Photoluminescent and thermal properties of (Sr0.995−x−y−zCaxBayMgz)2SiO4:0.01Eu2+ phosphors for warm white light-emitting diodes

• The photoluminescent property of Sr2SiO4:Eu2+ is improved by doping Ca2+ and Ba2+.
• The emission spectra red-shift obviously by doping Ca2+ into Sr2SiO4:Eu2+.
• The thermal stability is enhanced by doping Ba2+ into (Sr,Ca)2SiO4:Eu2+.
• The improved phosphors can combine blue-LED chips to generate warm white light.

A series of phosphors (Sr0.995−x−y−zCaxBayMgz)2SiO4:0.01Eu2+ (0 ≤ x ≤ 0.45, 0 ≤ y ≤ 0.015, 0 ≤ z ≤ 0.35) were synthesized by solid state reaction. Their phase compositions and photoluminescent properties were investigated in detail. The X-ray diffraction analysis indicates the impurity phase of SrSiO3 is formed only when z ≥ 0.25. A photoluminescence investigation shows, with x increasing the emission spectra of the phosphors (0 ≤ x ≤ 0.45, 0 ≤ y ≤ 0.015, z = 0) obviously red-shift, the corresponding color tones shift from yellow to orange–yellow and their CCTs reduce from 2875 to 2237 K. All the results are beneficial for the phosphors to combining blue light-emitting diode chips to generate warm white light. Besides, the thermal stability of the phosphor (x = 0.36, y = z = 0) is enhanced by doping Ba2+, due to the greater activation energy for the compounds containing barium.

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