Abstract
A superconducting KBi(2) sample was successfully prepared using a liquid ammonia (NH(3)) technique. The temperature dependence of the magnetic susceptibility (M/H) showed a superconducting transition temperature (T (c)) as high as 3.6 K. In addition, the shielding fraction at 2.0 K was evaluated to be 87%, i.e., a bulk superconductor was realized using the above method. The T (c) value was the same as that reported for the KBi(2) sample prepared using a high-temperature annealing method. An X-ray diffraction pattern measured based on the synchrotron X-ray radiation was analyzed using the Rietveld method, with a lattice constant, a, of 9.5010(1) Å under the space group of Fd3̄m (face-centered cubic, no. 227). The lattice constant and space group found for the KBi(2) sample using a liquid NH(3) technique were the same as those reported for KBi(2) through a high-temperature annealing method. Thus, the superconducting behavior and crystal structure of the KBi(2) sample obtained in this study are almost the same as those for the KBi(2) sample reported previously. Strictly speaking, the magnetic behavior of the superconductivity was different from that of a KBi(2) sample reported previously, i.e., the KBi(2) sample prepared using a liquid NH(3) technique was a type-II like superconductor, contrary to that prepared using a high-temperature annealing method, the reason for which is fully discussed. These results indicate that the liquid NH(3) technique is effective and simple for the preparation of a superconducting KBi(2). In addition, the topological nature of the superconductivity for KBi(2) was not confirmed.