ISSN:
1077-3118
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Using an unconventional reduction method, high-pressure sintering at 6.0 GPa and about 600 °C for 20 min, we have produced high-quality n-type Ln1.85Ce0.15CuO4−y (Ln=Pr, Sm, and Eu) superconductors from the as-prepared materials. The samples show higher critical temperatures, higher superconducting phase fractions, and much lower resistances in the normal state than those synthesized by conventional methods. The increase of critical temperature in Eu1.85Ce0.15CuO4−y is most obvious with an onset temperature Tonc and zero-resistance temperature Tc0 of 28.4 and 23.3 K, respectively. High-pressure sintering seems to be effective on the modulation of the fine crystal and electronic structures of n-type systems. In particular, metallic resistance versus temperature behaviors in normal states similar to those found in single crystals and epitaxial films are observed in Sm1.85Ce0.15CuO4−y and Eu1.85Ce0.15CuO4−y, in sharp contrast to the semiconductorlike behaviors in the conventionally prepared samples. From transmission electron microscopy studies, it is found that the compacting and regrowth of the polycrystal under high-pressure sintering greatly improves the weak links at grain boundaries.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.109131
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