Electronic structure and luminescence assets in white-light emitting Ca2V2O7, Sr2V2O7 and Ba2V2O7 pyro-vanadates: X-ray absorption spectroscopy investigations

Sharma, Aditya; Varshney, Mayora; Chae, Keun Hwa; Won, Sung Ok

doi:10.1039/c8ra03347a

Cited by 39 publications

(29 citation statements)

References 45 publications

(110 reference statements)

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“…At room temperature SrCO 3 (the only visible peak is at 1070 cm −1 ) and V 2 O 5 (accounting for the remaining peaks) are present, as expected 49,50 . In addition to the SrCO 3 and V 2 O 5 precursors, Sr 2 V 2 O 7 (250, 350, 580, 700, 840, 880 cm −1 ) has formed by 425°C 51 . At temperatures of 680°C and higher, only Sr 2 V 2 O 7 is visible.…”

Section: Resultsmentioning

confidence: 54%

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In situ defect quantification and phase identification during flash sintering using Raman spectroscopy

Murray

Sulekar

et al. 2021

J. Am. Ceram. Soc.

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Flash sintering has been established as a method to rapidly densify or induce phase transformation in materials by applying an electric field. Understanding rapid transformations is challenging in a laboratory setting, where phase and defect populations may change with sub-second time scales. In this work, we apply in situ Raman spectroscopy to investigate defect complexes and phase transformations during flash sintering. We demonstrate that the oxygen vacancy complexes in Ce 0.85 Gd 0.15 O 1.925 and the evolving phases in a SrCO 3 + V 2 O 5 reaction can be probed with acquisition times sufficient to monitor stage II of flash sintering. We establish how thermal effects can be separated from effects of the electric field and determine the resolution of the defect concentration. The fast characterization we demonstrate here can be combined with well-developed models of thermal and phase evolution to elucidate the mechanism of densification during flash sintering.

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Section: Resultsmentioning

confidence: 54%

“…49,50 In addition to the SrCO 3 and V 2 O 5 precursors, Sr 2 V 2 O 7 (250, 350, 580, 700, 840, 880 cm −1 ) has formed by 425°C. 51 At temperatures of 680°C and higher, only Sr 2 V 2 O 7 is visible. Upon cooling, Sr 3 V 2 O 8 (330, 785, 855 cm −1 ) forms in addition to the Sr 2 V 2 O 7 that formed during heating.…”

Section: Monitoring Phase Transformationsmentioning

confidence: 97%

In situ defect quantification and phase identification during flash sintering using Raman spectroscopy

Murray

Sulekar

et al. 2021

J. Am. Ceram. Soc.

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“…The first absorption feature between 5465 and 5475 eV was ascribed to the pre-edge peak owing to the transition of the 1s core level to the 3d states. It was a dipole-prohibited transition, but initiated by the combination of strong 3d-4p mixing and the node of the metal 3d orbitals with the surrounding O 2p orbitals [25]. The lesser intensity of pre-edge peak was ascribed to the more symmetric VO6 octahedra in the substituted compounds [26].…”

Section: Resultsmentioning

confidence: 99%

Spinel rGO Wrapped CoV2O4 Nanocomposite as a Novel Anode Material for Sodium-Ion Batteries

Muruganantham

Liu

2020

Polymers

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Binary mixed transition-based metal oxides have some of the most potential as anode materials for rechargeable advanced battery systems due to their high theoretical capacity and tremendous electrochemical performance. Nonetheless, binary metal oxides still endure low electronic conductivity and huge volume expansion during the charge/discharge processes. In this study, we synthesized a reduced graphene oxide (rGO)-wrapped CoV2O4 material as the anode for sodium ion batteries. The X-ray diffraction analyses revealed pure-phased CoV2O4 (CVO) rGO-wrapped CoV2O4 (CVO/rGO) nanoparticles. The capacity retention of the CVO/rGO composite anode demonstrated 81.6% at the current density of 200 mA/g for more than 1000 cycles, which was better than that of the bare one of only 73.5% retention. The as-synthesized CVO/rGO exhibited remarkable cyclic stability and rate capability. The reaction mechanism of the CoV2O4 anode with sodium ions was firstly studied in terms of cyclic voltammetry (CV) and ex situ XRD analyses. These results articulated the manner of utilizing the graphene oxide-coated spinel-based novel anode-CoV2O4 as a potential anode for sodium ion batteries.

