LUMINESCENCE OF FE-DOPED WILLEMITE SINGLE-CRYSTALS

The emission and excitation spectra of Fe-doped Zn2SiO4 (willemite) cr ystals were measured at temperatures ranging from 10 to 298 K. The lum inescence consists of two contributions, both of broadband type: an em ission due to the T-4(1)((4)G) --> (6)A(1)(S-6) interconfigurational t ransition of the d(5) Fe3+ ions in sites having approximate tetrahedra l coordination and a second emission probably due to lattice defects i nduced by the requirement of charge compensation. The excitation spect rum of Fe3+ has been assigned on the basis of the ligand field theory, and the energies of the bands have been fitted with the following val ues of the ligand field parameters: Dq = 743 cm(-1), B = 535 cm(-1), a nd C = 3155 cm(-1) From these data, it is reasonable to suppose that t he Fe3+ ions responsible for the emission are located at the Si4+ dist orted tetrahedral sites. (C) 1995 Academic Press, Inc.