Influence of lithium on structure and optical properties of lanthanum dopedyttrium oxide thin filmsJ.R. Jayaramaiaha,⁎, R. Shamanthb, V. Jayanthc, B.N. Lakshminarasappad, K.R. Nagabhushanae,R.S. Gedamf
a Department of Physics, Government First Grade College, Tiptur 572 201, IndiabDepartment of ECE, Vijaya Vittala Institute of Technology, Bangalore 560 077, Indiac Department of ME, Siddaganga Institute of Technology, Tumkur 572103, Indiad Institue of Physics, Federal University of Mato Grosso do Sul, Campo Grande, MS CEP 79070 – 900, Brazile Postgraduate Program in Interdisciplinary Health Science, Federal University of São Paulo, Campus Baixada Santista, CEP: 11070-100 Santos, SP, BrazilfDepartment of Physics, Visvesvaraya National Institute of Technology, Nagpur 440 010, India
G R A P H I C A L A B S T R A C T
Influence of lithium on structure and optical properties of lanthanum doped yttrium oxide thin films.
Luminescence emission of lithium incorporated lanthanum doped yttrium oxide thin films are studied. The filmswere prepared by spray pyrolysis method at °C. The crystallites sizes were evaluated and found to be ~50 nmfrom the X-ray diffraction peak. The feature of surface morphology was obtained by field emission scanningelectron microscope. Fourier transformed infrared spectrum represent absorption peak is at 875 cm−1. Opticalabsorption peak at 260 nm reveals the red shift in Li doped samples with energy gap 5.42 eV. Photoluminescenceemissions are at 317, 390, 428 and 612 nm. Gamma-irradiated films shows TL glow peaks at 465 K and 588 Kand their corresponding activation energies and the frequency factors were found to be 0.56 eV, 1.1 MHz and0.6 eV, 0.3 MHz respectively. The incorporated Li ions played a vital role to decrease the processing temperaturewith the improved the morphological features.
https://doi.org/10.1016/j.inoche.2020.108098Received 24 April 2020; Received in revised form 16 June 2020; Accepted 6 July 2020
Incitement of sodium ions on structural and optical properties ofdysprosium doped neodymium oxide
J.R. Jayaramaiah a,⁎, V. Jayanth b, R. Shamanth c, R.S. Gedam d, K.R. Nagabhushana e, Sonia H. Tatumi e
a Department of Physics, Government First Grade College, Tiptur 572 201, Indiab Department of Mechanical Engineering, Siddaganga Institute of Technology, Tumkuru 572 103, Indiac Department of Electronics and Communication Engineering, VVIT, Bangalore 560 077, Indiad Department of Physics Visvesvaraya, National Institute of Technology, Nagpur 440 010, Indiae Postgraduate Program in Interdisciplinary Health Science, Federal University of São Paulo, Campus Baixada Santista, CEP 11070-100 Santos, SP, Brazil
a b s t r a c ta r t i c l e i n f o
Article history:Received 30 April 2020Received in revised form 16 June 2020Accepted 18 June 2020Available online 19 June 2020
Luminescence reveals fromnano gravel crimps of sodium ion incorporated dysprosiumdoped neodymiumoxidehave been synthesized by the solution combustion method. A-type hexagonal crystalline structure is recognizedby powder X-ray diffraction. Visual surface morphology features of nano gravels are analyzed by the field emis-sion scanning electron microscopy. Energy dispersive X-ray spectroscopy approved the existence of Na, Nd, O, Cand Dy elements. X-ray photoelectron spectroscopy data describes the binding energy signature of elements en-sued in the sample as Nd 4d5/2, 4p3/2, 3d5/2, 3d3/2, O 1s, C 1s, Na 1s, and Dy 4d. The diffused reflectance spectrumanalysis is used to estimate the optical energy gap. Fourier transformed-infrared spectrum recognized Nd\\Obond. Raman spectrum peaks are assigned to Fg and combination of Ag+ Egmodes and it describes A-type hex-agonal crystalline phase of the sample. Photoluminescence emissions are observed in the region of blue and redas deconvoluted emission peaks at 323, 375, 438, 492, 542, 623, 665, 690 and 743 nm. Thermoluminescence glowpeaks explored as 100 °C and 180 °Cwith the respective activation energies and the frequency factors are 1.33 eV,97 MHz and 0.325 eV, 4.2 kHz.
1. Introduction
Nanoscale materials are the prime hubs of nanoscience and nano-technology. Science and technology of nanostructure is an interdisci-plinary with a wide area of research and development. The researchand developmental growth is spread across the globe for recent de-cades. A nanometer is one billionth of a meter and it is around one hun-dred thousand (105) times smaller than the size of a human hair.Nanoscience is a study of materials at atomic or molecular scales,though nanotechnology is a strategy, characterization, production andapplication under a control in shape and size of materials at nanometerscale. Nanomaterials are emerged by the unique properties of optical,electrical, magnetic and with others. The emerged stuffs will have agreat impression on potentiality of field in electronics, optical, mechan-ical, medicine and others [1–4]. Significant changes in electrical and op-tical characteristics at nanoscale materials, is a basis of quantum effectsfor high surface to volume ratio. This fact increases the energy gap asthere is decrease in number of admissible quantum states, improvessurface area and interfacial effects at nanoregime [5]. Nanomaterialsdraw a great attention due to the electronic and optical properties.
Among the various nanomaterials, luminescent materials have been in-vestigated because of their major properties are differ from the bulk dy-namically [6]. Thus, a research on effective and low cost phosphors is apuzzling problem for new luminescent materials [7,8].
