E0014

Structure Refinement of (Sr_1-x,Ba_x)Nb₂O₆ Ceramic Powders. Y. P. Mascarenhas^a J.G. Carrio^b, I.A. Santos^c, D. Garcia^c, and J.A. Eiras^c, ^aInstituto,de Física de São Carlos, Uni. São Paulo, São Carlos, SP- Brasil, ^bUniv. Presbiteriana Mackenzie, São Paulo, Brasil, ^bCentro Univ. Salesiano de São Paulo, Americana, SP-Brasil, ^cUniv. Federal de São Carlos, SP, Brasil.

Ceramic powders of the compounds Sr_1-xBa_xNb₂O₆ were prepared by solid state reaction of oxides mixtures and sintered at the temperature T = 1100 ^oC. Powders with the nominal compositions SBN25/75, SBN50/50, SBN66/34 and SBN75/25 were studied by X rays powder diffraction using conventional K_Cu radiation with a rotatory anode source. The structures were refined by the Rietveld Method using the program GSAS and a quantitative phase analysis was performed when necessary. The Rietveld refinements indicate that the powders with nominal compositions SBN25/75 and SBN66/34 resulted in monophasic compounds, while the nominal compositions SBN50/50 and SBN75/25 resulted in polyphasic mistures of SBN 52/48 and SBN64,5/30,5 with strong presence of the secondary phase SrNb₂O₆ (SN). This required a quantitative phase analysis, which detailed results are presented in this work. Acknowledgments: FAPESP and CNPq (Brasil)

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