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.

scholarly journals Synthesis and Luminescent Properties of Strontium Cerium Oxide Phosphors Doped with Rare Earths

2012 ◽  
Vol 5 (1) ◽  
pp. 1-11 ◽  
Author(s):  
P. R. V. Nannapaneni ◽  
C. A. Rao ◽  
K. V. R. Murthy
Keyword(s):  
Cerium Oxide ◽  
Rare Earths ◽  
Emission Spectra ◽  
Spherical Shape ◽  
Average Crystallite Size ◽  
Luminescent Properties ◽  
Solid State Reaction Method ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Scanning Electron

In this paper we report the synthesis and luminescent properties of Sr2CeO4 doped with rare earths (0.5% concentration of  La, Eu and Dy ions) are reported. The powder samples of rare earths doped strontium cerium oxide (Sr2CeO4: La, Eu and Dy ions) was synthesized by a standard solid state reaction method in air at 12000C. These samples were characterized by X-ray diffraction, scanning electron microscope (SEM) and photoluminescence (PL) techniques, particle size analysis. The XRD data revealed that the structure of the Sr2CeO4 as orthorhombic and the calculated average crystallite size is ~10nm. Scanning electron microscopy revealed that the Sr2CeO4 phosphor particles had non-spherical shape and the irregular shaped particles are highly agglomerated. PL excitation and emission spectra of Sr2CeO4 doped with rare earths are recorded at room temperature. The CIE coordinates depicted on 1931 chart of Eu (0.5%) doped Sr2CeO4 shown that the emission colour varies from blue to white. This phosphor has a good potential for application in white light LEDs.© 2013 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v5i1.10965         J. Sci. Res. 5 (1), 1-11 (2013)

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.

Influence of Preparation Temperature on Performance of Ce1-xPrxO2 Ultrafine Powder Prepared by a Microemulsion Process

2008 ◽  
Vol 368-372 ◽  
pp. 784-786 ◽  
Author(s):  
Jun Yang ◽  
Zhen Feng Zhu ◽  
Jing Ping Li
Keyword(s):  
Crystallite Size ◽  
Calcination Temperature ◽  
Average Crystallite Size ◽  
Ultrafine Powder ◽  
Microemulsion System ◽  
Sem Images ◽  
Preparation Temperature ◽  
Annealing Conditions

A W/O microemulsion system composed of OP-emolsifier / water / cyclohexane / 1-Pentanol was adopted to prepare ultrafine Ce1-xPrxO2 powder via the reaction between the precipitants of cerium and praseodymium salt solved in the nano reactors. The influence of the annealing conditions on the preparation of Ce1-xPrxO2 powder was investigated. It was shown that, with the increase of calcination temperature from 400 °C to 800 °C, the average crystallite size of the particles increases from 9.5 nm to 25.8 nm. FE-SEM images showed that shape of the particles is layered and sheet-like.

scholarly journals Effect of calcination temperature and calcination time on the kaolinite/tio2 composite for photocatalytic reduction of CO2

2012 ◽  
Vol 58 (4) ◽  
pp. 10-22 ◽  
Author(s):  
Martin Reli ◽  
Kamila Kočí ◽  
Vlastimil Matějka ◽  
Pavel Kovář ◽  
Lucie Obalová
Keyword(s):  
Crystallite Size ◽  
Physical Adsorption ◽  
Photocatalytic Reduction ◽  
Thermal Hydrolysis ◽  
Calcination Time ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Titanyl Sulphate ◽  
Reduction Of Co2 ◽  
Hydrolysis Of

Abstract The kaolinite/TiO2 composite (60 wt% of TiO2) was prepared by thermal hydrolysis of a raw kaolin suspension in titanyl sulphate and calcined at different temperatures (600, 650 and 700°C) and for different times (1, 2 and 3 h). The obtained samples were characterized by XRPD, N2 physical adsorption and SEM, and tested for photocatalytic reduction of CO2. The different calcination conditions did not influence TiO2 phase composition, only slightly changed the specific surface area, and significantly affected crystallite size of kaolinite/TiO2 composite. A higher temperature and longer duration of calcination lead to higher crystallinity of the powder. The photocatalytic results showed that the crystallite size determined the efficiency of kaolinite/TiO2 photocatalysts.

The Effect of Different Methods to Pretreat Reed Pulp on the Crystallinity of Microcrystalline Cellulose

2014 ◽  
Vol 1056 ◽  
pp. 12-15 ◽  
Author(s):  
Wen Long Zhang ◽  
Wen Long Zhao ◽  
Ya Jie Dai
Keyword(s):  
Crystallite Size ◽  
Microcrystalline Cellulose ◽  
Average Crystallite Size ◽  
Comprehensive Analysis ◽  
Raw Material ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimethyl Acetamide ◽  
Crystal Type

Reed Pulp was Raw Material that Pretreated by Four Methods {ultrasonic, Microwave, N, N-Dimethyl Acetamide (DMAc) and Tetrahydrofuran (THF)}. Reed Microcrystalline Cellulose (MCC) was Prepared by the Dilute Hydrochloric Acid Hydrolysis from Pretreated Reed Pulp. the Influences of Pretreatment Methods on Crystalline Type, Crystallinity and Crystallite Size of MCC were Investigated by X-Ray Diffraction (XRD). the Results Showed that the Crystallinity of MCC with Four Pretreatment Methods was 68.45%, 62.28%, 63.21% and 69.56%, Respectively. the Average Crystallite Size of MCC Prepared by Hydrolysis after Pretreated by Dmac was the Largest. whereas, the Crystal Type of MCC was Not Changed, it was still the Cellulose Type I. Comprehensive Analysis Indicated that the Effects of MCC Prepared by Hydrolysis after Pretreated by Ultrasonic were the Best.