The rare earth (RE) oxides are much research representative due totheir low lasing threshold, high luminescent performance, drug trans-port vehicle, magnetic resonance imaging, catalysts and time resolvedfluorescence, biological detection labels and so on [9]. Incorporated REions in glasses are having superior physical and chemical behaviorslike hardness, elasticity, thermal stability, chemical stability and so onfor more field strength than the traditional network modifier cat ions[10,11]. RE sesquioxide are extensive tenders in display plans, solidstate lasers, X-ray radiography and luminescent materials. These mate-rials show a stable host for powerful lasers, high chemical stability, ther-mal stability and maximum power output. RE sesquioxide ofneodymium oxide (Nd2O3) nanostructure crystalline materials are C-type cubic phase and A-type hexagonal phase. The crystalline phasesdepend on the ionic radii of RE ion, C-type cubic phase is formed bysmaller cat-ions and A-type hexagonal phase is formed by longer cat-ions [12–14]. Nd2O3 has high dielectric constant, high thermal stabilityand energy gap (4.7 eV), these aspects are useful for considering as agate material in CMOS and for designing innovative devices to leadover SiO2 [15–18]. Nd2O3 assimilated glasses have an excellent optical
Impact of Na2-EDTA and urea on structure and optical properties of pure neodymium oxide
J.R. Jayaramaiah a,*, V. Jayanth b, R. Shamanth c, K.R. Nagabhushana d, B. Marappa e, Sonia H. Tatumi d
a Department of Physics, Government First Grade College, Tiptur, 572 201, India b Department of Mechanical Engineering, Siddaganga Institute of Technology, Tumkuru, 572 102, India c Department of Electronics and Communication, Vijaya Vittala Institute of Technology, Bangalore, 560 077, India d Postgraduate Program in Interdisciplinary Health Science, Federal University of S~ao Paulo, Campus Baixada Santista, CEP 11070-100, Santos/SP, Brazil e Department of Physics, Sree Siddaganga Women College, Tumakuru, 572 102, India
Nano pebbles of pure neodymium oxide is synthesized by the solution combustion method and they exhibit room temperature photoluminescence and thermoluminescence properties. Powder X-ray diffraction pattern reveals A- type hexagonal structure. Surface morphology is visualized by the field emission scanning electron microscopy. The visualized images are regular and irregular shapes with smooth surface. Energy dispersive X-ray spectros-copy reveals the existence of Nd, O and Na elements. X-ray photoelectron spectroscopy reveals the signature of all elements exist in the sample. The diffused reflectance spectrum is used to evaluate the optical band gap energy. Fourier transformed-infrared spectrum confirms the existence of Nd and O bond. Raman spectrum peaks are assigned and confirms A-type hexagonal phase. PL emission is observed in UV, blue, green and red region and the peaks are located at 325, 347, 380, 385, 422, 445, 485, 530, 605, 625, 650, 690 and 750 nm. The activation energies and the frequency factors of thermoluminescence are calculated. The synthesized Nd2O3 is a promising material for white light emitting diodes and the supra linearity features of TL is to be a potential candidate for dosimeters applications.
1. Introduction
Nanotechnology is a ground breaking research area of science. Ma-terials of nanoscale are in the order of nanometer, 1 nm comprises a ten hydrogen atoms placed in a row and it ranges much smaller than the length of bacteria or an animal cell. A material is to be treated as nano if at least one of the dimensions is less than 100 nm. Shape dimensions such as thin films (2D), wires (1D) and spherical particles (0 D) are involved in this classification. The unique properties of nanoparticles are optical, magnetic, electrical and others are emerged. These emerged properties are having great potential and high impact on electronics, medicine along with other related fields [1,2]. Thermal, electrical, structural, magnetic, optical and dielectric properties of nanomaterials are much different from the bulk material due to quantum confinement effect. Quantum confinement effect will lead in huge advances in luminescence area, digital memory storage, image processing, optical telecommunications, photonics and so on [3–6]. The shape and size
factors are momentous at nanoscale for physical and chemical proper-ties. Shape monitored synthesis of nanoparticles is a strategy point for different morphology. The morphology will worth on electronic, optical and magnetic properties in comparison with the earlier one [7,8]. The atoms or molecules are localized at the nanoscale surface. The surface atoms or molecules are capable to move easier at low temperature. Easier movement of atoms or molecules are the cause of decrease the melting point of nanoscale materials in comparision with the bulk [9]. Nanoscale metal oxides find useful applicants in solar cell, fuel cell, wastewater treatment, anti-bacterial activities, gas sensor, hydrogen storage and generation and so on [10].
Rare earth (RE) compounds are attractive due to their characteristic features originating from a partially shielded 4f-orbital [11,12]. Neo-dymium (Nd) element of lanthanide series has wide applications in various areas such as luminescent displays, magnetic devices, catalysts, dielectrics, protective coatings etc. Transition within a well-protected inner shell makes an independent absorption of the surrounding atoms
Structural elucidation and optical analysis on europium dopedcadmium sulphide nano thin films
J.R. Jayaramaiaha,*, V. Jayanthb, R. Shamanthc
aDepartment of Physics, Government First Grade College, Tiptur, 572 201, IndiabDepartment of Mechanical Engineering, S.I.T. Tumkur, 572 103, IndiacDepartment of E.C.E, Vijayavittala Institute of Technology, Bangalore, 560 077, India
Blue shift presentation of nanostructured europium doped cadmium sulphide thin films aregrownup by spray pyrolysis. The films are valuable applications for solar cell as a window ma-terial and luminescent phosphor. Glancing angle X-ray peaks are indexed with reference toJCPDS No. 061-0314. X-ray peaks are witness for hexagonal polycrystalline of cadmium sulphide.Field emission scanning electron microscopy image of the film are in spherical structures withdifferent sizes are in compact. Optical absorption spectrum peak at 485 nm reveals the blue shiftdue to the quantum confinement effect. Frequency shifts and asymmetry of the spectrum isanalyzed by Raman spectroscopy. Peaks are at 302 cm−1 and 603 cm−1 are the longitudinaloptical phonons. Elemental binding energy like Cd 3d, S 2p, C 1s, O 1s and Eu 3d are analyzed byX-ray photoelectron spectroscopy. Photoluminescence emission peaks are at 488 nm 732 nm.
1. Introduction
Nanotechnology is the promising mode for the development of science and nano-scale devices. Physical, optical, electrical andchemical properties are different from their bulk counter parts. Nano-structured materials are potential applications in various fieldsviz. electronics, solar photovoltaic, biotechnology, medicine and so on [1]. Quantum confinement effect is the root cause for thenovel physical and chemical properties in thin films [2]. Quantum dots are the responsible for large absorption coefficient, largeextinction coefficient, tuneable band structure and high dipole moment. Sensitizing solar cell devices on photovoltaic applications insolar energy conversion is due to quantum dot [3]. Exhaust of fossil fuels, global warming by discharge of carbon dioxide, economydevelopment and indispensable usage of energy. Solar energy is the free supply of energy mode. Exploration of sustainable solarenergy for the global energy crisis has become a research motivation. To frame much use of solar energy is a very well choice toresolve energy crisis and ecofriendly problems. For increase the efficiency and reduce the cost of solar energy, solar cells have beenextensively explored. Thin film solar cells are outstanding potential in low cost. Polycrystalline cadmium sulphide (CdS) thin filmsolar cells are efficient and low cost [4].
