superconducting transition
A transition at the critical temperature, \(T_{\text{c}}\), below which the resistance of electrical conductors becomes zero and magnetic flux is excluded. Examples: The transitions of Nb3Sn, Nb3Al and V3Si to superconductors (\(15\ \text{K} < T_{\text{c}} < 20\ \text{K}\)) and YBa2Cu3O7-x (\(x\approx 0.2\)) at \(90\ \text{K}\).
PAC, 1994, 66, 577. 'Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)' on page 592 (