Chris Wetteland

University of Tennessee at Knoxville | UTK · Department of Materials Science and Engineering

Ion beam analyses were completed on single crystal LiD (lithium hydride with deuterium on the hydrogen sites) to determine products of hydrolysis with decarbonated H 2 O (with protium-hydrogen) in an inert gas. Rutherford backscattering spectrometry showed movement of oxygen into the bulk of LiD samples. Hydrolysis rates for the single crystal LiD...

Metal-ceramic composites consisting of vanadium (V) metal and magnesio-aluminate spinel (MgAl2O4) ceramic were developed for high radiation applications. A number of powder processing routes (presented in Part I) were followed that yielded composites with different properties. Results obtained from X-ray diffraction, electron microscopy and mechani...

Exposure of polytetrafluoroethylene (PTFE) to α-radiation was investigated to determine the physical and chemical effects, as well as to compare and contrast the damage mechanisms with other radiation types (β, γ, or thermal neutron). A number of techniques were used to investigate the chemical and physical changes in PTFE after exposure to α-radia...

Microstructural evolution with the change in thickness of superconducting YBa₂Cu₃O_7-X films on single-crystal SrTiO₃ substrates deposited by pulsed laser deposition was evaluated using different structural characterization tools. A noticeable degradation of crystallinity with the increased film thickness...

The morphology, chemical composition, and mechanical properties in the surface region of α-irradiated polytetrafluoroethylene (PTFE) have been examined and compared to unirradiated specimens. Samples were irradiated with 5.5 MeV ⁴He²⁺ ions from a tandem accelerator to doses between 1 × 10⁶ and 5 × 10¹⁰ Rad. Static time-of-flight secondary ion mass...

Experiments were performed to study the radiation tolerance and mechanical stability of polytetrafluoroethylene (PTFE) loaded polyetheretherketone (PEEK) exposed to alpha particle radiation. Accelerator generated alpha beams were used to provide the extreme upper limit for the radiation environment of actinide sources where the polymer is employed...

The structural degradation of polytetrafluoroethylene (PTFE) upon irradiation with MeV alpha (α) particles is accompanied by the proliferation of hydrogenated and oxygen-functionalized fluorocarbon species. In this article, we explore the origin of monoxide- and dioxide-functionalized fluorocarbon species that emerge upon α particle irradiation of...

Rutherford backscattering in the axial channeling configuration was used together with cross-sectional transmission electron microscopy (XTEM) to investigate the near surface damage introduced to (100) ZnSe by mechanical polishing. ZnSe surfaces were prepared by polishing with 1μm and 1/4μm diamond abrasive slurries, and by etching so as to provide...

The chemical evolution of poly(tetrafluoroethylene) (PTFE) that is brought about by increasing levels of irradiation with alpha particles is accompanied by the emergence and proliferation of functionalized moieties. Families of reaction products specifically identified in the alpha-irradiated polymer matrix include hydride-, hydroxide-, and oxide-f...

Ion beam interactions with many ceramics produce strong luminescence, which may be collected and analyzed to observe radiation damage effects. Exposure to radiation in these environments can cause transitions between periodic and aperiodic microstructures, and thus affect the microstructural characteristics of the materials. However, little is know...

This new project relies on the capabilities collocated at Los Alamos in the Trident laser facility of long-pulse laser drive, for laser-plasma formation, and high-intensity short-pulse laser drive, for relativistic laser-matter interaction experiments. Specifically, we are working to understand quantitatively the physics that underlie the generatio...

The surface structure of polytetrafluoroethylene (PTFE) upon α-particle irradiation has been investigated at doses in the range of 1 × 107 to 1 × 1011 Rad and compared with the surface structure of the unirradiated polymer. Both neat and 25% fiberglass content PTFE were studied. The samples, maintained at nominal room temperature, were irradiated i...

We conducted a comparative study of microstructural properties for YBa2Cu3O7 (YBCO) films on single-crystal MgO and polycrystalline Ni-based metal substrates with ion-beam-assisted deposited (IBAD) MgO as a template. The film grown on the metal substrate shows more crystalline imperfections with density of screw dislocations four times higher than...

Irradiation of polymer samples using an accelerated beam of He++ ions passed through a 10 μm thick window of havar foil, has been performed. Such an irradiation simulates the effects of large α radiation doses, on a vastly reduced time-scale. The experimental set up was designed to allow analysis of volatiles evolved from the irradiated samples by...

We propose a method to improve accurate determination of damage/impurity depth profiles by channeling Rutherford backscattering by using beams in an energy window of 400–800 keV. This is based on the study of the stopping power of ions as a function of incident energy along the Si 〈100〉 axis, which shows that the channeling stopping power within th...

Experimentally investigating ageing caused by irradiation with energetic particles is very difficult. Radioactive sources can be employed but these are difficult to handle and contaminate the material being irradiated precluding subsequent chemical and physical characterisation. The penetration of energetic particles also tends to be small so any c...

