Mn4+ doped (NH4)2TiF6 and (NH4)2SiF6 micro-crystal phosphors: synthesis through ion exchange at room temperature and their photoluminescence properties

摘要

The synthesis procedures of red phosphors activated by Mn ~(4+) that are carried out especially at room temperature, are significant to industrialization. Herein, we report a facile strategy to obtain two red micro-crystal phosphors: (NH _(4) ) _(2) TiF _(6) :Mn ~(4+) (NTF:Mn) and (NH _(4) ) _(2) SiF _(6) :Mn ~(4+) (NSF:Mn) through ion exchange at room temperature for a few hours. Raw materials NTF and NSF act as host lattices of red micro-crystal phosphors, and activator Mn ~(4+) ions are from K _(2) MnF _(6) /HF and/or mixed KMnO _(4) /HF solution. The reaction mechanism for the synthesis process has been comprehensively discussed in detail. The typical red emitting luminescence of Mn ~(4+) with strong absorption in the blue region and the large size of about 200 μm of red micro-crystal phosphors NTF:Mn make it an attractive candidate material as a red compensator for resin-free white light-emitting diodes with high color rendering index. The dependence of emission intensity on concentration of HF and KMnO _(4) , and measurement temperature has been investigated. The advantage of the proposed strategy is the ability to explore Mn ~(4+) doped red phosphors from low-cost starting materials at room temperature for large scale industrial applications.