A suspension is formed by the addition of 5 g of tellurium dust in 25 mL of conc. nitric acid with stirring, an exothermic reaction occurs. After the reaction has been ceased, it is heated with a heating plate until no more gasses arise from the solution, while concentrating the solution until crystals can be seen. The mixture is filtered and the residue is transferred into a crucible, which is heated at 400-430°C for 2 h.
TI + HNO3 = TI2O4⋅HNO3
TI2O4⋅HNO3 = 2 TIO2 + HNO3
Preparation of the fine tellurium dust
The intermediate compound