1 research outputs found
Multifunctional Optical Sensors for Nanomanometry and Nanothermometry: High-Pressure and High-Temperature Upconversion Luminescence of Lanthanide-Doped PhosphatesLaPO<sub>4</sub>/YPO<sub>4</sub>:Yb<sup>3+</sup>–Tm<sup>3+</sup>
Upconversion
luminescence of nano-sized Yb<sup>3+</sup> and Tm<sup>3+</sup> codoped
rare earth phosphates, that is, LaPO<sub>4</sub> and YPO<sub>4</sub>, has been investigated under high-pressure (HP, up to ∼25
GPa) and high-temperature (293–773 K) conditions. The pressure-dependent
luminescence properties of the nanocrystals, that is, energy red shift
of the band centroids, changes of the band ratios, shortening of upconversion
lifetimes, and so forth, make the studied nanomaterials suitable for
optical pressure sensing in nanomanometry. Furthermore, thanks to
the large energy difference (∼1800 cm<sup>–1</sup>),
the thermalized states of Tm<sup>3+</sup> ions are spectrally well-separated,
providing high-temperature resolution, required in optical nanothermometry.
The temperature of the system containing such active nanomaterials
can be determined on the basis of the thermally induced changes of
the Tm<sup>3+</sup> band ratio (<sup>3</sup>F<sub>2,3</sub> → <sup>3</sup>H<sub>6</sub>/<sup>3</sup>H<sub>4</sub> → <sup>3</sup>H<sub>6</sub>), observed in the emission spectra. The advantage of
such upconverting optical sensors is the use of near-infrared light,
which is highly penetrable for many materials. The investigated nanomanometers/nanothermometers
have been successfully applied, as a proof-of-concept of a novel bimodal
optical gauge, for the determination of the temperature of the heated
system (473 K), which was simultaneously compressed under HP (1.5
and 5 GPa)