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Mixed Ionic and Electonic Conductors for Hydrogen Generation and Separation: A New Approach

Description: Composite mixed conductors comprising one electronic conducting phase, and one ionic conducting phase (MIECs) have been developed in this work. Such MIECs have applications in generating and separating hydrogen from hydrocarbon fuels at high process rates and high purities. The ionic conducting phase comprises of rare-earth doped ceria and the electronic conducting phase of rare-earth doped strontium titanate. These compositions are ideally suited for the hydrogen separation application. In the process studied in this project, steam at high temperatures is fed to one side of the MIEC membrane and hydrocarbon fuel or reformed hydrocarbon fuel to the other side of the membrane. Oxygen is transported from the steam side to the fuel side down the electrochemical potential gradient thereby enriching the steam side flow in hydrogen. The remnant water vapor can then be condensed to obtain high purity hydrogen. In this work we have shown that two-phase MIECs comprising rare-earth ceria as the ionic conductor and doped-strontium titanate as the electronic conductor are stable in the operating environment of the MIEC. Further, no adverse reaction products are formed when these phases are in contact at elevated temperatures. The composite MIECs have been characterized using a transient electrical conductivity relaxation technique to measure the oxygen chemical diffusivity and the surface exchange coefficient. Oxygen permeation and hydrogen generation rates have been measured under a range of process conditions and the results have been fit to a model which incorporates the oxygen chemical diffusivity and the surface exchange coefficient from the transient measurements.
Date: December 31, 2006
Creator: Gopalan, Srikanth
Partner: UNT Libraries Government Documents Department

(Ba,Sr)TiO{sub 3} dielectrics: Relationship between bulk and thin film properties

Description: Thin films of complex perovskites have a number of potentially important applications. Of major scientific and practical concern is the scaling of properties as film dimensions are reduced. This paper describes a satisfactory relationship between bulk and thin film dielectric properties of (Ba,Sr)TiO{sub 3}. Relative contributions of strain, A:B cation stoichiometry, and interface are separated to explain temperature dependent dielectric behavior.
Date: December 22, 1999
Creator: Kingon, A. I.; Streiffer, S. K.; Parker, C. B. & Stemmer, S.
Partner: UNT Libraries Government Documents Department

MOCVD growth and characterization of (Ba{sub x}Sr{sub 1{minus}x})Ti{sub 1+y}O{sub 3+z} thin films for high frequency devices

Description: The authors have investigated the structural and electrical characteristics of (Ba{sub x}Sr{sub 1{minus}x})Ti{sub 1+y}O{sub 3+z} (BST) thin films. The BST thin films were deposited at 650 C on platinized silicon with good thickness and composition uniformity using a large area, vertical liquid-delivery metalorganic chemical vapor deposition (MOCVD) system. The (Ba+Sr)/Ti ratio of the BST films was varied from 0.96 to 1.05 at a fixed Ba/Sr ratio of 70/30, as determined using x-ray fluorescence spectroscopy (XRF) and Rutherford backscattering spectrometry (RBS). Patterned Pt top electrodes were deposited onto the BST films at 350 C through a shadow mask using electron beam evaporation. Annealing the entire capacitor structure in air at 700 C after deposition of top electrodes resulted in a substantial reduction of the dielectric loss. Useful dielectric tunability as high as 2.3:1 was measured.
Date: January 18, 2000
Creator: Baumann, P. K.; Streiffer, S. K.; Im, J.; Baldo, P.; McCormick, A.; Auciello, O. et al.
Partner: UNT Libraries Government Documents Department

Defect Behaviors in Zinc Oxide and Zinc Titanates Ceramics from First Principles Computer Simulations

