resumo
Different macroscopic properties of PZT fibers have been obtained when using acetic acid and methacrylic acid to modify the PZT precursor. In order to clarify the role of the acids the molecular structure of the acidified PZT precursors was investigated and compared by gas chromatography-mass spectrometry, Fourier transform infrared, C-13 nuclear magnetic resonance (NMR) spectroscopy (solution and solid state C-13 NMR) and the reason for obtaining long PZT fibers is discussed. The results indicate that when methacrylic acid was used, long gel and ceramic fibers have been obtained because strongly co-ordinating carboxylate groups of methacrylic acid were formed. Linear chains, like those of methacrylic acid propyl ester and methacrylic acetate, have been formed in the PZT precursor sols. In addition, after heat treatment the polymer decomposed quickly so that pure perovskite could be obtained at low temperature in the PZT fibers. When acetic acid was used short fibers were obtained. Acetic acid may act as chelate agent to form oxo acetate in the precursors; this oxo acetate nature also resulted in PZT fibers drawing. However, the longest gel and ceramic fibers have been prepared from precursors with methacrylic acid.
palavras-chave
THIN-FILMS; CERAMIC FIBERS; POLYMER; PBTIO3; GELS; H-1
categoria
Materials Science
autores
Zhang, M; Salvado, IMM; Vilarinho, PM; Silvestre, AJD; Silva, AMS
nossos autores
Armando Jorge Domingues Silvestre
Professor Catedrático
Isabel Margarida Miranda Salvado
Professor associado