Dielectric, impedance, modulus and conductivity
studies were performed over temperature 35 °C–600 °C and
frequency 45 Hz–5 MHz range on the Lead Potassium Lithium Niobate
(Pb4.0K1.0Li1.0Nb10O30, PKLN) ceramics. These
studies established the conduction ion motion and polarization mechanism in
the material. The dispersive dielectric loss at high temperature reveals the
ionic conductivity. From frequency variation of εl response
the pre-factor A(T) and critical exponent n(T) are evaluated, and are used
in Jonscher's dielectric dispersion relation for ε' to fit with
the experimental data. Complex impedance plots showed a non – Debye type
relaxation, are used to evaluate the grain and grain boundary conduction and
relaxation activation energies. DC and ac conduction activation energies are
estimated from Arrhenius plots. Occupancy of Li+ for C-sites gave
a completely filled structure and enhanced the phase transition temperature
to 520 °C compared to PKN. This is supported by the conduction
activation energy in ferro region is more than the para region. Also, the dc
conductivity characterized from bulk resistance and Mll peak frequency.
Polaron hoping mechanism at room temperature has been confirmed via the
linear variation of the plot log (σac – σdc) as a
function of log ω2. Stretched exponential parameter, β
(0 < β$\leqslant$ 1) has been evaluated from impedance plots, interpreted as
a result of correlated motions between the Li+ ions and distribution of
dielectric relaxation. Compared the results from different techniques, and
discussed the conduction mechanism in the material.