scholarly journals Effect of The Nickel And Temperature Dependent Electrical Properties C-SiO2 -Ni Composites

2021 ◽  
Author(s):  
S. Gouadria ◽  
K. Omri
Keyword(s):  
Small Polaron ◽  
Sol Gel ◽  
Inert Atmosphere ◽  
Metallic Nickel ◽  
Temperature Dependent ◽  
Conduction Model ◽  
Main Band ◽  
Resorcinol Formaldehyde ◽  
Characteristic Lines ◽  
Electrical Characterizations

Abstract The sol-gel method was chosen to synthesize C-SiO2/Ni nanocomposites, silica nanofillers were incorporated into a carbon based on resorcinol-formaldehyde (RF), doped with 5% nickel. During preparation process, they were subjected to a heat treatment of different pyrolysis temperatures and under an inert atmosphere for 2 h. The X- ray diffractogram presented by XRD of the samples treated at low temperatures, indicates the presence of characteristic lines of metallic nickel. FTIR analysis shows the presence of a main band located at about 1050 cm-1, which corresponds to the vibrations of Si-O-Si. From electrical characterizations, the C-SiO2-Ni5%-650 sample has a negative differential resistance‎ behavior (NDR) at low measurement temperatures. According to the I-V characterization, the C-SiO2-Ni5%-625 °C nanocomposite reveals the NDR behavior at room temperature. The conduction mechanism was fitted by two models: the hopping conduction model for the nanocomposite, treated at 650 °C, and the small polaron model for the composite treated at 675 °C.

SYNTHESIS AND CHARACTERIZATION OF PURE AND Zn-DOPED SnO2 NANOPOWDERS

2013 ◽  
Vol 22 ◽  
pp. 452-457 ◽  
Author(s):  
PARUL GUPTA ◽  
RISHI VYAS ◽  
B. L. CHOUDHARY ◽  
K. SACHDEV ◽  
D. S. PATIL ◽  
...  
Keyword(s):  
Gas Sensing ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Sensing Applications ◽  
Zn Addition ◽  
Vis Spectroscopy ◽  
Electrical Characterizations

Pure and 4.5 wt% Zn- doped SnO2 nanopowders were synthesized by sol-gel method. These nanopowders were characterized by X- ray diffraction, Scanning electron microscopy, UV-Vis spectroscopy, I-V measurements and R-T measurements. XRD results confirmed the formation of tetragonal rutile type SnO2 with the average crystallite size of 14 ± 1 nm which decreased to 9 ± 1 nm with 4.5 wt% Zn addition. Increase in band gap is observed from UV-Vis spectroscopy. Electrical characterizations revealed increase in resistivity with Zn addition. Temperature dependent resistance measurement showed that both the pure and the Zn- doped samples are suitable for gas sensing applications. A detailed study of these synthesized nanostructured samples is presented and discussed in the paper.

scholarly journals Selectivity of Tungsten Oxide Synthesized by Sol-Gel Method Towards Some Volatile Organic Compounds and Gaseous Materials in a Broad Range of Temperatures

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 523 ◽  
Author(s):  
Simonas Ramanavičius ◽  
Milda Petrulevičienė ◽  
Jurga Juodkazytė ◽  
Asta Grigucevičienė ◽  
Arūnas Ramanavičius
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Sol Gel ◽  
Temperature Dependent ◽  
Sensing Systems ◽  
Sensing Material ◽  
Operational Temperature ◽  
Volatile Organic ◽  
Different Gases

In this research, the investigation of sensing properties of non-stoichiometric WO3 (WO3−x) film towards some volatile organic compounds (VOC) (namely: Methanol, ethanol, isopropanol, acetone) and ammonia gas are reported. Sensors were tested at several temperatures within the interval ranging from a relatively low temperature of 60 up to 270 °C. Significant variation of selectivity, which depended on the operational temperature of sensor, was observed. Here, the reported WO3/WO3–x-based sensing material opens an avenue for the design of sensors with temperature-dependent sensitivity, which can be applied in the design of new gas- and/or VOC-sensing systems that are dedicated for the determination of particular gas- and/or VOC-based analyte concentration in the mixture of different gases and/or VOCs, using multivariate analysis of variance (MANOVA).

scholarly journals Nonlinear Solution to a Non-Fourier Heat Conduction Problem in a Slab Heated by Laser Source

2016 ◽  
Vol 63 (1) ◽  
pp. 129-144
Author(s):  
Mohammad Javad Noroozi ◽  
Seyfolah Saedodin ◽  
Davood Domiri Ganji
Keyword(s):  
Heat Conduction ◽  
Heat Conduction Problem ◽  
Adomian Decomposition Method ◽  
Laser Source ◽  
Temperature Dependent ◽  
Conduction Model ◽  
Non Linear Equation ◽  
Adomian Decomposition ◽  
Non Linear ◽  
Fourier Heat Conduction

