Home Search Collections Journals About Contact us My IOPscience The synthesis of BaMgAl10O17:Eu2+ nanopowder by a combustion method and its luminescent properties This content has been downloaded from IOPscience Please scroll down to see the full text 2011 Adv Nat Sci: Nanosci Nanotechnol 045005 (http://iopscience.iop.org/2043-6262/2/4/045005) View the table of contents for this issue, or go to the journal homepage for more Download details: IP Address: 117.3.66.115 This content was downloaded on 09/10/2013 at 00:32 Please note that terms and conditions apply IOP PUBLISHING ADVANCES IN NATURAL SCIENCES: NANOSCIENCE AND NANOTECHNOLOGY Adv Nat Sci.: Nanosci Nanotechnol (2011) 045005 (4pp) doi:10.1088/2043-6262/2/4/045005 The synthesis of BaMgAl10O17 :Eu2+ nanopowder by a combustion method and its luminescent properties Manh Son Nguyen, Van Tuyen Ho and Nguyen Thuy Trang Pham Department of Physics, College of Sciences, Hue University, 77 Nguyen Hue, Hue, Vietnam E-mail: manhson03@yahoo.com Received 27 April 2011 Accepted for publication 12 September 2011 Published 31 October 2011 Online at stacks.iop.org/ANSN/2/045005 Abstract Europium ion doped BaMgAl10 O17 blue phosphor nanopowder has been fabricated by urea–nitrate solution combustion synthesis at 590 ◦ C for These phosphors were codoped with different europium ion concentrations (1–8 mol%) The experimental results of x-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence showed that the phosphors have a hexagonal single phase structure, the average particle size of the powders was about 50 nm and the emission spectra have a broad band with maximum intensity at wavelength λmax = 455 nm due to transitions from the 4f6 5d1 to the 4f7 electronic configuration of Eu2+ ion The maximum emission of phosphor corresponds to the europium concentration mol% Keywords: phosphor, nanoparticle, combustion, photoluminescence Classification numbers: 4.02, 4.04 synthesis, and also the influence of concentration on emission intensity Introduction BaMgAl10 O17 :Eu2+ blue phosphor has been used extensively in manufacturing tricolor fluorescent lights (FL), field emission displays (FED), plasma display panels (PDPs) and liquid crystal displays (LCD) [1, 2] Emission spectra of BaMgAl10 O17 :Eu2+ phosphor have a broad band with peak at 455 nm due to transition from the 4f6 5d excited state to the 4f7 ground state of ion Eu2+ There are many synthesis technologies of this phosphor [3–6] Every technology has some advantages Among them, combustion synthesis has the following remarkable advantages: low heating temperature and short reaction time However, luminescent properties of materials depend strongly on the technology conditions [2, 7] For BaMgAl10 O17 :Eu2+ phosphors prepared by urea–nitrate solution combustion synthesis, urea plays the role of fuel as well as reducing agent Besides, the initiating combustion temperature influences the product In the present experimental work, we study the influence of urea concentration and the initiating combustion temperature on luminescent properties of BaMgAl10 O17 : Eu2+ phosphors prepared by urea–nitrate solution combustion 2043-6262/11/045005+04$33.00 Experimental Starting materials for the preparation of BaMgAl10 O17 :Eu2+ phosphors by urea–nitrate solution combustion synthesis are a mixture of Ba(NO3 )2 , Mg(NO3 )2 · 6H2 O, Al(NO3 )3 · 9H2 O and Eu2 O3 oxide Urea was used to supply fuel and reducing agent Eu2 O3 oxide has been nitrified by nitric acid The reaction for the formation of BaMgAl10 O17 :Eu2+ , assuming complete combustion, may be written as (1 − x)Ba(NO3 )2 + xEu(NO3 )3 + Mg(NO3 )2 + 10Al(NO3 )3 + 28.34CH4 N2 O → Ba(1−x) Eux MgAl10 O17 + by products [8] Aqueous solution containing stoichiometric amounts of nitrate metal and urea was mixed by a magnetic stirrer and heated at 60 ◦ C for h to gel Next, the gel was dried at 80 ◦ C to dehydrate