THERMOGRAVIMETRIC STUDY OF THE NON-STOICHIOMETRIC WÜSTITE FeOX. PSEUDO PHASES W i AND W' i . NEW T-P-X EQUILIBRIUM PHASE DIAGRAM

Auteurs initiaux en 1979Traduction par Claude Carel, auteur initial,les deux mêmes auteurs que pour hal-03083695CONTRIBUTION A L'ETUDE DU MONOXYDE DE FER SOLIDE NON-STOECHIOMETRIQUE. DIAGRAMME T-P-X.Pierre Vallet (1906-1994), Claude Carel, Mat. Res. Bull. 14, pp.1181-1194, 1979. 0025-5408/79/091181-14$02.00/0 Pergamon Press Ltd. (publisher Elsevier) doi.org/10.1016/0025-5408(79)90213-7//doi.org/10.1016/0025-5408(79)90213-7.ABSTRACT A statistical numerical analysis of thermogravimetric measurements (temperature, mass variation, oxygen pressure) leads to a new equilibrium phase diagram T-P-X of the iron monoxide or wüstite FeOx. Three varieties or pseudo phases W1, W2, W3 are revealed above 911 °C, three others W’1, W’2, W’3 below. This diagram displays their subfields, and shows 25 invariant points between stable phases and 8 possible invariant points between metastable phases. A thermodynamic approach is pointed out, which makes possible to characterize the point defects and their clusters as components of the crystal lattice. ADDENDA and comments in 2021. KEY WORDS: thermogravimetry, high temperatures, thermodynamic equilibrium, second-order transitions, triple points, phase diagra