Different Concentrations Of Ce Research Articles

Luminescent Properties of Borosilicate Glass Doped with Cerium

ABS–BGP glasses (Al2O3–B2O3–SiO2–BaCO3–Gd2O3–P2O5) doped with different concentrations of Ce3+ ions are synthesized by the high-temperature melting technique. Optical, structural, and luminescence properties were studied. Emission connected with the transitions of Ce3+ ions is recorded in a spectral region of 350–550 nm. The luminescence decay kinetics is characterized by two components: fast and slow. The fast decay component is 45–90 ns; decreasing decay time of the slow component from 4 to 0.9 μs is observed with increasing cerium ion concentration. Based on the obtained results, it is assumed that Ce3+ ions exist in different emission states in the borosilicate glass.

Ultraviolet to visible down conversion of SiO2–Ce3+, Tb3+ nanospheres-poly-EVA films for solar cell application

Despite the many advantages which the conventional crystalline silicon solar cells (c-Si) have over other forms of renewable energy sources, they still have major drawbacks (energy loss) limiting their performance. One of the main reasons for energy loss is the ineffective utilization of short wavelength photons, especially within the UV region. The efficiency of the c-Si solar cell device can be improved by depositing the phosphor nanoparticle on top of the devise to capture and covert the UV photons from sunlight to visible or near infraded photons by a downcoversion process. Therefore, we have prepared and investigated luminescent and optical properties of downconverting nanophosphors composed of SiO2 co-doped with Ce and Tb. The dominant photoluminescence emission peak was observed at 544 nm and it was attributed to the 5D4→7F5 transition of Tb3+. The phosphors synthesized were incorporated into poly poly-ethylene vinyl acetate (poly-EVA) films which were later overlaid on a commercial silicon solar cell to and its photocurrent efficiency were measured. The phosphor films recorded a significantly good transmittance (≥76%) and also displayed a UV absorption capacity compared to that of the plain poly-EVA film. Some of the films made from different concentrations of Ce and Tb, recorded an increase in the photocurrent efficiency when deposited on the solar cell, while other compositions recorded marginal decreases compared to that of the plain EVA film.

Temperature-dependent infrared emissivity property of Ce-doped ZnO nanoparticles

The low infrared emissivity materials with good high-temperature properties remain a challenge for the infrared stealth of hot targets in 3–5 μm waveband. To further decrease the infrared emissivity of ZnO, the Ce-doped ZnO nanoparticles were prepared by a facile sol-gel method and the infrared emissivity properties in 3~5 μm waveband in high temperature conditions were deeply investigated by doping different concentration of Ce in ZnO. The influences of Ce dopant concentration on the microstructure, morphology, conductivity, lattice vibration and high-temperature infrared emissivity properties of Ce-doped ZnO were systematically studied, as well as the detailed analysis of temperature-dependent infrared emissivity properties through the conductivity and lattice vibration based on the theory of solid state physics. When the Ce dopant concentration is 3%, the infrared emissivity of Ce-doped ZnO decreases dramatically from room temperature to 800 °C in comparison with undoped ZnO and reaches the lowest value of 0.329 at 500 °C. It is indicated that the excess doping of Ce would produce an impurity phase of CeO2 in the crystal, therefore decreases the conductivity, and causes extra lattice vibration in infrared region, and results in the increase of infrared emissivity. The infrared emissivity versus temperature exhibits a “U” type curve, which is caused by the competition effects of the conductivity and lattice vibration at elevated temperature.

Control Valence and Luminescence Properties of Cerium Ions in Al2O3-SiO2 Glasses Prepared by Sol–Gel Method

In this study, the synthesis and luminescence properties (LP) of Al2O3-SiO2 glasses doped with different concentrations of Ce3+, namely, 0.05 mol.%, 0.1 mol.%, and 0.3 mol.% Ce3+, were investigated. The LP of the obtained samples were characterized by ultraviolet–visible absorption (UV–VIS) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and photoluminescence (PL) spectroscopy. The results showed that the valence states of the cerium ions can be controlled by heating the synthesized glasses in hydrogen atmosphere leading to change their LP. The existence of the absorption band at about 295 nm and of a broad band spectrum with a maximum at 250 nm can be attributed to Ce3+ ion and the charge transfer band of Ce4+ ion, respectively. A broad emission at 366 nm observed under excitation of UV light at 310 nm originated from the well-known 4f–5d transition of Ce3+ ion. The role of Al3+ ions is also considered when glass samples were treated under the hydrogen atmosphere. It is revealed that the presence of aluminum ions enabled controlling the valence states of cerium via the formation of OH bonds that can reduce Ce4+ to Ce3+ ions in glass sample treated in reduced atmosphere. The increasing of PL peaks appeared during the treatment under hydrogen atmosphere at high temperature.

