Liu Chen,Ji Yulong,Feng Xia,Liu Jingsong,Shen Yichun,Xia Xuerong,Wang Lixi,Zhang Qitu
Lanthanide ion-doped Sc 2 Mo 3 O 12 upconversion (UC) luminescent materials exhibit a unique negative thermal quenching phenomenon, making them highly promising for applications in fluorescence thermometry. However, the luminescence intensity of Sc 2 Mo 3 O 12 phosphor is relatively low at room temperature, so it is urgently necessary to enhance the intensity of the phosphor at room temperature. In this study, Sc 2 Mo 3 O 12 :Yb/Er/Al phosphors were synthesized via the solid-state reaction method, and the effects of Al 3+ ion doping on their phase composition and upconversion fluorescence properties were investigated by X-ray diffraction (XRD) analysis and upconversion fluorescence spectra evaluation. The results show that the incorporation of Al 3+ ions enhanced the UC intensity at room temperature and improved the fluorescence thermometry performance. The doping of Al 3+ ions disrupts the lattice symmetry and reduces the distance between sensitizer ions (Yb 3+ ) and activator ions (Er 3+ ), increasing the UC intensity by approximately 4.2 times. In addition, the dependence of fluorescence properties of ScAl 0.6 Mo 3 O 12 :18%Yb 3+ /2%Er 3+ samples on temperature were tested, the negative thermal quenching effect was verified, and the thermal enhancement mechanism was explored. The maximum absolute and relative sensitivities of the ScAl 0.6 Mo 3 O 12 :18%Yb 3+ /2%Er 3+ reached 0.00635 K −1 at 372 K and 0.00829%K −1 at 300 K, respectively, indicating the potential of the phosphor for applications in optical thermometry.
In this study, Ni–Zn–Co ferrite doped with (Al 3+ ) was synthesized by solid-phase synthesis method and its structure was analyzed. By analyzing the X-ray diffraction (XRD) data, it was explained that the Ni 0.45 Zn 0.40 Co 0.15 Fe 2-x Al x O 4 (0 ≤ x ≤ 0.15) ferrite has a single-spinel structure with FD-3 m space group. Additionally, by analyzing the XRD data, it is found that the lattice constant is the largest when Al 3+ is undoped. The range of lattice constant is (8.3751 ~ 8.3900) Å, the range of saturation magnetization ( M s ) is (68.77 ~ 79.39) emu/g, and the range of coercivity ( H c ) is (9.04 ~ 13.10) Oe. When the content of Al 3+ is 0.09, the permeability reaches the highest. In conclusion, the results obtained indicate that this ferrite is suitable for low-frequency electronic devices and also confirm that Fe 3+ was successfully replaced with Al 3+ . This paper provides a new idea for the study of spinel-structured ferrites by doping Al 3+ .
Submicrometer-sized LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM111) crystals with homogeneous composition are prepared via a polymer-chelation chemical solution process. The complexed chelate agents of ethylenediaminetetraacetic acid (EDTA) and polyethyleneimine (PEI) could chelate all metal ions in one step, with intimate mixing at the atomic level, ensuring a homogeneous ion distribution in the product. The as-prepared NCM111 crystals have a narrow particle size distribution with an average size of 250 nm, which can effectively shorten the lithium ion diffusion path. In addition, the NCM111 crystals majorly consist of electrochemically active {010} facets and low Li + /Ni 2+ cation mixing, thus delivering a high reversible discharge capacity of 156.1 mAh g −1 after 100th cycles and good rate capability of 102.7 mAh g −1 at 10 C. Furthermore, it is found that the induction of excess Li could deteriorate the rate capability and increase the Li + solid-state diffusion resistance. However, Al 3+ doping could effectively improve the cycling performance, while Nb 5+ doping could increase significantly the discharge capacity as well as rate capability. Owing to the flexibility of the chelating chemistry , the synthesis should be extended to prepare other multicomponent single-crystal cathodes with homogeneous composition and desired substation.
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