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in subjects: "Sapphire"

open access

Healing of lithographically introduced flaws in glass and glass containing ceramics

The morphological evolution of cylindrical pores or ``channels`` and crack-like cavities in glass and glass-containing ceramics at elevated temperatures was studied. The systems studied were: Coming 7056 alkali borosilicate glass, soda-lime glass (microscope slides), a commercially available 96% Al{sub 2}O{sub 3}with {approx}5--10% intergranular glass, 96% Al{sub 2}O{sub 3} bonded to sapphire, and a model sapphire/glass/sapphire system fabricated by diffusion bonding etched and unetched pieces … more

Date: December 1, 1992

Creator: Ackler, H. D.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Healing of lithographically introduced flaws in glass and glass containing ceramics

The morphological evolution of cylindrical pores or channels'' and crack-like cavities in glass and glass-containing ceramics at elevated temperatures was studied. The systems studied were: Coming 7056 alkali borosilicate glass, soda-lime glass (microscope slides), a commercially available 96% Al[sub 2]O[sub 3]with [approx]5--10% intergranular glass, 96% Al[sub 2]O[sub 3] bonded to sapphire, and a model sapphire/glass/sapphire system fabricated by diffusion bonding etched and unetched pieces of… more

Date: December 1, 1992

Creator: Ackler, H. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Shock temperatures in metals. Final report, March 29, 1977-September 30, 1978

A system for measurement of the spectral radiace of materials shocked to high pressures (approx. 100 GPa) by impact using a light-gas gun is described. Thermal radiation from the sample is sampled at six wavelength bands in the visible spectrum, and each signal is separately detected by solid state photodiodes and recorded with a time resolution of approx. 10 ns. Interpretation of the records in terms of temperature of transparent sample materials is discussed. Results of a series of explorator… more

Date: January 1, 1978

Creator: Ahrens, T.J. & Lyzenga, G.A.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

GaN Stress Evolution During Metal-Organic Chemical Vapor Deposition

The evolution of stress in gallium nitride films on sapphire has been measured in real- time during metal organic chemical vapor deposition. In spite of the 161%0 compressive lattice mismatch of GaN to sapphire, we find that GaN consistently grows in tension at 1050"C. Furthermore, in-situ stress monitoring indicates that there is no measurable relaxation of the tensile growth stress during annealing or thermal cycling.

Date: October 14, 1998

Creator: Amano, H.; Chason, E.; Figiel, J.; Floro, J.A.; Han, J.; Hearne, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Low-Dislocation-Density GaN from a Single Growth on a Textured Substrate

The density of threading dislocations (TD) in GaN grown directly on flat sapphire substrates is typically greater than 10{sup 9}/cm{sup 2}. Such high dislocation densities degrade both the electronic and photonic properties of the material. The density of dislocations can be decreased by orders of magnitude using cantilever epitaxy (CE), which employs prepatterned sapphire substrates to provide reduced-dimension mesa regions for nucleation and etched trenches between them for suspended lateral … more

Date: July 31, 2000

Creator: Ashby, Carol I.; Willan, Christine C.; Han, Jung; Missert, Nancy A.; Provencio, Paula P.; Follstaedt, David M. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

DEVELOPMENT OF NEW MID-INFRARED ULTRAFAST LASER SOURCES FOR COMPACT COHERENT X-RAY SOURCES

In this project, we proposed to develop laser based mid-infrared lasers as a potentially robust and reliable source of ultrafast pulses in the mid-infrared region of the spectrum, and to apply this light source to generating bright, coherent, femtosecond-to-attosecond x-ray beams.

Date: May 14, 2012

Creator: Backus, Sterling

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

An LLNL perspective on ASCI data mining and pattern recognition requirements

The working document has been put together by the members of the Sapphire project at LLNL. The goal of Sapphire is to apply and extend techniques from data mining and pattern recognition in order to detect automatically the areas of interest in very large data sets. The intent is to help scientists address the problem of data overload by providing them effective and efficient ways of exploring and analyzing massive data sets. One of the key areas where they expect this technology to be used is … more

Date: January 1, 1999

Creator: Baldwin, Chuck; Kamath, Chandrika & Musick, Ron

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ultrashort-pulse lasers machining

A new type of material processing is enabled with ultrashort (t < 10 psec) laser pulses. Cutting, drilling, sculpting of all materials (biologic materials, ceramics, sapphire, silicon carbide, diamond, metals) occurs by new mechanisms which eliminate thermal shock or collateral damage. High precision machining to submicron tolerances is enabled resulting in high surface quality and negligible heat affected zone.

