Influence of pH on particle size, band-gap and activation energy of CdS nanoparticles synthesized at constant frequency ultrasonic wave irradiation

2017 ◽  
Vol 66 ◽  
pp. 131-139 ◽  
Author(s):  
V. Mohanraj ◽  
R. Jayaprakash ◽  
J. Chandrasekaran ◽  
R. Robert ◽  
P. Sangaiya
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Band Gap ◽  
Ultrasonic Wave ◽  
Cds Nanoparticles ◽  
Constant Frequency ◽  
Influence Of Ph

Growth of nanocrystalline PbS within a glass

1997 ◽  
Vol 12 (10) ◽  
pp. 2507-2510 ◽  
Author(s):  
M. Mukherjee ◽  
A. Datta ◽  
D. Chakravorty
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Band Gap ◽  
Sodium Ion ◽  
Oxide Glass ◽  
Dc Resistivity ◽  
Ion Migration ◽  
Temperature Range ◽  
Resistivity Variation ◽  
O 15

Nanocrystalline PbS has been grown within a phase-separated oxide glass of composition 10 Na2O, 15 PbO, 17 CaO, 3 Bi2O3, and 55 SiO2 (in mole %) by passing H2S gas over it at temperatures varying from 773 to 943 K. The particle size ranged from 2.5 to 12.9 nm. The dc resistivity of composites of nanocrystalline PbS and the phase separated glass has been measured over the temperature range 300 to 670 K. The resistivity variation in the temperature range 550 to 670 K is characterized by the sodium ion migration in the glass with an activation energy, ∼1.2 eV. The resistivity in the range 300 to 500 K was controlled by conduction in PbS particles with the estimated band gap showing an increase with a decrease in the particle size.

OPTICAL PROPERTIES OF CHEMICALLY PREPARED CdS QUANTUM DOTS IN POLYVINYL ALCOHOL

2009 ◽  
Vol 23 (04) ◽  
pp. 545-555 ◽  
Author(s):  
J. BARMAN ◽  
J. P. BORAH ◽  
K. C. SARMA
Keyword(s):  
Quantum Dots ◽  
Particle Size ◽  
Band Gap ◽  
Blue Shift ◽  
Cds Nanoparticles ◽  
Cds Quantum Dots ◽  
Chemical Route ◽  
Visible Absorption ◽  
Weak Band ◽  
Composite Band

Excitonic effects are observed in the optical absorption and photoluminescence of strongly confined CdS quantum dots embedded in the polymer matrix. CdS nanoparticles of different crystallite sizes have been prepared by chemical route with polymer as a host material. The CdS nanocomposite film was made up of particle smaller than 5 nm and shows a composite band gap up to 3.2 eV, whereas the band gap for bulk hexagonal CdS is about 2.42 eV. Photoluminescence spectra show a strong emission band corresponding to electron–hole recombination and a weak band due to defect emission. The decrease of particle size was monitored from the U-V visible absorption measurement as well as photoluminescence, which suffered blue shift with decrease in particle size. The particle size and surface morphology were also analyzed by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM).

Energy Band Gap Studies of CdS Nanomaterials

2008 ◽  
Vol 3 ◽  
pp. 97-102 ◽  
Author(s):  
Dinu Patidar ◽  
K.S. Rathore ◽  
N.S. Saxena ◽  
Kananbala Sharma ◽  
T.P. Sharma
Keyword(s):  
Optical Absorption ◽  
Band Gap ◽  
Energy Band ◽  
Chemical Method ◽  
Optical Absorption Spectroscopy ◽  
Cds Nanoparticles ◽  
X Ray Diffraction ◽  
Energy Band Gap ◽  
X Ray ◽  
Simple Chemical

The CdS nanoparticles of different sizes are synthesized by a simple chemical method. Here, CdS nanoparticles are grown through the reaction of solution of different concentration of CdCl2 with H2S. X-ray diffraction pattern confirms nano nature of CdS and has been used to determine the size of particle. Optical absorption spectroscopy is used to measure the energy band gap of these nanomaterials by using Tauc relation. Energy band gap ranging between 3.12 eV to 2.47 eV have been obtained for the samples containing the nanoparticles in the range of 2.3 to 6.0 nm size. A correlation between the band gap and size of the nanoparticles is also established.

