Min Liu

Ce-doped gadolinium gallium aluminum oxide (Ce: GGAG) precursors were first prepared by the microwave-assisted homogeneous precipitation method (MAHP). Thermal gravity-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), specific surface area analysis (BET) and field emission scanning electron microscopy (FE-SEM) were employed to investigate the crystal structure, phase evolution and morphologies of the Ce: GGAG precursors and powders. The influence of Ga ion concentration in the salt solution on the properties of Ce: GGAG powders was investigated. All the precursors were transformed into single-phase GGAG after being calcined at 950 °C in a furnace for 3 h. Monodispersed Ce: GGAG powders were obtained as the Ga ion concentration was lower than 0.06 mol/L. Single-phase and dense Ce: GGAG ceramics were obtained after sintering at 1600 °C in a flowing oxygen atmosphere for 10 h. Specifically, the Ce: GGAG ceramic reached its maximum density of ~6.68 g/cm³, which was close to its theoretical density of 6.70 g/cm³, and exhibited the highest optical transmittance of 65.2% at 800 nm after hot isostatic pressing sintering (HIP) as the Ga ion concentration was 0.02 mol/L. The decay time and light yield of the GGAG ceramic were 35 ns and 35,000 ± 1250 ph/MeV, respectively, suggesting that Ce: GGAG ceramics prepared using MAHP-synthesized nanopowders are promising for scintillation applications.

Ultrathin porous Co₃O₄ nanosheets are synthesized successfully, the thickness of which is about three unit-cell dimensions. The enhanced oxygen evolution reaction (OER) performance and electronic interaction between Co₃O₄ and Au is firstly reported in Co₃O₄ ultrathin porous nanosheets by physically mixing with Au nanoparticles. With the loading of the Au nanoparticles, the current density of ultrathin porous Co₃O₄ nanosheets is enhanced from 9.97 to 14.76 mA cm⁻² at an overpotential of 0.5 V, and the overpotential required for 10 mA cm⁻² decreases from 0.51 to 0.46 V, smaller than that of commercial IrO₂ (0.54 V). Furthermore, a smaller Tafel slope and excellent durability are also obtained. Raman spectra, XPS measurement, and X-ray absorption near edge structure spectra (XANES) show that the enhanced OER ascribed to a higher Co²⁺/Co³⁺ ratio and quicker charge transfer due to the electronic interaction between Au and ultrathin Co₃O₄ nanosheets with low-coordinated surface, and Co²⁺ ions are beneficial for the formation of CoOOH active sites.

Lanthanide-doped upconversion nanoparticles have attracted extensive research interest due to their promising applications in various fields.

Li⁺ doping is a well-known, simple, yet efficient strategy to optimize the properties of upconverting materials.

Modification of Bi₆Fe_1.9Co_0.1Ti₃O₁₈/SiO₂/NaGdF₄:Yb³⁺,Er³⁺ nanocomposites with different SiO₂ thickness for tunable upconversion emission and ferromagnetic properties.

Bi₆Fe_1.9Co_0.1Ti₃O₁₈ (BFCTO)/NaGdF₄:Yb³⁺, Er³⁺ (NGF) nanohybrids were successively synthesized by the hydrothermal process followed by anassembly method, and BFCTO-1.0/NGF nanosheets, BFCTO-1.5/NGF nanoplates and BFCTO-2.0/NGF truncated tetragonal bipyramids were obtained when 1.0, 1.5 and 2.0 M NaOH were adopted, respectively. Under the irradiation of 980 nm light, all the BFCTO samples exhibited no activity in degrading Rhodamine B (RhB). In contrast, with the loading of NGF upconversion nanoparticles, all the BFCTO/NGF samples exhibited extended near-infrared photoactivity, with BFCTO-1.5/NGF showing the best photocatalytic activity, which could be attributed to the effect of {001} and {117} crystal facets with the optimal ratio. In addition, the ferromagnetic properties of the BFCTO/NGF samples indicated their potential as novel, recyclable and efficient near-infrared (NIR) light-driven photocatalysts.

Morphology control of layered Bi ₁₁ Fe _2.8 Co _0.2 Ti ₆ O ₃₃ microcrystals: critical role of NaOH concentration and citric acid.