Abstract: α-Al₂O₃ with different orientations were implanted with CuCl⁺ ions,then annealed in reducing atmosphere at different temperature.These samples were analyzed under SEM.It is found that sub-μm particles appeared on the surface of the samples.The defects produced by ion implantation segregate during annealing process,where single color centre combining with CuCl⁺ ion forms defect complex leading to the segregation of CuCl⁺ ions.With prolongation of annealing time,the degree of segregation becomes high resulting in the formation of sub-μm particles.The size and distribution of these particles depends on ion implantation conditions and annealing temperature.