Study of the Electronic Structure and Optical Properties of Rare Earth Luminescent Materials

Rare earth luminescent materials have attracted significant attention due to their wide-ranging applications in the field of optoelectronics. This study aims to delve into the electronic structure and optical properties of rare earth luminescent materials, with the goal of uncovering their importance in luminescence mechanisms and applications. Through theoretical calculations and experimental methods, we conducted in-depth analyses on materials composed of various rare earth elements. Regarding electronic structure, we utilized computational techniques such as density functional theory to investigate the band structure, valence state distribution, and electronic density of states of rare earth luminescent materials. The results indicate that the electronic structural differences among different rare earth elements notably influence their luminescence performance, providing crucial clues for explaining the luminescence mechanism. In terms of optical properties, we systematically examined the material’s optical behaviors through fluorescence spectroscopy, absorption spectroscopy, and other experimental approaches. We found that rare earth luminescent materials exhibit distinct absorption and emission characteristics at different wavelengths, closely related to the transition processes of their electronic energy levels. Furthermore, we studied the influence of varying doping concentrations and impurities on the material’s optical properties. Experimental outcomes reveal that appropriate doping can effectively regulate the emission intensity and wavelength, offering greater possibilities for material applications. In summary, this study comprehensively analyzed the electronic structure and optical properties of rare earth luminescent materials, providing deep insights into understanding their luminescence mechanisms and potential value in optoelectronic applications. In the future, these research findings will serve as crucial references for the technological advancement in fields such as LEDs, lasers, and bioimaging.

Intercalation Assembly, Characterization and Luminescent Properties of Novel Supramolecular Composite Materials, Tb(Ⅲ) Complex with Tetrapodal Ligand-Montmorillonite

Two kinds of Tb（ Ⅲ ） complexes with tetrapodal ligand, [TbL（NO3）]^3＋ and [TbL]^3＋ （L： 1,1, 1＇, 1＇-tera （ 2-pyridinecarboxylester ）-di （ trimethylpropane）） were intercalated into the interlayer space of montmorillonite （MT） by ion exchange and coordination reaction of L with the Tb^3＋ ion existing in the interlayer space of Tb-MT respectively. The obtained luminescent supramolecular composite materials, [ TbL （NO3） ]^2＋-MT and [TbL]^3＋-MT were characterized by elemental analysis, XRD, FT-IR, UV-vis and thermal analysis. At the same time, the luminescent properties of the materials were also studied. The results show that the intercalated materials with regular layered structure, good thermal stability and the interlayer spacing （d001） approximates to the size of the complex ions which are located in the interlayer space of MT in the form of a monolayer.

Preparation, Characterization and Luminescent Properties of MCM-41 Type Materials Impregnated with Rare Earth Complex

Hybrid materials incorporating Eu-(TTA)3·2H20 (hereafter designated as Eu-TTA, with TTA: thenoyltrifluoroacetone) in unmodified or modified MCM-41 by 3-aminopropyl-triethoxysilane (APTES) were prepared by impregnation method. The obtained materials were characterized using X-ray diffraction (XRD), IR and diffuse reflectance spectroscopy and luminescence spectra. All the hybrid samples exhibited the characteristic emission bands of Eu3+ under UV light exci-tation at room temperature, and the excitation spectra showed significant blue-shifts compared to the pure rare-earth complex. Although the red emission intensity in the modified hybrid was almost the half of the red emission intensity in the pure Eu-TTA complex at room temperature, the hybrid showed a much higher thermal stability due to the shielding character of the MCM-41 host.

Modular Design Using Sustainable Luminescent Materials in Energy-Saving Reflective Cat’s Eyes for Public Road Safety Planning

Recently,there has been a global movement toward environmental protection and energy conservation through the design and development of new products in accordance with sustainable utilisation.In this study,rare earth luminescent materials were used owing to their active light emission and reusability.Additionally,solar lightemitting diode lights and car-light reflection were utilised to increase the recognition and reliability of reflective cat eyes.Along with carbon reduction,this can save energy and enhance road safety.This study considered the Theory of Inventive Problem Solving and a literature review to analyse the issues in existing products.Then,expert interviews were conducted to screen projects and develop product design policies.Finally,the ratio of light-storage materials was experimentally determined and the prototypes implemented.This cat’s eye addresses the shortcomings identified in previous analyses of existing products.We applied energy storage environmental protection materials,together with material proportioning(which balanced warning efficiency against cost-effectiveness)to develop diversified modular kits;these were flexible in terms of quantity and easily assembled.This study achieved four key objectives:(1)reducing the research and development costs of the manufacturer;(2)offering buyers a diverse suite of products;(3)responding to a need to improve diverse road user safety;and(4)reducing government procurement costs for safety warning products.The results provide a reference for the creative modular design of energy-saving products for public road safety planning in various industries.

