Low temperature red luminescence of a fluorinated Mn-doped zinc selenite

M-2(SeO3)F-2 (M = Zn (1), Mn (2)) stoichiometric phases together with the Zn2-xMnx(SeO3)F-2 compound doped at various concentrations (x = 0.002-0.2) were synthesized by employing mild hydrothermal conditions. These compounds have been characterized by scanning electron microscopy (SEM), Rietveld refinement of the X-ray powder diffraction patterns, ICP-Q-MS, thermogravimetric and thermodiffractometric analyses, and IR, UV/vis and electron paramagnetic resonance (EPR) spectroscopies. Compounds 1 and 2 crystallize in the orthorhombic Pnma space group with lattice parameters: a = 7.27903(4), b = 10.05232(6) and c = 5.26954(3) angstrom for the zinc species and a = 7.50848(9), b = 10.3501(12) and c = 5.47697(6) angstrom for the manganese phase, with Z = 4. The crystal structures of these compounds are isotypic and are built up from a 3D framework constructed by (010) sheets of [MO3F3] octahedra linked up by [SeO3] building units. Luminescence measurements of Mn-2(SeO3)F-2 were performed at different temperatures between 10 and 150 K. At 10 K, the emission spectrum consists of a broad band peaked at around 660 nm related to the T-4(1g) -> (6)A(1g) transition in octahedrically coordinated Mn2+. Moreover, the influence of temperatures up to 295 K and the Mn concentration on the luminescent properties of the Zn2-xMnx(SeO3)F-2 system were systematically studied. Magnetic measurements of 2 show antiferromagnetic coupling as the major interactions exhibiting a spin canting at low temperature.