In:
Modern Physics Letters B, World Scientific Pub Co Pte Ltd, Vol. 02, No. 03n04 ( 1988-05), p. 621-628
Abstract:
A series of samples with the nominal composition Ba 2 ( Ba 1−x La x ) Cu 3 O 7−y , (0≤x≤1), was synthesized by solid state reaction. An X-ray diffraction study showed that a continuous solid solution exists between Ba 2 YCu 3 O 7−y and Ba 2 LaCu 3 O 7−y and there is a composition induced order-disorder transition from an orthorhombic to a tetragonal structure when x value is near 0.9. All the samples with orthorhombic crystal structure are superconductors with T c onset above 90K. The transition midpoint temperature decreases smoothly when La content increases. The samples with x≥0.9 have a tetragonal structure and show semiconductor behavior with an exception of the x=1.0 sample which is a superconductor. Based on our previous and present studies, we concluded that the low dimensional character of the crystal structure and the mixed-valence state of copper or oxygen are necessary conditions for high-T c superconductivity in copper-containing oxides.
Type of Medium:
Online Resource
ISSN:
0217-9849
,
1793-6640
DOI:
10.1142/S0217984988000254
Language:
English
Publisher:
World Scientific Pub Co Pte Ltd
Publication Date:
1988
