scholarly journals A Thermodynamic Investigation of Ni on Thin-Film Titanates (ATiO3)

Inorganics ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 69
Author(s):  
Chao Lin ◽  
Alexandre C. Foucher ◽  
Eric A. Stach ◽  
Raymond J. Gorte
Keyword(s):  
Atomic Layer Deposition ◽  
Coulometric Titration ◽  
Equilibrium Constants ◽  
Atomic Layer ◽  
Co2 Reforming ◽  
Co2 Reforming Of Ch4 ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Ni Oxidation ◽  
Scanning Transmission

Thin, ~1-nm films of CaTiO3, SrTiO3, and BaTiO3 were deposited onto MgAl2O4 by Atomic Layer Deposition (ALD) and then studied as catalyst supports for ~5 wt % of Ni that was added to the perovskite thin films by Atomic Layer Deposition. Scanning Transmission Electron Microscopy demonstrated that both the Ni and the perovskites uniformly covered the surface of the support following oxidation at 1073 K, even after redox cycling, but large Ni particles formed following a reduction at 1073 K. When compared to Ni/MgAl2O4, the perovskite-containing catalysts required significantly higher temperatures for Ni reduction. Equilibrium constants for Ni oxidation, as determined from Coulometric Titration, indicated that the oxidation of Ni shifted to lower PO2 on the perovskite-containing materials. Based on Ni equilibrium constants, Ni interactions are strongest with CaTiO3, followed by SrTiO3 and BaTiO3. The shift in the equilibrium constant was shown to cause reversible deactivation of the Ni/CaTiO3/MgAl2O4 catalyst for CO2 reforming of CH4 at high CO2 pressures, due to the oxidation of the Ni.

scholarly journals Comparison of the Growth and Thermal Properties of Nonwoven Polymers after Atomic Layer Deposition and Vapor Phase Infiltration

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1028
Author(s):  
Laura Keskiväli ◽  
Pirjo Heikkilä ◽  
Eija Kenttä ◽  
Tommi Virtanen ◽  
Hille Rautkoski ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Electron Microscope ◽  
Atomic Layer Deposition ◽  
Atomic Layer ◽  
Scanning Transmission Electron Microscope ◽  
Scanning Calorimetry ◽  
Polymeric Surfaces ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Scanning Transmission

The growth mechanism of Atomic Layer Deposition (ALD) on polymeric surfaces differs from growth on inorganic solid substrates, such as silicon wafer or glass. In this paper, we report the growth experiments of Al2O3 and ZnO on nonwoven poly-L-lactic acid (PLLA), polyethersulphone (PES) and cellulose acetate (CA) fibres. Material growth in both ALD and infiltration mode was studied. The structures were examined with a scanning electron microscope (SEM), scanning transmission electron microscope (STEM), attenuated total reflectance-fourier-transform infrared spectroscopy (ATR-FTIR) and 27Al nuclear magnetic resonance (NMR). Furthermore, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were used to explore the effect of ALD deposition on the thermal properties of the CA polymer. According to the SEM, STEM and ATR-FTIR analysis, the growth of Al2O3 was more uniform than ZnO on each of the polymers studied. In addition, according to ATR-FTIR spectroscopy, the infiltration resulted in interactions between the polymers and the ALD precursors. Thermal analysis (TGA/DSC) revealed a slower depolymerization process and better thermal resistance upon heating both in ALD-coated and infiltrated fibres, more pronounced on the latter type of structures, as seen from smaller endothermic peaks on TA.

scholarly journals “Intelligent” Pt Catalysts Based on Thin LaCoO3 Films Prepared by Atomic Layer Deposition

Inorganics ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 113 ◽  
Author(s):  
Xinyu Mao ◽  
Alexandre C. Foucher ◽  
Eric A. Stach ◽  
Raymond J. Gorte
Keyword(s):  
Atomic Layer Deposition ◽  
Co Adsorption ◽  
Atomic Layer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Highly Active ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Scanning Transmission ◽  
Water Gas

LaCoO3 films were deposited onto MgAl2O4 powders by atomic layer deposition (ALD) and then used as catalyst supports for Pt. X-ray diffraction (XRD) showed that the 0.5 nm films exhibited a perovskite structure after redox cycling at 1073 K, and scanning transmission electron microscopy and elemental mapping via energy-dispersive X-ray spectroscopy (STEM/EDS) data demonstrated that the films covered the substrate uniformly. Catalysts prepared with 3 wt % Pt showed that the Pt remained well dispersed on the perovskite film, even after repeated oxidations and reductions at 1073 K. Despite the high Pt dispersion, CO adsorption at room temperature was negligible. Compared with conventional Pt on MgAl2O4, the reduced forms of the LaCoO3-containing catalyst were highly active for the CO oxidation and water gas shift (WGS) reactions, while the oxidized catalysts showed much lower activities. Surprisingly, the reduced catalysts were much less active than the oxidized catalysts for toluene hydrogen. Catalysts prepared from thin films of Co3O4 or La2O3 exhibited properties more similar to Pt/MgAl2O4. Possible reasons for how LaCoO3 affects properties are discussed.

