| Journal: | Materials research |
| Database: | PERIÓDICA |
| System number: | 000312959 |
| ISSN: | 1516-1439 |
| Authors: | Soares, Robson de Miranda1 Sabioni, Antonio Claret Soares Resck, Ines Sabioni2 Falcomer, Viviane Aparecida Silva Dias, Jose Alves Silva, Naira Machado da3 Menezes, Sonia Maria Cabral de4 Costa, Geraldo Magela da5 |
| Institutions: | 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 |
| Year: | 2007 |
| Season: | Ene-Mar |
| Volumen: | 10 |
| Number: | 1 |
| Pages: | 75-78 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Nota breve o noticia |
| Approach: | Experimental |
| English abstract | 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 |
| Disciplines: | Ingeniería, Química |
| Keyword: | 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 |
| Full text: | Texto completo (Ver HTML) |
