Characterization of functional materials for liquid blanket systems by cathodoluminescence measurement

Applicability of cathodouminescence (CL) measurements in development of functional materials for advanced liquid blanket systems was investigated by using a conventional scanning microprobe and CCD spectrometer. Firstly, CL spectra of lithium compounds for tritium fuel breeding, oxide, nitride and carbide functional materials for advanced blanket systems, fluoride materials for coolants, etc. were obtained to construct a database. Relations between changes in the spectra and the crystallinities of specimens were examined for ZrO2, Y2O3 and TiO2 coatings baked at different temperatures. The specimens with lower crystallinities showed broader luminescence peak at longer wavelengths. Changes in CL spectra by irradiation damages were also examined for Y2O3 and SiC by ion beam irradiations. Since luminescence intensity decreased significantly for the specimens with low crystallinities, an SEM system which can control the electron beam current more than 2 orders while keeping the spatial resolution of <1 μm is suitable for quick acquisition of CL spectra in the development of the functional materials. Once a database of CL spectra for candidate materials and their changes by crystallinities and irradiation damages is constructed, the CL measurement would be a reliable tool also in inspection and monitoring of materials during reactor construction and operation.