SYNTHESIS AND SUPERCONDUCTING PROPERTIES OF FLUORINATED LA2CUO4 USINGNH4F

Superconducting La2CuO4-deltaFy samples were synthesized by heating La 2CuO4 together with a fluorinating reagent, NH4F, at 240 degrees C in flowing oxygen gas. Bulk superconductivity with T-c = 42 K in the samp les was confirmed by DC magnetic susceptibility measurements. The enha ncement in the orthorhombicity of the K(2)NIF5 phase (a = 5.319 Angstr om, b = 5.442 Angstrom, c = 13.20 Angstrom) was observed. The lower an d upper critical fields, H-c1(0) and H-c2(0), for the La2CuO4-deltaFy were roughly determined to be 98 Oe and 600 kOe, respectively. (C) 199 7 Elsevier Science B.V.