scholarly journals Effect of Eu3+ Concentration on Luminescence Studies of Y4Al2O9 Phosphor

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Vikas Dubey ◽  
Sadhana Agrawal ◽  
Jagjeet Kaur
Keyword(s):  
Large Scale ◽  
Light Emission ◽  
Red Light ◽  
Average Crystallite Size ◽  
Solid State Reaction Method ◽  
Inorganic Materials ◽  
Europium Oxide ◽  
Prepared Phosphor ◽  
Scale Production ◽  
Display Devices

The present paper reports the effect of europium concentration on photoluminescence (PL) and thermoluminescence (TL) studies of Eu3+ doped Y4Al2O9 phosphor using inorganic materials like yttrium oxide (Y2O3), aluminium oxide (Al2O3), boric acid (H3BO3) as a flux, and europium oxide (Eu2O3). The sample was prepared by the modified solid state reaction method, which is the most suitable for large-scale production. The prepared phosphor sample was characterized using X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEGSEM), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), thermoluminescence (TL), and CIE techniques. The PL emission was observed in the range of 467, 535, 591, 611, 625, and 629 nm for the Y4Al2O9 phosphor doped with Eu3+ (0.1 mol% to 2.5 mol%). Excitation spectrum was found at 237 and 268 nm. Sharp peaks were found around 591, 611, and 625 nm with high intensity. From the XRD data, using Scherer’s formula, the calculated average crystallite size of Eu3+ doped Y4Al2O9 the phosphor is around 55 nm. Thermoluminescence study was carried out for the phosphor with UV irradiation. The present phosphor can act as single host for red light emission in display devices.

Luminescence Studies of Eu3+ Doped Calcium Bromofluoride Phosphor

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Jagjeet Kaur ◽  
Yogita Parganiha ◽  
Vikas Dubey
Keyword(s):  
Rare Earth ◽  
Light Emission ◽  
Red Light ◽  
Broad Band ◽  
Solid State Reaction Method ◽  
Glow Peak ◽  
Prepared Phosphor ◽  
Excitation Spectra ◽  
Display Devices ◽  
Rare Earth Doped

The present paper reports photoluminescence (PL) and thermoluminescence (TL) properties of rare earth-doped calcium bromo-fluoride phosphor. The europium (Eu3+) was used as rare earth dopant. The phosphor was prepared by Solid state reaction method (conventional method). The PL emission spectrum of the prepared phosphor shows intense peaks in the red region at 611 nm for 5D0→7F2 transitions, and the PL excitation spectra show a broad band located around 220–400 nm for the emission wavelength fixed at 470 nm. The TL studies were carried out after irradiating the phosphor by UV rays with different exposure time. The glow peak shows second-order kinetics. The present phosphor can act as host for red light emission in display devices.

scholarly journals Facile and Novel in-Plane Structured Graphene/TiO2 Nanocomposites for Memory Applications

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
E. M. Shehata ◽  
M. M. Ibrahim ◽  
M. R. Balboul
Keyword(s):  
Thin Films ◽  
Large Scale ◽  
Low Cost ◽  
Charge Trapping ◽  
Average Crystallite Size ◽  
Rietveld Analysis ◽  
Scale Production ◽  
Simple Strategy ◽  
Large Scale Production ◽  
Memory Applications

Here, we report a simple strategy for the preparation of graphene/TiO2 nanocomposite by UV-assisted incorporation of TiO2 nanosol in graphene oxide (GO) dispersion. The proposed method is facile and of low cost without using any photocatalysts or reducing agents; this can open up a new possibility for green preparation of stable graphene dispersions in large-scale production. X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy (TEM) have been used to characterize carefully the as-prepared composites and to confirm the successful preparation of the nanocomposites. The average crystallite size of TiO2 nanoparticles calculated from XRD pattern using Rietveld analysis is ~35 nm. TEM measurements show the adsorption of TiO2 onto graphene (G) sheets, which prevents the restacking of graphene sheets. Current-voltage and capacitance-voltage measurements were used to investigate the electrical resistive memory properties of GO, GO/TiO2, and G/TiO2 thin films. Observed results show hysteresis behavior due to the charge trapping and detrapping process, indicating that the prepared thin films exhibit an excellent resistance switching memory characteristic for G/TiO2 device.

scholarly journals Thermoluminescence and Photoluminescence Study of Erbium Doped CaY2O4 Phosphor

2015 ◽  
Vol 2015 ◽  
pp. 1-5 ◽  
Author(s):  
Vikas Dubey ◽  
Ratnesh Tiwari ◽  
Raunak Kumar Tamrakar ◽  
Chandrabhushan Markande ◽  
Gajendra Singh Rathore ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Exposure Time ◽  
Glow Curve ◽  
Emission Spectra ◽  
Average Crystallite Size ◽  
Solid State Reaction Method ◽  
Uv Exposure ◽  
Prepared Phosphor ◽  
Temperature Peak ◽  
Higher Temperature

