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.

Reversion of Bioluminescent Bacteria (Mutatox^(TM)) toTheir Luminescent State upon Exposure to OrganicCompounds, Munitions, and Metal Salts

Mutatox is a new genotoxicity bioassay which uses as the endpoint the bioluminescence produced on reversion of a dark strain of the marine bacterium Vibrio fischeri ±S9.Reversion can occur by several mechanisms, including base substitution, frame-shift, SOS induction, and DNA intercalation. For screening, Mutatox provides many advantages over the Salmonella trphimurium (Ames) assay: it requires minimal sterility, employs a shorter incubation period, and does not require culture maintenance. Eighteen organic chemicals (phenol, polynuclear aromatic hydrocarbons, nitrotoluenes, others), Na3PO4, and 4 genotoxic metals (Cu2+, Ni2+, As3+, Cd2+) were tested. Most of the organic compounds positive in S. typhimurium assays were positive in Mutatox. None of the metals was genotoxic in V. fischeri, possibly due to poor uptake from the saline medium

Luminescent characteristics of Ba_3Y_2(BO_3)_4:Eu^(3+) phosphor for white LED

The Ba3Y2（BO3）4：Eu^3＋ phosphor was synthesized using a high temperature solid-state reaction method and the luminescent characteristics were investigated. The emission spectrum exhibited one strong red emission at 613 nm, corresponding to the electric dipole 5D0-TF2 transition of Eu^3＋, under 365 nm excitation. The excitation spectrum of 613 nm indicated that the Ba3Y2（BO3）n：Eu^3＋ phosphor was effectively excited by ultraviolet （UV） （254, 365 and 400 nm） and blue （470 nm） light. The effect of Eu^3＋ concentration on the 613 nm emission of the Ba3Y2（BO3）n：Eu^3＋ phosphor was measured. The results showed that the emission intensity increased with increasing Eu^3＋ concentration, and then decreased. The CIE color coordinates of Ba3Y2（BO3）4：Eu^3＋ phosphor were x=0.641 and y=0.359 at 15 mol.% Eu^3＋.

Effect of Sintering Time on Luminescent Properties of YAG: Ce3+ Phosphors

Phosphors of yttrium aluminium garnet activated by cerium ion, a kind of yellow luminescent materials for white LED lighting, were synthesized via solid-state reaction route in air and then reducing atmospheres.Thermal analysis was conducted by DTA/TGA.Moreover, XRD patterns of phosphors show that pure cubic phase of Y3 Al5 O12 is formed.Microstructures of the powders were observed by SEM.Luminescent spectra of the phosphors were also characterized by a spectrophotometer.The effect of sintering time on excitation and emission properties of the YAG: Ce3+ powders were systematically studied, resulting a best range of sintering time, 300 ～ 400 min, for maximal relative luminescent intensity.

Synthesis, Crystal Structure and Luminescent Property of the One-dimensional Chain Chlorodibenzyltin 2-Quininate

A one-dimensional chain chlorodibenzyltin 2-quininate has been synthesized and characterized by IR, NMR spectra and elemental analysis. The crystal structure has been determined by X-ray diffraction. The crystal belongs to the monoclinic system, space group I4（—） with a = 19.1171（10）, b = 19.1171（10）, c = 12.5158（6） , Z = 8, V = 4574.1（4） 3, Dc = 1.477 g·cm-3, μ（MoKα） = 1.252 mm-1, F（000） = 2032, R = 0.0259 and wR = 0.0723. In the complex, the tin atom is six-coordinated to adopt a distorted octahedral configuration with bridging carboxyl of quinoline-2-carboxylic acid. The result of fluorescence spectrum analysis shows that the title complex at room temperature exhibits an intense photoluminescence with maximum emission at 364.2 nm （λex = 303.0 nm）.

Synthesis, Structure and Luminescent Property of a 2D Cd(Ⅱ) Coordination Polymer Based on Mixed-ligands of 1,3-Bis(imidazol)propane and Pyridine-3,5-dicarboxylic Acid

A new Cd（Ⅱ） coordination polymer, namely, [Cd（1,3-bip）（3,5-pdc）]n （1,3-bip = 1,3-bis（imidazol）propane and 3,5-pdc = pyridine-3,5-dicarboxylic acid） has been synthesized under hydrothermal conditions. Compound 1 was characterized by infrared spectrum, elemental analysis, powder X-ray diffraction （PXRD） and single-crystal X-ray diffraction analysis. It crystallizes in monoclinic, space group P21/c with a = 1.40178（7）, b = 1.72502（12）, c = 1.41635（6） ran, β = 92.653（4）°, V = 3.4212（3） nm3, Z = 4, C16HIsCdNsO4, Mr = 453.73, Dc = 1.762 g/cm3, F（000） = 1808,μ = 1.310 mm1, R = 0.0899 and wR = 0.1945. In compound 1, each 3,5-pdc ligand links three Cd（lI） ions and each Cd（Ⅱ） attaches to bip ligands to form a complicated 2D double-layer structure. In addition, the thermal stability and luminescent property of 1 have been studied in the solid state at room temperature.

