Direct synthesis of pure brannerite UTi2O6

Abstract A new method based on the precipitation of uranium(IV) and titanium(IV) hydroxide precursors was developed to prepare pure brannerite UTi 2 O 6 samples. In fact, U(IV) dissolved in HCl (6 mol L −1 ) was mixed to Ti (IV) alkoxyde before a basification step with an excess of NH 4 OH to obtain a highly reactive nanometric (U,Ti)(OH) 4 powder. The obtained powder was then dried under vacuum, pressed into pellets and finally fired at 1300 °C. This method led to the formation of pure brannerite in contrast to previous reported protocols, which showed the formation of impurities such us UO 2 and TiO 2 . The refined unit cell parameters of UTi 2 O 6 led to a  = 9.8113(2) A, b  = 3.7681(1) A, c  = 6.9232(1) A, β  = 118.94(1)° and V  = 223.9(1) A 3 .