Online and Offline Hybrid Teaching in the Luminescent Materials and Applications Course

Due to the outbreak of |x-19,colleges and universities have actively responded to the call of the state to carry out online teaching in completing their teaching tasks.After the epidemic,the online and offline hybrid teaching has become a novel mode of teaching which meets the requirements of teaching reform and the information society.This teaching method integrates both the online and offline teaching which plays an important role in enhancing teaching qualities and learning experiences.However,due to the lack of experience,there are some issues occurring in the teaching process of this method.The Luminescent Materials and Applications course is used as the subject in this article.The difficulties in traditional offline teaching as well as the advantages,detailed course construction process,and effectiveness evaluation of hybrid teaching are summarized and meticulously analyzed.In regard to that,the application of the online and offline hybrid teaching in the Luminescent Materials and Applications course is beneficial to the learning of professional knowledge and the cultivation of students'scientific literacy.Therefore,it is an effective way to improve and enrich this course by using the online and offline hybrid teaching method.

Effects of SrO/Al_2O_3 Molar Ratio on the Luminescent Characteristics of Rare-Earth Strontium Aluminate Phosphors

The study on the effects of SrO/Al 2O 3 molar ratio on the crystalline phases and photoluminescence characteristics of strontium aluminate phosphors co-activated with Eu 2+ and Dy 3+ were conducted by X-ray powder diffractometry, fluorescence spectrometer and photometer. The strontium aluminate luminescent materials with different SrO/Al 2O 3 molar ratio emit the visible lights with different color tone after removal of excitation. The peak wavelengths of the emission spectra drift in the direction of short wave, the quantity of Sr 4Al 14O 25 crystalline phase increases and the afterglow time lengthens with the SrO/Al 2O 3 reduction. The results show that when the SrO/Al 2O 3 molar ratio is near 1, the photoluminescence materials have high luminescent intensity, and when it is near 0.75, they have long afterglow time. However, when SrO/Al 2O 3 molar ratio is more than 1, the luminescent materials appear strong alkaline in water solution; when SrO/Al 2O 3 molar ratio is much less than 0.75, the samples need a higher temperature to be sintered.

Comparison study of two aldehyde group finishing agents in surface modification of up-conversion luminescence materials

Surface modification of up-conversion luminescence materials （Na[Y0.57Yb0.39Er0.04]F4 modified by amino groups） by grafting and modifying with aldehyde groups was studied by means of Fourier transform infrared spectroscopy （FTIR）, scanning electron microscopy （SEM）, thermogravimetric analysis （TGA）, and emission spectrum （EM）. The surface modification effect was compared using two different finishhag agents, p-phthalaldehyde and glutaraldehyde. It was found that the surface of up-conversion luminescence materials could be modified by aldehyde groups of the two finishing agents, the systematic dispersibility and the thermostability of the up-conversion luminescence material modified by p-phthalaldehyde were better than those of the material modified by glutaraldehyde, and the luminous intensity of the material modified by p-phthalaldehyde was increased. The AI （the ratio of the suspended segmental quality in the specimen to the total mass of the specimen） of the material modified by p-phthalaldehyde was higher than that of the material modified by glutaraldehyde. It is obviously seen that the embellishment effect of p-phthalaldehyde as a finishing agent was better than that of glutaraldehyde. In addition, the reasons why p-phthalaldehyde is a good finishing agent are also explained.

Synthesis and Properties of Luminescent Material La_2O_2CO_3

A novel rare earth luminescent material La2O2CO3 was synthesized successfully by sintering the mixture of La2(CO3)3 and KCl powders. The XRD results revealed that the additive KCl not only affected the crystal form and crystallinity of the final product, but also greatly promoted its luminescence, compared with the products without adding KCl. The as-prepared material showed a strong green emission band centered at 470 nm under the excitation of 325 nm. Our experimental results indicated that the crystal form of La2O2CO3 affected its luminescent properties significantly. According to the primary analysis, the green emission might be related to the oxygen vacancies in La2O2CO3 lattice.

Progress of Studies on Multi-Color Long Afterglow Luminescence Materials

Progress of studies on various multi-color long afterglow luminescence materials was reviewed.Two luminescent mechanism of long afterglow behavior were discussed.Further research and development prospects about the materials were proposed.

