Evidence for Cooperative Oxidation of Mocvd Precursors Used in BaxSr1‐x TiO3 Film Growth

1996 ◽  
Vol 446 ◽  
Author(s):  
Timothy E. Glassman ◽  
Gautam Bhandari ◽  
Thomas H. Baum
Keyword(s):  
Thermal Decomposition ◽  
Film Growth ◽  
Oxidation Mechanism ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Precise Control ◽  
Carbonate Formation ◽  
Diffraction Patterns ◽  
High Dielectric

AbstractMetal ß‐diketonate complexes are common precursors for chemical vapor deposition (CVD) of a wide variety of thin‐film materials. Liquid delivery CVD has been used to deposit high dielectric constant materials, such as BaxSr1‐xTiO3.[1] This method relies upon volumetric metering of organic soluble precursors, “flash” vaporization to transport the reactants into the gas‐phase and subsequent thermal decomposition onto the heated substrate. This approach enables the precise control of deposited film stoichiometry. In this study, simultaneous thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to examine the transport and thermal decomposition properties of M(thd)2 (M = Sr, Ba) and Ti(O‐i‐Pr)2(thd)2. In an argon atmosphere, vaporization and transport are observed below 400 °C. In oxidizing atmospheres, such as nitrous oxide and oxygen, decomposition leads to metal carbonate formation as evidenced by both the mass balance and x‐ray diffraction patterns of the residual solids. In the presence of an equimolar amount of the Ti precursor, the formation of carbonates is not observed and oxides are produced at greatly reduced temperatures. Based upon this data, a cooperative oxidation mechanism is proposed which results in “clean” precursor decomposition and BST oxide formation at temperatures near 500 °C.

scholarly journals A Facile Method to Construct MXene/CuO Nanocomposite with Enhanced Catalytic Activity of CuO on Thermal Decomposition of Ammonium Perchlorate

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2457 ◽  
Author(s):  
Haifeng Zhao ◽  
Jing Lv ◽  
Junshan Sang ◽  
Li Zhu ◽  
Peng Zheng ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Catalytic Activity ◽  
Ammonium Perchlorate ◽  
Photoelectron Spectra ◽  
Gravimetric Analysis ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Improved Performance ◽  
Calcination Method

In this work, a mixing-calcination method was developed to facilely construct MXene/CuO nanocomposite. CuO and MXene were first dispersed in ethanol with sufficient mixing. After solvent evaporation, the dried mixture was calcinated under argon to produce a MXene/CuO nanocomposite. As characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectra (XPS), CuO nanoparticles (60–100 nm) were uniformly distributed on the surface and edge of MXene nanosheets. Furthermore, as evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA), the high-temperature decomposition (HTD) temperature decrease of ammonium perchlorate (AP) upon addition of 1 wt% CuO (hybridized with 1 wt% MXene) was comparable with that of 2 wt% CuO alone, suggesting an enhanced catalytic activity of CuO on thermal decomposition of AP upon hybridization with MXene nanosheets. This strategy could be further applied to construct other MXene/transition metal oxide (MXene/TMO) composites with improved performance for various applications.

Preparation by solution mixing and characterization of condensation type poly(dimethyl siloxane)/graphene nanoplatelets composites

2021 ◽  
pp. 002199832110558
Author(s):  
Panayiotis Ketikis ◽  
Efthimios Damopoulos ◽  
Georgios Pilatos ◽  
Panagiotis Klonos ◽  
Apostolos Kyritsis ◽  
...  
Keyword(s):  
Graphene Nanoplatelets ◽  
Matrix Composites ◽  
Dielectric Relaxation Spectroscopy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Melting Temperatures ◽  
Dimethyl Siloxane ◽  
Diffraction Patterns ◽  
The Impact

