Preparation and up-conversion luminescence characteristics studies of K3YF6: Ho3+, Yb3+ with cryolite structure

Highlights: • Single-phase up-conversion luminescent materials K₃YF₆: Ho³⁺,Yb³⁺ with cryolite structure were obtained for the first time. • The up-conversion luminescence properties and mechanism of the as-prepared samples were analyzed under excitation of 980 nm. • Two-phonon up-conversion phenomenon was confirmed. Cryolite was considered to be an ideal up-conversion host material due to its low phonon energy, which can effectively suppress the radiation-free transition process of excited state energy levels. In the present paper, a novel up-conversion material K₃YF₆:Ho³⁺, Yb³⁺ with cryolite structure was prepared successfully using a high-temperature solid state method. The up-conversion luminescence properties of K₃YF₆ doped with different Ho³⁺/Yb³⁺ doping ratio were investigated and the optimal doping ratio were confirmed in this system. Under 980 nm excitation, Ho³⁺/Yb³⁺ co-doped K₃YF₆ revealed a strong green emission at the 541 nm, 549 nm and a weak red emission peaking at 666 nm, corresponding to the ⁵F₄, ⁵S₂→⁵I₈ and ⁵F₅→⁵I₈ transitions of Ho³⁺, respectively. All the red and green up-conversion emission of K₃YF₆:Ho³⁺, Yb³⁺ belong to two-photon process and energy transfer from Yb³⁺ to Ho³⁺ simultaneously. Additionally, to understand the energy transfer and electronic transition process of the red and green light emitted, the possible luminescence mechanism were also analyzed in this paper. All the results indicate that Ho³⁺/Yb³⁺ co-doped K₃YF₆ have potential application value in green up-conversion luminescent materials.