In this study, CaMoO 4 : Eu 3+ phosphors with molar concentrations of 0.01 %, 0.03 %, and 0.1 % were synthesized via the hydrothermal process. The variable temperature PL spectra demonstrated a pronounced decline in the luminescence of MoO 4 2− with the temperature rising, suggestive of typical thermal quenching behavior, whereas the luminescence of Eu 3+ showcased an emerging trend characterized by an initial increase followed by a decline. This phenomenon was attributed to the intensified energy transfer effect from MoO 4 2− to Eu 3+ as the temperature increased. The thermal quenching trends between MoO 4 2− and Eu 3+ exhibited distinct differences, leading to the acquisition of high relative sensitivity when utilizing the FIR of MoO 4 2− and Eu 3+ for temperature sensing. It was found in the experiment that samples with higher Eu 3+ doping concentrations exhibited higher S r . In the CaMoO 4 : 0.1 % Eu 3+ sample, the S r-max reached 3.19 % K −1 at 303 K, which was an excellent value among inorganic materials. The findings of this paper indicate the potential application of CaMoO 4 : Eu 3+ phosphors for optical thermometry.
Xiaoqing Guo,Shuangju Song,Xue Wang,Xue Jiang,Wenqing Lv,Xiaoya Yu,Yuanyuan Han,Liyong Wang
A novel inorganic dual-functional fluorescent chemosensors CaMoO 4 :Eu 3+ has been prepared via solid-state reaction by the assistance of gum arabic (GA). The fluorescence of as-prepared CMO:Eu 3+ was selectively quenched by Fe 3+ and Cr 2 O 7 2− ions in aqueous, resulting in the simultaneous detection of Fe 3+ and Cr 2 O 7 2− ions. The F − anions can recover the fluorescence when Fe 3+ quenching the fluorescence at 615 nm. Moreover, CMO:Eu 3+ displayed high sensitivity for Fe 3+ and Cr 2 O 7 2− assay and the detection limits were 8.26 and 4.78 μM, respectively. The fluorescence quenching mechanism was ascribed to the competitive adsorption between CMO:Eu 3+ and targets. Results indicated that CMO:Eu 3+ could be a promising candidate in Fe 3+ and Cr 2 O 7 2− ions assay in environmental systems.
In this paper, Y 3+ ions doped CaMoO 4 :Eu 3+ with controlled microstructures were prepared via a hydrothermal method . All samples were fully characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV–vis diffuse reflectance spectroscopy, and photoluminescence measurement. The luminescent performance improvement aroused by doping was systematically investigated after inducing Y 3+ as co-doping ions in CaMoO 4 :Eu 3+ lattice. It is found that the lattice of Y 3+ doped CaMoO 4 :Eu 3+ nanocrystals contracted with increasing the Y 3+ concentration, resulting in a red shift of 1 A 1 → 1 T 1 transition from the valence band to the conduction band. Meanwhile, excitation band at 300 nm corresponding to the typical 1 A 1 → 1 T 1 transition also shifted to lower energy, originating from the charge-transfer between MoO 4 2− group and Eu 3+ ions. When the Y 3+ doping concentration was less than 0.05, the quantum efficiency of Y 3+ doped CaMoO 4 :Eu 3+ nanocrystals was all superior to pure CaMoO 4 :Eu 3+ nanocrystals, which can be assigned to the lattice structure contraction, co-doping effect, doping concentration variation. However, as the content of Y 3+ ions further increasing, Y 3+ ion should act as a luminescence killer, and therefore resulting in a nonradiative de-excitation.
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