Conventional superconductors are materials that display superconductivity as described by BCS theory or its extensions.
Critical temperatures of some simple metals:
ElementTc (Kelvin) Aluminum (Al)1.20 Mercury (Hg)4.15 Molybdenum (Mo)0.92 Niobium (Nb)9.26 Lead (Pb)7.19 Tantalum (Ta)4.48 Titanium (Ti)0.39 Vanadium (V)5.30 Zinc (Zn)0.88
Niobium and vanadium are type-II superconductors, while most other superconducting elements are type-I materials. Almost all compound and alloy superconductors are type-II materials.
The most commonly used conventional superconductor in applications is a niobium-titanium alloy - this is a type-II superconductor with a Tc of 11 K. The highest critical temperature so far achieved in a conventional superconductor was 39 K (-234 °C in magnesium diboride.