TY - JOUR
TI - FIB Sample Preparation for In Depth EDS Analysis
AU - Garcia, Roberto
AU - Stevie, Fred A.
AU - Giannuzzi, Lucille
T2 - Microscopy and Microanalysis
DA - 2019/8/5/
PY - 2019/8/5/
DO - 10.1017/s1431927619005300
VL - 25
IS - S2
SP - 914-915
ER -
TY - JOUR
TI - Sedimentary record from Patagonia, southern Chile supports cosmic-impact triggering of biomass burning, climate change, and megafaunal extinctions at 12.8 ka
AU - Pino, Mario
AU - Abarzua, Ana M.
AU - Astorga, Giselle
AU - Martel-Cea, Alejandra
AU - Cossio-Montecinos, Nathalie
AU - Navarro, R. Ximena
AU - Lira, Maria Paz
AU - Labarca, Rafael
AU - LeCompte, Malcolm A.
AU - Adedeji, Victor
AU - Moore, Christopher R.
AU - Bunch, Ted E.
AU - Mooney, Charles
AU - Wolbach, Wendy S.
AU - West, Allen
AU - Kennett, James P.
T2 - SCIENTIFIC REPORTS
AB - Abstract The Younger Dryas (YD) impact hypothesis posits that fragments of a large, disintegrating asteroid/comet struck North America, South America, Europe, and western Asia ~12,800 years ago. Multiple airbursts/impacts produced the YD boundary layer (YDB), depositing peak concentrations of platinum, high-temperature spherules, meltglass, and nanodiamonds, forming an isochronous datum at >50 sites across ~50 million km² of Earth’s surface. This proposed event triggered extensive biomass burning, brief impact winter, YD climate change, and contributed to extinctions of late Pleistocene megafauna. In the most extensive investigation south of the equator, we report on a ~12,800-year-old sequence at Pilauco, Chile (~40°S), that exhibits peak YD boundary concentrations of platinum, gold, high-temperature iron- and chromium-rich spherules, and native iron particles rarely found in nature. A major peak in charcoal abundance marks an intense biomass-burning episode, synchronous with dramatic changes in vegetation, including a high-disturbance regime, seasonality in precipitation, and warmer conditions. This is anti-phased with northern-hemispheric cooling at the YD onset, whose rapidity suggests atmospheric linkage. The sudden disappearance of megafaunal remains and dung fungi in the YDB layer at Pilauco correlates with megafaunal extinctions across the Americas. The Pilauco record appears consistent with YDB impact evidence found at sites on four continents.
DA - 2019/3/13/
PY - 2019/3/13/
DO - 10.1038/s41598-018-38089-y
VL - 9
SP -
SN - 2045-2322
ER -
TY - JOUR
TI - Origin of Ferroelectric Phase in Undoped HfO2 Films Deposited by Sputtering
AU - Mittmann, Terence
AU - Materano, Monica
AU - Lomenzo, Patrick D.
AU - Park, Min Hyuk
AU - Stolichnov, Igor
AU - Cavalieri, Matteo
AU - Zhou, Chuanzhen
AU - Chung, Ching-Chang
AU - Jones, Jacob L.
AU - Szyjka, Thomas
AU - Mueller, Martina
AU - Kersch, Alfred
AU - Mikolajick, Thomas
AU - Schroeder, Uwe
T2 - ADVANCED MATERIALS INTERFACES
AB - Abstract Thin film metal–insulator–metal capacitors with undoped HfO 2 as the insulator are fabricated by sputtering from ceramic targets and subsequently annealed. The influence of film thickness and annealing temperature is characterized by electrical and structural methods. After annealing, the films show distinct ferroelectric properties. Grazing incidence X‐ray diffraction measurements reveal a dominant ferroelectric orthorhombic phase for thicknesses in the 10–50 nm range and a negligible non‐ferroelectric monoclinic phase fraction. Sputtering HfO 2 with additional oxygen during the deposition decreases the remanent polarization. Overall, the impact of oxygen vacancies and interstitials in the HfO 2 film during deposition and annealing is correlated to the phase formation process.
