Electrical Conductivities and Defect Structures of Pure NiO and Chromium-Doped NiO

The electrical conductivities of "pure" nickel oxide (NiO) and nickel oxide doped with chromium (Cr) have been measured over a temperature range from 700—1200° C and an oxygen partial pressure range from the equilibrium pressure for Ni/NiO coexistence to 1.0 atmosphere. The positive hole conductivity of the purest available NiO was found to be proportional to P0'* at temperatures greater than 850 °C which indicates that the predominant ionic defects in NiO are fully ionized cation vacancies. The positive hole conductivity of CV-doped NiO was proportional to PJ/4. This pressure dependence is expected if Cr3+ dopant ions