Nano thin films of broad absorption and symmetric emission for better photo stability than traditional fluorescent labels [5–7].Different applications are LED, lasers and biological labels [8–11]. Doped nano-scale semiconductors are research focus for per-ceptible merits, such as larger collective Stokes shift to reduce self-quenching and inattentiveness to thermal and photochemicaldisturbances [12]. Rare earth doped nano-phase semiconductors are turns the electronic, optical, mechanical, magnetic propertiesand luminescent properties [13–15]. CdS is one of the binary (II-VI) semiconductors and its thin film form is highly transmission and
https://doi.org/10.1016/j.ijleo.2019.164079Received 20 August 2019; Received in revised form 15 December 2019; Accepted 16 December 2019
a Department of Physics, Government First Grade College, Nargund, 582 207, Indiab Department of Physics, PES University, BSK III Stage, Bangalore 560 085, Indiac Department of Physics, J.B. Campus, Bangalore University, Bangalore 560 056, India
a r t i c l e i n f o
Article history:Received 5 August 2016Received in revised form28 November 2016Accepted 29 November 2016Available online 7 December 2016
Lithium ions incorporated samarium doped yttrium oxide nanostructured thin films are prepared byspray pyrolysis. Glancing angle X-ray diffraction spectrum reveals the phase and crystallinity of thefilm. The crystallites sizes are found to be ∼50 nm. Surface morphology of the film is studied using fieldemission scanning electron microscope. The image appears as carved sculptures of particles with agglom-eration. Fourier transformed infrared spectrum shows a sharp and wide absorption peak at 875 cm−1.Optical absorption spectrum exhibits a prominent absorption peak at 270 nm and the correspondingenergy gap is found to be ∼5.53 eV. A broad photoluminescence emission is observed in the range560–690 nm with a peaks at 595, 608 and 622 nm and shoulders at 580, 645 and 662 nm. The filmsare irradiated with �-rays in a dose range 187–563 Gy. Thermoluminescence glow curve is deconvolutedinto three peaks with temperature maxima at 400, 460 and 580 K. The activation energy and frequencyfactor of these TL glows are found to be in the order of ∼0.58 eV and ∼106 s−1 respectively.
Investigations on yttrium oxide (Y2O3) in its thin film formhas great interest due to their worthy applications and superiorproperties viz., enhanced protective coating in a severely reactiveatmosphere due to its thermal stability, optically transparent overa wide wavelength range (0.28–8 �m), chemical inertness, crys-tallographic phase stability, good mechanical strength, dielectricconstant (k ∼ 18), high refractive index (n ∼ 2), wide optical bandgap (∼5.8 eV) and so on [1–3]. Y2O3 finds application in powderform as well as in the form thin films. It is used as display materialin cathode ray tube at low voltage, plasma panels and field emis-sion displays, also find application as antireflection coatings, opticalwave guides [4–8]. Wide range development of Y2O3 is an essentialfor luminescent displays, since it is one of the best host materialfor optically active rare earth (RE) ions such as Sm3+, Eu3+, Er3+
and others [9,10]. RE materials are comprehensively make use indisplay devices, optical fibres, amplifiers, since they have remark-able luminescent characteristics due to their inner shell electronictransitions between the 4f–4f energy levels [11–15].
Nanostructured materials are having significant electrical,electrochemical, magnetic, mechanical, electrical and optical prop-erties. Y2O3 doped with RE ions is accepted as biomarker. Y2O3phase has polymorphic forms, classified as hexagonal (A), mon-oclinic (B) and cubic (C) [16]. Cubic bixbyite structure of Y2O3coordination number is six and it contains two non-equivalentS6 and C2 symmetry sites [17]. S6 has centrosymmetric charac-ter, where in only magnetic dipole transitions are able to recordboth in absorption and emission of rare earth ions [18]. C2 hasnon centrosymmetric character, here the f–f transitions are par-tially allowed by forced electric dipole due to odd parity terms inthe crystal field. Samarium ions (Sm3+) are having energy levels incomplex structure with ground level 6HJ and 6FJ as well as excitedlevel 4G5/2 [19,20]. The emission of Sm3+ ions are associated withintra 4f shell transition are very competent. So, Sm3+ ions are fre-quently shows a very important task in the luminescent process.Amalgamation of lithium ion (Li) into Y2O3 host material leads tomodification in crystal structure and morphology. It is a successfulway to enhance the luminescence emission properties of phosphor[21,22]. Mechanisms predict that, incorporation Li ion as sensitizeraugments the creation of oxygen vacancies [23,24].
Energy stored by gamma irradiation and thermoluminescence(TL) intensity is due to stimulation (heating) is relative to the radi-ation flux (doses). Measurement of radiation doses using TL is asensitive and powerful tool. A few TL dosimeters (TLD) are available
Thermoluminescence properties of CaO powder obtained from chickeneggshells
K.R. Nagabhushanaa,b,⁎, H.S. Lokeshaa, S. Satyanarayana Reddya, D. Prakasha,c,M. Veerabhadraswamyd, H. Bhagyalakshmid, J.R. Jayaramaiahe
a Physics R &D Centre, PES Institute of Technology, BSK 3rd Stage, Bengaluru 560085, Indiab Department of Physics, PES University, BSK 3rd Stage, Bengaluru 560085, Indiac Department of Physics, Government Science College, Bengaluru 560001, Indiad Green Chemistry Centre, PES Institute of Technology, BSK 3rd Stage, Bengaluru 560085, Indiae Department of Physics, Government First Grade College, Naragunda 582207, India
Eggshell wastage has created serious problem in disposal of the food processing industry which has beentriggered the thoughts of researchers to use wasted eggshells as good source of calcium. In the present work,calcium oxide (CaO) has been synthesized by combustion process in furnace (F–CaO) and microwave oven (M–
CaO) using the source of chicken eggshells. The obtained F–CaO and M–CaO are characterized by XRD, SEMwith EDX and thermoluminescence (TL) technique. XRD pattern of both the samples show cubic phase withcrystallite size 45–52 nm. TL glow curves are recorded for various gamma radiation dose (300–4000 Gy). TwoTL glows, a small peak at 424 K and stronger peak at 597 K are observed. TL response of M–CaO is 2.67 timeshigher than F–CaO sample. TL kinetic parameters are calculated by computerized curve deconvolution analysis(CCDA) and discussed.
