There is a challenge
for noncontact temperature-sensing techniques
and the related materials, in which a highly reliable contactless
thermometer probe with low cost and high sensitivity is in demand.
Here, the Lu3Al5O12:Ce3+/Mn4+ phosphor has been designed and prepared for the
high-performance fluorescence temperature-sensing application in a
novel one-pot, self-redox, solid-state process. Benefiting from the
different electron–lattice/phonon interactions of Ce3+ and Mn4+, two distinguishable emission peaks with significantly
different temperature responses originating from Ce3+ and
Mn4+ are realized. Applying the fluorescence intensity
ratio of Mn4+ versus Ce3+ and the decay lifetime
of Mn4+ emission as the temperature readout, a dual-mode
optical temperature-sensing mechanism was proposed and studied in
the temperature range of 100–350 K. The maximum relative sensitivities
(S
r) are derived as 4.37 and 3.22% K–1 respectively, as well as a large chromaticity shift
visible to naked eyes (ΔE = 153 × 10–3 in 100–350 K) is observed. This is the first
report of a Ce3+,Mn4+ co-doped dual-emitting
phosphor, and its unique optical thermometric features demonstrate
the high potential of Lu3Al5O12:Ce3+/Mn4+ as an accurate and reliable thermometer
probe candidate.