scholarly journals Structural and Magnetic Properties of Co‒Mn Codoped ZnO Nanoparticles Obtained by Microwave Solvothermal Synthesis

Crystals ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 410 ◽  
Author(s):  
Jacek Wojnarowicz ◽  
Myroslava Omelchenko ◽  
Jacek Szczytko ◽  
Tadeusz Chudoba ◽  
Stanisław Gierlotka ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Crystallite Size ◽  
Doping Level ◽  
Solvothermal Synthesis ◽  
Zinc Acetate Dihydrate ◽  
Average Particle Size ◽  
Average Crystallite Size ◽  
Average Particle ◽  
Acetate Tetrahydrate ◽  
Preparation Methods

Zinc oxide nanoparticles codoped with Co2+ and Mn2+ ions (Zn(1−x−y)MnxCoyO NPs) were obtained for the first time by microwave solvothermal synthesis. The nominal content of Co2+ and Mn2+ in Zn(1−x−y)MnxCoyO NPs was x = y = 0, 1, 5, 10 and 15 mol % (the amount of both ions was equal). The precursors were obtained by dissolving zinc acetate dihydrate, manganese (II) acetate tetrahydrate and cobalt (II) acetate tetrahydrate in ethylene glycol. The morphology, phase purity, lattice parameters, dopants content, skeleton density, specific surface area, average particle size, average crystallite size, crystallite size distribution and magnetic properties of NPs were determined. The real content of dopants was up to 25.0% for Mn2+ and 80.5% for Co2+ of the nominal content. The colour of the samples changed from white to dark olive green in line with the increasing doping level. Uniform spherical NPs with wurtzite structure were obtained. The average size of NPs decreased from 29 nm to 21 nm in line with the increase in the dopant content. Brillouin type paramagnetism and an antiferromagnetic interaction between the magnetic ions was found for all samples, except for that with 15 mol % doping level, where a small ferromagnetic contribution was found. A review of the preparation methods of Co2+ and Mn2+ codoped ZnO is presented.

Effect of reaction temperature on the average crystallite size of SexTe1−x alloys

1986 ◽  
Vol 1 (2) ◽  
pp. 234-236 ◽  
Author(s):  
Santokh S. Badesha ◽  
George T. Fekete ◽  
Ihor Tarnawskyj
Keyword(s):  
Crystallite Size ◽  
Small Particle ◽  
Chemical Method ◽  
Average Crystallite Size ◽  
Organic Media ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electrophotographic Properties ◽  
Dark Decay ◽  
Chalcogenide Materials

Electrophotographic properties of chalcogenide materials are readily influenced by altering their composition and/or structure. Dark decay and cycle down of photoreceptors utilizing small particle generators are both directly proportional to average crystallite size (ACS). This paper describes a novel chemical method to control the ACS of Se, Te, and Sex Te1−x alloys. These chalcogenide materials are prepared as powders by the reduction or coreduction of SeIV and/or TeIV intermediates with hydrazine, in organic media. To control the ACS of precipitated chalcogens the reaction is carried out at the desired temperature. X-ray diffraction measurements are used to determine the ACS, homogeneity, and phase of these precipitated powders.

Oxygen bombardment effects on average crystallite size of sputter-deposited ZnO films

2008 ◽  
Vol 354 (17) ◽  
pp. 1926-1931 ◽  
Author(s):  
Mamoru Furuta ◽  
Takahiro Hiramatsu ◽  
Tokiyoshi Matsuda ◽  
Chaoyang Li ◽  
Hiroshi Furuta ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Average Crystallite Size ◽  
Zno Films ◽  
Sputter Deposited

scholarly journals Structural, electrical and magnetic behaviour of undoped and nickel doped nanocrystalline bismuth ferrite by solution combustion route

2015 ◽  
Vol 9 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Kakali Sarkar ◽  
Soumya Mukherjee ◽  
Siddhartha Mukherjee
Keyword(s):  
Crystallite Size ◽  
Bismuth Ferrite ◽  
Structural Phase ◽  
Average Crystallite Size ◽  
Magnetic Behaviour ◽  
Solution Combustion ◽  
Chemical Route ◽  
Structural Formation ◽  
Xrd Diffraction ◽  
The Matrix

Multiferroic bismuth ferrite (BFO) and Ni-doped bismuth ferrites, with perovskite structure, were synthesized by chemical route at the temperatures ranging from 500 to 600 ?C in controlled atmosphere. The structural phase analysis of materials was identified by XRD and crystallite size was calculated from the half width measurement of the well defined major XRD diffraction peak. Average crystallite size was calculated by applying Scherrer?s formula and found to have values in the range from 14 to 35 nm. FESEM was used to evaluate the morphology and structural formation of nanocrystallite grains, while EDX confirmed elemental composition including the presence of dopant in the matrix. Dielectric properties and effect of electric field on polarization behaviour were studied for both undoped and Ni-doped BFO. Doping shows a clear change in ferroelectric behaviour. Antiferromagnetic nature of bulk bismuth ferrite transforms to superparamagnetic strong ferroelectric nature for both undoped and nickel doped nanocrystalline bismuth ferrite due to its close dimension of crystallite size with magnetic domains leading to break-down of frustrated spin cycloidal moment. The superparamagnetism behaviour is more pronounced for the nickel doped BFO though magnetic saturation is slightly higher for the undoped nanocrystalline bismuth ferrite.

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