Dielectric Properties of Lithium–Titanium Ferrite Ceramics

The temperature dependences of the real and imaginary parts of the complex dielectric permittivities of ceramic Li–Ti ferrospinel are measured within the frequency range 102–106 Hz. The empirical expressions describing these dependences are derived and the frequency-independent electrophysical parameters of the material under study are obtained. The best agreement between the experimental and calculation data is achieved when the time constant and the static dielectric permittivity are decreasing functions of frequency. A model of relaxational processes accounting for this result is proposed. A certain role in polarization of the relaxation agents, whose reorientation is controlled by tunneling electron transitions inside the “two-valence iron ion – three-valence metal ion”, is assumed. It is stated that under certain conditions, the relaxation agent reorientation is likely to possess a collective character. The temperature dependences ε′ and ε″ are derived for a number of dc currents at different electric field strengths. Sharp variations in the dielectric characteristics of the ceramics are found.