Study on the decomposition of the crystalline phase Na₂O·8TeO₂

The new crystalline phase was found in the Na₂O·TeO₂ system, Na₂O·8TeO₂, (NT₈) was heated at different temperatures for different time and the crystalline phase in the different samples were analyzed. The mechanism of the decomposition for the Na₂O·8TeO₂ was explored and discussed in detail. Results show that the NT₈ is stable below 330°C and will decompose into two crystalline phase: Na₂O·4TeO₂ and TeO₂. There are two thermal effects found during the decomposition of NT₈: one is the endothermal and the other exothermal, indicating that one amorphous phase formed during the decomposition of NT₈. It is believed that the decomposition of NT₈ happened according the following two steps: first the NT₈ is transformed into an amorphous phase and then the amorphous phase is transformed into NT₄ and TeO₂.