Upconversion emissions from lanthanide ions have unparalleled advantages in the field of temperature sensing and information encryption. Despite extensive research on temperature sensing probes, developing highly sensitive temperature measurement applications still poses a significant challenge. This study utilizes lanthanide ions doped BaTiO3 as the foundational material to develop a fiber optic probe with enhanced temperature sensitivity. The optical temperature-sensing capabilities are assessed based on the intensity ratio of various energy levels in BaTiO3: Yb/Tm/Er phosphors. Notably, the non-thermal coupling energy level between Tm and Er demonstrates the highest sensitivity, achieving a maximum relative sensitivity of 2.70% K--(1) at 303 K. By leveraging the temperature-dependent color change of the material, a large-capacity photonic barcode for temperature information storage and encrypted transmission is developed, thereby expanding the potential applications of temperature monitoring.

Addressing the water shortage issue in a green and sustainable manner, solar water evaporation technology is regarded as a promising strategy for water desalination. However, conventional solar evaporators face structural limitations and exhibit lower evaporation rates, hindering their practical application. In this study, we propose a biomimetic three-dimensional (3D) solar evaporator that demonstrates exceptional performance in light absorption and thermal management. By utilizing two-dimensional (2D) HF-free MXene nanosheets as photo-thermal materials, the evaporator enhances light capture, and the surface-rich functional groups of these nanosheets facilitate efficient water transport. Experimental results have shown that, by leveraging the advantages of the 3D structure, the evaporation rate of water under single solar irradiation can reach 3.46 kg m-2h-1, surpassing many other experimental devices. In addition to its environmental friendliness, the evaporator's edge salt crystallization provides excellent anti-salt deposition functionality. Furthermore, purification experiments on West Lake water were conducted, demonstrating its efficacy in water treatment. This innovative evaporator can be considered as a 3D sustainable seawater desalination strategy with potential application prospects.

The application prospects of ZnS stress luminescent materials cover many fields such as high‐precision structural monitoring, smart materials, biomedical imaging, and new sensor technologies, which bring broad application prospects and significance to them in the fields of engineering, medicine, and scientific research. In this article, the electronic structure and optical properties of ZnS materials are successfully regulated by applying pressure and doping rare earth metals (Re), and it is found that the regulation of the luminescence properties of ZnS is the result of stress and doping interactions. Specifically, when pressure is applied or Re metal doping, the lattice structure is deformed and the atomic spacing is adjusted, which affects the electronic energy level distribution and optical properties of ZnS materials. Computational analysis of density functional theory (DFT) reveals the microscopic mechanisms behind these changes, including changes in lattice parameters, adjustment of bond length, and changes in band structure. This study provides theoretical guidance for the design and synthesis of high‐performance and high‐stability ZnS light‐emitting materials, and is of great significance for expanding the application of ZnS in the field of lasers and sensors.

The conventional sea water desalination technologies are not yet adopted worldwide, especially in the third world countries due to their high capital cost as well as large energy requirement. To solve this issue in a sustainable way an interfacial solar water evaporation device is designed and proposed in this article using the branches of Prunus serrulata (PB). The PB has abundant microchannels and shows excellent photothermal conversion capability after carbonization. Moreover, the easy access to raw materials and the facile fabrication process makes the solar water evaporating device very cost effective for seawater desalination application. Experiments show that in the presence of the fabricated evaporator the evaporation rate of water can reach 3.5 kg m-2 h-1 under 1 sun, which is superior to many similar experimental devices. In addition, its advantages, such as effective sewage purification capability, low cost, and environmental friendliness, make this evaporator highly competitive in the extensive promotion of this technology and can be considered as a new sustainable solution for seawater desalination with great application potential and prospects. A solar evaporator based on hydrogel modified biomass material is fabricated. The carbonized branches are modified by polyvinyl alcohol. The device has an excellent evaporation rate of 3.5 kg m-2; h-1 and a solar steam efficiency of 98.5% under 1 sun illumination. image

Solar interfacial water evaporation technology has shown great promise for seawater desalination and wastewater treatment. However, the deposition of salt crystals on the evaporator surface restrains the evaporation rate, which will affect further development of this technology. In this work, a spherical polystyrene foam was utilized as the material support, the surface of which was coated with photothermal materials for evaporator fabrication. The employing of well-prepared black Ti4O7 as a photothermal coating greatly improve the sunlight absorption of the surface, and the mixing of sodium alginate can achieve a hydrophilic effect. This unique coordination not only increases the evaporation rate of the spherical evaporator (2.46 kg m(-2) h(-1)), but also performs well in water purification. The spherical design allows the evaporator to periodically clean the salt deposits on the evaporator surface through self-rotation, which provides a promising way to deal with the problem of salt deposition in evaporators in the future.

