TY - JOUR
T1 - Microscopic Studies on Y2Ba4Cu7O15-δby Use of TEM and NQR Techniques
AU - Kato, Masaki
AU - Nakanishi, Makoto
AU - Miyano, Toshio
AU - Shimizu, Tadashi
AU - Kakihana, Masato
AU - Yoshimura, Kazuyoshi
AU - Kosuge, Koji
N1 - Funding Information:
The authors are grateful to Mr. T. Ohmura and Mr. H. Kato for their kind help in the experiments. The authors are also indebted to Mr. M. Suzuki for his assistance in TEM experiments. This work was partially supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture of Japan.
PY - 1998/9
Y1 - 1998/9
N2 - Y2Ba4Cu7O15-δcompounds were characterized by microscopic investigation using TEM and NQR techniques. We synthesized Y247 compounds by two kinds of preparation methods: the conventional solid-state reaction (sample A) and the polymerized-complex method (sample B). The value ofTcfor sample A was found to be 65 K and that for sample B was 93 K by ac-χmeasurements. As a result of TEM experiments, stacking faults along thecaxis were observed more frequently in sample B than in sample A. These stacking faults resulted in microdomains containing pure Y123 or Y124 thin blocks of several unit cells. NQR experiments revealed that the microscopic environment of Cu(2) sites in sample A differed from either of those in the Y123 and Y124 compounds. NQR frequency values (νQ) of Cu(2) sites agreed well with those calculated by the point charge model applied for the Y247 structure. The spectra of Cu(2) sites in sample B could be regarded, however, as a combination of those of pure Y123, Y124, and also Y247 compounds. This fact was coincident with the result of TEM experiments. We concluded that the superconductivity of Y247 with higherTcoriginates from the thin block of Y123.
AB - Y2Ba4Cu7O15-δcompounds were characterized by microscopic investigation using TEM and NQR techniques. We synthesized Y247 compounds by two kinds of preparation methods: the conventional solid-state reaction (sample A) and the polymerized-complex method (sample B). The value ofTcfor sample A was found to be 65 K and that for sample B was 93 K by ac-χmeasurements. As a result of TEM experiments, stacking faults along thecaxis were observed more frequently in sample B than in sample A. These stacking faults resulted in microdomains containing pure Y123 or Y124 thin blocks of several unit cells. NQR experiments revealed that the microscopic environment of Cu(2) sites in sample A differed from either of those in the Y123 and Y124 compounds. NQR frequency values (νQ) of Cu(2) sites agreed well with those calculated by the point charge model applied for the Y247 structure. The spectra of Cu(2) sites in sample B could be regarded, however, as a combination of those of pure Y123, Y124, and also Y247 compounds. This fact was coincident with the result of TEM experiments. We concluded that the superconductivity of Y247 with higherTcoriginates from the thin block of Y123.
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U2 - 10.1006/jssc.1998.7840
DO - 10.1006/jssc.1998.7840
M3 - Article
AN - SCOPUS:0039400165
VL - 139
SP - 266
EP - 273
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
SN - 0022-4596
IS - 2
ER -