稀土离子4f~(N-1)n'1'高激发态能级的研究

本论文系统地研究了稀土离子的4fN-1n'l'高激发组态能级问题。利用稀土光谱理论，推导了自由离子状态下的高激发组态4fN-1n'l'的能级表达式（包括电子的库仑和旋轨作用），编写了计算机程序，首次得到了660项4fN-1n'l'（n'l'=5d，6s，6p）组态主要较低能级的详细表达式，大大扩展了以往的计算结果。同时，具备了计算4fN-1n'l'组态的全部能级表达式的能力。利用复杂晶体的化学键介电理论，研究了基质中fN-15d组态能级移动和劈裂等问题，获得了如下创新性的成果：研究了晶体中稀土离子的4fN-15d组态的禁戒跃迁能级与允许跃迁能级之间的能级差变化现象。发现fd电子间库仑作用的交换积分项是能级差的主要作用并找到了在不同基质中影响能级差发生变化的因子：he＝[Σfc（i）a（i）Q（i）2]1/2，可用来分析、确定和预测Dy3+，Tb3+在不同基质中的禁戒跃迁峰的能级位置，对其它稀土离子也具有一定的指导意义。通过对自由离子能级差问题的分析，发现对不同稀土离子，能级差随f电子的增加而减小的规律，这样，无论是从横向还是纵向都可以对稀土离子的能级差进行比较，相互确定。为分析光谱中的禁戒跃迁峰提供了理论依据。研究了晶体中Ce3+、Eu2+的4fN-15d组态能级中心下移现象，发现影响其发生变化的因素与能级差的相同，但两者具有不同的变化形式，前者与玩呈一级指数关系，后者与he呈线性关系。从指数关系式中推导得到的自由离子状态下能级中心位置与实验值吻合较好。当he趋向于极大值时，得到的Ce3+、Ey2+的4fN-15d组态能级中心极限值相应于离子所含电子动能的大小。研究了晶体中Ce3+、Eu2+的4fN-15d组态能级劈裂问题，结合实验结果，发现立方场下的能级劈裂与化学键的同极化作用能，中心离子的配位数，配体离子的有效电荷以及所成键的离子性相关，并具此得到一个劈裂因子参数：Fc＝EhQfi/NFc与10Dq值呈现很好的线性关系。研究结果表明，无论是4fN-15d组态的能级劈裂还是能级中心下降问题，Ce3+、Eu2+两离子都可以表达成统一的形式，显示了环境因子he与劈裂因子Fc所具有的普适性，对其它稀土离子的4fN-1n'l，高激发组态能级同样也具有理论指导意义。

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in-situ formed lanthanide complexes

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film.

The optical properties and the natural lifetime calculation of a Sm(III) complex

The photophysical properties of the complex Sm(PM)(3)(TP)(2) [PM = 1-phenyl-3-methyl-4-isobutyryl-5-pyrazolone, TP = triphenyl phosphine oxide] are determined in crystal state, and energy transfer process is modeled for ligands to center Sm(III) ion. The characteristic luminescence of Sm(III) is sensitized by PM and TP, and most of transitions from excited state (4)G(5/2) of Sm3+ are detected.

Near-infrared luminescence from sol-gel materials doped with holmium(III) and thulium(III) complexes

A series of ternary Ln(tta)(3)L complexes (Ln = Ho, Tm; Htta = 2-thenoyltrifluoroacetone; L = 1,10-phenanthroline, 2,2'-bipyridine, or triphenyl phosphate oxide) and their corresponding sol-gel hybrid materials formed via the in situ synthesis process (designated as Ln-T-L gel) were reported. The complexes and the gels were studied in detail, which suggest the complexes have been successfully synthesized in the corresponding gels.

1.54 mu m near-infrared photoluminescent and electroluminescent properties of a new Erbium (111) organic complex

The crystal structure of Er(PM)(3)(TP)(2) [PM = 1-Phenyl-3-methyl-4-isobutyryl-5-pyrazoloiie, TP = triphenyl phosphine oxide] was reported and its photoluminescence properties were studied by UV-vis absorption, excited, and emission spectra. The Judd-ofelt theory was introduced to calculate the radiative transition rate and the radiative decay time of 3.65 ms for the I-4(13/2) -> I-4(15/2) transition of Er3+ ion in this complex.

Energy transfer and tunable luminescence properties of Eu3+ in TbBO3 microspheres via a facile hydrothermal process

Tb(1-x)BO3:xEu(3+) (x = 0-1) microsphere phosphors have been successfully prepared by a simple hydrothermal process directly without further sintering treatment. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), photoluminescence (PL), low-voltage cathodoluminescence (CL), and time-resolved emission spectra as well as lifetimes were used to characterize the samples.

Energy transfer from Tb3+ to Mn2+ in LaMgAl11O19:Tb, Mn phosphors

Luminescent properties of LaMgAl11O19:Tb, Mn phosphors were investigated. It was observed that the energy distributions of the Tb3+-emission bands associated with transitions from the D-5(3) and D-5(4) levels to F-7(J) depend on the Tb3+-concentration, which is due to the cross-relaxation between Tb 31 ions. The emission band at about 516 nm is attributed to the T-4(1) -> (6)A(1) transition of the Mn2+ ions. We observed an energy transfer from the Tb 3, to Mn2+ ions in LaMgAl11O19:Tb, Mn.

Synthesis and fluorescent property of NH4Y1.9Eu0.1F7 nanoparticles with the temperature effect on the morphology

Sphere NH4Y1.9Eu0.1F7 nanoparticles were successfully synthesized by a hydrothermal method at 180 degrees C for 10 h. SEM and TEM images show the particles are spheres and have lots of hollows in them. The mean particle size is about 60 nm. The shape and size of the particles can be controlled by changing temperature and time of reactants. The luminescent property of the sample indicates that strong emission peaks of the Eu3+ ions are located at about 589 and 612 mm.

