宿州学院

A series of red phosphors CaMo1-xO4:xEu3+(x=0.001,0.005,0.01,0.015,0.02,0.03,0.04,0.05,0.06,0.07,0.08,0.09,0.10)were synthesized by hydrothermal method.Techniques such as X-ray powder diffraction(XRD),scanning electron microscopy(SEM)and photoluminescence(PL)spectra were used to characterized the samples.The effects of different experimental conditions on the luminescent properties were systematically investigated.The results shows that the synthesized CaMo1-xO4:xEu3+samples are pristine tetragonal structure.Under 394.6 nm excitation,the emis-sion peaks of samples are at 592 nm,614 nm,654 nm and 701nm,which correspond to 5D0→7F1,5D0→7F2,5D0→7F3 and 5D0→7F4 transition of Eu3+ions,respectively.The transition intensity reaches its maximum at 614 nm,and the phosphor emits red light.The optimal doping amount of Eu3+ions is 0.05,and fluorescence quenching is caused by exchange interac-tion.The emission intensity decreased with the increasing of temperature.When the temperature increases to 453 K,the lumi-nescence intensity of the sample is 54％of that at 303 K.And the activation energy of CaMo0.95O4:0.05Eu3+was calculated to be 0.262 eV through fitting the curves of ln(Io/I-1)～1/kT.The samples are located red region on the CIE 1931 chroma-ticity diagram,indicating that they potential single-doped red luminescent materials for LEDs.

Aiming at the problem of determining the drought-limited water level of emergency drought-resistant backup reservoirs,a model for determining the drought-limited water level was established based on the principle of wide and shallow damage with the goal of minimizing the time period average water shortage rate and the number of time periods with severe water shortage.A method and operational rules for determining the drought-limited water level of emergency drought-resistant backup reservoirs under extreme drought conditions were proposed.The proposed method was applied to the Deze Reservoir,a backup water source for Kunming City,and the degree of water supply guarantee under different schemes.The results indicate that the method can realize the optimal design of phased drought-limited water level in emergency drought-resistant backup reservoirs,and effectively reduce the adverse impact of extreme drought on socio-economic water use.By setting the drought-limited water level of the Deze Reservoir,the number of months with severe water shortage for emergency water supply in Kunming City can be reduced from 229 to 34,and the average monthly water shortage rate can be reduced from 27.58％to 12.74％,thereby mitigating the occurrence of extreme water shortages.Under extreme drought conditions,the combined use of the drought-limited water level and dead storage capacity can further significantly enhance the level of water supply guarantee,reducing the number of months with severe water shortages to 21 and the average monthly water shortage rate to 2.52％.

The increase of mining depth and the large-scale mining of coal seam are affecting the structure of underground water sys-tem in mining area.The study of chemical characteristics of underground water and its evolution law is of great significance to the safe mining of coal mine.Taking different aquifers groundwater of Yangliu Coal Mine in Huaibei Mining area of Anhui province as the research object,this paper systematically analyzes the chemical characteristics and evolution mechanism of groundwater in Yangliu Coal Mine by means of mathematical statistical analysis and Piper three-line graph.The results show that,the aquifers in the study area are weakly alkaline as a whole,the fourth aquifer of Cenozoic is dominated by Na++K+and SO42-,the fractured sandstone aquifer of Permian is mainly controlled by Na++K+and HCO3-,and the major affecting ions in the Taiyuan Formation and Ordovi-cian limestone aquifers are Ca2+and SO42-.There are some differences in hydrochemical types among these aquifers.SO4·HCO3-Na·Ca and HCO3-Na·Ca types dominate the fourth aquifer Cenozoic,HCO3·Cl-Na type dominates the sandstone fissure aquifer,and SO4-Mg·Ca·Na type dominates the Taiyuan Formation 1-4 ash aquifers.The Ordovician limestone aquifer is dominated by SO4-Ca·Mg type and SO4·HCO3-Ca·Mg type.Each aquifer in the mining area is mainly affected by rock weathering and evapora-tion and concentration.Salt rock and silicate karst in the water are deconstructed into the main source of Na++K+,and sulfate and car-bonate karst hydrolysis are the main sources of Ca2+and Mg2+.Besides carbonate dissolution,HCO3-is also controlled by desulphur-ization acid.SO42-is mainly derived from sulfate dissolution and pyrite oxidation.The leaching and human activities contribute more to the chemical composition of groundwater.

This study investigates the interfacial adhesion enhancement mechanisms of TiAlN coatings deposited on nitrocarburized 300M ultra-high-strength steel substrates.Through radio frequency(RF)magnetron sputtering technology,TiAlN coatings(approximately 4 μm thick)are fabricated on both pristine and plasma-nitrocarburized(PNC)substrates.Comparative analyses of phase composition,microstructure,and mechanical properties are conducted using field emission scanning electron microscope(FESEM),X-ray diffraction(XRD),nanoindentation,and scratch testing.Molecular dynamics(MD)simulations with Materials Studio(MS)software elucidate atomic-scale interactions between TiAlN coatings and substrates.Results demonstrate that the PNC pretreatment generates a dual-phase structure(about 65 μm thick)comprising the γ-Fe4N compound layer and a high-hardness diffusion layer,establishing a continuous hardness gradient at the coating-substrate interface.The PNC/TiAlN composite coating exhibits enhanced interfacial adhesion strength,attributed to mechanical interlocking from plasma-etched microvoids and optimized lattice matching.Scratch tests reveal a significant increase in critical load to 60 N for coating delamination in PNC/TiAlN systems compared with monolayer coatings.These improvements mitigate brittle spallation risks while maintaining superior hardness(29.26 GPa)and wear resistance.This paper provides atomic-level insights into adhesion enhancement mechanisms and proposes a viable duplex surface engineering strategy for high-strength steel components.

40K,as a possible source of radioactive heat in the Earth's core,is crucial for the Earth's evolution,and the behavior of K between metal/sulfide and silicate phases in the Earth's core-mantle differentiation process has an important impact on the K content of the Earth's core.In this paper,the high-temperature and high-pressure experiments of the EH4 chondrite compositions were conducted under conditions of 1220-1400 ℃ at 0.5 GPa,and water contents of 0-5 wt％,in order to investigate the influences of water contents on the partitioning of K between the metal/sulfide and silicate phases as well as on those phase contents in the core-mantle differentiation process of magma ocean.Preliminary results show that the presence of water has significant effects on the partitioning of K between metal/sulfide and silicate phases and contents of those phases in the Earth's core-mantle differentiation process of magma ocean.The addition of water in the magma ocean may limit the percentage of core segregation during the Earth's core-mantle differentiation,but appropriate water content(2 wt％)of the magma ocean could result in the increased proportion of sulfide phase and the increased total amount of K in the Earth's core.The partition coefficients of K between metal and silicate phases as well as between sulfide and silicate phases under anhydrous conditions are all lower than those under hydrous conditions,with the obtained highest partition coefficients of K under hydrous condition of 2 wt％water.Based on the experimental results,it can be seen that contents of K in the differentiated Earth's core under hydrous condition of 2 wt％water are roughly 1.74-5.40 times of that in the differentiated core under anhydrous condition.