The spinel?phase Zn₂Ga_2.98-x Ge_0.75O₈:Cr_0.02, La _x (x=0.005,0.010,0.015,0.020,0.025) nanoparticles were synthesized by a hydrothermal method in combination with a subsequent heat treatment. With the La³⁺ doping concentration increasing from 0 to 0.025, the average particle size of these nanoparticls increased from 64 nm to 78 nm. Under 590 nm excitation, La³⁺?doped ZGGO nanoparticles exhibited stronger narrow?band NIR emission peaked at 697 nm, originating from the ²E(²G)→⁴A₂(⁴F) transition of Cr³⁺. From the TEM and emission spectral analyses, it can be found that the increased NIR persistent luminescence is attributed to the increased particle size and the increased number of luminescent centers in a relatively strong crystal field environment. On the basis of thermoluminescence spectra and the afterglow decay curves, it can be found that La³⁺ doping leads to the formation of more traps related to the thermal activation process and the afterglow time exceeding 15 h.

In this study, the optical properties of 3D carbon ball were theoretically investigated by using Density?Functional Theory (DFT) and wave function analysis. The electron?leaping mechanism in the Ultraviolet?visible (UV?vis) absorption spectrum was investigated. The electronic excitation properties of 3D carbon ball were investigated by Transition Density Matrix (TDM) and Charge Density Difference (CDD). Raman spectra were calculated and the vibrational modes of the 3D carbon ball were further explained. Meanwhile, the interaction between 3D carbon ball and the external environment was investigated using Electrostatic Potential (ESP), and the degree of electron delocalization of 3D carbon ball was investigated based on the magnetic induction current under the applied magnetic field.It is shown that the absorption spectra of three?dimensional carbon spheres are mainly in the ultraviolet region and that they have a strong electron delocalization capability. This study can provide a theoretical basis for the application of other 3D π?conjugated molecular structures in linear and nonlinear optics.

In order to better deal with the oily sludge produced in the process of oil production, gathering and transportation as well as oil refining, and in line with the current development trend of environment⁃friendly chemicals in the petrochemical industry, it is very important to use environmentally friendly and low toxic and non⁃toxic chemical reagents in the neighborhood of sewage treatment. This paper introduces a new cleaning agent for oil sludge. Compared with the traditional cleaning agent, the new cleaning agent uses natural chemical derivatives (environmental friendly plant solvent is the main component), which has the characteristics of low toxicity, low pollution and high cleaning efficiency. The use temperature is 5~10 ℃ lower than the field use temperature, further reducing the use of energy. Under the synergism of composite cleaning agent, the residual oil rate in the cleaned sludge can be less than 2%, which has a wide and excellent application prospect.