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 S_a and relative sensitivity S_r of SAO:Mn⁴⁺ 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.