Synthesis, Structure, and Luminescent and Dielectric Properties of a Novel 1D Chain Zinc(Ⅱ) Complex {[Zn(DCImPyO)·(H_2O)_2·]·H_3O}_n

Under hydrothermal conditions, 4-（4,5-dicarboxy-lH-imidazol-2-yl）pyridine 1-oxide （H3DCImPyO） reacted with ZnC12 to give the 1D chain complex {[Zn（DCImPyO）·（H2O）2·]·H3O}n （1）. Single-crystal X-ray determination shows that complex 1 crystallizes in the monoclinic system, space group P21/c with a = 9.488（2）, b = 13.247（3）, c = 12.959（4） A, β = 126.716（19）°, Z = 4, V= 1305.6（6）/k3, C10H11N3O8Zn, Dc = 1.865 g/cm3, Mr = 366.61, 2（MoKa） = 0.71073 A, μ= 1.930 mm1, F（000） = 744, R = 0.0472 and wR = 0.1487. Fluorescent analysis showed an intense emission band at 422 nm when the exciting radiation was set at 378 nm. Dielectric constant of complex 1 was measured at different frequencies with temperature variation.

Synthesis, Crystal Structure and Luminescent Property of a Ag(Ⅰ) Coordination Polymer with a 3D Sandwich-like Framework

A new coordination polymer,{[Ag2（bpp）2（H2O）2]·bpdc·3H2O}n,derived from the ligand biphenyl-4,4＇-dicarboxylic acid（H2bpdc）,has been obtained through a hydrothermal technique（bpp = l,3-bis（4-pyridyl）propane）.Its single-crystal structure has been characterized by single-crystal X-ray diffraction,powder XRD,FT-IR,TGA and elemental analysis techniques.The single-crystal X-ray diffraction reveals that complex 1 consists of 1D infinite[Ag（bpp）（H2O）]n^（n＋）cationic chains,2D anionic layer constructed by bpdc anions and free water which provide charge compensation in the crystal structure.The 1D infinite[Ag（bpp）（H2O）]n^（n＋） cationic chains and 2D anionic layer are further stacked in-ABAB- fashion through intermolecular H-bonding to form a 3D sandwich-like framework.In addition,the luminescent property of complex 1 in the solid state at room temperature was investigated.

Luminescent properties of Ca_2SiO_4:Eu^(3+) red phosphor for trichromatic white light emitting diodes

The luminescent properties of Eu^3＋doped Ca2SiO4 red phosphors synthesized by the flux fusion reaction method were investigated. It was found that the excitation spectrum included two regions： the weak excitation band below 325 nm and strong narrow peaks above 325 nm. The main peak of the excitation band was located at 400 nm. The peaks located at 290 nm were assigned to the combination of the charge transfer transition of O-Eu, peaks above 325 nm （325, 385, 400, 470, 511, and 539 nm） were assigned to the f-f transitions of Eu^3＋. The emission spectrum was dominated by the red peak located at 612 nm due to the electric dipole transition of ^5D0-^7F2. In addition, the effects of the Eu^3＋ content and charge compensators of Li^＋, Na^＋, K^＋, and Cl^- ions on the emission intensity were investigated. The experiment results suggested that the strongest emission was obtained when the concentration of the Eu^3＋ ions was 0.3 mol^-1, and Li^＋ ions gave the best improvement to enhance the emission intensity. Ca2SiO4：Eu^3＋, Li^＋ was thus suitable for low-cost trichromatic white light emitting diodes （WLED） based on UV InGaN chip.

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.