Polycrystalline pellets of the sesquioxide Dy2O3 were irradiated at cryogenic temperature with Kr++ ions to a fluence of 1 × 1020 Kr/m2. The crystal structure of the irradiated Dy2O3 was observed to change from a cubic, so-called C-type rare-earth sesquioxide structure to a monoclinic, B-type rare-earth sesquioxide structure upon ion irradiation. T...

Bulk austenitic stainless steels (SS) have a face-centered cubic (fcc) structure. However, sputter deposited films synthesized using austenitic stainless steel targets usually exhibit body-centered cubic (bcc) structure or a mixture of fcc and bcc phases. This paper presents studies on the effect of processing parameters on the phase stability of 3...

Surfaces of bulk single crystal CdS, ZnSe and ZnO were prepared by mechanical polishing with 1 and 1/4 mum diamond abrasive slurries and by chemomechanical polishing with sodium hypochlorite:colloidal silica. Etched surfaces, indicative of original crystalline quality were also prepared. Near surface damage was investigated by ion channeling with H...

Hydrogen isotope thin film standards have been manufactured at Sandia National Laboratories for use by the materials characterization community. Several considerations were taken into account during the manufacture of the ErHD standards, with accuracy and stability being the most important. The standards were fabricated by e-beam deposition of Er o...

The relationship between the structure and mechanical properties of sputter-deposited boron carbide films was investigated. Changes in the structure induced by annealing were characterized in terms of chemical composition, chemical bonding, and concentrations of defects and trapped impurities. The creation of intericosahedral chains for higher anne...

This laboratory study seeks to define Laser Induced Breakdown Spectroscopy (LIBS) capabilities for planetary surface analysis by demonstrating the suitability of in-situ LIBS for determining the compositions of extraterrestrial samples by comparative elemental analyses of meteorite samples.

The relationship between structure and mechanical properties of sputter-deposited boron carbide films was investigated. Changes in the structure induced by annealing were characterized in terms of chemical composition, chemical bonding and concentrations of defects and of trapped impurities. The creation of new intericosahedral chains for higher an...

Metal oxides such as zirconia and hafnia are being investigated as new materials for application as gate dielectrics in future complementary metal-oxide-semiconductor devices. In this paper, we present results on oxidation of metal films such as Zr, Hf, and Al by the ultraviolet (UV) ozone oxidation method. A nuclear reaction analysis technique, th...

The irradiation effects of 4.9MeV protons on salt repository related brines are investigated spectrophotometrically. The induced formation of hypochlorous acid is determined up to doses of 11kGy in 3.7M MgCl2·6H2O and in a multicomponent brine of high concentration: Brine G. The build-up of hypochlorous acid to a steady-state concentration is found...

In this work we show the feasibility of producing silicon nanocrystals by means of a new method based on the oxi-reduction of silicon dioxide induced by the presence of an impurity and annealing. The choice of magnesium as the impurity relies on its chemical properties of oxi-reducing the SiO2 matrix while avoiding the formation of Si-based compoun...

MgAl2O4-spinel has been widely investigated as inert matrix for actinide-transmutation. Under impact of fission fragments, it becomes amorphous. During reactor irradiation, crystalline and amorphous spinel are expected in the fuel, containing, among others xenon and helium. Gas-release measurements and positron beam analysis (PBA) were performed on...

Thermally stimulated luminescence and emission spectra of cerium-doped Lu2SiO5 have been measured in the temperature interval 10K ⩽ T ⩽ 310K. Eight glow peaks occur with the most intense peak exhibiting a maximum at 306 K. Data analyses show that the peaks generally obey first-order kinetics with thermal activation energies ranging from 0.085 to 0....

Thermally stimulated luminescence and emission spectra of cerium-doped Lu2SiO5 have been measured in the temperature interval 10 K less than or equal to T less than or equal to 310 K. Eight glow peaks occur with the most intense peak exhibiting a maximum at 306 K. Data analyses show that the peaks generally obey first-order kinetics with thermal ac...

Studies of sulfides in Allende show that pyrrhotite occurs mainly within chondrules and has been partially replaced by pentlandite. Ni and Co contents of pentlandites within individual chondrules are homogeneous, but are variable between chondrules. Additional information is contained in the original extended abstract.

The formation of superconducting YBa2Cu3O7–x (Y123) by in situ pulsed laser deposition from a stoichiometric Y123 target typically requires an oxygen-ambient environment (P ˜ 100–300-mtorr O2) and appropriate substrate temperature during deposition. We have found that pulsed laser deposition from a Y123 target in vacuo onto a (001) LaAlO3 substrate...

Because geological salt formations are considered possible sites for radioactive waste disposal, plausible inundation scenario of salt repository will allow chloride brines to be formed, which consequently will be exposed to radiation from the waste. Key radioelements in Intermediate Level Waste (ILW),H igh Level Waste (HLW) or TRU waste have been...