As an indispensable indicator in the development of optical components,laser-induced damage threshold(LIDT)is still the direction of research to improve the accuracy of its measurement results.In this paper,an optimal allocation method of damage test points based on Monte Carlo method is proposed to improve the accuracy of LIDT fitting results.According to the limited irradiation test area and irradiation spot size of the test sample,a nonlinear degenerate defect damage model is simulated,and the sensitivity analysis of the influence of test points change on the fitting LIDT results at different fluence levels is analyzed.Then,according to the setting parameters of damage model,a model is established to generate relevant damage data.The number of test points at each specified fluence level is changed by the control variable method,with the number of test points unchanged at the rest of the fluences.The Monte Carlo method is used to perform multiple simulation calculations on all damage data.The relationship curve between the standard deviation of the fitting results and the test points is drawn,so as to calculate the sensitivity of the corresponding test points to the standard deviation of the damage threshold fitting result.Finally,a more reasonable allocation of test points under each fluence is carried out with this sensitivity as the weight.The results show that the standard deviation of the fitting result of the sensitivity weight method is 0.272 J/cm2,which is about 31%lower than the standard deviation of 0.395 J/cm2 in the standard distribution method.

Developing two-dimensional (2D) materials as anode materials have been proved a promising approach to significantly improve the charge storage performances of alkali metal ion. Herein, we investigate mono-layered VN2 as an anode material in Li, Na and K ion batteries. Firstly, the high stability of 2D-VN2 has been demonstrated via calculating the phonon spectra. 2D-VN2 is capable of delivering high capacities of 678.8, 339.4 and 1357.6 mAh g-1 in Li+, K+ and Na+ storage, respectively. In addition, the metallic properties and corresponding high electrical conductivity and low diffusion barriers of 201.1 meV for Li atoms, 34.7 meV for K atoms and 84.1 meV for Na atoms on VN2 surface, indicating good capacity and the superior rate performances of alkali metal atoms migration on VN2. The calculated average voltage of Li, Na and K are respectively 0.81 V, 0.29 V and 0.77 V, suggesting a promising voltage behavior compared with other 2D materials.

Among all inorganic perovskite, CsPbI3 has the closest ideal bang gap for solar cells. However, the instability of metal halides hinders its commercial application. The doping of A-site organic cations might improve the stability of perovskite and also make the bandgap adjustable, thus enhance its photoelectric properties. In this paper, the structure stability, electronic structure and optical properties of CsPbI3 with five different organic cations (H3NNH2+, CH3NH3+, C3H6NH2+, CH3NH2CH3+, CH3CH2NH3+) partially alternative doping instead the A site cation have been studied by using the first principles within density functional theory. In order to get accurate description of the bandstructure information, different exchange-correlation functions, e. g. PBE, PBE + SOC and HSE were used to describe the calculated systems, our calculation results indicated that the PBE exchange-correlation function can describe the electronic properties of the systems very well in this paper. Formation energy calculation indicates that all the doping systems are thermally stable; and all the doped CsPbI3 show good tolerance factor according Goldschmidt rule. Among the five different doping systems, the bandgap of doped H3NNH2+ will decrease to 1.28 eV, while the bandstructure of other doped cations will widen the bandgap. The maximum bandgap increased to 1.65 eV with doping C3H6NH2+. However, all the band structures are mainly contributed by inorganic framework. The results suggest that the structure doped organic cations can be exited stably, and the band edge of the optical absorption spectrum will be redshifted. These properties can provide research ideas for the subsequent research of A-site doping organic cations.

: (3-Nitroanilinium) (18-crown) (PF 6 ) ( 1 ), which is an organic-inorganic hybrid containing one-dimensional chains of hydrogen-bonded supramolecular cations, was synthesized under slow evaporation conditions and subjected to di ff erential scanning calorimetry, temperature-dependent dielectric measurements, and variable-temperature single-crystal X-ray di ff raction analysis. These analyses revealed the occurrence of a reversible structural phase transition [ P 21 / n P 21 / c] at 223 K and a dielectric anomaly, which, based on the results of structural analysis and potential energy calculations, was attributed to the synergistic e ff ect between the pendulum-like motion of the nitro group in the supramolecular cation, (3-nitroanilinium)(18-crown), and the order-disorder motion of PF 6 − anions.

