Defects occuring in Sr2Nd1.5Ce0.5NbCu2O10-δ have been studied with high resolution electron microscopy and electron diffraction. The structure of Sr2Nd1.5Ce0.5NbCu2O10-δ consists of a block of layers CuO2-SrO-NbO2-SrO-CuO2 having a perovskitelike structure sandwiched with a (Nd, Ce)-O2-(Nd,Ce) block which has a fluorite-like stacking. Defects occur in which the number of (Nd, Ce) layers varies from 1 to 5, e.g. Sr2(NdCe)nNbCu2O6+2n-δ. The n=1 material was found to extend over a relatively larger area. n=2, n=3, n=4 and n=5 phases occur as single planar stacking faults. All n=1, 2, 3, 4, 5 structures have ap√2, ap√2, c superstructure, due to rotation of the NbO6 octahedra about the c-axis. Quite frequently intergrowths occur with an approximate composition of Sr(Nb,Cu)O3, which adopts the perovskite structure with a c-axis of 0.42 nm and with an ab plane which fits to the ab plane of Sr2Nd1.5Ce0.5NbCu2O10-δ. The thickness of the intergrown Sr(Nb,Cu)O3 is limited to 5 nm. The (Nb, Cu)O6 octahedra in Sr(Nb, Cu)O3 are also tilted about the c-axis but the amount of tilt is less than in Sr2Nd1.5Ce0.5NbCu2O10-δ.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering