Bifunctional optical probe based on La3Mg2SbO9:Mn4+ phosphors for temperature and pressure sensing

Photoluminescent materials, serving as optical probes, constitute a significant medium for reliable remote sensing of fundamental state parameters such as temperature and pressure. Herein, we report a novel Mn4+-activated perovskite-type La3Mg2SbO9 phosphor (LMS:Mn4+) for bifunctional application in both thermometry and manometry. Upon excitation with 341 nm, LMS:Mn4+ (0.7% Mn4+) emits a bright narrow-band red light peaking at 705 nm with an FWHM (full width at half maximum) of 32 nm. As a thermometer, when the temperature surpasses 298 K, non-radiative transitions from the 2Eg excited state lead to a sharp decrease in decay lifetimes with increasing temperature. This allows for lifetime-based luminescence thermometry with a relative sensitivity of 2.52% K−1 at 391 K. Moreover, LMS:Mn4+ was processed into a temperature-sensing coating and its non-contact thermometry functionality was validated. In manometry applications, the LMS:Mn4+ probe experiences substantial pressure-dependent redshift with a sensitivity of 1.20 nm/GPa in the testing range of 9.48 GPa, which is about 3.3 times that of conventional ruby probes. Furthermore, its FWHM consistently remains below 37 nm, which contributes to a high reliability of pressure measurements. The above results indicate that the LMS:Mn4+ constitutes a promising bifunctional luminescence probe material in thermometry and manometry.