Synthesis and the temperature-dependent luminescent properties of SrWO4:Eu3+ ultralong nanowire phosphors

Development of SrWO4:Ho3+/Yb3+ green phosphor for optical thermometry application

In recent years, the growth of luminescent materials for optical thermometry applications has gained substantial attention due to their non-invasive and contactless nature. This research article presents the synthesis, characterization, and potential application of SrWO4:Ho3+/Yb3+ phosphors as temperature-sensitive materials. The inspection of the structural properties is done by X-ray diffraction and Raman and FTIR spectroscopy. The X-ray diffraction signifies the single tetragonal phase of the materials without any impurity or secondary phase. Nine Raman active modes are detected in the Raman spectra of pure SrWO4 and 10 Raman active bands are present in the doped samples. The morphology and elemental composition are visualised by field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy. The spectral properties of these phosphors are evaluated by down-conversion and up-conversion photoluminescence, signifying their suitability for solid state lighting and optical thermometry in various temperature regimes. The phosphors can generate green and yellow light under blue and near-infrared radiation, respectively. The sensitivity of 3.19 × 10-3 K-1 ensures the promising prospects of SrWO4:Ho3+/Yb3+ phosphors for precise and reliable temperature sensing in diverse fields.

Luminescent Thermochromic Silver Iodides as Wavelength-Dependent Thermometers

Luminescent thermochromic materials with a dramatic shift of emission band under different temperatures are highly desirable in temperature sensing fields. However, the design of the synthesis of such compounds remains a great challenge. In this work, two new luminescent thermochromic silver iodides, (emIm)Ag₃I₄ (1) and (emIm)Ag₂I₃ (2) (emIm = 1-ethyl-3-methyl imidazole), have been synthesized under solvothermal conditions. Compound 1 features a [Ag₃I₄]^- anionic layer, while compound 2 possesses an infinite [Ag₂I₃]^- chain structure, both of which are charge balanced by emIm⁺ cations. Particularly, they display luminescent thermochromism with a significant wavelength shift of emission maximum with temperature change. They represent rare examples of infinite layered or chain silver iodides that show luminescent thermochromism. Furthermore, the results indicate that compounds 1 and 2 are promising wavelength-dependent luminescent thermometers.

Probing emission and defects in BaWxMo1–xO4 solid solutions: achieving color tunable luminescence by W/Mo ratio and size manipulation

This work highlights the size, structure, and composition manipulation for designing color-tunable phosphors based on doped scheelite micro- and nanocrystals.