Effects of urea concentration and reaction temperature on morphology of gadolinium compounds prepared by homogeneous precipitation

Park, In Yong; Kim, Dong-Jin; Lee, Jongwon; Lee, Sang Ho; Kim, Kyu-Jin

doi:10.1016/j.matchemphys.2007.05.050

Cited by 51 publications

(20 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These results indicate that gadolinium hinders hematite formation and favors the production of gadolinium ferrite (FeGdO 3 ), instead. The iron-free solid showed endothermic peaks at 220, 440 and 530 • C, assigned to the dehydration process of gadolinium hydroxide (Gd(OH) 3 ) to produce gadolinium oxide (Gd 2 O 3 ) [26] as well as to the decomposition of carbonate species [24]. The curves did not present thermal events at temperatures above 800 • C, indicating the stability of the phases formed.…”

Section: Resultsmentioning

confidence: 99%

“…It is observed that the presence of gadolinium in solids shifted the second, third and fourth peaks to higher temperatures, indicating that gadolinium made the decomposition of iron hydroxide more difficult, increased by gadolinium content. Pure gadolinium oxide showed weight losses attributed to decomposition of gadolinium of carbonate species occurred simultaneously with dehydration, at temperatures above 400 • C [24]. For all samples no weight loss was observed above 600 • C.…”

Section: Catalyst Evaluationmentioning

confidence: 89%

See 1 more Smart Citation

Effect of gadolinium on the catalytic properties of iron oxides for WGSR

et al. 2013

View full text Add to dashboard Cite

Due to the need for energy supply through cleaner and more efficient technologies, the interest for the water gas shift reaction (WGSR) has increased especially due to its role in purifying hydrogen-rich streams. In order to find alternative catalysts for this reaction, the effect of gadolinium and its amount on the properties of iron oxide-based catalysts was studied in this work. Samples with different gadolinium to iron molar ratio (0.05; 0.1 and 0.15) were prepared by sol-gel method and characterized by chemical analysis, thermogravimetry, differential scanning calorimetry, infrared spectroscopy, X-ray diffraction, Mössbauer spectroscopy, specific surface area measurements and thermoprogrammed reduction. The catalysts were evaluated in WGSR at 1 atm in the range of 250-400 • C. Hematite and gadolinium ferrite were detected for all fresh catalysts based on iron and gadolinium while magnetite and iron carbides and gadolinium oxide were found for the spent ones. The specific surface area increased due to gadolinium, related to its role as spacer. Gadolinium made the reduction of Fe 3+ and Fe 2+ species more difficult for all catalysts and then inhibited the production of iron carbides during reaction, increasing the activity. The catalyst with Gd/Fe = 0.10 showed the highest activity that was assigned to its highest specific surface area, which exposed more active sites. No methane or ethane was found indicating that the iron carbides were inactive to Fischer-Tropsch synthesis under reaction conditions.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Catalyst Evaluationmentioning

confidence: 89%

Effect of gadolinium on the catalytic properties of iron oxides for WGSR

et al. 2013

View full text Add to dashboard Cite

show abstract

“…Gd 2 O 3 :Eu 3+ nanophosphor was prepared using the homogeneous precipitation technique by the following procedure [9,10]. Appropriate amounts of Gd 2 O 3 and Eu 2 O 3 were dissolved in dilute HNO 3 solution.…”

Section: Preparation Of Gd 2 O 3 :Eu 3+ Nanophosphormentioning

confidence: 99%

“…In the present study, Gd 2 O 3 :Eu 3+ nanophosphor was prepared by the homogeneous precipitation method [9,10]. Since Gd 2 O 3 is isostructural with Y 2 O 3 , Gd 2 O 3 :Eu 3+ can be used as a phosphor and is comparable to Y 2 O 3 :Eu 3+ .…”

mentioning

confidence: 99%

Preparation of Gd2O3:Eu3+ downconversion luminescent material and its application in dye-sensitized solar cells

Lin

et al. 2011

Chin. Sci. Bull.

