Photoluminescence properties and thermal stability of Eu3+-activated La7Ta3W4O30 red-emitting phosphors for near-UV-excited w-LEDs

Novel trivalent europium(Eu)-activated LaTaWO:xEu(x=0.5 mol%-40 mol%) red-emitting phosphors were synthesized by means of a high-temperature solid-state reaction.The structure,morphology,photoluminescence,thermal-stability properties,lifetime,and color-rendering of the prepared phosphors were investigated in detail.The LaTaWO:Euphosphors show five emission peaks under near-ultraviolet(n-UV) at 397 nm,and these peaks are ascribed to the transitions of ~5 D-~7 F(j=0,1,2,3 and 4) by Euions.The optimal doping concentration of Euis 20 mol%,and the critical distance of the energy transfer between the Eu3+ions was calculated to be 1.768 nm.The quenching temperature(T) of LaTaWO:20 mol%Euis about 440 K.The quantum yield(QY) was measured to be 85.85%.The fabricated white-light-emitting diodes(w-LEDs) possess high color-rendering index(R) of 90,and high correlated color temperature(CCT) of 5810 K,respectively.The Commission Internationale de L’Eclairage(CIE) coordinates are(0.311,0.322).Therefore,the prepared phosphor has a promising application for w-LEDs.