Sharp Superconductivity Transition at 94 K in HoBa₂Cu₃O7-δ and ErBa₂Cu₃O7-δ

We report the results of temperature dependences of the resistivity and the magnetic susceptibility in (a) HoBa 2 Cu 3 O 7-δ and (b) ErBa 2 Cu 3 O 7-δ whose structure and phase are confirmed by Rietveld analysis of X-ray powder diffraction. (a)- and (b)-compounds show a very sharp superconductivity transition at 94 K with the transition width of 1.0 K and 1.4 K, respectively, strongly suggesting that these samples consist of a single-phase superconductor. According to a simultaneous investigation of the structural properties on the same samples, it is strongly suggested that the orthorhombic phase is the superconducting phase at 94K both in (a)- and (b)-compounds, which is proposed recently as a dominant polymorphs of YBa 2 Cu 3 O 7-δ .