Ho^3+-doped ZnO nano phosphor for low-threshold sharp red light emission at elevated temperatures

Fabitha, K.; Rao, M. S. Ramachandra

doi:10.1364/josab.34.002485

Cited by 20 publications

(7 citation statements)

References 28 publications

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“…After the substitution of Ln 3+ for Ca 2+ , the unit cell parameters will change, which may be conducive to the 4f configuration mixed with more opposite parity symmetry, weakening the forbidden selection rule, thereby enhancing the excitation and emission intensity. However, the different degree of lifting of the forbidden selection rule for each 4f–4f transition will result in different increases in the intensity of each transition with increasing concentration of the substituted ion . In conclusion, the greater radius difference between La 3+ and Ca 2+ compared to Y 3+ ions have a stronger effect on the crystal field, and thus the enhancement effect of La 3+ may also be more significant.…”

Section: Resultsmentioning

confidence: 93%

“…However, the different degree of lifting of the forbidden selection rule for each 4f−4f transition will result in different increases in the intensity of each transition with increasing concentration of the substituted ion. 54 In conclusion, the greater radius difference between La 3+ and Ca 2+ compared to Y 3+ ions have a stronger effect on the crystal field, and thus the enhancement effect of La 3+ may also be more significant. According to the above formulas 3 and 4, the average lifetimes of Ca 1 8 .…”

Section: Figure 1a and C Show The Xrd Patterns Of Camentioning

confidence: 84%

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Effect of Partial Ca²⁺ Substitution with Ln³⁺ (Ln = Y, La) on Luminescence Enhancement of Ca_18.62Zn₂(PO₄)₁₄:0.38Dy³⁺ White-Emitting Phosphor for White Light-Emitting Diodes

Huang

Wang

Zhang

et al. 2021

ACS Appl. Electron. Mater.

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A sequence of white-emitting Ca18.62–x Ln x Zn2(PO4)14:0.38Dy3+ (Ln = Y, La) phosphors were synthesized by a high-temperature solid-phase method. The luminescence enhancement of Ca18.62–x Ln x Zn2(PO4)14:0.38Dy3+ phosphors via Ln3+ partial substitution was investigated. Since Ln3+ and Ca2+ ions have similar ionic radii, XRD results showed that Ln3+ could enter into the lattice without changing the host structure and the luminescence performance was further enhanced by affecting the lattice environment around the luminescence center. When the substitution amounts of Y3+ and La3+ were respectively x = 0.57 and 0.76 in the Ca18.62–x Ln x Zn2(PO4)14:0.38Dy3+ phosphor, the optimal luminescence performance could be acquired, and the luminescence intensity could be increased to 1.43 and 1.55 times the original intensity, respectively. Meanwhile, the cation substitution can greatly improve the thermal stability and enhance the activation energy of phosphor. Finally, the w-LEDs with neutral white light emitting were obtained by coating the as-prepared phosphor on an n-UV chip, and the color rendering index and correlated color temperature were measured as 85.8 and 5071 K, respectively. All the results indicated that the Ca18.62–x Ln x Zn2(PO4)14:0.38Dy3+ phosphor is an excellent candidate as a single-component white-emitting phosphor.

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Section: Resultsmentioning

confidence: 93%

Section: Figure 1a and C Show The Xrd Patterns Of Camentioning

confidence: 84%

Effect of Partial Ca²⁺ Substitution with Ln³⁺ (Ln = Y, La) on Luminescence Enhancement of Ca_18.62Zn₂(PO₄)₁₄:0.38Dy³⁺ White-Emitting Phosphor for White Light-Emitting Diodes

Huang

Wang

Zhang

et al. 2021

ACS Appl. Electron. Mater.

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“…To surmount this problem, the concentration of Sm 3+ is restricted to 1 mol% and the non equilibrium laser ablation technique which involves very high energy will be beneficial as it can support the formation of complicated stoichiometry. The targets were made from powder sample synthesized by sol-gel route [33], preferred to ensure the uniform distribution of the dopant in the host matrix. The sol-gel derived fine powder has been then pressed in the form of pellets and sintered at a temper ature of 1100 °C for for a duration of 12 h.…”

Section: Micro-sphere Fabricationmentioning

confidence: 99%

“…It is evident that the undoped ZnO microsphere does not have any noticeable emission peaks compared to that of Sm 3+ :ZnO micro-spheres in the given spectral range as the 4f levels are absent and thus the corre sponding transitions are not occurred. Figure 5(b) depicts the different atomic interactions leading to the energy level splitting in Sm 3+ [33,41]. For the [Xe]4f 5 configuration of Sm 3+ and according to Hund's rule, the ground state of Sm 3+ is 6 H 5/2 .…”

Section: Photoluminescence Studiesmentioning

confidence: 99%

Realization of sharp visible WGM lasing from Sm³⁺ :ZnO micro-spheres fabricated by laser ablation technique

