Electron holographic studies of irradiation damage in BaTiO₃

Abstract

Using an electron holographic technique, we investigated the charging-up phenomena of BaTiO3 particles under electron beam irradiation. BaTiO3 particles were confirmed to be charged up by electron irradiation just after insertion in a transmission electron microscope (TEM). However, the amount of the electric charge induced by electron irradiation was found to decrease by further irradiation in a TEM. After irradiating for 1.5 h, about half of the electrical charge was lost compared with that in the initial state. This implies that the electric resistivity of the particle decreased upon irradiation. In addition, this reduction process of the resistivity due to irradiation was confirmed to be an irreversible reaction. It could be concluded that the reduction of resistivity is attributed to the generation of oxygen vacancies due to the irradiation. The electron irradiation technique can be considered to be a new modification method of conductivity in BaTiO3-based materials.

Electron beam damage in oxides: a review

“…It has been confirmed by electron holographic technique that BaTiO 3 particles can be charged up by electron irradiation right after the sample is exposed to the electron beam [198]. Most interestingly, the amount of induced electric charge decreases with increasing electron irradiation.…”

In situformation of bismuth nanoparticles through electron-beam irradiation in a transmission electron microscope

“…As the new nanostructures have been mainly studied by transmission electron microscopy, important research into electron irradiation effects on the nanostructures has been conducted using novel in situ characterization techniques. Yamamoto et al [13], reported the modification of the conductivity in an insulating BaTiO 3 using electron holographic studies of irradiated sample in a transmission electron microscope (TEM). The stability and the crystallization of amorphous alloys by electron irradiation have also been studied in situ [14].…”

Structural Instability in Electrically Stressed, Oxygen Deficient BaTiO3 Nanocrystals

“…[24] Without ion beam milling, the surface of annealed BaTiO 3 nanocrystals prepared in the current work stays highly resistant and electrostatic charging can be significant. [28] While both elastic and inelastic electron-atom interactions may participate in the amorphization process by generating oxygen vacancies within the nanocrystal, the following features are better explained in terms of oxygen vacancy migration under the e-beam induced electric field. i) The region subject to electrostatic charging can be larger than the e-beam illuminated area by means of ion migrations, resulting in a larger amorphized area within a BaTiO 3 nanocrystal than the e-beam illuminated area when exposed to high dose rates as shown in Figures 1 and 4. ii) The migration of oxygen vacancies is a dynamic process and local oxygen vacancy content can vary with time, so a reversible crystalline/amorphous transition can exist in the illuminated region as noticed in Figure 6. iii) The electric field direction is radial and consistent with the outward growth direction of the amorphized region shown in Figure 6c.…”

“…Without ion beam milling, the surface of annealed BaTiO 3 nanocrystals prepared in the current work stays highly resistant and electrostatic charging can be significant. [ 28 ] While both elastic and inelastic electron‐atom interactions may participate in the amorphization process by generating oxygen vacancies within the nanocrystal, the following features are better explained in terms of oxygen vacancy migration under the e‐beam induced electric field. i) The region subject to electrostatic charging can be larger than the e‐beam illuminated area by means of ion migrations, resulting in a larger amorphized area within a BaTiO 3 nanocrystal than the e‐beam illuminated area when exposed to high dose rates as shown in Figures 1 and 4.…”