Structural characterization of mullites synthesized by thermal decomposition of topaz



Título del documento: Structural characterization of mullites synthesized by thermal decomposition of topaz
Revista: Materials research
Base de datos: PERIÓDICA
Número de sistema: 000312959
ISSN: 1516-1439
Autores: 1

2


3
4
5
Instituciones: 1Universidade Federal de Ouro Preto, Departamento de Fisica, Ouro Preto, Minas Gerais. Brasil
2Universidade de Brasilia, Instituto de Quimica, Brasilia, Distrito Federal. Brasil
3Pontificia Universidade Catolica do Rio de Janeiro, Rio de Janeiro. Brasil
4Petroleo Brasileiro S.A., Rio de Janeiro. Brasil
5Universidade Federal de Ouro Preto, Departamento de Quimica, Ouro Preto, Minas Gerais. Brasil
Año:
Periodo: Ene-Mar
Volumen: 10
Número: 1
Paginación: 75-78
País: Brasil
Idioma: Inglés
Tipo de documento: Nota breve o noticia
Enfoque: Experimental
Resumen en inglés The structure of mullite obtained by thermal decomposition of topaz at 1340 °C and after additional thermal treatment at 1600 °C was characterized by 29Si and 27Al MAS NMR spectroscopy and x ray diffraction. No amorphous phase was detected by these techniques. The 29Si MAS NMR spectra of the mullite samples showed four resonance peaks at -81, -86, -90 and -94 ppm. The peak at -81 ppm corresponded to silicon near oxygen vacancies in the mullite structure. The peak at 86 ppm was related to a sillimanite-type site and was the major contribution, ranging from 42 to 50%. The two other peaks, at -90.0 ppm and -94 ppm, were interpreted as resulting from rearrangements of the sillimanite-type site by the replacement of AlO4 by SiO4 tetrahedra16. The 27Al MAS NMR data of the two samples exhibited three different peaks, two of which were attributed to tetrahedral sites at 40 -45 and 63 -67 ppm, while the third was assigned to an octahedral site at about -6 ppm. The ratio of tetrahedral to octahedral aluminum sites was found to depend on the temperature applied during the preparation of the mullite and was higher at 1600 °C
Disciplinas: Ingeniería,
Química
Palabras clave: Ingeniería de materiales,
Química industrial,
Mullita,
Topacio,
Síntesis química,
Tratamiento térmico,
Cerámica
Keyword: Engineering,
Chemistry,
Materials engineering,
Industrial chemistry,
Mullite,
Topaz,
Chemical synthesis,
Thermal treatment,
Ceramics
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