 Erbium oxide nanoparticles also possess photoluminescence properties.Erbium oxide nanoparticles can be formed by applying ultrasound (20 kHz, 29 W·cm−2) in the presence of multiwall carbon nanotubes.The erbium oxide nanoparticles that have been successfully made by employing ultrasound are erbium carboxioxide, hexagonal and spherical geometry erbium oxide.