1. Introduction
Chicken eggs are favorite food across the world. They are utilized inboth food and non-food for domestic and commercial products. Theconsumption of eggs results in the generation of huge quantity of eggshells as waste product that need to be disposed which causes severeenvironmental problem. To reduce the burden on the environment,serious attempts are being made to find their possible applications invarious fields (Kingori, 2011). Presently, there are few successfulapplications of utilization of eggshells in the field of agriculture inthe form of fertilizers, industrial products viz paints, cosmetics,medicine, building and engineering materials, pharmaceuticals asnutrition (Lee et al., 2013; Yu-Hong and Yu-Jie, 2009; Gowsikaet al., 2014). These amounts to consumption of a small fraction ofwaste eggshells giving rise to scout new avenues to effectively,efficiently and economically utilize eggshells. In this venture, it isworthwhile to examine the eggshells as a source of thermolumines-cence (TL) materials.
The chemical composition of eggshell contains calcium carbonate(94%), magnesium carbonate (1%), calcium phosphate (1%) andorganic matter (4%) (Rivera et al., 1999). Chicken eggshells are used
in heterogeneous catalyst and it shows excellent catalytic activity inbiodiesel production (Buasri et al., 2013; Olutoye et al., 2011). TheChicken eggshells are made up of calcium carbonate (CaCO3) and CaOis obtained when CaCO3 product is heat treated beyond the 700 °C dueto evaporation of gaseous CO2 (Wei et al., 2009). The alkaline earthoxides such as MgO, CaO, and SrO are cubic structured materials. Thedisplacement of an O2- ion in these materials allows the possibility oftwo stable electron centers. The F-center in alkaline earth oxidesconsists of two electrons trapped at the anion vacancy (Pogatshnik,1994). The absorption band appeared at 400 nm is corresponds to F-center.
TL is one of most sensitive method for estimating the concentrationof defects from ionizing radiation. TL generally exhibit glow curve withone or more peaks when the charge carriers are released. Boas et al.,reported the correlation of electron paramagnetic resonance and TL incrystals of highly colored CaO:Mg involvement of a center containinghydrogen ions. TL glow peaks at 65, 180 and 370 K are reported (Boasand Pilbrow, 1985). Jin et al. (2013a) reported TL studies of UVirradiated CaO at room temperature, TL glow curves were recordedfrom 298 K to 473 K. Two broad TL peaks were appeared at 344 K and405 K. Pure CaO shows PL emission band at 2.0 eV at low temperature
http://dx.doi.org/10.1016/j.radphyschem.2017.03.015Received 10 November 2016; Received in revised form 3 March 2017; Accepted 6 March 2017
⁎ Corresponding author at: Department of Physics, PES University, BSK 3rd Stage, Bengaluru-560085.E-mail addresses: [email protected], [email protected] (K.R. Nagabhushana).
Optical investigation on zinc doped cadmium sulphide nanocrystallinethin films
J.R. Jayaramaiah a, *, R. Shamanth b, V. Jayanth c, K.S. Shamala d
a Department of Physics, Government First Grade College, Nargund 582 207, Indiab Department of ECE, Vijaya Vittala Institute of Technology, Bangalore 560 077, Indiac Department of Mechanical Engineering, Siddaganga Institute of Technology, Tumkur 572 103, Indiad Department of Physics, Mount Carmel College (Autonomous), Bangalore 560 052, India
a r t i c l e i n f o
Article history:Received 8 November 2015Received in revised form27 January 2016Accepted 15 April 2016Available online 26 April 2016
Optical investigation on blue shift behavior of zinc doped cadmium sulphide nano-crystalline thin filmshave been prepared by spray pyrolysis method at 375 ± 10 �C. The crystallinity and phase have beencharacterized by glancing angle X-ray diffraction. The XRD peaks confirm the hexagonal structure ofcadmium sulphide. The crystallites sizes are found its range of 15e20 nm. The surface morphology isanalyzed by using field emission scanning electron microscopy. The morphology of the film is seen asuniform distribution of homogeneous fine solid grains which are compact in nature. Optical absorptionspectrum reveals an absorption peak at 475 nm. Indicating that blue shift due to quantum confinementeffect, as a result the direct energy gap is increased and found its value is 2.91 eV. Raman spectrumreveals the longitudinal optical phonon peaks are at 302 cm�1 and 603 cm�1. The noticeable asymmetryand frequency shift confirm the decrease in particle size. X-ray photoelectron spectroscopy reveals thesurface composition and binding energy of elements and it confirm the presence of zinc. The photo-luminescence spectrum reveals an emission peak at 728 nm is analyzed. Zn doped cadmium sulphidethin film is useful for window material in solar cells and luminescent red phosphor.
Nowadays a line of research is focus towards the nano-science.Nanostructure materials attract for physical, chemical, optical andelectrical properties, which are diverse from their bulk counterparts [1]. Significant and innovative physical and chemical prop-erties are generated at nano-scale thin films due to the quantumconfinement effect [2]. Quantum dot solar cells are promisingsensitizing devices for photovoltaic applications in solar energyconversion [3].
The world is suffering from a serious pollution and futuredeplete of fossil fuels. Solar radiation is considered as one of themost abundant supply of free energy in nature. The solar energy isone of the hopeful solutions for the global energy crisis. Thus, solarcells have been extensively studied in order to increase the effi-ciency, and reduce the cost of converting solar energy into elec-tricity. The thin film solar cells open up an exceptional potential in
cost reduction. Polycrystalline nature of cadmium sulphide (CdS)thin film solar cells are the reason for low cost and high conversionefficiency [4].
