Publication Type:Journal Article
Source:Applied Physics Letters, Volume 53, Number 7, p.615-617 (1988)
Results of high-resolution electron microscopy, convergent beam electron microscopy, and x-ray microanalysis on the high Tc phase are reported. Local inhomogeneities in the structure and composition have been observed along the c direction. Both c=30.56 Å (8ap) and c=38.2 Å (10ap) have been observed inside the same grain. The regions with the larger c parameter correspond to regions with higher Ca and Cu concentration suggesting that the range of transition temperatures observed (85 to 115 K) is due to the coexistence of such regions of c=38.2 Å and c=30.56 Å.
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