Dielectric relaxation of lanthanum doped zirconium oxide

Lanthanum doped zirconium oxide $(Lax–Zr1−xO2−δ)$ films, with La contents, up to $x=0.35$⁠, were studied. Films were annealed at $900°C$ to crystallize them into phases with higher $κ$-values. Increasing the La content suppressed the monoclinic phase and stabilized the tetragonal or cubic phase. The highest dielectric constant was obtained for a lightly doped film with a La content of $x=0.09$⁠, for which a $κ$-value of 40 was obtained. This was accompanied by a significant dielectric relaxation, following a single Curie–von Schweidler power-law dependency with frequency, changing to a mixed Curie–von Schweidler and Kohlrausch–Williams–Watts relationships after annealing. The dielectric relaxation was most severe for lightly doped films, which had the highest $κ$-values. The dielectric relaxation appears to be related to the size of crystal grains formed during annealing, which was dependent on the doping level.