Phosphor doped with erbium ion with variable concentration (0.5–2 mol%) was synthesized by solid state reaction method. CaY2O4:Er3+ phosphor is characterized by X-ray diffraction technique for structural analysis and crystallite size calculation. Average crystallite size was found to be nearly 58 nm. Two prominent TL glow peaks found at 163°C associated with higher temperature peak 340°C. The peak intensity of higher temperature (340°C) peak was less as compared to lower temperature peak (163°C) because the deep trapping formation is less in case of UV irradiation. Sample shows good TL glow curve and for variable UV exposure time maximum TL intensity was found at 20 min UV exposure which is optimized UV exposure time. Sample was studied by photoluminescence emission spectra excited by xenon flash lamp with nearly 360 nm and four prominent peaks found at wavelengths 445, 525, 553, and 565 nm; here the 445 and 565 nm peak were intense as compared to others. From the PL emission spectra, it is concluded that the color tenability of prepared CaY2O4:Er3+ was blue-green and it is verified by CIE coordinate. Kinetic parameters of prepared phosphor were calculated by computerized glow curve deconvolution (CGCD) technique.

Synthesis and characterization of Y2O3: Eu3+ powder phosphor by a hydrolysis technique

1998 ◽  
Vol 13 (10) ◽  
pp. 2950-2955 ◽  
Author(s):  
Yong Dong Jiang ◽  
Zhong Lin Wang ◽  
Fuli Zhang ◽  
Henry G. Paris ◽  
Christopher J. Summers
Keyword(s):  
Electron Microscopy ◽  
Large Scale ◽  
Luminescent Properties ◽  
Industrial Applications ◽  
Europium Oxide ◽  
Scale Production ◽  
Experimental Conditions ◽  
Luminescence Efficiency ◽  
Transmission Electron ◽  
Large Scale Production

A forced hydrolysis technique is used for preparing Y2O3: Eu3+ powders at low processing temperatures. The technique uses yttrium oxide, europium oxide, and nitric acid and urea, and has the potential for large-scale production for industrial applications. Several experimental conditions have been examined to optimize the luminescence efficiency. The best result was found to be at 2 mol% Eu doping and a 2 h firing of 1400 °C. Microstructural information provided by x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) have been applied to interpret the observed luminescent properties.

Enhanced Red Emission in Lithium Doped CaWO4:Eu3+ and CaMoO4:Eu3+ Phosphor

2007 ◽  
Vol 561-565 ◽  
pp. 1081-1084
Author(s):  
Shi Kao Shi ◽  
Jing Gao ◽  
Ji Zhou
Keyword(s):  
Light Emission ◽  
Red Light ◽  
Energy Transition ◽  
Luminescent Properties ◽  
Solid State Reaction Method ◽  
Short Wave ◽  
Excitation Spectra ◽  
Lithium Ions ◽  
Xrd Patterns ◽  
Dipole Energy

The lithium ions doped red-emitting phosphors of (Ca,Eu)WO4 and (Ca,Eu)MoO4 were synthesized by solid-state reaction method, and their luminescent properties were investigated. The XRD patterns show that the phosphors are isostructural and share a tetragonal scheelite structure, even some lithium ions are doped. The excitation spectra consist of broad charge transfer bands in the short-wave UV region of W6+→O2- and Eu3+→O2- with three sharp lines around 395, 465 and 535 nm of the Eu3+ 4f excitation transitions. The characteristic emissions of WO4 2- and MoO4 2- are quenched absolutely and red light emission of Eu3+ exhibits predominate peak around 615 nm due to the electric dipole energy transition of 5D0→7F2. Excited with 395 nm, the evident enhanced emission of the phosphors were observed when Li+ doped in the host, which implies that the addition of some Li+ is beneficial for the energy transfer from WO4 2- or MoO4 2- to Eu3+.

scholarly journals Synthesis and luminescent properties of uniform monodisperse LuPO 4 :Eu 3+ /Tb 3+ hollow microspheres

2017 ◽  
Vol 4 (12) ◽  
pp. 171451 ◽  
Author(s):  
Yu Gao ◽  
He Yu ◽  
Cheng Shi ◽  
Guiyan Zhao ◽  
Yanfeng Bi ◽  
...  
Keyword(s):  
Large Scale ◽  
Exchange Process ◽  
Scale Up ◽  
Luminescent Properties ◽  
Inorganic Materials ◽  
Hollow Microspheres ◽  
Scale Production ◽  
Simple Method ◽  
Synthetic Process ◽  
Ion Exchange Process

