Abstract
Room temperature ferromagnetism of GaN powder with vacancies was realized by the mechanical milling method, where the GaN powder was milled by WC balls at 0～700 rpm for 15 minutes. The grain size of GaN powder was reduced to below 10 nm by the milling above 200 rpm. The crystal structure of milled powder kept a wurtzite-type hexagonal one. Enhancement of magnetization M at 200 rpm is considered to be due to the formation of vacancies. On the other hand, the rapid increase of M at 600 rpm corresponded to the discontinuity expansion of lattice parameter a by the overproduction of vacancies.
