scholarly journals Hydrogen Detection with SAW Polymer/Quantum Dots Sensitive Films

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4481 ◽  
Author(s):  
Izabela Constantinoiu ◽  
Cristian Viespe
Keyword(s):  
Heat Treatment ◽  
Quantum Dots ◽  
Room Temperature ◽  
Limit Of Detection ◽  
Composite Films ◽  
High Specific Surface Area ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Heat Treated ◽  
Gas Molecules

Regarding the use of hydrogen as a fuel, it is necessary to measure its concentration in air at room temperature. In this paper, sensitive composite films have been developed for surface acoustic wave (SAW) sensors, using quantum dots (QDs) and polymers. Si/SiO2 QDs were used due to having a high specific surface area, which considerably improves the sensitivity of the sensors compared to those that only have a polymer. Si/SiO2 QDs were obtained by laser ablation and analyzed by X-ray diffraction and transmission electron microscopy (TEM). Two types of polymers were used: polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA). Polymer and polymer with QDs compositions were deposited on the sensor substrate by drop casting. A heat treatment was performed on the films at 80 °C with a thermal dwell of two hours. The sensors obtained were tested at different hydrogen concentrations at room temperature. A limit of detection (LOD) of 452 ppm was obtained by the sensor with PDMS and Si/SiO2 QDs, which was heat treated. The results demonstrated the potential of using QDs to improve the sensitivity of the SAW sensors and to achieve a heat treatment that increases its adsorption capacity of the gas molecules.

scholarly journals Preparation and Assessment of Heat-Treated α-Chitin Nanowhiskers Reinforced Poly(viny alcohol) Film for Packaging Application

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1883 ◽  
Author(s):  
Chao Peng ◽  
Guangxue Chen
Keyword(s):  
Heat Treatment ◽  
Composite Films ◽  
Barrier Properties ◽  
Mechanical Tests ◽  
Light Transmittance ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Chitin Nanowhiskers

In this study, poly(vinyl alcohol) (PVA) composite films enhanced by α-chitin nanowhiskers (ChWs) were prepared through heat treatment. The obtained membranes were assessed by means of FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis, regular light transmittance, mechanical tests, permeability and water absorption. The influence of the nano-component and heat treatment on the mechanical, thermal and water-resistant properties of the composite membrane were analyzed. From the results of the work, the produced films with excellent barrier properties and inexpensive raw processed materials have great prospects in packaging applications.

Copper(I) Halide Nanoparticle-dispersed Glasses Prepared by Copper Staining

2005 ◽  
Vol 20 (9) ◽  
pp. 2480-2485 ◽  
Author(s):  
Kohei Kadono ◽  
Tatsuya Suetsugu ◽  
Takeshi Ohtani ◽  
Toshihiko Einishi ◽  
Takashi Tarumi ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Surface Region ◽  
Borosilicate Glasses ◽  
X Ray Diffraction ◽  
X Ray ◽  
Depth Profiles ◽  
Transmission Electron ◽  
Heat Treated ◽  
Glass Heat

Copper(I) chloride and bromide nanoparticle-dispersed glasses were prepared by means of a conventional copper staining. The staining was performed by the following process: copper stain was applied on the surfaces of Cl−- or Br−-ion-containing borosilicate glasses, and the glasses were heat-treated at 510 °C for various times. Typical exciton bands observed in the absorption spectra of the glasses after the heat treatment indicated that CuCl and CuBr particles were formed in the surface region of the glasses. The average sizes of the CuCl and CuBr particles in the glasses heat-treated for 48 h were estimated at 4.8 and 2.7 nm, respectively. The nanoparticles were also characterized by x-ray diffraction and transmission electron microscopy. Depth profiles of Cu and CuBr concentration in the glass heat-treated for 48 h were measured. Copper decreased in concentration monotonously with depth, reaching up to 60 μm, while the CuBr concentration had a maximum at about 25 μm in depth.

