Comparison of Performance between Single- and Multiparameter Luminescence Thermometry Methods Based on the Mn⁵⁺...

Herein, we investigate the performance of single- and multiparametric luminescence thermometry founded on the temperature-dependent spectral features of Ca₆BaP₄O₁₇:Mn⁵⁺ near-infrared emission. The material was prepared by a conventional steady-state synthesis, and its photoluminescence emission was measured from 7500 to 10,000 cm^-1 over the 293-373 K temperature range in 5 K increments. The spectra are composed of the emissions from ¹E → ³A₂ and ³T₂ → ³A₂ electronic transitions and Stokes and anti-Stokes vibronic sidebands at 320 cm^-1 and 800 cm^-1 from the maximum of ¹E → ³A₂ emission. Upon temperature increase, the ³T₂ and Stokes bands gained in intensity while the maximum of ¹E emission band is redshifted. We introduced the procedure for the linearization and feature scaling of input variables for linear multiparametric regression. Then, we experimentally determined accuracies and precisions of the luminescence thermometry based on luminescence intensity ratios between emissions from the ¹E and ³T₂ states, between Stokes and anti-Stokes emission sidebands, and at the ¹E energy maximum. The multiparametric luminescence thermometry involving the same spectral features showed similar performance, comparable to the best single-parameter thermometry.