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Previous issue date: 2017-08-31 === Os materiais que pertencem a fam?lia dos molibdatos com estrutura cristalina tipo scheelita t?m sido objeto de pesquisas ao longo do tempo. O amplo interesse nestes compostos reside em suas excelentes propriedades ?pticas, que formam a base de sua utiliza??o como subst?ncias fosforescentes, materiais para lasers, e detectores de cintila??o entre outros. A t?cnica de spray pir?lise ultrass?nica, por sua vez, ? uma t?cnica de produ??o cont?nua de p?s, de apenas uma etapa, de f?cil controle dos par?metros e apesar de ser uma metodologia amplamente utilizada, n?o h? refer?ncias de seu uso para a produ??o de molibdatos de c?lcio puro e com dopagem de terras raras. Neste trabalho foi estudado a obten??o de part?culas de molibdato de c?lcio (CaMoO4) puro, dopado com diferentes porcentagens em mol de 1%, 2% e 4% das terras raras Eu+3, Tb+3, Tm+3, e a mistura das tr?s terras raras (TR) a partir da t?cnica de spray pir?lise ultrass?nico (SPU). O tempo de perman?ncia dentro do reator de fluxo laminar, foi de 27 segundos Os materiais obtidos foram caracterizados pelas t?cnicas de difra??o de raios-X, espectroscopia de micro Raman, espectroscopia ?tica nas regi?es do ultravioleta-vis?vel, microscopia eletr?nica de varredura com canh?o de el?trons por emiss?o de campo e espectroscopia de fotoluminesc?ncia e coordenadas de cor do CaMoO4 com TR. Os resultados indicaram que a t?cnica de spray pir?lise ultrass?nico produziu material de alta pureza, nas dimens?es nano e micro, com morfologia esf?rica. Com a adi??o das terras raras com diferentes porcentagens em mol de 1%, 2% e 4% e sua TR na estrutura do CaMoO4, foi poss?vel observar as emiss?es de fotoluminesc?ncia caracter?sticas das terras raras e a obten??o de materiais com emiss?es no branco para as amostras de CaMoO4 com 2% e 4% da TR. === The materials belonging to the molybdates family with crystalline structure type scheelite have been object of research over time. The wide interest in these compounds lies in their excellent optical properties, which form the basis of their use as phosphors, materials for lasers, and scintillation detectors among others. The ultrasonic pyrolysis spray technique is a technique of continuous production of single-step powders, easy to control parameters and although it is a widely used methodology, there are no references of its use for the production of calcium molybdates and with rare earth doping. In this study, the preparation of pure calcium molybdate (CaMoO4) particles with different mole percentages of 1%, 2% and 4% of the rare earths Eu+3, Tb+ 3 , Tm+ 3, and their respective mixtures (TR) were studied from the ultrasonic pyrolysis spray technique. The residence time inside the laminar flow reactor was 27 seconds. The materials obtained were characterized by X-ray diffraction techniques, micro Raman spectroscopy, ultraviolet-visible optical spectroscopy, scanning electron microscopy with field emission electron gun and photoluminescence spectroscopy. The results shown that the ultrasonic pyrolysis spray technique produced high purity material in the nano and micro dimensions with spherical morphology. With the addition of rare earths with different percentages of 1%, 2% and 4% mol and their mixture in the structure of CaMoO4, it was possible to observe the photoluminescence emissions characteristic of rare earths and to obtain materials with white emissions for the samples of CaMoO4 with 2% and 4% TR.
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