scholarly journals Enhanced Photoluminescence of Electrodeposited Europium Complex on Bare and Terpyridine-Functionalized Porous Si Surfaces

Photochem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 38-52
Author(s):  
Min Hee Joo ◽  
So Jeong Park ◽  
Hye Ji Jang ◽  
Sung-Min Hong ◽  
Choong Kyun Rhee ◽  
...  

The trivalent Eu(III) ion exhibits unique red luminescence and plays an significant role in the display industry. Herein, the amperometry electrodeposition method was employed to electrodeposit Eu(III) materials on porous Si and terpyridine-functionalized Si surfaces. The electrodeposited materials were fully characterized by scanning electron microscopy, X-ray diffraction crystallography, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Photoluminescence (PL) spectroscopy revealed that PL signals were substantially increased upon deposition on porous Si surfaces. PL signals were mainly due to direct excitation and charge-transfer-indirect excitations before and after thermal annealing, respectively. The as-electrodeposited materials were of a Eu(III) complex consisting of OH, H2O, NO3−, and CO32− groups. The complex was transformed to Eu2O3 upon thermal annealing at 700 °C. The electrodeposition on porous surfaces provide invaluable information on the fabrication of thin films for displays, as well as photoelectrodes for catalyst applications.

CORROSION ◽  
10.5006/3881 ◽  
2021 ◽  
Author(s):  
Zachary Karmiol ◽  
Dev Chidambaram

This work investigates the oxidation of a nickel based superalloy, namely Alloy X, in water at elevated temperatures: subcritical water at 261°C and 27 MPa, the transition between subcritical and supercritical water at 374°C and 27 MPa, and supercritical water at 380°C and 27 MPa for 100 hours. The morphology of the sample surfaces were studied using scanning electron microscopy coupled with focused ion beam milling, and the surface chemistry was investigated using X-ray diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy before and after exposure studies. Surfaces of all samples were identified to comprise of a ferrite spinel containing aluminum.


2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.


Clay Minerals ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Y. F. Cai ◽  
J. Y. Xue

AbstractDesorption experiments performed on four Cu-adsorbed palygorskites suggest that the leached Cu2+ ion originates at the surface and/or net-like interstice of the palygorskite fibres. The leached fraction, calculated from the quantities of adsorbed Cu2+ before and after desorption, is <1%. This may indicate that the majority of Cu is in inaccessible structural sites. X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared (FTIR) spectroscopy and electron spin resonance (ESR) were used to determine the mineralogical character of the Cu-adsorbed palygorskite. Two photoelectron lines at 932.5 and/or 933.7 eV in the narrow scan Cu 2p3/2 spectra show that Cu adsorbed on the surface of palygorskite is in the Cu+ and Cu2+ state. The stretching vibrations of the octahedral cation shift ~3–5 cm–1 towards a greater wavenumber in the FTIR spectra of Cu-adsorbed palygorskite. It can be deduced that the Cu2+ is trapped in the channel of the palygorskite structure. The ESR spectra of the palygorskite give g values of 2.34, 2.12, 2.08 and 2.05, suggesting that some Cu ions cannot be reached by H+. These results confirm that Cu is adsorbed by palygorskite via three possible mechanisms: (1) the Cu is adsorbed onto the surface or in a net-like interstice, and its oxidation states are +1 and +2; (2) Cu forms a complex ion – [Cu(H2O)4]2+ or [Cu(H2O)6]2+, and is trapped in the channel; or (3) Cu enters into the hexagonal channel of the tetrahedral sites or the unoccupied octahedral sites of palygorskite.


Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2253 ◽  
Author(s):  
Magdalena Tuchowska ◽  
Barbara Muir ◽  
Mariola Kowalik ◽  
Robert P. Socha ◽  
Tomasz Bajda

Montmorillonite—the most popular mineral of the smectite group—has been recognized as a low-cost, easily available mineral sorbent of heavy metals and other organic and inorganic compounds that pollute water. The aim of this work was to determine the sorption mechanism and to identify the reaction products formed on the surface of montmorillonite and organo-montmorillonite after sorption of molybdates (Mo(VI)) and tungstates (W(VI)). Montmorillonites are often modified to generate a negative charge on the surface. The main objective of the study was to investigate and compare the features of Na-montmorillonite (Na-M), montmorillonite modified with dodecyl trimethyl ammonium bromide (DDTMA-M), and montmorillonite modified with didodecyl dimethyl ammonium bromide (DDDDMA-M) before and after sorption experiments. The material obtained after sorption was studied by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The XRD pattern showed the presence of a new crystallic phase in the sample that was observed under an SEM as an accumulation of crystals. The FTIR spectra showed bands related to Mo–O and W–O vibration (840 and 940 cm−1, respectively). The obtained results suggest that molybdenum(VI) and tungsten(VI) ions sorb onto the organo-montmorillonite in the form of alkylammonium molybdates and tungstates.


2007 ◽  
Vol 14 (04) ◽  
pp. 535-538 ◽  
Author(s):  
J. S. BAE ◽  
J. H. YOON ◽  
S. K. PARK ◽  
J. P. KIM ◽  
E. D. JEONG ◽  
...  

Influence of lithium doping on the crystallization, the surface morphology, the chemical states and the luminescent properties of Y 2 O 3: Eu 3+ phosphors was investigated. The structural, surface morphology characteristics and chemical states of the phosphors were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. The crystallinity, the surface morphology, and the cathodoluminescence (CL) of phosphors highly depended on the Li doping. The relationship between the crystalline and morphological structures and the luminescent properties was studied, and Li + doping affected not only the crystallinity but also the luminescent brightness of Y 2 O 3: Eu 3+ phosphors. In particular, the incorporation of the Li + ion into the Y 2 O 3 lattice could induce remarkable increase in the CL intensity. The enhanced photoluminescence brightness with Li doping may result both from the improved crystallinity leading to higher oscillating strengths for the optical transitions, and the increased surface area due to the larger particle sizes. The strongest emission intensity was observed with Li doped Y 2 O 3: Eu 3+ ceramics whose brightness was increased by a factor of 1.8 in comparison with that of Y 2 O 3: Eu 3+ ceramics.