Effective model for rare-earth Kitaev materials and its classical Monte Carlo simulation

Recently,the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid(KSL)[Chin.Phys.Lett.38047502(2021)].In the present work,we firstly propose an effective spin Hamiltonian consistent with the symmetry group of the crystal structure.Then we apply classical Monte Carlo simulations to preliminarily study the model and establish a phase diagram.When approaching to the low temperature limit,several magnetic long range orders are observed,including the stripe,the zigzag,the antiferromagnetic(AFM),the ferromagnetic(FM),the incommensurate spiral(IS),the multi-Q,and the 120°ones.We further calculate the thermodynamic properties of the system,such as the temperature dependence of the magnetic susceptibility and the heat capacity.The ordering transition temperatures reflected in the two quantities agree with each other.For most interaction regions,the system is magnetically more susceptible in the ab-plane than in the c-direction.The stripe phase is special,where the susceptibility is fairly isotropic in the whole temperature region.These features provide useful information to understand the magnetic properties of related materials.

Study of Photostimulable Luminescence Materials Sr_9Ca(PO_4)_6Cl_2:Eu

The polycrystalline Sr_9Ca(PO_4)_6Cl_2:Eu has been synthesized by solid state reaction.The reaction condition,the appropriate raw materials and their quantity used,which may affect the photostimulable luminescence (PSL),have been systematically inves- tigated.The properties of this PSL phosphor as a material for storing and reproducing the X-ray image in computer-aided radiography have been reported briefly.

Sol Gel Assembly and Luminescence of SiO_2/PEMA Hybrid Material Incorporated with Terbium Complex

Ethyl methacrylate (EMA) doped with luminescent ternary terbium complex (Tb(acac) 3·dam) with acetylacetone (Hacac) and diantipylmethane (dam) was incorporated into the microporous silica gel. With the polymerization of EMA, the hybrid material containing Tb(acac) 3·dam was obtained. The hybrid material exhibited good toughness and transparency and higher thermal stability than that of the pure complex and pure polymer matrix. In the range of doping concentration of Tb(acac) 3·dam (0.05%, 0.1%, 0.2%, 0.5%, 1.0%, 2.0% and 5.0%), emission intensity increases with the increasing of corresponding doping concentration and concentration quenching effect has not taken place.

Surface modification of up-conversion luminescence material Na[Y_(0.57)Yb_(0.39)Er_(0.04)]F_4 with hydrosulfide group

A new method was reported for surface modification of an up-conversion luminescence material with hydrosulfide group. The factors that may influence the surface modification,such as reaction time,amount of catalyzer and modifier,and reaction solvent,were investigated. The optimal conditions were that the reaction time,the quantity of the basic catalyzer,the quantity of modifier and the volume of reaction solvent were 40 min,1.0,1.0,and 40 mL,respectively. The results indicated that hydrosulfide group content modified on the surface of up-conversion luminescence material reached to 0.1430 mmol/g,and this modified up-conversion luminescence material could be widely used in the study of structure of protein and the property of microenvironment.

Synthesis of Long Afterglow Phosphors MAl_2O_4∶Eu^(2+), Dy~ (3+)(M=Ca, Sr, Ba) by Microemulsion Method and Their Luminescent Properties

Long afterglow phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） were synthesized by microemulsion method, and their crystal structure and luminescent properties were compared and investigated. XRD patterns of samples indicate that phosphors CaAl2O4：Eu^2＋, Dy^3＋ and SrAl2O4 ： Eu^2＋, Dy^3＋ are with monoelinie crystal structure and phosphor BaAl2O4：Eu^2＋ , Dy^3＋ is with hexagonal crystal structure. The wide range of excitation spectrum of phosphors MAl2O4： Eu^2 ＋ , Dy^3＋ （M = Ca,Sr, Ba） indicates that the luminescent materials can he excited by light from ultraviolet ray to visible light and the maximum emission wavelength of phosphors MAl2O4：Eu^2＋ , Dy^3＋ （M = Ca, Sr, Ba） is found mainly at λem of 440 nm （M = Ca）, 520 nm （M = Sr） and 496 nm （M = Ba） respectively, the corresponding colors of emission light are blue, green and eyna-green respectively. The afterglow decay tendency of phosphors can he summarized as three processes： initial rapid decay, intermediate transitional decay and very long slow decay. Afterglow decay curves coincide with formula I = At^ - n, and the sequence of afterglow intensity and time is Sr 〉 Ca 〉 Ba.

