Ce3+ and Pr3+ ions co-doping Cu2+ ions EPR spectroscopy Eu3+ and Sr2+ ion co-doping EuS History of engineering & technology SmS Technology: general issues antimicrobial activity antimicrobial effect apatite bone augmentation brackets calcium hydroxyapatite nanopowders cooper ions dental implants dental nanomaterials diphosphates endodontics europium ions hydroxyapatite interdiffusion lanthanides luminescence microorganisms microwave-assisted hydrothermal method nanocomposites nanocrystallites nanohydroxyapatite nanomaterials