Organic Inorganic Hybrid Double Perovskite (OIHDP) (MA)2KBiCl6 is an alternative material greatly potential for CH3NH3PbCl3. We have made a report of the narrow and long pentahedral region of (MA)2KBiCl6, which is stably according to chemically potential calculation by the first principles method. It is also found that a deep acceptor defect VMA could be easily formed in such kind of (MA)2KBiCl6, leading to the tendency of intrinsic p-type conductivity. A deep donor defect BiMA is obviously suppressed under a Cl-rich growth environment, and a deep acceptor defect ClMA is more likely to be produced with Cl-poor conditions. These results indicate that an increased abundance of Cl elements is going firmly with a reduced generation of BiMA, while the subsequent situation is that defects in ClMA are easier to be made than those in VMA. A great richness of Cl is necessary for an achieved effect of the inhibited deep defect BiMA, only through which the degraded photoelectric performance caused by deep defects could be avoided. Moreover, combination with the former experimental results, we found that the richness of Cl (halide ion) is necessary for an achieved good performance of solar cell devices.

White light-emitting diodes (wLEDs) have been considered to be new-generation light sources due to their advantages such as energy-saving, environment-friendly and long lifetime, safety and reliability. Nevertheless, it is the core issue to improve the luminous efficacy of wLED and excavate lighting properties in depth. At present, the commercial way to produce wLEDs are combining a blue-chip with yellow phosphor material as YAG : Ce3+, and the luminescence efficiency of white LED can be effectively improved by improving the luminescence efficiency of phosphor. A novel nanocomposite powder of YAG : Ce3+ coated with anatase nanotitania particles was prepared by sol-gel method using tetrabutyl titanate as the precursor, and the effect of TiO2 nano-particles coating on the luminescence properties of YAG : Ce3+ phosphors were investigated. The phase structure and optical properties of the samples were characterized by X-ray diffractometer, scanning electron microscope and spectrometer. The results have revealed that TiO2 coating YAG : Ce3+ phosphors prepared at different temperatures and different volume ratios (TTBO : H2O) have a significant effect on the fluorescence spectrum of the powder, optimizing preparation temperature is 600 degrees C and TTBO H2O = 2:1 (in volume ratio). The result of the tests showed that TiO2 coating layer around the phosphor surface by the SEM observation, the diffraction peak of anatase is relatively strong, and the separation of the photogenerated e /h(+) pairs can be promoted, leading to increasing quantum efficiency. The Raman spectrum indicated that the energy of localized surface plasmon resonance (LSPR) propagating on the interface at the excitation wavelength of 633 nm, and the intensity of the characteristic peaks at 1 264. 10 and 1 283. 59 cm(-1) were increased. The photoluminescence spectrum indicated that luminescence intensity of TiO2 coating YAG : Ce3+ phosphors were improved 21%, the quantum efficiency has been improved 5. 5%, which was by the contribution of the TiO2 localized surface plasmon resonance effect. This study reveals that the localized plasmon effect based on TiO2 could effectively improve the luminescence efficiency of YAG : Ce3+ phosphor, and the application of YAG : Ce3+ phosphor to wLED plays an active role in high efficiency, high power and large lumen condition.