and combusted at different temperatures within The product was BaMgAl10 O17 :Eu2+ (1 mol%) with white powder The influence of heating temperature and urea concentration on luminescent properties was investigated The samples were prepared with combustion temperature changed © 2011 Vietnam Academy of Science & Technology Adv Nat Sci.: Nanosci Nanotechnol (2011) 045005 M S Nguyen et al 2.0 • : B aM gA l 10 O 17 • • • • 300 • • 70 • • • • • • • •• 1.6 • 1.4 60 1.2 ↓ 200 50 100 40 IPLmax(a u.) Lin (Cps) 1.8 ↓ 400 0.4 30 30 40 50 60 0.8 0.6 20 1.0 0.2 70 θ (D eg ) 0.0 30 Figure XRD diagram of the samples with different concentrations of urea Intensity PL (a u.) (5) • • • • (2) (1) 70 80 • ↓ 1.0 0.5 60 Figure The dependence of maximum emission intensity of Eu2+ ions as a function of urea concentration (1) n = 30 (2) n = 40 (3) n = 50 (4) n = 60 (5) n = 70 (6) n = 80 (3) 1.5 50 Urea concentration, n (mol) 2.0 (4) 40 • • • • • • • • • • • • ↓ (6) 0.0 400 450 500 550 600 650 θ Wavelength (nm) Figure XRD diagram of the samples at different combustion temperatures Figure Emission spectra of phosphors prepared with different concentrations of urea characterized the transition of electronic configuration from the 4f6 d excited state to the 4f7 ground state of Eu2+ ions The emission of the sample with n = 30 has weak luminescent intensity, the emission maximum shifts to a longer wavelength and emission also exists at 617 nm of Eu3+ ions It showed that the low concentration of urea did not suffice for the complete reduction Besides, with n = 80, the luminescent intensity is very low and the position of maximum radiation intensity shifts to a longer wavelength region Figure shows the change of maximum luminescent intensity of the phosphors as a function of urea concentration The phosphor with n = 60 was not only a single-phase structure but also has a better intensity of luminescence than the other samples From the investigated results of the XRD patterns, the invariable concentration of urea were chosen as n = 60 to synthesize the phosphor at different combustion temperatures Their XRD diagrams are presented in figure It shows that samples had a hexagonal single-phase structure when the combustion temperature was at 590 ◦ C At other temperatures, the structure of the materials appeared not only in BaMgAl10 O17 phase but also in another sub-phase Luminescent spectra of the phosphors prepared with variable combustion temperature and constant from 570 to 630 ◦ C, concentration of Eu2+ ions changed from to mol% and changing the urea mole (n urea ) from 30 to 80 times the product mole (n BAM ) For convenience, we set n= in this case 30 n n urea , n BAM 80 Results and discussions 3.1 The effects of combustion technology on the structure and luminescence of BaMgAl10 O17 :Eu2+ blue phosphor The crystallographic phase of phosphor with different urea concentrations at a constant combustion temperature of 590 ◦ C was confirmed by x-ray diffraction (XRD) and the results are shown in figure The XRD pattern indicated that product did not appear at BaMgAl10 O17 phase with n = 30 With n = 40, 50 and 70, products occurred at a low amount of undesirable phase beside the BaMgAl10 O17 phase The material had a hexagonal single phase structure with n = 60 Luminescent spectra of BaMgAl10 O17 :Eu2+ phosphors prepared with different concentrations of urea are shown in figure Emissions of phosphors with concentrations n = 40, 50, 60 and 70 have a broad band with peak at 455 nm that Adv Nat Sci.: Nanosci Nanotechnol (2011) 045005 M S Nguyen et al (1) 570 C (2) 590 C (3) 610 C (4) 630 C (2) 1.5 Intensity PL (a.u) (3) 1.0 (4) (1) 0.5 0.0 350 400 450 500 550 600 650 700 Wavelength (nm) Figure Emission spectra of phosphor with different heating temperatures Figure Emission spectra of BaMgAl10 O17 :Eu2+ with variable Eu2+ ion concentration Intensity PL (a u.) 1.5 1.0 0.5 580 