scholarly journals Carrier recombination in sonochemically synthesized ZnO powders

2017 ◽  
Vol 35 (1) ◽  
pp. 211-216 ◽  
Author(s):  
M.I. Zakirov ◽  
O.A. Korotchenkov
Keyword(s):  
Surface Defects ◽  
Sonochemical Method ◽  
Photoluminescence Spectra ◽  
Carrier Recombination ◽  
Convenient Means ◽  
Recombination Processes ◽  
Stirring Time ◽  
Zno Powders ◽  
Ft Ir ◽  
Volume Defect

AbstractZnO powders with particle size in the nm to μm range have been fabricated by sonochemical method, utilizing zinc acetate and sodium hydroxide as starting materials. Carrier recombination processes in the powders have been investigated using the photoluminescence, FT-IR and surface photovoltage techniques. It has been shown that the photoluminescence spectra exhibit a number of defect-related emission bands which are typically observed in ZnO lattice and which depend on the sonication time. It has been found that the increase of the stirring time results in a faster decay of the photovoltage transients for times shorter than approximately 5 ms. From the obtained data it has been concluded that the sonication modifies the complicated trapping dynamics from volume to surface defects, whereas the fabrication method itself offers a remarkably convenient means of modifying the relative content of the surface-to-volume defect ratio in powder grains and altering the dynamics of photoexcited carriers.

Luminescent Properties of Zn2SiO4:Eu3+,Dy3+ Phosphors via Sol-Gel Process

2012 ◽  
Vol 217-219 ◽  
pp. 733-736
Author(s):  
Xiu Mei Han ◽  
Shu Ai Hao ◽  
Ying Ling Wang ◽  
Gui Fang Sun ◽  
Xi Wei Qi
Keyword(s):  
Thermal Analysis ◽  
Ir Spectra ◽  
Sol Gel ◽  
Luminescent Properties ◽  
Photoluminescence Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sol Gel Process ◽  
Ft Ir

Zn2SiO4:Eu3+, Dy3+ phosphors have been prepared through the sol-gel process. X-ray diffraction (XRD), thermogravimetric and ddifferential thermal analysis (TG-DTA), FT-IR spectra and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1000oC. In Zn2SiO4:Eu3+,Dy3+ phosphors, the Eu3+ and Dy3+ show their characteristic red(613nm, 5D0-7F2), blue (481nm, 4F9/2–6H15/2) and yellow (577nm, 4F9/2–6H13/2) emissions.

scholarly journals Numerical study on the optical and carrier recombination processes in GeSn alloy for E-SWIR and MWIR optoelectronic applications

2016 ◽  
Vol 24 (23) ◽  
pp. 26363 ◽  
Author(s):  
Stefano Dominici ◽  
Hanqing Wen ◽  
Francesco Bertazzi ◽  
Michele Goano ◽  
Enrico Bellotti
Keyword(s):  
Numerical Study ◽  
Carrier Recombination ◽  
Recombination Processes ◽  
Optoelectronic Applications ◽  
Gesn Alloy

scholarly journals Synthesis of Cinnamic Acid Based on Perkin Reaction Using Sonochemical Method and Its Potential as Photoprotective Agent

2020 ◽  
Vol 5 (1) ◽  
pp. 54
Author(s):  
Erwin Indriyanti ◽  
Masitoh Suryaning Prahasiwi
Keyword(s):  
Antioxidant Activity ◽  
Melting Point ◽  
Cinnamic Acid ◽  
Wave Number ◽  
Sonochemical Method ◽  
H Nmr ◽  
Ft Ir ◽  
Perkin Reaction ◽  
Pharmaceutical Industries ◽  
C Nmr

<p>Cinnamic acid plays a vital role in the synthesis of other important compounds and as a precursor for the synthesis of commercial cinnamon esters used in perfumery, cosmetics, and pharmaceutical industries. The aim of this research is to synthesize cinnamic acid using sonochemical methods. Cinnamic acid was synthesized using Perkin reaction by reacting 0.05 mole of benzaldehyde with 0.073 mole of acetic acid anhydride and 0.03 mole of sodium acetate as a catalyst in the Erlenmeyer flask and then the mixture was put in a sonicator for 60 minutes at 70 <sup>o</sup>C. The synthesized compound was tested organoleptic properties, and the melting point was measured. The chemical structure was elucidated using FT-IR, H-NMR, and <sup>13</sup>C-NMR. The photoprotective activity was examined from its antioxidant and SPF values. The synthesized compound was found in the form of a shiny white fine crystal which had distinctive odor with a yield of 4.98% and the melting point was found at 133<sup> o</sup>C. In the structure elucidation using FT-IR (the aromatic ring absorption at the wave number 1580 cm<sup>-1</sup> -1600 cm<sup>-1</sup>. The wave number 1625 cm<sup>-1</sup>is an aromatic conjugated alkene group, while wave  number 1689.4 cm<sup>-1 </sup>is a carbonyl group. The wave number 2500 cm<sup>-1 </sup>– 3250 cm<sup>-1 </sup>is an OH carboxylic acid group) , H-NMR (7.410 (<em>m</em>, 5H, Ar-H); 7.425(<em>t</em>, 1H); 7.572 (<em>d</em>, 1H); 8.057 (d, 1H,C=CH) and <sup>13</sup>C-NMR (129.309 ppm; 130.998 ppm; 134.58 ppm; 170.017 ppm) showed that when compared with the standard compound as the reference, the synthesized compound was confirmed to be cinnamic acid. The antioxidant activity test showed that at the concentration of 20 ppm the synthesized compound was able to reduce free radicals by 46.69%. This finding showed that  the synthesized compound had antioxidant activity.</p>

