Warm white emission of Ca₂P₂O₇: Dy³⁺, Eu³⁺ phosphor via hydrothermal method

Highlights: • Ca₂P₂O₇: Dy³⁺, Eu³⁺ phosphors were synthesized via the hydrothermal synthesis. • With the increase of pH value, the morphology of samples changed from spindles, tetragonal particles to long rods. • The best luminescence property of the sample is prepared at pH of 4 and a calcination temperature of 1000 °C. • With the calcination temperature increases, the phosphor morphology changed from long rods to tetragonal particles. • The chromaticity coordinate of Ca₂P₂O₇: 0.04Dy³⁺, 0.03Eu³⁺ phosphors was calculated to be (0.463, 0.340). -- Abstract: The Ca₂P₂O₇: Dy³⁺, Eu³⁺ phosphors were synthesized via hydrothermal method. The three-dimensional network structure of Ca₂P₂O₇ consisted of strong P-O covalent bond in [P₂O₇] and weak coupling between [P₂O₇] and Ca. The morphology was shown in detail by TEM and SEM images of precursors changed from spindles, tetragonal particles to long rods with the pH increased from 2 to 5. After sintering, the sample had the best luminescence property when pH was 4. The optimum sintering temperature was 1000 °C. The emission spectrum of Ca₂P₂O₇: Dy³⁺ was composed of three emission peaks. Based on the optimized doping concentration of Dy³⁺ was 0.04 mol, the doping of Eu³⁺ ions increased the red emission of the samples and finally samples obtained warm white emitting. The concentration quenching mechanism in the energy transfer from Dy³⁺ to Eu³⁺ was caused by dipole-dipole interaction. Ca₂P₂O₇: Dy³⁺, Eu³⁺ had excellent thermal stability. Thus, Ca₂P₂O₇: Dy³⁺, Eu³⁺ phosphor which could emit warm white light has fantastic potential applications for UV excited LED.