Charge transfer from Eu2+ to trivalent lanthanide co-dopants: Systematic behavior across the series

Joos, Jonas; Neefjes, Ivo; Seijo, Luis; Barandiarán, Zoila

doi:10.1063/5.0037992

Cited by 20 publications

(19 citation statements)

References 62 publications

(71 reference statements)

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“…It is worth noting that the initial and final states of this charge transfer are well known but that there is still no consensus on how this transfer is accomplished, [ 47–49,51 ] however it was recently shown that the electron transfer between Eu and Sm in CaF 2 is achieved directly without the involvement of conduction band states. [ 50,52 ] To verify the existence of similar valence changes in SrAl 2 O 4 :Eu 2+ ,Sm 3+ , as suggested by Equations (1) and (2) the phosphor was subjected to a similar X‐ray absorption spectroscopy experiment as described in Joos et al. [ 46 ] .…”

Section: Resultsmentioning

confidence: 99%

A Standalone, Battery‐Free Light Dosimeter for Ultraviolet to Infrared Light

Heggen

Žilėnaitė

Ezerskyte

et al. 2021

Adv Funct Materials

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Light sensors are widely used to monitor light intensities, for instance in medical applications, in agriculture or for conservation of art. Most of these sensors are electronic devices that record continuously but applications that only require information of integrated intensities, measured over a long time, could greatly benefit from an integrating dosimeter that does not require a power supply. In this work a wireless and quantitative light dosimeter is presented based on SrAl 2 O 4 :Eu 2+ ,Sm 3+ , a phosphor that exhibits stable energy storage upon exposure to blue and ultraviolet light. It is shown that a forward electron transfer from europium to samarium can be induced under illumination with blue or ultraviolet light while the reverse electron transfer can be achieved by illuminating the phosphors with green to infrared light. This reverse transfer is accomplished through excitation of the divalent samarium and results in bright, green optically stimulated luminescence. The stable energy storage, in combination with the possibility for optical read-out, makes SrAl 2 O 4 :Eu 2+ ,Sm 3+ ideally suited to be used as an integrating light dosimeter for monochromatic to broadband light, from the ultraviolet to the near infrared. To demonstrate this, a proof of concept dosimeter was developed in which this phosphor was successfully used to measure average daylight intensities.

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Section: Resultsmentioning

confidence: 99%

A Standalone, Battery‐Free Light Dosimeter for Ultraviolet to Infrared Light

Heggen

Žilėnaitė

Ezerskyte

et al. 2021

Adv Funct Materials

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“…Firstly, the density of luminescent activators (usually of the order of 1 mol%) is often greater than that of empty traps when they are crystallographic defects, making that activator-trap pairs are on average far apart. Secondly, multi-electron ab initio calculations have shown that electron transfer between activators and traps occurs locally, not requiring the delocalization of a charge carrier to a conduction band state [59,60]. Thirdly, empty traps can only be filled to a limited level by exciting the luminescent activators, even if the density of traps is high, as is the case of Dy in Sr 4 Al 14 O 25 :Eu 2+ ,Dy 3+ [58], making that electronhole pairs are thus far apart.…”

Section: Analytic Expressionmentioning

confidence: 99%

Revealing trap depth distributions in persistent phosphors with a thermal barrier for charging

Feng

Joos

et al. 2022

Phys. Rev. B

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The performance of persistent phosphors under given charging and working conditions is determined by the properties of the traps that are responsible for these unique properties. Traps are characterized by the height of their associated barrier for thermal detrapping, and a continuous distribution of trap depths is often found in real materials. Accurately determining trap depth distributions is hence of importance for the understanding and development of persistent phosphors. However, extracting the trap depth distribution is often hindered by the presence of a thermal barrier for charging as well, which causes a temperature-dependent filling of traps. For this case, we propose a method for extracting the trap depth distribution from a set of thermoluminescence (TL) curves obtained at different charging temperatures. The TL curves are first transformed into electron population functions via the Tikhonov regularization, assuming first-order kinetics. Subsequently, the occupation of the traps as a function of their depth, quantified by the so-called filling function, is obtained. Finally, the underlying trap depth distribution is reconstructed from the filling functions. The proposed method provides a substantial improvement in precision and resolution for the trap depth distribution compared with existing methods. This is hence a step forward in understanding the (de)trapping behavior of persistent and storage phosphors.

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“…Many more technological applications rely on electron transfer processes among dopants or with other crystallographic defects [21][22][23][24]. At the same time, electron transfer processes are known to limit the performance of luminescent materials when multiple valences coexist or when high excitation intensities are used [25][26][27][28][29][30]. This demonstrates that an in-depth understanding of the electron transfer is essential in developing the next generation luminescent materials, allowing one to amplify the functional behavior while suppressing the associated disadvantages.…”

mentioning

confidence: 99%

Elucidation of the electron transfer mechanism in Eu2+ and Sm3+ codoped
Joos
¹
,
Heggen
²
,
Amidani
³

et al. 2021
Phys. Rev. B
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19
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16
0
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Many-electron multiconfigurational ab initio calculations are combined with x-ray spectroscopy to scrutinize a popular model for electron transfer in lanthanide-doped crystals which hypothesizes that the electrons are conveyed by the conduction band of the host. Contrary to this accepted picture, our combined theoreticalexperimental effort shows that the reversible electron phototransfer from Eu 2+ to Sm 3+ in CaF 2 is direct, from metal to metal. It is theoretically predicted and experimentally verified that visible light induces the reverse electron transfer.

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Charge transfer from Eu2+ to trivalent lanthanide co-dopants: Systematic behavior across the series

Cited by 20 publications

References 62 publications

A Standalone, Battery‐Free Light Dosimeter for Ultraviolet to Infrared Light

A Standalone, Battery‐Free Light Dosimeter for Ultraviolet to Infrared Light

Revealing trap depth distributions in persistent phosphors with a thermal barrier for charging

Elucidation of the electron transfer mechanism in Eu2+ and Sm3+ codoped
Joos
¹
,
Heggen
²
,
Amidani
³

et al. 2021
Phys. Rev. B
Self Cite
19
1
16
0
View full text Add to dashboard Cite

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Charge transfer from Eu2+ to trivalent lanthanide co-dopants: Systematic behavior across the series

Cited by 20 publications

References 62 publications

A Standalone, Battery‐Free Light Dosimeter for Ultraviolet to Infrared Light

A Standalone, Battery‐Free Light Dosimeter for Ultraviolet to Infrared Light

Revealing trap depth distributions in persistent phosphors with a thermal barrier for charging

Elucidation of the electron transfer mechanism in Eu2+ and Sm3+ codoped Joos1, Heggen2, Amidani3 et al. 2021Phys. Rev. BSelf Cite191160View full textAdd to dashboardCite

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Elucidation of the electron transfer mechanism in Eu2+ and Sm3+ codoped
Joos
¹
,
Heggen
²
,
Amidani
³

et al. 2021
Phys. Rev. B
Self Cite
19
1
16
0
View full text Add to dashboard Cite