Improvement of LaBr3:5%Ce scintillation properties by Li+, Na+, Mg2+, Ca2+, Sr2+, and Ba2+ co-doping

Alekhin, Mikhail S.; Biner, Daniel; Krämer, Karl; Dorenbos, P.

doi:10.1063/1.4810848

Cited by 59 publications

(23 citation statements)

References 22 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The highest light yield ( LY ) scintillating crystals are currently found among oxides ((Lu,Y) 2 SiO 5 :Ce,Ca LY = 32,000 ph/MeV [8], Gd 3 (Al,Ga) 5 O 12 :Ce, LY = 58,000 ph/MeV [9], (Gd,La) 2 Si 2 O 7 :Ce. LY = 41,000 ph/MeV [10]), chlorides (LaCl 3 :Ce, LY = 49,000 ph/MeV [11]), bromides (LaBr 3 :Ce, LY = 77,000 ph/MeV [12]) and iodides (SrI 2 :Eu, LY > 80,000 ph/MeV [13,14]. Theoretically, the maximum achievable photon yield LY , expressed as the number of photons emitted when 1 MeV of γ-ray energy is absorbed (ph/MeV), is proportional to the number of electron-hole pairs created by the ionizing radiation.…”

Section: Introductionmentioning

confidence: 99%

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

et al. 2015

View full text Add to dashboard Cite

Eu-doped ternary sulfides of general formula ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y) are presented as a novel interesting material family which may find usage as X-ray phosphors or solid state white light emitting diode (LED) lighting. Samples were synthesized in the form of transparent crystalline hexagonal platelets by chemical reaction under the flow of hydrogen sulfide. Their physical properties were investigated by means of X-ray diffraction, time-resolved photoluminescence spectroscopy, electron paramagnetic resonance, and X-ray excited fluorescence. Corresponding characteristics, including absorption, radioluminescence, photoluminescence excitation and emission spectra, and decay kinetics curves, were measured and evaluated in a broad temperature range (8–800 K). Calculations including quantum local crystal field potential and spin-Hamiltonian for a paramagnetic particle in D3d local symmetry and phenomenological model dealing with excited state dynamics were performed to explain the experimentally observed features. Based on the results, an energy diagram of lanthanide energy levels in KLuS2 is proposed. Color model xy-coordinates are used to compare effects of dopants on the resulting spectrum. The application potential of the mentioned compounds in the field of white LED solid state lighting or X-ray phosphors is thoroughly discussed.

show abstract

Section: Introductionmentioning

confidence: 99%

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Similar effects were observed with Ca and Ba whereas doping with Li, Na, or Mg does not improve the scintillation response and can even be detrimental. 35 To resolve these observations, the investigation of dopant related defects was extended to cover both the alkaline (Li, Na, K, Rb, Cs) and alkaline earth (Be, Mg, Ca, Sr, Ba) groups. It comprised the same configurations and charge states that were already described in Sect.…”

Section: E Solubility Analysismentioning

confidence: 99%

First-principles study of codoping in lanthanum bromide

et al. 2015

View full text Add to dashboard Cite

Co-doping of Ce-doped LaBr3 with Ba, Ca, or Sr improves the energy resolution that can be achieved by radiation detectors based on these materials. Here, we present a mechanism that rationalizes of this enhancement that on the basis of first principles electronic structure calculations and point defect thermodynamics. It is shown that incorporation of Sr creates neutral VBr − SrLa complexes that can temporarily trap electrons. As a result, Auger quenching of free carriers is reduced, allowing for a more linear, albeit slower, scintillation light yield response. Experimental Stokes shifts can be related to different CeLa − SrLa − VBr triple complex configurations. Co-doping with other alkaline as well as alkaline earth metals is considered as well. Alkaline elements are found to have extremely small solubilities on the order of 0.1 ppm and below at 1000 K. Among the alkaline earth metals the lighter dopant atoms prefer interstitial-like positions and create strong scattering centers, which has a detrimental impact on carrier mobilities. Only the heavier alkaline earth elements (Ca, Sr, Ba) combine matching ionic radii with sufficiently high solubilities. This provides a rationale for the experimental finding that improved scintillator performance is exclusively achieved using Sr, Ca, or Ba. The present mechanism demonstrates that co-doping of wide gap materials can provide an efficient means for managing charge carrier populations under out-of-equilibrium conditions. In the present case dopants are introduced that manipulate not only the concentrations but the electronic properties of intrinsic defects without introducing additional gap levels. This leads to the availability of shallow electron traps that can temporarily localize charge carriers, effectively deactivating carrier-carrier recombination channels. The principles of this mechanism are therefore not specific to the material considered here but can be adapted for controlling charge carrier populations and recombination in other wide gap materials.

show abstract

“…17 A more comprehensive investigation, including both the alkaline as well as earth-alkaline series, revealed that better performance is only achievable when using the heavier elements of the latter series (Sr, Ca, and Ba). 18,19 Several possible mechanisms were tentatively proposed to rationalize these observations: 20 (i) reduction of the nonradiative recombination rate, (ii) an increase of the so-called escape rate of the carriers from the quenching region, or (iii) an increase in the trapping rate of Ce 3þ . Here, we address this question via first principles calculations of thermodynamic and electronic properties of intrinsic and extrinsic defects as well as their complexes in Ce and Sr-doped LaBr 3 .…”

mentioning

confidence: 99%

Origin of resolution enhancement by co-doping of scintillators: Insight from electronic structure calculations

Åberg

Sadigh

Schleife

et al. 2014

Applied Physics Letters

View full text Add to dashboard Cite

Citation for the published paper: Aberg, D. ; Sadigh, B. ; Schleife, A. (2014) "Origin of resolution enhancement by co-doping of scintillators: Insight from electronic structure calculations". Applied Physics Letters, vol. 104(21), http://dx.It was recently shown that the energy resolution of Ce-doped LaBr 3 scintillator radiation detectors can be crucially improved by co-doping with Sr, Ca, or Ba. Here, we outline a mechanism for this enhancement on the basis of electronic structure calculations. We show that (i) Br vacancies are the primary electron traps during the initial stage of thermalization of hot carriers, prior to hole capture by Ce dopants; (ii) isolated Br vacancies are associated with deep levels; (iii) Sr doping increases the Br vacancy concentration by several orders of magnitude; (iv) Sr La binds to V Br resulting in a stable neutral complex; and (v) association with Sr causes the deep vacancy level to move toward the conduction band edge. The latter is essential for reducing the effective carrier density available for Auger quenching during thermalization of hot carriers. Subsequent de-trapping of electrons from Sr La -V Br complexes can activate Ce dopants that have previously captured a hole leading to luminescence. This mechanism implies an overall reduction of Auger quenching of free carriers, which is expected to improve the linearity of the photon light yield with respect to the energy of incident electron or photon. V C 2014 AIP Publishing LLC.

show abstract

Improvement of LaBr3:5%Ce scintillation properties by Li+, Na+, Mg2+, Ca2+, Sr2+, and Ba2+ co-doping

Cited by 59 publications

References 22 publications

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

Optical, Structural and Paramagnetic Properties of Eu-Doped Ternary Sulfides ALnS2 (A = Na, K, Rb; Ln = La, Gd, Lu, Y)

First-principles study of codoping in lanthanum bromide

Origin of resolution enhancement by co-doping of scintillators: Insight from electronic structure calculations

Contact Info

Product

Resources

About