Description: ZnO and ZnO-TiO2 ceramics have intriguing electronic and mechanical properties and find applications in many fields. Many of these properties and applications rely on the understanding of defects and defect processes in these oxides as these defects control the electronic, catalytic and mechanical behaviors. The goal of this dissertation is to systematically study the defects and defects behaviors in Wurtzite ZnO and Ilmenite ZnTiO3 by using first principles calculations and classical simulations employing empirical potentials. Firstly, the behavior of intrinsic and extrinsic point defects in ZnO and ZnTiO3 ceramics were investigated. Secondly, the effect of different surface absorbents and surface defects on the workfunction of ZnO were studied using DFT calculations. The results show that increasing the surface coverage of hydrocarbons decreased the workfunction. Lastly, the stacking fault behaviors on ilmenite ZnTiO3 were investigated by calculating the Generalized Stacking Fault (GSF) energies using density functional theory based first principles calculations and classical calculations employing effective partial charge inter-atomic potentials. The gamma-surfaces of two low energy surfaces, (110) and (104), of ZnTiO3 were fully mapped and, together with other analysis such as ideal shear stress calculations.
Date: December 2016
Creator: Sun, Wei
Partner: UNT Libraries

AEM investigation of tetrahedrally coordinated Ti{sup 4+} in nickel-titanate spinel

Description: Stoichiometry and site distribution of metastable nickel-titanate spinel was studied with AEM. Results of EDXS and EELS agree that the metastable spinel is nonstoichiometric and titanium-deficient relative to its hypothetical endmember composition, ``Ni{sub 2}TiO{sub 4}``. The titanium deficiency has been determined by EELS to be {Delta} = 0.025 {plus_minus} 0.005. Channeling-enhanced microanalysis and ELNES studies indicate that the Ti{sup 4+} and Ni{sup 2+} cations are in tetrahedral and octahedral coordination, respectively, so that the metastable spinel has the normal cation distribution: Ti{sub l-{Delta}}[Ni{sub 2(1+{Delta})}]O{sub 4}. This is consistent with neutron powder-diffraction studies and SiO{sub 2}-solubility measurements of similar equilibrated and quenched spinel-containing specimens. Metastable nickel-titanate spinel therefore contrasts with stable stoichiometric spinels which tend to the inverse cation distribution, Me[MeTi]O{sub 4}.
Date: December 31, 1994
Creator: Anderson, I.M.; Bentley, J. & Carter, C.B.
Partner: UNT Libraries Government Documents Department

Test procedures and instructions for single shell tank saltcake cesium removal with crystalline silicotitanate

Description: This document provides specific test procedures and instructions to implement the test plan for the preparation and conduct of a cesium removal test, using Hanford Single Shell Tank Saltcake from tanks 24 t -BY- I 10, 24 1 -U- 108, 24 1 -U- 109, 24 1 -A- I 0 1, and 24 t - S-102, in a bench-scale column. The cesium sorbent to be tested is crystalline siticotitanate. The test plan for which this provides instructions is WHC-SD-RE-TP-024, Hanford Single Shell Tank Saltcake Cesium Removal Test Plan.
Date: January 7, 1997
Creator: Duncan, J.B.
Partner: UNT Libraries Government Documents Department

Gelcasting of aluminum titanate. Final report

Description: This Cooperative Research and Development Agreement (CRADA) was undertaken to assess the applicability of the gelcasting process for forming automotive exhaust port liner green bodies using Golden Technologies` proprietary aluminum titanate powder composition. A gelcasting process, specifically tailored to Golden Technologies` powder, was developed and used successfully to form green bodies for property evaluation. Using appropriate milling and firing conditions, it was found that the gelcast material had properties which compared favorably with Golden Technologies` baseline material. Tubular gelcast samples simulating exhaust port liners were prepared and shipped to Golden Technologies for final process evaluation.
Date: August 1, 1997
Creator: Nunn, S.D. & Stephan, J.E.
Partner: UNT Libraries Government Documents Department

