Excited States of 3d3 Electrons in K2SiF6:Mn4+ Red Phosphor Studied by Photoluminescence Excitation Spectroscopy

This paper reports on a study of the photoluminescence excitation (PLE) spectra of Mn4+-activated K2SiF6 phosphor at 20 and 300 K. Measurements of the PLE spectra show that the sharp red emissions (E-2(g) -> (4)A(2g)) at similar to 630 nm are most efficiently excited by irradiation into the spin-allowed transitions (4)A(2g) -> T-4(2g) (similar to 460 nm) and (4)A(2g) -> T-4(1g) (similar to 360 nm). The first efficient excitation band (4)A(2g) -> T-4(2g) is structureless at 300 K but shows a sharp origin and some oscillatory peaks at 20 K. A Fourier transform technique is used for analyzing such oscillatory peaks. The second excitation band (4)A(2g) -> T-4(1g) shows a structureless shape even at a low temperature (20 K). The third excitation band with a peak at similar to 250nm is very weak and could be assigned as the (4)A(2g) -> T-4(1g) transition. The direct excitation of the E-2(g) state is also found to produce the sharp red emissions at similar to 630nm with a negligibly small offset in the configurational coordination. The Franck-Condon analysis makes it possible to accurately determine the zero-phonon line energies in the 3d(3) electron transitions of the MnF62- octahedron. (C) 2011 The Japan Society of Applied Physics