The impact of the incorporation of graphene nanoplatelets (GN) on the properties of hydroxyl-terminated poly(dimethylsiloxane) (PDMS) matrices was investigated. The composites were prepared by solution mixing, using tetrahydrofuran (THF) as a solvent. Brookfield viscosimetry, implemented during the vulcanization process, revealed that GN increases the viscosity of the system, compared to pristine PDMS, proportionally to its concentration. X-ray diffraction patterns suggested an efficient dispersion of GN in the polysiloxane matrix. The D and G bands ratio (ID/IG) calculation, based on RAMAN spectra of GN/PDMS specimens, revealed more defects in graphene nanoplatelets when incorporated in the PDMS matrix. By differential scanning calorimetry (DSC), a marginal increase in crystallization, glass transition and melting temperatures of PDMS in GN/PDMS composites was observed. Improvement of the thermal stability of LMW PDMS composites, especially for higher GN concentrations (3 and 5 phr), was noticed by thermogravimetric analysis (TGA). Additionally, GN enhanced the tensile strength of composites, up to 73% for the 3 phr GN/LMW PDMS composite. A significant increase in the elongation at break was recorded, whereas no effect on the modulus of elasticity was recorded. The decrease in toluene-swelling, for the LMW PDMS matrix composites, was attributed to the increase in the tortuosity path because of the efficient dispersion of GN. A decrease in oxygen permeability of 55–65% and 44–58% was measured in membranes made of PDMS composites containing 0.5 phr and 1 phr GN, respectively. Dielectric relaxation spectroscopy (DRS) measurements recorded a significant increase in the conductivity of the higher graphene content composites.

Structure and properties of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate)/poly(L-lactic acid) quasi core/sheath melt-electrospun microfibers

2018 ◽  
Vol 89 (9) ◽  
pp. 1770-1781 ◽  
Author(s):  
Huaizhong Xu ◽  
Benedict Bauer ◽  
Masaki Yamamoto ◽  
Hideki Yamane
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Lactic Acid ◽  
Tensile Tests ◽  
Processing Parameters ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffraction Patterns

A facile route was proposed to fabricate core–sheath microfibers, and the relationships among processing parameters, crystalline structures and the mechanical properties were investigated. The compression molded poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/poly(L-lactic acid) (PLLA) strip enhanced the spinnability of PHBH and the mechanical properties of PLLA as well. The core–sheath ratio of the fibers was determined by the prefab strip, while the PLLA sheath component did not completely cover the PHBH core component due to the weak interfacial tension between the melts of PHBH and PLLA. A rotational target was applied to collect aligned fibers, which were further drawn in a water bath. The tensile strength and the modulus of as-spun and drawn fibers increased with increasing the take-up velocities. When the take-up velocity was above 500 m/min, the jet became unstable and started to break up at the tip of the Taylor cone, decreasing the mechanical properties of the fibers. The drawing process facilitated the crystallization of PLLA and PHBH, and the tensile strength and the modulus increased linearly with the increasing the draw ratio. The crystal information displayed from wide-angle X-ray diffraction patterns and differential scanning calorimetry heating curves supported the results of the tensile tests.

Investigation of Thin Film Growth of B12As2 by Chemical Vapor Deposition

2003 ◽  
Vol 764 ◽  
Author(s):  
R. Nagarajan ◽  
J.H. Edgar ◽  
J. Pomeroy ◽  
M. Kuball ◽  
T. Aselage
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Film Growth ◽  
Chemical Vapor ◽  
Thin Film Growth ◽  
X Ray Diffraction ◽  
Flow Rates ◽  
X Ray ◽  
Effects Of Temperature ◽  
Reactant Flow

AbstractThe chemical vapor deposition of icosahedral boron arsenide, B12As2, on 6H-SiC (0001) (on and off-axis) substrates was studied using hydrides as the reactants. The effects of temperature and reactant flow rates on the phases deposited and the crystal quality were determined. The growth rate increased with temperature from 1.5μm/h at 1100°C to 5 μm/h at 1400°C and decreased thereafter. X-ray diffraction revealed that the deposits were amorphous when the deposition temperature is below 1150° C. Above 1150°C, smooth B12As2 films were formed on 6H-SiC substrates with an orientation of (0001) B12As2 parallel to 6H-SiC (0001). Raman spectroscopy confirmed the strongly c-axis oriented nature of B12As2 film on 6H-SiC.

