Synthesis Mechanism And Luminescence Properties Of Mn⁴⁺ Ion Doped Fluostannate Red Light Materials

Mn⁴⁺as a luminescent center has excellent spectral characteristics:broad maximum excitation bands in blue region,sharp emission peaks in red region,and high luminescence efficiency,are desired for application in warm WLEDs.Therefore,Mn⁴⁺series doped red phosphors have attracted much attention because of their rich raw materials and mild synthetic conditions.In this paper,we have explored the synthesis of a variety of new Mn⁴⁺doped fluorides red phosphors and their luminescent properties and applications.The Mn⁴⁺activated fluostannate Na₂SnF₆ red phosphor was synthesized at room temperature by a two-step method.The red-emitting phosphor NaKSnF₆:Mn⁴⁺has been obtained from NaF and KF with a certain molecular ratio in HF solution,which exhibits superior optical properties including high color purity with narrow-band emissions as well as better chromaticity coordinates compared to the red phosphors Na₂SnF₆:Mn⁴⁺and K₂SnF₆·H₂O:Mn⁴⁺.The red phosphor BaSnF₆:Mn⁴⁺has been prepared by metal etching.The phase identification,thermal stability,and structure of the phosphor BaSnF₆:Mn⁴⁺have been investigated.The reaction mechanism for the synthesis process has been comprehensively discussed in detail of the red micro-crystal phosphors:?NH₄?₂TiF₆:Mn⁴⁺and?NH₄?₂SiF₆:Mn⁴⁺and a novel red phosphor,NaHF₂:Mn⁴⁺was obtained via substituting Na⁺located at the center of the octahedron coordinated with six F^-ions with Mn⁴⁺in the host lattice of NaHF₂:Mn⁴⁺.The WLED fabricated with YAG:Ce and the as-prepared red phosphors exhibits“warm”white light,which indicates promising application in indoor solid-lighting.