Relaxation of Electric Conduction in Pb(Mn_1/3Nb_2/3)O₃ Ceramics: Subsystem of Defects Behavior Under Pressure

Abstract

Electric conductivity relaxation times τ were obtained from impedance measurements of Pb(Mn _1/3 Nb _2/3 )O ₃ ceramics. Two relaxation processes were discerned with use of derivative ∂ ε ′ /∂ (logf) and electric modulus M” approaches. The applied axial pressure X decreases the relaxation times above threshold pressure X _thresh ≈ 50 MPa. In case of a hydrostatic pressure, the rate of ∂ τ /∂ p changes at p _cr ≈ 0.9 GPa. The pressure effects and bi-vacancies role are described in framework of the Gate Model.

Keywords:

• Relaxation times
• hydrostatic pressure
• axial pressure
• Pb(Mn,Nb)O₃