EffectofEr^(3+) and Nd^(3+)doping on the luminescent properties of BaMgAl_(10)O_(17):Euphosphor

BaMgAl_(10)O_(17):Eu blue phosphors were synthesized and the effect of dopingE^(3+) and Nd^(3+) ions in the phosphor on the luminescent properties was investigated. When thecontent of Er^(3+) and Nd^(3+) ions is small, the phosphor remains single phase and the luminescentintensity of Eu^(2+) increases effectively. When Er^(3+) is doped, the shape of the excitationspectrum of the phosphor in the UV (ultraviolet) region remains unchanged. As Nd^(3+) is doped inthe phosphor, the location and intensity of the two excitation peaks, and the emission intensityratio excited by corresponding UV change dramatically owing to the alternation of crystal fieldsplitting and level barycenter of 4f^6 5d configuration of Eu^(2+) ion.

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.

A New One-dimensional Coordination Polymer Based on 3,5-Dinitro-salicylic Acid:Synthesis,Crystal Structure,Luminescent Property and Theoretical Calculation

A new one-dimensional Mg（Ⅱ） coordination polymer, [Mg（L）（phen）（H2O）]（1）, has been hydrothermally synthesized by using 3,5-dinitro-salicylic acid（H2L） and 1,10-phenanthroline（phen）. It crystallizes in monoclinic, space group C2/c with a = 33.038（7）, b = 6.6481（13）, c = 22.750（5） A, β = 126.99（3）°, V = 3991.1（14） A3, Z = 8, C19H12 MgN4O8, Mr = 448.64, Dc = 1.493 g/cm3, F（000） = 1840, μ（Mo Ka） = 0.146 mm-1, R = 0.0559 and w R = 0.0975. In 1, each L anion bridges two Mg（Ⅱ） atoms to give one-dimensional zigzag chains with the Mg…Mg separation of 5.34 ？, which are extended by π-π stacking interactions between 1,10-phenanthroline ligands into a two-dimensional supramolecular layer. Moreover, the O–H…O hydrogen-bonding interactions further stabilize the layer structure of 1. The luminescent property was also studied for 1 in solid state at room temperature. In addition, natural bond orbital（NBO） analysis was performed by the B3LYP/LANL2 DZ method in Gaussian 09 Program. The calculation results show obvious covalent interaction between the coordinated atoms and Mg（Ⅱ） ion.

Origin of Luminescent Centers and Edge States in Low-Dimensional Lead Halide Perovskites:Controversies,Challenges and Instructive Approaches

With only a few deep-level defect states having a high formation energy and dominance of shallow carrier non-trapping defects,the defect-tolerant electronic and optical properties of lead halide perovskites have made them appealing materials for high-efficiency,low-cost,solar cells and light-emitting devices.As such,recent observations of apparently deep-level and highly luminescent states in low-dimensional perovskites have attracted enormous attention as well as intensive debates.The observed green emission in 2D CsPb2Br5 and 0 D Cs4PbBr6 poses an enigma over whether it is originated from intrinsic point defects or simply from highly luminescent CsPbBr3 nanocrystals embedded in the otherwise transparent wide band gap semiconductors.The nature of deep-level edge emission in 2D Ruddlesden–Popper perovskites is also not well understood.In this mini review,the experimental evidences that support the opposing interpretations are analyzed,and challenges and root causes forthe controversy are discussed.Shortcomings in the current density functional theory approaches to modeling of properties and intrinsic point defects in lead halide perovskites are also noted.Selected experimental approaches are suggested to better correlate property with structure of a material and help resolve the controversies.Understanding and identification of the origin of luminescent centers will help design and engineer perovskites for wide device applications.

A New 1D Cadmium Coordination Polymer Based on N- and O-donor Ligands: Synthesis, Structure and Luminescent property

One new cadmium coordination polymer, [Cd（nbdc）（dmpy）]n （1, H2nbdc = 2-nitro- terephthalic acid, dmpy = 5,5′-dimethyl-2,2′-bipyridine） has been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis （TGA）, and single-crystal X-ray diffraction. Complex 1 is of monoclinic system, space group C2/c with a = 11.7684（9）, b = 24.3715（19）, c = 13.9898（11） , β = 107.652（2）°, V = 3823.5（5） 3, C20H15N3O6Cd, Z = 8, Mr = 505.75, Dc = 1.757 g/cm3, μ（MoKα） = 1.187 mm-1, F（000） = 2016, the final R = 0.0207 and wR = 0.0560 for 3034 observed reflections with I 〉 2σ（I）. 1 exhibits an interesting one-dimensional double chain structure. Furthermore, the luminescent property of 1 has also been investigated.

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.

