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|Type:||Artigo de periódico|
|Title:||Silver antimonates with pyrochlore-like structure prepared by thermal treatment of silver proton-exchanged antimonic acid: Formation process and structural characterization|
|Abstract:||Silver proton-exchanged antimonic acids, with pyrochlore-type structure and composition of H2-xAgxSb2O6. nH(2)O,(0 < x <2) have been obtained, and they have been used as precursors for preparing silver antimonates The ionic conductivity of the silver proton-exchanged samples as prepared is dominated by proton motion, which is clearly affected by the water content. The formation reaction of silver antimonates has been followed by thermal analysis, mass spectrometry, X-ray diffraction, etc. Four regions can be distinguished: (i) from room temperature to 400 degrees C, weakly bonded water and protons are removed as water; (ii) from 400 to. 600. degrees C, oxygen is removed from the pyrochlore framework leading to reduction of some Sb5+ to Sb3+; (III) from 600 to 950 degrees C, thermally stable silver antimonates with pyrochlore-like structure are formed with the amount of Sb3+ decreasing on increasing the silver content; and (iv) above 950 degrees C, the silver antimonates decompose giving beta-Sb2O4, which sublimates, and metallic silver. Crystal structure of the silver antimonates has been analyzed; by X-ray diffraction; According to the Rietveld refinement, Ag+ and Sb3+ are placed in the channels of the pyrochlore-like structure.|
|Editor:||Amer Chemical Soc|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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