Enhanced luminescence by monovalent alkali metal ions in Sr_2SiO_4:Eu~(3+) nanophosphor prepared by low temperature solution combustion method

摘要

A series of red light emission phosphors of Sr_2SiO_4:Eu~(3+) (1-5 mol%) and Sr_2SiO_4:Eu~(3+):M+ (M+ = Na+, IC and Li~+) were prepared through simple low temperature solution combustion method and their luminescence properties were studied. The powder X-ray diffraction (XRD) results revealed the formation of highly crystalline Sr_2SiO_4:Eu~(3+) nanophosphor having an average particle size 45-60 nm and strain was measured to be (2.4-3.1) x 10~3. The SEM pictures of Sr_2SiO_4:Eu~(3+) and Sr_2SiO_4:Eu~(3+): M~+ showed porous in nature and irregular shaped particles. The phosphors can be effectively excited by the light of 395 nm and show the characteristic emission peaks assigned to transitions of ~5D_0 -> ~4F_j {] = 0, 1, 2, 3, 4). The excitation and emission spectra indicate that the phosphors can be effectively excited by UV (~395 nm) light which emits an intense red light peaked at ~614 nm. The Eu~(3+) concentration quenching mechanism was verified to be multipole-multipole interaction and critical energy transfer distance (R_c) was 16.43 nm. The effects of different concentration of Eu~(3+) and charge compensations on luminescence properties were discussed. The highest PL intensity was recorded for 4 mol% Eu~(3+) ions. Further, Li~+ (0.03) has the best charge compensation effect followed by Na~+ and K~+ respectively. The y-induced studies showed three glow peaks at 211, 163 and 243 (shouldered peaks) respectively at a warming rate of 5 °C s~(-1). The glow peak intensity at 163 °C increases linearly up to 3 kGy and after that it decreases. Up to 3 kGy, the phosphor was quite useful for radiation dosimetry.