Preparation and Characterization of High-Surface-Area Aluminum Nitride Thin Films

1996 ◽  
Vol 454 ◽  
Author(s):  
S. A. Monie ◽  
C. G. Pantano
Keyword(s):  
Heat Treatment ◽  
Aluminum Nitride ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
Magic Angle Spinning ◽  
Treatment Temperature ◽  
Magic Angle ◽  
Free Standing ◽  
X Ray ◽  
Alumina Sol

ABSTRACTFree-standing aluminum nitride (AlN) films were prepared by ammonia heat-treatment of pseudoboehmite [AIO(OH)] gels derived from an alumina sol. Supported films on sapphire substrates were also made by spin-coating the alumina sol, followed by ammonia nitridation. The conversion of the specimens to AIN as a function of heat-treatment temperature was studied using various characterization techniques.For the free-standing films, X-ray diffraction (XRD) showed that upon ammonia treatment, the specimens were first transformed from pseudoboehmite to η-alumina and finally to A1N above 1000°C. 27Al magic-angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy confirmed the appearance of Al[N]4 coordination at 1000°C, indicative of AlN. Complete conversion to AlN was achieved after 5 hour nitridation at 1200°C. The 1200°C heat-treated films consisted of crystallites of AlN in the size range 0.01 − 0.15 μm, with pores between 0.03 − 0.25 μm in diameter, as observed by TEM/electron diffraction analyses. These films had BET surface areas of approximately 25 m2/g. Nitridation of the supported films to AlN occurred at lower temperatures (∼900°C), as shown by secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS).

scholarly journals Heat-Induced Discoloration of Chromophore Structures in Eucalyptus Lignin

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1686 ◽  
Author(s):  
Peng Zhang ◽  
Yanxia Wei ◽  
Yang Liu ◽  
Jianmin Gao ◽  
Yao Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photoelectron Spectroscopy ◽  
Eucalyptus Grandis ◽  
Gel Permeation Chromatography ◽  
Magic Angle Spinning ◽  
Saturated Steam ◽  
Magic Angle ◽  
13C Cpmas Nmr ◽  
Eucalyptus Wood ◽  
Dehydration Reactions

The color changes corresponding to chromophore structures in lignin caused by exposure of Eucalyptus (Eucalyptus grandis and E. urophylla) to heat were investigated. Eucalyptus wood powders were heat treated under saturated steam atmospheres for 10 h at 110 °C, 130 °C and 150 °C. The lignin was isolated before and after heat treatment. The physicochemical properties of the lignin and changes in chromophore structures during heat treatment was evaluated through wet chemical analysis, Fourier transform infrared spectroscopy (FTIR), diffuse reflectance ultraviolet-visible spectroscopy (DRUV-Vis), gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS) and 13C Cross polarization magic angle spinning nuclear magnetic resonance (13C CPMAS NMR). Wood color darkened and reddened with the increase in pressure and temperature. Depolymerization and dehydration reactions occurred via demethoxylation with heat treatment in saturated steam at 110 °C or 130 °C. Lignin condensed to form insoluble compounds after heat treatment in saturated steam at 150 °C. G units increased and S units decreased through demethylation during heat treatment, as revealed by FTIR and 13C-NMR analysis.

Improved Photocatalytic Activity of Copper Heterostructure Composites (Cu–Cu2O–CuO/AC) Prepared by Simple Carbothermal Reduction

2014 ◽  
Vol 67 (5) ◽  
pp. 749 ◽  
Author(s):  
Hongchao Ma ◽  
Yifeng Liu ◽  
Yinghuan Fu ◽  
Chunling Yu ◽  
Xiaoli Dong ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Activated Carbon ◽  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Carbothermal Reduction ◽  
Treatment Time ◽  
Carbon Support ◽  
Treatment Temperature ◽  
X Ray

