Yellow Luminescence from LaAlO3:Sm3+ Nano-Phosphors Prepared by Sol-Gel Technique

LaAlO3Sm3+, nano-phosphors with varying dopant concentrations of Sm3+ from 1 to 20 mol % were prepared by Sol-Gel Synthesis and the samples were further heated to 600, 700, and 1000 0C to improve the crystallinity of the materials. The advantages of gel combustion base process have been applied to obtain nano particles in the pure homogeneous form. Finally the phosphor was characterized by XRD, SEM, PL measurement to check the crystallinity, particles size and luminescence intensity of the phosphor respectively. XRD results reveal that the sample begins to crystallize at 600C, and pure LaAlO3 phase can be obtained at 700C. SEM images indicate that the Sm3+ -doped LaAlO3 phosphors are composed of aggregated spherical particles with sizes ranging from 40 to 80nm. Under the excitation of UV light (245nm) and low-voltage electron beams (13kV), the Sm3+ -doped LaAlO3 phosphors show the characteristic emissions of phosphor consist of five emission peaks, which are attributed to the transitions from 4G5/2 state to 6HJ (J=5/2, 7/2, 9/2, 11/2, 13/2) states of Sm3+ ions with Yellow, Orangish-Yellow, Orangish-red and red color having emission peak located at 565, 598, 615, 653, 707 nm respectively. Among these emission peaks, the transition emission 4G5/26HJ (J=5/2, 7/2, 9/2) for peak at 565, 598, 615nm is strongest for Yellow, Orangish-Yellow and Orangish-red emission is due to the magnetic dipole transition of Sm3+ ion having a magnetic dipole (MD) allowed one and also an electric dipole (ED) dominated one but the other weak transition 4G5/26H11/2& 4G5/26H13/2 (653nm, 707nm red) is purely an ED one. Highest photoluminescence intensity is observed with 3 mol % doping of Sm3+ made LaAlO3Sm3+, a strong competitor for promising Yellow, Yellow-orange& also for Orange-red colored display applications.