Date: January 22, 1999

Creator: Banks, P S; Feit, M D; Nguyen, H T & Perry, M D, Stuart, B C

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Functionally Gradient Materials for Thermal Barrier Coatings in Advanced Gas Turbine Systems

New designs for advanced gas turbine engines for power production are required to have higher operating temperatures in order to increase efficiency. However, elevated temperatures will increase the magnitude and severity of environmental degradation of critical turbine components (e.g. combustor parts, turbine blades, etc.). To offset this problem, the usage of thermal barrier coatings (TBCs) has become popular by allowing an increase in maximum inlet temperatures for an operating engine. Alth… more

Date: December 31, 1995

Creator: Banovic, Stephen W.; Chan, Helen M.; Marder, Arnold R.; Puerta, Douglas G.; Barmak, Katayun; Harmer, Martin P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The Mechanical Properties of Alumina Films Formed by Plasma Deposition and by Ion Irradiation of Sapphire

This paper examines the correlation between mechanical properties and the density, phase, and hydrogen content of deposited alumina layers, and compares them to those of sapphire and amorphous alumina synthesized through ion-beam irradiation of sapphire. Alumina films were deposited using electron beam evaporation of aluminum and co-bombardment with O{sub 2}{sup +} ions (30-230 eV) from an electron cyclotron resonance (ECR) plasma. The H content and phase were controlled by varying the depositi… more

Date: July 16, 1999

Creator: Barbour, J.C.; Follstaedt, D.M.; Knapp, J.A.; Linam, D.L.; Mayer, T.M. & Minor, K.G.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Modified embedded atom method calculations of interfaces

The Embedded Atom Method (EAM) is a semi-empirical calculational method developed a decade ago to calculate the properties of metallic systems. By including many-body effects this method has proven to be quite accurate in predicting bulk and surface properties of metals and alloys. Recent modifications have extended this applicability to a large number of elements in the periodic table. For example the modified EAM (MEAM) is able to include the bond-bending forces necessary to explain the elast… more

Date: May 1, 1996

Creator: Baskes, M.I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Improved Characterization of Transmitted Wavefront Error on CADB Epoxy-Free Bonded Solid State Laser Materials

Current state-of-the-art and next generation laser systems - such as those used in the NIF and LIFE experiments at LLNL - depend on ever larger optical elements. The need for wide aperture optics that are tolerant of high power has placed many demands on material growers for such diverse materials as crystalline sapphire, quartz, and laser host materials. For such materials, it is either prohibitively expensive or even physically impossible to fabricate monolithic pieces with the required size.… more

Date: December 9, 2010

Creator: Bayramian, A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Frequency Conversion Activation on the Mercury Laser

High efficiency frequency conversion while operating at average power is critical for the Mercury laser. We will demonstrate average power frequency conversion of face-cooled DKDP and YCOB crystals using a sapphire heat spreader approach.

Date: September 24, 2004

Creator: Bayramian, A. J.; Beach, R. J.; Bibeau, C.; Campbell, R.; Ebbers, C. A.; Freitas, B. L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation of the {sup 4}I{sub 11/2} terminal level lifetime for several neodymium-doped laser crystals and glasses

All models of lasing action require knowledge of the physical parameters involved, of which many can be measured or estimated. The value of the terminal level lifetime is an important parameter in modeling many high power laser systems since the terminal level lifetime can have a substantial impact on the extraction efficiency of the system. However, the values of the terminal level lifetimes for a number of important laser materials such as ND:YAG and ND:YLF are not well known. The terminal le… more

Date: April 25, 1995

Creator: Bibeau, C.

Item Type: Thesis or Dissertation

Partner: UNT Libraries Government Documents Department

open access

Surface Impedance Measurements of Single Crystal MgB2 Films for Radiofrequency Superconductivity Applications

We report microstructure analyses and superconducting radiofrequency (SRF) measurements of large scale epitaxial MgB{sub 2} films. MgB{sub 2} films on 5 cm dia. sapphire disks were fabricated by a Hybrid Physical Chemical Vapor Deposition (HPCVD) technique. The electron-beam backscattering diffraction (EBSD) results suggest that the film is a single crystal complying with a MgB{sub 2}(0001) {parallel} Al{sub 2}O{sub 3}(0001) epitaxial relationship. The SRF properties of different film thickness… more

Date: July 1, 2012

Creator: Binping Xiao, Xin Zhao, Joshua Spradlin, Charles Reece, Michael Kelley, Teng Tan, Xi Xiaoxing

Item Type: Article

Partner: UNT Libraries Government Documents Department

captions transcript

[Black Tie Dinner, October 22, 2005]

Recording of the 24th Annual Dallas Fort Worth Black Tie Dinner, that raises money and awareness for current GLBT/LGBT issues and organizations. The theme of the dinner was "Imagine Tomorrow" and used kaleidoscopes to inspire much of the design. The opening of the video includes words from the beneficiaries of the event, followed by a performance of a medley of John Lennon's "Imagine" with Colm Wilkinson and Linda Eder's "A New Life". The co-chairs, Tom Phipps and Pam Clayton, then announce spe… more

Date: October 22, 2005

Duration: 1 hour 2 minutes 37 seconds

Creator: Black Tie Dinner, Inc.