Thermodynamic properties of solid solutions at high temperatures

Description: The research carried out under this cortract was concerned with the determination of thermodynamic properties of inorganic matenials at high temperatures. Experimental methods were developed which permit accurate and reliable determination of activity-composition relations in solid solutions, and stabilities of end-member compounds. The data provide insight irto the general laws governing the behavior of materials in high-temperature envirorments. The phases selected for the experimental studies include onthosilicates, metasilicates, oxides of periclase structure, spinels, and titarates. It has been shown that directions of conjugation lines between coexisting solid-solution phases provide a powerful tool for determnining relative stabilities of endmember compounds and activity-composition relations of solid solutions. In general, oxide phases (including silicates and titanates) forming complete solid-solution series at high temperatures show less deviations from ideality in their activity- composition relations than do alloy systems. Deviations from ideality are particularly small for many solid solutions of relatively simple structures (e.g. oxides of peniclase structure), whereas those of greater structural complexities (e.g. spinels) show larger deviations from ideality. (auth)
Date: January 1, 1973
Creator: Muan, A.
Partner: UNT Libraries Government Documents Department

Heteroepitaxy of perovskite ferroelectrics on silicon: a path to silicon-integrated ferroelectrics

Description: We have studied the thin-film heteroepitaxy between simple perovskite oxides and Si as it is accomplished with molecular beam epitaxy growth. Interface chemistry and electrostatics play critical roles in determining whether a commensurate interface develops. Submonolayer silicides are the required precursors for the transition to commensurate epitaxial oxide structures in these systems. This approach is illustrated with BaTiO{sub 3}; high crystalline perfection is achieved and resistivities as high as 10{sup 13} ohm-cm can be developed for BaTiO{sub 3} MOS capacitors on (001) Si. The epitaxy is (100)BaTiO{sub 3}//(001)Si with [0001]BaTiO{sub 3} aligned in plane with the polar axis along the [110] of Si. This epitaxy is dominated by a strong propensity for Ba to order along the [110] of Si during the submonolayer silicide formation. This commensurate heteroepitaxial growth leads to a truly monolithic crystal and attendant properties. 9 figs, 23 refs.
Date: October 1, 1996
Creator: McKee, R.A.; Walker, F.J. & Chisholm, M.F.
Partner: UNT Libraries Government Documents Department

Defect structure of semiconducting and insulating epitaxial oxides. Progress report, May 1, 1993--April 30, 1994

Description: The investigation has focused on epitaxial growth of BaSrTiO{sub 3} over the entire solid solution range, point defects in epitaxial BaTiO{sub 3} using temperature-dependent conductivity and deep-level optical spectroscopy, and their nonlinear optical properties.
Date: March 1, 1994
Creator: Wessels, B. W.
Partner: UNT Libraries Government Documents Department

Rotary Microfilter Media Evaluation

Description: Savannah River National Laboratory (SRNL) received funding from DOE EM-21, Office of Cleanup Technologies, to develop the rotary microfilter for high level radioactive service. One aspect of this project evaluated alternative filter media to select one for the 2nd generation rotary microfilter being procured as a prefilter to a small column ion exchange process. The authors conducted screening tests on a variety of filter media and pore sizes using a stirred cell followed by pilot-scale testing on a more limited number of filter media and pore sizes with a three disk rotary microfilter. These tests used 5.6 molar sodium supernate, and sludge plus monosodium titanate (MST) solids. The conclusions from this work are: (1) The 0.1 {micro} nominal TruMem{reg_sign} ceramic and the Pall PMM M050 (0.5 {micro} nominal) stainless steel filter media produced the highest flux in rotary filter testing. (2) The Pall PMM M050 media produced the highest flux of the stainless steel media tested in rotary filter testing. (3) The Pall PMM M050 media met filtrate quality requirements for the rotary filter. (4) The 0.1 {micro} TruMem{reg_sign} and 0.1 {micro} Pall PMM media met filtrate quality requirements as well. (5) The Pall PMM M050 media produced comparable flux to the 0.1 {micro} TruMem{reg_sign} media, and proved more durable and easier to weld. Based on these test results, the authors recommend Pall PMM M050 filter media for the 2nd generation rotary microfilter.
Date: April 20, 2005
Creator: Poirier, M
Partner: UNT Libraries Government Documents Department