Enhanced 2.0 μm emission and lowered up-conversion emission in Ce3+/Yb3+/Ho3+ tri-doped Na5Y9F32 single crystals

In this paper, the Na5Y9F32 single crystals tri-doped with ~3 mol% Yb3+/~1 mol% Ho3+, and different concentrations of Ce3+ (0, 0.2, 0.25, 0.35 and 0.4 mol%) were successfully grown by the modified Bridgman method. The absorption spectra, fluorescence spectra and decay curves of co-doped Yb3+/Ho3+ Na5Y9F32 single crystals with different concentrations of Ce3+ ions were measured. The intensity parameters of Ho3+ ions were calculated according to Judd–Ofelt theory and measured absorption spectra. The emission spectra showed the up-conversion (UC) emission intensity at 545, 657, and 755 nm reduced significantly as the addition of Ce3+. When the concentration of Ce3+ reached about 0.25 mol%, the maximum fluorescence intensity of ~2.0 μm was obtained, and the emission cross section reached 2.29 × 10−20 cm2. The mechanism of up-conversion reduction and ~2.0 μm emission enhancement in Ce3+/Yb3+/Ho3+ tri-doped Na5Y9F32 crystals was discussed from their energy level diagrams and optical spectra. The cross-relaxation (CR) energy transfer efficiency between Ho3+ and Ce3+ ions were 36.3% calculated from the measured lifetime of Yb3+ /Ho3+ co-doped and Ce3+/Yb3+/Ho3+ tri-doped samples. Analysis on the fluorescence dynamics indicated that electric dipole-dipole is dominant for the energy transfer from Ho3+ to Ce3+ ions. The results show that Ce3+/Yb3+/Ho3+ tri-doped Na5Y9F32 crystals has certain application prospects in improving the performance of Ho3+ ~2.0 μm solid-state laser.

Thermo- radio- and optically stimulated luminescence of Ce-doped KYF4 single crystals

The goals of this work are to determine the luminescence properties of KYF4 single crystals doped with different concentrations of Ce3+ ions and to evaluate their possible application as a detector of beta radiation. In particular, thermoluminiscence, radioluminiscence and optically stimulated luminescence properties of KYF4: Ce3+ exposed to beta radiation have been studied and very good dosimetric properties have been obtained within the dose range 0.02–20 Gy.

Structural and optical characterization of RbLaP4O12:Ln3+ (Ln3+ = Ce3+, Nd3+, Tm3+, or Yb3+).

In this work, for the first time, detailed structural and optical characterization of RbLaP4O12 doped with different concentrations of Ce3+, Nd3+, Tm3+, or Yb3+ ions is reported. The samples were obtained via a precipitation technique. Their structural characterization was performed using X-ray diffraction (XRD), and infrared and Raman spectroscopies. Following XRD data, the unit cell parameters of host lattices were calculated using Rietveld refinement. It was found that an increase in the dopant content leads to a decrease in the unit cell volume. The optical characterization of RbLaP4O12:Ln3+ was carried out by collecting absorption and emission spectra, as well as luminescence decay profiles. Following absorption spectra, the energy band gap of the studied matrix was determined. It was found that the broad absorption band located in the ultra-violet range, in most cases ascribed to charge transfer or f-d transitions, is in fact related to the absorption of the host lattice. The analysis of luminescence properties allowed us to investigate possible ways of depopulation emission levels of impurities.

CeO2 doped Al2O3 composite ceramic coatings fabricated on γ–TiAl alloys via cathodic plasma electrolytic deposition

CeO2 doped Al2O3 composite ceramic coatings were fabricated on TiAl alloys via cathodic plasma electrolytic deposition technique in 0.3 mol/L Al(NO3)3 ethanol electrolytes containing different concentrations of Ce(NO3)4. The effects of CeO2 doping contents on microstructures, elemental compositions, mechanical properties, high temperature oxidation resistance at 850 °C, and wear resistance against GCr15 balls at 200 °C of the coatings were investigated. The results indicated that the contents of CeO2 in composite coatings increased with increasing concentration of Ce(NO3)4, and composite coatings were composed of α–Al2O3 mainly, γ–Al2O3, and a little CeO2. The doping of CeO2 helped to improve the phase inversion from γ–Al2O3 to α–Al2O3. The crystallization and wear resistance of composite coatings increased due to the doping of CeO2. In the electrolyte containing 0.015 mol/L Ce(NO3)4, the coating was the most uniform and compact, and of the best high temperature oxidation resistance and mechanical properties.

