PhotoluminescencepropertiesandthermalstabilityofEu3+-activatedLa7Ta3W4O30red-emittingphosphorsfornear-UV-excitedw-LEDs

Novel trivalent europium(Eu3+)-activated La7 Ta3 W4 O30:xEu3+（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 La7 Ta3 W4 O30:Eu3+ phosphors show five emission peaks under near-ultraviolet（n-UV） at 397 nm,and these peaks are ascribed to the transitions of 5 D0-7 Fj（j=0,1,2,3 and 4） by Eu3+ ions.The optimal doping concentration of Eu3+ is 20 mol%,and the critical distance of the energy transfer between the Eu3+ions was calculated to be 1.768 nm.The quenching temperature(T0.5) of La7 Ta3 W4 O30:20 mol%Eu3+ is 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（Ra） 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.