Evidence of three different Eu2+ sites and their luminescence quenching processes in CaAl2O4:Eu2+

Ueda, Jumpei; Shinoda, Tatsuaki; Tanabe, Setsuhisa

doi:10.1016/j.optmat.2014.12.010

Cited by 19 publications

(13 citation statements)

References 38 publications

(48 reference statements)

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“…The emission spectrum of CaAl 2 O 4 :Eu 2+ (x Ca =0.97) in Fig. 7(a) is similar to the PL spectrum measured at 300 K by Ueda et al [14]. By comparing the PL spectrum of BA (x Ca =0) in Fig.…”

Section: Pl and CL Spectrasupporting

confidence: 80%

Crystal structure, photoluminescence and cathodoluminescence of Ba_1-xCa_xAl₂O₄ doped with Eu²⁺

Volhard¹,

Engelsen²,

Fern³

et al. 2019

Opt. Mater. Express

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The synthesis, crystal structure, photoluminescence (PL) and cathodoluminescence (CL) spectra of Ba 1−x Ca x Al 2 O 4 doped with 3 mol% Eu 2+ between x = 0 and x = 1 are described. The molar fractions of the alkaline earth elements were varied in steps of 0.1. The materials have been synthesized by all solid state reactions at 1300°C in mixed gas (H 2 /N 2). The identification of the crystal phases in the samples was based on analyses of the X-ray diffraction patterns. The Ba 1−x Ca x Al 2 O 4 system contains one dominant monoclinic phase, one dominant hexagonal phase and two different cubic phases that were present in low concentrations. The main characteristic of the PL spectra was that the intensity of the Eu 2+ photoluminescence decreased upon adding a second alkaline earth ion in the aluminate lattice. The hexagonal and monoclinic phases in the Ba 1−x Ca x Al 2 O 4 samples showed an unexpected behaviour, namely increasing their unit cell volumes upon decreasing the mole fraction of Ba 2+. For the hexagonal phase this behaviour has been explained qualitatively in terms of enhanced spontaneous polarization of the uncompensated anti-ferroelectric state.

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Section: Pl and CL Spectrasupporting

confidence: 80%

Crystal structure, photoluminescence and cathodoluminescence of Ba_1-xCa_xAl₂O₄ doped with Eu²⁺

Volhard¹,

Engelsen²,

Fern³

et al. 2019

Opt. Mater. Express

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“…12 Thus, they proposed the thermal ionization quenching in CaAlSiN3:Eu 2+ as well as CaAlSiN3:Yb 2+ . Also, because the thermal ionization quenching was predicted and proved in other Eu 2+ phosphors by the investigation of energy diagram [13][14][15] and photoconductivity 16,17 , the thermal ionization process may be the most probable path in the CaAlSiN3:Eu 2+ phosphor. In this study, the possibility of the thermal ionization process was investigated using thermoluminescence (TL) and persistent luminescence (PersL) spectroscopy.…”

Section: Introductionmentioning

confidence: 96%

Thermal Quenching Mechanism of CaAlSiN3:Eu2+ Red Phosphor

Ueda

Tanabe

Takahashi

et al. 2017

Bulletin of the Chemical Society of Japan

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CaAlSiN3:Eu 2+ is a widely applied phosphor in white LEDs (w-LEDs) because of strong blue absorption and efficient red luminescence.The good stability against thermal quenching has been well established, but the mechanism for the luminescence quenching at high temperatures has not been elucidated yet. In this report, we investigate the possibility of thermal ionization quenching by thermoluminescence (TL) and persistent luminescence techniques. In the TL glow curve by UV charging at 100 K, two broad TL glow bands were observed around 160 and 390 K. The higher TL glow band was not observed by 550 nm charging at 300 K, but it was observed by charging at 400 K, which corresponds to the onset temperature of luminescence quenching. Because the 550 nm light excites the lowest 5d level of Eu 2+ , we conclude that the luminescence quenching of CaAlSiN3:Eu 2+ at high temperatures is caused by the thermal ionization.

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“…The discovery of new systems is significant to enrich the knowledge of the CT phenomenon. The excitation energy of O 2– –Eu 3+ CT depends on the bond length of Eu 3+ –O 2– : as the bond length of Eu 3+ –O 2– is longer, the repulsion of the electrons between Eu 3+ and O 2– weakens, resulting in lower CT excitation energy and vice versa . This principle is considered to be applicable for O 2– –Ce 4+ CT also.…”

Section: Introductionmentioning

confidence: 99%

Ce⁴⁺-Based Compounds Capable of Photoluminescence by Charge Transfer Excitation under Near-Ultraviolet–Visible Light

et al. 2018

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Ce 4+ -based charge transfer phosphor is not common and has been reported mainly in Sr 2 CeO 4 with an excitation band peaking at ∼290 nm, mismatching with the near-ultraviolet light emitting diodes. Herein, we report a new series of Ce 4+based compounds Sr 4.4 Ce 2.6 REZnO 12 (RE = Y, La, and Eu) capable of photoluminescence induced by O 2− −Ce 4+ charge transfer excitation under near-ultraviolet−visible light. The crystal structure of Sr 4.4 Ce 2.6 EuZnO 12 was determined by single crystal X-ray diffraction. The RE = La and Y samples were confirmed to be iso-structure compounds of the RE = Eu sample by powder X-ray diffraction. By introducing highly covalent Zn 2+ −O 2− bonds into the framework, the Ce 4+ −O 2− bonds are lengthened due to the effect of the Ce 4+ −O 2− −Zn 2+ stretch. The lengthened Ce 4+ −O 2− bond weakens the repulsion of the electrons between Ce 4+ and O 2− , thereby lowering the charge transfer energy to the visible light region. Incorporation of Eu 3+ into the present compounds realized red emission under near-ultraviolet−visible excitation by the O 2− −Ce 4+ charge transfer followed by energy transfer to Eu 3+ .

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Evidence of three different Eu2+ sites and their luminescence quenching processes in CaAl2O4:Eu2+

Cited by 19 publications

References 38 publications

Crystal structure, photoluminescence and cathodoluminescence of Ba_1-xCa_xAl₂O₄ doped with Eu²⁺

Crystal structure, photoluminescence and cathodoluminescence of Ba_1-xCa_xAl₂O₄ doped with Eu²⁺

Thermal Quenching Mechanism of CaAlSiN3:Eu2+ Red Phosphor

Ce⁴⁺-Based Compounds Capable of Photoluminescence by Charge Transfer Excitation under Near-Ultraviolet–Visible Light

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Evidence of three different Eu2+ sites and their luminescence quenching processes in CaAl2O4:Eu2+

Cited by 19 publications

References 38 publications

Crystal structure, photoluminescence and cathodoluminescence of Ba1-xCaxAl2O4 doped with Eu2+

Crystal structure, photoluminescence and cathodoluminescence of Ba1-xCaxAl2O4 doped with Eu2+

Thermal Quenching Mechanism of CaAlSiN3:Eu2+ Red Phosphor

Ce4+-Based Compounds Capable of Photoluminescence by Charge Transfer Excitation under Near-Ultraviolet–Visible Light

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Crystal structure, photoluminescence and cathodoluminescence of Ba_1-xCa_xAl₂O₄ doped with Eu²⁺

Crystal structure, photoluminescence and cathodoluminescence of Ba_1-xCa_xAl₂O₄ doped with Eu²⁺

Ce⁴⁺-Based Compounds Capable of Photoluminescence by Charge Transfer Excitation under Near-Ultraviolet–Visible Light