Photoluminescence of Laser-Synthesized Anatase Titanium Dioxide Nanopowders

2005 ◽  
Vol 494 ◽  
pp. 265-270 ◽  
Author(s):  
M. Šćepanović ◽  
Z. Dohčević-Mitrović ◽  
I. Hinić ◽  
M. Grujić-Brojčin ◽  
G. Stanišić ◽  
...  
Keyword(s):  
Grain Size ◽  
Titanium Dioxide ◽  
Light Emission ◽  
Surface States ◽  
Excitation Power ◽  
Anatase Tio2 ◽  
Tio2 Nanocrystals ◽  
Pl Spectra ◽  
Preparation Conditions ◽  
Tio2 Nanopowders

Titanium dioxide (TiO2) nanopowders were prepared by laser-induced pyrolysis. Raman scattering showed that prepared TiO2 nanocrystals have anatase TiO2 structure. Specific surface area of the powders varies from 84 to 110 m2/g, while the grain size of nanoparticles is between 30 and 70 nm, depending on preparation conditions. We measured photoluminescence (PL) spectra of TiO2 nanocrystals. Under laser irradiation with photon energy between 2.41 and 2.71 eV the TiO2 nanocrystals displayed strong visible light emission, even at excitation power as low as 0.05 W/cm2. The line shape and position of this broad luminescence band vary with excitation energy. As PL spectra of anatase TiO2 can be attributed to three kinds of physical origins (self-trapped excitons, surface states and oxygen vacancies) in this paper we try to resolve which of them are dominant for different TiO2 nanopowders of different grain size.

Size-Dependence of Photoluminescence Property of ZnO Nanoparticles

2014 ◽  
Vol 887-888 ◽  
pp. 143-146 ◽  
Author(s):  
Xiao Fang Wang ◽  
Yun Liang Fang ◽  
Tian Le Li ◽  
Fu Juan Wang
Keyword(s):  
Grain Size ◽  
Lower Energy ◽  
Size Dependence ◽  
Surface States ◽  
Photoluminescence Property ◽  
Precipitation Method ◽  
Pl Spectra ◽  
Broadband Emission ◽  
Band Emission ◽  
20 Nm

Nanometer-sized ZnO crystals with the diameter from 20 nm to 110 nm were prepared by homogenous precipitation method (HPM). The photoluminescence (PL) spectra of as-prepared nanoparticles under excitation at the wavelength of 320 nm were detected. The PL spectra were fitted with Gaussian curves, in which a good fitting consisting of six Gaussian peaks was obtained. We observed that the multi-peak centers do not change much, while the relative amplitude of Gaussian combination to the band-to-band emission decreases rapidly with the increased grain size. It shows that the broadband emission at the lower energy is associated with the surface states.

Photo-and Electro-Luminescence in Copper Doped Zinc Sulphide Nanoparticles and Nanocomposites

2013 ◽  
Vol 201 ◽  
pp. 181-196 ◽  
Author(s):  
Meera Ramrakhiani ◽  
Sakshi Sahare
Keyword(s):  
High Efficiency ◽  
Light Emission ◽  
Green Light ◽  
Surface States ◽  
Blue Shift ◽  
Zinc Sulphide ◽  
Nanocomposite Films ◽  
Chemical Route ◽  
Violet Emission ◽  
Pl Spectra

Copper doped Zinc Sulfide (ZnS:Cu)) is a known green light emitter. Present paper reports luminescence of ZnS:Cu nanoparticles and nanocomposites. Three different nanostructures: mercaptoethanol capped ZnS:Cu nanoparticles, polyvinyl alcohol (PVA) capped ZnS:Cu nanoparticles and ZnS:Cu/PVA nanocomposites have been prepared by chemical route. X-ray diffraction (XRD) revealed cubic zinc blende structure of ZnS:Cu nanocrystals of size below 20 nm. The particle size is found to decrease with increasing capping agent concentration or ZnS loading in PVA matrix. Optical absorption spectra show blue shift in the absorption edge indicating quantum size effect. Photoluminescence (PL) of all the samples was studied by exciting with 212 nm light. The PL spectra of ZnS:Cu/ PVA nanocomposite films show quite broad emission peak at 415 nm where as the PL spectra of mercaptoethanol capped and PVA capped nanoparticles show a very narrow peak at 426 nm and 403 nm respectively. It seems that the nature of passivation of surface states affects the position of surface states. Electroluminescence (EL) studies have shown that light emission starts at a threshold and then increases with voltage. Higher EL intensity and lower threshold voltage is obtained in case of smaller particles. The EL spectra of all the samples are found to be broad with peak at about 420 nm. The EL intensity of ZnS:Cu/PVA nanocomposites is much larger than the ZnS:Cu nanoparticles. The high efficiency EL devices for display and lighting can be fabricated using ZnS:Cu nanocomposites with PVA matrix giving violet emission.

