Phosphor

Phase (matter)

Engineering

Materials science

Chromatography

Metastability

Substitution (logic)

Stability (learning theory)

Color rendering index

Computer science

Photoluminescence

Chemical engineering

Hexagonal crystal system

Thermodynamics

Physics

Organic chemistry

Emission intensity

Thermal

Analytical Chemistry (journal)

Crystallography

Chemistry

Programming language

Thermal stability

Hexagonal phase

Optoelectronics

Machine learning

Chemical Engineering Journal

K2GeF6:Mn4+ (KGFM) phosphors with very poor water-proof property in HF solution transform automatically from P63mc hexagonal phase to P3¯m1 trigonal phase. By substituting Ge4+ ion with Si4+ ion, the metastable P63mc hexagonal K2(Ge1-xSix)F6:Mn4+ (KGSFM) with an obvious zero-phonon line peaking at 623.8 nm is stabilized in HF solution. When x = 0.3, the photoluminescence intensity of KGSFM keeps 78% after 168 h in water as well as it increases by 14% at 150 °C (423 K) more than that of KGFM. By using KGSFM the fabricated WLEDs exhibit the high color-rendering index (Ra = 92) and low correlated color temperature (CCT = 3810 K). These results demonstrate that KGSFM solid solution with efficient red emission, meritorious water-proof and high thermal stability is a promising phosphor for the commercial application in the WLEDs and wide-gamut displays.

Improved phase stability of the metastable K2GeF6:Mn4+ phosphors with high thermal stability and water-proof property by cation substitution