Φ and Ψ show the arbitrary UCL of cubic and hexagonal cores, respectively, and the enhancement factors as their multiples are measured for shell structures.

Structure of particle	UCL enhancement factor
α-NaYF4:Yb,Er	1Φ
α-NaYF4:Yb,Er@α-NaYF4	5Φ
α-NaYF4:Yb,Er@β-NaYF4	22Φ
β-NaYF4:Yb,Er	1Ψ
β-NaYF4:Yb,Er@α-NaYF4	5Ψ
β-NaYF4:Yb,Er@β-NaYF4	6Ψ