Luminescence Properties of Tb^(3+)-Doped LuAG Films Prepared by Pechini Sol-Gel Method

Lu3Al5O12（LuAG） thin films with different Tb^3＋ concentration were prepared on carefully cleaned （111 ） silicon wafer by a Peehini process and dip-coating technique. Heat treatment was performed in the temperature range from 800 to 1100 ℃. The crystal structure was analyzed by XRD. The results show that LuAG film starts to crystallize at about 900 ℃, and the particle size increases with the sintering temperature. Excitation and emission spectra of Tb^3＋ doped LuAG films were measured. The effects of heat-treatment temperature and doping concentration of Th3 ＋ on the luminescent properties were also investigated. For a comparison study, Th^3＋-doped LuAG powders were also prepared by the same sol-gel method.

Luminescence Properties of Sm^(3+) doped Bi_2ZnB_2O_7

The phosphors of （Bi1- x Smx ） 2ZnB2O7 （ x = 0. 01, 0. 03, 0. 05, 0. 07, and 0. 09） were synthesized by conventional solid state reaction. The purity of all samples was checked by X-ray powder diffraction （XRD）. XRD analysis shows that all these compounds are of a single phase of Bi2ZnB2O7, indicating that the Bi^3＋ in Bi2ZnB2O7 can be partly replaced by the Sm^3＋ without the change of crystal structure. The excitation and emission spectra at room temperature show the typical 4f-4f transitions of Sm^3＋ . The dominant excitation line is around 404 nm due to ^6H5/2→^4K11/2 and the emission spectrum consists of a series of lines at 563, 599, 646, and 704 nm due to ^4G5/2→^6H5/2, ^6H7/2, ^6H9/2, and ^6H11/2, respectively. The optimal concentration of Sm^3＋ in Bi2ZnB2O7 is about 3mol% （relative to lmol Bi^3＋ ） and the critical distance Rc was calculated as 2.1 nm. The temperature dependence of the emission intensity of Bi1.94Sm0.06ZnB2O7 was examined in the temperature range between 100 and 450 K. The quenching temperature where the intensity has dropped to half of the initial intensity is 280 K. The lifetime for Sm^3＋ in Bi1.94Sm0.06ZnB2O7 is fitted as a value of 0.29 and 1.03 ms.

Luminescence Properties and Crystal Growth of Er/Yb Codoped KGd(WO_4)_2

In this paper, the spectral and luminescence properties of a series of KGd（WO4）2 powder samples codoped with different concentrations of Er^3＋ and Yb^3＋ were reported,and the best doping concentrations were found to be lat% Er^3＋ and 10at% Yb^3＋ for attaining the strongest intensity. The Er^3＋/yb^3＋ codoped KGd（WO4）2 crystal with good optical quality was grown by the TSSG method and the growth conditions were presented. The unpolarized absorption and emission spectra of the crystal have been measured. The strong absorption peak is at 980 nm with a FWHM of 65 nm, and the emission peak is at 1536 nm when pumped by 976 rim. The fluorescence lifetime of manifold ^4I13/2 is estimated to be 4.5 ms at room temperature.Investigations of Er, Yb：KGW crystal have shown it to have necessary combination of properties to get an effective generation of - 1.54 μm eye-safe radiation with laser diode pumping.

Synthesis and Luminescence Properties of Green-emitting Phosphor CaSc_(2)O_(4):Ce^(3+)

Using CaCO_(3),Sc_(2)O_(3),and CeO_(2) as raw materials,we prepared the CaSc_(2)O_(4):Ce^(3+)green phosphors for white light LEDs via a high-temperature solid-phase method in a reducing atmosphere.X-ray diffraction(XRD),field emission scanning electron microscopy(FESEM),fluorescence spectroscopy and other means were used to characterize the phase structure,apparent morphology,and photoluminescence properties of the product.CaSc_(2)O_(4) was synthesized under a reducing atmosphere(95%N_(2)+5%H_(2))at 1400℃ for 4 hours.Upon excitation with a blue light(450 nm wavelength),CaSc_(2)O_(4):Ce^(3+)displays a broadband green emission peak at 525 nm.The color coordinates of CaSc_(2)O_(4):7%Ce^(3+)emission peak are(0.3712,0.5940),and the product morphology is 1μm granular.Hence,it acts as a green phosphor suitable for white LEDs that can be excited by blue light.