Research progress in rare earths and their composites based electrode materials for supercapacitors

Supercapacitor is an imminent potential energy storage system,and acts as a booster to the batteries and fuel cells to provide necessary power density.In the last decade,carbon and carbonaceous materials,conducting polymers and transition metal oxide/hydroxide based electrode materials have been made to show a remarkable electrochemical performance.Rare-earth materials have attracted significant research attention as an electrode material for supercapacitor applications based on their physicochemical properties.In this review,rare earth metals,rare earth metal oxides/hydroxides,rare-earth metal chalcogenides,rare-earth metal/carbon composites and rare-earth metal/metal oxide composites based electrode materials are discussed for supercapacitors.We also discuss the energy chemistry of rare-earth metal-based materials.Besides the factors that affect the performance of the electrode materials,their evaluation methods and supercapacitor performances are discussed in details.Finally,the future outlook in rare-earth-based electrode materials is revealed towards its current developments for supercapacitor applications.

Preparation and Luminescence Properties of Gadolinium Aluminate Phosphor Material Chip

The combinatorial material chip approach is an excellent innovation for inorganic functional material research, and it can discover and screen new materials efficiently. In the present work, the approach was used to find quickly and improve gadolinium aluminate phosphors (Gd_ 1-xAl_yO_z∶RE_x). Under UV lamp excited (λ_ ex=254 nm) the Gd_ 1-xAl_yO_z∶RE_x phosphor material chip evaluation shows that the suitable n(Al)∶n(Gd) in host materials is 1∶1 for Eu and Tb ion activators. The luminescence character coherence between combinatorial material chip and parallelism powder samples produced by nitric-citric process was also confirmed.

Crystal structure and optical performance analysis of a new type of persistent luminescence material with multi-functional application prospects

Persistent luminescence (PersL) materials,as environmentally friendly and energy-saving materials,have broad application prospects in many fields such as lighting,chemistry and even biomedicine.However,studies on the types,performances and mechanism of PersL materials are still insufficient,which significantly restricts their development and application.Under this consideration,we successfully synthesized a yellow PersL material CaSrGa_(4)O_(8)(CSG).The crystal structure was studied in detail through Rotation Electron Diffraction (RED) and Powder X-ray Diffraction (PXRD).What’s more,by co-doping Mn^(2+) and Yb^(3+),the afterglow brightness of CSG could be increased by nearly 20 times,and the afterglow duration could reach more than 6 h.It is worth mentioning that the samples also have excellent performances in mechanical luminescence (ML),photostimulated luminescence (PSL) and cathodoluminescence (CL),which was also investigated systematically.Finally,an anti-counterfeiting label was designed by the samples to reveal the potential of their application in anti-counterfeiting.The results showed that our research not only provided a new candidate PersL material for multifunctional applications,but also gave good help for studying the physical and chemical properties of CSG.

Synthesis of Ultra-Fine SrAl_2O_4∶Eu, Dy Phosphor and Its Luminescent Properties

Precursor of SrAl_2O_4∶Eu, Dy phosphor was prepared by co-precipitation method, in which dispersing agent was added to control particle size. Microwave radiation method was used to synthesize SrAl_2O_4∶Eu, Dy phosphors. Experimental results show that the precursor was composed of crystalline ammonium dawsonite hydrate and strontium carbonate, and the adding of dispersing agent can effectively diminish precursor size. The precursor can be transformed to pure SrAl_2O_4 phase after being calcined for 40 min in microwave chamber. The phosphors possess good persistent luminescent properties, finer grain size ranged from 0.2 μm to 5 μm and better size distribution than that of solid-state reaction. The doping of B^(3+) will result in the increasing of crystallite size, but can effectively improve phosphors′ persistent luminescent properties.

Synthesis and Properties of Novel Luminescent Compounds Containing Triphenylamine and Bipyridine Units

Blue luminescent compounds T1―T4 containing triphenylamine donors,bipyridine acceptors and olefinic linkers were synthesized and characterized by 1 H NMR,13 C NMR and high resolution mass spectrometry（HRMS）.Four compounds T1―T4 exhibit excellent solubility in common solvents and good film forming properties.Quantum chemical calculations show that compounds T1―T4 have asymmetric linear structures and the proper highest occupied molecular orbital（HOMO） levels.The UV-Vis absorption and fluorescence emission spectra of the four compounds in dilute chloroform solutions and on the solid films were measured.It reveals that compounds T1―T4 exhibit similar spectral behavior,suggesting that these compounds can form amorphous state in solid films.The calculated absorption and emission spectra of compounds T1―T4 are in good agreement with experimentally determined ones.Compounds T1―T4 have absolute fluorescence quantum yield above 17% in dilute chloroform solutions.Four compounds possess high glass-transition temperature（T g） exceeding 97 ℃ and the maximum T g is 155.28 ℃ for compound T3.Cyclic voltammetry measurements show that these compounds have proper HOMO levels in a range of-5.01―-5.13 eV for hole injection.The properties of compounds T1―T4 indicate that these compounds are candidates for the application in organic light-emitting devices（OLEDs） as hole-transporting materials（HTMs）.