Efeito da reatividade de precursores na sintese de fosfatos com estrutura tipo Nasicon

AUTOR(ES)

Francisco Manoel dos Santos Garrido

DATA DE PUBLICAÇÃO

1995

RESUMO

In this work the preparation of Nasicon like phosphates is describe. The following synthetic methods were used: a) Traditional Ceramic Method; b) Zirconium Phosphate Xerogel Reaction Method; c) Layered Phosphate Reaction Method and d) Sol-Gel Method. The influence of the precursors reactivity on the synthesis was the main aspect studied. XRD, IR technics were used to identify the phases formed in the intermediate steps. XRD, IR and NMR P (MAS) data are used to discuss structural and stoichiometric aspects of this family. New synthetic routes, to the preparation of M containing phases, were developed (Layered Phosphate Reaction and Sol-Gel Methods), and new phases were prepared with the following nominal stoichiometry: i) Na0,64Nb0,64Zr1,29(PO4)3; ii)V0,6Zr1,5 (PO4)3 iii) Na1,5 Nb0,3Zr1,5 (PO4)3 and iv) NbZr(PO4)3. (The latter with a monoclinic structure.) Preliminary measurements of the thermal expansion coefficient in ceramic bodies, prepared with the phases synthesized by methods (a) and (b), were made. The results suggest that the new phases (i) and (ii), can be potentially useful in the preparation of ceramics with low thermal expansion coefficients.

ASSUNTO(S)

reações quimicas reatividade (quimica) fosfatos

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