Pechini Sol-gel Process Research Articles

Synthesis and Photoluminescence Properties of Monodisperse Spherical SiO<sub>2</sub>@Lu<sub>2</sub>O<sub>3</sub>: Eu<sup>3+</sup> Particles with Core-Shell Structure

Spherical submicron SiO2 particles have been coated with luminescent Lu2O3: Eu3+ layers by a Pechini sol-gel process, resulting in the formation of SiO2@Lu2O3: Eu3+ core-shell particles(300, 500 nm). The obtained core–shell phosphors have perfect spherical shape with narrow size distribution, smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (50 nm for four deposition cycles). Under the excitation of ultraviolet, the Eu3+ ion mainly shows its characteristic emissions in the core-shell particles from Lu2O3: Eu3+) shells. The PL intensity of Eu3+ increases with the number of coating cycles.

Synthesis and Luminescent Properties of Monodisperse Spherical SiO<sub>2</sub>/Ca<sub>10</sub>(PO<sub>4</sub>)<sub>6</sub>(OH)<sub>2</sub>: Eu<sup>3+</sup> Particles with Core-Shell Structure

The growing necessity of biomaterials has increased the interest in calcium phosphates, particularly hydroxyapatite. In this paper, monodisperse and spherical SiO2 particles have been coated with Ca10(PO4)6(OH)2:Eu3+ layers via a Pechini sol-gel process, resulting in core-chell ctructured SiO2/Ca10(PO4)6(OH)2:Eu3+ samples. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra were employed to characterize the SiO2/Ca10(PO4)6(OH)2:Eu3+ core-shell particles. The resulted core-shell particles have perfect spherical shape with narrow size distribution, smooth surface and non-agglomeration.

Synthesis and Characterization of Monodisperse Spherical SiO<sub>2</sub>@Y<sub>2</sub>O<sub>3</sub>: Tb<sup>3+</sup> Particles with Core-Shell Structure

Spherical submicron SiO2 particles have been coated with luminescent Y2O3: Tb3+ layers by a Pechini sol-gel process, resulting in the formation of SiO2@Y2O3: Tb3+ core-shell particles. The obtained core–shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 450 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (35 nm for two deposition cycles). Under the excitation of ultraviolet, the Tb3+ ion mainly shows its characteristic emissions in the core-shell particles from Y2O3: Tb3+) shells. The emission intensity of Tb3+ can be tuned by the annealing temperature and the number of coating cycles.

Luminescence properties of Lu3Al5O12:Tb3+ nano-garnet

Trivalent terbium-doped lutetium-aluminate nano-garnet (Lu3Al5O12:Tb3+) powder was prepared by using the Pechini sol-gel process. The structure and crystallinity of the Lu3Al5O12:Tb3+ nano-garnet were characterized by using X-ray diffraction, transmission electron microscopy and Fourier transform infrared spectroscopy. The green emission of Tb3+ ions is observed at 545 nm corresponding to the 5D4 → 7F5 transition under the 271-nm excitation. The temperature dependent luminescence properties of the Lu3Al5O12:Tb3+ nano-garnet are investigated. The results show that the present garnet exhibits better thermal stability than the other green emitting phosphors, hence, the Lu3Al5O12:Tb3+ phosphor is a promising candidate for light-emitting devices.

Energy transfer processes in Eu3+ doped nanocrystalline La2TeO6 phosphor

La2TeO6 nanocrystals doped with Eu3+ ions have been prepared by the Pechini sol–gel process. A total of seven samples obtained with different Eu3+ concentrations (1–7%). The Eu3+ ions are usually taken as probe ions to test the local structure of the lanthanide in solids. Analyzing the luminescence has been shown two different sites for the Eu3+ ions (in good agreement with the crystallographic analysis). Moreover, the luminescence properties have been analyzed as function of the Eu3+ doping concentration in order to study the interaction between these ions. Under direct excitation into the 5D0 level (at 578nm) the corresponding decay curves show a pure exponential character independently of the Eu3+ concentration. However, the decay curves obtained for the 5D1 level becomes non-exponential for the higher doped nanocrystals samples indicating that the energy transfer processes are important.