View full text Add to dashboard Cite

Gd 2 O 3 :Eu 3+ downconversion luminescent powder was prepared using the homogeneous precipitation method. Its optical properties were analyzed and it was introduced into a dye-sensitized solar cell (DSSC). As a luminescence medium, Gd 2 O 3 :Eu 3+ improved light harvesting via conversion luminescence and increased the photocurrent of the DSSC. As a p-type dopant insulating rare earth oxides form an energy barrier, and the Gd 2 O 3 :Eu 3+ elevated the energy level of the oxide film and increased the photovoltage. The photoelectric conversion efficiency for a DSSC with Gd 2 O 3 :Eu 3+ doping (6 : 100) reached 7.01%, which was 17.4% higher than the photoelectrical conversion efficiency of a DSSC without Gd 2 O 3 :Eu 3+ doping. dye-sensitized solar cell, downconversion, rare-earth oxide, luminescent material, p-type doping Citation: Li Q B, Lin J M, Wu J H, et al. Preparation of Gd 2 O 3 :Eu 3+ downconversion luminescent material and its application in dye-sensitized solar cells. Considerable effort has been devoted to the dye-sensitized solar cell (DSSC) since the first prototype was reported by O'Regan et al. [1] and Gratzel [2]. There has been great progress in development of the DSSC over the past decade, because of its low cost, simple preparation, and conversion efficiency which has reached 11% [3]. In general, the sensitizer of the DSSC contains mainly N3 and N719 dyes [1-6], and the DSSC consists of a porous nanocrystalline TiO 2 film sensitized by a dye for absorbing incident light. However, even the best of these dyes (N719) absorbs only visible light in the wavelength range 300-800 nm, while the standard air-mass (AM1.5) terrestrial spectrum covers the wavelength region from UV to IR (200-2500 nm). Downconversion materials are a viable option for reducing the spectral mismatch losses. Trupke et al. [7] have suggested that the dye molecules in a DSSC could avoid the absorption of high-energy photons in a conventional semiconductor solar cell with infinite bands, by directing the high-energy part of the solar spectrum toward a downconverter with suitable low-pass mirrors. However, few studies have been carried out on the use of conversion luminescence in the DSSC. Our group [8] has reported work in which Y 2 O 3 :Eu 3+ nanophosphor was prepared by the co-precipitation method. As a luminescence medium Y 2 O 3 :Eu 3+ improved light harvesting via a conversion luminescence process and increased the photocurrent. As a p-type dopant, Y 2 O 3 :Eu 3+ elevated the energy level of the oxide film and increased the photovoltage. In the present study, Gd 2 O 3 :Eu 3+ nanophosphor was prepared by the homogeneous precipitation method [9,10]. Since Gd 2 O 3 is isostructural with Y 2 O 3 , Gd 2 O 3 :Eu 3+ can be used as a phosphor and is comparable to Y 2 O 3 :Eu 3+ . Gd 2 O 3 :Eu 3+ has been reported to be a more effective phosphor than Y 2 O 3 :Eu 3+ for particular applications such as an X-ray scintillator, because Gd 2 O 3 has higher density and light efficiency [11]. In addition, the synthesis of Gd 2 O 3 :Eu 3+ phosp...

show abstract

“…As for phosphor powders, the crystallinity, particle size, and surface roughness have strong effects on photoluminescence [8]. For example, the phosphor prepared by a solid-state reaction method has big enough crystallite size, irregular morphology, and high hardness, which is not good for luminescence in application.…”

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of Eu3+-doped CaCO3 phosphor by microwave synthesis

Kang

Yin

et al. 2009

Rare Metals

View full text Add to dashboard Cite

A Eu 3+ -doped CaCO 3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO 3 :Eu 3+ particles are needle-like in the length range of 5.0-10.0 μm. The results of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy indicate that pure aragonite CaCO 3 :Eu 3+ is prepared using microwave irradiation and the Eu 3+ ion as a luminescence center inhabits the site of Ca 2+ . The photoluminescence excitation (PLE) spectrum shows that the strong broad band at around 270 nm and weak sharp lines in 300-550 nm are assigned to the charge transfer band of Eu 3+ −O 2− and intra-configurational 4f-4f transitions of Eu 3+ , respectively. The photoluminescence (PL) spectrum implies that the red luminescence can be attributed to the transitions from the 5 D 0 excited level to the 7 F J (J = 0, 1, 2, 3, 4) levels of Eu 3+ ions with the mainly electric dipole transition 5 D 0 → 7 F 2 (614 and 620 nm), and the Eu 3+ ions prefer to occupy the low symmetric site in the crystal lattice.

show abstract

Effects of urea concentration and reaction temperature on morphology of gadolinium compounds prepared by homogeneous precipitation

Cited by 51 publications

References 27 publications

Effect of gadolinium on the catalytic properties of iron oxides for WGSR

Effect of gadolinium on the catalytic properties of iron oxides for WGSR

Preparation of Gd2O3:Eu3+ downconversion luminescent material and its application in dye-sensitized solar cells

Preparation and characterization of Eu3+-doped CaCO3 phosphor by microwave synthesis

Contact Info

Product

Resources

About