Yb3+/Tm3+ and Yb3+/Ho3+ doped NaY9(SiO4)6O2 phosphors: Upconversion luminescence processes, temperature-dependent emission spectra and optical temperature-sensing properties

Structural, electronic and optical properties of BaRE6(Ge2O7)2(Ge3O10) (RE = Tm, Yb, Lu) compounds and BaYb6(Ge2O7)2(Ge3O10):Tm3+ and BaLu6(Ge2O7)2(Ge3O10):Yb3+,Tm3+ phosphors: potential applications in temperature sensing

“…The main reason for such behavior is the thermal population of 3 F 2,3 states due to transitions from the underlying 3 H 4 state. According to the literature, 47–50 the relative population of thermally coupled states should follow the Boltzmann type population distribution, and consequently, the ratio of the intensity of fluorescence at 673–730 nm and 750–850 nm (FIR) should follow the equation:where B is a constant, Δ E is the energy gap between 3 F 2,3 and 3 H 4 levels, T is the absolute temperature, and k B is the Boltzmann constant (8.617 × 10 −5 eV K −1 ).…”

Anhydride-Terminated Solid-State Carbon Dots with Bright Orange Emission Induced by Weak Excitonic Electronic Coupling

“…However, rare earth elements are non-renewable, expensive, and have low earth abundance, creating an urgent demand for rare earth substitution. In recent years, more and more semiconductor quantum dots, such as CdSe and Pb-containing perovskites, have been explored as multicolor emitting phosphors . However, the toxicity from heavy metals in such quantum dots imposes a serious problem, limiting their application potential. − Up to now, the development of low-cost, environmentally friendly, high-earth-abundance, and high-performance solid-state fluorescent materials is still a fundamental challenge in the field of solid-state fluorescent materials.…”

Up-Conversion Luminescence Processes in NaLaF4 Doped with Tm3+ and Yb3+ and Dependence on Tm3+ Concentration and Temperature

“…Temperature effects on up-conversion luminescence have been observed in various materials (e.g., polycrystalline powder, glass ceramics, nanoparticles) doped with thulium ions. [18][19][20][21][22] Up-conversion luminescence spectra measurements at higher temperatures were performed to verify whether sample temperature variation could significantly affect the intensity of up-conversion luminescence bands. For this experiment, the heater head was slightly covered with NaLaF 4 :Tm 3þ ,Yb 3þ , almost invisible to the naked eye, but under 976 nm excitation the blue Tm 3þ up-conversion luminescence could be observed with the naked eye.…”