On synthesis of orthotelluric acid and its thermal and radiation stability

Thermal stability of orthotelluric acid has been studied using the methods of differential-thermal and thermogravimetric analyses. Orthotelluric acid is thermally stable up to 403 K. During subsequent heating a stepped dehydration takes place and then formation of TeO2 at 843 K. It is shown that increased gamma-background affects in a negative way the radiation stability of orthotelluric acid, and its prolonged irradiation (beyond 30 days) under reactor conditions (at thermal neutron flux approximately 5x1013 cm-2xs-1 and γ-background 7x105 R/s) can result in practically complete decomposition. Autoradiolysis of radioactive orthotelluric acid does not lead to a considerable change of the state. During the synthesis of H6TeO6 with hydrogen peroxide 5-6% tellurium in tetravalent state appears