Effect of concentration of Ce(NO3)3 · 6H2O and temperature on the corrosion resistance of Al2O3/cerium oxide composite films on 1060 Al alloy

In this paper, Al2O3/cerium oxide composite films were prepared on the surface of aluminum by anodic oxidation and chemical solution deposition. The aluminum was firstly anodized in sulfuric acid, then treated with different concentrations of Ce(NO3)3 · 6H2O solution at different temperatures. X‐ray diffraction (XRD), energy dispersive spectrometer (EDS), scanning electron microscope (SEM), electrochemical impedance spectroscopy (EIS), and electrochemical polarization tests were used to characterize the properties of the composite films. The results indicate that the Al2O3/cerium oxide composite films successfully form on 1060 Al alloy, and the best condition of film‐forming is 2 g/L Ce(NO3)3 · 6H2O and 50 °C. Al2O3/cerium oxide composite film under this condition has a uniform, smooth, and pyknotic surface topography and optimal corrosion resistance. The corrosion density at that time is 1.106 × 10−6 A/cm2 and the corrosion potential is −0.458 V.

Ca20Al26Mg3Si3O68:Ce3+,Tb3+ Phosphors: Preferential Site Occupation, Color-Tunable Luminescence and Device Application

A novel luminescence material of emitting color-tunable Ca20Al26Mg3Si3O68 (denoted as CAMSO):Ce3+,Tb3+ phosphors have been synthesized via the high temperature solid-phase reaction process. The crystal cell structure, photoluminescence properties and application performance such as thermal stability and LED device performance of the phosphors were researched in detail. CAMSO:Ce3+,Tb3+ phosphors showed multicolor with the different concentration of Ce3+ and Tb3+ ions. Although the concentration of Ce3+ ions was settled and there was the existence of energy transfer from Ce3+ to Tb3+ ions, it was found that Ce3+ ions’ blue light emission intensity showed abnormal increasing with the increase of Tb3+ ions doping concentration. The irregular phenomenon was discussed in detail. The phosphor CAMSO:0.2Ce3+,0.1Tb3+ photoluminescence emission intensity motivated by 374 nm at 150 °C retained about 81% of that measured at room temperature, which demonstrating the good thermal and color stability of the sample. In ad...

X-ray Induced Luminescence and Physical Properties of Lithium Lanthanum Borate Glass Doped with Ce3+ for Radiation Detection Material

Abstract Lithium lanthanum borate glasses doped with different concentration of Ce3+ were synthesized to study the luminescence and physical properties. Glass density was measured by Archimedes’ principle and taken to evaluate the molar volume. Density and molar volume value increases with increasing of Ce3+ concentration. Glass network of borate former, tetrahedral BO4 and trigonal BO3, was proved by Fourier transform infrared spectroscopy. From absorption spectra, these glasses can absorb the ultraviolet radiation. The luminescence spectra under x-ray induction show that glasses emit the photons in the range of 360 – 530 nm wavelength. These emissions correspond to the 5d - 2F5/2 and 5d - 2F7/2 transitions of Ce3+. The luminescence decay curves were observed and fitted the fast life time values in the order of ten nanoseconds. This Ce3+ doped glass performs the interesting properties which can be developed for using as a scintillator in x-ray detection device.

Scintillation properties of Ce-doped Yb3Al5O12 single crystals

Yb3Al5O12 (YbAG) single crystals were prepared by the Floating Zone (FZ) method with and without doping with different concentrations of Ce, and then we evaluated their basic scintillation properties. All the samples showed scintillation with emission peaks in the range from 300 nm to 600 nm. The origin of this emission peak was attributed to the charge transfer luminescence of Yb3+. In addition, the Ce-doped samples showed three strong emission bands, in which the emission origin is also predominantly due to the charge transfer emission but the spectrum was deformed due to a self-absorption by the 4f-5d transitions of Ce3+. Scintillation decay profiles of all the samples were approximated by a sum of two exponential decay functions, and the obtained decay times were 1 and 9–10 ns. Among the present samples, the 0.5% Ce-doped sample showed the lowest scintillation afterglow level. All the samples demonstrated a full energy peak in the pulse height spectrum measured under 241Am 5.5 MeV α-ray irradiation. Among the present samples, the undoped sample showed the highest light yield with a value of 20 ph/5.5 MeV-α.

