Color tunable warm white emitting whitlockite-type phosphor applied in optical thermometry

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 Dy 3+ singly doping and Dy 3+ , Eu 3+ 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 Dy 3+ and Eu 3+ 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 : Dy 3+ , Eu 3+ phosphors increase with the Eu 3+ concentration rises, changing from cold white light to warm white light. The integrated emission intensity of Dy 3+ in the phosphor decreases with the change in the doping ratio of Dy 3+ and Eu 3+ , causing by the energy transfer from Dy 3+ to Eu 3+ . The Ca 2·6 K 0·2 La 0·13 (PO 4 ) 2 :0.06Dy 3+ , 0.01Eu 3+ 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 : Dy 3+ , Eu 3+ phosphors can be applied to w-LEDs and display devices, and can be used as a new type of optical thermometer.