Barium molybdate up-conversion nanoscale particles with IR-LED chip, temperature sensing, and anti-counterfeiting applications.

Barium molybdate nanoparticles exhibiting up-conversion luminescence were synthesized via the solvothermal method. Analysis revealed a prominent signal corresponding to the (112) plane in the XRD pattern, indicating the tetragonal structure of the synthesized nanoparticles. Raman spectroscopy detected the symmetric stretching frequencies of MoO4. When excited at 980 nm, the nanoparticles emitted a green spectrum with peaks at 532 and 553 nm. The luminescence intensity varied with the excitation light source, supporting the mechanism involving energy transfer from Yb-doped Er ions via the two-photon effect of the up-conversion phosphor. Moreover, the synthesized nanoparticles exhibited diminished luminous intensity with increasing temperature, suggesting potential for flexible composite sensor fabrication. Integration with a 980 nm LED chip yielded a green emission color. Furthermore, when applied to banknotes, plastic cards, fabrics, and artwork, the opaque solution mixed with polymers remained invisible to the naked eye; however, under 980 nm laser irradiation, the distinct green color became apparent, offering a viable approach for anti-counterfeiting measures.

Lignin-derived carbon quantum dot/PVA films for totally blocking UV and high-energy blue light.

Excessive exposure to UV and high-energy blue light (HEBL) can cause fatal eye and skin injuries. As a result, it is crucial to protect our bodies from UV and HEBL radiation. To achieve complete blocking of UV and HEBL, we developed a lignin-derived carbon quantum dot (L-CQD)/polyvinyl alcohol (PVA) film. L-CQD was synthesized from lignin, a waste woody biomass, and then blended with a PVA matrix to create a flexible L-CQD/PVA film. Thanks to simultaneous UV and HEBL absorption characteristics and bright color of L-CQD, the PVA film with 0.375 wt% L-CQD demonstrated outstanding blocking efficiency: 100 % in UV-C, UV-B, and UV-A, and at least 99.9 % in HEBL. It also exhibited a 44 % increase in lightness and a 12 % enhancement in transparency compared to lignin/PVA film. The film's ability to block UV and HEBL was further demonstrated by reducing >40 % UV-induced ROS formation in both cancerous and normal cell lines (Hs 294T, HeLa, CCD-986sk, and L929), as well as by blocking blue laser diode (LD) and LED. Since the L-CQD/PVA film is simple to produce, environmentally friendly, flexible, and thermally stable, it is suitable for use as a protective coating against sunlight and harmful emissions from IT devices.

Improvement of luminescence properties of NaYF4 :Yb3+ /Er3+ upconversion materials by a cross-relaxation mechanism based on co-doped Ho3+ ion concentrations.

NaYF4 :Yb3+ /Er3+ /Ho3+ nanophosphors were successfully synthesized using a solvothermal method and with various concentrations of Ho3+ ions. The crystal structure, grain size, morphology, and luminescence properties were analyzed by X-ray diffraction, field-emission scanning electron microscopy, and photoluminescence measurements. All samples were crystallized as a cubic structure; it was confirmed that all samples exhibited strong green emission and weak red emission generated at a particular level of the activated ions. The strongest upconversion fluorescence intensity was observed in the Ho3+ and Er3+ ions co-doped NaYF4 materials with a Ho3+ ion concentration of 0.005 mol. Only the green fluorescence intensity at the 542 nm centre increased strongly due to the 4 S3/2 →4 I15/2 energy transfer. This increase in upconversion fluorescence intensity at a selected wavelength was described as a cross-relaxation mechanism due to the addition of Ho3+ ions.

Biocompatible sphere, square prism and hexagonal rod Gd2O3:Eu3+@SiO2 nanoparticles: The effect of morphology on multi-modal imaging.

