15 research outputs found

    Rapid synthesis and enhancement in down conversion emission properties of BaAl2O4:Eu2+,RE3+ (RE3+=Y, Pr) nanophosphors

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    [EN] BaAl2O4:Eu2+,RE3+ (RE3+=Y, Pr) down conversion nanophosphors were prepared at 600 °C by a rapid gel combustion technique in presence of air using boron as flux and urea as a fuel. A comparative study of the prepared materials was carried out with and without the addition of boric acid. The boric acid was playing the important role of flux and reducer simultaneously. The peaks available in the XPS spectra of BaAl2O4:Eu2+ at 1126.5 and 1154.8 eV was ascribed to Eu2+(3d5/2) and Eu2+(3d3/2) respectively which confirmed the presence of Eu2+ ion in the prepared lattice. Morphology of phosphors was characterized by tunneling electron microscopy. XRD patterns revealed a dominant phase characteristics of hexagonal BaAl2O4 compound and the presence of dopants having unrecognizable effects on basic crystal structure of BaAl2O4. The addition of boric acid showed a remarkable change in luminescence properties and crystal size of nanophosphors. The emission spectra of phosphors had a broad band with maximum at 490–495 nm due to electron transition from 4f65d1 → 4f7 of Eu2+ ion. The codoping of the rare earth (RE3+=Y, Pr) ions help in the enhancement of their luminescent properties. The prepared phosphors had brilliant optoelectronic properties that can be properly used for solid state display device applications.The authors gratefully recognize the financial support from the University Grant Commission (UGC), New Delhi [MRP-40-73/2011(SR)] and the European Commission through Nano CIS project (FP7-PEOPLE-2010-IRSES ref. 269279).Singh, D.; Tanwar, V.; Simantilke, AP.; MarĂ­, B.; Kadyan, PS.; Singh, I. (2016). Rapid synthesis and enhancement in down conversion emission properties of BaAl2O4:Eu2+,RE3+ (RE3+=Y, Pr) nanophosphors. Journal of Materials Science: Materials in Electronics. 27(3):2260-2266. https://doi.org/10.1007/s10854-015-4020-1S22602266273J.S. Kim, P.E. Jeon, J.C. Choi, H.L. Park, S.I. Mho, G.C. Kim, Appl Phys Lett 84, 2931 (2004)D. Jia, D.N. Hunter, J Appl Phys 100, 1131251 (2006)H. Aizawa, T. Katsumata, J. Takahashi, K. Matsunaga, S. Komuro, T. Morikawa, E. Toba, Rev Sci Instrum 74, 1344 (2003)C.N. Xu, X.G. Zheng, M. Akiyama, K. Nonaka, T. Watanabe, Appl Phys Lett 76, 179 (2000)C. Feldmann, T. Justel, C.R. Ronda, P.J. Schmidt, Adv Funct Mater 13, 511 (2004)P.J. Saines, M.M. Elcombe, B.J. Kennedy, J Solid State Chem 179, 613 (2006)R. Sakai, T. Katsumata, S. Komuro, T. Morikawa, J Lumin 85, 149 (1999)T. Aitasalo, P. Deren, J Solid State Chem 171, 114 (2003)S. Nakamura, T. Mukai, M. Senoh, J Appl Phys 76, 8189 (1994)S.H.M. Poort, G. Blasse, J Lumin 72, 247 (1997)P. Mingying, H. Guangyan, J Lumin 127, 735 (2007)X. Linjiu, H. Mingrui, T. Yanwen, C. Yongjie, K. Tomoaki, Z. Liqing, W. Ning, Jap J Applied Physics 46, 5871 (2007)T. Aitasalo, J. HölsĂ€, H. Jungner, M. Lastusaari, J. Niittykoski, J Phys Chem B 110, 4589 (2006)R. Stefani, L.C.V. Rodrigues, C.A.A. Carvalho, M.C.F.C. Felinto, H.F. Brito, M. Lastusaari, J. HölsĂ€, Opt Mater 31, 1815 (2009)M. Peng, G. Hong, J Lumin 127, 735 (2007)V. Singh, V. Natarajan, J.J. Zhu, Opt Mater 29, 1447 (2007)X.Y. Chen, C. Ma, X.X. Li, C.W. Shi, X.L. Li, D.R. Lu, J Phys Chem C 113, 2685 (2009)A.J. Zarur, J.Y. Ying, Nature 403, 65 (2000)J. Chen, F. Gu, C. Li, Cry Growth Des 8, 3175 (2008)J. Zhang, M. Yang, H. Jin, X. Wang, X. Zhao, X. Liu, L. Peng, Mater Res Bull 47, 247 (2012)P. Maƛlankiewicz, J. Szade, A. Winiarski, Ph Daniel, Cryst Res Technol 40, 410 (2005)Y.J. Chen, G.M. Qiu, Y.B. Sun et al., J Rare Earths 20, 50 (2002)F.C. Palilla, A.K. Levine, M.R. Tomkus, J Electrochem Soc 115, 642 (1968)J. Niittykoski, T. Aitasalo, J. Holsa, H. Jungner, M. Lastusaari, M. Parkkinen, M. Tukia, J Alloys Compd 374, 108 (2004)A. Nag, T.R.N. Kutty, J Alloys Compd 354, 221 (2003)D. Haranath, P. Sharma, H. Chander, J Phys D Appl Phys 38, 371 (2005

