A facile neoteric technique to achieve [SrF2:Eu3+@SiO2]//[SrF2:Tb3+@SiO2] Janus yolk–shell nanofibers with ideal white-light emission via triple-inhibiting energy transfer between Tb3+ and Eu3+ ions

[SrF 2 :Eu 3+ @SiO 2 ]//[SrF 2 :Tb 3+ @SiO 2 ] Janus yolk–shell nanofibers (JYSNFs) are innovatively designed and conveniently constructed to fully avoid energy transfer between Tb 3+ and Eu 3+ .