Photocatalytic Activity of W-Doped TiO2 Nanopowders

2008 ◽  
Vol 11 (1) ◽  
Author(s):  
Katarzyna A. Michalow ◽  
Andri Vital ◽  
Andre Heel ◽  
Thomas Graule ◽  
Felix A. Reifler ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Dopant Concentration ◽  
Flame Spray ◽  
Titanium Tetra Isopropoxide ◽  
Flame Spray Synthesis ◽  
One Step ◽  
Tio2 Nanopowders ◽  
Doped Titanium Dioxide

AbstractPolycrystalline tungsten-doped titanium dioxide nanopowders within a dopant concentration of 0-1 at.% were prepared by a one-step flame spray synthesis (FSS). Mixtures of titanium tetra-isopropoxide dissolved in ethanol and tungsten hexacarbonyl solubilized in tetrahydrofuran were used as precursors. The specific surface area (SSA) of the powders was between 40 and 130 m

A simple method for producing mesoporous anatase TiO2 nanocrystals with elevated photovoltaic performance

2010 ◽  
Vol 62 (5) ◽  
pp. 223-226 ◽  
Author(s):  
K.P.S. Parmar ◽  
Easwaramoorthi Ramasamy ◽  
Jin Woo Lee ◽  
Jae Sung Lee
Keyword(s):  
Photovoltaic Performance ◽  
Anatase Tio2 ◽  
Tio2 Nanocrystals ◽  
Simple Method

Facile synthesis of rice-like anatase TiO2 nanocrystals

2010 ◽  
Vol 64 (17) ◽  
pp. 1898-1901 ◽  
Author(s):  
Hongrui Peng ◽  
Xuncai Wang ◽  
Guicun Li ◽  
Hongtao Pang ◽  
Xiguang Chen
Keyword(s):  
Anatase Tio2 ◽  
Tio2 Nanocrystals ◽  
Facile Synthesis

scholarly journals Photodetector based on Rutile and Anatase TiO2 nanostructures/n-Si Heterojunction

2021 ◽  
Vol 2114 (1) ◽  
pp. 012025
Author(s):  
S A Hamdan ◽  
I M Ibrahim ◽  
I M Ali
Keyword(s):  
Titanium Dioxide ◽  
Optical Absorption ◽  
Ideality Factor ◽  
Anatase Tio2 ◽  
Optical Absorption Spectra ◽  
Hydrothermal Technique ◽  
Peak Absorption ◽  
Rectification Factor ◽  
Hall Effect Measurements ◽  
Tio2 Nanostructures

Abstract Rutile and anatase titanium dioxide TiO2 nanostructures has been prepared successfully by hydrothermal technique. Also Rutile and anatase TiO2/n-Si heterojunction detector (HJ) has been fabricated. Hall Effect measurements confirmed that prepared films are n-type. The optical absorption spectra showed the prepared films have peak absorption in UV region. TiO2/n-Si heterojunction had exhibited diode-like rectifying I-V behaviour in the dark as well as under the illumination. Ideality factor greater than 2 and rectification factor for Rutile TiO2/n-Si HJ is equal 32.0961 higher than anatase TiO2/n-Si HJ. Photodetetor based on rutile TiO2/n-Si HJ showed higher responsivity and incident photon-to-current efficiency (IPCE) than photodetector based on anatase TiO2/n-Si HJ. Photodetetor based on rutile TiO2/n-Si HJ has responsivity is 69.11Amp/W at 570 nm and IPCE is 21.2%at 370nm and 1.38% at 570nm. For the purpose of investigating the impacts of TiO2 crystal phase upon the performance of the device despite the fact that rutile has a lower band gap compared to anatase, rutile exhibits better photovoltaic activity due to its higher specific surface area.

scholarly journals Reduced Magneli Layers on Anatase TiO2 Nanocrystals Surface Revealed by HAADF STEM Imaging

2020 ◽  
Vol 26 (S2) ◽  
pp. 2674-2676
Author(s):  
Snejana Bakardjieva ◽  
Robert Klie ◽  
Victor Y. Zenou ◽  
Mariana Klementová ◽  
Slavomír Adamec
Keyword(s):  
Anatase Tio2 ◽  
Tio2 Nanocrystals
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