Dosimetric, optical and radio-luminescence properties of Ce-doped 90KPO3-10Al2O3 glasses

In this study, we evaluated the dosimetric and Radio-luminescence (RL) properties of Ce-doped 90KPO3-10Al2O3 glasses. The glass samples doped with different concentrations of Ce (0.05, 0.1, 0.5 and 1.0 mol%) were synthesized by the melt quenching method. The Ce-doped samples had high transmittance (80–90%) at wavelengths longer than 350 nm. From the measurements of photoluminescence (PL) decay curve, the luminescence decay time was confirmed to be typical for the 5d-4f transition of Ce3+ (30 ns). A similar decay time as that of PL was also confirmed in RL; therefore, the dominant emission origin of RL was ascribed to Ce3+. In addition, the samples showed thermally-stimulated luminescence, and the sensitivity of integrated signal over the glow curve was confirmed to range from 0.01 mGy to 1 Gy for the 0.5% Ce-doped sample which showed the highest sensitivity among the present materials.

Steady state and time–resolved luminescence of Tb3+/Ce3+ doped ABS-BGP glasses

ABS-BGP (Al2O3-B2O3-SiO2-BaCO3-Gd2O3-P2O5) glasses doped with different concentrations of Ce3+ and Tb3+ were prepared by high temperature melting method. The luminescent properties using steady state and time-resolved luminescence were investigated. The time-resolved luminescence was studied by pulse photo- and cathodoluminescence type of excitation. The strong “blue” emission due to radiation transition of Ce3+ ions under selective excitation in nanosecond time range was recorded. The decay time of Tb3+ ions under the electron beam excitation at 542 nm is 2.2 ms. It was demonstrated that the luminescence efficiency does not depend on the Ce3+ concentration excited by the LED chip. The decay kinetics are characterized by a single exponential function with the decay time τ = 30 ns under photoexcitation. However there are two components of luminescence decay τ1 = 35 ns, τ2 = 540 ns when excited by a flow of electrons. The difference in luminescence decay kinetics under various type of excitation was discussed. The results indicate that ABS-BGP glasses would be excellent candidate for visible luminescent device applications.

Effects of Cerium Concentration and Solvent on Physical and Chemical Characterization of Rapid Setting Cement

This study was conducted to explore the feasibility of rapid setting cement (RSC) as an agent of immobilization for certain elements such as fission products or radioactive materials through evaluation of the setting time, apparent porosity, bulk density, pH value, conductivity, compressive strength, and compositions. Two different cylindrical sample groups were created. The first group was a mixture of the cement powder with deionized water (DIW) and different concentrations of Ce (0, 2, 5, 7.5, and 10 wt%). The second group included the cement powder, artificial seawater (ASW), and same Ce concentration patterns. Samples were analyzed by X-ray diffraction (XRD), fluorescence analysis (XRF), and scanning electron microscopy including energy-dispersive X-ray spectroscopy. The results showed that the final setting time and compressive strength of RSC with both solutions (DIW and ASW) decreased as Ce content increased while opposite trends were observed for the apparent porosity and bulk density of RSC under the same concentration effect. As salt contents increased, the pH decreased while the conductivity increased gradually. The XRD patterns revealed that two newly identified phases were reported, namely CeAl11O18 and Ce4.667 (SiO4)3O. The XRF results showed uniform distribution of Ce concentrations within RSC with both solutions (DIW and ASW). The morphology of matrix samples showed that the existence of Ce distributed on the pore wall or clustered with Si, Al, Mg, K, P, Fe, and O.

EPR study of ceria nanoparticles containing different concentration of Ce3+ ions

The electron paramagnetic resonance of Ce3+ ions in ceria is a rather controversial issue. In this report we analyze the EPR line with g ∼1.97 in the absorption spectra of ceria powders, which has been assigned in many studies to Ce3+ ions. Such an assignment is not in agreement with the experimental data nor with the theory of spin-lattice relaxation of rare earth ions in solids. Our statement is supported by our experimental results based on EPR spectroscopy of nanocrystalline ceria, synthesized in various ways, as well as by magnetization measurements of as-prepared and vacuum-annealed ceria nanoparticles. The possible model of the paramagnetic center, which is assigned to the EPR line with g ∼1.97 in ceria, is an electron trapped near the surface Ce3+/Ce4+ redox pair.

