Thermometry of red nanoflaked SrAl12O19:Mn4+ synthesized with boric acid flux

This paper presents the luminescence properties and potential of red SrAl12O19:Mn4+ (SAO:Mn4+) phosphor for optical thermometry application. The SAO crystal consisted of a spinel block along with two mirror-like blocks. The Al3+/Sr2+ molar ratio of the precursor solution affected the crystalline-phases, morphology, and photoluminescence of the phosphor. The addition of flux H3BO3 promoted the growth of hexagonal-nanoflakes and enhanced the external quantum efficiency of phosphor 2.6-fold. The absolute sensitivity Sa and relative sensitivity Sr of SAO:Mn4+ showed a linear function of the temperature. The value of Sa was 4.17 × 10−3 K−1, and the maximum Sr was 2.70 × 10−3 K−1 at 393 K. A stable emission color was observed even with a change in temperature and a bright red light was seen in both daylight and a darkroom.