Kinetics of oxidation of phi-phase terbium oxide: 7/2Tb/sub 2/O/sub 3+delta/ + (3/4 - 7/4 delta)O/sub 2/. -->. Tb/sub 7/O/sub 12/

Journal Article · Sat Nov 14 23:00:00 EST 1981 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/0022-4596(81)90380-7· OSTI ID:5769866

Sugihara, T; Lin, S H; Eyring, L

Kinetic and thermodynamic studies of the terbium oxides between the Tb/sub 2/O/sub 3+delta/ (n = 4) and Tb/sub 7/O/sub 12/ (n = 7) phases of the homolgous series, Tb/sub n/O/sub 2n-2/, have been carried out as a function of oxygen pressure at 708, 740, 772, and 806/sup 0/C. The thermodynamic study shows a reproducible hysteresis loop which depends on the temperature and pressure. The kinetic study was carried out by measuring the weight gain of an oxide sample in an oxygen atmosphere as a function of time. The results are interpreted by a mixed-model mechanism of diffusion and phase boundary reaction control. The relative fit of the data with other models, including the phenomenological model previously found satisfactory for a related reaction, is shown. The kinetics in the final stage are strongly affected by the existence of pseudophase behavior near Tb/sub 7/O/sub 12/. From measurement of the oxygen pressure and temperature dependence of the observed rate constants, the activation energies for the diffusion process and phase boundary reaction process were determined to be -14 and 10 kcal/mole, respectively.

• Research Organization: Arizona State Univ., Tempe
• OSTI ID: 5769866
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 40:2; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DATA
DIFFUSION
EXPERIMENTAL DATA
INFORMATION
KINETICS
LOW PRESSURE
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
RARE EARTH COMPOUNDS
REACTION KINETICS
TERBIUM COMPOUNDS
TERBIUM OXIDES
THERMODYNAMICS
VERY HIGH TEMPERATURE