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Raman crystallinity

Neena Prasad, Karthikeyan Balasubramanian
We report, the enhanced photocatalytic behaviour of Cu doped ZnS micro crystals. ZnS and different concentrations of Cu doped ZnS microcrystals were prepared. X-ray diffraction confirms the crystalline and phase of the particles. Morphology and sizes were studied using Scanning Electron Microscopy (SEM). Recorded optical absorption spectra show a band for around 365nm for pure ZnS, but there is a broad band in the near infrared regime for the Cu-doped ZnS microcrystals which are attributed to the d-d transitions of Cu(2+) ions...
October 17, 2016: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Hafeez Ullah, Ibrahim Khan, Zain H Yamani, Ahsanulhaq Qurashi
Synthesis of SnO2 nanoparticles have been successfully accomplished moderately at lower temperature by facile, rapid, efficient and mild ultrasonic irradiation method. The as-grown SnO2 nanoparticles are investigated by various characterization techniques in terms of structural, optical, electrical and gas sensing properties. XRD investigation has shown that the SnO2 nanoparticles materials exhibit single rutile crystal phase with high crystallinity. FESEM studies showed uniform and monodisperse morphology of SnO2 nanoparticles...
January 2017: Ultrasonics Sonochemistry
Jianli Zou, Christopher Sole, Nicholas E Drewett, Matej Velicky, Laurence J Hardwick
An in situ Raman spectroelectrochemical study of Li intercalation into graphite flakes with different thicknesses ranging from 1.7 nm (3 graphene layers) to 61 nm (ca. 178 layers) is presented. The lithiation behavior of these flakes was compared to commercial microcrystalline graphite with a typical flake thickness of ca. 100 nm. Li intercalation into the graphitic flakes was observed under potential control via in situ optical microscopy and Raman spectroscopy. As graphite flakes decreased in thickness, a Raman response indicative of increased tensile strain along the graphene sheet was observed during the early stages of intercalation...
October 14, 2016: Journal of Physical Chemistry Letters
Zhuoran Wang, Samir Elouatik, George P Demopoulos
Kesterite, a highly promising photo-absorbing crystalline form of Cu2ZnSnS4 (CZTS), has been prepared via various routes. However, the lack of in-depth understanding of the dynamic phase formation process of kesterite leads to difficulties in optimizing its annealing conditions, hence its light harvesting performance. In this paper, in situ Raman monitored-annealing is applied to study the phase formation kinetics of nano-crystalline kesterite from a precursor deposited on a TiO2 mesoscopic scaffold. By performing in situ Raman annealing under different experimental conditions and wavelengths, several facts have been discovered: kesterite crystallization starts at as low as 170 °C, but after short time annealing at 300 °C followed by cooling, the initially formed kesterite is found to decompose...
October 14, 2016: Physical Chemistry Chemical Physics: PCCP
Ying Gao, Mojtaba Asadirad, Yao Yao, Pavel Dutta, Eduard Galstyan, Shahab Shervin, Keon-Hwa Lee, Sara Pouladi, Sicong Sun, Yongkuan Li, Monika Rathi, Jae-Hyun Ryou, Venkat Selvamanickam
Single-crystal-like semiconductor thin films on flexible inexpensive substrates by direct deposition are a promising candidate for high-performance and low-cost devices of flexible electronics. However, device operation of the transistors has been challenging. We report the demonstration of high-performance flexible thin-film transistors (TFTs) using single-crystal-like Si thin film with on/off ratio of ~10(6), a field-effect mobility of ~200 cm(2)/V-s, and saturation current levels of I/LW >50 μA/µm, which are significantly higher than performance characteristics of other state-of-the-art flexible TFTs based on amorphous, organic, and oxide semiconductors...
October 13, 2016: ACS Applied Materials & Interfaces
Yoshito Hamada, Makoto Ono, Motomu Ohara, Etsuo Yonemochi
In this study, the effect of structurally related impurities on crystallinity reduction of sulfamethazine by grinding was evaluated. The crystallinity of sulfamethazine was not decreased when it was ground alone. However, when structurally related impurities with sulfonamide derivatives were blended, the crystallinity of sulfamethazine was decreased by grinding. Other materials without a sulfonamide moiety showed no such effect. The Raman spectra of sulfamethazine demonstrated that there was a difference between its crystalline and amorphous states within its sulfonamide structure...
