Strain-Induced Enhancement of Eu 3+ Emission in Red Phosphor NaMgPO 4 :Eu 3+ , Al 3+

series of (NaMgPO 4 ) 0.98− x : Eu_0.02^3 + , Al_x^3 + phosphors were prepared by the solid-state method. X-ray powder diffraction results confirm that the samples contain mixture phases of crystals. The doped effect of Al 3+ on the photoluminescence properties of (NaMgPO 4 ) 0.98− x : Eu_0.02^3 + , Al_x^3 + phosphors is discussed. The results indicate that two dependent curves of emission relative intensity and strain on Al 3+ doping concentration are all Gaussian curves, and a high correlation is observed between emission relative intensity of Eu 3+ and strain caused by Al 3+ . In other words, emission relative intensity of Eu 3+ is enhanced with the increase of the strain. The enhanced mechanism of the strain is discussed. In addition, (NaMgPO 4 ) 0.98− x : Eu_0.02^3 + , Al_x^3 + phosphors are electric dipole-dominated transition red phosphors. The optimal molar concentration of Al 3+ for the samples is 9