Fabitha

Wakiyama

Oshima

et al. 2020

J. Phys. D: Appl. Phys.

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In this paper, the whispering gallery mode lasing from Sm 3+ doped ZnO micro-spheres operating in the visible wavelength range 550-750 nm is studied. Highly smooth and crystalline Sm 3+ :ZnO micro-spheres of various diameters were synthesized by simple laser ablation of sintered target in air. The dopant concentration has been restricted within the solid solubility limit of 1 mol%. The Sm 3+ ion substitution in ZnO matrix results in the formation of inter-band levels by the characteristic 4f level of Sm 3+ in the forbidden gap of ZnO. Thus, when the micro-spheres are excited with 488 nm, four major visible emissions associated with Sm 3+ f − f transitions namely, transitions from 4 G 5/2 to its low-lying multiplets of 6 H J (J = 5/2, 7/2, 9/2 and 11/2), are obtained. These emissions are coupled to the WGMs of the Sm 3+ :ZnO micro-cavity resulting in sharp resonances in the visible region. Interestingly, the resonances are found to be lasing above lower pumping powers. The Q-factor obtained is of the order of 10 3 for spheres of size ranging 1.8-10.2 µm. The best Q-factor obtained is 3744 for 561.61 nm peak (FWHM 0.15 nm) from 8 µm sphere. These results would find a place in visible range lasing and sensor applications.

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“…The singular advantage of this platform is the fact that the bandgap of ZnO can be easily engineered by introducing dopants into this host matrix, particularly in the form of metals with similar ionic radii such as Mg, Al, Cr and Ni to name a few [17][18][19][20][21][22]. Mg-doping in ZnO tunes the bandgap towards the UV region and induces higher exciton binding energies.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Pulse Ablation Assisted Mg-ZnO Nanoparticles for UV-Only Emission

et al. 2020

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The need for improved UV emitting luminescent materials underscored by applications in optical communications, sterilization and medical technologies is often addressed by wide bandgap semiconducting oxides. Among these, the Mg-doped ZnO system is of particular interest as it offers the opportunity to tune the UV emission by engineering its bandgap via doping control. However, both the doped system and its pristine congener, ZnO, suffer from being highly prone to parasitic defect level emissions, compromising their efficiency as light emitters in the ultraviolet region. Here, employing the process of femtosecond pulsed laser ablation in a liquid (fs-PLAL), we demonstrate the systematic control of enhanced UV-only emission in Mg-doped ZnO nanoparticles using both photoluminescence and cathodoluminescence spectroscopies. The ratio of luminescence intensities corresponding to near band edge emission to defect level emission was found to be six-times higher in Mg-doped ZnO nanoparticles as compared to pristine ZnO. Insights from UV-visible absorption and Raman analysis also reaffirm this defect suppression. This work provides a simple and effective single-step methodology to achieve UV-emission and mitigation of defect emissions in the Mg-doped ZnO system. This is a significant step forward in its deployment for UV emitting optoelectronic devices.

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Ho^3+-doped ZnO nano phosphor for low-threshold sharp red light emission at elevated temperatures

Cited by 20 publications

References 28 publications

Effect of Partial Ca²⁺ Substitution with Ln³⁺ (Ln = Y, La) on Luminescence Enhancement of Ca_18.62Zn₂(PO₄)₁₄:0.38Dy³⁺ White-Emitting Phosphor for White Light-Emitting Diodes

Effect of Partial Ca²⁺ Substitution with Ln³⁺ (Ln = Y, La) on Luminescence Enhancement of Ca_18.62Zn₂(PO₄)₁₄:0.38Dy³⁺ White-Emitting Phosphor for White Light-Emitting Diodes

Realization of sharp visible WGM lasing from Sm³⁺ :ZnO micro-spheres fabricated by laser ablation technique

Femtosecond Pulse Ablation Assisted Mg-ZnO Nanoparticles for UV-Only Emission

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Ho^3+-doped ZnO nano phosphor for low-threshold sharp red light emission at elevated temperatures

Cited by 20 publications

References 28 publications

Effect of Partial Ca2+ Substitution with Ln3+ (Ln = Y, La) on Luminescence Enhancement of Ca18.62Zn2(PO4)14:0.38Dy3+ White-Emitting Phosphor for White Light-Emitting Diodes

Effect of Partial Ca2+ Substitution with Ln3+ (Ln = Y, La) on Luminescence Enhancement of Ca18.62Zn2(PO4)14:0.38Dy3+ White-Emitting Phosphor for White Light-Emitting Diodes

Realization of sharp visible WGM lasing from Sm3+ :ZnO micro-spheres fabricated by laser ablation technique

Femtosecond Pulse Ablation Assisted Mg-ZnO Nanoparticles for UV-Only Emission

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Effect of Partial Ca²⁺ Substitution with Ln³⁺ (Ln = Y, La) on Luminescence Enhancement of Ca_18.62Zn₂(PO₄)₁₄:0.38Dy³⁺ White-Emitting Phosphor for White Light-Emitting Diodes

Effect of Partial Ca²⁺ Substitution with Ln³⁺ (Ln = Y, La) on Luminescence Enhancement of Ca_18.62Zn₂(PO₄)₁₄:0.38Dy³⁺ White-Emitting Phosphor for White Light-Emitting Diodes

Realization of sharp visible WGM lasing from Sm³⁺ :ZnO micro-spheres fabricated by laser ablation technique