Structural change induced by thermal annealing of red-light-emitting ZnSnF 6 ∙ 6H 2 O:Mn 4+ hexahydrate phosphor

Effects of thermal annealing on the red-emitting ZnSnF 6 ∙ 6H 2 O:Mn 4+ hexahydrate phosphor properties were investigated using X-ray diffraction measurement (XRD), photoluminescence (PL) analysis, and Raman scattering spectroscopy. Thermal annealing was performed at T a = 50 to 400 °C in air for 1 h. Mn 4+ -related red emission wavelengths were redshifted about 5 nm after annealing at T a ≥ 200 °C with greatly decreased emission intensities. This change in PL spectral feature was attributed to the dehydration of the hexahydrate phosphor, supported by the XRD and Raman scattering results. The XRD and PL intensity analyses determined thermal decomposition energies of ∼0.3 eV from the ZnSnF 6 ∙ 6H 2 O hexahydrate to anhydrate and of ∼0.9 eV from the ZnSnF 6 anhydrate to metallic fluorid/oxide (ZnF 2 /SnO 2 ). A comparative discussion was given on the PL properties of two different Mn 4+ -activated phosphors, Ba–IV–F 6 :Mn 4+ anhydrate and Zn–IV–F 6 ∙ 6H 2 O:Mn 4+ hexahydrate phosphors with IV = Si, Ge, and Sn.