Coupled fast and slow relaxation dynamics in ion conduction g solids

The observations of slow relaxation process within a wide range of timescales larger than microscopic vibrational times are well established in the motion of charged defects in ionic and electronic solids. A complex relaxation time function φ*(t)=exp(-(t/τ)Γ*) is proposed, where Γ*=(iτ)^1-g, the relaxation time τ (referred as fast relaxation time) and Γ* delays the fast relaxation time τ to τ^g (referred as slow relaxation time), g is an exponent 0<g≤1 and i=√-1. The Γ* is playing a key role and it couples fast and slow relaxation dynamics processes. The physical picture for the Γ* is envisioned in terms of trapping and correlation of mobile hopping charge polarization in the disordered host lattice. Ac conductivity in ion conducting solids is interpreted by considering fast and slow scales of relaxation dynamics of charge carriers. (author)