Electric relaxation in Nb₆VSb₃O₂₅-ceramics

Broadband dielectric spectroscopy measurements of Nb₆VSb₃O₂₅ showed that in both the real (ε') and imaginary (ε'') components of permittivity there is visible relaxation process strongly obscured by dc conductivity. Application of the electric modulus representation of the data enables to study temperature evolution of this relaxation together with conductivity relaxation. It was showed that the activation energies for both processes are close. Low-frequency loss tangent increases strongly with temperature, suggesting that in the compound under study additional energy losses are associated with the conduction of electric current, as determined by the Joule-Lenz law.