scholarly journals Room Temperature Detection of Acetone by a PANI/Cellulose/WO3Electrochemical Sensor

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Eider Aparicio-Martínez ◽  
Velia Osuna ◽  
Rocio B. Dominguez ◽  
Alfredo Márquez-Lucero ◽  
E. Armando Zaragoza-Contreras ◽  
...  
Keyword(s):  
Room Temperature ◽  
Electrochemical Impedance ◽  
Limit Of Detection ◽  
X Ray Diffraction ◽  
Acetone Concentration ◽  
Temperature Detection ◽  
Transmission Electron ◽  
Semiconducting Metal Oxides ◽  
Acetone Detection ◽  
Synthesized Materials

Chemical sensing based on semiconducting metal oxides has been largely proposed for acetone sensing, although some major technical challenges such as high operating temperature still remain unsolved. This work presents the development of an electrochemical sensor based on nanostructured PANI/cellulose/WO3composite for acetone detection at room temperature. The synthesized materials for sensor preparation were polyaniline (PANI) with a conductivity of 13.9 S/cm and tungsten trioxide (WO3) in monoclinic phase doped with cellulose as carbon source. The synthesized materials were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), cyclic voltammetry (CV), and Raman spectroscopy. The composite was applied for acetone detection in the range of 0 to 100 ppmv at room temperature with electrochemical impedance spectroscopy (EIS) for monitoring resistance changes proportional to acetone concentration. The developed sensor achieved a calculated limit of detection of 10 ppm andR2of 0.99415 with a RSD of 5% (n=3) at room temperature. According to these results, the developed sensor is suitable for acetone sensing at room temperatures without the major shortcomings of larger systems required by high operating temperatures.

Heat Treatment of Nanocrystalline Al2O3-Zr02

1996 ◽  
Vol 457 ◽  
Author(s):  
Bridget M. Smyser ◽  
Jane F. Connelly ◽  
Richard D. Sisson ◽  
Virgil Provenzano
Keyword(s):  
Electron Microscopy ◽  
Heat Treatment ◽  
Grain Size ◽  
Monoclinic Phase ◽  
Phase Distribution ◽  
Critical Size ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated

ABSTRACTThe effects of grain size on the phase transformations in nanocrystalline ZrO2-Al2O3 have been experimentally investigated. Compositions from 10 to 50 vol% Al2O3 in ZrO2 were obtained as a hydroxide gel. The powders were then calcined at 600 °C for 17 hours and heat treated at 1100 °C for 24 and 120 hours and at 1200 °C for 2 hours. The phase distribution and grain size were determined using x-ray diffraction and transmission electron microscopy. The initial grain size after calcining was 8–17 nm. It was determined that the critical ZrO2 grain size to avoid the tetragonal to monoclinic phase transformation on cooling from 1100 °C was between 17 and 25 nm. Samples containing 50% Al2O3 maintained a grain size below the critical size for all times and temperatures. The 30% Al2O3 samples showed the same behavior in all but one heat treatment. The remainder of the samples showed significant grain growth and at least partial transformation to the monoclinic phase.

The Effect of Heat Treatment on the Corrosion Behavior of Amorphous Mg–Ni–Nd Alloys

1999 ◽  
Vol 14 (4) ◽  
pp. 1638-1644 ◽  
Author(s):  
C. H. Kam ◽  
Y. Li ◽  
S. C. Ng ◽  
A. Wee ◽  
J. S. Pan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Corrosion Behavior ◽  
Amorphous Matrix ◽  
Nacl Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Heat Treated ◽  
Uniform Dispersion ◽  
Melt Spun

The effect of heat treatment on the corrosion behavior of seven amorphous melt-spun Mg–Ni–Nd alloys containing 10–20 at.% Ni and 5–15 at.% Nd has been studied. Hydrogen evolution testing was used to determine the dissolution rate of the heat-treated specimens immersed in a 3% NaCl solution saturated with Mg(OH)2. The dissolution rates of the partially crystallized specimens were found to be lower than those of the untreated specimens, while the fully crystallized specimens exhibited marked deterioration of corrosion resistance. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies on the heat-treated specimens revealed precipitation of Mg3Nd, Mg12Nd, and Mg2Ni phases during the crystallization. TEM results show that the partially crystallized structure consists of uniform dispersion of either Mg3Nd or Mg2Ni in the amorphous matrix. In contrast, multiple phases precipitate in the fully crystallized specimen.

X-Ray Stress Studies of Passivated and Unpassivated Narrow Aluminum Metallizations

1990 ◽  
Vol 188 ◽  
Author(s):  
C. A. Paszkiet ◽  
M. A. Korhonen ◽  
Che-Yu Li
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Nitrogen Atmosphere ◽  
Passivation Layer ◽  
Apparent Stress ◽  
X Ray Diffraction ◽  
X Ray ◽  
Stress Studies ◽  
Heat Treated ◽  
Measurement Period

ABSTRACTStresses in thin narrow textured metal lines were measured using x-ray diffraction techniques. Arrays of 1.5μm wide, 0.32μm thick aluminum lines, both with and without a 0.32μm thick SiNx passivation layer, were heat-treated at 400°C in a hydrogen/nitrogen atmosphere. After heat treatment the lines were examined periodically using chromium radiation to monitor the relaxation of the stress developed during heat treatment. The apparent stress in both the passivated and unpassivated lines relaxed significantly over the measurement period of three days. The higher stresses present in the passivated lines may be partially responsible for the voids which were found after aging at room temperature.

EFFECT OF HEAT TREATMENT ON THE STRUCTURE OF SiC−Si3N4 COMPOSITE ULTRAFINE POWDER

1996 ◽  
Vol 03 (01) ◽  
pp. 79-83 ◽  
Author(s):  
X. LI ◽  
Y. NAKATA ◽  
H. NAGAI ◽  
T. OKUTANI ◽  
M. SUZUKI
Keyword(s):  
Heat Treatment ◽  
Particle Size ◽  
Lattice Parameter ◽  
Ultrafine Powder ◽  
Phase Reaction ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
Transmission Electron ◽  
Heat Treated ◽  
Original Powder

Effect of heat treatment on the structure of SiC−Si3N4 composite ultrafine powder was studied. SiC-Si3N4 composite ultrafine powder synthesized by laser-induced gas-phase reaction was heat-treated at various temperatures below 1773 K in 99% Ar +1% H2 gas mixture. The change of the structure was studied by chemical analysis, x-ray diffraction (XRD), and transmission electron microscope (TEM). The structure of the powder did not change significantly in lattice constant, particle size, and composition by the treatment up to 1573 K . The structure of the powder changed drastically by the treatment above 1673 K . The broad XRD pattern due to β- Si for the original powder changed to the four phases of β- SiC , Si and α, β- Si 3N4 by the treatment at 1773 K , accompanied by large increases in particle size and lattice parameter, and decreases in nitrogen content and specific surface area.

The Effect of Hot Rolling on Room Temperature Ductility of a NiAl Intermetallic Compound

2006 ◽  
Vol 509 ◽  
pp. 69-74 ◽  
Author(s):  
Sergio Garcia-Galan ◽  
Gerardo Aramburo-Perez ◽  
Carlos González-Rivera ◽  
R. Herrera ◽  
J.A. Juárez-Islas
Keyword(s):  
Grain Boundaries ◽  
Room Temperature ◽  
Vacuum Induction Melting ◽  
Induction Melting ◽  
X Ray Diffraction ◽  
Room Temperature Ductility ◽  
Transmission Electron ◽  
Heat Treated ◽  
Effect Of Hot Rolling ◽  
Hot Rolled

