Journal article

Publication year: 1996

Pages: 1501-1507

Journal: Journal of Inorganic and General Chemistry

Volume number: 622

Issue number: 9

ISSN: 0044-2313

DOI Link: https://doi.org/10.1002/zaac.19966220911

Publisher: Wiley

Abstract: 

Oxidation of the blue-black NbOx phases (2.4 < x < 2.5) in air or a diluted oxygen atmosphere leads all together to 21 metastable colourless (partly yellowish) Nb2O5 modifications. These can be described as compounds having block structures like the NbOx phases themselves. At 200 degrees C the oxidation process to the metastable phases proceeds quite slowly; at higher temperatures all polymorphs are finally transformed to H-Nb2O5.

Electron diffraction patterns of the polymorph, which can be obtained by heating crystals of Nb22O54 in atmospheric environment at about 200 degrees C (Ox1C), show extra spots in the c* direction compared to Nb22O54: This oxidation product is quite sensitive to the focused electron beam, so the reduction of the crystals back to Nb22O54 can only be avoided by reducing its intensity. Finally HRTEM images of thin crystal areas showing a superstructure were obtained. Comparing those characteristic image contrasts to calculated images of different point defect models one finds, that mainly one point defect is responsible for the superstructure. By migration of one Niobium atom two interstitial oxygen sites are created. So a structure model can be achieved leading to the formula Nb44O110.

Harvard Citation style: Prinz, G. and Gruehn, R. (1996) Contributions to the investigation of inorganic non-stoichiometric compounds .44. New electron microscopic investigation of the metastable Nb2O5 modification Ox1C, Zeitschrift für anorganische und allgemeine Chemie = Journal of Inorganic and General Chemistry, 622(9), pp. 1501-1507. https://doi.org/10.1002/zaac.19966220911

APA Citation style: Prinz, G., & Gruehn, R. (1996). Contributions to the investigation of inorganic non-stoichiometric compounds .44. New electron microscopic investigation of the metastable Nb2O5 modification Ox1C. Zeitschrift für anorganische und allgemeine Chemie = Journal of Inorganic and General Chemistry. 622(9), 1501-1507. https://doi.org/10.1002/zaac.19966220911