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Synthesis and characterization of solvothermal processed calcium tungstate nanomaterials from alkoxide precursors

Chemistry of Materials

Boyle, Timothy J.; Yang, Pin Y.; Hattar, Khalid M.; Hernandez-Sanchez, Bernadette A.; Neville, Michael L.; Pratt, Sarah H.

An evaluation of calcium tungsten oxide (CaWO4) nanoparticles' properties was conducted using the powders generated from an all-alkoxide solvothermal (SOLVO) route. The reaction involved a toluene/pyridine mixture of tungsten(V) ethoxide ([W(OEt)5]) with calcium bis(trimethyl silyl) amide ([Ca(N(Si(CH3)3)2]) modified in situ by a series of alcohols (H-OR) including neo-pentanol (H-OCH2C(CH 3)3 or H-ONep) or sterically varied aryl alcohols (H-OC6H3R2-2,6 where R = CH3 (H-DMP), CH(CH3)2 (H-DIP), C(CH3)3 (DBP))]. Attempts to identify the intermediates generated from this series of reactions led to the crystallographic identification of [(OEt) 4W(μ-OEt)2Ca(DBP)2] (1). Each different SOLVO generated "initial" powder was found by transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD) to be nanomaterials roughly assigned as the scheelite phase (PDF 00-041-1431); however, these initial powders displayed no luminescent behavior as determined by photoluminescence (PL) measurements. Thermal processing of these powders at 450, 650, and 750 C yielded progressively larger and more crystalline scheelite nanoparticles. Both PL and cathodoluminescent (CL) emission (422-425 and 429 nm, respectively) were observed for the nanomaterials processed at 750 C. Ion beam induced luminescence (IBIL, 478 nm) appeared to be in agreement with these PL and CL measurements. Further processing of the materials at 1000 C, led to a coalescence of the particles and significant improvement in the observed PL (445 nm) and CL measurements; however, the IBIL spectrum of this material was significantly altered upon exposure. These data suggest that the smaller nanoparticles were more stable to radiation effects possibly due to the lack of energy deposits based on the short track length; whereas the larger particles appear to suffer from radiation induced structural defects. © 2013 American Chemical Society.

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TYPE Journal Article YEAR 2014
ScopusOSTIDOI

Synthesis of anticorrosion and antifouling nanoparticles for marine hydrokinetic technology

ACS National Meeting Book of Abstracts

Montoya, Laura; Hernandez-Sanchez, Bernadette A.; Zarick, Cory; Altman, Susan J.; Enos, David E.

Marine Hydrokinetic energy is the production of renewable electricity converted from the kinetic energy of ocean waves, current, tides, or by thermal gradients. Currently an emerging global industry is focused on developing novel technology to harness this sustainable power. These alternative energy devices require advances in anticorrosion and antibiofouling coatings to enhance lifetime and performance. In order to understand the microbial-nanomaterial interaction as well as nanomaterial corrosion process, we have elected to examine a variety of metallic, oxide and phosphate based nanomaterials. The synthesis of these materials using solution precipitation and solovothermal routes along with their full characterization will be presented.

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TYPE Conference YEAR 2011
ScopusOSTI

Ion beam characterization of advanced luminescent materials for application in radiation effects microscopy

Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms

Branson, J.V.; Hattar, K.; Rossi, P.; Vizkelethy, G.; Powell, Cody J.; Hernandez-Sanchez, Bernadette A.; Doyle, Barney L.

The ion photon emission microscope (IPEM) is a technique developed at Sandia National Laboratories (SNL) to study radiation effects in integrated circuits with high energy, heavy ions, such as those produced by the 88" cyclotron at Lawrence Berkeley National Laboratory (LBNL). In this method, an ion-luminescent film is used to produce photons from the point of ion impact. The photons emitted due to an ion impact are imaged on a position-sensitive detector to determine the location of a single event effect (SEE). Due to stringent resolution, intensity, wavelength, decay time, and radiation tolerance demands, an engineered material with very specific properties is required to act as the luminescent film. The requirements for this material are extensive. It must produce a high enough induced luminescent intensity so at least one photon is detected per ion hit. The emission wavelength must match the sensitivity of the detector used, and the luminescent decay time must be short enough to limit accidental coincidences. In addition, the material must be easy to handle and its luminescent properties must be tolerant to radiation damage. Materials studied for this application include plastic scintillators, GaN and GaN/InGaN quantum well structures, and lanthanide-activated ceramic phosphors. Results from characterization studies on these materials will be presented; including photoluminescence, cathodoluminescence, ion beam induced luminescence, luminescent decay times, and radiation damage. Results indicate that the ceramic phosphors are currently proving to be the ideal material for IPEM investigations.

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TYPE Conference YEAR 2011
ScopusOSTI
Results 51–100 of 117
Results 51–100 of 117