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

This paper presents the luminescence properties and potential of red SrAl 12 O 19 :Mn 4+ (SAO:Mn 4+ ) phosphor for optical thermometry application. The SAO crystal consisted of a spinel block along with two mirror-like blocks. The Al 3+ /Sr 2+ molar ratio of the precursor solution affected the crystalline-phases, morphology, and photoluminescence of the phosphor. The addition of flux H 3 BO 3 promoted the growth of hexagonal-nanoflakes and enhanced the external quantum efficiency of phosphor 2.6-fold. The absolute sensitivity S a and relative sensitivity S r of SAO:Mn 4+ showed a linear function of the temperature. The value of S a was 4.17 × 10 −3 K −1 , and the maximum S r 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.