Electrophysical properties of BT-30 ceramics

Abstract

The article studies the electrophysical characteristics of (BeO + TiO₂)-ceramics modified with TiO₂ micro- and nanoparticles in an amount of 30 wt. % (BT-30) by measuring the total complex resistance (impedance). The dispersion of the real ε’ and imaginary components of the dielectric constant ε” and specific conductivity in the frequency range from 100 Hz to 100 MHz and temperatures from room temperature to the boiling point of liquid nitrogen was determined. Large values of ε’ and ε” in the low-frequency region are characteristic of structurally inhomogeneous materials due to the accumulation of electric charges on the surface and inside microcrystals. Two dielectric relaxation processes associated with electrical conductivity in the bulk and on the surface of ceramics were first discovered. An increase in conductivity with an increase in the microwave field frequency above 1 MHz is explained by the appearance of a relaxation component of the current. The activation energy of the static resistance of ceramic samples was determined as a function of the reciprocal temperature, which depends little on the mass content of TiO₂ nanoparticles and varies in the range of 0,024‒0,10 eV. This also confirms the existence of two independent conduction processes, weakly dependent on the content of nanoparticles in the composition of ceramics. When such ceramics are placed in a high-frequency electric field, spatial charges are formed, the field of which contributes to the creation of additional polarization and dielectric losses.