Variable range hopping conductivity in Y123–Y211 composites close to the percolation limit

The normal state resistivity of the Y₁₂₃–Y₂₁₁ percolation system is best represented by a variable range hopping (VRH) model in which the electronic states of the system are localized. The characteristic temperature T₀, in the VRH representation ρ=ρ₀(T₀/T)¼ has been used to deduce the hopping length (α⁻¹) and we find that as the percolation limit is approached α⁻¹ decreases