INVESTIGADORES
CANEIRO Alberto
artículos
Título:
Thermogravimetric study of the tungsten-oxygen system in the range 2.89
Autor/es:
A. CANEIRO
Revista:
SOLID STATE IONICS
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 1992 vol. 50 p. 107 - 114
ISSN:
0167-2738
Resumen:
Measurements of the partial pressure of oxygen (P,,) in the tungsten-oxygen system have been performed by a thermogravimetrictechnique in the composition range 2.89 <O/W < 3.00 between 1023 and 1223 K. Measurements at 1123 K show a substantialhysteresis of Po, as a function of composition. In spite of this effect, useful thermodynamic information on the nature ofthe phase diagram can be extracted. The homogeneity range of the W03+. phase is 2.99 <O/W c 3.00. As Po, decreases, a compoundis detected around O/W=28975 corresponding to the Wz005s phase. When PO, is increased to over 5.82~ lo-l2 kPa,W2,,0s8 is oxidized indicating the formation of an intermediate phase of composition close to O/W = 2.975, the stability of whichis confined to only a short PO2 range. The partial molar entropy and enthalpy of solution of oxygen in the WOs_, phase have alsobeen evaluated and are discussed.
