Accession Number:

AD0773175

Title:

Gravimetric and Electrical Conductivity Studies of Pure and Doped Niobium Pentoxide.

Descriptive Note:

Final rept.,

Corporate Author:

SYSTEMS RESEARCH LABS INC DAYTON OHIO

Personal Author(s):

• Tripp,Walter C.
• Wimmer,J. M.

Report Date:

1973-11-01

Pagination or Media Count:

35.0

Abstract:

Thermogravimetric and electrical conductivity measurements on alpha Nb2O5 were made over the temperature range 900-1300 degree C in COCO2 mixtures and in pure oxygen. Anomalous conductivity results at low PO2 suggest the presence of nonstoichiometric phases. The data at higher PO2 are analyzed on the basis of a defect model consisting of impurity control of the oxygen vacancy concentration at high PO2 with a transition to a predominance of electrons and fully ionized oxygen vacancies at lower PO2. The mobility, obtained by combining gravimetric and conductivity data, is shown to have negative temperature dependence with a value of 0.15 sq. cmV-sec at 1000C. A value of -175 kcalmole is obtained for the partial molar enthalpy of oxygen in Nb2O5-x over the range of x from 0.0025 to 0.01. Modified author abstract

Descriptors:

• OXYGEN
• DEFECTS(MATERIALS)
• STOICHIOMETRY
• DOPING
• ALUMINUM
• TUNGSTEN
• IRON
• ZIRCONIUM

Subject Categories:

• Solid State Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE