Exciton emission in BaFBr and BaFCl crystals

Раджабов, Е. А.; Egranov, A. V.

doi:10.1088/0953-8984/6/29/006

Cited by 15 publications

(17 citation statements)

References 14 publications

(9 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Two kinds of luminescence bands have been found to appear at 4.52 eV and 3.44 eV. The temperature dependence of these bands is very similar to that of the 5.10 eV and 4.25 eV intrinsic bands in BaFBr [7][8][9]. That is to say, the 3.44 eV band appears anti-correlatively with quenching of the 4.52 eV band dominant at low temperatures, when the sample temperature is raised (Fig.…”

Section: Discussionsupporting

confidence: 58%

“…In BaFBr, a broad luminescence band with a small Stokesshift energy was observed at 5.10 eV at low temperatures below 100 K. This band has been attributed to the intrinsic luminescence from the 'on-center' type of STE which consists most likely of the out-of-plane type of a Br 2 -center and a bound electron [6][7][8][9]. Another STE luminescence band was also found to appear at 4.25 eV, when the 5.10 eV band thermally quenched above 60 K. It has been suggested that the 4.25 eV band arises from the STE being situated in a 'weakly off-center' configuration [7][8][9]. The possibility of off-center relaxation of STEs has been theoLuminescence from BaFI and BaFBr 1-x I x crystals has been investigated using vacuum ultraviolet photons from synchrotron radiation in the temperature range of 10 -300 K. In BaFI, two kinds of luminescence bands are observed under band-toband excitation: one is the 4.52 eV band appearing at low temperatures, and the other is the 3.44 eV band appearing as the 4.52 eV band weakens with increasing temperature.…”

mentioning

confidence: 98%

See 1 more Smart Citation

Luminescence from self‐trapped excitons in BaFI and BaFBr_1–xI_x crystals

Ohnishi

Kan'no

2008

Physica Status Solidi (b)

View full text Add to dashboard Cite

Luminescence from BaFI and BaFBr1–x Ix crystals has been investigated using vacuum ultraviolet photons from synchrotron radiation in the temperature range of 10–300 K. In BaFI, two kinds of luminescence bands are observed under band‐to‐band excitation: one is the 4.52 eV band appearing at low temperatures, and the other is the 3.44 eV band appearing as the 4.52 eV band weakens with increasing temperature. From the excitation spectra, the 4.52 eV band is attributed to the radiative decay of a self‐trapped exciton (STE), and the 3.44 eV band to the extrinsic luminescence coming from an STE trapped by an I– vacancy. The change of luminescence spectra studied in BaFBr1–x Ix suggests that the STE configuration of on‐center type is responsible for the 4.52 eV intrinsic band, and the off‐center instability hardly occurs in BaFI. The temperature dependence of the 4.52 eV and 3.44 eV band intensities is well explained by assuming an STE relaxation mechanism whereby the STE relaxes through phonon‐assisted tunneling and hopping diffusion processes at high temperatures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

Section: Discussionsupporting

confidence: 58%

mentioning

confidence: 98%

Luminescence from self‐trapped excitons in BaFI and BaFBr_1–xI_x crystals

Ohnishi

Kan'no

2008

Physica Status Solidi (b)

View full text Add to dashboard Cite

show abstract

“…Radzhabov pointed out that STE in barium dihalides has the configuration similar to the excitons in alkali-earth fluorides. 31 In SrI 2 crystal having close band gap energy the alike emission was also ascribed to self-trapped exciton emission. 3,4 The STE luminescence quenching with Eu 2+ concentration is due to the exciton emission and 4f-5d Eu 2+ absorption spectra overlapping.…”

Section: Exciton Emission and Band Gapmentioning

confidence: 93%

Optical and structural properties of Eu2+ doped BaBrI and BaClI crystals

Shendrik

Shalaev

Myasnikova

et al. 2017

Journal of Luminescence

View full text Add to dashboard Cite

The work is necessitated by search for new materials to detect ionizing radiation.The rare-earth ions doped with ternary alkali earth-halide systems are promising scintillators showing high efficiency and energy resolution. Some aspects of crystal growth and data on the structural and luminescence properties of BaBrI and BaClI doped with low concentrations of Eu 2+ ions are reported. The crystals are grown by the vertical Bridgman method in sealed quartz ampoule. New crystallography data for BaClI single crystal obtained by single crystal X-ray diffraction method are presented in this paper. Emission, excitation and optical absorption spectra as well as luminescence decay kinetics are studied under excitation by X-ray, vacuum ultraviolet and ultraviolet radiation. The energies of the first 4f-5d transition in Eu 2+ and band gap of the crystals have been obtained. We have calculated the electronic band structure of the crystals using density functional theory as implemented in the Ab Initio. Calculated band gap energies are in accord with the experimental estimates. The energy of gaps between the occupied Eu 2+ 4f level and the valence band top are predicted. In addition, positions of lanthanide energy levels in relation to valence band have been constructed using the chemical shift model.Recently the research focus is shifted to the study of mixed halide compounds due to their superior light yield . 6 In a number of barium dihalides BaFI-BaClI-BaBrI-BaBrCl, the scintillation properties have been studied for Eu-doped BaFI, BaBrCl and BaBrI. 7-11 Despite their excellent properties, experimental data on optical absorption and excitation spectra in spectral region of 4f-5d and band to band transitions are scarce because single-crystals doped with high concentrations of Eu 2+ ions (more than 5 mol. %) were used. When measuring high concentration doped samples, the inner filter effects can be observed. These include reabsorption and non uniform excitation throughout the sample. These effects dramatically change the shape of excitation spectrum. Therefore, estimation of the lowest energy of 4f-5d transitions in Eu-doped BaBrI given in 8,10 is not correct. Furthermore, the experimental determination of band gap in these crystals is not possible due to high absorption related to allowed 4f 6 5d 1 → 4f 7 transitions in Eu 2+ ions. At this moment, the energy of band gap of the mixed halide compounds is based on theoretical estimates.We investigate luminescence, electrical and structural properties of undoped BaBrI, BaBrI-0.05 mol.% Eu 2+ and BaClI-0.1 mol.% Eu 2+ crystals. Absorption, excitation and emission spectra, photoluminescence decay time constants, dielectric properties and pulsed height spectra are presented. The vacuum referred binding (VRBE) energy diagram is constructed in conformity with density functional study. It displays the electron binding energy in the ground and excited state levels of all divalent and trivalent lanthanides ions in BaBrI and BaClI crystals. Methodology Growth and Structural Characteriza...

show abstract

“…In the XL spectra the STE ("Self Trapped Exciton") recombination luminescence at 368 nm [10] is not observed which shows how efficient the Eu 2+ activator is in collecting the radiation energy. The STE may still be involved in the thermally activated recombination mechanisms.…”

Section: +mentioning

confidence: 93%

High temperature thermoluminescence of BaFCl:Eu²⁺ X‐ray storage phosphor

Secu

Predoi

2007

Phys. Status Solidi (c)

View full text Add to dashboard Cite

Thermoluminescence (TL) of Eu2+ -doped BaFCl polycrystalline powders X-ray irradiated at room temperature show several TL peaks at 364 K, 408 K, 470 K, 524 K and 646 K. Thermally activated recombination processes responsible for TL have been studied using complementary techniques as TL and its bleaching, diffuse reflectance, X-ray excited luminescence (XL) and photostimulated luminescence (PSL). Experimental results indicate that F(Cl -) centres are the dominant electron trap centres, the Eu 2+ -trapped hole aggregate centres playing the role of recombination centres. The 470 K and 646 K TSL glow peaks are assigned to the recombination inside the triple aggregates (Eu 2+ -hole centre -F(Cl -) centre). The remaining 408 K and 524 K TL peaks are tentatively assigned to recombination between F centres and double aggregates (Eu 2+ -hole centre).

show abstract

Exciton emission in BaFBr and BaFCl crystals

Cited by 15 publications

References 14 publications

Luminescence from self‐trapped excitons in BaFI and BaFBr_1–xI_x crystals

Luminescence from self‐trapped excitons in BaFI and BaFBr_1–xI_x crystals

Optical and structural properties of Eu2+ doped BaBrI and BaClI crystals

High temperature thermoluminescence of BaFCl:Eu²⁺ X‐ray storage phosphor

Contact Info

Product

Resources

About

Exciton emission in BaFBr and BaFCl crystals

Cited by 15 publications

References 14 publications

Luminescence from self‐trapped excitons in BaFI and BaFBr1–xIx crystals

Luminescence from self‐trapped excitons in BaFI and BaFBr1–xIx crystals

Optical and structural properties of Eu2+ doped BaBrI and BaClI crystals

High temperature thermoluminescence of BaFCl:Eu2+ X‐ray storage phosphor

Contact Info

Product

Resources

About

Luminescence from self‐trapped excitons in BaFI and BaFBr_1–xI_x crystals

Luminescence from self‐trapped excitons in BaFI and BaFBr_1–xI_x crystals

High temperature thermoluminescence of BaFCl:Eu²⁺ X‐ray storage phosphor