Thermodynamic properties of titanium dioxide, niobium dioxide and their solid solutions at high temperature

Journal Article · Tue Jan 01 04:00:00 EST 1985 · J. Polym. Sci.; (United States)

DOI:https://doi.org/10.1016/0022-3697(85)90160-X· OSTI ID:6488694

Marucco, J-F; Gautron, J; Lemasson, P; Poumellec, B

By means of thermogravimetric measurements, it has been possible to obtain information on the nature of the intrinsic and extrinsic defects of TiO/sub 2/, NbO/sub 2/ and solid solutions Nb /SUB y/ Ti /SUB 1-y/ O /SUB 2+or-x/ . Pure TiO/sub 2/ is an oxygen-deficient oxide. The main defects are oxygen vacancies, doubly ionized V /SUP ../ /SUB o/ or singly ionized V /SUP ./ /SUB o/ , and interstitial titanium Ti /SUP 3./ /SUB i/ . NbO/sub 2/ is a metal-deficient oxide. The main defects are neutral niobium vacancies. The solid solutions Nb /SUB y/ Ti /SUB 1-y/ O /SUB 2+or-x/ may be divided into two groups. I y > 0.04, the behavior is analogous to that of NbO/sub 2/ with the same defects, but the width of the homogeneity range decreases with the titanium content and Nb /SUB 0.04/ Ti /SUB 0.96/ O/sub 2/ is a stoichiometric oxide. If y < 0.04, the oxides are both metal deficient and oxygen deficient according to the oxygen partial pressure. We have particularly studied the solution Ti /SUB 0.995/ Nb /SUB 0.005/ O/sub 2/. In the oxygen-deficient domain, the main defects are assumed to be neutral or singly ionized oxygen vacancies. In the metal-deficient domain, the main defects are metal vacancies V /SUP 4'/ /SUB Ti/ . From these results we have deduced the nature of intrinsic defects in TiO/sub 2/ to be Schottky defects: 2V /SUP ../ /SUB o/ + V /SUP 4'/ /SUB Ti/ .

• Research Organization: Laboratoire des Composes non Stoechiometriques, ERA 680 du CNRS, Universite de Paris XI, Orsay
• OSTI ID: 6488694
• Journal Information: J. Polym. Sci.; (United States), Journal Name: J. Polym. Sci.; (United States) Vol. 46:6; ISSN JPSCA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360204* -- Ceramics
Cermets
&amp; Refractories-- Physical Properties
CHALCOGENIDES
CHEMICAL ANALYSIS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISPERSIONS
ELEMENTS
GRAVIMETRIC ANALYSIS
IONIZATION
METALLURGICAL EFFECTS
MIXTURES
NIOBIUM COMPOUNDS
NIOBIUM OXIDES
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PARTIAL PRESSURE
PHYSICAL PROPERTIES
POINT DEFECTS
QUANTITATIVE CHEMICAL ANALYSIS
REFRACTORY METAL COMPOUNDS
SCHOTTKY DEFECTS
SOLID SOLUTIONS
SOLUTIONS
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
VACANCIES