Nitrocellulose Catalyzed With Manganese Oxide Nanoparticles: Advanced Energetic Nanocomposite With Superior Decomposition Kinetics

2021 ◽  
Author(s):  
Sherif Elbasuney ◽  
M. Yehia ◽  
Shukri Ismael ◽  
Yasser El-Shaer ◽  
Ahmed Saleh
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Manganese Oxide ◽  
Energetic Materials ◽  
Average Particle Size ◽  
Active Surface ◽  
Propagation Rate ◽  
Hydroxyl Groups ◽  
Average Particle ◽  
Decomposition Enthalpy

Abstract Nanostructured energetic materials can fit with advanced energetic first-fire, and electric bridges (microchips). Manganese oxide, with active surface sites (negatively charged surface oxygen, and hydroxyl groups) can experience superior catalytic activity. Manganese oxide could boost decomposition enthalpy, ignitability, and propagation rate. Furthermore manganese oxide could induce vigorous thermite reaction with aluminium particles. Hot solid or liquid particles are desirable for first-fire compositions. This study reports on the facile fabrication of MnO2 nanoparticles of 10 nm average particle size; aluminium nanoplates of 100 nm average particle size were employed. Nitrocellulose (NC) was adopted as energetic polymeric binder. MnO2/Al particles were integrated into NC matrix via co-precipitation technique. Nanothermite particles offered an increase in NC decomposition enthalpy by 150 % using DSC; ignition temperature was decreased by 8 0C. Nanothemrite particles offered enhanced propagation index by 261 %. Kinetic study demonstrated that nanothermite particles experienced drastic decrease in NC activation energy by - 42, and - 40 KJ mol-1 using Kissinger and KAS models respectively. This study shaded the light on novel nanostructured energetic composition, with superior combustion enthalpy, propagation rate, and activation energy.

scholarly journals Green Preparation, Spheroidal, and Superior Property of Nano-1,3,5,7-Tetranittro-1,3,5,7-Tetrazocane

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xinlei Jia ◽  
Jingyu Wang ◽  
Conghua Hou ◽  
Yingxin Tan
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fractal Theory ◽  
Crystal Form ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
The Impact

Herein, a green process for preparing nano-HMX, mechanical demulsification shearing (MDS) technology, was developed. Nano-HMX was successfully fabricated via MDS technology without using any chemical reagents, and the fabrication mechanism was proposed. Based on the “fractal theory,” the optimal shearing time for mechanical emulsification was deduced by calculating the fractal dimension of the particle size distribution. The as-prepared nano-HMX was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). And the impact sensitivities of HMX particles were contrastively investigated. The raw HMX had a lower fractal dimension of 1.9273. The ideal shearing time was 7 h. The resultant nano-HMX possessed a particle size distribution ranging from 203.3 nm to 509.1 nm as compared to raw HMX. Nano-HMX particles were dense spherical, maintaining β-HMX crystal form. In addition, they had much lower impact sensitivity. However, the apparent activation energy as well as thermal decomposition temperature of nano-HMX particles was decreased, attributing to the reduced probability for hotspot generation. Especially when the shearing time was 7 h, the activation energy was markedly decreased.

High Tc Oxide Solid State Reaction Kinetics Via Complex Impedance Spectroscopy

1989 ◽  
Vol 169 ◽  
Author(s):  
E. A. Cooper ◽  
T. O. Mason ◽  
U. Balachandran ◽  
M. L. Kullberg
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Solid State ◽  
Solid State Reaction ◽  
Complex Impedance ◽  
Particle Size Effect ◽  
Large Temperature ◽  
Impedance Spectra ◽  
High Tc ◽  
Solid State Reaction Kinetics

AbstractImpedance spectra (5Hz ‐ 13MHz) were collected during the solid state reaction of Yba2Cu2O6+y from large monosized CuO particles imbedded in a finely divided Y2 O3 /BaCO3 matrix. No particle size effect was observed, but a large temperature effect was observed corresponding to an activation energy of approximately 1.8eV (175kJ/mol) over the range 700‐900°C.

scholarly journals Preparation of Apatite-Wollastonite-Phlogopite glass-ceramic composites by powder sintering method

2013 ◽  
Vol 45 (3) ◽  
pp. 331-339
Author(s):  
A. Faeghi-Nia
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Glass Ceramic ◽  
Ceramic Composite ◽  
Ceramic Composites ◽  
Powder Sintering ◽  
Powdered Glass ◽  
Activation Energy Of Sintering ◽  
Sintering Method ◽  
Glass Ceramic Composite

An Apatite-Wollastonite-Phlogopite glass-ceramic composite, was developed by sintering and crystallization of the powdered glass. The non-isothermal and isothermal sintering kinetics were studied for this glass-ceramic. Hot-stage microscopy (HSM) measurements demonstrated that it is possible to sinter and crystallize this glass-ceramic with 80% relative density. The activation energy of sintering was analyzed using previously reported model of sintering and it was obtained Q=193.83 KjmolK-1. Also it was shown that the microstructure of sample is a function of particle size distribution.

Sign in / Sign up

Export Citation Format

Share Document