Selective synthesis of hexagonal and monoclinic LaPO4:Eu3+ nanorods by a hydrothermal method

The hexagonal and monoclinic LaPO4:Eu3+ nanorods can be selectively synthesized through a simple hydrothermal method by only adjusting the reaction temperature. Hexagonal and monoclinic LaPO4:Eu3+ nanorods can be prepared at 120 and 180 degrees C, respectively. The phase conversion of LaPO4:Eu3+ under different temperatures is investigated in detail. Moreover, the influence of the temperature on the intensity and the shift of the peaks of the excitation and emission spectra is discussed, and the decay lifetime of the Eu3+ ions of the sample obtained at different temperature also have been investigated in this paper.

Near-infrared luminescent properties and natural lifetime calculation of a novel Er3+ complex

in this communication, a novel Er3+ complex Er(PT)(3)TPPO [PT = 1-phenyl-3-methyl-4-tert-butylbenzoyl-5-pyrazolone, TPPO = triphenyl phosphine oxide] is successfully synthesized and characterized by elemental analysis and single-crystal X-ray diffraction. Its optical properties and the energy transfer process from the ligand PT to the Er3+ ion are investigated, the typical near-infrared (NIR) luminescence (centered at around 1530 nm) is attributed to the I-4(13/2) -> I-4(15/2) transition of Er3+ ion which results from the efficient energy transfer from PT to Er3+ ion (an antenna effect). The wider full width at half maximum (78 nm) peaked at 1530 nm in the emission spectrum and the Judd-Ofelt theory calculation on the radiative properties suggest that Er(PT)(3)TPPO should be a promising candidate for tunable lasers and planar optical amplifiers.

The near-infrared optical properties of an Nd (III) complex and its potential application in electroluminescence

A trivalent neodymium ion (Nd3+) complex Nd(PM)(3)(TP)(2) was synthesized, and its optical properties was studied by introducing Judd-Ofelt theory to calculate the radiative transition rate and the radiative decay time of the F-4(3/2) -> (4)l(J), transitions in this Nd(III) complex. The strong emissions of this complex at near-infrared region were owing to the efficient energy transfer from ligands to center metal ion. The potential application of this complex in NIR electroluminescence was studied by fabricating several devices. The maximum NIR irradiance was obtained as 2.1 mW/m(2) at 16.5 V.

Novel Near-Infrared Luminescent Hybrid Materials Covalently Linking with Lanthanide [Nd(III), Er(III), Yb(III), and Sm(III)] Complexes via a Primary beta-Diketone Ligand: Synthesis and Photophysical Studies

A series of novel, colorless, and transparent sot-gel derived hybrid materials Ln-DBM-Si covalently grafted with Ln(DBM-OH)(3)center dot 2H(2)O (where DBM-OH = o-hydroxydibenzoylmethane, Ln = Nd, Er, Yb, and Sin) were prepared through the primary beta-diketone ligand DBM-OH. The structures and optical properties of Ln-DBM-Si were studied in detail. The investigation results revealed that the lanthanide complexes were successfully in situ grafted into the corresponding hybrids Ln-DBM-Si. Upon excitation at the maximum absorption of ligands, the resultant materials displayed excellent near-infrared luminescence.

Relationship between charge transfer energies of Yb3+ and Sm3+ and crystal environmental factor

Relationship between charge transfer energies E-CT of Yb3+ and Sm3+ and environmental factors h(e) in various crystals was investigated using a dielectric chemical bond method. Both results show that they have an exponential relation E-CT = A+B exp(-kh(e)), but the exponential factors are different, which indicates that the interaction between the rare earth ions and environment is connected with the kind of rare earth ion. This result provides a method of determining charge transfer energies of Yb3+ and Sm3+ from a crystal structure.

One-Dimensional Ce3+- and/or Tb3+-Doped X-1-Y2SiO5 Nanofibers and Microbelts: Electrospinning Preparation and Luminescent Properties

One-dimensional X-1-Y2SiO5:Ce3+ and -Tb3+ nanofibers and quasi-one-dimensional X-1-Y2SiO5:Ce3+ and -Tb3+ microbelts have been prepared by a simple and cost-effective electrospinning process. X-ray powder diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry, transmission electron microscopy, high-resolution transmission electron microscopy, photoluminescence (PL), and cathodoluminescence spectra were used to characterize the samples. SEM results indicate that the as-prepared fibers and belts are smooth and uniform with a length of several tens to hundreds of micrometers, whose diameters decrease after being annealed at 1000 degrees C for 3 h. Under ultraviolet excitation and low-voltage electron beam excitation, the doped rare earth ions show their characteristic emission, that is, Ce3+ 5d-4f and Tb3+ D-5(4)-F-7(J) (J = 6, 5 4, 3) transitions, respectively.

Spindle-like Lanthanide Orthovanadate Nanoparticles: Facile Synthesis by Ultrasonic Irradiation, Characterization, and Luminescent Properties

A general and facile ultrasonic irradiation method has been established for the synthesis of the lanthanide orthovanadate LnVO(4) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) nanoparticles from an aqueous solution of Ln(NO3)(3) and NH4VO3 without any surfactant or template. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra as well as kinetic decays were employed to characterize the as-prepared products. Ultrasonic irradiation has a strong effect on the morphology of the LnVO(4) nanoparticles. The SEM and TEEM images illustrate that the as-formed LnVO(4) particles have a spindle-like shape with an equatorial diameter of 30-70 nm and a length of 100-200 am, which are the aggregates of even.