Hexagonal wurtzite structure of bulk CdS has a melting point of1600 �C and band gap energy is 2.42 eV at room temperature. Itsrefractive index is 2.52 at wavelength 600 nm. It has three phases insize reduction viz. wurtzite, zinc blend and rock salt. Wurtzite is themost stable phase and also easy to synthesize. Wurtzite phase isseen both in bulk and nano-scale, but not in cubic and rock saltphase. It exhibits size dependent behavior, at size 2.5 nm it hasmelting point ~400 �C. The phase changes fromwurtzite to rock saltcubic phase at a very high pressure [5e13]. CdS nano films exhibitsstructural, electronic, optical, luminescence and photo conductingproperties, which deviate from their bulk [14,15]. The probableapplication prospects are in photo detectors, LASER, LED, phosphor,sensors, address decoders, high density magnetic informationstorage and others [16]. The politenesses of ternary compoundshave been much more attractive for the alteration of the band gapand the lattice parameters. In formation of solar cell a lowdimension window layer material is necessary to avoid high cur-rent loss. High efficiency devices require a thin filmwindow layer to
Role of Li ion on luminescence performance of yttrium oxide thinfilms
J.R. Jayaramaiah a, *, K.R. Nagabhushana b, B.N. Lakshminarasappa c
a Department of Physics, Government First Grade College, Nargund 582 207, Indiab Department of Physics, PES University, BSK 3rd Stage, Bangalore 560 085, Indiac Department of Physics, Bangalore University, Bangalore 560 056, India
a r t i c l e i n f o
Article history:Received 15 March 2015Received in revised form19 April 2015Accepted 22 May 2015Available online 2 June 2015
Lithium ion incorporated yttrium oxide thin films have been deposited by spray pyrolysis. The phase andcrystalline nature of the thin film has been studied by glancing angle X-ray diffraction. Fourier trans-formed infrared spectroscopy reveal the broad and sharp absorption and found with peak 875 cm�1.Solid grains in nature are seen in the image of the thin film procured by the field emission-scanningelectron microscopy. The energy gap of the thin film sample has been found through the UVevis ab-sorption studies and found its value is ~5.37 eV. The photoluminescence emission spectrum wasrecorded under the excitation wavelength of 254 nm. Photoluminescence emission spectrum reveals thepeaks are at 390, 485, 525 and 598e625 nm. Gamma irradiated thin films exhibits thermoluminescentglows with peaks at 460 and 538 K. The thermoluminescence glow curves are analyzed through glowcurve shape method.
Yttrium oxide (Y2O3) is emerged as a luminescent phosphor forexcellent potential applications on account of its inherent physicalproperties viz., thermal stability, crystallographic stability(2325 �C), mechanical strength, dielectric constant (~18), band gap(~5.8 eV), optically transparent over a wide wavelength range(0.28e8 mm), refractive index (n ~2) and so on [1e3].
Y2O3 is carry into take part in powder state as well as thin filmform, its applications are low voltage displays cathode ray tube,plasma display panels and field emission displays, antireflectioncoatings, optical wave guiding in optoelectronics and so on [4e8].The innovation of luminescent displays is one of the prime areas ofresearch, where in Y2O3 procure as an excellent host material foroptically active rare earth ions [9]. Thin films of Y2O3 have beenconstructing as one of the most appropriate applicant for electro-luminescent (EL) devices due to its high dielectric constant andgood thermal stabilities [10].
Y2O3 has polymorphic forms, viz., hexagonal (A), monoclinic (B)and cubic (C). It has a coordination number equal to six and formed
with a cubic bixbyite structure. It has two non-equivalent yttriumS6 and C2 symmetry sites. The centrosymmetric character in S6,only magnetic dipole transitions in absorption and emission forrare-earth ions. The non-centrosymmetric character in C2 group,the fef transitions is partially allowed by forced electric dipole dueto odd parity terms in the crystal field [11e13].
The optimized chemical composition, crystallinity and surfacemorphology are the necessary requirements for more efficientluminescent materials. Crystallinity of the thin film is improve bymodifying the composition of precursors, through in which theincorporation of Zn2þ or Liþ ion into the host material. And, bettercrystallinity is one of the successful ways to enhance its lumines-cence performance [14,15]. Several mechanisms are predictable forLiþ ion incorporate as sensitizer effect [15], creation of oxygen va-cancy [16], the role of Liþ ion is mainly endorsed to the sensitizereffect and the creation of oxygen vacancy [14,17].
Many techniques have been employed for the deposition of theoxide thin films. The techniques mainly includes like, chemicalvapor deposition (CVD), electrochemical vapor deposition (EVD),metal-organic chemical vapor deposition (MOCVD), sputtering,laser ablation, electron beam deposition, vacuum evaporation,spray pyrolysis etc. are employed for the growth of thin films[18e22]. Each of the vacuum deposition techniques suffers fromrelatively high equipment cost and complexity. ‘Spray pyrolysis’ is a
Luminescence performance of europium-doped yttrium oxidethin films
J.R. Jayaramaiah a,b, B.N. Lakshminarasappa a,n, K.R. Nagabhushana c
a Department of Physics, Bangalore University, Bangalore 560056, Indiab Department of Physics, Government First Grade College, Nargund 582207, Indiac Department of Physics, PES University, BSK 3rd stage, Bangalore 560085, India
a r t i c l e i n f o
Article history:Received 23 February 2014Received in revised form20 June 2014Accepted 1 August 2014Available online 9 August 2014
Europium-doped yttrium oxide thin films have been deposited by a spray pyrolysis method. Thecrystallite sizes are calculated to be �50 nm using Scherrer's formula. Fourier transformed infraredspectroscopy (FTIR) reveals broad absorption with peak at 875 cm�1. Surface morphology and elementalcomposition of the thin films are studied by a field-emission scanning electron microscope (FESEM)equipped with energy dispersive X-ray spectroscopy (EDS). The energy gap (Eg) of the thin film sample isfound to be �5.37 eV. The film exhibits photoluminescence (PL) emission over 525–550 nm, 585–601 nm, 612 nm and 620–632 nm under the excitation of 240 nm. Gamma (γ)-irradiated films exhibittwo well-resolved thermoluminescent (TL) glows with peaks at 460 and 570 K. The TL glow curves areanalyzed by a glow curve shape method. The activation energy and the frequency factor are found to be,respectively, �0.6 eV, �3�106 s�1 for 460 K and �0.53 eV, �46.72�103 s�1 for 570 K.
& 2014 Elsevier B.V. All rights reserved.