The cubic structure Gd2O3:Eu3+@SiO2 particles with homogeneous multiform morphologies (pH 6: sphere, pH 10: square prism and pH 12: hexagonal rod) were prepared by pH modifiers: nitric acid- and ammonium hydroxide-assisted solvothermal reaction. The effect of synthesis conditions (reaction time and pH value) on the morphology and the particle growth mechanisms were researched. The photoluminescence (PL), magnetic resonance imaging (MRI) and X-ray computed tomography (CT) studies of Gd2O3:Eu3+@SiO2 showed strong dependence on the morphology alteration. The longitudinal relaxivity value of Gd2O3:Eu3+@SiO2 was 10.24 (pH 6), 14.52 (pH 10) and 25.68 (pH 12) s-1 mM-1 at 3 T, which is equivalent to 2.4, 3.8 and 6.2 times higher than to the Dotarem (commercial clinical MRI contrast agent). Furthermore, the Gd2O3:Eu3+@SiO2 with different pH values (6, 10 and 12) has the good biocompatibility. This study provides the useful multifunctional contrast agents based on multiform Gd2O3:Eu3+@SiO2 particles.

Microwave-assisted sintering synthesis of greenish-yellow emitting Sr2 SiO4 :Eu2+ phosphors.

Europium ion (Eu2+ ) doped Sr2 SiO4 phosphors with greenish-yellow emission were synthesized using microwave-assisted sintering. The phase structure and photoluminescence (PL) properties of the obtained phosphor samples were investigated. The PL excitation spectra of the Sr2 SiO4 :Eu2+ phosphors exhibited a broad band in the range of 260 nm to 485 nm with a maximum at 361 nm attributed to the 5f-4d allowed transition of the Eu2+ ions. Under an excitation at 361 nm, the Sr2 SiO4 :Eu2+ phosphor exhibited a greenish-yellow emission peak at 541 nm with an International-Commission-on-Illumination (CIE) chromaticity of (0.3064, 0.4772). The results suggest that the microwave-assisted sintering method is promising for the synthesis of phosphors owing to the decreased sintering time without the use of additional reductive agents.

Synthesis and Luminescent Properties of Gd2MoO6:Eu(3+).

A series of 6 mol% Eu(3+) doped Gd2MoO6 samples were prepared by using the sol-gel method. The X-ray diffraction patterns of the samples confirmed their monoclinic structure after they were annealed at 1300 °C, and a scanning electron microscope image revealed closely packed particles. The excitation spectra showed that the intensity of the excitation band decreased and the charge transfer band shifted from 370 to 350 nm with decreasing sintering temperature. The emission spectra are dominated by the hypersensitive forced electron dipolar transition (5)D0 --> (7)F2 at 612 nm. The as synthesized phosphor can be used as a red phosphor in white light emitting diodes.

Synthesis and Luminescent Properties of Eu(3+) Doped CaGd4O7 Phosphors by Solvothermal Reaction Method.

Eu(3+) doped CaGd4O7 phosphors have been newly synthesized using a solvothermal reaction method and sintered at 1400 °C. The phase, composition, morphologies, and photoluminescent properties of the phosphors have been well characterized by means of the X-ray diffraction (XRD) patterns, energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectroscopy, and decay curves, respectively. The XRD patterns of the as-prepared phosphors confirm their monoclinic structure and the FE-SEM images reveal flower-like morphology, formed through agglomeration. The calculated size of the crystallites was approximately 83 nm. The photoluminescence excitation (PLE) spectra of CaGd4O7:Eu(3+) phosphors consist of a broad band due to the charge transfer (CT) electronic transition, and several sharp peaks that can be attributed to the f-f transitions of Eu(3+) and Gd(3+). The PL spectra exhibited a stronger red emission corresponding to the (5)D0 --> (7)F2 transition. The CIE chromaticity coordinates of the phosphors were calculated and all the chromaticity coordinates have been placed in the red spectral region. These luminescent powders are expected to have potential applications for white light-emitting diodes (WLEDs) and optical display systems.

Hydrothermal synthesis and photoluminescence investigation of NaY(MoO4)2:Eu3+ nanophosphor.

An intense red-emitting NaY(MoO4)2:Eu3+ nanophosphor was developed using a hydrothermal technique. A highly pure and single-phase NaY(MoO4)2:Eu3+ nanopowder was obtained after sintering the as-prepared sample at 800 degrees C. The crystal structure and photoluminescence properties of this double molybdate were investigated. X-ray diffraction analysis showed that the NaY(MoO4)2 nanoparticles have a scheelite-type tetragonal structure, without mixed phases. Rietveld analysis provided the atomic coordinates and Mo-O-rare-earth angles. The morphology of the molybdate precursor was controlled by adjusting the synthesis conditions. The pH was found to play a crucial role in the particle size and morphology distribution. The crystalline powder phosphor exhibited intense and efficient red emissions attributed to efficient energy-transfer from MoO4(2-) to Eu3+. The chromaticity coordinates (x,y) of the NaY(MoO4)2:Eu3+ phosphor sample correspond to (0.662, 0.337). The NaY(MoO4)2:Eu3+ powder exhibited a deep-red emission under near-ultraviolet (UV) excitation, indicating a promising red phosphor for white-light-emitting diodes based on near-UV light-emitting diodes.

Crystal growth and photoluminescence properties of Sm3+ doped CeO2 nanophosphors by solvothermal method.

The phosphor of CeO2 activated with the trivalent rare-earth Sm3+ ions were synthesized by using a solvothermal method. The CeO2:Sm3+ powders were finally obtained through calcination process sintered in the air at 800-1200 degrees C. The synthesized phosphors were characterized systematically by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) and photoluminescence excitation spectra (PLE). The XRD and FE-SEM results reveal that the phosphor exhibit agglomerated spherical shape and with the increase of sintering temperature peaks become sharper and narrower and the crystal sizes also increase, respectively. The room temperature photoluminescence spectra of Sm3+ doped CeO2 powders were recorded on a PTI (Photon Technology International) flurimeter using a Xe-arc lamp with a power of 60 W. The emitted radiation was dominated by the orange light with the characteristic emission of Sm3+ from the transitions of 4G5/2 --> 6H5/2,7/2. The sharp emission properties show that the CeO2 has the potential to serve as a host material for rare-earth doped laser crystal and phosphor material.

Concentration enhanced upconversion luminescence in ZrO2:Ho3+, Yb3+ nanophosphors.

The upconversion luminescence properties of ZrO2:Ho3+ and co-doped ZrO2:Ho3+, Yb3+ nanophosphors with various concentrations of Yb3+ ions were synthesized via a solvothermal reaction method. Our samples have a nearby spherical shape and an average crystal size was about 80 nm. For low concentrations of Yb3+ ion, the crystalline structure changed from tetragonal to monoclinic phase as the Yb3+ concentration increased to 3 mol% Yb3+ ions. As the Yb3+ concentration increased to above 5 mol%, ZrO2 nanophosphors displayed a very stable tetragonal phase. The sample shows a strong green (550 nm) and weak red (660 nm) and near infrared (757 nm) upconversion emission corresponding to the transitions of Ho3+:5F4/5S2 --> 5I8, 5F5 --> 5I8 and 5S2 --> 5I7, respectively. The energy transfer (ET) processes between the Ho3+ and Yb3+ ions and the involved mechanisms have been investigated. Experimental results suggest that two-photon upconversion processes are taking place under excitation by a 975 nm.

Luminescence characteristics of Pr3+ ion doped CaTiO3 nanopowder phosphors synthesized by solvothermal method.

In display applications, each displays technique needs different phosphors according to its applications. So, in this paper, nano-sized red emitting CaTiO3:Pr3+ powder phosphors were prepared by solvothermal reaction method. The phase purity and the structure of the phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM). The particles show the spherical morphology, which indicates the good luminescent characteristics. The luminescent properties of CaTiO3:Pr3+ powder phosphors have been carried out by the measurement of their phototluminescence (PL) and phototluminescence excitation (PLE) spectra. The PL spectra shows the strong red emission due to 1D2 --> 3H4 transition. The emissions of intra-4f transitions from the excited states (1D2) to the ground state (3H4) of Pr3+ are mainly observed around from 612 to 618 nm. The effect of the Pr3+ concentration on their photoluminescent properties was investigated extensively. These luminescent powders are expected to find potential applications such as optical display systems.

Crystal structure, electronic structure, and optical and photoluminescence properties of Eu(III) ion-doped Lu6Mo(W)O12.

Lu(6)WO(12) and Lu(6)MoO(12) doped with Eu(3+) ions have been prepared by using a citrate complexation route, followed by calcination at different temperatures. The morphology, structure, and optical and photoluminescence properties of the compounds were studied as a function of calcination temperature. Both compositions undergo transitions from a cubic to a hexagonal phase when the calcination temperature increases. All the compositions have strong absorption of near-UV light and show intense red luminescence under a near-UV excitation, which is related to the transfer of energy from the host lattices to dopant Eu(3+) ions. Density functional theory calculations have also been performed. The calculation reveals that hexagonal Lu(6)WO(12) and Lu(6)MoO(12) are indirect bandgap materials, and the near-UV excitations are due to the electronic transitions from the O-2p orbitals to W-5d and Mo-4d orbitals, respectively. The lattice parameters and bandgap energies of hexagonal Lu(6)WO(12) and Lu(6)MoO(12) were determined.

Hydrothermal synthesis and optical properties of Eu(3+)-doped CaSnO3 nanocrystals.

In this paper, CaSnO3:Eu3+ nanocrystals were prepared by hydrothermal synthesis method. The influence of different molar ratio of Ca:Sn on structure of CaSnO3:Eu3+ was investigated by using X-ray powder diffraction (XRD). Well-crystallized and phase-pure CaSnO3:Eu3+ particles of approximately 90 nm in size can be readily obtained at 900 degrees C. Furthermore, photoluminescence characterization of the Eu(3+)-doped CaSnO3 nanocrystals was performed and discussed. The emission peak situated at 618 nm showing prominent and bright red light is due to the 5D0-7F2 electric dipole transition. The excellent luminescence properties make it possible as a good candidate for PDP application.

Controlled fabrication and shape-dependent luminescence properties of hexagonal NaCeF4, NaCeF4:Tb3+ nanorods via polyol-mediated solvothermal route.

Hexagonal monodisperse NaCeF(4) and NaCeF(4):Tb(3+) nanorods have been successfully synthesized by a polyol-mediated solvothermal route with ethylene glycol (EG) as solvent. The crystalline phase, size, morphology, and luminescence properties were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra as well as dynamic decays. The experimental results indicate that the content of NH(4)F and NaNO(3) are crucial in controlling product morphology and size. Nanorods with different aspect ratios could be controllably obtained under settled conditions. Shape-dependent luminescence and energy transfer routes from Ce(3+) to Tb(3+) in NaCeF(4):Tb(3+) nanorods were observed by the modified local crystal field environment around rare earth ions. The 4f-5d transitions of Ce(3+) ions have much higher sensitivity to the anisotropic shape of samples than that of Tb(3+) ions.

Structure, charge transfer bands and photoluminescence of nanocrystals tetragonal and monoclinic ZrO2:Eu.

Eu(3+)-doped tetragonal and monoclinic ZrO2 (called t-ZrO2:Eu and m-ZrO2:Eu, respectively) nanoparticles were prepared using the Pechini sol-gel process. The samples were characterized via X-ray diffraction (XRD) and field-emission-scanning electron microscopy (FE-SEM), and with photoluminescence spectra. The influences of the Eu3+ concentration and the fired temperature on the crystal phase composition of the tetragonal and monoclinic ZrO2:Eu were reported. The typical interesting photoluminescence (PL) properties of the t-ZrO2:Eu and m-ZrO2:Eu nanoparticles were presented. In the t-ZrO2:Eu and m-ZrO2:Eu, the main emission peaks were at 607 and 615 nm, respectively, both of which originated from the 5D0-7F2 transition. The excitation band of the t-ZrO2:Eu powder with a lower Eu3+ doping concentration that was obtained at a low temperature (450 degrees C) consisted of a broad band of 230-500 nm. Both broad excitation bands in the t-ZrO2:Eu and m-ZrO2:Eu were ascribed to the O(2-) - Eu3+ charge transfer (CT) transition. The reason was discussed based on the relationship between the CT energy and its crystal structure. The CT energy of m-ZrO2:Eu is higher than that of t-ZrO2:Eu. A detailed chemical bond analysis was performed to explore the CT energy difference between t-ZrO2: Eu and m-ZrO2:Eu.