scholarly journals The Effect of Nanosizing on the Oxidation of Partially Oxidized Copper Nanoparticles

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2878
Author(s):  
Jindřich Leitner ◽  
David Sedmidubský ◽  
Michal Lojka ◽  
Ondřej Jankovský
Keyword(s):  
Copper Nanoparticles ◽  
Scanning Transmission Electron Microscopy ◽  
Oxidation Mechanism ◽  
Oxidation Reactions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Final State ◽  
Micro Particles ◽  
Transmission Electron ◽  
Scanning Transmission

Copper nanoparticles are of great interest in various applications, such as catalysis, cooling fluids, conductive inks or for their antibacterial activity. In this paper, the thermal behavior of copper nanoparticles was studied using thermogravimetry, differential thermal analysis and differential scanning calorimetry. Original Cu samples as well as the products of oxidation were analysed by X-ray diffraction, scanning/transmission electron microscopy and energy dispersive spectroscopy. A step-by-step oxidation mechanism during the oxidation of Cu nano-powders was observed. The Cu-nano oxidation starts slightly above 150 °C when bulk copper does not yet react. The dominant oxidation product in the first step is Cu2O while CuO was identified as the final state of oxidation. Our results confirm an easier oxidation process of Cu-nano than Cu-micro particles, which must be attributed to kinetic not thermodynamic aspects of oxidation reactions.

New crystal structures in the realm of 5,5′-azotetrazolates

2015 ◽  
Vol 70 (2) ◽  
pp. 125-134 ◽  
Author(s):  
Martin Lampl ◽  
Gerhard Laus ◽  
Doris E. Braun ◽  
Volker Kahlenberg ◽  
Klaus Wurst ◽  
...  
Keyword(s):  
Differential Scanning Calorimetry ◽  
Single Crystal ◽  
Crystal Structures ◽  
Organic Cations ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffraction Patterns

AbstractThe preparation of six new 5,5′-azotetrazolates with organic cations is reported. Differential scanning calorimetry of all compounds showed exothermic decompositions. The crystal structures of the six 5,5′-azotetrazolates were determined by single-crystal X-ray diffraction analyses. The phase purities of the bulk samples were confirmed by Pawley fits of the experimental and calculated powder X-ray diffraction patterns.

Electronic Excitation-Induced Surface Chemistry and Electron-Beam-Assisted Chemical Vapor Deposition

1989 ◽  
Vol 158 ◽  
Author(s):  
F. Bozso ◽  
Ph. Avouris
Keyword(s):  
Electron Beam ◽  
Film Growth ◽  
Molecular Layer ◽  
Chemical Vapor ◽  
Electronic Excitations ◽  
Precise Control ◽  
Selective Area ◽  
Low Energy Electron ◽  
Nitride Oxide ◽  
Molecular Layers

ABSTRACTSelective area deposition of thin films and surface structures with precise control over their composition is possible in UHV by using low energy electron beams to induce electronic excitations in adsorbed molecular layers. Upon electron impact, adsorbed/co-adsorbed molecules decompose into reactive species, resulting in film growth. The composition of the film reflects that of the adsorbed molecular layer, which at cryogenic temperatures can sensitively be controlled by the partial pressure of the reactant gases. We present results of detailed studies of adsorption, thermal and electron-beam-induced dissociation of disilane and ammonia on silicon. We show that by proper choice of temperature, gas phase composition and electron beam, amorphous silicon, silicon nitride, oxide, silicon oxinitride films can be grown with nearly monolayer thickness resolution.

