Characterization of binary Ce–Ir alloy photocathodes

Binary Ce-Ir alloys nominally containing 83, 78, 75, and 67 at% Ir were grown via arc melting in order to clarify the optimum composition for a Ce-Ir system to be used as photocathode material. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis were employed to characterize the microstructure and phase composition of these alloys. The results of the XRD analyses and SEM/EDX measurements indicated that single-phase homogeneous crystals composed of CeIr2 grains were successfully grown in the sample with an iridium content amounting to 67 at%. Through quantum efficiency (QE) measurements, it was revealed that the QE of the Ce-67 at% Ir alloy (CeIr2 phase) is a few times higher than that of the other Ce-Ir alloys. (C) 2019 The Japan Society of Applied Physics