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Rare earth doped luminescent sensing materials as non-contact thermometers have attracted extensive research interests due to their wide applications in areas like military, medical care, aerospace, etc. How to expand the working temperature range and improve the sensitivity has become the focus. In this work, we synthesized a series of apatite-structured luminescent temperature sensors M 2 La 7.9 Ce 0.1 (SiO 4) 6 O 2 (M = Ca, Sr, Ba) via isomorphic substitution. By monitoring the differential changes of emission intensities from Ce3+ at the 7-coordinate and 9-coordinate site respectively when temperature varies, the real-time temperature can be determined. These materials were proven to possess the maximum absolute sensitivity up to 0.825 × 10−3 K−1, 2.63 × 10−3 K−1 and 4.33 × 10−3 K−1, respectively. Meanwhile interesting regular patterns were observed for their temperature sensitivities with the substitution of Ca, Sr and Ba. Furthermore, through studying the temperature sensitivity of Ba 2 La 8 (SiO 4) 6 O 2 : x Ce3+ samples with different concentrations, it was found that when the Ce3+ content was at the optimal doping concentration of 0.7, the absolute sensitivity of the sample reached 14.64 × 10−3 K−1 at 573 K. This finding has opened up a new avenue for designing fluorescent temperature sensors. Synopsis: In this work, Ce3+ were doped into a series of phosphor-structured matrices containing two cationic sites (7-coordinated Ce1 and 9-coordinated Ce2 sites) via the solid-state high-temperature method. Due to the different temperature dependencies of luminescence intensities between the two Ce3+ sites, their intensity ratio could be used for temperature calibration. [Display omitted] [ABSTRACT FROM AUTHOR]