Photoluminescence and scintillation properties of Ce-doped Sr2Al2SiO7 crystals

Undoped and Ce-doped Sr2Al2SiO7 bulk crystals with different concentrations of Ce were synthesized by the floating zone method. Under X-ray irradiation, the both undoped and Ce-doped samples show scintillation with broad emission with decay time constants of approximately 30 and 300 ns. By utilizing photoluminescence (PL) techniques, we attributed the origin of the former emission component is due to the 5d-4f transitions of Ce3+ while the one of the latter emission is due the host. The scintillation afterglow levels depends on the concentration of Ce and are on an order of ppm. From the pulse height spectrum measured under 241Am 59.5 keV γ-ray irradiation, the 0.3% Ce-doped Sr2Al2SiO7 crystal was revealed to show the absolute scintillation light yield of 1100 ph/MeV, which is the highest among the present samples. In addition, the Ce-doped samples show TL properties with a glow peak at 250 °C and a shoulder around 130 °C.

Scintillation and dosimetric properties of Ce-doped 6LiF-CaF2 eutectic composites

Scintillation and dosimetric properties of 6LiF-CaF2 eutectic composites doped with different concentrations of Ce (0, 0.1 and 0.5%) were investigated. The Ce-doped samples showed scintillation due to the 5 d-4f transitions of Ce3+ and self-trapped excitons (STE) at 320–340 and 300 nm, respectively. Furthermore, the Ce-doped samples exhibited thermally-stimulated luminescence (TSL) with glow peaks around 150 °C after X-ray irradiation of 1000 mGy. The TSL response of the 0.5% Ce-doped sample increased monotonically with X-ray dose over a dose range of 0.1–1000 mGy. Moreover, the Ce-doped samples showed optically-stimulated luminescence (OSL) with peaks at 320–340 nm due to the 5 d-4f transitions of Ce3+ under 630 nm stimulation light after X-ray irradiation of 1000 mGy.

Characterization of Ce-doped lithium borosilicate glasses as tissue-equivalent phosphors for radiation measurements

We synthesized lithium borosilicate glasses doped with different concentrations of Ce (0.01%, 0.03%, 0.10%, and 0.30%) as well as undoped glass, and then the prepared glasses were studied for their optical, dosimetric, and scintillation properties. The Ce-doped samples exhibited scintillation and photoluminescence (PL) due to the 5d–4f transitions of Ce3+, with broad spectral features peaking around 350 nm. The PL and scintillation decay times were 30.7–31.6 ns and 64–82 ns, respectively. As the concentration of Ce increased, the scintillation intensity increased. Among the present samples, the 0.03% Ce-doped sample showed the highest PL quantum yield (9.7%). The quantum yield was well correlated with the decay time. In addition, thermally stimulated luminescence was observed after irradiation with X-rays. The sensitivity was highest for the 0.10% Ce-doped sample, having a dynamic range from 0.05 mGy to 10 Gy, which was equivalent to that of commercial dosimeters. Furthermore, the thermally stimulated luminescence spectrum was due to the 5d–4f transitions of Ce3+. The concentration of Ce that gave the highest sensitivity was 0.10%.

Scintillation and dosimetric properties of Ce-doped strontium aluminoborate glasses

Strontium aluminoborate glasses with different concentrations of Ce (0, 0.01, 0.05, 0.1 and 0.5mol%) were synthesized by the conventional melt-quenching technique. After the synthesis, photoluminescence (PL), scintillation and dosimetric properties of the samples were evaluated systematically. In the photoluminescence and scintillation spectra, a sharp peak around 370nm due to the 5d-4f transitions of Ce was observed. The 0.05% Ce-doped sample showed the highest intensity in PL and scintillation among the samples investigated. The 0.01–0.1% Ce-doped samples also showed thermally-stimulated luminescence (TSL) with a glow peak of around 90°C after X-ray irradiation. The TSL response of 0.01–0.05% Ce-doped samples increased monotonically with X-ray dose over a dose range of 10−1–104mGy.