October 5, 2016: International Journal of Pharmaceutics
Yu Liu, Lianlian Chen, Donovan Hilliard, Qing-Song Huang, Fang Liu, Mao Wang, Roman Böttger, René Hübner, Alpha T N'Diaye, Elke Arenholz, Viton Heera, Wolfgang Skorupa, Shengqiang Zhou
We investigated how to control the growth of vertically aligned graphene on C-face SiC by varying the processing conditions. It is found that, the growth rate scales with the annealing temperature and the graphene height is proportional to the annealing time. Temperature gradient and crystalline quality of the SiC substrates influence their vaporization. The partial vapor pressure is crucial as it can interfere with further vaporization. A growth mechanism is proposed in terms of physical vapor transport. The monolayer character of vertically aligned graphene is verified by Raman and X-ray absorption spectroscopy...
October 6, 2016: Scientific Reports
Jiangping Yin, Tongqi Yuan, Yun Lu, Kunlin Song, Hanyin Li, Guangjie Zhao, Yafang Yin
The changes of porosity, chemical composition and cellulose crystalline structure of Spruce (Picea abies Karst.) wood cell walls due to compression combined with steam treatment (CS-treatment) were investigated by nitrogen adsorption, confocal Raman microscopy (CRM) and X-ray diffraction (XRD), respectively. A number of slit-shaped mesopores with a diameter of 3.7nm was formed for the CS-treated wood, and more mesopores were found in the steam-treated wood. CRM results revealed cellulose structure was affected by treatment and β-aryl-ether links associated to guaiacyl units of lignin was depolymerized followed by re-condensation reactions...
January 2, 2017: Carbohydrate Polymers
Vincent Consonni, Laetitia Rapenne, Gilles Renou, Hervé Roussel, Lionel Gérard, Ramón Cuscó, Lluís Artús, Régis André, Edgar F Rauch
Identifying and mapping the crystalline phases and orientation relationships on the local scale in core-shell ZnO nanowire heterostructures are of primary importance to improve the interface quality, which governs the performances of the nanoscale devices. However, this represents a major difficulty, especially when the expected polytypes exhibit very similar properties as in the case of CdSe. In the present work, we address that issue in ZnO nanowire heterostructures involving a uniform and highly conformal CdSe shell grown by molecular beam epitaxy...
September 30, 2016: Nanotechnology
Clément Brandel, Yohann Cartigny, Gérard Coquerel, Joop H Ter Horst, Samuel Petit
The crystallisation behaviour of (RS)-diprophylline (DPL) in two different solvents is investigated to assess the incidence of solvated pre-associations on nucleation, crystal growth and chiral discrimination. In the solvated state, Raman spectroscopy shows that dimeric associations similar to those depicted in the crystalline solid solution (ssRII) predominate in isopropanol (IPA), which may account for the systematic spontaneous nucleation of this crystal form from this solvent. By contrast, spontaneous nucleation in DMF yields the stable racemic compound RI, consistently with the distinct features of the Raman spectrum collected in this solvent...
November 2, 2016: Chemistry: a European Journal
H Kamimura, R C Gouveia, S C Carrocine, L D Souza, A D Rodrigues, M D Teodoro, G E Marques, E R Leite, A J Chiquito
Indium phosphide nanowires with a single crystalline zinc-blend core and polycrystalline/amorphous shell were grown from a reliable route without the use of hazardous precursors. The nanowires are composed by a crystalline core covered by a polycrystalline shell, presenting typical lengths larger than 10 μm and diameters of 80-90 nm. Raman spectra taken from as-grown nanowires exhibited asymmetric line shapes with broadening towards higher wave numbers which can be attributed to phonon localization effects...
November 30, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Xiaohong Bi, Ingo Grafe, Hao Ding, Rene Flores, Elda Munivez, Ming Ming Jiang, Brian Dawson, Brendan Lee, Catherine G Ambrose
Osteogenesis Imperfecta (OI) is a group of genetic disorders characterized by brittle bones that are prone to fracture. While previous studies in animal models investigated the mechanical properties and material composition of OI bone, little work has been conducted to statistically correlate these parameters to identify key compositional contributors to the impaired bone mechanical behaviors in OI. Further, while increased TGF-β signaling has been demonstrated as a contributing mechanism to the bone pathology in OI models, the relationship between mechanical properties and bone composition after anti-TGF-β treatment in OI has not been studied...
September 20, 2016: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
Soumen Mandal, Evan L H Thomas, Titus A Jenny, Oliver A Williams
With the large differences in surface energy between film and substrate in combination with the low sticking coefficient of hydrocarbon radicals, nanocrystalline diamond growth on foreign substrates typically results in poor nucleation densities. A seeding technique is therefore required to realize pinhole-free and thin coalesced films. In this work, a chemical nucleation method for growth of diamond on nondiamond substrates based on 2,2-divinyladamantane is shown. After treating with the carbon-containing DVA, the chemically treated wafers were exposed to low-power-density plasma, known as the incubation phase, to facilitate the formation of diamond nucleation sites followed by a high-power-density growth regime to produce coalesced films...