2009 ◽  
Vol 24 (8) ◽  
pp. 2720-2727 ◽  
Author(s):  
Xuebin Yu ◽  
Guanglin Xia ◽  
Zaiping Guo ◽  
Huakun Liu

LiBH4/Al mixtures with various mol ratios were prepared by ball milling. The hydrogen storage properties of the mixtures were evaluated by differential scanning calorimetry/thermogravimetry analyses coupled with mass spectrometry measurements. The phase compositions and chemical state of elements for the LiBH4/Al mixtures before and after hydrogen desorption and absorption reactions were assessed via powder x-ray diffraction, infrared spectroscopy, and x-ray photoelectron spectroscopy. Dehydrogenation results revealed that LiBH4 could react with Al to form AlB2 and AlLi compounds with a two-step decomposition, resulting in improved dehydrogenation. The rehydrogenation experiments were investigated at 600 °C with various H2 pressure. It was found that intermediate hydride was formed firstly at a low H2 pressure of 30 atm, while LiBH4 could be reformed completely after increasing the pressure to 100 atm. Absorption/desorption cycle results showed that the dehydrogenation temperature increased and the hydrogen capacity degraded with the increase of cycle numbers.


Coatings ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 431
Author(s):  
Bohan Zhang ◽  
Kaili Xu ◽  
Xin Zheng ◽  
Xiwen Yao ◽  
Yantong Wang ◽  
...  

Hydrogen, which can be produced due to the accumulation of aluminum dust that reacts with water in wet dust removal systems, is a fire and explosion hazard. To reduce hydrogen production, sodium tungstate is used in hydrogen inhibition experiments to inhibit the reaction between aluminum dust and water. The purity of the aluminum powder was 95.15%, analyzed with X-ray fluorescence spectrometry (XRF). Each of the hydrogen inhibition experiments lasted for 12 h. In addition, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface morphology and composition of particles before and after the experiments. There was nearly no hydrogen produced when the concentration of the sodium tungstate solution reached 100 g/L. The results show that a protective coating containing W element was formed on the surface of the aluminum particles after the reaction with sodium tungstate, and the coating prevented the aluminum particles from contacting with water.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shekhar Bhatia ◽  
Venkatesh Nagendrababu ◽  
Ove A. Peters ◽  
Amr Fawzy ◽  
Umer Daood

AbstractTo evaluate structural profiles and mechanical behaviour of WaveOne Gold (WOG), Twisted File Adaptive (TFA) and XP-endo shaper (XPS) instruments after root canal preparation. Standardized in vitro shaping was performed in presence of 5.25% sodium hypochlorite. File morphology was analyzed using scanning electron microscopy; X-ray diffraction analysis was performed before and after use along with Raman spectroscopy. Nanoindentation was carried out to characterize surface topography. Ni2+ release was measured at 1, 3, 5 and 7 days. X-ray photoelectron spectroscopy (XPS) analysis was done before and after use. After allocating scan line shifts like in WOG, mechanical deformation was shown using first order polynomials. XPS file system showed minimal grooves on surface. SEM of WOG instrument showed scraping surface defects. Hardness varied from 8.11 ± 0.99 GPa in TFA system to 6.7 ± 1.27 GPa and 4.06 ± 4.1 GPa in XPS and WOG. Ni2+ concentration from WOG was 171.2 μg/L. Raman peak at 540–545 cm−1 is attributed to Cr2O3. High resolution of Ti 2p spectrum show distinctive peaks with binding energies dominating in WOG, XPS and TFA file system. XRD exhibited NiTi phases with diffraction peaks. WOG files showed more surface deterioration and less passive layer formation as compared to TFA and XPS systems.


Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 461 ◽  
Author(s):  
Runlin Han ◽  
Min Chen ◽  
Xiaobing Liu ◽  
Yuhang Zhang ◽  
Yongli Xie ◽  
...  

Nanosized Mn3O4 nanowires are prepared with KMnO4 and ethanol in mild conditions by facile hydrothermal method. Hydrothermal reaction temperature is optimized to get uniform nanowires. The prepared Mn3O4 nanowires exhibit high activity in the treatment of phenol at acid condition and room temperature. The 20 mg Mn3O4 nanowires can efficiently dispose of 50 mL phenol solution (0.2 g·L−1) at pH 2 and 25 °C. The nanowires before and after phenol treatment are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) and the reaction mechanism is discussed.


1994 ◽  
Vol 365 ◽  
Author(s):  
N.R. Khasgiwale ◽  
E.P. Butler ◽  
L. Tsakalakos ◽  
D.A. Hensley ◽  
W.R. Cannon ◽  
...  

ABSTRACTPseudo-porous SiC/C coatings were deposited on Nextel™440 and Nicalon™ fibers by CVD. The morphology and chemistry of the coatings was evaluated, both before and after oxidation, using Scanning Electron Microscopy (SEM), X-Ray Diffraction Analysis (XRD), X-Ray Photoelectron Spectroscopy (XPS) and Auger spectroscopy. Coated fibers were subjected to two different oxidation treatments to assess coating stability: a) oxidation at 600°C for 20 hours, and b) oxidation at 1000°C for 20 hours. Pseudo-porous SiC/C on Nicalon™ fibers appear to be more oxidation resistant than the same coatings on Nextel™440 fibers.


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