Preparation of HfSiO4 via Non-Hydrolytic Sol-Gel method at low temperatures

Abstract

Hafnon (HfSiO4) can be applied in electronics, dielectric films, refractory materials, and many other critical application areas. To explore an efficient preparation process of HfSiO4, a novel non-hydrolytic sol-gel (NHSG) method was used to synthesize high-purity HfSiO4 in this study. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), thermogravimetric differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FT-IR), and infrared thermal imaging (ITI) were used to investigate the synthesis temperature and mechanism of HfSiO4 and the effects of process parameters on its synthesis efficiency. The results show that the prepared sols undergo a highly reactive non-hydrolytic polycondensation reaction at room temperature. High temperature reflux or long time aging step is not necessary to form the strong Hf-O-Si bonds. Furthermore, with the introduction of the mineralizer agent LiF, the synthesis temperature of HfSiO4 can be drastically reduced, and the HfSiO4 with high purity can be synthesized at low temperatures. A moderate molar ratio of silicon to hafnium (Si:Hf) and molar concentration of the solution contribute to improve the synthesis efficiency of HfSiO4, and the purity of HfSiO4 products can reach up to 98.12 %.