Electrical resistivity of magnetite and nickel ferrous ferrite above 300 Degrees K

The electrical resistivity of Fe sub 0.95 sup 2+ Fe sub 2.05 sup 3+ O sub 4 sup 2 minus, Ni sub 0.51 sup 2+ Fe sub 0.46 sup 2+ Fe sub 1.95 sup 3+ O sub 4 sup 2 minus, and Ni sub 0.89 sup 2+ Fe sub 0.13 sup 2+ Fe sub 2.11 sup 3+ O sub 4 sup 2 minus single crystals was determined at greater than 300 Degrees K. The dc resistivity less than or equal to 800 Degrees shows a monotonic decrease with increased temp., with an avg activation energy of 0.065 e V independent of temp. and Fe sup 2+ concentration. The ac resistivity, at frequencies of 540 kHz to 34 MHz less than or equal to 450 Degrees, shows temp. and frequency dependences of the relative dielectric constant similar to that found when true dielectric relaxation occurs, with the activation energy depending slightly on frequency and ferrous ion content. 32 refs.