EVERTON BONTURIM
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Artigo IPEN-doc 23270 Persistent luminescence of inorganic nanophosphors prepared by wet-chemical synthesis2018 - BONTURIM, EVERTON; MERIZIO, LEONNAM G.; REIS, ROBERTO dos; BRITO, HERMI F.; RODRIGUES, LUCAS C.V.; FELINTO, MARIA C.F.C.The synthesis of efficient nanosized persistent luminescence materials remains a challenge for the community. Paradoxically, due to the dependence of the point lattice defects and the persistent luminescence efficiency, the control of the defect formation, favorable when the materials are prepared at high temperatures, normally leads to particle growth and sintering. In this work, efficient nanosized rare earth doped disilicates Sr2MgSi2O7:Eu2þ,Dy3þ were synthesized via three different wet-chemical methods taking advantages of the microwave-assisted reduction process as a support step to produce high-quality polycrystalline materials. The crystallite size of the sample showed to be smaller when the decomposition temperature of the precursors is higher and close to the phase formation energy. The excitation VUV spectroscopy indicated that despite being nanocrystalline, the materials optical band gap has just a small difference compared one to another. The reduction of Eu3þ to Eu2þ was successfully obtained, since the f-d interconfigurational transitions of Eu2þ 4f65d1/4f7 emission were observed in the blue region of the spectra. The persistent luminescence efficiency measured through its lasting decay time was close to the commercial materials references and with the advantage of having size control during the synthesis method that can lead to the size dependent applications of photonic materials.Artigo IPEN-doc 21301 Oxygen stoichiometry of Basub(0.50)Srsub(0.50)Cosub(0.80)Fesub(0.20)Osub(3-'delta') obtained by EDTA-citrate method and measured by X-ray and neutron diffraction2015 - BONTURIM, EVERTON; MAZZOCCHI, VERA L.; PARENTE, CARLOS B.R.; MESTNIK FILHO, JOSE; LIMA, NELSON B. de; SEO, EMILIA S.M.The compound Ba0.50Sr0.50Co0.80Fe0.20O3–d (BSCF) has been used as a good candidate for air electrodes in Intermediate Temperature Solid Oxide Fuel Cells. Present work deals with the oxygen vacancy of this compound synthesized by using the EDTA–Citrate method. To obtain a single-phase sample, three portions of the compound were calcined at 700, 800 and 900 C. Only the sample calcined at 900 C showed a single phase. The stoichiometry of the single-phase sample, in particular of the oxygen atom, was determined by applying the combined X-ray and neutron Rietveld refinement to X-ray and neutron powder diffraction patterns measured with the sample.Artigo IPEN-doc 20130 Physical and microstructural characterization of cathode composite cathode and electrolyte ceramics to ITSOFC2014 - VARGAS, REINALDO A.; BONTURIM, EVERTON; ANDREOLI, MARCO; CHIBA, RUBENS; SEO, EMILIA S.M.The (La0.60Sr0.40)(Co0.20Fe0.80)O3-δ - LSCF, (Ce0.90Gd0.10)O1.95 - CGO composites and LSCF were deposited by wet powder spraying deposition method for the purpose of investigating their potential use in Intermediate Temperature Solid Oxide Fuel Cells. The interlayers are necessary between CGO electrolytes and LSCF cathodes in order to improve the performance of these materials. LSCF powders synthesized by citrate technique were calcined at 900 °C for 4 h and, their LSCFCGO composites and LSCF suspensions deposited on CGO substrate and, sintered in 1100 °C for 1 h, were formed pseudo-perovskite. The ceramics materials were analyzed by X-ray diffraction (XRD) and chemical composition of different half-cells layers by scanning electron microscope with energy dispersive (SEM-EDS). The results are in agreement with the literature and indicate that route studied is adequate for crystal structures formation compatible with films the 35 µm thick total for study of conductivity between the cathode and the electrolyte.Artigo IPEN-doc 17831 Vazamento na Central Nuclear de Penly2012 - BONTURIM, EVERTONArtigo IPEN-doc 19196 Avaliação das propriedades do Basub(0,50)Srsub(0,50)Cosub(0,80)Fesub(0,20)Osub(3-d) para células a combustível de óxido sólido de temperatura intermediária obtido pelo método citratos-EDTA2013 - BONTURIM, E.; VARGAS, R.A.; ANDREOLI, M.; SEO, E.S.M.Ba0,50Sr0,50Co0,80Fe0,20O3-d (BSCF) apresenta propriedades físicas, químicas e microestruturais adequadas para compor o cátodo de uma célula a combustível de óxido sólido de temperatura intermediária (ITSOFC). Este trabalho tem por objetivo a síntese e a caracterização do BSCF obtido pelo método dos citrados-EDTA. Os resultados obtidos por difração de raios X (DRX) indicaram fases secundárias para o material calcinado a 700 e 800 ºC e fase única com estrutura cristalina do tipo perovskita para 900 ºC. As micrografi as obtidas por microscopia eletrônica de varredura dos particulados evidenciou a formação de aglomerados de tamanho < 20 μm. A análise dilatométrica dos compactos indicou a temperatura de sinterabilidade ~ 1050 ºC. Os resultados de DRX das cerâmicas sinterizadas evidenciaram a presença de fase única perovskita. As micrografi as dos sinterizados confi rmaram a formação de maior porosidade nas amostras sinterizadas a 1000 °C /1 h, conformadas com pó calcinado a 900 °C. Palavras-chave: método dos citratos-EDTA, ITSOFC, cátodo, perovskita.Artigo IPEN-doc 18219 Effect pH variation of powder materials of the composite oxide Ba(x)Sr(1-x)Co(y)Fe(1-y)O3-d obtained by Citrate-EDTA Method2012 - BONTURIM, EVERTON; VARGAS, REINALDO A.; ANDREOLI, MARCO; CHIBA, RUBENS; SEO, EMILIA S.M.Artigo IPEN-doc 18240 Characterization of LSCF-based composite and LSCF as cathodes for intermediate temperature SOFCs2012 - VARGAS, REINALDO A.; BONTURIM, EVERTON; ANDREOLI, MARCO; CHIBA, RUBENS; SEO, EMILIA S.M.