1. Introduction
Yttrium oxide (Y2O3) finds potential application, as a goodprotective coating material in a severely reactive environmentbecause of its thermal stability, optical transparency over a widewavelength range (0.28–8 μm), crystallographic stability up to2325 1C, high mechanical strength, high dielectric constant(k�18), high refractive index (n�2), high band gap (�5.8 eV) andso on [1–3]. Europium-doped yttrium oxide (Y2O3:Eu3þ) has beenprojected as a replacement of SiO2 for dielectric films in electronicdevices because of its high dielectric strength and low leakagecurrent [4]. To develop luminescent properties, extensive researchhas been carried out on rare earth activated oxide phosphors due totheir superiority in color purity as well as chemical and thermalstabilities [5,6]. Y2O3:Eu3þ is still considered as the best red oxidephosphor under the excitation wavelength of 254 nm with itstolerable atmospheric stability, reducing degradation under appliedvoltages and the lack of hazardous constituents unlike sulfidephosphors [5,7]. Y2O3:Eu3þ exhibits red emission, thus it is usedas a red phosphor in three bands fluorescent lamps [8].Y2O3:Eu3þ
has attracted immense attention for use as red phosphors influorescent lamps, high-resolution projection TVs, safety devices
and low-voltage displays, namely cathode ray tubes, plasma displaypanels and field emission displays [9,10]. Y2O3:Eu3þ also findsapplication in scintillating devices [11,12].
Thermoluminescence (TL) is a powerful technique for theestimation of radiation doses. The energy absorbed during irradia-tion and the TL intensity on stimulation (heating) are proportionalto the radiation flux (doses). A number of commercially accessiblethermoluminescent dosimeters (TLD) are available for this pur-pose [13,14]. Y2O3:Eu3þ is a superior material for display and lampapplications. And, such materials may be investigated for theirprobable application in TL dosimeters or scintillating detectors[15–17].
Spray pyrolysis is a conventional method for the deposition ofthin films. It is a simple, low cost and creative technique fordepositing oxide films over large area. Oxide thin films have beendeposited by spraying and thermally decomposing solutions of thecorresponding metal nitrates [18]. In spray pyrolysis, the filmformation takes place by the condensation of atoms or moleculesonto a heated substrate. Thus, the substrate temperature, carriergas flow and solution flow rate play a significant role in formingthe structure of the films ranging from amorphous to crystallinephase. Usually, slow reaction at lower temperatures (o250 1C)would yield foggy films due to insufficient thermal energy for thespreading of the droplets. At higher temperature (250–500 1C),evaporation and precipitate sublimation occurs in successionand the vapors diffuse toward the substrate, where they react
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Journal of Luminescence
http://dx.doi.org/10.1016/j.jlumin.2014.08.0030022-2313/& 2014 Elsevier B.V. All rights reserved.
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a Department of Physics, Bangalore University, Bangalore 560 056, Indiab Department of Physics, Government First Grade College, Nargund 582 207, Indiac Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, India
a r t i c l e i n f o
Article history:Received 10 March 2012Received in revised form 11 June 2012Accepted 30 June 2012Available online 21 July 2012
Keywords:OxideOptical materialScanning electron microscopyThermoluminescence
a b s t r a c t
Luminescence exhibiting europium doped yttrium oxide (Y2O3:Eu3+) phosphor was prepared by solutioncombustion method, using disodium ethylene diamine tetra acetic acid (EDTA-Na2) as fuel at ∼350 ◦C.Powder X-ray diffraction (PXRD) pattern of Y2O3:Eu3+ revealed the cubic crystalline phase. The mor-phology of the samples was studied by scanning electron microscopy (SEM) and was foamy, fluffy andporous in nature. Fourier transformed infrared spectroscopy (FTIR) revealed prominent absorption withpeaks at 3415, 1435, 875 and 565 cm−1. Optical absorption studies showed the energy gap of the syn-thesized samples to be 5.4–5.5 eV. The photoluminescence (PL) of Y2O3:Eu3+ exhibiting emission peakat 611 nm under the excitation of 254 nm. Thermoluminescence of �-irradiated Y2O3:Eu3+ showed twowell resolved TL glows with peaks at 460 and 610 K and they were analyzed by glow curve shape methodand the activation energies were found to be 0.421 eV and 1.016 eV respectively.
Nanoparticles have gained an immense interest, in anticipa-tion that this unexplored range of material dimensions will yieldsize-dependent properties. The physical and chemical proper-ties vary drastically with size, which clearly represents a fertilefield for materials research [1–3]. Producing nano scale mate-rials opens new opportunities in the creation of product withenhanced properties for applications such as electronics, optics,medicine and magnetism. Luminescent phosphors are among thecurrent nanostructures of materials that can be incorporated intovarious applications, viz., the development of flat-panel displaysdepends critically on the design of bright and stable phosphors [4].Nanocrystalline phosphors are suitable for high definition televi-sion (HDTV) where conventional bulk phosphor cannot be used[5].
The morphology and the particle size affect the emission inten-sity of phosphor [6–8]. In general, the luminous efficiency ofphosphor reduces with decreasing particle size as long as the quan-tum size effect does not occur [9]. Y2O3:Eu3+ nanopowder wassynthesized by solution combustion technique in which EDTA-Na2was used as the chelating-fuel. This EDTA has several remarkableadvantages in comparison with other fuels. Because of the greaterability of EDTA anions to chelate metal cations and form very sta-ble and soluble complexes, all of the starting materials are mixed
at the molecular or atomic level in a solution, it is easy to controlthe composition and a high degree of homogeneity is achievable.Solution combustion is a wet-chemical method; it is an exother-mic reaction and occurs with the evolution of heat and light. Sucha high temperature leads to growth of nanocrystalline materials.In any solution combustion fuel and oxidizer are required. Whenthe mixture of fuel and oxidizer is ignited, combustion takes place.For the synthesis of oxides, metal nitrates are used as oxidizer andhydrazine based compounds are employed as fuels [10,11].
Optically transparent yttrium oxide (Y2O3) appears to be a per-spective laser material, because its thermal conductivity is twoand ten times higher than thermal conductivity of YAG and glassrespectively [12]. Nanophosphor Y2O3 crystallites have high lumi-nescence efficiency in the orange-red, high purity, good chemicalresistance and thermal stability. Therefore the Y2O3:Eu3+ powderis largely used in optical display technology, medical image andillumination [13].
In recent years, pure or doped Y2O3 has attracted much attentiondue to its potential application in optoelectronics. This is mainlydue to the qualities of this material such as its high refractiveindex (>1.9), large band gap (5.8 eV), physical and chemical stabil-ity. Refractive index and band gap are crucial parameters in opticalwave guide device. The higher the value of refractive index, themore confined the optical transmission in the guide, thus leading tomore efficient pumping and amplification. Therefore, the investiga-tion of the effects of refractive index and band gap is very important[14].
