Electrical conductivity of Li-Ti ferrites

Both, de and ac conductivities of the Li-Ti ferrite system with chemical formula Li0.5+0.5xTizFe2.5-1.5xO4 for 0 less than or equal to x less than or equal to 0.7 were measured at room temperature and elevated temperatures up to 833 Ii. The ac conductivity was measured in the frequency range from 100 Hz to 100 kHz. A strange behavior was observed and two regions appear in the conductivity-temperature dependence. The low-temperature range, region I, was attributed to impurity conduction in addition to an effective carrier-phonon interaction. A hopping conduction mechanism was considered for the conduction in region II. The hopping threshold energy corresponding to T-m, the temperature at which a minimum in conductivity occurs, was determined. The hopping energy Delta w), the exponential frequency parameter (S) and the phonon frequency (v(p)) were estimated.