Dielectric properties of single crystal Co/MgO

The dielectric constants of single crystal MgO doped with cobalt have been measured at room temperature from 500 Hz to 15 KHz. The cobalt concentrations varied from 310 to 9900 ppm. For all specimens the a.c. conductivity fitted well to the relation σ ∝ ωⁿ with n = 0.90 ± 0.10. In contrast to the behaviour of single crystal MgO doped with trivalent iron or chromium, previously reported 1], the addition of divalent cobalt does not appear to increase the conductivity in the frequency range examined.