TESTING OF BASELINE AND LAMINATED FILTER DISKS USING MST AND MMST WITH A PILOT SCALE ROTARY FILTER

Description: Testing was completed to compare the filtration performance of modified monosodium titanate (mMST) with that of monosodium titanate (MST) with the rotary microfilter. In addition, the performance of the new laminated filter disk was compared to that of the original baseline welded filter disk. Results showed that flux rates for mMST exceeded that of MST with both the baseline and laminated filter disks in deployment concentrations of 0.2 g/L of mMST and 0.4 g/L of MST. The filtration rate of the mMST with the laminated filter disk exceeded that of the baseline filter disk. However, the baseline filter disk filtration rate for MST was greater than that of the laminated disk. The measured sample turbidity for all tests was 1.06 NTU or less. A contract was established with SpinTek Filtration{trademark} to operate a 3-disk pilot scale unit with prototypic filter disks and various feeds and two different filter disk membranes. SpinTek evaluated a set of the baseline 0.5 micron filter disks as well as a set of laminated filter disks using the same 0.5 micron filter disks. The membrane used for both disk sets was manufactured by the Pall Corporation (PMM 050). Each set of disks was run with monosodium titanate (MST) and modified monosodium titanate (mMST). Throughout the testing, samples of the filtrate were collected and measured for turbidity.
Date: December 19, 2001
Creator: Herman, D.
Partner: UNT Libraries Government Documents Department

Localized temperature stability in Low Temperature Cofired Ceramics (LTCC).

Description: The base dielectrics of commercial low temperature cofired ceramics (LTCC) systems have a temperature coefficient of resonant frequency ({tau}{sub f}) in the range -50 {approx} -80 ppm/C. In this research we explored a method to realize zero or near zero {tau}{sub f} resonators by incorporating {tau}{sub f} compensating materials locally into a multilayer LTCC structure. To select composition for {tau}{sub f} adjustment, {tau}{sub f} compensating materials with different amount of titanates were formulated, synthesized, and characterized. Chemical interactions and physical compatibility between the {tau}{sub f} modifiers and the host LTCC dielectrics were investigated. Studies on stripline (SL) resonator panels with multiple compensating dielectrics revealed that: 1) compositions using SrTiO{sub 3} provide the largest {tau}{sub f} adjustment among titanates, 2) the {tau}{sub f} compensation is proportional to the amount of SrTiO{sub 3} in compensating materials, as well as the thickness of the compensating layer, and 3) the most effective {tau}{sub f} compensation is achieved when the compensating dielectric is integrated next to the SL. Using the effective dielectric constant of a heterogeneous layered dielectric structure, results from Method of Momentum (MoM) electromagnetic simulations are consistent with the experimental observations.
Date: April 1, 2012
Creator: Dai, Steven Xunhu & Hsieh, Lung-Hwa.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #03031

Description: Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot 030311 qualification and 9 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process. Harrell Industries is under contract with Savannah River Remediation to provide MST for use in the Actinide Removal Process (ARP). A 500-mL qualification sample for Lot 030311 was sent to the Savannah River National Laboratory (SRNL) to confirm the material meets the requirements specified in the purchase specification. The vendor is also obligated to send verification samples from {approx}10% or more of the pails of MST product for each lot (distributed roughly evenly through the entire lot of pails). For the verification of this lot, Harrell Industries sent 9 samples, one each from pails 1, 5, 15, 20, 25, 30, 40, 45, and 55 of 59 total pails.
Date: May 16, 2011
Creator: Taylor-Pashow, K.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #050411

