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Phase Equilibria in the System Na 2 O – Nb 2 O 5
Author(s) -
SHAFER M. W.,
ROY RUSTUM
Publication year - 1959
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1959.tb13562.x
Subject(s) - quenching (fluorescence) , differential thermal analysis , phase (matter) , perovskite (structure) , crystallography , chemistry , analytical chemistry (journal) , materials science , mineralogy , physics , fluorescence , optics , diffraction , organic chemistry , chromatography
Phase equilibria data, obtained both by differential thermal analysis and by quenching, are presented for the system Na 2 O‐Nb 2 O 5 . Five compounds corresponding to the formulas 3Na 2 O.1Nb 2 0 6 , lNa 2 O. 1Nb 2 O 5 , lNa 2 O 4Nb 2 O 6 , lNa z O.7Nb 2 O 5 , and lNa 2 O. 10Nb 2 O 6 have been found. The compound 3Na z 0.lNb 2 O 5 melts congruently at 992°C. The compounds 1Na 2 O. 4Nb 2 O 6 , lNa 2 O.7Nb 2 O, and 1Na 2 O. 1Onb 2 O 5 melt incongruently at 1265°, 1275°, and 1290°C., respectively. The well‐known perovskite structure phase NaNbO 3 was found to melt congruently at 1412°C. The transition temperatures in NaNbO 5 were checked by thermal analysis and only the major structural changes at 368° and 640°C. could be detected. A new disordered form of NaNbO 3 could be preserved to room temperature by very rapid quenching.