Spark plasma sintering of MgAl2O4:Mn2+ transparent ceramic phosphors with low thermal quenching, narrow-band green emission
LIN H. 1, DUAN Y. 1, QIANG M. 1, YIN X. 1
1 University of Shanghai for Science and Technology, China, SHANGHAI, China
Mn2+ activated MgAl2O4 phosphors, in the forms of powders and ceramics, have been investigated by other colleagues` pioneering work, which disclosed that this material is promising for the applications in LCD backlights or dosimetry. With respect to the various kinds of phosphors forms, including powders, single crystals, glass, ceramics and glass ceramics, etc., intensive efforts have been made on ceramic materials which exhibit much higher physicochemical thermal stability and higher heat release capability than the counterparts of the transparent silicone encapsulated phosphors, which suffers from severe thermal degradation under high-power/high brightness light excitation. The cubic MgAl2O4 spinel structure is feasible to be densified into transparent ceramics and has high thermal conductivity and low thermal expansion.
In this work, the Mn doped magnesium aluminate (MgAl2O4) spinel transparent ceramic phosphors were fabricated via spark plasma sintering (SPS). The phase composition, microstructures and luminescence and thermal properties of the ceramic phosphors were investigated and discussed.
The ceramic samples show narrow-band green emission under the 450?nm blue light excitation, which is corresponding to 4T1(4G)-6A1(6S) transition of Mn2+ in the tetrahedral site. The emission peak of the Mg0.93Al2O4:0.07Mn2+ ceramic sample was located at 525?nm with the full-width at half-maximum (FWHM) value of 36?nm. The internal quantum yield (IQY) of Mg0.93Al2O4:0.07Mn2+ reached 63%. The emission intensity remained ∼98% at 150 °C compared to its initial value at room temperature, showing excellent thermal quenching performance. The results indicated that MgAl2O4:Mn2+ ceramic phosphor is a promising candidate for high brightness, wide gamut display backlight applications.