Comparison of charging phenomena under electron beam of m-ZrO2 and yttria stabilized zirconia

Abstract

This article presents a study performed with a dedicated scanning electron microscope on the electrical property evolution of monoclinic ZrO₂ (m-ZrO₂) and yttria-stabilized zirconia (YSZ). The charging behavior is studied during the charge injection process at 1 keV, by measuring the secondary electron emission σ. The physical properties of zirconia change are shown under the dopant effect. In fact, for YSZ, the substituting cation Y³⁺ has a lower valence than that of the initial cation Zr⁴⁺, so oxygen vacancies are created to maintain the neutrality. These vacancies promote the relaxation of created charges within YSZ. For this reason, we distinguish between the conductive behavior of YSZ and trapping behavior of m‑ZrO₂. The new conductive behavior of YSZ is clearly visible in the variation of the charge generated as a function of the injected dose. Indeed, for m‑ZrO₂, the generated charge tends towards a constant, independent of the dose, while for YSZ, it varies linearly as a function of it. This proves that the probability of charges, successive jumps from one oxygen vacancy to another, increases and, subsequently, the mobility becomes sufficiently high to generate a current within YSZ and an expansion of the injected charge.