Morphology control of the NaGdF4:Yb,Tm@NaGdF4 core–shell nanostructure by tailoring the ratio of core to shell

A method was developed to control the morphology of the NaGdF₄:Yb³⁺,Tm³⁺@NaGdF₄ core–shell nanostructure by tailoring the ratio of precursors in the core and shell forming process.