PHASE COMPOSITION AND SURFACE STRUCTURE OF A PHOTOCATHODE BASED ON CeIr5 INTERMETALLIC COMPOUND

10.25712/ASTU.1811-1416.2023.03.009

Abstract

In this work, we studied the phase composition and structure of an Ir-16.7 at. % Ce alloy with CeIr₅ stoichiometry. Using X-ray phase analysis, it was found that the alloy is not single-phase, it contains three phases in significant amounts – CeIr₅, Ir and Ce₂Ir₇. The alloy has a polycrystalline structure; the grains consist of a highly dispersed eutectic mixture of two CeIr₅ + Ir phases. The CeIr₅ intermetallic compound forms a matrix in which        Ir crystals are included. Ir crystals are globular and needle-shaped. The characteristic size of globular crystals is       1-3 µm, the diameter of needle-like crystals is 0.5-1.0 µm. When the needle reaches the surface of the photocathode, Ir form a columnar structure with a radius of curvature of about 400 nm and a density of ρ = 33·10⁴ mm^-2. Dispersion of the structure provides a high density of interphase boundaries. The estimate shows that on a surface with an area of 1 mm², the length of the network of interphase boundaries is 0.83 m.