Tantalum Dioxide, TaO₂

Tantalum Dioxide, TaO₂, has been prepared as a dark brown powder by heating rods made of a mixture of tantalum pentoxide and paraffin in powdered charcoal at about 1700° C., or by reducing the pentoxide at a high temperature with magnesium. It is stated to be formed also during the electrolysis of solutions of salts of the metals using a tantalum anode. On being heated in air it takes up oxygen and forms the pentoxide. It is insoluble in acids, but dissolves in molten potassium hydroxide to form potassium tantalate.