Conductivity of conductor

Conductivity of conductor

How to define a conductor? The very natural way to say that a conductor is a material that conducts electric current. But for a physicist, that's not enough, most materials do have a measurable conductivity, just the numbers vary by 20 order of magnitude. It is hard to draw the lines between conductors, semiconductors and insulators. However, some good examples (300 K) should be able to at least give us some idea.

Material	Conductivity Sm-1 or 1/(Ωm)	Ref
Silver	63.0 × 106
Copper	59.6 × 106
Gold	45.2 × 106
Mercury	1.0× 106
Carbon	2.8 × 104
Fe3O4	103
LuFe2O4	~1	[1] After breakdown 60V/cm-1
Germanium	2.2
LuFe2O4	10-2	[1] Before breakdown 10V/cm-1
Silicon	1.5× 10-3
BiFeO3	~1× 10-3	[2] 1kV/cm-1
Deionized water	5.5 × 10-6
Glass	10-10 -10-14
Paraffin	10-17
Teflon	10-22 - 10-24

Reference:
[1] Title: Nonlinear current-voltage behavior and electrically driven phase transition in charge-frustrated LuFe2O4
Author(s): Zeng LJ, Yang HX, Zhang Y, et al.
Source: EPL   Volume: 84   Issue: 5 Article Number: 57011   Published: DEC 2008

[2]Title: Switchable Ferroelectric Diode and Photovoltaic Effect in BiFeO3
Author(s): Choi T, Lee S, Choi YJ, et al.
Source: SCIENCE   Volume: 324   Issue: 5923   Pages: 63-66   Published: APR 3 2009