Oxygen-impurity charge transfer in NaMgF3:Ln (Ln = Yb, Sm, or Eu): Establishing the lanthanide energy levels in NaMgF3

Schuyt, J.J.; Williams, G. V. M.

doi:10.1016/j.jlumin.2019.04.004

Cited by 20 publications

(44 citation statements)

References 30 publications

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“…Schuyt and William, 24 based on the Tanner diagram, 72 suggested that the Eu 3+ occupies sites with C s , C nv or C n symmetry because the 5 D 0 -7 F 0 transition is presented in the emission spectrum. C s is part of low symmetry groups, which is not the case here because the 7 F 1 splitting is less than 350 cm -1 (Ref.…”

Section: F 1 State Energy Sublevels Of the Eu 3+ Ionmentioning

confidence: 99%

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Defect clustering in an Eu-doped NaMgF₃ compound and its influence on luminescent properties

2021

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Section: F 1 State Energy Sublevels Of the Eu 3+ Ionmentioning

confidence: 99%

“…21,22 Furthermore, lanthanide ions doped into NaMgF 3 polycrystalline samples have also been prepared by the conventional solid-state reaction method. 23,24 In fact, lanthanide incorporation in compounds has been largely used to enhance luminescent properties.…”

Section: Introductionmentioning

confidence: 99%

Defect clustering in an Eu-doped NaMgF₃ compound and its influence on luminescent properties

2021

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“…Usually, the quenching temperature for Yb 2+ emission is low but in NaMgF 3 , quenching is observed even at room temperature. The luminescence of trivalent rare earths such as Ce 3+ , [ 21 ] Pr 3+ , [ 22,23 ] Yb 3+ , Er 3+ , [ 24,25 ] Gd 3+ , [ 26 ] Eu 3+ , [ 27 ] Sm 3+ , [ 28 ] Dy 3+[ 29 ] has also been reported. NaMgF 3 :Yb 3+ , Er 3+ are good candidate host materials for red upconversion luminescence.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization, and luminescence studies of rare‐earth‐activated NaMgF₃

Singh¹,

Belsare²,

Moharil

2021

Luminescence

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NaMgF3‐based phosphors have been described frequently in the literature. Their synthesis faces difficulties typical of fluoride materials. A simple precipitation synthesis for NaMgF3‐based phosphors is described in this paper. This consisted of mixing aq. NaF and MgCl2/MgSO4 solutions. Various activators could be incorporated by adding the required salts during this process. Characteristic emission of the activators was observed in the prepared phosphors. As‐prepared samples exhibited predominantly trivalent lanthanide emission. After thermal treatment in a reductive atmosphere, europium‐doped samples showed the intense emission of Eu2+. By virtue of the intense nature of the emission, lifetime measurements could be made for this sample. Notably, intense thermoluminescence and optically stimulated luminescence were observed in NaMgF3:Eu. A simple, fast method for the synthesis of NaMgF3 was therefore developed.

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“…LiF and silver-doped phosphate glasses are the most widely used RPL materials [10,167]. RPL has been observed in several Ln-doped NaMgF3 materials, where on X-ray stimulation, electrons were trapped at the Ln 3+ sites resulting in radiation-induced valence conversions, for example, in NaMgF3:Sm (Sm 3+ → Sm 2+ ) [21] and NaMgF3:Yb (Yb 3+ → Yb 2+ ) [168]. The stability of this conversion is proportional to the energy difference between the ground state of the Ln 2+ ion and the CB of the host.…”

Section: Luminescence Phenomenonmentioning

confidence: 99%

“…The stability of this conversion is proportional to the energy difference between the ground state of the Ln 2+ ion and the CB of the host. For example, the Yb 2+ ground state has been reported at ~4.86 eV below the CB in NaMgF3:Yb [168]. Hence Yb 3+ acts as a highly stable electron trap.…”

Section: Luminescence Phenomenonmentioning

confidence: 99%

The Luminescence of Lanthanide-doped NaMgF3 Nanoparticles: Radioluminescence, Radiophotoluminescence and Optically Stimulated Luminescence