Y2O3:Eu3+ phosphor exhibits red emissions and has excellentchemical stability. This phosphor is the only existing red phosphorused in three band-fluorescent lamps [15]. Y2O3:Eu3+ has attracted
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Thermoluminescence of combustion synthesized yttrium oxide
B.N. Lakshminarasappa a,⁎, J.R. Jayaramaiah a,b, B.M. Nagabhushana c
a Department of Physics, Bangalore University, Bangalore-560 056, Indiab Department of Physics, Government First Grade College, Hangal-581 104, Indiac Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore-560 054, India
a b s t r a c ta r t i c l e i n f o
Article history:Received 14 April 2011Received in revised form 18 September 2011Accepted 22 September 2011Available online 1 October 2011
Keywords:NanoparticlesCombustion synthesisScanning electron microscopyOxidesThermoluminescence
Pure yttrium oxide (Y2O3) was prepared by solution combustion technique using disodium ethylene diaminetetra acetic acid (EDTA-Na2) as fuel at ~350 °C. Powder X-ray diffraction (PXRD) pattern of Y2O3 revealedcubic crystalline structure with crystallite size in the range of 18–23 nm. The scanning electron microscopy(SEM) indicated the foamy and fluffy nature of the sample. Fourier transformed infrared spectroscopy(FTIR) revealed four prominent absorption with peaks at 3395, 1433, 875 and 566 cm−1. From the opticalabsorption studies the energy gap of the synthesized sample was found to be 5.72 eV. Two well resolvedthermoluminescence (TL) glows with peaks at 475 and 626 K were observed in γ-irradiated Y2O3. The glowcurves were analyzed and the average activation energy was found to be 0.505 and 0.977 eV respectively.
Different techniques are applied to prepare nanocrystals. Theyinclude solid state reaction [1], wet chemical methods such as chemicalvapor deposition [2], combustion [3,4], sol–gel [5], aerosol pyrolysis [6]etc. The solid state reaction method has several shortcomings such asprolonged reaction time, larger size grain growth and poor homogene-ity. However, the salient features of wet chemical methods are that thestarting materials can bemixed at molecular level and the temperatureof formation of the final products is as low as that of conventional solid-state reactions techniques. Among wet chemical methods, ‘solutioncombustion synthesis’ has several advantages. It requires simple ap-paratus and the materials used are more economical [7,8]. It requireslow energy, short time and this technique may also be employed toproduce homogeneous, high-purity, crystalline oxides. The natureof crystallinity, surface area and agglomeration of the synthesizedproducts are primarily governed by flame temperature during combus-tion which itself dependents on the nature of the fuel and the fuel-to-oxidizer ratio [9]. It is known that, a good fuel should react non-violently without producing toxic gasses and act as a complexingagent formetal ions [10]. EDTA-Na2 is one such compoundwhich servesas a fuel during the combustion reaction and gets oxidized by nitrateions and this is used as a new technology for material synthesis [11].This EDTA has several remarkable advantages in comparison withother fuels and it has the greater ability to chelate metal cations andforming very stable and soluble complexes. In this technique, the
startingmaterials aremixed at themolecular or the atomic level in a so-lution and it is easy to control the composition and a high degree of ho-mogeneity is obtained. It is an exothermic reaction and occurs withthe evolution of heat and light. When the mixture of fuel and oxidiz-er is ignited, combustion takes place at high temperature and leads togrowth of materials with nano crystalline form. Metal nitrates andhydrazine based compounds are used as oxidizer and fuels respectivelyto synthesize metal oxides [12].
Oxide phosphors are found to be suitable for field emission display(FED), vacuum fluorescent display (VFD), plasma panel display (PDP)and electroluminescence (EL) devices. Luminescence efficiency isfound to increase as the size of the phosphor particle is decreasedand the preparation of phosphor powders becomes very importantin technological application [13]. When thermoluminescent materialis exposed to γ-radiation, it absorbs and stores energy in the formof defects. A part of the stored energy is released in the form of visiblelight when the two types of defect centers are recombined uponwarming the material.
Metal oxide matrix is proved to be an excellent host material forlasing action. The Y2O3 possesses high refractory properties, a highmelting point (~2450 °C) and a high thermal conductivity (33Wm−1 K−1). It is a suitable material for photonic waveguide due toits high band gap (5.72 eV), with a very high refractive index (~2) anda wide transmission range (280–8000 nm) [14]. Numerous techniquesare applied on the synthesis of rare earth doped nanocrystalline Y2O3
[15–18].In the present work, Y2O3 nanopowder was synthesized by solution
combustion technique in which EDTA-Na2 was used as the chelating-fuel. Further, the TL behavior of the γ-irradiated Y2O3 has been studiedand the enhancement in TL intensity with γ-ray dose was found. In
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Powder Technology
j ourna l homepage: www.e lsev ie r .com/ locate /powtec
This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution
and sharing with colleagues.
Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party
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In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information
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a Department of Physics, Bangalore University, Bangalore 560 056, Indiab Department of Physics, Government First Grade College, Hangal 581 104, Indiac Department of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore 560 054, India
a r t i c l e i n f o
Article history:Received 19 February 2011Received in revised form 4 June 2011Accepted 16 June 2011
Thermoluminescence (TL) of neodymium doped yttrium oxide (Y2O3:Nd3+) nanocrystalline phosphors,synthesized by solution combustion route, using disodium ethylene diamine tetra acetic acid (EDTA-Na2)as fuel, was studied at low temperature (<350 ◦C). Powder X-ray diffraction (PXRD) pattern of Y2O3:Nd3+
revealed the cubic crystalline phase and the average crystallites sizes were found to be in the range of18–24 nm. The morphology of the samples was studied by scanning electron microscopy (SEM) and wasfoamy and fluffy in nature. Fourier transformed infrared spectroscopy (FTIR) revealed prominent absorp-tion with peaks at 3400, 1435, 875 and 565 cm−1. Optical absorption studies showed that the energy gapof the synthesized sample was found to be 5 eV. Thermoluminescence of �-irradiated Y2O3:Nd3+ showedtwo well resolved TL glows with peaks at 587 and 628 K and they were analyzed by glow curve shapemethod and the activation energies were found to be 1.83 eV and 2.2 eV respectively.
