Shock synthesis and characterization of titanium dioxide with α-PbO₂ structure

The phase transformation behavior of anatase and rutile titanium dioxide with particle sizes of 60 nm and 150 nm under shock compression have been investigated. To increase the shock pressure and reduce the shock temperature, copper powder and a small amount of paraffin were mixed with the TiO₂ powder. The shock recovered samples were characterized by x-ray diffraction, Raman spectroscopy, and transmission electron microscope. The results indicate that both anatase and rutile TiO₂ can transform to α-PbO₂ phase TiO₂ through shock-induced phase transition. The transformation rate of α-PbO₂ phase TiO₂ for anatase TiO₂ under shock compression is 100% and pure α-PbO₂ phase TiO₂ can be obtained, while the transformation rate for rutile TiO₂ is over 90%. The influence of the particle size on the yield of α-PbO₂ phase TiO₂ is not noticeable. The thermal stability of the recovered pure α-PbO₂ phase TiO₂ was characterized by high temperature x-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The results show that α-PbO₂ phase TiO₂ transforms to rutile TiO₂ when heated to temperature higher than 560 °C. The mechanisms of the phase transition of TiO₂ under shock compression are discussed.