Oxygen vacancies in Nb$sub 22$O/sub 54-x/, Nb$sub 25$O/sub 62-x/, and Nb$sub 2$$sub 8$O/sub 70-x/

Journal Article · Mon Dec 01 04:00:00 EST 1975 · J. Solid State Chem., v. 15, no. 4, p. 371

OSTI ID:4018313

Kikuchi, T; Goto, M

The isolated oxygen vacancies in Nb$sub 22$O/sub 54 - x/, Nb$sub 25$O/ sub 62 - x/, and Nb$sub 2$$sub 8$O/sub 70 - x/ at temperatures above 1300$sup 0$C were examined thermodynamically using gravimetric data obtained previously by Kimura. The concentration of oxygen vacancies in Nb$sub 22$O/sub 54 - x/ and Nb$sub 25$O/sub 62 - x/ was estimated from isothermal changes in weight and found to be proportional to Po$sub 2$/sup -$sup 1$$/$$sub 2$/. With Nb$sub 2$$sub 8$O/ sub 70 - x/, on the other hand, the concentration of oxygen vacancies was proportional to Po$sub 2$/sup -$sup 1$$/$$sub 4$/. These results can be explained well on the assumption that the main defects, which all depend upon the partial pressure of oxygen in the surrounding atmosphere, are oxygen vacancies with one trapped electron, quasifree electrons, and tetravalent niobium atoms.

• Research Organization: Inst. for Researches in Inorganic Materials, Ibaraki, Japan
• NSA Number: NSA-33-026493
• OSTI ID: 4018313
• Journal Information: J. Solid State Chem., v. 15, no. 4, p. 371, Journal Name: J. Solid State Chem., v. 15, no. 4, p. 371; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

*NIOBIUM-- VACANCIES
360202* --Materials--Ceramics
Cermets & Refractories-- Structure & Phase Studies
DEFECTS
ISOTHERMAL PROCESSES
N50130* --Metals
Ceramics
& Other Materials--Ceramics & Cermets--Properties
Structure & Phase Studies
PRESSURE DEPENDENCE
STOICHIOMETRY
VERY HIGH TEMPERATURE