Fabrication of rutile rod-like particle by hydrothermal method: an insight into HNO 3 peptization

Abstract

In this work, well-crystallized and well-dispersed rod-like TiO 2 rutile particles were prepared by hydrothermally treating acid-peptized TiO 2 sols at relatively low temperatures of 200 and 240 °C. Raman spectra, transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize the peptized sols before and after hydrothermal treatment. The results showed that HNO 3 peptization of amorphous TiO 2 was able to promote, at room temperature, the formation of crystalline phases of anatase or rutile, at low ( HNO 3 /Ti = 1 ) or at high ( HNO 3 /Ti = 4 ) concentrations of peptizer, respectively. However, after hydrothermal treatment, well-crystalline rutile developed independent of the starting concentration of the peptizer. The formation of well-dispersed rutile particles is attributed to high long-range electrostatic forces between particles in the presence of the high concentration of the peptizer. The acid peptization would easily break the oxolation bonds between Ti O Ti , promote the formation of titanium species with fewer oxolation bonds depending on the amount of acid, and create conditions for the formation of rutile nuclei after structural rearrangements.