Novel sea-urchin-like rutile microstructures synthesized by the thermal decomposition and oxidation of K2TiF6

Sea-urchin-like rutile (su-TiO2) microstructures were successfully synthesized by thermal decomposition and oxidation of a solid precursor, K2TiF6. During the synthesis, precursor temperature (640 C), N-2-flow (15 cm(3)/min) and inner pressure (90 mbar above the atmospheric pressure) remained constant. In order to evaluate the effect of time on the morphology of su-TiO2, five levels (0.5, 1, 1.5, 2, and 2.5 h) were considered. The thermal decomposition an oxidation of the K2TiF6 precursor was studied by thermal analyses. It was found that TiO2 was segregated from the matrix, leading to the formation of su-TiO2 during processing. At 640 C, the precursor underwent thermal decomposition and oxidation that produced three different products: K3TiOF5(s)(5), TiO2(s)(,), and F-2(g)(g). The su-TiO2 is synthesized only at t=2 h and t=2.5 h, presenting defined spikes at the former (100 mu m Chi 100 mu m) and rougher structures at the latter (50 mu m Chi 10 mu m). (C) 2014 Elsevier B.V. All rights reserved.