Carrier recombination processes in 1.3 μm and 1.5 μm InGaAs(P)-based lasers at cryogenic temperatures and high pressures

2004 ◽  
Vol 241 (14) ◽  
pp. 3399-3404 ◽  
Author(s):  
S. J. Sweeney ◽  
S. R. Jin ◽  
C. N. Ahmad ◽  
A. R. Adams ◽  
B. N. Murdin
Keyword(s):  
High Pressures ◽  
Cryogenic Temperatures ◽  
Carrier Recombination ◽  
Recombination Processes

Ultraslow carrier recombination processes close to Dirac point in graphene/hBN heterostructures (Conference Presentation)

2020 ◽  
Author(s):  
Juliette Mangeney ◽  
Panhui Huang ◽  
Simon Messelot ◽  
Holger Graef ◽  
Jerome Tignon ◽  
...  
Keyword(s):  
Dirac Point ◽  
Carrier Recombination ◽  
Recombination Processes

Roles of carbon impurities and intrinsic nonradiative recombination centers on the carrier recombination processes of GaN crystals

2019 ◽  
Vol 13 (1) ◽  
pp. 012004 ◽  
Author(s):  
Kazunobu Kojima ◽  
Fumimasa Horikiri ◽  
Yoshinobu Narita ◽  
Takehiro Yoshida ◽  
Hajime Fujikura ◽  
...  
Keyword(s):  
Nonradiative Recombination ◽  
Carrier Recombination ◽  
Carbon Impurities ◽  
Recombination Processes ◽  
Recombination Centers

Exciton and Defect Photoluminescence Signatures in Single Crystal Rubrene

2006 ◽  
Vol 965 ◽  
Author(s):  
Oleg Mitrofanov ◽  
David V Lang ◽  
Christian Kloc ◽  
Theo Siegrist ◽  
Woo-Young So ◽  
...  
Keyword(s):  
Radiative Recombination ◽  
Photoluminescence Spectra ◽  
Photoluminescence Band ◽  
Exciton Dissociation ◽  
Acceptor Center ◽  
Oxygen Related Defect ◽  
Recombination Processes ◽  
Photo Conductivity ◽  
Exciton Recombination ◽  
Related Defect

ABSTRACTRadiative recombination processes provide valuable information about exciton dynamics and allow detection of defects in rubrene crystals. We demonstrate that the photoluminescence spectra of crystalline rubrene reflect exciton dissociation through oxygen-related defects in addition to the direct exciton recombination. The defect-assisted exciton dissociation results in a well-defined photoluminescence band. These defects play an important role in charge transport. Dark- and photo-conductivity is higher in rubrene crystals with a large density of the defects. The observations strongly suggest that the oxygen-related defect forms a bandgap state and acts as an acceptor center in crystalline rubrene.

Structural and Magnetic Properties of Cobalt and Aluminum Co-Doped ZnO Powders

2008 ◽  
Vol 47-50 ◽  
pp. 600-603
Author(s):  
Yan Yan Wei ◽  
Deng Lu Hou ◽  
Rui Bin Zhao ◽  
Zhen Zhen Zhou ◽  
Cong Mian Zhen ◽  
...  
Keyword(s):  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Sol Gel ◽  
Ferromagnetic Behavior ◽  
Infrared Transmission ◽  
X Ray Diffraction ◽  
Al Content ◽  
Infrared Reflection ◽  
Zno Powders ◽  
Ft Ir

A series of Zn0.95-xCo0.05AlxO (x=0, 0.01, 0.02, 0.05, 0.08, 0.10) powders with different percentages of aluminum was fabricated using the sol-gel method. X-ray diffraction (XRD) revealed that the Co ions and Al ions substitute for Zn2+ ions without changing the wurtzite structure. No impurity phases were found. No clusters or precipitates of cobalt or aluminum were found using scanning electron microscope analysis. Fourier transform-infrared reflection (FT-IR) spectrometry was used to examine the infrared transmission properties and revealed that Co ions were incorporated into the lattice as Co2+ substituting for Zn2+. Ferromagnetic behavior in the samples was obtained at room temperature. As the Al content x increased, the room temperature ferromagnetism of the samples was reduced, and when x increased to 0.08, the room temperature ferromagnetism disappeared.

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