Blue-luminescent hafnia nanoclusters synthesized by plasma gas-phase method

We report the preparation of a blue luminescent metal oxide, hafnia nanoclusters (NCs), via plasma gas-phase condensation deposition method. The as-synthesized hafnia NCs show a narrow size distribution with a mean cluster size of d = 6.5 nm and possess a tetragonal crystal structure that was rarely obtained at room temperature via traditional synthetic methods. The as-prepared hafnia NCs are surface clean and have high purity because of vapor condensation and cluster growth in the high vacuum and dry system. It is suggested that the blue luminescence should originate from oxygen defects in the tetragonal hafnia NCs.