ABSTRACT
High-performance soft magnetic materials are important for energy conservation and emission reduction. One challenge is achieving a combination of reliable temperature stability, high resistivity, high Curie temperature, and high saturation magnetization in a single material, which often comes at the expense of intrinsic coercivity-a typical trade-off in the family of soft magnetic materials with homogeneous microstructures. Herein, a nanostructured FeCoNiSiAl complex concentrated alloy is developed through a hierarchical structure strategy. This alloy exhibits superior soft magnetic properties up to 897 K, maintaining an ultra-low intrinsic coercivity (13.6 A m-1 at 297 K) over a wide temperature range, a high resistivity (138.08 µΩ cm-1 at 297 K) and the saturation magnetization with only a 16.7% attenuation at 897 K. These unusual property combinations are attributed to the dual-magnetic-state nature with exchange softening due to continuous crystal ordering fluctuations at the atomic scale. By deliberately controlling the microstructure, the comprehensive performance of the alloy can be tuned and controlled. The research provides valuable guidance for the development of soft magnetic materials for high-temperature applications and expands the potential applications of related functional materials in the field of sustainable energy.
ABSTRACT
High-entropy oxides (HEOs), a class of compounds that include five or more elemental species, have gained increasing attraction for their capability of optimizing the target properties. To date, even though some high-entropy oxides have been successfully prepared, their applications still need to be explored. In the present study, a lithium-manipulation strategy for constructing transition metal oxides (LTM) via a modified solid-state method was investigated. The as-synthesized LTM contained six highly dispersed metal species (Li, Fe, Co, Ni, Cu, Zn) and demonstrated a rocksalt-type structure. Besides, with the introduction of Li, more oxygen vacancies were produced which was also accompanied by shrinking of the lattice constant. When the molar ratio of Li was equal to the other TM cations (LTM16.7), the electrical conductivity was greatly enhanced by a factor of 10 times. Moreover, LTM16.7 achieved the best HER (η = 207 mV at 10 mA cm-2) and OER performances (η = 347 mV at 10 mA cm-2) with elevated electrical conductivity. To facilitate further design of this new kind of materials, we also conducted DFT calculations and elemental alternation experiments, which showed that Fe acted as electrocatalytic sites in this HEOs system. This Li-incorporation strategy opens a new way to understand and modify defect-related HEOs.
ABSTRACT
To increase the utilization ratio and catalytic efficiency of the nano TiO2, The RGO/TiO2/(Ag) powders and RGO/TiO2/Ag aerogel photocatalyst were designed and prepared. The composition and microstructure of RGO/TiO2/(Ag) powders and RGO/TiO2/Ag aerogel were studied, in addition, the photocatalytic activity of RGO/TiO2/(Ag) powders and RGO/TiO2/Ag aerogel was researched by the photocatalytic degradation behavior of formaldehyde solution and formaldehyde gas respectively. The result indicate that TiO2 is uniformly loaded on the surface of RGO with a particle size of 10 nm to 20 nm. When the amount of graphene oxide added is 1 wt%, RGO/TiO2 powder has the highest degradation effect on formaldehyde solution, in addition, the introduction of Ag can greatly improve the photocatalytic effect of the sample. The results also show that the pore size of RGO/TiO2/Ag aerogel is between 7.6 nm and 12.1 nm, and the degradation rate of formaldehyde gas is 77.08% within 2 hours.
ABSTRACT
Bi3+, Eu3+, Dy3+ activated Y2O3 phosphors were prepared through the sol-gel process. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, and photoluminescence (PL) spectra were used to characterize the resulting phosphors. The XRD patterns show the refined crystal structure of Y2O3. The energy transfer processes of Bi(3+)-Eu3+ occurred in the host lattices. The thermal stability of Y2O3:Bi3+, Eu3+, Dy3+ phosphors was studied. Under short wavelength UV excitation, the phosphors show excellent characteristic red, blue, and yellow emission with medium intensity.
ABSTRACT
CdSe quatum dots (QDs) have been prepared through the one-pot process. Ultraviolet-visible (UV-vis) absorption and emission spectra were used to characterize the resulting samples. The effect of the synthesis time and temperature on the optical properties of the CdSe QDs samples have been studied. The maximum of the absorption spectra of the CdSe QDs samples is 486 nm and the emission spectra is 528 nm. The emission intensity of the CdSe QDs samples increases, and the emission maximum presents a red shift with increasing reaction time.
ABSTRACT
LaMgAl11O19, is a kind of rare earth aluminate with the hexagonal structure, which has been used as a host material for the luminescence of various rare earth and magnet-like ions. LaMgAl11O19:Eu3+ phosphors have been prepared through the one-pot method. X-ray diffraction (XRD), thermogravimetric and differential thermal analysis (TG-DTA) and photoluminescence spectra were used to characterize the resulting phosphors. The results of XRD indicated that the phosphors crystallized completely at 1,400 degrees C. In LaMgAl11O19:Eu3+ phosphors, the Eu3+ shows its characteristic red emission at 615 nm (5D0-7F2) upon excitation into 404 nm, with an optimum doping concentration of 15 mol% of La3+ in the host lattices.