600 620 o Temperature ( C) Figure The dependence of maximum intensity as a function of combustion temperature Figure The plot of emission intensity as a function of Eu2+ ion concentration the radiation of ion Eu2+ in this lattice The change of luminescent intensity of the phosphors BaMgAl10 O17 :Eu2+ on the heating temperature is described in figure The results show that the heated sample at 590 ◦ C had the highest luminescent intensity A SEM image of the samples is shown in figure The average particle size of the powder is about 50 nm However, the particle distribution is not uniform 3.2 The effect of concentration of Eu 2+ ions on luminescent characteristics Phosphors BaMgAl10 O17 :Eu2+ with activator concentration ranging from to mol% were prepared by the combustion of corresponding metal nitrates and urea solution with urea concentration 60 n BAM at 590 ◦ C The prepared phosphors had a single phase structure Luminescent spectra of the phosphors were recorded by exciting at 365 nm and are presented in figure It shows that relative emission intensity increased with increasing activator concentration Eu2+ but the emission maximum did not change Above mol% Eu2+ ion, a sudden drop of relative intensity was observed, probably due to concentration quenching In figure 9, the optimum activator concentration was found to be mol% for maximum emission intensity Figure SEM image of BaMgAl10 O17 urea concentration are presented in figure Broadband luminescent spectra of the samples characterized the transition of Eu2+ ions with maximum luminescent intensity at 455 nm wavelength However, the luminescent spectra also show a low broadband emission with maximum wavelength at 520 nm when the sample was heated at a temperature of 570 ◦ C This suggests that the structure of this phosphor also exists in some unwanted phase, when heating temperature is not appropriate Auxiliary emission band could be Adv Nat Sci.: Nanosci Nanotechnol (2011) 045005 M S Nguyen et al Conclusion References The urea concentration and combustion temperature in the combustion technology influenced the crystalline structure and optical properties of the products BaMgAl10 O17 : Eu2+ phosphor nanopowder was prepared by a urea–nitrate solution combustion method Nanosized blue phosphor BaMgAl10 O17 :Eu2+ had a single hexagonal structure phase that was synthesized with n = 60 and combustion temperature 590 ◦ C Note that the value n = 28.33 was derived from the theoretical calculation in [8] With the increase of Eu2+ concentration, the emission intensity increased but the maximum of the spectra did not change The optimum concentration of Eu2+ ions was mol% in order to achieve the highest emission [1] Yadav R S, Pandey Sh K and Phandey A Ch 2010 Mater Sci Appl 25 [2] Chenm Z and Yan Y 2006 J Mater Sci 40 5793 [3] Jeong Y K, Kim H-J, Kim H G and Choi B-H 2009 Curr Appl Phys 249 [4] Dulda A, Jo D S, Park W J, Masaki T and Yoon D H 2009 J Ceram Process Res 10 811 [5] Won C W, Nersisyan H H, Won H I, Kwon S J, Kim H Y and Seo S Y 2009 J Lumin 678 [6] Lu C-H, Chen C-T and Bhattachrjee B 2006 J Rare Earth 24 706 [7] Chen Z, Yan Y, Liu J, Yin Y, Wen H, Zao J, Liu D, Tian H, Zhang C and Li S 2009 J Alloys Compd 473 L13 [8] Ekambaram S, Patil K C and Maaza M 2005 J Alloys Compd 393 81 ... materials for the preparation of BaMgAl1 0 O1 7 :Eu2 + phosphors by urea–nitrate solution combustion synthesis are a mixture of Ba(NO3 )2 , Mg(NO3 )2 · 6H2 O, Al(NO3 )3 · 9H2 O and Eu2 O3 oxide Urea... emission of phosphor corresponds to the europium concentration mol% Keywords: phosphor, nanoparticle, combustion, photoluminescence Classification numbers: 4. 02, 4.04 synthesis, and also the influence...IOP PUBLISHING ADVANCES IN NATURAL SCIENCES: NANOSCIENCE AND NANOTECHNOLOGY Adv Nat Sci.: Nanosci Nanotechnol (20 11) 045005 (4pp) doi :10. 1088 /20 43- 626 2 /2/ 4/045005 The synthesis of BaMgAl1 0O1 7