Facile sonochemical synthesis and photoluminescent properties of lanthanide orthophosphate nanoparticles

Uniform lanthanide orthophosphate LnPO(4) (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho) nanoparticles have been systematically synthesized via a facile, fast, efficient ultrasonic irradiation of inorganic salt aqueous solution under ambient conditions 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), photoluminescence (PL) spectra as well as kinetic decays were employed to characterize the samples. The SEM and the TEM images show that the hexagonal structured lanthanide orthophosphate LnPO(4) (Ln = La, Ce, Pr, Nd. Sm, Eu, Gd) products have nanorod bundles morphology, while the tetragonal LnPO(4) (Ln = Tb, Dy, Ho) samples prepared under the same experimental conditions are composed of nanoparticles. HRTEM micrographs and SAED results prove that these nanostructures are polycrystalline in nature.

SrF2 hierarchical flowerlike structures: Solvothermal synthesis, formation mechanism, and optical properties

We present a solvothermal route to the synthesis of SrF2 hierarchical flowerlike structures based on thermal decomposition of single source precursor (SSP) of strontium trifluoroacetate in benzylamine solvent. These flowerlike superstructures are actually composed of numerous aggregated nanoplates, and the growth process involves the initial formation of spherical nanoparticles and subsequent transformation into nanoplates. which aggregated together to form microdisks and finally flowerlike superstructures. The results demonstrate the important role of benzylamine in the formation of well-defined SrF2 superstructures, not only providing size and shape control to form nanoplates but also contributing to the self-assembly behavior of nanoplates to build into flower-like superstructures. Additionally, the photoluminescence properties of the obtained SrF2 superstructures are studied.

Synthesis and characterization of magnetic FexOy@SBA-15 composites with different morphologies for controlled drug release and targeting

Magnetic functionalization of the ordered mesoporous SBA-15 (SiO2) aggregate blocks and rice grain-like particles were realized by using a sol-gel method, resulting in the formation of FexOy@SBA-15 composite materials. The X-ray diffraction (XRD), N-2 adsorption/desorption, and transmission electron microscopy (TEM) results show that these composites conserved ordered mesoporous structure after the formation of FexOy nanoparticles in the pores and on the outer surface of SBA-15. It was confirmed by the XRD and X-ray photoelectron spectroscopy (XPS) analysis that the FexOy generated in these mesoporous silica hosts is mainly composed of gamma-Fe2O3. Magnetic measurements reveal that these composites possess superparamagnetic properties at 300 K. The saturation magnetization of these composites increased with the increasing loading amount of gamma-Fe2O3. These composites, which possess high surface area and high pore volume, show magnetic response sufficient for drug targeting in the presence of an external magnetic field.

Direct synthesis of ordered N-methylimidazolium functionalized mesoporous silica as highly efficient anion exchanger of Cr(VI)

Ordered N-methylimidazolium functionalized mesoporous silica (SBA-15) anion exchangers were directly synthesized by co-condensation of tetraethoxysilane with 1-methyl-3(triethoxysilylpropyl)imidazolium chloride. The prepared samples with rod-like morphology showed high surface areas (> 400 m(2) g(-1)), well-ordered pores (> 58 angstrom), and excellent thermal stability up to 387 degrees C. The adsorption behaviors of Cr(VI) from aqueous solution on the anion exchangers were studied using the batch method. The anion exchangers had high adsorption capacity ranging from 50.8 to 90.5 mg g(-1), over a wider pH range (1-8) than amino functionalized mesoporous silica. The adsorption rate was fast, and the maximum adsorption was obtained at pH 4.6. The adsorption data for the anion exchangers were consistent with the Langmuir isotherm equation. Most active sites of the anion exchangers were easily accessible. The mixed solution of 0.1 mol L-1 NH3 center dot H2O and 0.5 mol L-1 NH4Cl was effective desorption solution, and 95% of Cr(VI) could be desorbed.

