Optical and photoconductive properties of cerium-doped crystalline solids

Yen, W. M.; Raukas, M.; Basun, S. A.; Schaik, Willem van; Happek, U.

doi:10.1016/s0022-2313(96)00107-x

Cited by 163 publications

(82 citation statements)

References 19 publications

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“…Among the lanthanide oxides, the catalytic properties of ceria have received much attention due to two features of (1) the redox couple Ce 3+ /Ce 4+ with the ability of ceria to shift between CeO 2 and Ce 2 O 3 under oxidizing and reducing conditions; and (2) the easy formation of labile oxygen vacancies (OV) with the relatively high mobility of bulk oxygen species [18]. Furthermore, the different electronic structures of the Ce 3+ with 4f 1 5d 0 and the Ce 4+ with 4f 0 5d 0 would lead to different optical properties [24][25] and dissimilar catalytic properties for CeO 2 and CeO x -TiO 2 and also Ce 3+ -TiO 2 [26][27].…”

Section: Introductionmentioning

confidence: 99%

Enhanced photocatalytic activity of Ce3+–TiO2 for 2-mercaptobenzothiazole degradation in aqueous suspension for odour control

Hou

et al. 2005

Applied Catalysis A: General

417

146

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Abstract:A series of cerium ion-doped titanium dioxide (Ce 3+ -TiO 2 ) catalysts with special 4f electron configuration was prepared by a sol-gel process and characterized by Brunauer-EmmettTeller method, X-ray diffraction, X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS), and also photoluminescence (PL) emission spectroscopy. The photocatalytic activity of Ce 3+ -TiO 2 catalysts was evaluated in the 2-mercaptobenzothiazole (MBT) degradation in aqueous suspension under UV or visible light illumination. The experimental results demonstrated that the overall photocatalytic activity of Ce 3+ -TiO 2 catalysts in MBT degradation was signigicantly enhanced due to higher adsorption capacity and better separation of electron-hole pairs.The experimental results verified that both the adsorption equilibrium constant (K a ) and the saturated adsorption amount ( max ) increased with the increase of cerium ion content. The results of XPS analysis showed that the Ti 3+ , Ce 3+ , and Ce 4+ ions reside in the Ce 3+ -TiO 2 catalysts. The results of DRS analysis indicated that the Ce 3+ -TiO 2 catalysts had significant optical absorption in the visible region between 400-500 nm because electrons could be excited from the valence band of TiO 2 or ground state of cerium oxides to Ce 4f level. In the meantime, the dependence of the electron-hole pair separation on cerium ion content was investigated by the PL analysis. It was found that the separation efficiency of electron-hole pairs increased with the increase of cerium ion content at first and then decreased when the cerium ion content exceeded its optimal value. It is proposed that the formation of two sub-energy levels (defect level and Ce 4f level) in Ce 3+ -TiO 2 might be a critical reason to eliminate the recombination of electron-hole pairs and to enhance the photocatalytic activity.

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Section: Introductionmentioning

confidence: 99%

Enhanced photocatalytic activity of Ce3+–TiO2 for 2-mercaptobenzothiazole degradation in aqueous suspension for odour control

Hou

et al. 2005

Applied Catalysis A: General

417

146

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“…Absence of 5d → 4f luminescence of Ce 3+ therefore strongly suggests an alternative nonradiative luminescence quenching route. Photoconductivity studies on Lu 2 4 demonstrated that luminescence quenching proceeds via Ce 3+ ionization and subsequent nonradiative recombination between Ce 4+ and the electron. The preferred nonradiative ionization route was explained by the unfavorable location of the lowest energy 5d state in the conduction band ͑CB͒ of Lu 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

Luminescence quenching by photoionization and electron transport in a LaAlO3:Ce3+ crystal

Kolk

Haas

Bos

et al. 2007

Journal of Applied Physics

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A combined photoconductivity, absorption, and thermoluminescence study was performed to understand the absence of luminescence from Ce 3+ in LaAlO 3 :Ce 3+ . It is demonstrated that the absence of luminescence is the result of Ce 3+ ionization from the 5d excited states, which are all located in the conduction band. Ce 3+ ionization is accompanied by the formation of several broad absorption and photoconductivity bands, which are assigned to electron traps. A time and temperature dependent optical investigation of these traps reveals the conditions under which electrons are transferred from Ce 3+ to traps and vice versa, from traps back to Ce 4+ . The observed difference in energy needed to thermally or optically release electrons from traps is qualitatively explained in terms of the location of the ground and excited states of the electron traps with respect to the conduction band.