DA - 2019/6//
PY - 2019/6//
DO - 10.1002/admi.201900042
VL - 6
IS - 11
SP -
SN - 2196-7350
KW - ferroelectricity
KW - hafnia
KW - orthorhombic phase
KW - oxygen vacancies
KW - sputtering
ER -
TY - JOUR
TI - Electron backscatter diffraction of Nb3Sn coated niobium: Revealing structure as a function of depth
AU - Tuggle, Jay
AU - Pudasaini, Uttar
AU - Angle, Jonathan
AU - Eremeev, Grigory
AU - Reece, Charlie E.
AU - Stevie, Fred A.
AU - Kelley, Michael J.
T2 - JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B
AB - Over the last two decades, advances in Electron Backscatter Diffraction (EBSD) have moved the technique from a research tool to an essential characterization technique in many fields of material research. EBSD is the best suited technique for determining structure as a function of depth. This characterization is critically important but has been previously absent from Nb3Sn efforts. While EBSD is the technique of choice, obtaining quality data can be difficult. Sample preparation in particular is nontrivial. Here, we summarize the general principles of EBSD, discuss specific sample preparation techniques for Nb3Sn coated SRF cavity materials, and give examples of how EBSD is being used to understand fundamental growth mechanisms for Nb3Sn coatings.
DA - 2019/9//
PY - 2019/9//
DO - 10.1116/1.5096338
VL - 37
IS - 5
SP -
SN - 2166-2746
ER -
TY - JOUR
TI - Low temperature cathodoluminescence study of Fe-doped beta-Ga2O3
AU - Hany, Ibrahim
AU - Yang, Ge
AU - Zhou, Chuanzhen Elaine
AU - Sun, Cheng
AU - Gundogdu, Kenan
AU - Seyitliyev, Dovletgeldi
AU - Danilov, Evgeny O.
AU - Castellano, Felix N.
AU - Sun, Dali
AU - Vetter, Eric
T2 - MATERIALS LETTERS
AB - Optical and electrical properties along the b-axis of Fe-doped β-Ga2O3 were studied using low temperature cathodoluminescence (CL) spectroscopy, optical absorption spectroscopy and current-voltage (IV) measurements. The optical absorption spectroscopy showed an absorption edge without near edge shoulder and the corresponding optical bandgap was calculated to be 4.45 eV using direct band gap treatment. The temperature dependent CL measurements exhibited a strong blue to ultraviolet (UV) band composed of multiple low intensity peaks in the blue range, a main blue peak, a main UV peak, and a weak UV band from the as-grown Fe-doped β-Ga2O3. After a controlled annealing in air, the emissions changed to a red to near infrared (R-NIR) band with two sharp peaks and an UV band that is resolved at room temperature to three UV broad peaks. The R-NIR sharp peaks from the air-annealed sample were ascribed to incorporation of nitrogen during air annealing.
DA - 2019/12/15/
PY - 2019/12/15/
DO - 10.1016/j.matlet.2019.126744
VL - 257
SP -
SN - 1873-4979
ER -
TY - JOUR
TI - Peroxisome Proliferator-activated Receptor-gamma Deficiency Exacerbates Fibrotic Response to Mycobacteria Peptide in Murine Sarcoidosis Model
AU - Malur, Anagha
AU - Mohan, Arjun
AU - Barrington, Robert A.
AU - Leffler, Nancy
AU - Malur, Amrita
AU - Muller-Borer, Barbara
AU - Murray, Gina
AU - Kew, Kim
AU - Zhou, Chuanzhen
AU - Russell, Josh
AU - Jones, Jacob L.
AU - Wingard, Christopher J.
AU - Barna, Barbara P.
