Equilibrium and non-equilibrium phase diagram within the TeO2-rich part of the TeO2-Nb2O5 system
The TeO 2 -rich part of the TeO 2 -Nb 2 O 5 system has been investigated by temperature programmed X-ray diffraction and differential scanning calorimetry. Three invariant equilibria have been observed: one eutectic reaction (8 mol% NbO 2.5 , T E =690±5 °C, L E TeO 2 +Nb 2 Te 4 O 13 ), one peritectic reaction (incongruent melting, at 766±5 °C, of the Nb 2 Te 4 O 13 compound) and one congruent melting reaction (congruent melting, at 810±5 °C, of the Nb 2 Te 3 O 11 compound). A large glass-forming domain has been evidenced (0 to 25 mol% NbO 2.5 ). The thermal behaviour of these glasses has been followed. The glass transition, crystallization temperatures and the nature of crystalline phases formed have been determined.
