Spectroscopic in-depths of upconverting NaZr2(PO4)3 phosphors for LIR-based thermometry.

This study employed solid-state synthesis to develop the green emitting Er3+-Yb3+:NaZr2(PO4)3, NASICON material. Using Rietveld refinement, the crystallographic variables of the synthesized phosphors were precisely calculated. The upconverting phenomenon was seen with naked eye when exposed to 980 nm laser radiation. The intermediate excited state dependency on the unusual photon number dependence on the green and red emission has been understood using the steady-state rate law equations. Further, the temperature sensing performances with good repeatability were compared with different laser densities, and it was found that the prepared phosphors could be an ideal material for upconverting and temperature sensing applications.

Temperature sensing using bulk and nanoparticles of Ca0.79Er0.01Yb0.2MoO4phosphor.

Optical temperature sensing is widely realized by using upconversion (UC) emission in lanthanide-doped phosphors. There are various parameters that are responsible for UC intensity of the phosphor like particle shape and size, type of symmetry that exist at the site position, distribution of lanthanide ions in the phosphor, and so on. However, a comparative study of the bulk and nanostructure on the temperature sensing ability of such phosphor is rare. In the present work, we have taken Ca0.79Er0.01Yb0.2MoO4phosphors as a model system and synthesized its bulk (via solid-state reaction method, named SCEY) and nanostructures (via solution combustion route, named CCEY). We further studied their phase, crystal structure, phonon frequency, optical excitation, and emission (upconversion & downshifting) properties. Finally, the optical temperature sensing behavior of SCEY and CCEY, in the range 305 K-573 K, have been compared. The maximum relative sensitivity of the phosphor SCEY and CCEY are 0.0061 K-1at 305 K and 0.0094 K-1at 299 K, respectively, while, the maximum absolute sensitivities are 0.0150 K-1at 348 K, and 0.0170 K-1at 398 K, respectively. We thus conclude that the temperature sensing ability of nanoparticle-based Ca0.79Er0.01Yb0.2MoO4phosphor is better compared to its bulk phosphor.

Tailoring of upconversion luminescence of Al3+engineered titanate phosphor for non-invasive thermometry.

The ability of rare-earth-doped ferroelectric oxides to achieve outstanding upconversion (UC) performances under NIR irradiation despite possessing intrinsic electric properties drives researchers all over the globe to work in this field. The structural and spectroscopic characteristics of the Bi4Ti3O12phosphor integrated with Er3+, Yb3+, and Al3+have been thoroughly investigated in this study. The considerable increase in UC emission ∼three times caused by the addition of Al3+ions has been observed and discussed. The processes connected with the UC emission related to the pump power variation have been realized using the rate law equation. Aside from having high sensitivity of 0.011 K-1at room temperature, the prepared phosphor possesses excellent thermal stability, i.e., it retains ∼73% of its initial intensity with the addition of Al3+ions.