caa a22 4500 386400938 CHVBK 20180307112158.0 cr unu---uuuuu 161130e198909 xx s 000 0 eng 10.1017/S0885715600016626 doi S0885715600016626 pii (NATIONALLICENCE)cambridge-10.1017/S0885715600016626 A Study of the Superconducting La2-xSrxCuO4 System by X-Ray Powder Diffraction [Elektronische Daten] Room temperature crystalline structures of La2-xSrxCuO4 samples with uncommonly high hole concentrations (p) up to p=0.4, annealed under 1 and 100 bars of oxygen pressure have been analyzed by X-ray diffraction. Results show that the x=0 sample with p=0.09 and superconducting below 20K is orthorhombic at room temperature. The orthorhombic distortion at 300K decreases with increasing x and becomes tetragonal when x reaches 0.08. This orthorhombic-to-tetragonal phase transformation is consistent with previous work. Samples with x≥0.28 and p≥0.31 remain tetragonal but are nonsuperconducting down to 5K. Lattice dimension anomalies have also been observed and are correlated with the sudden appearance of oxygen vacancies, as seen by the hole concentration measurements. Initially, the value of the lattice dimension a decreases and c increases monotonically with increasing x. A sudden increase in a and decrease in c begins when x reaches 0.28 for samples prepared under 1 bar of oxygen indicating a sudden loss of oxygen from the structure. This sudden reversal in lattice dimensions a and c is not present in samples annealed under 100 bars of oxygen pressure suggesting essentially no oxygen vacancies. The increase in c with x of the La2-xSrxCuO4 samples with no oxygen vacancies can be attributed mainly to the result of substituting smaller La+3 ions by larger Sr+2 ions. A study of the variation of c with the hole concentration reveals that the c lattice dimension drops sharply with no change in the hole concentration when oxygen is continuously removed from the lattice caused by an increase of the Sr content in La2-xSrxCuO4. Copyright © Cambridge University Press 1989 Huang T.C. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A. Torrance J.B. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A. Nazzal A.I. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A. Tokura Y. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A. Powder Diffraction Cambridge University Press 4/3(1989-09), 152-155 0885-7156 4:3<152 1989 4 PDJ https://doi.org/10.1017/S0885715600016626 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1017/S0885715600016626 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Huang T.C. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A NATIONALLICENCE 700 1- Torrance J.B. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A NATIONALLICENCE 700 1- Nazzal A.I. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A NATIONALLICENCE 700 1- Tokura Y. IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, U.S.A NATIONALLICENCE 773 0- Powder Diffraction Cambridge University Press 4/3(1989-09), 152-155 0885-7156 4:3<152 1989 4 PDJ CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-cambridge