Internal Friction, Dielectric Loss, and Ionic Conductivity of Tetragonal ZrO ₂ ‐3% Y ₂ O ₃ (Y‐TZP)

The defect structure in 3 mol% Y‐TZP was studied by correlated internal friction, dielectric loss, and ionic conductivity experiments. A prominent mechanical and dielectric loss peak occurs in the temperature range between 380 and 550 K that depends on the frequency of measurement. The relaxation parameters were determined as H m = 90 ± 3 kJ·mol −1 , τ ∞ = (1.0 +1.5 −0.6 ) × 10 −14 s for the mechanical relaxation and H d = 84 ± 3 kJ·mol −1 , τ ∞ = (1.6 +1.7 −0.9 ) × 10 –13 s for the dielectric relaxation. The ionic conductivity below 790 K is controlled by an activation enthalpy of H σ = 89 ± 3 kJ·mol −1 ; at higher temperatures H σ = 60 ± 3 kJ·mol –1 . An atomistic model is presented which assumes that oxygen vacancies are trapped by yttrium ions forming anisotropic complexes which—by reorientation—cause anelastic and dielectric relaxation. At higher temperatures (>790 K) these complexes are dissociated, which leads to the reduced activation enthalpy for ionic conductivity.