A new optical temperature sensor based on the fluorescence intensity ratio of Mn²⁺ and Mn⁴⁺

Abstract

In the course of preparing Mn-doped phosphors, the mix-valence state of Mn n+ ions may be obtained with associated interesting properties. This work prepared a new phosphor Ba 3 MgSb 2 O 9 :Mn (BMS:Mn) by a traditional high-temperature solid-state synthesis method. In this structure, Mn n+ can replace Mg 2+ site as Mn 2+ oxidation state or Sb 5+ site as Mn 4+ . Moreover, the emitting bands of Mn 2+ and Mn 4+ at around 596 and 758 nm are simultaneously observed by using 350 nm as exciting wavelength. Interestingly, the temperature-dependent emitting intensities corresponding to Mn 2+ and Mn 4+ are different at temperatures from 10 to 300 K. With increasing temperature, the intensity of Mn 2+ luminescence has some enhancement at 10-200 K and then decreases gradually, whereas Mn 4+ luminescence goes into rapid decline. By using this character, BMS:0.01Mn can be used as an optical temperature sensor at 10-300 K based on the fluorescence intensity ratio of Mn 2+ and Mn 4+ . The maximum relative sensitivity (S r ) at 125 K is as high as 1.51% K −1 .

Phase transition monitoring and temperature sensing via FIR technology in Bi/Sm‐codoped KNN transparent ceramics

“…[1][2][3][4][5] Thereinto, optical temperature sensors via fluorescence intensity ratio (FIR) are rapidly developed, which is not susceptible to external interference in measurement, enriching the temperature measurement technology that holds significant implications on human daily life as well as scientific inquiry. [6][7][8][9] Moreover, FIR optical temperature sensors that exhibit multiple advantages of simple operation, fast response speed and high spatial resolution possess apparent preponderance over traditional temperature measuring technology, conducive to the harsh working environment and remote temperature monitoring applications. [10][11][12][13] Compared with frequently-used matrices in optical temperature sensors, such as toxic fluorides and fragile glasses that own poor thermal stability, lead-free ferroelectric ceramics display nontoxicity, high mechanical strength and excellent chemical stability, behaving more advantages in broader application areas.…”

“…Luminescent materials have gained extensive application prospects in display lighting, anticounterfeiting, optical information storage, temperature sensing, and other fields on account of their particular optical properties 1–5 . Thereinto, optical temperature sensors via fluorescence intensity ratio (FIR) are rapidly developed, which is not susceptible to external interference in measurement, enriching the temperature measurement technology that holds significant implications on human daily life as well as scientific inquiry 6–9 . Moreover, FIR optical temperature sensors that exhibit multiple advantages of simple operation, fast response speed and high spatial resolution possess apparent preponderance over traditional temperature measuring technology, conducive to the harsh working environment and remote temperature monitoring applications 10–13 …”

Review—Photoluminescence Spectroscopy of Mn2+-Activated Phosphors: Part I. Fundamentals

“…45. Here, the luminescence in these phosphors corresponds to the 4 T 1g ( 4 G) → 6 A 1g ( 6 S) transitions. Similarly, the lowest excitation absorption band is due to the 6 A 1g ( 6 S) → 4 T 1g ( 4 G) transitions.…”

“…A fairly large number of experimental data are available at the present time on the optical transitions between the ground and excited-state configurations of the divalent rare-earth activator ion Mn 2+ in crystals and subsequent light emitting processes in such phosphor materials. 1,2 As the divalent non-rare earth ion, Mn 2+ is an efficient activator for luminescence in the various host crystals, e.g., oxide, 3,4 phosphate, 5,6 nitride, 7,8 oxynitride, 9,10 chalcogenide, 11,12 halide, 13,14 and organic−inorganic hybrid materials. 15,16 Note that the intra-d (3d 5 )-shell transitions in Mn 2+ are sensitive to the magnitude of the crystal field and, as a result, the wavelength of its luminescence light can be tuned to the coordination environment.…”

“…There is a question that is the near-infrared (NIR) emission observed in the Mn-doped LiBaF 3 phosphor surely comes from Mn 2+ ion, but not from Mn 4+ ion. Assuming its NIR emission to be due to the intraa-3d 3 -shell configurational Mn 4+ ion rather than the divalent intra-3d 5 -shell configurational Mn 2+ ion, one can understand the ZPL energy of ∼1.616 eV (∼767 nm) to arise from the optical transitions between the lowest excited state of 2 E and the ground state of 4 A 2 ( 2 E → 4 A 2 ). However, there is an experimental fact that the various Mn 4+ -activated "fluoride" phosphors promised to exhibit red emission and their ZPL emission energies fell in the limited range of ∼1.98 − 2.01 eV.…”