Item Type: Video

Location: 32.785134 -96.794877

Partner: UNT Libraries Special Collections

open access

Copper Wetting of x-Al(2)O(3)(0001): Theory and Experiment

XPS studies have been carried out on sputter deposited copper on a substantially hydroxylated {alpha}-Al{sub 2}O{sub 3}(0001) (sapphire) surface under ultra-high vacuum (UHV) conditions. XPS-derived Cu uptake curves show a sharp change in slope at a coverage of 0.35 monolayer (on a Cu/O atomic basis), indicative of initial layer-by-layer growth. CU(LMM) lineshape data indicate that, prior to the first break in the curve, Cu is oxidized to Cu(I). At higher coverages, metallic CU(0) is. observed.… more

Date: August 10, 1999

Creator: Bogicevic, A.; Jennison, D. R.; Kelber, J. A.; Niu, Chengyu & Shepherd, K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Hydrogenation of Dislocation-Limited Heteroepitaxial Silicon Solar Cells: Preprint

Post-deposition hydrogenation by remote plasma significantly improves performance of heteroepitaxial silicon solar cells. Heteroepitaxial deposition of thin crystal silicon on sapphire for photovoltaics (PV) is an excellent model system for the study and improvement of deposition on inexpensive Al2O3-coated (100) biaxially-textured metal foils. Without hydrogenation, PV conversion efficiencies are less than 1% on our model system. Performance is limited by carrier recombination at electrically … more

Date: June 1, 2012

Creator: Bolen, M. L.; Grover, S.; Teplin, C. W.; Bobela, D.; Branz, H. M. & Stradins, P.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chirped-Pulse Amplification with flashlamp-pumped Ti:Sapphire amplifiers

Ti:Sapphire (Ti:Al{sub 2}O{sub 3}) amplifier stages are typically pumped with Q-switched Nd:YAG lasers doubled to 532 nm because of good spectral overlap, short temporal width, high repetition rate (i.e., 10 Hz to > 5 kHz) and the problems associated with flashlamp pumping a material with a relatively short upper state lifetime. Limitations to this pumping method arise due to the 1 to 1.5 joule/pulse ceiling found in most commercial high rep rate Nd:YAG lasers. The availability of high quality,… more

Date: January 1, 1994

Creator: Bonlie, J. D.; White, W. E.; Price, D. F. & Reitze, D. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chirped-Pulse Amplification with flashlamp-pumped Ti:Sapphire amplifiers. Revision 1

Date: January 1, 1994

Creator: Bonlie, J. D.; White, W. E.; Price, D. F. & Reitze, D. H.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Undergraduate research semester internship fall 1999 abstracts and research papers

The Undergraduate Research Semester (URS) program provides a unique and challenging off-campus research opportunity for upper-division university undergraduate and pre-grad-school students in science, mathematics, and engineering. This internship program is a partnership between Lawrence Livermore National Laboratory, Sandia National Laboratories (New Mexico and California), and Los Alamos National Laboratory, to provide 75+ (annually) science and engineering undergraduates a rich research expe… more

Date: December 1, 1999

Creator: Brown, S.; Capaldi, L.; Garcia, M. A.; Kahn, S. S.; Monbleau, D. N.; Nault, D. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Correlation between structure and electrical transport in ion-irradiated graphene grown on Cu foils

Graphene grown by chemical vapor deposition and supported on SiO2 and sapphire substrates was studied following controlled introduction of defects induced by 35 keV carbon ion irradiation. Changes in Raman spectra following fluences ranging from 1012 cm-2 to 1015 cm-2 indicate that the structure of graphene evolves from a highly-ordered layer, to a patchwork of disordered domains, to an essentially amorphous film. These structural changes result in a dramatic decrease in the Hall mobility by or… more

Date: November 4, 2010

Creator: Buchowicz, G.; Stone, P. R.; Robinson, J. T.; Cress, C. D.; Beeman, J. W. & Dubon, O. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Sizing single crystal sapphire

Although there are several significant advantages to using single crystal sapphire as substrate material for hybrid microcircuits, the sizing of this material can be far more troublesome than the sizing of alternate material, such as polycrystal alumina. The work done in developing a satisfactory method of sizing single crystal sapphire is described. The results of sizing using grinding wheels, wire saws, and laser scribers are given. It was concluded that laser scribing is a viable method of s… more

Date: March 1, 1976

Creator: Bushmire, D. W.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Brittle-Ductile Relaxation Kinetics of Strained AlGaN/GaN

The authors have directly measured the stress evolution during metal organic chemical vapor deposition of AlGaN/GaN heterostructures on sapphire. In situ stress measurements were correlated with ex situ microstructural analysis to directly determine a critical thickness for cracking and the subsequent relaxation kinetics of tensile-strained Al{sub x}Ga{sub 1{minus}x}N on GaN. Cracks appear to initiate the formation of misfit dislocations at the AlGaN/GaN interface, which account for the majorit… more

Date: October 5, 1999

Creator: CHASON, E.; FLORO, JERROLD A.; FOLLSTAEDT, DAVID M.; HAN, JUNG; HEARNE, SEAN JOSEPH; LEE, STEPHEN R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department