Facile synthesis of highly uniform octahedral LuVO4 microcrystals by a facile chemical conversion method

Uniform octahedral LuVO4 microcrystals have been successfully prepared through a designed two-step hydrothermal method. One-dimensional lutetium precursor was first prepared through a simple hydrothermal route. Subsequently, a well-shaped octahedral LuVO4 sample was synthesized at the expense of the wirelike precursors during the hydrothermal process. The whole process in this method was carried out in aqueous conditions without the use of any organic solvents, surfactant, or catalyst. The conversion process from nanowire precursor to octahedral product has been investigated in detail. The LuVO4 : Ln(3+) (Ln Eu, Dy, Sm, and Er) phosphors show strong light emissions with different colors coming from different activator ions under ultraviolet light excitation or low-voltage electron beam excitation. Furthermore, this general and facile method may be of much significance in the synthesis of many other lanthanide compounds with polyhedral morphology.

Effect of Single- and co-Dopant on TL of Sr2Mg(BO3)(2) Phosphor

Sr2Mg(BO3)(2) thermoluminescence (TL) phosphor was synthesized by a high temperature solid state reaction and the effect of Li+, Bi3+, Gd3+ or Ti4+ as a codopant on TL of Sr2Mg(BO3)(2) : Dy was investigated. The results show that Li+ as a codopant improves the emission intensity of high temperature TL peak of Sr2Mg(BO3)(2) : Dy phosphor whereas the addition of Bi3+, Gd3+ or Ti3+ leads to the decrease of TL intensity. The TL emission bands of Sr2Mg(BO3)(2) : Dy phosphors with Li+, Bi3+, Gd3+ or Ti4+ as a codopant are situated at 480, 579, 662 and 755 nm, which were attributed to the characteristic F-4(9/2)-> H-6(15/2), F-4(9/2)-> H-6(13/2), F-4(9/2)-> H-6(11/2) and F-4(9/2)-> H-6(9/2) transitions of Dy3+ ion, consistent with the emission of Sr2Mg(BO3)(2) : Dy phosphors. The kinetics parameters of 234 degrees C TL peak of Sr2Mg(BO3)(2) Dy-0.04(3+), (Li-0.04(+)) phosphor with the values of trap depth E=1.1 eV, frequency factor s=6.3 x 10(9) s(-1) were estimated by a peak shape method, which obey the second order kinetics.

Effect of Single- and co-Dopant on TL of Sr2Mg(BO3)(2) Phosphor(单掺杂与共掺杂离子对Sr_2Mg(BO_3)_2磷光体热释发光的影响)

Sr2Mg(BO3)(2) thermoluminescence (TL) phosphor was synthesized by a high temperature solid state reaction and the effect of Li+, Bi3+, Gd3+ or Ti4+ as a codopant on TL of Sr2Mg(BO3)(2) : Dy was investigated. The results show that Li+ as a codopant improves the emission intensity of high temperature TL peak of Sr2Mg(BO3)(2) : Dy phosphor whereas the addition of Bi3+, Gd3+ or Ti3+ leads to the decrease of TL intensity. The TL emission bands of Sr2Mg(BO3)(2) : Dy phosphors with Li+, Bi3+, Gd3+ or Ti4+ as a codopant are situated at 480, 579, 662 and 755 nm, which were attributed to the characteristic F-4(9/2)-> H-6(15/2), F-4(9/2)-> H-6(13/2), F-4(9/2)-> H-6(11/2) and F-4(9/2)-> H-6(9/2) transitions of Dy3+ ion, consistent with the emission of Sr2Mg(BO3)(2) : Dy phosphors. The kinetics parameters of 234 degrees C TL peak of Sr2Mg(BO3)(2) Dy-0.04(3+), (Li-0.04(+)) phosphor with the values of trap depth E=1.1 eV, frequency factor s=6.3 x 10(9) s(-1) were estimated by a peak shape method, which obey the second order kinetics.