    Pure and multi metal oxide nanoparticles: synthesis, antibacterial and cytotoxic properties

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    The controlled disassembly of mesostructured perovskites as an avenue to fabricating high performance nanohybrid catalysts

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    © The Author(s) 2017. Versatile superstructures composed of nanoparticles have recently been prepared using various disassembly methods. However, little information is known on how the structural disassembly influences the catalytic performance of the materials. Here we show how the disassembly of an ordered porous La0.6Sr0.4MnO3 perovskite array, to give hexapod mesostructured nanoparticles, exposes a new crystal facet which is more active for catalytic methane combustion. On fragmenting three-dimensionally ordered macroporous (3DOM) structures in a controlled manner, via a process that has been likened to retrosynthesis, hexapod-shaped building blocks can be harvested which possess a mesostructured architecture. The hexapod-shaped perovskite catalyst exhibits excellent low temperature methane oxidation activity (T90%=438 °C; reaction rate=4.84 × 10−7 mol m−2 s−1). First principle calculations suggest the fractures, which occur at weak joints within the 3DOM architecture, afford a large area of (001) surface that displays a reduced energy barrier for hydrogen abstraction, thereby facilitating methane oxidation

    Photocatalytic oxidation of methane over silver decorated zinc oxide nanocatalysts

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    The search for active catalysts that efficiently oxidize methane under ambient conditions remains a challenging task for both C1 utilization and atmospheric cleansing. Here, we show that when the particle size of zinc oxide is reduced down to the nanoscale, it exhibits high activity for methane oxidation under simulated sunlight illumination, and nano silver decoration further enhances the photo-activity via the surface plasmon resonance. The high quantum yield of 8% at wavelengths \u3c 400 nm and over 0.1% at wavelengths Âż 470 nm achieved on the silver decorated zinc oxide nanostructures shows great promise for atmospheric methane oxidation. Moreover, the nano-particulate composites can efficiently photo-oxidize other small molecular hydrocarbons such as ethane, propane and ethylene, and in particular, can dehydrogenize methane to generate ethane, ethylene and so on. On the basis of the experimental results, a two-step photocatalytic reaction process is suggested to account for the methane photo-oxidation

    Highly stable, mesoporous mixed lanthanum–cerium oxides with tailored structure and reducibility

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    Pure and mixed lanthanum and cerium oxides were synthesized via a reverse microemulsion-templated route. This approach yields highly homogeneous and phase-stable mixed oxides with high surface areas across the entire range of La:Ce ratios from pure lanthana to pure ceria. Surprisingly, all mixed oxides show the fluorite crystal structure of ceria, even for lanthanum contents as high as 90%. Varying the La:Ce ratio not only allows tailoring of the oxide morphology (lattice parameter, pore structure, particle size, and surface area), but also results in a fine-tuning of the reducibility of the oxide which can be explained by the creation of oxygen vacancies in the ceria lattice upon La addition. Such finely controlled syntheses, which enable the formation of stable, homogeneous mixed oxides across the entire composition range, open the path towards functional tailoring of oxide materials, such as rational catalyst design via fine-tuning of redox activity
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