Luminóforo azul preparado a partir do método de combustão

Abstract

Neste trabalho, o luminóforo azul Sr2CeO4 é preparado a partir de um precursor multicomponente na forma de pó via método de combustão, variando-se o combustível, resultando num pó de partículas finas. A utilização de ácido cítrico ou glicina como combustível leva à formação de composições diferentes, que após tratamento térmico a 950ºC, convertem-se em um material com predominância da fase Sr2CeO4. A emissão de luz branca azulada é somente observada nas amostras após tratamento térmico, e seus espectros de excitação e de emissão são idênticos e característicos da fase luminescente Sr2CeO4. Portanto o método de combustão é apropriado para preparação de luminóforos azuis.

Morphological and luminescent studies on nanosized Er, Yb–Yttrium oxide up-converter prepared from different precursors

“…In the combustion method, doped yttrium oxide was produced based on [14][15][16] by heating rareearth nitrate solutions with glycine. The synthesis reaction could be described by the following equation:…”

“…Basic carbonate and polymeric precursors have already been successfully applied in the preparation of nanosized yttrium oxysulfide upconverter phosphors doped with ytterbium and erbium (green emission) or ytterbium and thulium (blue emission) [13]. Another method that has been used to prepare all kinds of rare-earth oxides is the combustion one [14][15][16]. In this case, different fuels have been used, resulting in nanosized powders that can lead to transparent ceramics [17].…”

“…1, using the Scherrer formula[14], of the yttrium oxide samples doped with 4% Yb 3+ and 0.1% Er 3+ prepared from different precursors as well as the diameter measurements from SEM and TEM images,Figs. 2 and 3…”

Morphological study of Sr2CeO4 blue phosphor with fine particles

“…The precursor solutions were concentrated by heating it in a porcelain crucible until excess free water evaporated and spontaneous ignition occurred, resulting in fine powder product, which was grounded. Based on thermal analysis as well as X-ray diffraction studies just reported 14 , the conditions of thermal treatment of the powdered multi-component precursors from combustion synthesis were established as being 950 o C during 4 h in order to result in Sr 2 CeO 4 as single phase. Sr 2 CeO 4 was also prepared from a stoichiometric mixture of SrCO 3 (Aldrich, grade reagent) and CeO 2 (Aldrich, 99.999%) fired at 1000 o C, 4 h, and from polymeric precursor heated at 1100 o C during 4 h, as described in a previous paper 11 .…”

Luminescent and morphological study of Sr2CeO4 blue phosphor prepared from oxalate precursors

“…The combustion method [17,18] and a polymer sol-gel route [19,20] involving polyetileglycol (PEG-2000) [21] have also been used.…”