Electrical Conductivity. The electrical conductivity of these pellets was measured using a Jandel Model RM3000+ and four-point probe rig, with 1 mm spacing between probes. A 100 mA current (𝐼) was applied between the outer probes, and the voltage drop (Δ𝑉) read between the inner probes. The conductivity (𝜎) was found using: