Superconducting properties of Nd<sub>1+x</sub>Ba<sub>2-x</sub>Cu<sub>3</sub>O<sub>y</sub> single crystals isothermally grown at various temperatures
Takamitsu Higuchi; Koichiro Waki; Goro Osabe; Sang-Im Yoo; Masato Murakami
Журнал:
Superconductor Science and Technology
Дата:
2000-06-01
Аннотация:
Nd<sub>1+x</sub>Ba<sub>2-x</sub>Cu<sub>3</sub>O<sub>y</sub> (Nd123ss) single crystals were isothermally grown under controlled oxygen partial pressure of 1% O<sub>2</sub> at various growth temperatures (T<sub>g</sub>) from 1000 to 1020 °C with a flux method. The flux composition of 20 mol% NdBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> (Nd123) and 80 mol% Ba<sub>3</sub>Cu<sub>5</sub>O<sub>8</sub> (035) was employed. Nd123ss single crystals grown at T<sub>g</sub>≥1010 °C exhibited a transition temperature T<sub>c</sub>≈95 K with transition width ≈1 K, the peak field (B<sub>pk</sub>)≈2-3 T and the irreversibility field (B<sub>irr</sub>) at 77 K much higher than the experimental limit of 7 T. As the growth temperature is lowered, both the B<sub>pk</sub> and B<sub>irr</sub> were reduced, which can be explained in terms of the chemical fluctuation which can occur at lower T<sub>g</sub>.
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