Photoinduced DNA Cleavage by alpha-, beta-, and gamma-Cyclodextrin-Bicapped C-60 Supramolecular Complexes

Water-soluble supramolecular inclusion complexes of alpha-, beta-, and gamma-cyclodextrin-bicapped C-60 (CD/C-60) have been investigated for their photoinduced DNA cleavage activities, with the aim to assess the potential health risks of this class of compounds and to understand the effect of host cyclodextrins having different cavity dimensions. Factors such as incubation temperature, irradiation time, and concentration of NADH or CDs/C-60 supramolecular inclusion complexes have been examined. The results show that alpha-, beta-, and gamma-CDs/C-60 are all able to cleave double-stranded DNA under visible light irradiation in the presence of NADH. However, a difference in the photoinduced DNA cleavage efficiency is observed, where the cleavage efficiency increases in the order of alpha-, beta-, and gamma-CD/C-60. The difference is attributed to the different aggregation behavior of the inclusion complexes in aqueous solution, which is correlated to the cavity dimension of the host cyclodextrin molecules.

电感耦合等离子体质谱法测定高纯氧化钕中的稀土杂质

基于电感耦合等离子体四极杆质谱仪进行Nd2O3中稀土杂质测定,着重研究了碰撞反应池技术(CCT)用于基体Nd氧化物和氢氧化物干扰离子的消除。研究表明,以10%O2-10%Ar-80%He为碰撞反应气,保持反应气流速为0.1 mL/min,并通过调谐仪器参数,获得159Tb,165Ho,163Dy同位素的175TbO,179DyO和181HoO出现强氧化物峰,通过对这些氧化物离子进行检测而实现Tb,Dy,Ho的定量分析。在优化的条件下,基体导致的氧化物和氢氧化物质谱干扰可降低25～70倍。研究了CCT模式下不同内标元素用于基体效应的校正。结果表明,Re的校正效果最佳。其余La,Ce,Pr,Sm,Eu,Gd,Er,Tm,Yb和Lu等元素采用常规模式测定,其中Pr的测定采用高分辨以消除基体Nd前沿峰干扰。结合干扰系数校正,所建立的方法适用于99.999%Nd2O3的纯度分析,RSD小于5%,加入回收率令人满意。

Different microstructures of ss-NaYF4 fabricated by hydrothermal process: Effects of pH values and fluoride sources

beta-NaYF4 microcrystals with a variety of morphologies, such as microrod, hexagonal microprism, and octadecahedron, have been synthesized via a facile hydrothermal route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) spectra were used to characterize the samples. The intrinsic structural feature of beta-NaYF4 seeds and two important external factors, namely, the pH values in the initial reaction solution and fluoride sources, are responsible for shape determination of beta-NaYF4 microcrystals. It is found that the organic additive trisodium citrate (Cit(3-)) as a shape modifier has the dynamic effect by adjusting the growth rate of different facets under different experimental conditions, resulting in the formation of the anisotropic geometries of various beta-NaYF4 microcrystals. The possible formation mechanisms for products with various architectures have been presented. A systematic study on the photoluminescence of Tb3+-doped beta-NaYF4 samples with rod, prism, and octadecahedral shapes has shown that the optical properties of these phosphors are strongly dependent on their morphologies and sizes.

Y2O3 : Eu3+ microspheres: Solvothermal synthesis and luminescence properties

Y2O3 : Eu3+ microspheres, with an average diameter of 3 mu m, were successfully prepared through a large-scale and facile solvothermal method followed by a subsequent heat treatment. X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectra, thermogravimetric and differential thermal analysis, inductive coupled plasma atomic absorption spectrometric analysis, scanning electron microscopy, transmission electron microscopy, photoluminescence spectra, as well kinetic decays, and cathodoluminescence spectra were used to characterize the samples. These microspheres were actually composed of randomly aggregated nanoparticles. The formation mechanisms for the Y2O3 : Eu3+ microspheres have been proposed on an isotropic growth mechanism. The Y2O3 : Eu3+ microspheres show a strong red emission corresponding to D-5(0) -> F-7(2) transition (610 nm) of Eu3+ under ultraviolet excitation (259 nm) and low-voltage electron beams excitation (1-5 kV), which have potential applications in fluorescent lamps and field emission displays.

