Abstract
The X-ray diffraction patterns of (Na 2/3Pb 1/3)(Mn 1/2Nb 1/2)O 3 ceramics were measured within 15–850 K temperature range. The anomaly in the thermal expansion temperature dependence occurred in 250–365 K range. The generalised Cole–Cole model was proposed to describe the measured effective electric permittivity influenced by high electric conduction and the coexistence of two contributions ɛ*( T, f) = ɛ* lattice + ɛ* carriers was considered. The analysis of the electric permittivity and conduction exhibited two relaxation processes. The electric conduction relaxation characteristic time values indicated the small polaron mechanism with τ 0 ≈ 10 −13 s occurring in 240–345 K range and the ionic mechanism with τ 0 ≈ 10 −11 s involved in the other relaxation occurring in the 320–510 K range. The ionic relaxation process was ascribed to a subsystem of defects, which was weakly interrelated to the anomaly in thermal expansion of the (Na 2/3Pb 1/3)(Mn 1/2Nb 1/2)O 3 ceramics. The Gate model was proposed to describe the ionic relaxation mechanism.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
