EPR and optical investigations of LaMgAl 11 O 19 :Cr 3+ phosphor

Singh, Vijay; Sivaramaiah, G.; Rao, J.L.; Kim, S.H.

doi:10.1016/j.materresbull.2014.08.038

Cited by 58 publications

(24 citation statements)

References 25 publications

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“…The spectra of these slightly doped systems exhibit distinguishable near-edge absorption peaks, which lie at the origin of such misleading edge assignment. In fact, these absorption features (red arrows) are brought by Cr 6+ characteristic optical transitions commonly found at ~ 338 and ~ 370 nm, and are assigned to 4 A2g→ 4 T1g and to 4 A2g→ 2 A1g transition, respectively [1][2][3][4][33][34][35][36][37]. Actually, Cr 6+ is optically inactive since it has 3d 0 configuration, but the charge transfer taking place between O and Cr ions leads to the optically active Cr 5+ (3d 1 2p 5 ) state [1][2][3][38][39][40][41].…”

Section: Optical Absorption Resultsmentioning

confidence: 99%

Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

Slibi

Hassan

El-Fattah

et al. 2021

Preprint

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The melt-quenching technique was used to prepare a series of chromium-doped borate glasses with the composition xCr2O3 - (70-x) B2O3- 30 Li2O- (x = 0, 0.1, 0.2, 0.3 and 0.5 mol %). The low-doping level here employed allowed to unambiguously identify well-defined near-edge Cr6+ optical transitions, and to precisely determine the optical band gap of the borate glass host. Additional Cr3+ transitions were observed in the visible regime, rendering a strong modulation of the glass color, from colorless to dark greenish, with Cr content. Both Cr6+(after the charge transfer transformation into Cr5+) and Cr3+oxidation states and their variations with Cr doping were identified from electron spin resonance spectroscopy. All samples exhibit similar vibrational spectra dominated by BO3 and BO4 structural units, with the development of weak Cr6+ vibration with Cr doping. The present study provides structurally similar but optically active and tunable glass hosts suitable for various optical applications.

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Section: Optical Absorption Resultsmentioning

confidence: 99%

Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

Slibi

Hassan

El-Fattah

et al. 2021

Preprint

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show abstract

Section: Optical Absorption Resultsmentioning

confidence: 99%

Optical transitions from hexavalent chromium in lithium-borate glasses

et al. 2021

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The melt-quenching technique was used to prepare a series of chromium-doped borate glasses with the composition xCr2O3 -(70-x) B2O3-30 Li2O-(x = 0, 0.1, 0.2, 0.3 and 0.5 mol %). The low-doping level here employed allowed to unambiguously identify welldefined near-edge Cr 6+ optical transitions, and to precisely determine the optical band gap of the borate glass host. Additional Cr 3+ transitions were observed in the visible regime, rendering a strong modulation of the glass color, from colorless to dark greenish, with Cr content. Both Cr 6+ (after the charge transfer transformation into Cr 5+ ) and Cr 3+ oxidation states and their variations with Cr doping were identified from electron spin resonance spectroscopy. All samples exhibit similar vibrational spectra dominated by BO3 and BO4 structural units, with the development of weak Cr 6+ vibration with Cr doping. The present study provides structurally similar but optically active and tunable glass hosts suitable for various optical applications.

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“…Characteristic emission bands in red and in the near‐infrared (NIR) range associated with d–d electronic transitions of Cr 3+ have been reported previously in many phosphors. Sharp deep‐red emissions near 700 nm in Ca 3 Al 2 Ge 2 O 10 :Cr 3+ , Ca 14 Zn 6 Ga 10 O 35 :Cr 3+ , LaMgAl 11 O 19 :Cr 3+ and BaAl 2 O 4 :Cr 3+ can be observed, while Cr 3+ ‐doped MWO 4 (M = Mg, Zn, Cd) and YGG exhibit broad NIR emission at 10 K or 77 K. LiMgAl(MoO 4 ) 3 :Cr 3+ , KSc(WO 4 ) 2 :Cr 3+ and β‐Ga 2 O 3 :Cr 3+ phosphors all generate broad NIR emissions at room temperature that show potential application in tunable laser medium and bio‐imaging.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and luminescence of novel near‐infrared emitting BaZrSi₃O₉:Cr³⁺ phosphors

et al. 2017

Luminescence

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The BaZrSi O :Cr phosphors were prepared by a high temperature solid state method. Their structures were confirmed with XRD and their luminescence properties were investigated. Under excitation at 455 nm, BaZrSi O :Cr phosphors exhibited a broad near infrared emission band peaked at 800 nm, which was assigned to the T → A transition of Cr . The near infrared emission intensity reached a maximum at Cr concentration of 0.7%. There was a concentration quenching phenomenon of Cr in BaZrSi O matrix and the corresponding concentration quenching mechanism was investigated. With efficient near infrared emission in the range of 700-1000 nm, BaZrSi O :Cr phosphors may find applications in solar energy conversion.

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EPR and optical investigations of LaMgAl 11 O 19 :Cr 3+ phosphor

Cited by 58 publications

References 25 publications

Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

Optical transitions from hexavalent chromium in lithium-borate glasses

Synthesis and luminescence of novel near‐infrared emitting BaZrSi₃O₉:Cr³⁺ phosphors

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EPR and optical investigations of LaMgAl 11 O 19 :Cr 3+ phosphor

Cited by 58 publications

References 25 publications

Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

Optical Transitions from Hexavalent Chromium in Lithium-Borate Glasses

Optical transitions from hexavalent chromium in lithium-borate glasses

Synthesis and luminescence of novel near‐infrared emitting BaZrSi3O9:Cr3+ phosphors

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Synthesis and luminescence of novel near‐infrared emitting BaZrSi₃O₉:Cr³⁺ phosphors