Characterization of Ultrafine Glassy Powder for Al-Si-Ca-P-O-F Polynary System by Sol-Gel Method

Abstract

The ultrafine bio-glass powder of Si-Al-Ca-P-F-polynary system was prepared by sol-gel method with organic and inorganic compounds such as Si (OC2H5)4, (C2H5)3PO4, Ca (NO3)2·4H2O, Al (NO3)3·9H2O and NH4F. The powder was heat-treated at the different temperature in the range from 200 to 900°C and its crystallized transition was ascertained. The morphology, composition, structure state and crystallized behavior of the glassy powder were characterized by means of TEM, XRD, EDS, DSC-TG, FT-IR etc methods and compared with the glassy powder of the same system by melting-quenching and liquid precipitation. The results show that the powder containing elements Si, Al, Ca, P, F and O belongs to typical amorphous state, and is composed of the near spherical particles with the size from 100 to 400nm; The transition temperature of glass was about 580°C, and the crystallized phase CaF2precipitate firstly above 600°C; A series of crystallized phases Ca5(PO4)3F and Ca5(PO4)2SiO4were separated sequentially with increasing temperature; The network structure of glass is similar to that of melt-quenching or liquid precipitation glass.