SrAlEu2+(,Dy3+) nanosized particles: Synthesis and interpretation of temperature-dependent optical properties

Sralnanosized particles (nps) undoped as well as doped with eu2+ and dy3+ were prepared by combustion synthesis for the discussion of their intensively debated spectroscopic properties. emission spectra of sraleu2+(,dy3+) nps are composed by a green band at 19 230 cm-1 (520 nm) at room temperature,assigned to anomalous luminescence originated by eu2+ in this host lattice. at low temperatures,a blue emission band at 22 520 cm-1 (444 nm) is observed. contrary to most of the interpretations provided in the literature,we assign this blue emission band very reliably to a normal 4f6(7f5d(t→4f7(8s transition of eu2+ substituting the sr2+ sites. this can be justified by the presence of a fine structure in the excitation spectra due to the different 7flevels (j = 0 6) of the 4f6 core. moreover,fano antiresonances with the 6i(j = 9 / 2,7 / 2) levels could be observed. in addition,the stokes shifts (δ e s = 1 980 cm-1 and 5 270 cm-1 for the blue and green emission,resp.),the huang-rhys parameters of s = 2.5 and 6,and the average phonon energies of h ω = 480 cm - 1 and 470 cm-1 coupled with the electronic states could be reliably determined. © 2015 huayna terraschke et al.