Synthesis of nanocrystalline forsterite fiber via a chemical route

Forsterite gel fibers were drawn from acetic acid-modified viscous solutions prepared by alkoxide sol-gel processing. The crystallization behavior and microstructural evolution of the gel fibers were investigated. Besides enhancing spinnability, an appropriate amount of acetic acid also increased the intimate mixing of the condensed species, significantly reducing the crystallization temperature of forsterite, although X-ray diffraction revealed some inhomogeneity. Thermal analysis and X-ray diffraction revealed that gel fibers began crystallizing into forsterite at 550°C. Furthermore, the infrared spectra on heating gel fibers indicated that further condensation might occur between the silanol groups and the decomposition of the acetate ligand groups. On heating to 800°C, forsterite ceramic fibers exhibited nanocrystals of approximately 20–30 nm in size, and the nanocrystalline structures remained up to 1100°C; further heating to 1300°C caused grain size growth to 0.3–0.5 μm, with a dielectric constant of around 7.2±0.6, at 1 MHz.