White light-emitting diodes (wLEDs) are one of most efficient and environmentally friendly lighting technologies, which are known as indispensable solid-state light sources. At present, the commercial way to produce wLEDs is combining a blue chip with yellow phosphor material as YAG: Ce3+. The luminous efficacy of the wLEDs could reach the ideal value, but the color rendering is poor, which could be ascribed to the lack of red component in the emission spectrum. Thus, the development of wLEDs is limited in the application of high-quality general lighting, such as showcase lighting, medical illumination and projection display. A promising deep red phosphor, Eu2+ doped CaAlSiN3 (CASN) was prepared by high temperature solid reaction in a gas pressure sintering furnace. In this work, luminescent properties, crystal structure of the CASN were investigated via X-ray diffraction (XRD) and photoluminescence spectra (PL), by applying the structure and bandgap engineering strategies, we have revealed the essential energy transfer mechanism of its luminescence phenomenon. The XRD results indicate that the sample is well-crystallized in the combustion procedure, and its crystal structure has not changed when doped with low concentrations of rare-earth ions. Ca-0.992 AlSiN3 : 0. 008Eu(2+) phosphors could be effectively excited by a broad emission spectrum extending from 200 to 600 nm, and this broad excitation band could be deconvoluted into five sub-bands by Gaussian fitting. A substantial red spectra is centered at 650 nm under the 450 nrn excitation, with a wide broad full width at half maximum (FWHM) of the emission spectrum(91. 4 nm) , due to the electron transfer of Eu2+ from 5d to 4f. The band structure calculation shows that Ca-0.9375 AlSiN3 : 0. 062 5Eu(2+) has an indirect band gap with an energy gap of about 3. 14 eV, with the atomic projected Ca-3p, Eu-3d, N-2p, Al-3p, Si-3p states. An optimal spectral model was designed to guide packaging of the phosphor-converted wLEDs, and the influence of the various combination of Ca-0.992 AlSiN3 : 0. 008Eu(2+) phosphors was studied with the wLED packaging. A super wLED was attained by combining red Ca-0.992 AlSiN3 :0.008Eu(2+) phosphor and green beta-sialon phosphor with a blue LED chip, showing a high color rendering index of 92. 1, a high luminous efficacy of 101 lm . W-1, and a warm color temperature of 3 464 K. The phosphor of Ca-0.992 AlSiN3 : 0. 008Eu(2+) is effective to improve color rendering indexes for wLEDs with the contribution of its red spectral part with simultaneous spectral broadening, meanwhile it is of great value in luminous efficacy, color temperature and stability, which means that it is a promising candidate for the red phosphor material for wLEDs.

Recently, more and more attention has been given to a semiconductor oxide-based surface-enhanced Raman spectroscopy substrate for its great stability and biocompatibility. However, its poor SERS sensitivity limits the applications of semiconductor oxide SERS substrates. In this paper, we provide a facile reduction method to modulate oxygen vacancy concentrations in oxide SERS substrates. Using MoO2 as an example, the resonance coupling as well as charge transfer between the semiconductor oxide SERS substrate and the target molecules were promoted for the reason of artificial oxygen vacancy embodied in the Raman signals being improved. By using the TEM, SEM, and XPS measurements, we confirmed that we successfully prepared defective MoO2- x with a polycrystalline surface. MoO2- x modulated oxygen vacancy treated with 6 wt % Li shows a very high detection sensitivity of 10-8 M (4.79 ug/L) for R6G, and the intensity of the Raman signal was highly enhanced. Because of the existence of defective energy levels, resonance coupling, as well as charge transfer between semiconductor and molecules, was obviously promoted. More importantly, the method of modulating oxygen vacancy can be widely used in semiconductor oxide materials for its chemical enhancement capacity can be promoted by artificial oxygen vacancy.

In order to enhance the fluorescence intensity and reliability of CdS nanoparticles, synthesis, fluorescence property of CdS by different mass ratio of Cd to S, and influence of stabilizer were studied. CdS/ZnO composite structures were synthesized in alkaline condition using the hydrothermal synthesis method. In addition, all samples were tested by XRD, fluorescence spectroscopy and SEM. The results showed that CdS nanoparticles and CdS/ZnO composite nanoparticles were single and relatively pure. ZnO coated on the surface of CdS. Under the 328.5 nm ultraviolet excitation, emission spectrum was narrow and symmetrical, and the emission peak was at 463 nm. The fluorescence intensity of CdS/ZnO composite structure nanoparticles increased obviously. The best mass ratio of CdS to ZnO was 1 1, whose fluorescence efficiency was 11% higher than that of CdS nanoparticles. The results of first principle study indicated that the energy band of Cd-4d, S-3p and Cd-5s were comprised of 5, 3 and 1 energy levels, respectively, in the band structure of CdS. By comparing partial density of states in different orbits, it can be seen that the boundary of conduction band was mainly comprised of Cd-5s orbit, the boundary of valence band was mainly comprised of S-3p orbit, and the electronic states near 7 eV was mainly comprised of Cd-4d orbit. In the band structure of ZnO, valence band on top was mainly comprised of O-2p electron, the region near Fermi level was mainly comprised of Zn-3d electron, conduction band was mainly comprised of Zn-3d and O-2p electron. In CdS/ZnO composite structures, energy levels of Zn-3d electron were near energy levels of S-3p electron and presented a type-II band structure, thus narrowing band-gap. The electron transition became easier, depressing the recombination of electrons and holes, and improving the efficiency of fluorescence.

