ELECTRICAL-CONDUCTIVITY AND SUPERCONDUCTIVITY OF ZRNI4P2 AND ZRRU4P2 PREPARED AT HIGH-PRESSURE

Ternary metal phosphides ZrNi4P2, ZrRu4P2 and HfRu4P2 have been prepar ed at high temperatures and high pressures. The X-ray diffraction line s of these compounds are assigned by;the index of the ZrFe4Si2-type st ructure. The resistivity of ZTNi(4)P(2) decreases rapidly with decreas ing temperature. It behaves as a metal. The relation between the elect rical properties and the structure in ZrNi4P2 is discussed. The superc onductivity in ZrRu4P2 and HfRu4P2 is found at around 11 K and 9.5 K, respectively. These are new superconductors. The T-c of 11 K in ZrRu4P 2 is the highest value obtained during various sample preparations and annealing conditions. The upper critical held (H-c2) obtained from H- c2 vs temperature curve for ZTRu(4)P(2) is 12.2 tesla at 0 K when the midpoint of the resistivity jump is taken as the T-c. The superconduct ivity of ZrRu4P2 and HfRu4P2 is discussed. (C) 1997 Elsevier Science L td.