Long-lasting phosphorescence functionalization of mesoporous silica nanospheres by CaTiO3:Pr3+ for drug delivery

Long-lasting phosphorescence functionalization of the ordered mesoporous silica nanospheres (MSNs) was realized by depositing a CaTiO3:Pr3+ phosphor layer on its surface via the Pechini sol–gel process, resulting in the formation of the MSNs@CaTiO3:Pr3+ composite material. This material, which combines the mesoporous structure of MSNs and the red long-lasting phosphorescence property of CaTiO3:Pr3+, can be used as a novel functional drug delivery system. The results indicate that a CaTiO3:Pr3+ layer can be synthesized when the annealing temperature reaches 600°C and impurity phases start to appear when the annealing temperature reaches 800°C or higher. The specific surface area of MSNs@CaTiO3:Pr3+ decreases along with the increase of annealing temperature. The MSNs@CaTiO3:Pr3+ sample synthesized at 700°C has appropriate phosphorescence intensity and enough specific surface area (306m2/g) to load drug molecules. The as-synthesized MSNs@CaTiO3:Pr3+ composite material can be tracked in vivo by optical imaging in 12min after peritoneal injection. The quercetin-loaded MSNs@CaTiO3:Pr3+ system still shows the red phosphorescence of Pr3+ (614nm) after UV irradiation and possesses sustained drug release property. In addition, the phosphorescence intensity of Pr3+ increases with an increase in the cumulative released amount of quercetin in the system, making the extent of drug release easily identifiable, trackable, and monitorable by the change of phosphorescence. Our research supplies a new way to fabricate in vivo visible drug delivery system.

Sol–gel preparation and structural characterization of Ba2TiSi2O8 powder

Fresnoite (Ba2TiSi2O8, BTS) nano-particles were successfully synthesized at a low temperature of 900 °C by a modified Pechini sol–gel process with starting materials of Ba(NO3)2, Si(OC2H5)4 and Ti(OC3H7)4. The structural characterization of the precursors and derived synthesized oxide powders is done by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TG-DTG) and electron microscopy (SEM, EDX and TEM) studies. The effect of heat-treating temperature on the crystallinity of the fresnoite was investigated. Combined the XRD data and the strong FTIR peaks assigned to Ti–O and Si–O vibration, indicate the formation of fresnoite phase at a temperature of 900 °C. Also the nano-crystals size distribution was studied and the main diameter of nanoparticles was about 47 nm.

구형 SiO2@Y2O3: Eu 코어-쉘 복합체 형광체 합성 및 특성

The monodisperse spherical SiO 2 particles were overcoated with Y 2 O 3 : Eu 3+ phosphor layers via a Pechini sol-gel process and the resulting SiO 2 @Y 2 O 3 : Eu 3+ core-shell phosphors were subsequently annealed at 800℃ at an ambient atmosphere. The crystallographic structure, morphology, and luminescent property of core-shell structured SiO 2 @Y 2 O 3 :Eu 3+ phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL). The spherical, non-agglomerated SiO 2 particles prepared by a Stober method exhibited a relatively narrow size distribution in the range of 260-300 nm. The thickness of phosphor shell layer in the core-shell particles can be facilely controlled by varying the coating number of Y 2 O 3 : Eu 3+ phosphors. The core-shell structured SiO 2 @Y 2 O 3 : Eu 3+ phosphors showed a strong red emission, which was dominated by the 5 D 0 - 7 F 2 transition (610 nm) of Eu 3+ ion under the ultraviolet excitation (263 nm). The PL emission properties of SiO 2 @Y 2 O 3 : Eu 3+ phosphors were also compared with pure Y 2 O 3 : Eu 3+ nanophosphors.

Yellow-emitting NaCaPO_4:Mn^2+ phosphor for field emission displays

Yellow-emitting NaCaPO(4):Mn(2+) phosphors were prepared by the Pechini sol-gel process. Under low voltage electron beam excitation, the NaCaPO(4):Mn(2+) phosphor screen shows bright yellow emission (centering at 560 nm due to the (4)T(1)→(6)A(1) transition of Mn(2+)) with the CIE color coordinate (0.428, 0.552), which has a higher color purity than commercial yellow-emitting FED phosphor (Zn, CdS):Ag(+). The color range and chromaticity saturation may be greatly enhanced when the yellow-emitting NaCaPO(4):Mn(2+) is added as an additional phosphor of the typical tricolor FEDs phosphors, which make them have potential to improve the display quality of full-color FEDs.