利用碳热还原法制备了LaSi 3 N 5 ∶Ce 3+ 蓝色荧光粉,重点研究了原料中掺C量和退火对样品纯度及发光性能的影响。通过X射线衍射仪和荧光光谱仪分别表征样品的晶体结构和发光性能。研究结果表明:1 600℃时能够合成主相为LaSi 3 N 5 ∶Ce 3+ 的荧光粉。在360nm紫外光激发下样品可获得波段范围在380~600nm的单峰宽带发射谱,归结于Ce 3+ 的5d-4f的能级跃迁。当n C /n La =4/1时样品发光强度达到最大,并且光谱出现先红移后蓝移的现象。经过退火的样品的发光强度与退火前相比提高了60%~345%。将热处理后的n C /n La =4/1的样品与商用YAG混合涂覆在UV芯片上(λ em =365nm)封装成WLED,证实了LaSi 3 N 5 ∶Ce 3+ 在白光LED领域潜在的应用价值。

The influence of vacancy defect on the doping of silicon nanowires is systematically studied by the first-principles calculations. The atomic structures and electronic properties of vacancies and vacancy—boron (vacancy—phosphor) complexes in H-passivated silicon nanowire with a diameter of 2.3 nm are explored. The results of geometry optimization indicate that a central vacancy can exist stably, while the vacancy at the edge of the nanowire undergoes a local surface reconstruction, which results in the extradition of the vacancy out of the nanowire. Total-energy calculations indicate that the central vacancy tends to form a vacancy—dopant defect pair. Further analysis shows that n-type doping efficiency is strongly inhibited by the unintentional vacancy defect. In contrast, the vacancy defect has little effect on p-type doping. Our results suggest that the vacancy defect should be avoided during the growth and the fabrication of devices.

In order to obtain higher detection rate and faster training speed for image steganalysis,a new steganalysis algorithm based on extreme learning machine(ELM)was presented by combining with the single hidden layer feedforward neural networks(SLFN).Firstly,some features in discrete cosine transform(DCT) and spatial domain were extracted from a JPEG image according to Fridrichs algorithm.Then the original 193-dimensional features were reduced to 18-dimensional features with PCA.Finally,A blindly steganalysis algorithm was constructed with the classifying technique of ELM.The experimental results showed that ELM had faster learning speed and similar classification accuracy compared with SVM since it had a smaller number of turning parameters and less number of neurons.ELM can therefore be used in a blind steganalysis for all kinds of JPEG images.

A novel broadband emission phosphor Sr(3-2x) Li(1+ x) MgV3 O12 : xEu3+ was synthesized by a solid-state reaction method. Then discussed the luminous property under the influence of temperature and doping density of Eu3+, was discussed. X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence spectra were used to characterize the feature of Sr(3-2x)Li(1+x)MgV3O12 : xEu3+. The excitation and emission spectra exhibit that the phosphor of Sr(3-2x) Li(1 + x) MgV3O12 : xEu3+ matches with nearly ultraviolet chip. The emission band covers from 450 to 630 nm, which shows that the phosphor is promising single-phase phosphors for white LED.

The SrMgAl10O17:Eu2+ and SrMgAl10O17:Eu2+, Er3+ blue phosphors were synthesized by the combustion synthesis method. Their crystal structures and luminescent properties were analyzed by X-ray diffraction (XRD)、scanning electron microscope (SEM) and photoluminescence spectra, respectively. The XRD and SEM results indicate that the sample is well-crystallized in the combustion procedure, and its crystal structure has not changed when doped with low concentrations of rare-earth ions. PL results show that the phosphor of SrMgAl10O17:Eu2+can be effectively excited by near UV LED chip with a broad emission spectrum extending from 430 nm to 520 nm, and has main peaks located at 460nm. Furthermore, the sample of the luminous intensity is the largest when the Er2+, Er3+co-doped concentration is 4%, and the emission intensity of Sr0.95MgAl10O17:0.05Eu2+, Er3+phosphor is significantly enhanced 54.9%higher than that of SrMgAl10O17:Eu2+phosphor. It is indicated that Er3+has good sensitization effect for Eu2+in luminescence, and this can be explained by the theory of energy transfer.

Based on first principle FP-LAPW calculations, the electronic structure and magnetic properties of ZnO with Zn cation vacancy has been investigated. We find that the cation vacancy defect can induce a magnetic moment of about 2μB/supercell. The magnetic moment mainly comes from 2p-orbitals of O atoms which surround the Zn vacancy. We also find that the two Zn vacancies in ZnO always coupled Ferro-magnetically. Furthermore, the system shows half metallic Ferro-magnetic properties with high Curie temperature.