Facile synthesis and multicolor luminescent properties of uniform Lu2O3:Ln (Ln = Eu3+, Tb3+, Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+) nanospheres

► A facile precipitation method was used to prepare uniform Lu2O3:Ln nanospheres. ► The samples exhibit multicolor down-conversion and up-conversion luminescence. ► The possible formation mechanism was well investigated. ► The color of the phosphors was tuned by doping different rare earth ions.