Composition Regulation Triggered Multicolor Emissions in Eu²⁺-Activated Li₄(Sr_1–xCa_1+x)(SiO₄)₂ for a Highly Sensitive Thermometer

Abstract

We report on the development of a new class of highly sensitive luminescent optical thermometers building blocks via engineering multicolor-emitting Eu 2+ -activated Li 4 (Sr 1−x Ca 1+x )(SiO 4 ) 2 phosphors. Since the Eu 2+ ions occupied two diverse sites in the host, the resultant compounds emitted two distinct emissions in blue and yellow regions. In particular, the blue emission is ascribed to the Sr 2+ sites, while the yellow emission is attributed to Ca 2+ sites. By adjusting the content ratio between Ca 2+ and Sr 2+ ions, the emitted color can be changed from yellowish-brown to blue upon 365 nm excitation. Furthermore, with the aid of the fluorescence intensity rate technology, the temperature-sensing ability of the synthesized phosphors is revealed by means of detecting the inequable responses of the blue and yellow emissions to the temperature. When x = 0.4, the maximum relative sensitivity of the developed samples is 1.181% K −1 . Importantly, the sensor sensitivities of the resultant phosphors can be adjusted by engineering the composition. These features elaborate that the Eu 2+ -activated Li 4 (Sr 1−x Ca 1+x )(SiO 4 ) 2 phosphors with high sensor sensitivities present as one of most promising candidates for noninvasive optical thermometers.

Luminescent Nanothermometer Operating at Very High Temperature—Sensing up to 1000 K with Upconverting Nanoparticles (Yb3+/Tm3+)

“…Temperature is a crucial parameter for most of industrial processes, like sintering, formation of metal alloys, catalytic reactions, formation of new materials under extreme conditions, and so forth. Hence, its rapid, accurate, and online monitoring is a challenging task for many specialists working in various fields of science, industrial researchers, and material engineers. − For these purposes, various luminescence thermometry techniques have been proposed, developed, and applied. − However, in general, because the luminescence of materials is significantly quenched at increasing temperature, these optical methods are usually limited to low- (cryogenic to biological; below ≈350 K) and mild-temperature (≈400–800 K) ranges. − …”

Facile modulation the sensitivity of Eu2+/Eu3+-coactivated Li2CaSiO4 phosphors through adjusting spatial mode and doping concentration

“…As described in Fig. S2a, only one peak centered at 57.8 eV, which was attributed to the Li + 1 s, was observed in the high-resolution XPS spectrum 22 . The XPS spectrum presented in Fig.…”

“…The XPS spectrum presented in Fig. S2b was dominated by an intense peak with the binding energy of 348.7 eV which was ascribed to the Ca 2+ 2p 3/2 22 . The existence of the Si 4+ 2p 3/2 in the resultant compounds was confirmed by the binding energy at approximately 104.8 eV, as displayed in Fig.…”

Thermal imaging study of Sm2+ doped SrB4O7 based on time-resolved technology

“…In this context, the decay lifetime of certain rare earth ions can be highly sensitive to temperature changes, such as Eu 2+ (ref. [8][9][10][11][12] and Sm 2+ . [13][14][15][16][17] The decay lifetime of rare-earth ions can hardly be affected by black body radiation, flame radiation, and sample contamination, which are almost impossible to neglect in many other optical sensing systems.…”