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“…[25][26][27][28] Struck and Fonger proposed a quantitative method to describe the radiative and non-radiative relaxation from excited states using a quantum mechanical single configurational coordinate (QMSCC) model.…”

mentioning

confidence: 99%

“…In an attempt to investigate the relation between the compositions, structures of the host crystals, and their luminescence properties, the thermal quenching of these phosphors is analyzed. The research about the thermal quenching of phosphors have increased in these days, [19][20][21][22][23][24][25][26][27][28] and two processes of the thermal quenching are mainly considered. One is the thermally activated cross over from the excited state to the ground state; [19][20][21][22][23][24] the other is the thermal ionization from the excited state to the bottom of the conduction band (CB).…”

mentioning

confidence: 99%

“…One is the thermally activated cross over from the excited state to the ground state; [19][20][21][22][23][24] the other is the thermal ionization from the excited state to the bottom of the conduction band (CB). [25][26][27][28] Struck and Fonger proposed a quantitative method to describe the radiative and non-radiative relaxation from excited states using a quantum mechanical single configurational coordinate (QMSCC) model. 19 Parameters for this model are depicted in Fig.…”

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confidence: 99%

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Editors' Choice—Thermal Quenching Analyses of Eu²⁺-Activated Sr-Containing Sialon Phosphors Using the Thermally Activated Cross-Over Model

Fukuda¹

2017

ECS J. Solid State Sci. Technol.

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To investigate the relation between the luminescence properties and the crystal structure, the thermal quenching of three kinds of Eu 2+ -activated Sr-containing sialon phosphors are analyzed using the Struck-Fonger model. The inherent frequency of the host lattice ω is calculated from the measured internal quantum efficiency at various temperatures, and the results confirm that the inherent frequency of the host lattice ω dominates the thermal quenching of these phosphors. Moreover, clarification of the relationship between the inherent frequency of the host lattice ω and the host crystal structure reveals that the covalence and density of the host crystal structure mainly influence the inherent frequency and therefore influence the extent of the thermal quenching. 17,18 Despite being composed of the same elements and activated with the same ion, the divalent Eu ion, these three phosphors emit different color and their luminescence properties are not the same. The differences between their crystal structures and compositions are thought to result in these different luminescence properties. In an attempt to investigate the relation between the compositions, structures of the host crystals, and their luminescence properties, the thermal quenching of these phosphors is analyzed. The research about the thermal quenching of phosphors have increased in these days, [19][20][21][22][23][24][25][26][27][28] and two processes of the thermal quenching are mainly considered. One is the thermally activated cross over from the excited state to the ground state;19-24 the other is the thermal ionization from the excited state to the bottom of the conduction band (CB). [25][26][27][28] Struck and Fonger proposed a quantitative method to describe the radiative and non-radiative relaxation from excited states using a quantum mechanical single configurational coordinate (QMSCC) model.19 Parameters for this model are depicted in Fig. 1. In this figure the horizontal coordinate is the single configurational coordinate r, and the vertical coordinate is the total energy E of the system. The parabolas u and v are the potential energy wells of the electronic ground state and the relevant excited state, respectively. The u and v parabola quantum numbers, wavefunctions, and phonon energies are denoted n, u n , ω u and m, v m , ω v , respectively. r 0 measures the Franck-Condon (FC) offset and is expressed in terms of S u and S v : r 0 2 = 2(S u + S v ). S u ω u and S v ω v represent the relaxation energies after emission and excitation, respectively. The QMSCC model is taken in the thermal equilibrium and the v m → u n rate is proportional to the squared overlap integral u n |v m 2 . 29 These overlap integrals are evaluated using the recursion formulas given by Manneback,20 offering the possibility of a quantitative treatment of radiative and nonradiative processes. Struck and Fonger applied QMSCC-calculation to the luminescence properties of ruby and emerald. 21 Bleijenberg and Blasse performed QMSCC calculations on model phosphor syste...

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Optical and photoconductive properties of cerium-doped crystalline solids

Cited by 163 publications

References 19 publications

Enhanced photocatalytic activity of Ce3+–TiO2 for 2-mercaptobenzothiazole degradation in aqueous suspension for odour control

Enhanced photocatalytic activity of Ce3+–TiO2 for 2-mercaptobenzothiazole degradation in aqueous suspension for odour control

Luminescence quenching by photoionization and electron transport in a LaAlO3:Ce3+ crystal

Editors' Choice—Thermal Quenching Analyses of Eu²⁺-Activated Sr-Containing Sialon Phosphors Using the Thermally Activated Cross-Over Model

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Optical and photoconductive properties of cerium-doped crystalline solids

Cited by 163 publications

References 19 publications

Enhanced photocatalytic activity of Ce3+–TiO2 for 2-mercaptobenzothiazole degradation in aqueous suspension for odour control

Enhanced photocatalytic activity of Ce3+–TiO2 for 2-mercaptobenzothiazole degradation in aqueous suspension for odour control

Luminescence quenching by photoionization and electron transport in a LaAlO3:Ce3+ crystal

Editors' Choice—Thermal Quenching Analyses of Eu2+-Activated Sr-Containing Sialon Phosphors Using the Thermally Activated Cross-Over Model

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Product

Resources

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Editors' Choice—Thermal Quenching Analyses of Eu²⁺-Activated Sr-Containing Sialon Phosphors Using the Thermally Activated Cross-Over Model