Preparation and characterization of La0.6Sr0.4Co0.2Fe0.8O3-δ thin-film membrane on porous support by dip-coating method

Perovskite-type La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF6428) thin-film membrane prepared by modified Pechini sol–gel process, was successfully deposited on porous support of similar composition using dip-coating method. Fine grain and crack-free film with perovskite structure was obtained at sintering temperature of 800 °C and dwelling time of 60 min. The cross-sectional image indicated that LSCF6428 thin-film membrane coated on the porous support showed excellent adhesion to the support with uniform thickness. The minimum dense layer thickness obtained by dip-coating method was around 0.5 μm. It was found that the oxygen permeability of the supported thin film was lower than that of the perovskite support, which indicated that the pores of the support were reduced by thin-film deposition on the support surface. The reduction in the pore size led to the more selective permeation mechanism contributes to the overall permeation. Successful deposition of LSCF6428 thin-film membrane on porous support can be considered as a promising technique for the preparation of oxygen separation membrane.

Preparation and characterization of novel yellow pigments: hollow TiO2 spheres doped with cerium

Ce-doped TiO2 hollow yellow pigment particles were synthesized by coupling template-directed method with Pechini sol–gel process. The effects of water content, ethanol/acetonitrile volume ratio and tetrabutyl orthotitanate concentration, on the fabrication of PS@TiO2 composite particles (the key intermediate product) were investigated and the final pigments were characterized in detail by X-ray diffraction, transmission electron microscopy, scanning electron microscope, X-ray photoelectron spectroscopy, and UV–vis diffuse reflection. The results show that the optimal water content and ethanol/acetonitrile volume ratio are 0.09 mol dm−3 and 3:1, respectively, for the construction of neat PS@TiO2 core–shell structure without secondary titania particles, and that the damage of hollow spheres can be avoided by increasing the shell thickness, and that the prepared hollow spheres were well-crystallised with anatase phase TiO2 and cubic CeO2. Owing to the intrinsic yellow color and lower density, the as-prepared hollow pigments can be expected to be used for color electronic paper display.

Red-emitting Ln 2− xEu xTe 2O 6:RE (Ln = La, Y; RE = Sm 3+, Gd 3+) phosphors prepared by the Pechini sol–gel method

La 1.90Eu 0.10TeO 6:RE 3+ (RE = Gd, Sm) and Y 2TeO 6:Eu 3+nanophosphors were prepared by the Pechini sol–gel process, using lanthanide sesquioxides and telluric acid as precursors. X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence spectra (PL) and fluorescence lifetime were used to characterize the resulting phosphors. The results of XRD indicate that all samples crystallized completely at 1073 K and are isostructural with orthorhombic Ln 2TeO 6. The SEM study reveals that the samples have a strong tendency to form agglomerates with an average size ranging from 40 to 65 nm. The luminescence decay curves suggest for all samples a monoexponential behavior. The photoluminescence intensity and chromaticity were improved for excitation at 395 nm when the co-doping concentration reaches the 1% mol. The optimized phosphorsLa 1.88Eu 0.10Gd 0.02TeO 6and La 1.88Eu 0.10Sm 0.02TeO 6, could be considered an efficient red-emitting phosphor for solid-state lighting devices based on InGaN LEDs.

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.

Preparation of luminescent inorganic core/shell-structured nanoparticles

ABSTRACTSiO2 nanoparticles (NPs) were coated with Eu3+-doped calcium phosphate (CP) and Mn2+-doped ZnO to give Zn2SiO4 via a modified Pechini sol-gel process. Annealing at high temperatures resulted in NPs with an amorphous core and a crystalline luminescent shell. It was shown that this procedure can be applied to silica cores with diameters below 300 nm. By transmission electron microscopy, elemental analysis and from X-ray diffraction patterns it was determined that shell composition and structure are influenced by the annealing temperature and pH of the coating solution. Measurements of photoluminescence intensities displayed their dependency on the concentration of dopant in the resulting core/shell NPs.

Sol-Gel Synthesis of Nanocrystalline Yb3 + ∕ Ho3 + -Doped Lu2O3 as an Efficient Green Phosphor

phosphors were prepared by a Pechini sol-gel process. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL), cathodoluminescence (CL) spectra, as well as lifetimes were utilized to characterize the synthesized phosphors. XRD and HRTEM results reveal that the samples are obtained with high crystallinity. The FESEM images indicate that phosphors are composed of fine and spherical grains around in size. Under the excitation of UV light, laser, and low-voltage electron beams, all phosphors show the characteristic emission of the ion (, transition) with green luminescence, which is easily observed by our naked eyes. The corresponding luminescent mechanisms have been discussed. Due to the excellent PL (including upconversion and downconversion) properties, CL properties, and cheap materials of the phosphors, the as-prepared phosphors are potentially applied for fluorescent lamps, upconversion fluorescent labels, and field emission display devices.

Sol–gel preparation and characterization of uniform core-shell structured LaInO 3:Sm 3+/Tb 3+@SiO 2 phosphors

The core-shell structured LaInO 3:Ln 3+@SiO 2 (Ln 3+ = Sm 3+, Tb 3+) phosphors were realized by coating LaInO 3:Ln 3+ phosphors on the surface of silica microspheres via a modified Pechini sol–gel process. The phase, structure, morphology, and fluorescent properties of the materials were well characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform IR spectroscopy (FT-IR), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, and the kinetic decays, respectively. The results reveal that the obtained core-shell structured phosphors consist of amorphous silica core and crystalline LaInO 3:Ln 3+ shell, which keep the uniform spherical morphology of pure silica spheres with narrow size distribution. Upon excitation by ultraviolet (UV) irradiation or electron beam, the phosphors show the characteristic emission lines of Sm 3+ ( 4G 5/2– 6H 5/2,7/2,9/2, orange) in LaInO 3:Sm 3+@SiO 2 and characteristic emissions of Tb 3+ ( 5D 4– 7F 6,5,4,3, green) in LaInO 3:Tb 3+@SiO 2, respectively. This kind of phosphors may have potential applications in field emission displays (FEDs) based on their uniform shape, low-cost synthetic route, and diverse luminescent properties.

Spherical Zn 2SiO 4:Eu 3+@SiO 2 phosphor particles in core–shell structure: Synthesis and characterization

Spherical SiO 2 particles have been coated with Zn 2SiO 4:Eu 3+ phosphor layers by a Pechini sol–gel process. The microstructure and luminescent properties of the obtained Zn 2SiO 4:Eu 3+@SiO 2 particles were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and lifetime. The results demonstrate that the Zn 2SiO 4:Eu 3+@SiO 2 particles, which have regular and uniform spherical morphology, emitted an intensive red light emission at 613 nm under excitation at 395 nm. Besides, the effects of the Eu 3+ concentration, annealing temperature and charge compensators of Li + ions on the PL emission intensities were investigated in detail.

Photoluminescence properties of nanocrystalline La 2TeO 6:Eu 3+ phosphor prepared by Pechini sol–gel method

La 2TeO 6:Eu 3+ nanophosphors were prepared by Pechini sol–gel process, using lanthanide nitrates and telluric acid as precursor. X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TG), photoluminescence spectra (PL) and fluorescence lifetime were used to characterize the resulting phosphors. The results of XRD indicate that all samples crystallized completely at 1023 K and are isostructural with the orthorhombic La 2TeO 6. SEM study reveals that the samples have a strong tendency to form agglomerates with an average size ranging from 50 to 80 nm. The photoluminescence intensity and chromaticity were improved for excitation at 254 and 395 nm. The optimized phosphor La 1.80Eu 0.10TeO 6 could be considered as an efficient red-emitting phosphor for solid-state lighting devices based on GaN LEDs.

ChemInform Abstract: The Family of Ln2TeO6 Compounds (Ln: Y, La, Sm and Gd): Characterization and Synthesis by the Pechini Sol—Gel Process.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and characterization of monodisperse spherical SiO 2@ RE2O 3 ( RE=rare earth elements) and SiO 2@Gd 2O 3: Ln3+ ( Ln=Eu, Tb, Dy, Sm, Er, Ho) particles with core-shell structure

Spherical SiO 2 particles have been coated with rare earth oxide layers by a Pechini sol–gel process, leading to the formation of core-shell structured SiO 2@ RE 2O 3 ( RE=rare earth elements) and SiO 2@Gd 2O 3: Ln 3+ ( Ln=Eu, Tb, Dy, Sm, Er, Ho) particles. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), photoluminescence (PL), and cathodoluminescence spectra as well as lifetimes were used to characterize the resulting SiO 2@ RE 2O 3 ( RE=rare earth elements) and SiO 2@Gd 2O 3: Ln 3+ (Eu 3+, Tb 3+, Dy 3+, Sm 3+, Er 3+, Ho 3+) samples. The obtained core-shell phosphors have perfect spherical shape with narrow size distribution (average size ca. 380 nm), smooth surface and non-agglomeration. The thickness of shells could be easily controlled by changing the number of deposition cycles (40 nm for two deposition cycles). Under the excitation of ultraviolet, the Ln 3+ ion mainly shows its characteristic emissions in the core-shell particles from Gd 2O 3: Ln 3+ (Eu 3+, Tb 3+, Sm 3+, Dy 3+, Er 3+, Ho 3+) shells.