Nalumaga¹

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NaMgF3 is a host material that has demonstrated luminescent properties suitable for radiation dose measurements when doped with lanthanide (Ln) ions. NaMgF3 has a response to ionising radiation similar to that of tissue, and hence it has potential application in radiotherapy where a high level of accuracy is required. This thesis focused on investigations into the suitability of NaMgF3 nanoparticles for radiation dose measurements. Nanoparticles display advantages that can be exploited to increase spatial resolution in two-dimensional dosimetry. Additionally, nanoparticles exhibit new and different distributions of optically active traps, and their luminescence can be sensitised to increase the signal to noise. Hence, this thesis presents results obtained from the synthesis and characterisation of Ln-doped NaMgF3 nanoparticles. The nanoparticles were synthesised via the hydrothermal, reverse micelle and thermolysis techniques. Structural studies were carried out, followed by investigations on the effect of X-ray irradiation on the luminescent properties of the nanoparticles. It was observed that compared to the bulk materials, the nanoparticles exhibited increased oxygen (O2-)-related defect luminescence and favoured substitution of trivalent ions over the divalent ions. The behaviour was attributed to the stability of trivalent ions in aqueous solutions during nanoparticle synthesis, which encouraged increased incorporation of O2--related defects to create charge neutrality. O2--related defects allowed for O2- → Yb3+ charge transfer process, hence Yb3+ emission in the infrared region. X-ray stimulation resulted in Yb3+ → Yb2+ radiophotoluminescence (RPL), but the increase in Yb-dopant concentration revealed no significant effect on the structural and luminescent properties. Most of the studied materials exhibited multiple luminescence properties for monitoring radiation doses, which would increase the dose accuracy. Ce-doped nanoparticles exhibited the first reported optically stimulated luminescence (OSL) in Ln-doped near tissue-equivalent NaMgF3 nanoparticles suitable for total radiation measurements. OSL occurred through a series of processes, including the creation of F-centres through X-ray irradiation and optical stimulation to release electrons that recombined with holes trapped at Ce4+ sites, followed by Ce3+ emission. In addition, the Ce3+ → Ce4+ RPL effect suitable for cumulative radiation monitoring was observed from isolated and aggregated Ce3+ sites in the Ce-doped nanoparticles, providing an additional method to increase dose accuracy. Furthermore, the Ce,Sm co-doped NaMgF3 nanoparticles demonstrated suitability for real-time and cumulative radiation dose monitoring via Sm radioluminescence after a priming dose and multiple Ce3+ → Ce4+, Sm3+ → Sm2+, and O2- → O- RPL signals through which cumulative radiation doses can be determined. Finally, the applicability of singly doped oleic acid-capped NaMgF3:Eu and NaMgF3:Sm nanoparticles for radiation monitoring via the Eu3+ → Eu2+ and Sm3+ → Sm2+ RPL effects were demonstrated. The studies were followed by investigations of the sensitisation of Eu3+ and Sm3+ luminescence signals using 2-thenoyltrifluoroacetone (TTFA). The first successful sensitisation of NaMgF3 nanoparticles was demonstrated through remarkable TTFA → Eu3+ energy transfer. However, minimal TTFA → Sm3+ sensitisation was observed, attributable to a non-optimal energy difference between the TTFA triplet state and the Sm3+ resonance energy level, encouraging back energy transfer. TTFA → O2- sensitisation was additionally observed in the NaMgF3:Sm nanoparticles. Furthermore, enhancement of Sm3+ luminescence was additionally demonstrated in the Ce,Sm co-doped nanoparticles via energy transfer from the Ce3+ fully allowed 4f → 5d transitions. The studies resulted in a wealth of information, and where possible, detailed schematic models are presented to explain the observations, which will guide future research. Ultimately, nanoparticles display luminescent properties suitable for dosimetry applications, and the results encouraged further research into the application of nanoparticles as dosimeter materials.

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Oxygen-impurity charge transfer in NaMgF3:Ln (Ln = Yb, Sm, or Eu): Establishing the lanthanide energy levels in NaMgF3

Cited by 20 publications

References 30 publications

Defect clustering in an Eu-doped NaMgF₃ compound and its influence on luminescent properties

Defect clustering in an Eu-doped NaMgF₃ compound and its influence on luminescent properties

Synthesis, characterization, and luminescence studies of rare‐earth‐activated NaMgF₃

The Luminescence of Lanthanide-doped NaMgF3 Nanoparticles: Radioluminescence, Radiophotoluminescence and Optically Stimulated Luminescence

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Oxygen-impurity charge transfer in NaMgF3:Ln (Ln = Yb, Sm, or Eu): Establishing the lanthanide energy levels in NaMgF3

Cited by 20 publications

References 30 publications

Defect clustering in an Eu-doped NaMgF3 compound and its influence on luminescent properties

Defect clustering in an Eu-doped NaMgF3 compound and its influence on luminescent properties

Synthesis, characterization, and luminescence studies of rare‐earth‐activated NaMgF3

The Luminescence of Lanthanide-doped NaMgF3 Nanoparticles: Radioluminescence, Radiophotoluminescence and Optically Stimulated Luminescence

Contact Info

Product

Resources

About

Defect clustering in an Eu-doped NaMgF₃ compound and its influence on luminescent properties

Defect clustering in an Eu-doped NaMgF₃ compound and its influence on luminescent properties

Synthesis, characterization, and luminescence studies of rare‐earth‐activated NaMgF₃