The Luminescence Properties and Intramolecular Energy Transfer of Rare Earth Complexes with Aromatic Carboxylic Acids

The triplet state energies of para aminobenzoic acid and nicotinic acid were determined by means of low temperature phosphorescence spectrometry.The energy matches between them and the resonant emitting energy levels of Eu^(3+),Tb^(3+),Sm^(3+),Dy^(3+)were studied.The intramolecular energy transfer processes from the two aromatic carboxylic acid ligands to rare earth ions were also discussed on the basis of the measurement results of luminescence intensities,lifetimes and quantum efficiencies.

Hydrothermal Synthesis, Crystal Structure and Luminescence Properties of a New 2D Cadmium Complex Based on the 4,4'-Bis(benzimidazol-1-ylmethy1)biphenyl and Glutaric Acid Ligands

A new polymeric complex {[Cd2（bbmb）2（gt）2]＇（H2O）2}, （bbmb = 4,4＇-bis（benzimidazol-l-ylmethyl）biphenyl, H2gt = glutaric acid） has been obtained by hyclrothermal method and structurally characterized by elemental analysis, IR, XRD, TGA and single-crystal X-ray diffraction. The complex belongs to the triclinic system, space group P1 with a = 10.2417（15）, b = 13.752（2）, c = 22.201（3） A, a = 73.899（2）, β = 88.416（2）, y = 78.305（2）°, V = 2940.4（7） A3, Z = 2, C66H56Cd2N808, Mr = 1313.99, Dc = 1.484 g/cm3, F（000） = 1336 and μ = 0.787 mm-1, and features a 2D network. In the solid state at room temperature, the cadmium（Ⅱ） complex exhibits strong fluorescence absorption at 435 nm （λmax）.

Structural, Optical and Luminescence Properties of ZnO Thin Films Prepared by Sol-Gel Spin-Coating Method： Effect of Precursor Concentration

Transparent zinc oxide（ZnO） thin films are fabricated by a simple sol-gel spin-coating technique on glass substrates with different solution concentrations（0.3-1.2 M） using zinc acetate dehydrate [Zn（CH_3COO）_2·2H_2O] as precursor and isopropanol and monoethanolamine（MEA） as solvent and stabilizer, respectively. The molar ratio of zinc acetate dehydrate to MEA is 1.0. X-ray diffraction, ultraviolet-visible spectroscopy and photoluminescence spectroscopy are employed to investigate the effect of solution concentration on the structural and optical properties of the ZnO thin films. The obtained results of all thin films are discussed in detail and are compared with other experimental data.

Structures and luminescence properties of Yb^(3+) in the double perovskites Ba_2 YB'O_6 (B'=Ta^(5+),Nb^(5+) phosphors

The Yb3＋ doped Ba2YB＇O6 （B＇= Ta5＋, Nb5＋） were prepared by high temperature solid-state reaction method, their structures were determined by x-ray diffraction and refined by Rietveld method. The diffuse reflection absorption, excitation and emission spectra of yb3＋：Ba2YB＇O6 （B＇= Ta5＋, Nb5＋） were measured at room temperature. Under the excitation of ultraviolet light, these phosphors exhibit broad charge transfer band emissions of TaO6 or NbO6 centre with large Stokes shift. The Yb3＋ doped into these hosts are situated at y3＋ sites of cubic symmetry （Oh）. The experimental energy levels of Yb3＋ in Ba2YTaO6 and Ba2YNbO6 were determined by photoluminescence and diffuse reflection absorption spectra. Their wavefunctions and theoretical energy levels were obtained by diagonalising the Hamiltonian matrix. The experimental energy levels were fitted by Levenberg-Marquardt iteration algorithm to determine crystal field parameters. Then, the magnetic-pole transition line strengths of yb3＋：Ba2YB＇O6 （B＇=Ta5＋, Nb5＋） from （2F5/2）Г8-to the low-energy states were calculated.

