Spectral analysis for broadband fluorescence: temperature sensing with the YAG:Ce phosphor as an example

Abstract

Temperature-dependent fluorescence of YAG:Ce was studied as an example of a spectral characterization method. According to the steady-state emission at various temperatures, four types of temperature sensing functions were retrieved using behaviors of 1) wavenumber at emission band maximum magnitude, 2) wavenumber of emission band barycenter, 3) emission bandwidth, and 4) the ratio of intensities at different wavelengths in the emission band. All four types of functions demonstrate a near linear relationship with temperature in the measured temperature range. Function No. 2 shows finer precision than function No. 1, while they have the same meaning in physics. Mechanisms of the temperature dependence are discussed after a brief review of emission peak shifts of Ce 3+ -doped garnets. Function No. 3 shows an abnormal narrowing of the band with increasing temperature which can be related to the narrowing ground levels' splitting gap. In the experiment, the two novel spectral characterization methods showed their advantages: the barycenter technique contains the smallest uncertainty, and the self-referenced intensity ratio technique provides flexible ratiometric sensing functions for various measurement needs. Seshadri, "Rapid microwave preparation of highly efficient Ce 3+ -substituted garnet phosphors for solid state white lighting," Chem. Mater. 24(6), 1198-1204 (2012). 10. S. P. Ying, P. T. Chou, and H. K. Fu, "Influence of the temperature dependent spectral power distribution of light-emitting Diodes on the illuminance responsivity of a photometer," Opt. Lasers Eng. 51(10), 1179-1184 (2013). Defects Solids 158(1-6), 39-47 (2003). 14. M. Grinberg, "High pressure spectroscopy of rare earth ions doped crystals -new results," Opt. Mater. 28(1-2), 26-34 (2006) 8-12 (2015).

Bandshift Luminescence Thermometry Using Mn4+:Na4Mg(WO4)3 Phosphors

“…Notably, Mn 4+ -activated phosphors have not been investigated at all as bandshift thermometers; their use has been limited to ratiometric bandshape and lifetime optical thermometry. Among the very few lineshift thermometers based on activator emission that have been reported are Eu 3+ :Y 2 O 2 S, 36 Nd 3+ :LaF 3 , 18 Ce 3+ :Y 3 Al 5 O 12 , 37 and Eu 3+ /Dy 3+ :YVO 4 . 38 As expected, sensitivity values for Na 4 Mg 0.940 Mn 0.030 (WO 4 ) 3 are much higher than those reported for thermosensitive phosphors based on f− f and f−d transitions (e.g., 0.007 nm K −1 for Nd 3+ :LaF 3 ).…”

Structure-dependent luminescence of Eu3+-doped strontium vanadates synthesized with different V : Sr ratios – application in WLEDs and ultra-sensitive optical thermometry

“…13). 73–82 Moreover, the approach of using the absolute sensitivity parameter is a good way for automatic computing, and fast data processing, because of the single range of spectra used for calculations.…”

“…13). [73][74][75][76][77][78][79][80][81][82] Moreover, the approach of using the absolute sensitivity parameter is a good way for automatic computing, and fast data processing, because of the single range of spectra used for calculations. The relative thermal sensitivity (S r ) as a function of temperature was calculated according to eqn (7):…”

Tm2+ Activated SrB4O7 Bifunctional Sensor of Temperature and Pressure—Highly Sensitive, Multi‐Parameter Luminescence Thermometry and Manometry

“…[58,59] The relative thermal sensitivity increases with temperature, until it reaches the maximal value of S r max = 4.16% K −1 at 337 K. Afterward, S r decreases to 3.36% K −1 at 400 K. As shown in Table 1, compared to other thermometers based on luminescence decay time, our material not only shows 4 parameters for temperature determination, but also, in each category, is one of the thermometers with the highest sensitivity within a relatively wide operating T-range. It is worth noting that the number of the reported optical thermometers in Table 1 are limited, due to the limited numbers reported for lanthanide or other transition metal ions based optical thermometer based on bandshift [32,48,51,60,61] and FWHM. [60][61][62] Please note that the developed sensor SrB 4 O 7 :Tm 2+ is a very rare case among luminescence thermometers, where the relative sensitivity based on the decay time is higher than that obtained using the LIR.…”

“…It is worth noting that the number of the reported optical thermometers in Table 1 are limited, due to the limited numbers reported for lanthanide or other transition metal ions based optical thermometer based on bandshift [32,48,51,60,61] and FWHM. [60][61][62] Please note that the developed sensor SrB 4 O 7 :Tm 2+ is a very rare case among luminescence thermometers, where the relative sensitivity based on the decay time is higher than that obtained using the LIR. Thus, applying the developed optical thermometer, it is possible to measure temperature with very high sensitivity over the wide T-range.…”