The microstructure and defects of the n = 2 Ruddlesden-Popper manganites La2-

2xCa1+2xMn2O7 (x = 0.6, 0.8 and 0.9) were investigated by electron diffraction and

high-resolution transmission electron microscopy. Besides the predominant n = 2

layered structure in the examined compounds, intergrowths with different numbers

of perovskite-like layers were observed. Intergrowth of n = 1 (K2NiF4-type) was

observed only in the x = 0.9 sample. Intergrowths with n greater than 5, essential

perovskite micro-domains or inclusions, were seen in the x = 0.8 and 0.6 samples.

The type of defect in the x = 0.8 sample was much richer than that in x = 0.6 and 0.9 samples and two rare types were observed and analyzed. Some edge

dislocations were present in the x = 0.6 specimen.

Microstructure and Defect Investigations of the Layered Manganites La2-2xCa1+2x

Mn2O7 (X = 0.6, 0.8 and 0.9) by HREM. Y.Wang, R.Yu: Physica Status Solidi A,

2009, 206[1], 31-5