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“…1 T 2 transition. [21,29] Furthermore, doping of the Eu 3+ ion increased the intensity of optical absorption in the UV region. Intensity of absorption reached maximum at concentration x = 0.02% for Eu 3+ ions and decreased at higher concentrations.…”

Section: Uv-visible Spectral Analysismentioning

confidence: 99%

“…This broad band luminescence in the visible region can be used to obtain good colour-rending properties for light devices. [21] Previous studies have shown that the Ln 3+ ion could be co-doped with inorganic compounds such as M 2 V 2 O 7 :Ln 3+ phosphors. Jaianfeng Gu and colleagues synthesized Ca 2 V 2 O 7 :Eu 3+ using a hydrothermal process and reported that the reaction time and morphology had greatly influenced the optical properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of a Eu³⁺‐activated Ba_2–xV₂O₇:xEu³⁺ phosphor using a hydrothermal method: a potential material for near‐UV‐WLED applications

Bharathi¹,

Jeyakumaran²,

Ramaswamy³

et al. 2021

Luminescence

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Eu 3+ -activated Ba 2 V 2 O 7 (Ba 2-x V 2 O 7 :xEu 3+ ) phosphor materials were synthesized using a hydrothermal method and different concentrations of europium (x = 0.01, 0.02, 0.03, 0.04, and 0.05%). Phase purity, structural, morphological, optical, and luminescence characteristics of the as-synthesized phosphors were studied using powder X-ray diffraction (XRD), high resolution scanning electron microscopy, UV-visible spectroscopy, and fluorescence spectrometry. The recorded XRD patterns of the as-synthesized phosphors were indexed and predicted to be a triclinic structure. A cube-like morphology was obtained for the as-prepared samples. Broad absorption in the UV region from 200 nm to 380 nm was observed and the good transparency in the visible region at 400-800 nm originated from the [VO 4 ] 3− group charge transfer (CT) transition. The broad emission peak centred at 499 nm was due to the CT band of the [VO 4 ] 3− group. Also, a sharp peak observed at 613 nm was due to the electric dipole transition of 5 D 0 ! 7 F 2 of Eu 3+ ions that occupied the lattice sites without inversion symmetry for all concentrations. The colour qualities of the as-prepared samples were calculated using Commission International de l'Eclairage coordinates. The colour-rending index (CRI) value was 86 for the Ba 1.97 V 2 O 7 :0.03Eu 3+ phosphor. Furthermore, a WLED with a high CRI value of 95 was achieved by coupling the 3 W 356 nm near-UV light-emitting diode (LED) chip with the Ba 2-x V 2 O 7 :xEu 3+ phosphor. These results suggested that the as-prepared phosphor materials are potential candidates for fabrication of near-UV chip excited WLEDs.

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Electronic structure and luminescence assets in white-light emitting Ca₂V₂O₇, Sr₂V₂O₇ and Ba₂V₂O₇ pyro-vanadates: X-ray absorption spectroscopy investigations

Abstract: Chemically synthesized pyro-vanadates exhibit sub-pentavalent V ions and white-light emission via charge transfer transitions of VO4 tetrahedra.

Cited by 39 publications

References 45 publications

In situ defect quantification and phase identification during flash sintering using Raman spectroscopy

In situ defect quantification and phase identification during flash sintering using Raman spectroscopy

Spinel rGO Wrapped CoV2O4 Nanocomposite as a Novel Anode Material for Sodium-Ion Batteries

Synthesis and characterization of a Eu³⁺‐activated Ba_2–xV₂O₇:xEu³⁺ phosphor using a hydrothermal method: a potential material for near‐UV‐WLED applications

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Electronic structure and luminescence assets in white-light emitting Ca2V2O7, Sr2V2O7 and Ba2V2O7 pyro-vanadates: X-ray absorption spectroscopy investigations

Abstract: Chemically synthesized pyro-vanadates exhibit sub-pentavalent V ions and white-light emission via charge transfer transitions of VO4 tetrahedra.

Cited by 39 publications

References 45 publications

In situ defect quantification and phase identification during flash sintering using Raman spectroscopy

In situ defect quantification and phase identification during flash sintering using Raman spectroscopy

Spinel rGO Wrapped CoV2O4 Nanocomposite as a Novel Anode Material for Sodium-Ion Batteries

Synthesis and characterization of a Eu3+‐activated Ba2–xV2O7:xEu3+ phosphor using a hydrothermal method: a potential material for near‐UV‐WLED applications

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Electronic structure and luminescence assets in white-light emitting Ca₂V₂O₇, Sr₂V₂O₇ and Ba₂V₂O₇ pyro-vanadates: X-ray absorption spectroscopy investigations

Synthesis and characterization of a Eu³⁺‐activated Ba_2–xV₂O₇:xEu³⁺ phosphor using a hydrothermal method: a potential material for near‐UV‐WLED applications