Luminescence functionalization of SBA-15 by YVO4 : Eu3+ as a novel drug delivery system

Luminescence functionalization of the ordered mesoporous SBA-15 silica was realized by depositing a YVO4:Eu3+ phosphor layer on its surface via the Pechini sol-gel process, resulting in the formation of the YVO4:Eu3+@SBA-15 composite material. This material, which combines the mesoporous structure of SBA-15 and the strong red luminescence property of YVO4:Eu3+, can be used as a novel functional drug delivery system. The structure, morphology, porosity, and optical properties of the materials were well characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N-2 adsorption, and photoluminescence spectra. As expected, the pore volume, surface area, and pore size of SBA-15 decrease in sequence after deposition of the YVO4:Eu3+ layer and the adsorption of ibuprofen (IBU, drug). The IBU-loaded YVO4:Eu3+@SBA-15 system still shows the red emission of Eu3+ (617 nm, D-5(0)-F-7(2)) under UV irradiation and the controlled drug release property. Additionally, the emission intensity of Eu3+ increases with an increase in the cumulative released amount of IBU in the system, making the extent of drug release easily identifiable, trackable, and monitorable by the change of luminescence. The system has great potential in the drug delivery and disease therapy fields.

Monodisperse and core-shell-structured SiO2@YBO3 : Eu3+ spherical particles: Synthesis and characterization

Y0.9Eu0.1BO3 phosphor layers were deposited on monodisperse SiO2 particles of different sizes (300, 570, 900, and 1200 nm) via a sol-gel process, resulting in the formation of core-shell-structured SiO2@Y0.9Eu0.1BO3 particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence (CL) spectra as well as lifetimes were employed to characterize the resulting composite particles. The results of XRD, FE-SEM, and TEM indicate that the 800 degrees C annealed sample consists of crystalline YBO3 shells and amorphous SiO2 cores, in spherical shape with a narrow size distribution. Under UV (240 nm) and VUV (172 nm) light or electron beam (1-6 kV) excitation, these particles show the characteristic D-5(0)-F-7(1-4) orange-red emission lines of Eu3+ with a quantum yield ranging from 36% (one-layer Y0.9Eu0.1BO3 on SiO2) to 54% (four-layer Y0.9Eu0.1BO3 on SiO2).

Biofunctionalization of CeF3 : Tb3+ nanoparticles

CeF3: Tb3+ nanoparticles (short pillar-like morphology with an average length and width of 11 and 5 nm, respectively) were successfully prepared by a polyol process using diethyleneglycol (DEG) as solvent. After being functionalized with a SiO2-NH2 layer, these CeF3: Tb3+ nanoparticles can be conjugated with biotin molecules (activated by thionyl chloride) and further with avidin. The as-formed CeF3: Tb3+ nanoparticles, CeF3: Tb3+ nanoparticles functionalized with amino groups, biotin conjugated amino-functionalized CeF3: Tb3+ nanoparticles and biotinylated CeF3: Tb3+ nanoparticles bonded with avidin were characterized by x-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), UV/vis absorption spectra and luminescence spectra, respectively. The biofunctionalization of the CeF3: Tb3+ nanoparticles has less effect on their luminescence properties, i.e. they still show strong green emission (from Tb3+, with D-5(4) - F-7(5) at 543 nm as the most prominent group), indicative of the great potential for these CeF3: Tb3+ nanoparticles to be used as biological fluorescence probes.

Spherical SiO2@GdPO4 : Eu3+ core-shell phosphors: Sol-gel synthesis and characterization

Nanocrystalline GdPO4 : Eu3+ phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by Pechini sol-gel method, resulting in the formation of core-shell structured SiO2@GdPO4 : Eu3+ particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), time-resolved PL spectra and lifetimes were used to characterize the core-shell structured materials. Both XRD and FT IR results indicate that GdPO4 layers have been successfully coated on the SiO2 particles, which can be further verified by the images of FESEM and TEM. Under UV light excitation, the SiO2@GdPO4: Eu3+ phosphors show orange-red luminescence with Eu(3+)sD(0)-F-7(1) (593 nm) as the most prominent group. The PL excitation and emission spectra suggest that an energy transfer occurs from Gd3+ to Eu3+ in SiO2@GdPO4: Eu3+ phosphors. The obtained core-shell phosphors have potential applications in FED and PDP devices.