The photoluminescence (PL) response of single crystal ZnO subjected to mechanical and chemo-mechanical polishing has been investigated. Zn-terminated and O-terminated surfaces of (0001)-oriented ZnO crystals were prepared by mechanical polishing with 1/4 μm and 1 μm diamond abrasives and by chemomechanical polishing. The spectrally resolved room te...

Many factors such as impurities in the oxide and metal, microstructure, gas impurities, and oxide thickness may influence the rate and location of the nucleation of hydride on uranium. This work has concentrated on isolating one of these variables, the oxide thickness, and measuring the effect of the oxide thickness on uranium hydride nucleation. U...

Z-cut lithium tantalate (LiTaO{sub 3}) ferroelectric single crystals were irradiated with 200 keV Ar{sup ++} ions. LiTaO{sub 3} possesses a structure that is a derivative of the corundum (Al{sub 2}O{sub 3}) crystal structure. A systematic study of the radiation damage accumulation rate as a function of ion dose was performed using ion-beam channeli...

Resonant backscattering is widely used to improve the detection limit of the light elements such as B, C, N and O. One disadvantage, however, is that several incident energies are normally needed if the sample contains a number of the light elements. There are ``magic'' energies at which several light elements can be detected simultaneously with su...

Z-cut lithium tantalate (LiTaO3) ferroelectric single crystals were irradiated with 200 keV Art ions. LiTaO3 possesses a structure that is a derivative of the corundum (A1 20 3) crystal structure. A systematic study of the radiation damage accumulation rate as a function of ion dose was performed using ion-beam channeling experiments. An ion fluenc...

This article proposes an option for both reactor and weapons-grade plutonium disposition that incorporates both aspects of the dual-track strategy. The burn and bury concepts offers an efficient means of oreduce the world plutonium inventory as well as to reduce security risks. This cradle-to-grave fuel cycle concept represents a new paradigm for a...

The mechanical properties of Xe-implanted spinel and cubic zirconia surfaces, as determined by nano-indentation measurements, are distinct and the differences can be related to their microstructures. Upon Xe(2+) ion irradiation at cryogenic temperature (120K), the Young`s modulus of irradiated spinel increases slightly (a few percent) then falls dr...

Radiation damage accumulation in the rutile phase of titanium dioxide (TiO2) have been studied by Rutherford Backscattering Spectroscopy in channeling geometry (RBS/c) and by transmission electron microscopy (TEM). A large temperature dependence of damage accumulation in rutile was observed. Defect accumulation determined in situ by RBS/c occurs fa...

The radiation response of α-Al2O3 (R3̄c), FeTiO3 (R3), MgTiO3 (R3), and LiTaO3 (R3c) was investigated using 200 keV Ar2+ and 1 MeV Kr+ and a combination of Rutherford backscattering spectrometry and transmission electron microscopy. All of these materials have the corundum or a corundum-derivative crystal structure. This family of oxides is of inte...

Metal-ceramic composites consisting of vanadium (V) metal and magnesio-aluminate spinel (MgAl2O4) ceramic were developed for high radiation applications. A number of powder processing routes (presented in Part I) were followed that yielded composites with different properties. Results obtained from X-ray diffraction, electron microscopy and mechani...

Vanadium-spinel composites are promising materials for structural applications in radiation environments. Powders of two vanadium-spinel composites, 20/80 vol.%, were prepared by (a) ball milling mixtures of vanadium and spinel powders (alloy VSLP) and (b) through a self-sustained reaction synthesis of vanadium, MgO, and Al powders (alloy VSHP). Th...

While degassing hydrogen at an elevated temperature (>600 C) can reduce the chance of Q degradation (Q disease), eliminating this process would significantly reduce the cost and time of producing cavities. Past published data elsewhere have shown significant Q disease at relatively low frequencies such as the 130 MHz quarter-wave resonator at JAERI...

In the event of inundation of a nuclear waste repository located in a geological salt formation, chloride brines in contact with nuclear waste will be exposed to different kind of radiation depending on waste-form conditions. Ionizing radiations, however, have the ability to significantly affect the groundwater chemistry of the brines through the f...

Resonant backscattering is widely used to improve the detection limit of the light elements such as B, C, N and O. One disadvantage, however, is that several incident energies are normally needed if the sample contains a number of the light elements. There are [open quotes]magic[close quotes] energies at which several light elements can be detected...

Corrosion layer growth in LiH can be monitored by RBS; alpha beams affect the LiH material, causing enhanced corrosion in irradiated regions. {sm_bullet} O and C chemistries show wide variation across the LiH powder compacts studied. {sm_bullet} The O growth for a LiH reaction with HO (with or without C) shows an initial rise, followed by a linear...

The United States Department of Energy (DOE) has â1 billion pounds of surplus depleted uranium (i.e., uranium tails) from uranium gaseous diffusion enrichment facilities. Rather than treating this material as waste, DOE is investigating potential beneficial uses for this uranium. Of the many possible uses, uranium dioxide (UO2) has properties that...