Cathodoluminescence Microscopy and Secondary Electron Emission in Mechanically Polished and Electron Irradiated YBa2Cu3O7−x Ceramics

Abstract

Cathodoluminescence (CL) and secondary electron emission (SEE) in the scanning electron microscope have been used to study the effects of mechanical polishing and electron irradiation on YBa2Cu3O7‐x ceramics. CL spectra from the mechanically polished superconductors show an enhanced 2.4 eV luminescence band, which is related to oxygen content redistribution or depletion. Electron irradiation induces strong morphological and compositional changes which are proposed to be connected with melting‐resolidification processes and surface phase segregation. SEE yield measurements allow to detect an oxygen depleted area with stoichiometric cationic composition surrounding the irradiated region. CL spectra recorded from this oxygen‐deficient area also show an enhanced 2.3 to 2.4 eV emission band in comparison with the spectra recorded from the non‐irradiated material. Strongly luminescent non‐superconducting phases appear in the irradiated regions, showing intense 3.1 and 0·78 to 0·81 eV emission bands.

Electron beam induced compositional and structural changes in

“…Our observations support the relation between the 540 nm luminescence band and oxygen depletion, as confirmed by the SEE yield measurements of oxygen deficiency around the irradiated area. These results agree with previous investigations in electron irradiated YBCO ceramics [23]. In [23] thermally driven diffusion processes were proposed as the mechanism leading to the creation of the oxygen depleted area surrounding the irradiated region.…”

“…These results agree with previous investigations in electron irradiated YBCO ceramics [23]. In [23] thermally driven diffusion processes were proposed as the mechanism leading to the creation of the oxygen depleted area surrounding the irradiated region.…”

“…In the electron irradiated area an increase of the SEE yield has been observed. effect was also found in irradiated YBCO [23], and can be explained as a result of the electron irradiation induced changes in the cationic composition and oxygen losses [17]. According to the results summarized in figures 11-13, the increase of the SEE yield could be partially due to the reduction of oxygen content during irradiation.…”

Effects of specimen preparation on the cathodoluminescence properties of ZnO nanoparticles

“…The decrease of the UV intensity during electron beam irradiation may be related to the surface modifications, such as adsorption/desorption or electron-simulated surface reaction. [18][19][20][21][22] Compared with high density and bulk crystal, the exposed surface and surface-tovolume ratio are larger for low density, which induces a quicker and more serious drop during irradiation. In the following, the spectra are taken after stabilization of the intensity in order to prevent the effects of the surface modification during the measurements.…”