scholarly journals Direct Epitaxial Nanometer-Thin InN of High Structural Quality on 4H-SiC by Atomic Layer Deposition

2020 ◽  
Author(s):  
Chih-Wei Hsu ◽  
Petro Deminskyi ◽  
Ivan Martinovic ◽  
Ivan G. Ivanov ◽  
Justinas Palisaitis ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Indium Nitride ◽  
Atomic Layer ◽  
Structural Quality ◽  
High Electron ◽  
X Ray Diffraction ◽  
High Quality ◽  
Subsequent Formation ◽  
Transmission Electron ◽  
Layer Deposition

<div>Indium nitride (InN) is a highly promising material for high frequency electronics given its</div><div>low band gap and high electron mobility. The development of InN-based devices is hampered</div><div>by the limitations in depositing very thin InN films of high quality. We demonstrate growth of</div><div>high-structural-quality nanometer thin InN films on 4H-SiC by atomic layer deposition (ALD).</div><div>High resolution X-ray diffraction and transmission electron microscopy show epitaxial growth</div><div>and an atomically sharp interface between InN and 4H-SiC. The InN film is fully relaxed already after a few atomic layers and shows a very smooth morphology where the low surface</div><div>roughness (0.14 nm) is found to reproduced sub-nanometer surface features of the substrate. Raman measurements show an asymmetric broadening caused by grains in the InN film. Our results show the potential of ALD to prepare high quality nanometer-thin InN films for subsequent formation of heterojunctions.</div>

scholarly journals Growth and characterization of CNT–TiO2 heterostructures

2014 ◽  
Vol 5 ◽  
pp. 946-955 ◽  
Author(s):  
Yucheng Zhang ◽  
Ivo Utke ◽  
Johann Michler ◽  
Gabriele Ilari ◽  
Marta D Rossell ◽  
...  
Keyword(s):  
Good Control ◽  
Atomic Layer ◽  
Oxide Material ◽  
Electronic Information ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Metal Metal ◽  
Scanning Transmission ◽  
Electron Energy Loss

A thriving field in nanotechnology is to develop synergetic functions of nanomaterials by taking full advantages of unique properties of each component. In this context, combining TiO2 nanocrystals and carbon nanotubes (CNTs) offers enhanced photosensitivity and improved photocatalytic efficiency, which is key to achieving sustainable energy and preventing environmental pollution. Hence, it has aroused a tremendous research interest. This report surveys recent research on the topic of synthesis and characterization of the CNT–TiO2 interface. In particular, atomic layer deposition (ALD) offers a good control of the size, crystallinity and morphology of TiO2 on CNTs. Analytical transmission electron microscopy (TEM) techniques such as electron energy loss spectroscopy (EELS) in scanning transmission mode provides structural, chemical and electronic information with an unprecedented spatial resolution and increasingly superior energy resolution, and hence is a necessary tool to characterize the CNT–TiO2 interface, as well as other technologically relevant CNT–metal/metal oxide material systems.

Microstructural evolution of ZrO2–HfO2 nanolaminate structures grown by atomic layer deposition

2004 ◽  
Vol 19 (2) ◽  
pp. 643-650 ◽  
Author(s):  
Hyoungsub Kim ◽  
Paul C. McIntyre ◽  
Krishna C. Saraswat
Keyword(s):  
Surface Roughness ◽  
Atomic Layer Deposition ◽  
Microstructural Evolution ◽  
Single Layer ◽  
Atomic Layer ◽  
Individual Layer ◽  
Force Microscopy ◽  
Layer Sequence ◽  
Transmission Electron ◽  
Layer Deposition

Zirconia–hafnia (ZrO2–HfO2) nanolaminate structures were grown using the atomic layer deposition (ALD) technique with different stacking sequences and layer thickness layer thicknesses. The microstructural evolution and surface roughness were compared with those of single-layer ZrO2 or HfO2 films using transmission electron microscopy and atomic force microscopy. Thin single-layer ALD-ZrO2 films were polycrystalline and composed of the tetragonal ZrO2 phase as-deposited, whereas thicker (>14 nm) films were composed mainly of the monoclinic phase. HfO2 films were amorphous as-deposited and crystallized into primarily monoclinic during subsequent anneals at temperatures over 500 °C. All the nanolaminate structures having individual layer thicknesses greater than approximately 2 nm were crystalline (mixture of tetragonal and monoclinic phases) independent of layer sequence and also exhibited a layer-to-layer epitaxy relationship within each grain. However, the identity of the starting layer determined the final grain size and surface roughness of the nanolaminates. A qualitative model for the observed microstructure evolution of the laminate films is proposed.