Stability and luminescence properties of CsPbBr_(3)/CdSe/Al core-shell quantum dots

To improve the stability and luminescence properties of CsPbBr_(3)QDs,we proposed a new core-shell structure for CsPbBr_(3)/CdSe/Al quantum dots(QDs).By using a simple method of ion layer adsorption and a reaction method,CdSe and A1 were respectively packaged on the surface of CsPbBr_(3)QDs to form the core-shell CsPbBr_(3)/CdSe/Al QDs.After one week in a natural environment,the photoluminescence quantum yields of CsPbBr_(3)/CdSe/Al QDs were greater than 80%,and the PL intensity remained at 71%of the original intensity.Furthermore,the CsPbBr_(3)/CdSe/Al QDs were used as green emitters for white light-emitting diodes(LEDs),with the LEDs spectrum covering 129%of the national television system committee(NTSC)standard color gamut.The core-shell structure of QDs can effectively improve the stability of CsPbBr_(3)QDs,which has promising prospects in optoelectronic devices.

SPECTRAL VARIATION AND CHARACTERISTICS OF LOW VALENCY RARE EARTH IONS IN COMPLEX OXIDESⅢ.EFFECT OF THE CRYSTAL ENVIRONMENT AND CHEMICAL FACTORS ON LUMINESCENCE PROPERTIES OF EUROPIUM (Ⅱ) ION

In this paper,the influence of crystal-field on the Luminescence properties of Eu^(2+) in complex oxides are studied theoretically by using purely electrostatic model,the dependence of the 4f^65d levels on Eu-O bond distance is given.Quantum chemistry calculation shows that the splitting extent of 4f^65d energy band in cubic or in octahedral fields will be inversely proportional to R^5,where R is the distance of Eu^(2+) to oxygen ligand.The value of R affects slightly the location of the centre of 4f^65d energy band.According to the exper- imental spectrum data,we have discussed the influence of the host chemical composition,the replaced sites of Eu^(2+) and degree of covalency of Eu-O bond on luminescence properties of Eu^(2+).Some regularity of fluorescence spectrum was observed. In alkali-alkaline earth-phosphates,the splitting extent of 4f^65d band (△E) becomes smaller as the Eu-O bond distance (R) increases.In Na_(3-x)(PO_4)_(1-x)(SO_4)_x and Na_(2-x)CaSi_(1-x)P_xO_4 hosts,d-d emission peak of Eu^(2+) will shift to shorter wavelength with the increase of x's value. The crystal structure data show that Eu^(2+) in K_2Mg_2(SO_4)_3 is affected more strongly by crystal-field and covalancy than in KMgF_3,so K_2Mg_2(SO_4)_3:Eu^(2+) emits blue light (E_(em)~m=400nm) and KMgF_3:Eu^(2+) produces ultraviolet fluorescence.

Crystallization and Luminescence Properties of Sm3＋-Doped SrO-Al2O3-SiO2 Glass-Ceramics

The Sm^（3＋）-doped SrO-Al2O3-SiO2（SAS） glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-ceramics were investigated by DTA, XRD, SEM and luminescence spectroscopy. The results indicate that the crystal phase precipitated in this system is monocelsian（SrAl2Si2O） and with the increase of nucleation/crystallization temperature, the crystallite increases from 66 % to 79 %. The Sm（3＋）-doped SAS glass-ceramics emit green, orange and red lights centered at 565, 605, 650 and 715 nm under the excitation of 475 nm blue light which can be assigned to the 4 G5/2→6 Hj/2（j=5, 7, 9, 11） transitions ofSm^（3＋）, respectively. Besides, by increasing the crystallization temperature or the concentration ofSm^（3＋）, the emission lights of the samples located at 565, 605 and 650 nm are intensified significantly. The present results demonstrate that theSm^（3＋）-doped SAS glassceramics are promising luminescence materials for white LED devices by fine controlling and combining of these three green, orange and red lights in appropriate proportion.

Synthesis and luminescence properties of rare earth ternary complexes consisting of Tb(Ⅲ), β-diketones and 1,10-phenanthroline (phen)

In order to study the luminescent properties of ternary rare earth complexes with fl-diketone ligand, three new β-diketone ligands, 1-phenyl-3-（p-phenylethynylphenyl）-1,3-propanedione（HPPP）, 1-（2-thienyl）-3-（p-phenylethynylphenyl）-1,3-propanedione （HTPP） and 1-（2-furyl）-3-（p-phenylethynylphenyl）-1,3-propanedione （HFPP）, were synthesized by Sonogashira coupling reaction and Claisen condensation. Three new ternary rare earth complexes, TbL3phen （L = PPP, TPP, or FPP）, were synthesized by the reaction of rare earth chloride TbCl3,1,10-phenanthroline （phen） with HPPP, HTPP, or HFPP respectively, in alcohol solution. The compositions were characterized by means of elemental analysis, chemical analysis, and IR spectra. Luminescent properties of the three new complexes have been studied. The results show that the ternary Yb（Ⅲ） complexes only emit the weak fluorescence of the Tb（Ⅲ） ion, which reveals the triplet state energy of the ligands does not match well with the excited state vibrating energy of Tb^3＋ ion.

