Electron–vibrational interaction in 4f–5d optical transitions in Ba, Ca, Sr thiogallates doped with Eu2+ ions

Nazarov, Maxim; Tsukerblat, Boris; Noh, Do Young

doi:10.1016/j.jlumin.2008.02.008

Cited by 43 publications

(21 citation statements)

References 23 publications

(31 reference statements)

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“…S, in turn, is directly related to changes in chemical bonding upon electronic excitation, as described in Section 2. The relation E Stokes = (2S À 1) ho is used in many reports, 1,[12][13][14][15][16][17][18][19] while other works use the alternative relation E Stokes = 2S ho (ref. [20][21][22][23][24], or are ambiguous about it.…”

Section: Introductionmentioning

confidence: 99%

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Jong

Seijo

Meijerink

et al. 2015

Phys. Chem. Chem. Phys.

252

235

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Electronic transitions in luminescent molecules or centers in crystals couple to vibrations. This results in broadening of absorption and emission bands, as well as in the occurence of a Stokes shift E Stokes . In principle, one can derive from E Stokes the Huang-Rhys parameter S, which describes the microscopic details of the vibrational coupling and can be related to the equilibrium position offset DQ e between the ground state and excited state. The commonly used textbook relations E Stokes = (2S À 1) ho and E Stokes = 2S ho are only approximately valid. In this paper we investigate how E Stokes is related to S, taking into account the effects of a finite temperature. We show that in different ranges of temperature, different approximate relations between E Stokes and S are appropriate. Moreover, we demonstrate that the difference between the barycenters of absorption and emission bands can be used to determine S in an unambiguous way.The position of the barycenter is, contrary to the Stokes shift, unaffected by temperature.

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Section: Introductionmentioning

confidence: 99%

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Jong

Seijo

Meijerink

et al. 2015

Phys. Chem. Chem. Phys.

252

235

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“…[49][50][51][52][53] An empirical host referred binding energy level scheme was already constructed in 2005, although some radical simplifications were made at that time. This ternary sulfide is well known as a host crystal for efficient lanthanide luminescence.…”

Section: Introductionmentioning

confidence: 99%

Energy level modeling of lanthanide materials: review and uncertainty analysis

Joos

Poelman

Smet

2015

Phys. Chem. Chem. Phys.

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Energy level schemes are an essential tool for the description and interpretation of atomic spectra. During the last 40 years, several empirical methods and relationships were devised for constructing energy level schemes of lanthanide defects in wide band gap solids, culminating in the chemical shift model by Thiel and Dorenbos. This model allows us to calculate the electronic and optical properties of the considered materials. However, an unbiased assessment of the accuracy of the obtained values of the calculated parameters is still lacking to a large extent. In this paper, error margins for calculated electronic and optical properties are deduced. It is found that optical transitions can be predicted within an acceptable error margin, while the description of phenomena involving conduction band states is limited to qualitative interpretation due to the large error margins for physical observables such as thermal quenching temperature, corresponding to standard deviations in the range 0.3-0.5 eV for the relevant energy differences. As an example, the electronic structure of lanthanide doped calcium thiogallate (CaGa2S4) is determined, taking the experimental spectra of CaGa2S4:Ln(Q+) (Ln(Q+) = Ce(3+), Eu(2+), Tm(3+)) as input. Two different approaches to obtain the shape of the zig-zag curves connecting the 4f levels of the different lanthanides are explored and compared.

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“…D is the energy lowering, also called the red shift, and Δ S is the Stokes shift. As the excitation spectrum is not well resolved, the position of the lowest 5d excited level of Eu 2+ ( E abs ) is generally estimated by using the mirror‐image relationship between the emission and the excitation spectra 4. The Stokes shift (Δ S ) can be estimated by taking twice the energy difference between the zero‐phonon line and the energy of the emission maximum 20, 21.…”

Section: Resultsmentioning

confidence: 99%

“…The ternary compounds M II M 2 III (S,Se) 4 doped with rare‐earth ions have been studied for several years and are found to be very attractive for lighting and display applications, such as field emission displays (FEDs), thin‐film electroluminescence (TFEL), and phosphor‐converted light emitting diodes (pc‐LEDs) 1–6. CaGa 2 S 4 :Eu 2+ and Sr 2 Ga 2 S 5 :Eu 2+ greenish‐yellow phosphors show a higher luminescent efficiency (120 and 110%, respectively) than the commercial yttrium aluminum garnet: Ce 3+ phosphor, and they also can be combined with blue LED chips to produce white light 7, 8.…”

Section: Introductionmentioning

confidence: 99%

Luminescence properties of stoichiometric EuM₂S₄ (M = Ga, Al) conversion phosphors for white LED applications

Yang

Moon

et al. 2012

Physica Status Solidi (a)

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EuM2S4 (M = Ga, Al) phosphors were synthesized using the solid‐state reaction method. The structure and photoluminescence (PL) properties of the phosphors were investigated in detail. XRD pattern results indicated that the two phosphors are isostructures to the orthorhombic structure. The PL spectra showed that the EuGa2S4 and EuAl2S4 phosphors can be excited efficiently by UV–visible light from 350 to 480 nm and that they emit intense green and bluish‐green light, with emission bands peaking at 545 and 506 nm, respectively. The fluorescence lifetimes of Eu2+ were calculated to be 0.076 and 0.064 µs for EuGa2S4 and EuAl2S4, respectively. The thermal quenching temperature was 412 K for EuGa2S4. A green LED was fabricated by the combination of a near‐UV InGaN chip and the prepared EuGa2S4 phosphor. The EuGa2S4 phosphor exhibits much better green color purity than EuAl2S4. As a result, EuGa2S4 might be a promising green phosphor candidate for solid‐state lighting LED technology.

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Electron–vibrational interaction in 4f–5d optical transitions in Ba, Ca, Sr thiogallates doped with Eu2+ ions

Cited by 43 publications

References 23 publications

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Energy level modeling of lanthanide materials: review and uncertainty analysis

Luminescence properties of stoichiometric EuM₂S₄ (M = Ga, Al) conversion phosphors for white LED applications

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Electron–vibrational interaction in 4f–5d optical transitions in Ba, Ca, Sr thiogallates doped with Eu2+ ions

Cited by 43 publications

References 23 publications

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Resolving the ambiguity in the relation between Stokes shift and Huang–Rhys parameter

Energy level modeling of lanthanide materials: review and uncertainty analysis

Luminescence properties of stoichiometric EuM2S4 (M = Ga, Al) conversion phosphors for white LED applications

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Product

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Luminescence properties of stoichiometric EuM₂S₄ (M = Ga, Al) conversion phosphors for white LED applications