Uniform monodisperse LuPO 4 :Eu 3+ /Tb 3+ hollow microspheres with diameters of about 2.4 µm have been successfully synthesized by the combination of a facile homogeneous precipitation approach, an ion-exchange process and a calcination process. The possible formation mechanism for the hollow microspheres was presented. Furthermore, the luminescence properties revealed that the LuPO 4 :Eu 3+ and LuPO 4 :Tb 3+ phosphors show strong orange-red and green emissions under ultraviolet excitation, respectively, which endows this material with potential application in many fields, such as light display systems and optoelectronic devices. Since the synthetic process can be carried out at mild conditions, it should be straightforward to scale up the entire process for large-scale production of the LuPO 4 hollow microspheres. Furthermore, this general and simple method may be of much significance in the synthesis of many other inorganic materials.

Luminescence Properties of (MxMg1-x)2SiO4:Dy3+, Eu3+ (M=Ca, Sr, Ba)

2010 ◽  
Vol 105-106 ◽  
pp. 827-829
Author(s):  
Da Wei He ◽  
Xin Rong Zhou ◽  
Yong Sheng Wang
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Light Emission ◽  
Red Light ◽  
Solid State Reaction Method ◽  
Excitation Spectra ◽  
Reaction Method ◽  
Violet Light ◽  
Uv Excitation ◽  
Emission Light

A series of phosphor of (MxMg1-x)2SiO4: Dy3+, Eu3+ (M=Ca, Sr, Ba) were synthesized by high temperature solid-state reaction method and studied. The structure and emission spectrum excited by near violet light were investigated. The excitation spectra of single-doped (MxMg1-x)2SiO4: Dy3+ show strong absorption near 322nm, 347nm, 362nm and 391nm due to 6H15/2→4I9/2, 6H15/2→6P5/2, 6H15/2→4F7/2, 6H15/2→4G11/2 transition of Dy3+. The emission light is at about 469nm, 474nm, 483nm and 494nm under 391nm UV excitation. In order to obtain white light emission, (MxMg1-x)2SiO4: Dy3+, Eu3+ (M=Ca, Sr, Ba) were prepared to enhance the red light emission.

AGRICULTURAL PRODUCTION OF CA DONG PEOPLE IN RESETTLEMENT AREA OF TRANH RIVER HYDROPOWER NUMBER 2: CURRENT SITUATION AND IMPACT FACTORS

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Bùi Thị Bích Lan
Keyword(s):  
Social Relations ◽  
Agricultural Production ◽  
Large Scale ◽  
Transition Process ◽  
Impact Factors ◽  
Small Scale ◽  
Scale Production ◽  
Technical Application ◽  
Production Models ◽  
Role Of The State

In Vietnam, the construction of hydropower projects has contributed significantly in the cause of industrialization and modernization of the country. The place where hydropower projects are built is mostly inhabited by ethnic minorities - communities that rely primarily on land, a very important source of livelihood security. In the context of the lack of common productive land in resettlement areas, the orientation for agricultural production is to promote indigenous knowledge combined with increasing scientific and technical application; shifting from small-scale production practices to large-scale commodity production. However, the research results of this article show that many obstacles in the transition process are being posed such as limitations on natural resources, traditional production thinking or the suitability and effectiveness of scientific - technical application models. When agricultural production does not ensure food security, a number of implications for people’s lives are increasingly evident, such as poverty, preserving cultural identity, social relations and resource protection. Since then, it has set the role of the State in researching and building appropriate agricultural production models to exploit local strengths and ensure sustainability.

I. S. A. Baud. Forms of Production and Women's Labour: Gender Aspects of Industrialisation in India and Mexico. New Delhi: Sage Publications. 1992. 321 pp.Hardbound. Price: Indian Rs 295.00.

1993 ◽  
Vol 32 (1) ◽  
pp. 129-131
Author(s):  
Naureen Talha
Keyword(s):  
Large Scale ◽  
Indian Society ◽  
New Delhi ◽  
Scale Production ◽  
Female Labour ◽  
Self Employment ◽  
Commodity Production ◽  
Large Scale Production ◽  
Mexican Society ◽  
Small Production

The literature on female labour in Third World countries has become quite extensive. India, being comparatively more advanced industrially, and in view of its size and population, presents a pictures of multiplicity of problems which face the female labour market. However, the author has also included Mexico in this analytical study. It is interesting to see the characteristics of developing industrialisation in two different societies: the Indian society, which is conservative, and the Mexican society, which is progressive. In the first chapter of the book, the author explains that he is not concerned with the process of industrialisation and female labour employed at different levels of work, but that he is interested in forms of production and women's employment in large-scale production, petty commodity production, marginal small production, and self-employment in the informal sector. It is only by analysis of these forms that the picture of females having a lower status is understood in its social and political setting.

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