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Whitlockite-type structure phosphors have received extensive attention and research due to their adjustable chemical compositions in isomorphic compounds and providing rich crystal positions for doping activators. Ca 2.6 K 0.2 La 0.2 (PO 4) 2 whitlockite-type phosphors with Dy3+ singly doping and Dy3+, Eu3+ co-doping were prepared via high temperature solid-phase reaction, and the crystallographic characteristics, luminescence properties and temperature sensing performance were investigated in detail. The prepared phosphors are pure phase and both Dy3+ and Eu3+ enter into the matrix and produce blue, yellow and red emissions. The CCT values of the emitted light from Ca 2·6 K 0·2 La 0·2 (PO 4) 2 : Dy3+, Eu3+ phosphors increase with the Eu3+ concentration rises, changing from cold white light to warm white light. The integrated emission intensity of Dy3+ in the phosphor decreases with the change in the doping ratio of Dy3+ and Eu3+, causing by the energy transfer from Dy3+ to Eu3+. The Ca 2·6 K 0·2 La 0·13 (PO 4) 2 :0.06Dy3+, 0.01Eu3+ phosphor shows temperature sensing performance based on FIR technique, with the maximum relative sensitivity calculated to be 0.181% K−1. All the results reveal that the Ca 2·6 K 0·2 La 0·2 (PO 4) 2 : Dy3+, Eu3+ phosphors can be applied to w-LEDs and display devices, and can be used as a new type of optical thermometer. Dy3+/Eu3+ co-doped Ca 2·6 K 0·2 La 0·2 (PO 4) 2 phosphor applied for w-LEDS and temperature sensing. [Display omitted] • Single-phase luminescent materials Dy3+, Eu3+ co-doped Ca 2·6 K 0·2 La 0·2 (PO 4) 2 phosphor with whitlockite structure was synthesized for the first time. • The concentration quenching and energy transfer mechanisms were investigated. • The emission color of Ca 2·6 K 0·2 La 0·2 (PO 4) 2 : Dy3+, Eu3+phosphors changes from natural white light to warm white light with the increase of Eu3+ concentration. • The samples showed temperature sensing performance with maximum S a to be 2.06 × 10−3 K−1 and S r to be 0.181% K−1 under 303 K. [ABSTRACT FROM AUTHOR]

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 K 3 YF 6 :Ho3+, Yb3+ with cryolite structure was prepared successfully using a high-temperature solid state method. The up-conversion luminescence properties of K 3 YF 6 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 K 3 YF 6 revealed a strong green emission at the 541 nm, 549 nm and a weak red emission peaking at 666 nm, corresponding to the 5F 4 , 5S 2 →5I 8 and 5F 5 →5I 8 transitions of Ho3+, respectively. All the red and green up-conversion emission of K 3 YF 6 :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 K 3 YF 6 have potential application value in green up-conversion luminescent materials. • Single-phase up-conversion luminescent materials K 3 YF 6 : 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. [ABSTRACT FROM AUTHOR]