Cu–Cu2O–CuO/activated carbon heterostructure composites with visible-light activity have been successfully synthesized by a simple carbothermal reduction procedure using CuSO4 as a single precursor. The resultant samples were characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements. The results showed that the Cu–Cu2O–CuO composites with size less than 10 nm dispersed well on the surface of activated carbon. Activated carbon played both a reducing agent and support role in the formation of Cu–Cu2O–CuO/activated carbon heterostructure composites. X-ray photoelectron spectroscopy analysis suggests that the outside of the nanoparticles is CuO and the inside of the nanoparticles is Cu metal and Cu2O. Moreover, the composition of Cu–Cu2O–CuO/activated carbon composites can be tailored by varying the Cu loading, heat-treatment temperature, and heat-treatment time. The photocatalytic activities of the catalysts were investigated by degrading reactive brilliant blue KN-R under visible-light irradiation. The Cu–Cu2O–CuO/activated carbon heterostructure composites showed excellent photocatalytic activity compared with other catalysts (pure CuO, Cu2O, Cu2O/activated carbon, CuO/activated carbon, and Cu2O–CuO/activated carbon), which is ascribed to synergistic action between the activated carbon support and photoactive copper species, and the presence of interfacial structures such as a Cu2O/CuO heterostructure, Cu/Cu2O (or CuO) Schottky barrier, and Cu2O/Cu/CuO ohmic heterojunction.

scholarly journals Comprehension of paraquat adsorption on faujasite zeolite X and Y in sodium form

2017 ◽  
Vol 36 (1-2) ◽  
pp. 684-693 ◽  
Author(s):  
Wina Rongchapo ◽  
Chalermpan Keawkumay ◽  
Nattawut Osakoo ◽  
Krittanun Deekamwong ◽  
Narong Chanlek ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Photoelectron Spectroscopy ◽  
Fourier Transform Infrared ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Zeolite X ◽  
X Ray

The nature of paraquat adsorption is compared between zeolite NaX and NaY which have the same faujasite structure but different Si/Al ratio, namely 1.2 and 2.2, respectively. The adsorption was proposed to occur via ion exchange and expected to increase with Al content. However, NaX had a lower paraquat adsorption capacity than NaY. The bare and paraquat-containing zeolites (PQX and PQY) were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, N2 adsorption–desorption analysis, magic-angle spinning nuclear magnetic resonance (MAS) NMR, and X-ray photoelectron spectroscopy. The presence of adsorbed paraquat was confirmed by Fourier transform infrared spectroscopy. Paraquat adsorbed in supercages of the zeolites resulting in a decrease of surface area and displacement of sodium cations. Results from 23Na MAS NMR and X-ray photoelectron spectroscopy indicated that interaction of sodium ions in the cavity of NaX was stronger than that in NaY, making it less exchangeable with paraquat.

Structure and Mechanical Properties of Unheated Chromium Aluminum Nitride Coatings Sputter-Deposited with Various Aluminum Content

2019 ◽  
Vol 824 ◽  
pp. 254-259
Author(s):  
Chirawat Chantharangsi ◽  
Chutima Paksunchai ◽  
Chutima Oopathump ◽  
Surasing Chaiyakun ◽  
Pattanaphong Janphuang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Aluminum Nitride ◽  
Photoelectron Spectroscopy ◽  
High Surface ◽  
Film Deposition ◽  
Diffraction Field ◽  
X Ray ◽  
Wear Rates ◽  
Al Content

Chromium aluminum nitride (CrAlN) has been extensively studied because of high hardness, high oxidation and corrosion resistance, and good wear resistance. However, utilizing substrate treatments such as heating and voltage biasing during film deposition usually leads to relatively high surface roughness that affects wear rates. It has been found that sputter deposition at low substrate temperatures can produce nano-grain coatings with enhanced structure and mechanical properties. For this reason, the CrAlN in this study was prepared by a reactive co-sputtering technique without the substrate treatments. Effects of Al content on structure and mechanical properties were investigated by X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectrometry, atomic force microscopy, X-ray photoelectron spectroscopy, and nanoindentation. The results suggest that these CrAlN films formed as solid solutions by substitution of Al for Cr in the CrN crystalline structure. The deposition with increasing Al but fixed N leads to N deficiency, therefore at high Al content these films form under 1:1 stoichiometric nitride. This lowers film crystallinity and hence refined film morphology. Surface roughness and hardness of the films decreased from 5.737 to 1.135 nm and from 31.69 to 26.56 GPa, respectively. However, the solid solution strengthening arising from the further increase of the Al content causes these values to rebound to 2.466 nm and to 30.16 GPa.

scholarly journals B2O3-Doped LATP Glass-Ceramics Studied by X-ray Diffractometry and MAS NMR Spectroscopy Methods