AU - Thomassen, Mary Jane
T2 - AMERICAN JOURNAL OF RESPIRATORY CELL AND MOLECULAR BIOLOGY
AB - We established a murine model of multiwall carbon nanotube (MWCNT)-elicited chronic granulomatous disease that bears similarities to human sarcoidosis pathology, including alveolar macrophage deficiency of peroxisome proliferator-activated receptor γ (PPARγ). Because lymphocyte reactivity to mycobacterial antigens has been reported in sarcoidosis, we hypothesized that addition of mycobacterial ESAT-6 (early secreted antigenic target protein 6) to MWCNT might exacerbate pulmonary granulomatous pathology. MWCNTs with or without ESAT-6 peptide 14 were instilled by the oropharyngeal route into macrophage-specific PPARγ-knockout (KO) or wild-type mice. Control animals received PBS or ESAT-6. Lung tissues, BAL cells, and BAL fluid were evaluated 60 days after instillation. PPARγ-KO mice receiving MWCNT + ESAT-6 had increased granulomas and significantly elevated fibrosis (trichrome staining) compared with wild-type mice or PPARγ-KO mice that received only MWCNT. Immunostaining of lung tissues revealed elevated fibronectin and Siglec F expression on CD11c+ infiltrating alveolar macrophages in the presence of MWCNT + ESAT-6 compared with MWCNT alone. Analyses of BAL fluid proteins indicated increased levels of transforming growth factor (TGF)-β and the TGF-β pathway mediator IL-13 in PPARγ-KO mice that received MWCNT + ESAT-6 compared with wild-type or PPARγ-KO mice that received MWCNT. Similarly, mRNA levels of matrix metalloproteinase 9, another requisite factor for TGF-β production, was elevated in PPARγ-KO mice by MWCNT + ESAT-6. Analysis of ESAT-6 in lung tissues by mass spectrometry revealed ESAT-6 retention in lung tissues of PPARγ-KO but not wild-type mice. These data indicate that PPARγ deficiency promotes pulmonary ESAT-6 retention, exacerbates macrophage responses to MWCNT + ESAT-6, and intensifies pulmonary fibrosis. The present findings suggest that the model may facilitate understanding of the effects of environmental factors on sarcoidosis-associated pulmonary fibrosis.
DA - 2019/8//
PY - 2019/8//
DO - 10.1165/rcmb.2018-0346OC
VL - 61
IS - 2
SP - 198-208
SN - 1535-4989
KW - multiwall carbon nanotubes
KW - granuloma
KW - peroxisome proliferator-activated receptor-gamma fibrosis
KW - lung
KW - sarcoid
ER -
TY - JOUR
TI - Optical and electrical properties of all-inorganic Cs2AgBiBr6 double perovskite single crystals
AU - Zhang, Zheng
AU - Yang, Ge
AU - Zhou, Chuanzhen
AU - Chung, Ching-Chang
AU - Hany, Ibrahim
T2 - RSC ADVANCES
AB - Temperature-dependent resistivity and cathodoluminescence (CL) measurements of solution-processed Cs2AgBiBr6 double perovskite single crystals.
DA - 2019/8/4/
PY - 2019/8/4/
DO - 10.1039/c9ra04045e
VL - 9
IS - 41
SP - 23459-23464
SN - 2046-2069
ER -
TY - JOUR
TI - Effect of furnace annealing on the ferroelectricity of Hf0.5 Zr0.5O2 thin films
AU - Shekhawat, Aniruddh
AU - Walters, Glen
AU - Chung, Ching-Chang
AU - Garcia, Roberto
AU - Liu, Yang
AU - Jones, Jacob
AU - Nishida, Toshikazu
AU - Moghaddam, Saeed
T2 - THIN SOLID FILMS
AB - The effect of furnace annealing on the ferroelectricity and crystal phase of Hf0.5ZrO2 (HZO) ultrathin films is studied as a function of film thickness. HZO films are deposited using atomic layer deposition (ALD) in a Ge-HZO-TiN stack with Pt as the top contact electrode. Furnace annealing is carried out after crystallizing the films with rapid thermal annealing in the presence of a TiN capping electrode. While furnace annealing did not have much impact on the 108 ALD cycles (~11 nm) film, it enhanced the ferroelectricity of the 44 ALD cycles film (~4.5 nm). Positive-up-negative-down tests provide evidence of ferroelectricity in the 40 ALD cycles (~4 nm) furnace annealed film after cycling the film at higher fields. Grazing incidence X-ray diffraction shows that the non-centrosymmetric orthorhombic phase responsible for ferroelectricity increased after furnace annealing in thinner films, but little change occurred in the 108 ALD cycles film that was rich in orthorhombic phase prior to furnace annealing. An analysis of the HZO films with a tapping mode atomic force microscope shows grain growth in the 44, and 40 ALD cycles films after furnace annealing.
DA - 2019/5/1/
PY - 2019/5/1/
DO - 10.1016/j.tsf.2019.03.031
VL - 677
SP - 142-149
SN - 0040-6090
KW - Hafnium oxide
KW - Ultrathin films
KW - Remnant polarization
KW - Ferroelectric switching
KW - Furnace annealing
KW - Thickness dependence
ER -