Manufacture of Ternary Solid Dispersions Composed of Nifedipine, Eudragit® E and Adsorbent

2011 ◽  
Vol 317-319 ◽  
pp. 185-188 ◽  
Author(s):  
Pornsak Sriamornsak ◽  
Srisuda Kontong ◽  
Yotsanan Weerapol ◽  
Jurairat Nunthanid ◽  
Srisagul Sungthongjeen ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Solid Dispersions ◽  
Ternary Systems ◽  
Dissolution Enhancement ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Ternary Solid Dispersions ◽  
Diffraction Patterns ◽  
Physical Mixtures

The aim of this study was to manufacture the ternary solid dispersions composed of nifedipine, Eudragit® E and adsorbent. Dissolution enhancement of nifedipine was also investigated. The inert solid carriers were added in the mixtures of nifedipine and Eudragit® E at varying ratios. The physicochemical properties of ternary systems, compared to physical mixtures, were analyzed using powder x-ray diffraction (PXRD) and differential scanning calorimetry (DSC). The dissolution of nifedipine from ternary systems was compared to the drug alone. The influence of drug:polymer: adsorbent ratio and type of adsorbent on the dissolution rate of the drug was also evaluated. The PXRD and DSC results of the systems with high amount of polymer showed that the drug was present in an amorphous form. On the other hand, the diffraction patterns and DSC thermograms of the physical mixtures revealed that to some extent the drug was present in a crystalline form. The results from this study demonstrated that an improvement in dissolution rate of nifedipine with Eudragit® E and adsorbents was obtained.

The Microstructure of Fe7C3 Formed at 300°C by Plasma Enhanced Chemical Vapor Deposition (PECVD)

1993 ◽  
Vol 313 ◽  
Author(s):  
H. Siriwardane ◽  
P. Fraundorf ◽  
J.W. Newkirk ◽  
O.A. Pringle ◽  
W.J. James
Keyword(s):  
Oxidation Process ◽  
Iron Carbide ◽  
Chemical Vapor ◽  
Carbon Films ◽  
Corrosion And Wear ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Iron Phase ◽  
Diffraction Patterns

Thin iron carbide films were prepared by introducing iron penta carbonyl (FeCO5) and hydrogen (H2) into a glow discharge. The films are of potential interest in corrosion and wear resistant applications. X-ray diffraction data of films (≈ 7000 Å thick) deposited on glass at 300°C evidenced only Fe7C3. Thinner films were required for examination by analytical and high resolution transmission electron Microscopy. Therefore, two sets of films (“thin” < 200 Å and “thick” ≈ 800 Å) were plasma-deposited on carbon or holey carbon films supported on copper grids. The thin TEM specimens exhibited a fine texture and gave rise to ring diffraction patterns, whereas the thick TEM specimens evidenced two types of structure: (i) half-Micron sized grains separated from one another by 1–2 Microns on the support, although sometimes interconnected by single crystal platelets and (ii) 300 Å grapelike clumps of 100–200 Å crystals, each individually surrounded by a 50 Å non-crystalline coating. The latter structure may result from a post-formation oxidation process which expels carbon from the iron phase into grain boundaries.

Nanostructured Silicon thin films Deposited by PECVD in the Presence of Silicon Nanoparticles

1997 ◽  
Vol 467 ◽  
Author(s):  
G. Viera ◽  
P. Roca i Cabarrocas ◽  
S. Hamma ◽  
S. N. Sharma ◽  
J. Costa ◽  
...  
Keyword(s):  
Thin Films ◽  
Silicon Nanoparticles ◽  
Film Growth ◽  
Electrical Characterization ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
Silicon Matrix ◽  
Silicon Thin Films ◽  
Nanostructured Silicon ◽  
Transmission Electron

ABSTRACTNanostructured silicon thin films have been deposited by plasma enhanced chemical vapor deposition at low substrate temperature (100 °C) in the presence of silicon nanoparticles. The nanostructure of the films was revealed by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which showed ordered silicon domains (1–2 nm) embedded in an amorphous silicon matrix. These ordered domains are due to the particles created in the discharge that contribute to the film growth. One consequence of the incorporation of nanoparticles is the accelerated crystallization of the nanostructured silicon thin films when compared to standard a-Si:H, as shown by the electrical characterization during the annealing.

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