A Ni57Fe18Al25 alloy is produced by vacuum induction melting under an argon atmosphere and gravity cast into a copper chill mould. Ingots of 2 x 10 x 50 mm are re-heated at 1100 °C for 24 hours and hot rolled until a 25 % reduction is reached. Immediately, hot rolled plates are heat treated at 1100 °C for 1 hour and water cooled to room temperature. Microstructures of as cast, hot rolled and hot rolled plus heat treated specimens are characterized using scanning and transmission electron microscopy and x-ray diffraction. Specimens in the as-cast and hot rolled conditions show the presence of equiaxial and partially elongated β-grains, respectively, with the presence of a thin γ-phase decorating the grain boundaries. Hot rolled plus heat treated specimens have partially recrystallized β-grains with γ-phase and (Ni,Fe)3Al at the grain boundaries. The hot rolled specimens have a room temperature ductility of approximately 5 % in tensile testing. This enhancement in ductility is attributed to the modification of the β-grains by coexistence with a γ- phase along the grain boundaries.

Preparation of Ta-12.5Si-25B Powders by Mechanical Alloying

2006 ◽  
Vol 530-531 ◽  
pp. 197-202 ◽  
Author(s):  
Alfeu Saraiva Ramos ◽  
Erika Coaglia Trindade Ramos ◽  
Carlos de Moura Neto
Keyword(s):  
Heat Treatment ◽  
Ball Milling ◽  
Room Temperature ◽  
Intermetallic Phase ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Unknown Phase ◽  
Heat Treated ◽  
Equilibrium Microstructure

The present work reports on the preparation of the Ta5SiB2 compound by highenergy ball milling and subsequent heat treatment from elemental Ta-12.5at%Si-25at%B powder mixture. The milling process was carried out at room temperature in a planetary ball mill under argon atmosphere. Following the milling process, the powders were heat-treated at 1200oC for 4h under Ar atmosphere in order to obtain the equilibrium microstructure. The milled and heat-treated powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated that the Si peaks disappeared after milling for 1h. It was noted that the broadening and the reduced intensity of Ta peaks occurred continuously up to milling for 10h, suggesting that the Si and B atoms were preferentially dissolved into the Ta lattice during ball milling to form a supersaturated solid solution. A halo was formed in Ta-12.5at%Si-25at%B powders milled for 100h, suggesting that an amorphous phase was achieved. No intermetallic phase was formed in powders milled for 200h. A large amount of Ta5SiB2 was formed after heat treatment at 1200oC for 4h. In addition, peaks of TaB and another unknown phase were also identified.

scholarly journals Dual Electrochemical Treatments to Improve Properties of Ti6Al4V Alloy

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2479
Author(s):  
Stefano Rossi ◽  
Luciana Volgare ◽  
Carine Perrin-Pellegrino ◽  
Carine Chassigneux ◽  
Erick Dousset ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Combined Treatment ◽  
Amorphous Film ◽  
Amorphous Layer ◽  
Good Alternative ◽  
Surface Treatments ◽  
Ex Situ ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Fluid Environment

Surface treatments are considered as a good alternative to increase biocompatibility and the lifetime of Ti-based alloys used for implants in the human body. The present research reports the comparison of bare and modified Ti6Al4V substrates on hydrophilicity and corrosion resistance properties in body fluid environment at 37 °C. Several surface treatments were conducted separately to obtain either a porous oxide layer using nanostructuration (N) in ethylene glycol containing fluoride solution, or bulk oxide thin films through heat treatment at 450 °C for 3 h (HT), or electrochemical oxidation at 1 V for 3 h (EO), as well as combined treatments (N-HT and N-EO). In-situ X-ray diffraction and ex-situ transmission electron microscopy have shown that heat treatment gave first rise to the formation of a 30 nm thick amorphous layer which crystallized in rutile around 620 °C. Electrochemical oxidations gave rise to a 10 nm thick amorphous film on the top of the surface (EO) or below the amorphous nanotube layer (N-EO). Dual treated samples presented similar results with a more stable behavior for N-EO. Finally, for both corrosion and hydrophilicity points of view, the new combined treatment to get a total amorphous N-EO sample seems to be the best and even better than the partially crystallized N-HT sample.

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