Synthesis of Eu(Ⅲ) and Tb(Ⅲ) Complexes with New Aryl Amide Type Tetrapodal Ligand and Their Luminescence Properties

A new aryl amide type tetrapodal ligand L (1, 1, 1, 1 tetrakis-{[(2 benzylaminoformyl) phenoxyl]methyl}methane) and its europium and terbium nitrate complexes were synthesized. The luminescence properties of these complexes were also studied.

Sol-Gel Preparation and Luminescence Properties of BaMgAl_(10)O_(17):Eu^(2+) Phosphors

The synthesis of BaMgAl10O17： Eu^2＋ （BAM） phosphors using the sol-gel method and their luminescence properties were reported. The blue-light emitting BAM was synthesized using citric acid and ethylene glycol as chelating materials. Emission of blue-light was obtained from these phosphors. The luminescent intensity increases as the temperature of heat treatment is increased, This study investigated the effects of the molar ratio of ethylene glycol to citric acid （Ф value）, with respect to the phase formation and luminescence properties of BAM. The variation of the Фvalue resulted in the change of the sol-gel reaction mechanism and the microstructures of the resultant powders. An increase in Фvalue leads to an increase in the rate of BAM phase formation. The photoluminescent intensity of the prepared phosphors increases with heating temperatures because of enhanced crystallization.

Synthesis and luminescence properties of rare earth ternary complexes consisting of Eu(III), β-diketones and 1,10-phenanthroline

Three novel β-diketones （HPPP, HTPP, and HFPP） ligands were synthesized by Sonogashira coupling reaction and Claisen condensation. The structure of β-diketones was confirmed with elemental analysis, IR, NMR and MS spectra. Three new ternary complexes consisting of Eu（Ⅲ）, β-diketones, and 1,10-phenanthroline（phen） were synthesized and characterized as TbL3phen （L=PPP, TPP, FPP） with elemental analysis, chemical analysis, and IR spectra, and their luminescence properties were studied.

Syntheses, Structures, and Luminescence Properties of Two New Open-framework Zinc Phosphites Based on 1,2,4-Triazole Derivatives

With 1,2,4-triazole derivatives as structure directing agents, two new openframework zinc phosphites, [Zn（atrz）（HPO3）]n（1） and [Zn（dmatrz）（HPO3）]n（2）（atrz = 4-amino-1,2,4-triazole, dmatrz = 4-amino-3,5-dimethyl-1,2,4-triazole） have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder and single-crystal X-ray diffractions. Both compounds are isostructure and crystallize in the P21/c space group of monoclinic system. Compound 1： a = 9.629（1）, b = 7.384（1）, c = 10.274（1） A, β = 110.729（3）°, V = 683.26（2） A^3, Z = 4, Mr = 229.44, Dc = 2.230 g/cm^3, F（000） = 456, S = 1.10, μ = 3.79 mm^（–1）, R = 0.0181 and w R = 0.0466 for 1121 observed reflections（（40） 〉 2s（（40）））. Compound 2： a = 10.786（2）, b = 8.921（1）, c = 9.749（1） A, β = 107.3°, V = 895.6（3） A^3, Z = 4, Mr = 257.49, Dc = 1.910 g/cm^3, F（000） = 520, S = 1.00, μ = 2.90 mm^（–1）, R = 0.018 and wR = 0.051 for 1581 observed reflections（（40） 〉 2s（（40）））. Both compounds are built up into 4.8-net 2D open-frameworks of vertex-linked Zn O4 and HPO3 units（3.57 × 4.53 A^2 for 1 and 4.43 × 5.90 A^2 for 2）. The structures consist of left-, right-handed helical chains that are connected through oxygen atoms to form an undulated 2D sheet stack, which can be topologically regarded as 4.8~2 nets. Solid-state luminescence properties and thermo gravimetric analyses of these two compounds were investigated, respectively.

