Jump to main content
Jump to site search

Issue 8, 2015
Previous Article Next Article

A low-temperature co-precipitation approach to synthesize fluoride phosphors K2MF6:Mn4+ (M = Ge, Si) for white LED applications

Author affiliations

Abstract

A new class of Mn4+ activated alkali-metal hexafluoride red phosphors are emerging for white light-emitting diodes because of their sharp red line 2Eg4A2g emissions (600–650 nm) excited by irradiation of 4A2g4T1g (320–380 nm) and 4A2g4T2g (380–500 nm) transitions. However, these phosphors have the drawbacks of difficult control of the Mn valence state during synthesis and lack of underlying mechanisms for structure–photoluminescence relationships. In this study, we explore a novel, highly productive route to the quantifiable synthesis of K2GeF6:Mn4+ by the chemical co-precipitation method at room temperature. The prepared yellowish K2GeF6:Mn4+ powders exhibit a hexagonal shape and high crystallinity without significant defects. The photoluminescence thermal stability and white light-emitting diodes applicability of K2GeF6:Mn4+ suggest that it is a promising commercial red phosphor because of its efficient emission intensity, high color purity and excellent thermal stability. Structural analyses and theoretical calculations reveal that the red shift of the K2GeF6:Mn4+ red phosphor compared with K2SiF6:Mn4+ is due to the longer Ge–F distance and lower effective Mulliken charge of F ions in coordination environments of the MnF62− octahedron. The split feature in K2GeF6:Mn4+ is due to the hexagonal distortion in the host. The structure–photoluminescence mechanism is predicted to be general in hexafluoride red phosphors to tune the optical properties through cationic substitutions and crystal structure adjustments.

Graphical abstract: A low-temperature co-precipitation approach to synthesize fluoride phosphors K2MF6:Mn4+ (M = Ge, Si) for white LED applications

Back to tab navigation

Supplementary files

Publication details

The article was received on 09 Nov 2014, accepted on 14 Jan 2015 and first published on 16 Jan 2015


Article type: Communication
DOI: 10.1039/C4TC02551B
Author version
available:
Download author version (PDF)
Citation: J. Mater. Chem. C, 2015,3, 1655-1660

  •   Request permissions

    A low-temperature co-precipitation approach to synthesize fluoride phosphors K2MF6:Mn4+ (M = Ge, Si) for white LED applications

    L. Wei, C. C. Lin, M. Fang, M. G. Brik, S. Hu, H. Jiao and R. Liu, J. Mater. Chem. C, 2015, 3, 1655
    DOI: 10.1039/C4TC02551B

Search articles by author

Spotlight

Advertisements