Atomic Layer Deposition on Quantities of Multiwalled Carbon Nanotubes

2007 ◽  
Vol 1054 ◽  
Author(s):  
Andrew S. Cavanagh ◽  
Christopher A. Wilson ◽  
Alan W. Weimer ◽  
Steven M. George
Keyword(s):  
Carbon Nanotubes ◽  
Atomic Layer Deposition ◽  
Multiwalled Carbon Nanotubes ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Layer ◽  
Multiwalled Carbon ◽  
Transmission Electron ◽  
Layer Deposition

ABSTRACTAtomic layer deposition (ALD) was performed on quantities of multiwalled carbon nanotubes (MWCNTs) in a rotary reactor. Because of nucleation difficulties, Al2O3 ALD grew as nanospheres on the MWCNTs. After a NO2 nucleation treatment, Al2O3 ALD films grew conformally and noncovalently functionalized the surface of the MWCNT. This Al2O3 ALD film served as a platform for the growth of W ALD metal. The uncoated and ALD-coated MWCNTs were characterized with transmission electron microscopy and x-ray photoelectron spectroscopy. This study demonstrates that ALD can be performed on quantities of very high surface area MWCNT substrates.

AlGaN/GaN multiple quantum wells grown by using atomic layer deposition technique

2008 ◽  
Vol 1068 ◽  
Author(s):  
Ming-Hua Lo ◽  
Zhen-Yu Li ◽  
Shih-Wei Chen ◽  
Jhih-Cang Hong ◽  
Ting-Chang Lu ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Quantum Wells ◽  
Atomic Layer ◽  
Atomic Force Microscope Image ◽  
Multiple Quantum Wells ◽  
Multiple Quantum ◽  
X Ray Diffraction ◽  
Atomic Force ◽  
Transmission Electron ◽  
Layer Deposition

ABSTRACTIn this work, we report on the growth of ultraviolet (UV) AlGaN/GaN multiple quantum wells (MQWs) structure using atomic layer deposition (ALD) technique. The AlGaN/GaN MQW sample grown on the sapphire substrate consisted of three GaN QWs and four AlGaN barriers comprised AlN/GaN superlattices (SLs). The root-mean-square value of the surface morphology was only 0.35 nm observed from the atomic force microscope image and no crack was found on the surface. Both of the high resolution X-ray diffraction curves and transmission electron microscope images showed sharp interfaces between SLs layers and QWs with good periodicity. These results demonstrate that the ALD could be a very useful technique for controlling the crystalline quality and thickness of the III-nitride epilayer.

Ti Coating of Nanocrystalline Diamond by Atomic Layer Deposition

2006 ◽  
Vol 304-305 ◽  
pp. 48-51 ◽  
Author(s):  
Jian Bing Zang ◽  
Jing Lu ◽  
Yan Hui Wang ◽  
X.H. Qi ◽  
Yun Gang Yuan
Keyword(s):  
Atomic Layer Deposition ◽  
Polycrystalline Diamond ◽  
High Strength ◽  
Atomic Layer ◽  
Nanocrystalline Diamond ◽  
X Ray Diffraction ◽  
Diamond Surfaces ◽  
Transmission Electron ◽  
Layer Deposition ◽  
Binary Reaction

Nanocrystalline diamond compact possesses not only the advantageous performance of polycrystalline diamond but also the high strength and the high toughness of nano-ceramics. However, single-phase nanocrystalline diamond compact is very difficult to sinter because of a huge amount of oxygen-containing and nitrogen-containing functional groups absorbed on the surface of nanocrystalline diamond. In this paper, atomic layer deposition (ALD) method has been used to coat nanocrystalline diamond with titanium, which will promote the bonding of nanocrystalline diamond as the bond in polycrystalline diamond. In vacuum, the H2 and TiCl4 reactants were employed alternately in an ABAB… binary reaction sequence to achieve Ti layer, which reacted with diamond matrix and formed TiC in the coating, realizing strong chemical bonding between the coating and the diamond. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were utilized to study the structure and the morphology of the coating. The results confirmed the formation of titanium carbide at the depositing temperature 500°C. The darker spots and strips observed on nanocrystalline diamond particles by TEM were proved to be TiC and the nucleation and subsequent growth of TiC preferentially occurred in the defects as twin zones and dislocation areas on diamond surfaces.

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