Photoluminescence properties of lamellar aggregates of titania nanosheets accommodating rare earth ions

Xin, Hao; Ma, Renzhi; Wang, Luyao; Ebina, Yasuo; Takada, Kazunori; Sasaki, Takayoshi

doi:10.1063/1.1812811

Cited by 68 publications

(67 citation statements)

References 16 publications

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“…Thus, electrons and holes produced by the band gap excitation migrate in the host layer and easily move into the interlayer to be trapped by the Eu 3+ cations. The conduction band level of TiO 2-δ nanosheet is lower than that of Nb 6 O 17 nanosheets [24], and higher than the light-emitting level of Eu 3+ [22,23].Thus, the lightemitting level of Eu 3+ is closer to the conduction band level of TiO 2-δ nanosheet than that of Nb 6 O 17 nanosheets. The weak emission intensity of Eu/NbO is presumably due to the large energy gap between conduction band level and light-emitting level of Eu 3+ .…”

Section: Resultsmentioning

confidence: 86%

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Synthesis and photoluminescence properties of layered oxides intercalated with Eu³⁺ions by electrostatic self-assembly method using oxide nanosheets

Ida

Ogata

Matsumoto

2009

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. Layered oxides intercalated with Eu3+ ions were prepared by self-assembly deposition method based on the electrostatic interaction between negative charged oxide nanosheets and Eu 3+ ions. The layered oxides were composed of two-dimensional host nanosheet layer with guest Eu 3+ ions and gave Eu 3+ emission based on an energy transfer from bandgap excitation of the host oxide nanosheets to the Eu 3+ ions. The photoluminescence properties of the Eu 3+ ions were influenced by the type of nanosheet and the intercalated water molecules. Relatively-strong emission of Eu 3+ was observed from Eu 3+ -intercalated titanate layered oxide. The intensity of Eu 3+ emission increased with increasing the amount of intercalated water molecules. This indicates that the energy transfer from TiO 2-δ nanosheet to Eu 3+ is promoted by the intercalated water molecules. In addition, the intensity of Eu 3+ emission was stronger at high pH than at low pH. This emission change is presumably due to two phenomena. One is a fine hydration state change of Eu 3+ in the interlayer, and the other is a change in energy transfer from the TiO 2-δ nanosheet to Eu 3+ . IntroductionLayered oxides composed of two-dimensional host oxide layers with guest cations have various interesting properties such as superconducting [1], ferroelectric [2] and photocatalytic properties [3]. These properties strongly depend on the combination between the host layers and the guest cations. Therefore, controlling the combination of layer structure is an important technique for material developing. Generally, two main soft-solution processes are utilized for the preparation of layered structure with desired guest cation into the interlayer. One is the ion-exchange technique carried out in an aqueous solution of a cation of interest, which is substituted for an alkaline cation of the starting layered oxide [4][5][6][7]. The other one is the direct assembly of a host oxide nanosheet and a cation of interest in a solution due to the electrostatic interaction. The latter technique is superior to the former in terms of easy and optimal intercalation of the guest cation. In the latter technique, two methods such as the electrostatic self-assembly deposition (ESD) [8] and layer-by-layer assembly (LBL) techniques [9][10][11] are available to prepare the desired layered oxides. Various kinds of intercalated layered oxides can be easily prepared under controlled pH in a solution by the ESD method, while the LBL method allows us to control the number of layers deposited on a substrate. Nanosheets can be prepared by exfoliation of layered compounds [12][13][14][15][16][17][18]. For instance, TiO 2-δ -type nanosheets [12], perovskite-type nanosheets [13][14][15] and hydroxide-type nanosheets [16,17] have been reported. The layered compounds prepared by ESD and LBL techniques have been studied in

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Section: Resultsmentioning

confidence: 86%

“…This behavior suggests that lanthanide cations in the interlayer of the TiO 2-δ -type nanosheets might result in strong emission under the excitation of TiO 2-δ -type nanosheets. Actually, several reports on luminescence properties of the nanosheet-based layered oxides have been reported [22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and photoluminescence properties of layered oxides intercalated with Eu³⁺ions by electrostatic self-assembly method using oxide nanosheets

Ida

Ogata

Matsumoto

2009

IOP Conf. Ser.: Mater. Sci. Eng.

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“…Hence the emission bands are highly dependent on the composition of the surrounding media. 35,52 Hence this band is attributed to the defect level transition associated with trapped cation, where we can see that the spectral location is not dependent on the morphology. A broad emission band at $533 nm appeared primarily due to the recombination of defects such as oxygen vacancies or surface states.…”

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confidence: 90%

Reduced recombination and enhanced UV-assisted photocatalysis by highly anisotropic titanates from electrospun TiO2–SiO2 nanostructures

2014

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The surface areas of electrospun fibers/rice grain-shaped nanostructures of TiO 2 -SiO 2 composites were further enhanced after transforming them into thorn or sponge shaped titanates via selective leaching of SiO 2 , which was reported by our group previously [RSC Adv., 2012, 2, 992]. In this study, we report on their application in photocatalytic activity (PCA) when juxtaposed with photoluminescence (PL). Two defect related bands are observed in PL and their origin is discussed in relation to calcination, crystallization and nucleation effects. The relative PL intensity for sponge shapes was the lowest and hence had the lowest radiative recombination, which suggests carrier trapping at defect centers. This enables the charge carriers to migrate to the surface and participate in the PCA. The results of PCA suggested that the sponge-shaped titanate exhibits the highest degradation rate among all samples. A plausible mechanism for the differences in PCA is proposed based on the variation in the defect-densities.

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“…In recent years, the novel luminescent properties of nanosheets and related materials have attracted great interest [1][2][3][4][5][6][7][8][9]. The thickness of a nanosheet is about 1 nm, and the lateral size ranges from several hundred square nanometers to several square micrometers, which make it possible to develop new luminescent materials by building up various functional nanosheets together with the intercalated guest ions [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Photoluminescence of nanosheets doped with rare earth ions

Zhang

Jiang

et al. 2010

Journal of Alloys and Compounds

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Photoluminescence properties of lamellar aggregates of titania nanosheets accommodating rare earth ions

Cited by 68 publications

References 16 publications

Synthesis and photoluminescence properties of layered oxides intercalated with Eu³⁺ions by electrostatic self-assembly method using oxide nanosheets

Synthesis and photoluminescence properties of layered oxides intercalated with Eu³⁺ions by electrostatic self-assembly method using oxide nanosheets

Reduced recombination and enhanced UV-assisted photocatalysis by highly anisotropic titanates from electrospun TiO2–SiO2 nanostructures

Photoluminescence of nanosheets doped with rare earth ions

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Photoluminescence properties of lamellar aggregates of titania nanosheets accommodating rare earth ions

Cited by 68 publications

References 16 publications

Synthesis and photoluminescence properties of layered oxides intercalated with Eu3+ions by electrostatic self-assembly method using oxide nanosheets

Synthesis and photoluminescence properties of layered oxides intercalated with Eu3+ions by electrostatic self-assembly method using oxide nanosheets

Reduced recombination and enhanced UV-assisted photocatalysis by highly anisotropic titanates from electrospun TiO2–SiO2 nanostructures

Photoluminescence of nanosheets doped with rare earth ions

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Synthesis and photoluminescence properties of layered oxides intercalated with Eu³⁺ions by electrostatic self-assembly method using oxide nanosheets

Synthesis and photoluminescence properties of layered oxides intercalated with Eu³⁺ions by electrostatic self-assembly method using oxide nanosheets