Description: Harrell Industries is under contract with Savannah River Remediation to provide Monosodium titanate (MST) for use in the Actinide Removal Process (ARP). A 500-mL qualification sample for Lot 050411 was sent to the Savannah River National Laboratory (SRNL) to confirm the material meets the requirements specified in the purchase specification. The vendor is also obligated to send verification samples from {approx}10% or more of the pails of MST product for each lot (distributed roughly evenly through the entire lot of pails). For the verification of this lot, Harrell Industries sent 12 samples, one each from pails No.1, 10, 20, 30, 40, 60, 70, 80, 90, 100, 110, and 120 of 120 total pails. MST for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot 050411 qualification and 12 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process.
Date: June 28, 2011
Creator: Taylor-Pashow, K.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #052511

Description: Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.052511 qualification and 14 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process.
Date: August 22, 2011
Creator: Taylor-Pashow, K.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #071311

Description: Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.071311 qualification and 12 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process.
Date: October 4, 2011
Creator: Taylor-Pashow, K.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #081811

Description: Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.081811 qualification and 12 verification samples met all the requirements in the specification, with the possible exception of the geometric standard deviation for particle size. Two subsamples from the qualification sample were analyzed, giving results of 3.82 and 3.28, respectively, for the geometric standard deviation. The specification is {le}3.5. The results for both samples met the remaining particle size specifications, i.e. <10 vol% below 0.8 {mu}m and <1 vol% above 37 {mu}m. Filtration behavior of the current batch is expected to be near that of recent batches. SRNL recommends acceptance of this material. SRNL also recommends performing a statistical review of particle size data for the MST lots from this vendor to assess whether an improved material specification is appropriate.
Date: October 28, 2011
Creator: Taylor-Pashow, K. & Fink, S.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #120111

Description: Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.120111 qualification and the first 12 verification samples met all the requirements in the specification indicating the material is acceptable for use in the process. Analyses of Pail 125 verification sample fails the criteria for solids content and has measurably lower pH, density, and total bottle weight. The verification sample for Pail 125 was retested for weight percent solids after checking that all of the solids had been suspended. The sample again failed to meet acceptance criteria. SRNL recommends accepting Pails 1 through 120. Pails 121 through 125 should be rejected and returned to the vendor.
Date: February 21, 2012
Creator: Shehee, T.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF HARRELL MONOSODIUM TITANATE LOT #46000524120

Description: Monosodium titanate (MST) for use in the Actinide Removal Process (ARP) must be qualified and verified in advance. A single qualification sample for each batch of material is sent to SRNL for analysis, as well as a statistical sampling of verification samples. The Harrell Industries Lot No.46000524120 qualification and the 14 verification samples met each of the selected specification requirements that were tested and, consequently, the material is acceptable for use in the ARP process.
Date: August 29, 2012
Creator: Taylor-Pashow, K.
Partner: UNT Libraries Government Documents Department

Ductile grinding of Ba(Sr)TiO{sub 3} detector substrates

Description: Several precision machining techniques have been applied to barium strontium titanate wafers as deterministic replacements for lapping, polishing and reticulation. Surface finishes approaching polish quality have been achieved in less time than normally required, leading to potentially lower manufacturing costs for uncooled FPA`s.
Date: August 1, 1994
Creator: Kahl, W.K.
Partner: UNT Libraries Government Documents Department

Development and testing of spheroidal inorganic sorbents

Description: Objective was to develop sodium titanate (ST) microspheres, made by the HMTA (hexamethylenetetramine) internal gelation process, to remove radionuclides and heavy metals from waste streams at DOE sites. to determine the optimum amount of ST that can be embedded in hydrous Ti oxide (HTO) microspheres, batches of 9.2 to 23.3% ST in HTO were prepared. Crush strength of the air-dried microspheres was found to be highest. Sr was removed from simulated supernatant by all composite microspheres; 13.2% ST/HTO worked best.
Date: December 3, 1996
Creator: Collins, J.L.; Egan, B.Z. & Anderson, K.K.
Partner: UNT Libraries Government Documents Department