October 5, 2016: ACS Applied Materials & Interfaces
Takatsugu Endo, Shinpei Hoshino, Yuichi Shimizu, Kozo Fujii, Keiko Nishikawa
The flexibility and conformational variety of the butyl group in cations of ionic liquids (ILs) play an important role in dictating the macroscopic and microscopic properties of ILs. Here we calculate potential energy surfaces for the dihedral angles of the butyl group in four different types of cyclic cations, imidazolium, pyridinium, pyrrolidinium, and piperidinium, using the density functional theory method. The calculation results highlight the role of the butyl group in these cations by comparison of five-membered and six-membered rings, and of aromatic and alicyclic rings, in terms of stable conformations and rotational barriers...
October 6, 2016: Journal of Physical Chemistry. B
Renu Geetha Bai, Kasturi Muthoosamy, Meifang Zhou, Muthupandian Ashokkumar, Nay Ming Huang, Sivakumar Manickam
In this study, a sonochemical approach was utilised for the development of graphene-gold (G-Au) nanocomposite. Through the sonochemical method, simultaneous exfoliation of graphite and the reduction of gold chloride occurs to produce highly crystalline G-Au nanocomposite. The in situ growth of gold nanoparticles (AuNPs) took place on the surface of exfoliated few-layer graphene sheets. The G-Au nanocomposite was characterised by UV-vis, XRD, FTIR, TEM, XPS and Raman spectroscopy techniques. This G-Au nanocomposite was used to modify glassy carbon electrode (GCE) to fabricate an electrochemical sensor for the selective detection of nitric oxide (NO), a critical cancer biomarker...
September 1, 2016: Biosensors & Bioelectronics
A Bannerman, R L Williams, S C Cox, L M Grover
The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco's - Minimum Essential Medium (with and without serum)...
2016: Scientific Reports
In Soo Kim, Richard T Haasch, Duyen H Cao, Omar K Farha, Joseph T Hupp, Mercouri G Kanatzidis, Alex B F Martinson
A low-temperature (<120 °C) route to pinhole-free amorphous TiO2 compact layers may pave the way to more efficient, flexible, and stable inverted perovskite halide device designs. Toward this end, we utilize low-temperature thermal atomic layer deposition (ALD) to synthesize ultrathin (12 nm) compact TiO2 underlayers for planar halide perovskite PV. Although device performance with as-deposited TiO2 films is poor, we identify room-temperature UV-O3 treatment as a route to device efficiency comparable to crystalline TiO2 thin films synthesized by higher temperature methods...
September 21, 2016: ACS Applied Materials & Interfaces
Pengtao Sheng, Weili Li, Pengwei Du, Kesheng Cao, Qingyun Cai
Vertically aligned single crystalline CuO nanowire arrays (NWs) grown directly on TiO2 nanotube arrays (NTAs) supporting by Ti foil have been successfully fabricated using facile thermal oxidation of Cu nanocrystals in static air. CuO NWs growth behavior dependent on parent Cu nanocrystals sizes has been well investigated. Mass transport channel of Cu ions in horizontal and vertical for supporting CuO NWs diameter and length changes has been confirmed through a novel step-by-step surface diffusion process. CuO NWs, nano-mushrooms and nanosheets can be easily obtained by varying growth conditions...
November 1, 2016: Talanta
Yutaka Okazaki, Thierry Buffeteau, Elise Siurdyban, David Talaga, Naoya Ryu, Ryohei Yagi, Emilie Pouget, Makoto Takafuji, Hirotaka Ihara, Reiko Oda
Synthesis of chiral inorganic or hybrid nanomaterials through sol-gel transcription of chiral organic templates has attracted a great deal of interest for more than a decade. However, the chiral nature of these inorganic matrices has never been directly observed. For the first time, we report a direct evaluation of chirality on noncrystalline silica chiral nanoribbons by vibrational circular dichroism (VCD) measurements. Strong Cotton effect around 1150-1000 cm(-1) from Si-O-Si asymmetric stretching vibration was observed...
October 12, 2016: Nano Letters
Özlem Özgenç, Sefa Durmaz, Ismail Hakki Boyaci, Haslet Eksi-Kocak
In this study, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and Fourier-transform Raman (FT-Raman) spectroscopy techniques were used to determine changes in the chemical structure of heat-treated woods. For this purpose, scots pine (Pinus sylvestris L.), oriental beech (Fagus orientalis L.), and oriental spruce (Picea orientalis L.) wood species were heat-treated at different temperatures. The effect of chemical changes on the FT-Raman and ATR-FTIR bands or ratios of heat-treated wood was related with the OH association of cellulose, functional groups, and the aromatic system of lignin...
January 15, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
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