Abstract The effect of laser, as a heat source, on a one-dimensional finite body was studied in this paper. The Cattaneo-Vernotte non-Fourier heat conduction model was used for thermal analysis. The thermal conductivity was assumed temperature-dependent which resulted in a non-linear equation. The obtained equations were solved using the approximate-analytical Adomian Decomposition Method (ADM). It was concluded that the non-linear analysis is important in non-Fourier heat conduction problems. Significant differences were observed between the Fourier and non-Fourier solutions which stresses the importance of non-Fourier solutions in the similar problems.

scholarly journals Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

AIP Advances ◽  
2016 ◽  
Vol 6 (2) ◽  
pp. 025206
Author(s):  
R. Gul ◽  
Y. Cui ◽  
A. E. Bolotnikov ◽  
G. S. Camarda ◽  
S. U. Egarievwe ◽  
...  
Keyword(s):  
Blue Light ◽  
Photocurrent Response ◽  
Temperature Dependent ◽  
Electrical Characterizations

scholarly journals Temperature-dependent structural behaviour of samarium cobalt oxide

2017 ◽  
Vol 32 (S2) ◽  
pp. S38-S42
Author(s):  
Matthew R. Rowles ◽  
Cheng-Cheng Wang ◽  
Kongfa Chen ◽  
Na Li ◽  
Shuai He ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Cobalt Oxide ◽  
Sol Gel ◽  
Linear Thermal Expansion ◽  
Rietveld Analysis ◽  
Structural Behaviour ◽  
Temperature Dependent ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Sol Gel Synthesis

The crystal structure and thermal expansion of the perovskite samarium cobalt oxide (SmCoO3) have been determined over the temperature range 295–1245 K by Rietveld analysis of X-ray powder diffraction data. Polycrystalline samples were prepared by a sol–gel synthesis route followed by high-temperature calcination in air. SmCoO3 is orthorhombic (Pnma) at all temperatures and is isostructural with GdFeO3. The structure was refined as a distortion mode of a parent $ Pm{\bar 3}m $ structure. The thermal expansion was found to be non-linear and anisotropic, with maximum average linear thermal expansion coefficients of 34.0(3) × 10−6, 24.05(17) × 10−6, and 24.10(18) × 10−6 K−1 along the a-, b-, and c-axes, respectively, between 814 and 875 K.

Fabrication of Carbon Aerogels

2006 ◽  
Vol 11-12 ◽  
pp. 19-22 ◽  
Author(s):  
Y.N. Feng ◽  
Lei Miao ◽  
Yong Ge Cao ◽  
T. Nishi ◽  
Sakae Tanemura ◽  
...  
Keyword(s):  
Pore Size ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Limited Range ◽  
Molar Ratio ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Catalyst Content ◽  
Fabrication Parameters ◽  
Pyrolysis Processes

RF (Resorcinol-Formaldehyde) aerogels and carbon aerogels were prepared through the sol-gel method following the routes of polymerization, gelation, supercritical drying and pyrolysis processes. The influence of fabrication parameters on the textural structure of the samples, e.g., specific surface area, pore size, and pore size distribution, etc., were systematically investigated. With a decrease in the R/F molar ratio, or an increase in the catalyst content within a limited range, the porosity of the nanostructure materials increases. The optimal temperature of pyrolysis for RF aerogel was investigated by TGA (Thermogravimetric Analysis).

A facile heating cell forin situtransmittance and fluorescence X-ray absorption spectroscopy investigations

2013 ◽  
Vol 21 (1) ◽  
pp. 165-169 ◽  
Author(s):  
Pengfei An ◽  
Caihao Hong ◽  
Jing Zhang ◽  
Wei Xu ◽  
Tiandou Hu
Keyword(s):  
Absorption Spectroscopy ◽  
Ohmic Heating ◽  
Inert Atmosphere ◽  
Temperature Dependent ◽  
Structural Mechanism ◽  
X Ray ◽  
Novel Approach ◽  
Heat Shielding ◽  
X Ray Absorption

A facile heating cell has been designed forin situtransmittance and fluorescence X-ray absorption spectroscopy (XAS) measurements up to 1273 K under vacuum or an inert atmosphere. These high temperatures are achieved using a tantalum heating element by ohmic heating. Because of the small specific heat capacity, the temperature can be changed in a matter of minutes from room temperature to high temperature. Furthermore, a commercial power controller was adapted to provide stable temperature control. The construction of the heat shielding system provides a novel approach to reducing the beam's path length and the cell's size. The cell is inexpensive and easy to build. Its performance was evaluated byin situXAS measurements of the temperature-dependent structure of ceria nanocrystals. Some preliminary results for the structural mechanism in ceria nanocrystal redox applications are given.

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