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Buldhana, India

Ingle J.T.,Jd Institute Of Engineering And Technology | Sonekar R.P.,Arts and Commerce College | Omanwar S.K.,Sant Gadge Baba Amravati University | Wang Y.,Lanzhou University | Zhao L.,Lanzhou University
Journal of Alloys and Compounds | Year: 2014

An efficient and chromatic red emitting borate host phosphors (Y 1-x-y,Gd x)BaB9O16:Eu3+y were prepared by a simple route of solution combustion technique for different composition of host (0 ≤ x ≤ 0.97, y = 0.03). The synthesis is based up on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate). The heat generated in reaction is utilized for auto combustion of ingredients. Crystal structure and phase formation of product was identified by powder XRD technique while particle morphology was studied by FE-SEM. The photoluminescence (PL) properties under 252 nm ultraviolet (UV) and 147 nm vacuum ultraviolet (VUV) excitation were investigated. It was found that for increasing concentration of Gd dominant emission shift towards longer wavelength and more chromatic side while for optimal doping concentration of Gd 3+ ions an intermediate role for energy transfer mechanism from sensitizer to activator is highly efficient which increase transition probability of electric dipole of 5D0 → 7F2 of Eu3+ ion to emits pure and intense red line at 615 nm. This phosphor could be potential candidate for plasma display panel (PDPs) and mercury free lamps. © 2014 Elsevier B.V. All rights reserved. Source


Nagpure P.A.,Sant Gadge Baba Amravati University | Bajaj N.S.,Sant Gadge Baba Amravati University | Sonekar R.P.,Arts and Commerce College | Omanwar S.K.,Sant Gadge Baba Amravati University
Indian Journal of Pure and Applied Physics | Year: 2011

The lanthanum pentaborate (LaB5O9)is a novel material which exhibits excellent luminescence when doped with rare earth ions. Itwas prepared by a novel technique which is a slight variation of solution combustion synthesis. The synthesis is based on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate). The structure of the prepared material was confirmed by powder XRD technique. The photoluminescence of rare earth ions (Ce3+, Eu3+) and sensitized luminescence of Gd 3+(Pr3+-Gd3+ and Bi3+-Gd 3+) in LaB5O9 have been studied. LaB 5O9:Ce3+ shows broad band UV emission at 317 nm and LaB5O9:Eu3+ shows orange red emission. LaB5O9: Pr3+-Gd3+ and LaB 5O9: Bi3+-Gd3+ exhibit efficient luminescence of Gd3+ in narrow UVB region at 310 nm. The material (La0.5 Pr0.4)B5O9:Gd0.1 exhibits intense narrow band UVB emission at 310 nm and could be a potential candidate for UVB phosphors used in phototherapy lamps. Source


Chandak H.S.,Arts and Commerce College | Zade S.S.,Indian Institute of Science
Organic Electronics: physics, materials, applications | Year: 2014

Density functional theory calculations were carried out on fused oligothiophenes, their cation radicals and dications (singlet and triplet spin multiplicity) as well as fused polythiophene at B3LYP/6-31G(d) level of theory and compared with their selenophene analogues. The effective conjugation in both the series of fused oligomers was compared on the basis of 'bond length alternation' (BLA). Fused oligo- and polyselenophenes have a more quinoidal character and lower band gap (HOMO-LUMO gap) than their thiophene analogues. The band gaps of polymers were obtained by extrapolation of HOMO-LUMO gap versus 1/n. The deviation from 1/n dependence in HOMO-LUMO gaps starts from n ≥ 31. Thus HOMO-LUMO gaps show convergence behavior. Similar to that of the linear non-fused oligomers of thiophene and selenophene, fused oligothiophene and -selenophene show linear relationship between the internal reorganization energy for self-exchange hole-transfer process (λ) and the square root of chain length only for short oligomers. For longer oligomers, it follows a linear relationship with the reciprocal of chain length and extrapolation gives λ ≈ 0 for polymers. The dications longer than 11-mer showed the RHF/UHF instability and it can be understood as the contribution of the polaron-pair state to the ground-state structure. The calculations suggest that triplet is never a ground state for fused oligothiophene and -selenophene dications. The polaron-pair contribution to the ground state of dication increases with chain length of fused oligothiophene and -selenophene. The triplet state and unrestricted singlet state become degenerate for longer fused oligothiophene and -selenophene, whereas for smaller fused oligomer (up to 20-mer) the singlet state dications are more stable than triplet state dications. The fused oligo- and polythiophene and -selenophene behave similar to the non-fused linear oligo- and polythiophene and -selenophene and do not behave like oligo- and polyacenes. © 2014 Elsevier B.V. All rights reserved. Source


N-[4-(2,3-dibromo-3-aryl-propanoyl)-phenyl]benzenesulfonamide on reaction with hydroxylamine hydrochlorde in ethanol in presence of catalytic amount of piperidine afforded N-(4-(5-arylisoxazol-3-yl)phenyl)benzenesulfonamides. Under microwave irradiation, reaction proceeds smoothly in ethanol without using piperidine. The reaction time was 4-5 minutes and yields were better. The synthesized compounds are characterized by elemental analysis, IR, 1H NMR and Mass spectral data. Source


Ingle J.T.,J D Institute Of Engineering And Technology | Sonekar R.P.,Arts and Commerce College | Omanwar S.K.,Sant Gadge Baba Amravati University | Wang Y.,Lanzhou University | Zhao L.,Lanzhou University
Combustion Science and Technology | Year: 2014

The inorganic borate host phosphors YBo3:RE ion (RE = Eu 3+,Tb3+) were synthesized by a novel solution combustion technique. The synthesis is based on the exothermic reaction between fuel (urea) and oxidizer (ammonium nitrate). The heat generated in the reaction was used for auto combustion of precursors. The photoluminescence properties and spectroscopic investigation of the phosphor powder samples were investigated under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation. The phosphors YBo3:Eu3+ and YBo3:Tb3+ show strong absorption in the UV and VUV region and exhibit intense orange-red and green emission, respectively, when excited by 254 nm UV and 147 nm VUV radiation. The phosphor YBo3 doped with Eu3+ and Tb3+ could be an efficient VUV-excited phosphor for plasma display phosphors (PDP) applications. © 2014 Copyright Taylor and Francis Group, LLC. Source

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