Synthesis and luminescence properties behavior of Eu(3+)-doped nanocrystalline and bulk GdVO4 phosphors by high-energy ball milling and solid state reaction.

Europium-doped nanosized-GdVO4:Eu3+ powders and bulk GdVO4:Eu3+ powders were synthesized using a planetary ball mill and conventional solid state reaction method, respectively. The effects of the grain size on the crystallinity, morphology, structure and luminescence spectra were investigated by X-ray diffraction, field emission-scanning electron microscopy and photoluminescence spectroscopy (PL). The room temperature PL spectra of the GdVO4:Eu3+ nanophosphors showed four emission bands at 611, 615, 619 and 595 nm. The bands at 611, 615 and 619 nm were assigned to the 5D0 --> 7F2 transition of the EU3+ ion when excited with 312 nm light.

Luminescent properties of SrZnO2:Tb3+ hybrid thin film phosphors grown by pulsed laser deposition.

Novel green-light-emitting Tb(3+)-doped SrZnO2 phosphor thin films were grown via the pulsed-laser-deposition technique. The films were grown at various substrate temperatures and oxygen pressures. The crystallinity and surface morphology of the films were investigated via X-ray diffraction (XRD) and atomic-force microscopy (AFM), respectively. The luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. The thin films showed a green emission radiated by the transitions from the 5D4 excited states to the 7FJ (J = 3-6) ground states of the Tb3+ ions found under ultraviolet excitation with a 272 nm wavelength. The crystallinity, surface morphology, and photoluminescence spectra of thin-film phosphors were found to be highly dependent on the deposition conditions, particularly the substrate temperature and oxygen pressure. The surface roughness and photoluminescence intensity of the films showed similar behaviors as a function of the substrate temperature and oxygen pressure.

Low-temperature synthesis of CaTiO3 nanocrystals doped with Pr3+ ions and their luminescence.

CaTiO3:Pr3+ nanocrystals were synthesized by solvothermal method. The as-prepared powders crystallized to the pure orthorhombic phase after calcination at 600 degrees C in air for 3 hours. CaTiO3:Pr3+ nanocrystals are petaline in shape with the decrease of the reactant concentration. The corresponding bulk CaTiO3:Pr3+ was synthesized by high temperature solid-state reaction. All the products were systematically characterized by powder X-ray diffraction (XRD), infrared spectroscopy (IR), field emission-scanning electron microscopy (FE-SEM), diffuse reflectance spectra (DRS), photoluminescence (PL) and photoluminescent excitation spectra (PLE). The luminescence mechanism and the size dependence of their fluorescence properties are also discussed.

Application of column-switching HPLC method in evaluating pharmacokinetic parameters of zaltoprofen and its salt.

The objective of this study was to compare the pharmacokinetic parameters of zaltoprofen and those of its sodium salt in rats. Zaltoprofen, a potent non-steroidal anti-inflammatory agent, was virtually insoluble in water, but its sodium salt had excellent water solubility. To investigate the effect of aqueous solubility differences upon their pharmacokinetic parameters, minicapsules containing the drug powders were administrated orally to rats, and blood samples were taken via the common carotid artery. A column-switching high-performance liquid chromatographic analytical procedure was developed and validated for the quantitation of zaltoprofen in rat plasma samples. Our study demonstrated that the time required to reach maximum plasma concentration (T(max)) of zaltoprofen sodium was significantly reduced and its maximum plasma concentration (C(max)) was increased 1.5-fold, relative to the values for zaltoprofen. It is anticipated that the sodium salt of zaltoprofen will allow the rapid onset of the drug's action in the treatment of inflammatory diseases.