Cd/Mn(Ⅱ) Complexes with Heterocyclic Substituted 1,2,4-Triazole Ligands：Syntheses,Crystal Structures,and Luminescence Properties

Based on a 3-（pyridine-2-yl）-4H-1,2,4-triazole ligand（Hpytr）, one 2D Cd（Ⅱ） coordination polymer [Cd I（pytr）]n（1） and one 2D Mn（Ⅱ） coordination polymer [Mn（N3）（pytr）（H2O）]n（2） have been synthesized and characterized by X-ray crystallography, elemental analysis, and fluorescence spectroscopy. 1 shows a layer coordination architecture linked by pytr ligand, and the Cd（Ⅱ） centers display slightly distorted square pyramid coordination geometries. Complex 2 shows a 2D pillared-layer coordination architecture bridged by N3-and pytr, and the Mn（Ⅱ） centers display slightly distorted octahedral geometries. The luminescent properties of 1 and the PXRD and thermal stability of complexes 1 and 2 were measured briefly.

Synthesis, Crystal Structure and Luminescence Properties of a Cadmium(Ⅱ) Complex Based on 2-Hydroxy-6-methylisonicotinic Acid

A new cadmium（Ⅱ） complex[Cd（Hminic）（IP）]n（1,Hminic = 2-hydroxy-6-methylisonicotinic acid,IP = imidazo[4,5-f]-l,10-phenanthroline）,has been synthesized by the reaction of a Hminic and auxiliary N-containing ligands with Cd（Ⅱ） ion under hydrothermal conditions.The complex was studied by elemental analysis,IR spectroscopy and X-ray crystallography.It is formulated as C（20）H（13）CdN5O3,crystallizes in monoclinic system,space group C2/c with α=9.6764（8）,b = 26.767（2）,c = 14.1332（11） A and β= 97.4510（10）°.V= 3629.7（5） A^3,Z = 8,Mr=483.75,Dc = 1.770 g/cm^3,F（000） = 1484 and μ= 1.237 mm^（-1）.The final refinement gave R = 0.0309 and wR = 0.0703 for 4151 reflections with I 〉2σ（I）.In the structure of 1,two Cd（Ⅱ） atoms are joined by a pair of μ2-hydroxyl oxygen atoms giving rise to a dinuclear Cd（Ⅱ） unit which is bridged by Hminic linkers to form a 1D ladder-like polymer chain.The chelating ligand IP coordinated to the Cd（Ⅱ） atom,and alternately attached to both sides of the ladder-like polymer chain.Adjacent chains are further bound together by strong intermolecular hydrogen bonds and face-to-face π…πinteractions,resulting in the formation of a 3D supramolecular architecture.Furthermore,the thermal stability and luminescent properties of this complex and the free ligands have been investigated.

Luminescence Properties of Phosphate Phosphor: Barium Tungstate Doped with Dy

A series of barium-tungstate-based phosphors doped with different concentrations of Dy3+ were synthesized by solid-state reaction method. Photoluminescence properties and decay lifetime of Dy3+-doped BaWO4 samples were studied. The results indicated that luminescent properties of BaWO4:Dy3+ depended on the Dy3+ concentration, and the inner energy could transfer from to Dy3+. The quality of the light was checked by estimating CIE parameters, and the results showed that BaWO4:Dy3+ was a potential candidate as blue-green luminescent materials in white LED because of its excellent emission spectrum excited by UV light.

Preparation and luminescence properties of Eu^(2+)-doped CASN-sinoite multiphase system for LED

A series of Eu2+-doped CASN-sinoite multiphase system with a formula of(CaAlSiN3)(1-x)-(Si2N2O)x were successfully synthesized by the high temperature solid-state method.The crystal structure and morphology of the phosphors and their photoluminescence(PL) were investigated.For the Eu2+-doped samples the PL intensity approached its maximum when the molar ratio of Si2N2O in the samples was about 0.15.With increase of the concentration of Si2N2O,the emission peak shifted from 645 to 605 nm.It was because the spectroscopic polarizability(αsp) became smaller with the increase of Si/Al ratio or the adding of O atoms,which caused the change of crystal field strength.In addition,the full width at half maximum(FWHM) widened with the increase of x value,which was favor of the improvement of the color rendering index.