Controlled Assembly of Luminescent Lanthanide‑Organic Frameworks via Post‑Treatment of 3D‑Printed Objects

Complex multiscale assemblies of metal-organic frameworks are essential in the construction of largescale optical platforms but often restricted by their bulk nature and conventional techniques.The integration of nanomaterials and 3D printing technologies allows the fabrication of multiscale functional architectures.Our study reports a unique method of controlled 3D assembly purely relying on the post-printing treatment of printed constructs.By immersing a 3D-printed patterned construct consisting of organic ligand in a solution of lanthanide ions,in situ growth of lanthanide metal-organic frameworks(LnMOFs)can rapidly occur,resulting in macroscopic assemblies and tunable fluorescence properties.This phenomenon,caused by coordination and chelation of lanthanide ions,also renders a sub-millimeter resolution and high shape fidelity.As a proof of concept,a type of 3D assembled LnMOFsbased optical sensing platform has demonstrated the feasibility in response to small molecules such as acetone.It is anticipated that the facile printing and design approach developed in this work can be applied to fabricate bespoke multiscale architectures of functional materials with controlled assembly,bringing a realistic and economic prospect.

Synthesis and Luminescent Properties of Ce^(3+), Tb^(3+) Co-Doped Zn_4B_6O_(13)

Green-photoluminescence material Zn4B6O13: Ce3+, Tb3+ was first synthesized by spread method of high temperature and solid state reaction, which is cubic crystal system with lattice parameters: a(0) = 0.7472 nm, V = 0.4172 nm(3), and structural properties are investigated by XRD. The excitation and emission band of Ce3+ ion single-doped in Zn4B6O13 transfer longer spectra 2.38 similar to 4.94 kk than in other matrices. Emission band of Ce3+ ion better overlaps with the F-7(6)-->(5)G(2),D-5(1),H-5(7) absorption band of Tb3+. It shows that emission of Tb3+ ion is sensitized by Ce3+. In Zn4B6O13:Ce3+, Tb3+, it is due to the energy transfer mechanism, resonance transfer of electric multipolar interaction of the dipole-dipole between Ce3+-->Ce3+ and Ce3+-->Tb3+. The color coordinates of Zn4B6O13: X 0.281, gamma = 0.619. The mean diameter of the particles is 0.23 mum.

Synthesis, Crystal Structure and Luminescent Property of [Zn(C_(12)H_9O_3)_2(C_(10)H_8N_2)]_n·nH_2O

Under hydrothermal condition, the reaction of 2-naphthoxyacetic acid with ZnCl2 and 4,4′-bipyridine （4,4′-bipy） has afforded a new Zn（Ⅱ） compound, [Zn（C12H9O3）2（C10H8N2）]n·nH2O1, which was structurally characterized by single-crystal X-ray diffraction analysis. The crystal is of monoclinic, space group P21/c with a = 7.7335（2）, b = 19.3834（4）, c = 20.1707（4） A, β = 104.9830（10）°, V = 2920.82（11） A^3, C34H28ZnN2O7, Mr = 641.95, Z = 4, Dc = 1.460 g/cm^3,μ = 0.895 mm^-1, F（000） = 1328, R = 0.0406 and wR = 0.0876 for 4417 observed reflections （I〉 2σ（I）） Complex 1 consists of one-dimensional zigzag chains deriving from Zn（C12H9O3）2 units linked by 4,4′-bipy ligands, and lattice water molecules decorate between the chains. Non-covalent interactions, such as hydrogen-bonding and aromatic π-π interactions, lead to the formation of a 3D network structure. The thermogravimetric analysis （TGA） and luminescent property for 1 have also been studied in this paper.

A New 1D Zinc Coordination Polymer Constructed by 1-Naphthylacetate and 4,4'-bpy:Synthesis,Structure and Luminescent Property

One new zinc coordination polymer,[Zn（NAA）2（4,4＇-bpy）]n（1,HNAA = 1-naphthaleneacetic acid,4,4＇-bpy = 4,4＇-bipyridine）,has been synthesized under hydrothermal conditions and characterized by elemental analysis,IR spectroscopy,thermogravimetric analysis（TGA）,and single-crystal X-ray diffraction.Coordination polymer 1 is of monoclinic system,space group Cc with a = 9.8720（6）,b = 16.7397（9）,c = 17.0371（12） ,β = 104.8080（10）°,V = 2721.9（3）3,C34H26N2O4Zn,Z = 4,Mr = 591.94,Dc = 1.444 g/cm3,μ（MoKα） = 0.946 mm-1,F（000） = 1224,the final R = 0.0282 and wR = 0.0720 for 3300 observed reflections with I 〉 2σ（I）.1 exhibits an interesting one-dimensional chain structure.Furthermore,the luminescent property of 1 has also been investigated.