Physica C-Superconductivity and Its Applications
Superconducting cuprate fluorides Nd0.7Sr1.3Cu(O,F)(4-delta) with T-c = 44 K were obtained by solid phase fluorination of the T-structure Nd0.7Sr1.3CuO4-gamma at low temperature (200-300 degrees C) using CuF2 as fluorinating reagent. The oxyfluoride has K2NiF4 structure with S.G. I4/mmm as its precursors, but the evident lattice expansions were observed. The a-axis expands from 3.7257(2) Angstrom to 3.9288(5) Angstrom and c-axis from 12.8240(3) Angstrom to 12.9630(2) Angstrom. No trace of SrF2 was detected in these fluorinated products. XRD and magnetic measurement revealed that the superconductivity in the fluorinated products originated from the oxyfluorides with reduced CuO2 plane and in the presence of the apical anion.
关键词:
hole concentration;copper;route;a=ca;tc
