Search results for "Neodymium"
showing 10 items of 84 documents
CCDC 801153: Experimental Crystal Structure Determination
2011
Related Article: A.Jana, S.Majumder, L.Carrella, M.Nayak, T.Weyhermueller, S.Dutta, D.Schollmeyer, E.Rentschler, R.Koner, S.Mohanta|2010|Inorg.Chem.|49|9012|doi:10.1021/ic101445n
Evolution of the neodymium isotopic signature of neritic seawater on a northwestern Pacific margin: new constrains on possible end-members for the co…
2013
11 pages; International audience; The Neodymium(Nd) isotope composition of fish remains has beenwidely used to track past changes in oceanic circulation. Although the number of published Nd isotope data for the Cretaceous has markedly increased in the last years, no consensus has been reached on the structure of the oceanic circulation and its evolution during the Late Cretaceous. Yet this period is characterised bymajor geodynamical and climatic changes andmarked by the disappearance of global oceanic anoxic events inwhich changes in oceanic circulation modesmay have played a significant role. In this study we present the first record of Nd isotopic composition of fish remains from contine…
Rare earth element and neodymium isotope tracing of sedimentary rock weathering
2020
Chemical weathering plays an important role in sequestering atmospheric CO2, but its potential influence on global climate over geological timescales remains debated. To some extent, this uncertainty arises from the difficulty in separating the respective contribution of sedimentary and crystalline silicate rocks to past weathering rates in the geological record; two types of rocks having presumably different impact on the long-term carbon cycle. In this study, we investigate the use of rare earth element (REE) and neodymium isotopes (εNd) in leached iron oxide fractions of river sediments for tracing the origin of weathered rocks on continents. A new index, called ‘concavity index’ (CI), i…
Water mass exchange and variations in seawater temperature in the NW Tethys during the Early Jurassic: evidence from neodymium and oxygen isotopes of…
2009
10 pages; International audience; Oxygen and neodymium isotope analyses performed on biostratigraphically well-dated fish remains recovered from the Hettangian to Toarcian of the Paris Basin were used to reconstruct variations of Early Jurassic seawater temperature and to track oceanographic changes in the NW Tethys. Our results indicate a strong correlation between δ18O trends recorded by fish remains and belemnites, confirming the paleoenvironmental origin of oxygen isotope variations. Interestingly, temperatures recorded by pelagic fishes and nektobenthic belemnites and bottom dwelling fishes are comparable during the Late Pliensbachian sea-level lowstand but gradually differ during the …
Spectroscopic and physicochemical properties of rare-earth phthalocyanines entrapped in sol-gel glasses
1997
Abstract The electronic absorption spectra of samarium and neodymium phthalocyanines in DMSO and entrapped in glasses obtained via the sol-gel technique have been obtained. Decrease in concentration of metallophtalocyanines in DMSO leads to observed changes in the relative intensifies of the two bands in the Q-band region. This behavior could be explained by the shifts in equilibrium between the LnPc 2 and LnPc + forms, caused by the dilution. In view of this interpretation, the entrapment of the metallophthalocyanines in the sol-gel glass matrices shifts the diphthalocyanine ⇆ monophthalocyanine equilibrium towards the monophthalocyanine (LnPc + ) form.
Endovenous treatment of the great saphenous vein using a 1,320 nm Nd:YAG laser causes fewer side effects than using a 940 nm diode laser.
2005
Limited data are available about treatment-related side effects with respect to laser wavelength in endovenous laser treatment (ELT) of the great saphenous vein (GSV).To compare the results and side effects of a 940 nm diode and a 1,320 nm neodymium:yttium-aluminum-garnet (Nd:YAG) laser.Three patient cohorts (A, B, and C) received ELT of the GSV using a 940 nm diode laser at 15 W (group A) or 30 W (group B) or using a 1,320 nm laser at 8 W (group C). In all cases, energy was administered continuously with constant pullback of the laser fiber under perivenous tumescent local anesthesia.The GSVs of group A (n = 113), group B (n = 136), and group C (n = 33) received ELT. An average linear endo…
Co-precipitation synthesis of Nd:YAG nano-powders: the effect of Nd dopant addition with thermal treatment
2007
Nanopowders of Yttrium Aluminium Garnet doped with neodymium ions were obtained by the co-precipitation method from the reaction of aluminium, yttrium and neodymium nitrate with ammonia. The amount of neodymium was selected in order to produce samples of nominal stoichiometry NdXY (3-X)Al5O12 (where X = 0.006, 0.012, 0.024, 0.048, 0.081, 0.096, 0.17, 0.19, 0.38, 0.54, and 0.72, respectively). After washing and drying, the hydroxide precursors were subjected to Thermo-Gravimetry and Differential Thermal Analysis experiments from room temperature up to 1500 °C, which showed the presence of exothermal events accompanying phase transformation phenomena. X-ray diffraction investigations conducte…
Coprecipitation synthesis of Nd:YAG nanopowders II: the effect of Nd dopant addition the on Luminescence Properties
2009
Abstract Nanopowders of Yttrium Aluminium Garnet (Y3Al5O12, YAG) doped with neodymium (Nd:YAG, 0.2–24.0 at.%) were prepared using the co-precipitation method followed by an annealing treatment up to 950 °C. For a concentration of neodymium lower than 3.2 at.% the materials were found constituted by the garnet phase according to X-ray diffraction investigations. However, at higher neodymium loading the hexagonal and monoclinic forms of yttrium aluminium oxides were found together with the garnet phase. For Nd quantity lower than 0.8% the luminescence emission spectra appear to be nearly the same, indicating that in the examined range of composition the immediate surrounding of the emitting N…
Dinuclear chloroneodymium quinolinylcarboxylates: The molecular structures affected by water and the catalytic behavior toward isoprene polymerization
2016
Abstract A series of dinuclear chloroneodymium quinolinylcarboxylate compounds was synthesized and characterized. The nature and importance of metal-organic aggregations have been considered as an important factor regarding the molecular structure and catalytic performance. The neodymium center in all the title compounds exhibits the coordination numbers of 8. Cage aggregation was observed in the solid state, and the cyclic arrangement was achieved when water molecules were incorporated into the structure. Upon the activation with Al(i-Bu)3, all the title neodymium compounds form the efficient catalysts for isoprene polymerization. The catalytic activities are not strongly affected by the m…
Intrinsic luminescence and energy transfer processes in pure and doped YVO 4 crystals
2007
Luminescence properties of nominally pure and neodymium doped YVO4 single crystals have been studied by means of time-resolved luminescence spectroscopy technique. It was detected that, besides the main well-known blue excitonic emission band near 2.8 eV, an additional UV emission band at ∼3.1 eV appears in the spectra of intrinsic luminescence at low temperatures (∼80 K) for all crystals studied. Decay time of the UV band is much faster in comparison with the blue one and the UV band is quenched at temperatures above 150 K. Origin of the UV emission band is discussed. A significant rise front was observed in the relaxation kinetics of Nd3+ emission under band-to-band excitation. The time c…