic–inorganic metal halide hybrids have emerged as a new class of materials with fascinating optical and electronic properties. The exceptional structure tunability has enabled the development of materials with various dimensionalities at the molecular level, from three-dimensional (3D) to 2D, 1D, and 0D. Here, we report a new 1D lead chloride hybrid, C 4N 2H 14PbCl 4, which exhibits unusual inverse excitation-dependent broadband emission from bluish-green to yellow. Density functional theory calculations were performed to better understand the mechanism of this excitation-dependent broadband emission. This 1D hybrid material is found to have two emission centers, corresponding to the self-trapped excitonsmore » (STEs) and vacancy-bound excitons. The excitation-dependent emission is due to different populations of these two types of excitons generated at different excitation wavelengths. Furthermore, this work shows the rich chemistry and physics of organic–inorganic metal halide hybrids and paves the way to achieving novel light emitters with excitation-dependent broadband emissions at room temperature.« less

Recovery of germanium-68 from irradiated targets

DOEpatents

Phillips, Dennis R.; Jamriska, Sr., David J.; Hamilton, Virginia T.

1993-01-01

A process for selective separation of germanium-68 from proton irradiated molybdenum targets is provided and includes dissolving the molybdenum target in a hydrogen peroxide solution to form a first ion-containing solution, contacting the first ion-containing solution with a cationic resin whereby ions selected from the group consisting of molybdenum, niobium, technetium, selenium, vanadium, arsenic, germanium, zirconium and rubidium remain in a second ion-containing solution while ions selected from the group consisting of rubidium, zinc, beryllium, cobalt, iron, manganese, chromium, strontium, yttrium and zirconium are selectively adsorbed by the first resin, adjusting the pH of the second ion-containing solution to within a range of from about 0.7 to about 3.0, adjusting the soluble metal halide concentration in the second ion-containing solution to a level adapted for subsequent separation of germanium, contacting the pH-adjusted, soluble metal halide-containing second ion-containing solution with a dextran-based material whereby germanium ions are separated by the dextran-based material, and recovering the germanium from the dextran-based material, preferably by distillation.

Apatite and sodalite based glass-bonded waste forms for immobilization of 129I and mixed halide radioactive wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goel, Ashutosh; McCloy, John S.; Riley, Brian J.

The goal of the project was to utilize the knowledge accumulated by the team, in working with minerals for chloride wastes and biological apatites, toward the development of advanced waste forms for immobilizing 129I and mixed-halide wastes. Based on our knowledge, experience, and thorough literature review, we had selected two minerals with different crystal structures and potential for high chemical durability, sodalite and CaP/PbV-apatite, to form the basis of this project. The focus of the proposed effort was towards: (i) low temperature synthesis of proposed minerals (iodine containing sodalite and apatite) leading to the development of monolithic waste forms, (ii)more » development of a fundamental understanding of the atomic-scale to meso-scale mechanisms of radionuclide incorporation in them, and (iii) understanding of the mechanism of their chemical corrosion, alteration mechanism, and rates. The proposed work was divided into four broad sections. deliverables. 1. Synthesis of materials 2. Materials structural and thermal characterization 3. Design of glass compositions and synthesis glass-bonded minerals, and 4. Chemical durability testing of materials.« less

Alloying n-Butylamine into CsPbBr3 to Give a Two-Dimensional Bilayered Perovskite Ferroelectric Material.

PubMed

Wu, Zhenyue; Ji, Chengmin; Li, Lina; Kong, Jintao; Sun, Zhihua; Zhao, Sangen; Wang, Sasa; Hong, Maochun; Luo, Junhua

2018-05-11

Cesium-lead halide perovskites (e.g. CsPbBr 3 ) have gained attention because of their rich physical properties, but their bulk ferroelectricity remains unexplored. Herein, by alloying flexible organic cations into the cubic CsPbBr 3 , we design the first cesium-based two-dimensional (2D) perovskite ferroelectric material with both inorganic alkali metal and organic cations, (C 4 H 9 NH 3 ) 2 CsPb 2 Br 7 (1). Strikingly, 1 shows a high Curie temperature (T c =412 K) above that of BaTiO 3 (ca. 393 K) and notable spontaneous polarization (ca. 4.2 μC cm -2 ), triggered by not only the ordering of organic cations but also atomic displacement of inorganic Cs + ions. To our knowledge, such a 2D bilayered Cs + -based metal-halide perovskite ferroelectric material with inorganic and organic cations is unprecedented. 1 also shows photoelectric semiconducting behavior with large "on/off" ratios of photoconductivity (>10 3 ). © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manser, Joseph S.; Christians, Jeffrey A.; Kamat, Prashant V.

Here, a new chapter in the long and distinguished history of perovskites is being written with the breakthrough success of metal halide perovskites (MHPs) as solution-processed photovoltaic (PV) absorbers. The current surge in MHP research has largely arisen out of their rapid progress in PV devices; however, these materials are potentially suitable for a diverse array of optoelectronic applications. Like oxide perovskites, MHPs have ABX 3 stoichiometry, where A and B are cations and X is a halide anion. Here, the underlying physical and photophysical properties of inorganic (A = inorganic) and hybrid organic-inorganic (A = organic) MHPs are reviewedmore » with an eye toward their potential application in emerging optoelectronic technologies. Significant attention is given to the prototypical compound methylammonium lead iodide (CH 3NH 3PbI 3) due to the preponderance of experimental and theoretical studies surrounding this material. We also discuss other salient MHP systems, including 2- dimensional compounds, where relevant. More specifically, this review is a critical account of the interrelation between MHP electronic structure, absorption, emission, carrier dynamics and transport, and other relevant photophysical processes that have propelled these materials to the forefront of modern optoelectronics research.« less