Electronic structure and optical absorption of the Bi4Ge3O12 and the Bi4Si3O12 scintillators in ultraviolet region: An ab initio study

Lima, A.F.; Souza, S.O.; Lalić, M.V.

doi:10.1063/1.3160291

Cited by 32 publications

(14 citation statements)

References 23 publications

(26 reference statements)

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“…Majority states are the spin-up, and calculated magnetic moment of Cr is +1.58 B . The composition of other bands which originate from the host BGO matrix, unaffected by the Cr presence, is the same as previously reported 14.…”

supporting

confidence: 84%

“…Table I stresses importance of relativistic treatment of the Bi electronic states, a fact that has been proved in previous ab initio studies of pure BGO. 14,20 B. Local structure around the impurity Information about local structures around Cr impurities was accessed via computational relaxation of atomic positions in BGO:Cr crystal.…”

Section: A Defect Formation Energiesmentioning

confidence: 99%

“…In order to comprise these goals, we employed the first-principles density-functional theory ͑DFT͒ based calculations and treated doped BGO crystal with substitutional Cr impurities situated either at the Ge 4+ or at the Bi 3+ site. The calculated properties were compared with ones recently determined for the pure BGO crystal, 13,14 which enabled us to extract the effects caused by Cr presence. Results of atomic relaxations around the impurity showed that the Cr 3+ suffers off-site displacement away from the center of O's octahedron around it, not supporting the Wu and Dong prediction.…”

Section: Introductionmentioning

confidence: 99%

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Structural, electronic, and optical aspects of Cr doping of the Bi4Ge3O12: An ab initio study

Lima

Lalić

2010

Journal of Applied Physics

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Ab initio calculations based on density functional theory have been employed to study energetic, structural, electronic, and optical properties of Cr doped Bi 4 Ge 3 O 12 ͑BGO͒. Two possible accommodations of Cr impurity have been taken into account: at the Ge ͑Cr 4+ ͒ and the Bi ͑Cr 3+ ͒ substitution site. For each accommodation the local structure around the Cr has been determined, and in the Cr 3+ case the Cr off-site displacement was analyzed. The Cr d-states are positioned at the bottom of the conduction band and within the gap in form of two deeplike ͑Cr 4+ ͒ and shallowlike ͑Cr 3+ ͒ bands, exhibiting magnetic moments of +1.58 B and −2.44 B , respectively. The Cr dominated part of absorption spectrum is calculated and analyzed in terms of Cr band arrangement. Comparison with the experimental BGO:Cr absorption spectrum suggests that it consists of both Cr 3+ and Cr 4+ contributions, indicating the Cr simultaneous presence at both substitution sites.

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supporting

confidence: 84%

Section: A Defect Formation Energiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Structural, electronic, and optical aspects of Cr doping of the Bi4Ge3O12: An ab initio study

Lima

Lalić

2010

Journal of Applied Physics

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“…The correlation between ( L ex /L veg ) max and the band gap difference Δ E g basing on E g values is plotted in Figure . Despite the strong LY enhancement in garnets and some halides with Δ E g > 0.9, large positive deviations of LY were observed as well in systems with weak E g changes.…”

Section: Phenomenological Approach To Ly Predictionmentioning

confidence: 99%

Trends in Search for Bright Mixed Scintillators

Sidletskiy

2018

Physica Status Solidi (a)

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The paper addresses the recent progress in study of light yield behavior in scintillators based on solid solutions (mixed crystals), which are among the brightest known scintillators. Following the prior work [O. Sidletskiy et al., Phys. Status Solidi A 2014, 211, 2384, the extended phenomenological analysis of the correlations between light yield behavior and physical properties of mixed crystals (band gaps of the components, ionic radii, and atomic weights of the substitutional atoms) is carried out. The trend to light yield enhancement is notable in systems with the substitution of atoms in two non-equivalent crystallographic sites in the lattice leading to formation of planes and columns enriched with one of the substitutional atoms. This evidences an important role of nanoscale spatial inhomogeneity (domains or clusters) in scintillation process in mixed scintillators. A roadmap of search for new bright scintillators is proposed basing on the established trends.

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“…[1][2][3] For example, bismuth germanate Bi 4 Ge 3 O 12 (BGO) crystal is a famous scintillator and widely used in nuclear medicine, 4 highenergy physics, 5 medical imaging (XCT, PET), 6 geological prospecting and other industries. 7 Bismuth silicate Bi 4 Si 3 O 12 (BSO) crystal has a high density of 6.80 g/cm 3 , a short radiation length of X 0 = 1 15 cm, a light yield as large as 20% of BGO, a faster decay time of 100 ns, a high hardness of 5 Mohs, absence of hygroscopicity and cleavage.…”

Section: Introductionmentioning

confidence: 99%

Development of Doped Bi4Si3O12 Crystals for Scintillation, Laser and LED Applications

Jia-Yue¹,

Bobo²,

Zhang³

2015

mater focus

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Bismuth silicate Bi 4 Si 3 O 12 (BSO) crystal is a fast scintillator which has potential applications in high energy physics, nuclear physics, computed tomography and dosimetry. Compared with widely used Bi 4 Ge 3 O 12 (BGO) crystal, BSO has some better scintillation properties such as a faster decay time, greater radiation hardness and a lower raw material cost, so it is considered to be the substitute for an alternative to BGO crystals. However, two main problems hindered its practical applications: (1) it is difficult to grow large size and high quality crystals due to its compositional segregation; (2) BSO has a relatively low light yield. Recently, large size BSO crystals have been grown by the modified vertical Bridgman method in Shanghai Institute of Technology. The scintillation properties of rare earth doped BSO crystals have been investigated and BSO crystal doped with small amount Dy 2 O 3 increases its light yield remarkably. Furthermore, some experimental results revealed the potential applications of Re-doped BSO crystals in laser and LED fields. In this review, the growth process, scintillation properties and luminescent mechanism of Re or Ge doped BSO crystals were introduced. The spectroscopic properties and energy transfer of Re-doped BSO crystals were discussed based on its applications in laser and LED. As a result, doped BSO crystal is a novel multi-functional material for scintillation, laser and LED applications.

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Electronic structure and optical absorption of the Bi4Ge3O12 and the Bi4Si3O12 scintillators in ultraviolet region: An ab initio study

Cited by 32 publications

References 23 publications

Structural, electronic, and optical aspects of Cr doping of the Bi4Ge3O12: An ab initio study

Structural, electronic, and optical aspects of Cr doping of the Bi4Ge3O12: An ab initio study

Trends in Search for Bright Mixed Scintillators

Development of Doped Bi<SUB>4</SUB>Si<SUB>3</SUB>O<SUB>12</SUB> Crystals for Scintillation, Laser and LED Applications

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