Thermogravimetric Study of theLn2O3–Co–Co2O3System: V.Ln=Nd at 1100 and 1150°C

✍ Scribed by Kenzo Kitayama

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 264 KB
• Volume: 137
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7726

✦ Synopsis

Phase equilibria in the system Nd-Co-O at 1110 and 1150°C are established by changing the oxygen partial pressure from 0 to 12.00 in!log(P O 2 /atm) and phase diagrams are presented for the Nd 2 O 3 -Co-Co 2 O 3 system. Under the experimental conditions, Nd 2 O 3 , CoO, Co, Nd 4 Co 3 O 10 , and NdCoO 3 phases are present at both temperatures. The nonstoichiometry of the compounds Nd 4 Co 3 O 10 and NdCoO 3 is represented with respect to the oxygen partial pressure, and activities of the components in the solid solutions are calculated using the composition-oxygen partial pressure relations obtained. The changes of the standard Gibbs energies of the reactions in the phase diagrams are calculated and their linearity with temperature is confirmed under the present experimental conditions. The relationship between the change of the standard Gibbs energy of a reaction and the ionic radius of the lanthanoid element is discussed.