Nanoparticles have become a research focus in terms of boththeir fundamental and technological importance, especially in thecase of luminescent materials because of a quantum confinementeffect, which leads to novel optoelectronic properties. It was foundthat the emission lifetime and luminescence quantum efficiencydepends strongly on the nanosize [1–4].
‘Solution combustion’ is yet another wet-chemical method,which does not require further calcinations and repeated heating.It is an exothermic reaction and occurs with the evolution of heatand light. Such a high temperature leads to growth of nanocrys-talline material. In any solution combustion, fuel and oxidizer arerequired and when this mixture is ignited, combustion takes place.For the synthesis of oxides, metal nitrates are used as oxidizer andhydrazine based compounds are employed as fuels [5,6].
Rare earth sesquioxides (RE2O3) have been of great scientificand technological interest for many years because of their attractivephysical and chemical properties. Actually, they are excellent hostmaterials for lasers, with high thermal stability [7–9].
Yttrium oxide (Y2O3) for example is an interesting host mate-rial for high power laser applications with a very high melting pointof ∼2430 ◦C, a cubic structure of the space group Ia3 and a latticeconstant of 10.6041 A [10,11]. Moreover, Y2O3:Nd3+ sesquioxideis a good phosphor used as light emitting devices and its lumi-nescent properties were studied [12]. The principal roles for NIRlight emission in heavily doped Nd3+ ions in oxide glasses playphonon-relaxation mechanisms [13]. Numerous studies have beencarried out on the synthesis and properties of rare earth dopedY2O3 [14–17]. In the present work, we report the TL propertiesof �-irradiated nanocrystalline Y2O3:Nd3+, synthesized by self-propagating low-temperature solution combustion process usingEDTA-Na2 as a fuel.
2. Experimental
Nanophosphor Y2O3:Nd3+ (Y1.99Nd0.01O3) was prepared by solution combustionsynthesis. Yttrium oxide (99.99%, Sd. Fine Chem), neodymium oxide (99.99%), nitricacid and EDTA-Na2 were used as starting raw materials to prepare Y2O3:Nd3+. Sto-ichiometric amounts of Y2O3 and Nd2O3 were converted into nitrate by dissolvingin 1:1 nitric acid and excess nitric acid was removed by evaporation on a sand bath.The stoichiometric amount of EDTA-Na2 was dissolved in double distilled water,the solution was poured in to the crystalline dish containing yttrium nitrate dopedwith Nd, and the stoichiometric solution was stirred well to ensure homogene-ity. The dish with solution was placed in a muffle furnace whose temperature wasmaintained at <350 ◦C. The reaction mixture underwent thermal dehydration andignited at one spot with liberation of gaseous products such as oxides of nitrogen and
aDepartment of Physics, Bangalore University, Bangalore-560 056
bDepartment of Physics, Government First Grade College, Hangal-581 104 cDepartment of Chemistry, M.S. Ramaiah Institute of Technology, Bangalore-560 054
1. Introduction Nanoparticles have an immense interest in anticipation that this unexplored range of material dimensions will yield size-dependent properties. The physical and chemical properties vary drastically with size, which clearly represents a fertile field for materials research [1-3]. Among the various nanomaterials, luminescent nanoparticles have attracted increasing technological and industrial interest because of their optical and luminescence properties [4, 5]. Solution combustion is a wet-chemical method which does not require further calcinations and repeated heating. It is an exothermic reaction and occurs with the evolution of heat and light. Such a high temperature leads to growth of nanocrystalline materials. In any solution combustion fuel and oxidizer are required. When the mixture of fuel and oxidizer are ignited, combustion takes place. For the synthesis of oxides, metal nitrates are used as oxidizer and hydrazine based compounds are employed as fuels [6, 7]. Yttrium oxide has attracted much attention because of several physical properties (high k:10-18), wide band gap (~5.5 eV), high refractory properties with melting point (~2450 0C), high thermal conductivity ( ~33 Wm-1K-1), high refractive index (~2), wide transmission range (280-8000 nm) [8]. Rare earth doped solid state materials have become an important class of solids attracting much attention among researches, as is evidenced by the literature survey. The electronic energy of the 4f compounds (RE ions) have become a subject of enduring interest as they are useful as a spectral probe to study the perturbation effects in a host lattice and they are not much affected by the crystal field due to there inner 4fn shell [9]. The spectroscopic investigations of the energy levels of Sm3+ ions doped in different hosts have been reported [10, 11]. In this work we report on self propagating low-temperature (<350oC) Solution combustion synthesis of Y2O3:Sm3+ nanoparticles using EDTA-Na2 as fuel and to estimate the band gap energy and also the TL properties. 2. Experimental Nanophosphor Y2O3:Sm3+ was prepared by ‘solution combustion synthesis’. Yttrium oxide (99.99%, sd.fine-chem), samarium oxide, nitric acid and EDTA-Na2 were used as starting raw materials to prepare Y2O3:Sm3+. The samples were characterized by the powder X-ray diffraction. The morphology was studied by scanning electron microscopy. The Fourier-transformed infrared absorption spectra were recorded using Nicollet Magna 550 spectrometer with KBr pellets in the range of 400 - 4000 cm-1. The energy gap was calculated using ELICO (SL -159) UV-VIS spectrophotometer. The TL glow curves of Y2O3:Sm3+ were recorded with an home made TL set up consisting of a small metallic heating strip, temperature programmer, photomultiplier tube (931B) and a multimeter recorder (Rishicom) at a heating rate of 5oCs-1. Then the TL glow curves obtained above were deconvoluted using Origin software. 3. Results and discussion The samples of Y2O3:Sm3+ were prepared by solution combustion technique. Stoichiometric amounts of Y2O3 and Sm2O3 were converted into nitrate by dissolving in 1:1 nitric acid and excess nitric acid was removed by evaporation on a sand bath. The Stoichiometric amount of EDTA-Na2 was dissolved in double distilled water, the solution was poured in to the crystalline dish and the solution was placed in a muffle furnace. The temperature was maintained at<350oC. The reaction mixture underwent thermal dehydration and ignited at one spot with liberation of gaseous products such as oxides of nitrogen and carbon. The combustion propagated throughout the reaction mixture without further need of any external heating, as the heat of reaction is sufficient for the _______________________________________________________________________________ *Corresponding author: E-mail: [email protected]
ISSN 2277 – 6362 International Journal of Luminescence and Applications Vol.1 (I)
