ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The crystal and defect structure of neodymium cerium cu-prate (Nd1.9 Ce0.1 CuO4±y) has been studied as a function of temperature (1200–1500 K) and oxygen pressure (100–103 atm) via X-ray diffractometry, powder neutron diffraction, and thermogravimetry methods. The oxygen nonstoichiom-etry changes from oxygen-excess (positive y values) to oxygen- deficient oxides (negative y values). The absolute values of oxygen nonstoichiometry y are calculated from the neu-tron diffraction and thermogravimetry data. The materials adopt the tetragonal structure (space group I4/mmm). A defect model is proposed for Nd2-x Cex CuO4±y. It is con-cluded that oxygen vacancies VÖ (which occupy O(1) crys-tallographic positions (in planes)) and interstitial oxygen O(i (which occupy O(3) “apical” positions) are present simultaneously. Gaseous oxygen intercalates into the Nd1.9 Ce0.1 CuO4±y crystals and replaces oxygen vacancies in the O(1) position and interstitial oxygen atoms in the O(3) positions. The theoretical model and the experimental data are in good agreement with each other, and the equilibrium constants of defect formation have been calculated.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.1999.tb01870.x