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 390
Author(s):  
Wioleta Ślubowska ◽  
Lionel Montagne ◽  
Olivier Lafon ◽  
François Méar ◽  
Konrad Kwatek
Keyword(s):  
Heat Treatment ◽  
Glass Ceramics ◽  
Lithium Ion ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Nmr Studies ◽  
X Ray ◽  
Glass Forming ◽  
The Impact

Two families of glasses in the Li2O-Al2O3-B2O3-TiO2-P2O5 system were prepared via two different synthesis routes: melt-quenching and ball-milling. Subsequently, they were submitted to crystallization and yielded the Li1.3Al0.3Ti1.7(PO4)3 (LATP)-based glass-ceramics. Glasses and corresponding glass-ceramics were studied by complementary X-ray diffraction (XRD) and 27Al, 31P, 7Li, 11B magic-angle spinning nuclear magnetic resonance (MAS NMR) methods in order to compare their structure and phase composition and elucidate the impact of boron additive on their glass-forming properties and crystallization process. XRD studies show that the addition of B2O3 improves the glass-forming properties of glasses prepared by either method and inhibits the precipitation of unwanted phases during heat treatment. MAS NMR studies allowed us to distinguish two LATP phases of slightly different chemical composition suggesting that LATP grains might not be homogeneous. In conclusion, the crystallization of boron-incorporated LATP glasses can is an effective way of obtaining LATP-based solid state electrolytes for the next generation of lithium-ion batteries provided the proper heat-treatment conditions are chosen.

Effect of Low-Temperature Heat Treatment on PM2.5 Adsorption Properties of GO Films

NANO ◽  
2019 ◽  
Vol 14 (12) ◽  
pp. 1950151
Author(s):  
Weiwu Zou ◽  
Baoshan Gu ◽  
Shiqing Sun ◽  
Shidong Wang ◽  
Xin Li ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Photoelectron Spectroscopy ◽  
Heat Treatment Temperature ◽  
Removal Rate ◽  
Treatment Temperature ◽  
Air Purification ◽  
Vacuum Heat Treatment ◽  
X Ray ◽  
Composition And Structure ◽  
Atmospheric Heat

To explore the mechanism of GO acting on PM[Formula: see text], a graphene oxide (GO) film was prepared via a spraying method for air purification. The effects of different media, temperature and heat treatment times on the adsorption of PM[Formula: see text] on GO film were investigated. The morphology, composition and structure of GO materials were characterized by scanning electron microscopy (SEM), electron spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (FT-IR) and Raman spectroscopy. When the vacuum heat-treatment temperature is below 80∘C and the atmospheric heat-treatment temperature is below 100∘C, the air purification performance of the film does not change significantly. With the increase in the vacuum heat-treatment temperature, the removal efficiency of PM[Formula: see text] by GO film decreases gradually from 95% to 83%. At different times, the vacuum heat treatment increases with time, and the film removal rate shows a downward trend. As the heat-treatment temperature and time increase, a certain redox reaction occurs in the GO, and the air purification performance decreases. At a temperature of 120∘C and a time of 8[Formula: see text]h, the removal rate drops to 81.68%. The adsorption of PM[Formula: see text] by GO film mainly relies on the action of oxygen-containing functional groups.

New ways of characterizing layered silicates and their intercalates

1984 ◽  
Vol 311 (1517) ◽  
pp. 271-285 ◽  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Resolution Electron Microscopy ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray ◽  
Photoelectron Diffraction ◽  
Organic Species ◽  
New Methods ◽  
Resolution Electron ◽  
Angle Spinning

Four new methods of probing the atomic and microstructural characteristics of the clay minerals are described: solid-state, magic-angle-spinning 27 Al and 29 Si n.m.r. (along with 18 C n.m.r. of mobile, intercalated organic species); X-ray induced photoelectron studies encompassing photoelectron diffraction as a complement to conventional photoelectron spectroscopy; high-resolution electron microscopy either alone or in association with electron-stimulated X-ray emission microanalysis; and neutron scattering techniques. In reviewing the principles, scope and application of these methods specific case histories are selected from representative minerals belonging to the serpentines, kandites, smectites, micas, vermiculites, chloritoids, zeolites and intergrowths of these with one another or with other silicate minerals. Emphasis is placed on problems not readily amenable to solution by traditional, X-ray based procedures.

Sign in / Sign up

Export Citation Format

Share Document