Sketch the phase diagram for Na2O-Nb2O5 using the following information and label all regions on the diagram. Indicate the peritectic line and what exist in that line.

 • Four compounds are stabilized from Na2O and Nb2O5 mixture.

 • Na3NbO4 melts congruently at 992 °C. 

 • NaNbO3 melts congruently at 1412 °C.

 • NaNbO3 undergoes phase transition at 368 (α to β phase) and 640 °C (β to g phase)

 • Na2Nb8O21 melts incongruently at 1265 °C to (Na2Nb20O51 + liquid) 

 • Na2Nb20O51 melts incongruently at 1290 °C to (Nb2O5 + liquid)

 • Na2O melts at 1200 °C • Nb2O5 melts at 1485 °C

 • Eutectics at: 

 - 10% Nb2O5 at 830 °C

 - 31% Nb2O5 at 975 °C

 - 68% Nb2O5 at 1220 °C 

(Hint: Na2O + Nb2O5 -> 2NaNbO3.)