Band structure calculations of cerium activated inorganic scintillators

Klintenberg, Mattias; Weber, Marvin J.; Dujardin, Christophe; Eriksson, Olle; Derenzo, Stephen E.

doi:10.1080/10420150108214058

Cited by 5 publications

(3 citation statements)

References 6 publications

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“…Previous calculations for the (Ce 3+ ) * excited state have been performed by removing the Ce 4f states from the basis functions or creating a pseudopotential with Ce 4f states treated as core states. 26,28,33 Our method has the advantage that we can use the same basis set and pseudopotential for both excited state and ground state calculations allowing direct comparison of energies. We then look at the spatial distribution of this excited state to determine if it is localized on the Ce or is a delocalized CB character state.…”

Section: Calculation Detailsmentioning

confidence: 99%

First-principles study of luminescence in Ce-doped inorganic scintillators

et al. 2011

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Luminescence in Ce doped materials corresponds to a transition from an excited state where the lowest Ce 5d level is filled (often called the (Ce 3+ ) * state) to the ground state where a single 4f level is filled. We have performed theoretical calculations based on Density Functional Theory to calculate the ground state band structure of Ce-doped materials as well as the (Ce 3+ ) * excited state. The excited state calculations used a constrained occupancy approach by setting the occupation of the Ce 4f states to zero and allowing the first excited state above them to be filled. These calculations were performed on a set of Ce doped materials that are known from experiment to be scintillators or non-scintillators to relate theoretically calculable parameters to measured scintillator performance. From these studies we developed a set of criteria based on calculated parameters that are necessary characteristics for bright Ce activated scintillators. Applying these criteria to about a hundred new materials we developed a list of candidate materials for new bright Ce activated scintillators. After synthesis in powder form one of these new materials (Ba2YCl7:Ce) was found to be a bright scintillator. This approach, involving first-principles calculations of modest computing requirements was designed as a systematic, high-throughput method to aid in the discovery of new bright scintillator materials by prioritization and down-selection on the large number of potential new materials.

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Section: Calculation Detailsmentioning

confidence: 99%

First-principles study of luminescence in Ce-doped inorganic scintillators

et al. 2011

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“…The possibility of computational modeling to aid scintillator discovery has been the subject of several papers in the past. [10][11][12][13] This is pertinent even more now with the availability of a vast literature of known luminescent materials and powerful computational tools (hardware and algorithms) to study underlying physical phenomena and then employ them for selecting promising candidate materials.…”

Section: Introductionmentioning

confidence: 99%

First-principles studies of Ce-doped RE2M2O7 (RE = Y, La; M = Ti, Zr, Hf): A class of nonscintillators

Chaudhry

Canning

Boutchko

et al. 2011

Journal of Applied Physics

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First-principles study of the electronic structure and optical properties of Ce-doped ZnOLanthanum and yttrium compounds with composition RE 2 M 2 O 7 (RE ¼ Y, La; M ¼ Ti, Zr, Hf) have high density and high Z and can be doped with Ce onto the La and Y sites. This makes these compounds good candidates for Ce-activated scintillator c-ray detectors particularly for the hafnate systems which have a very high density. There is disagreement in the literature concerning La 2 Hf 2 O 7 :Ce as it has been reported to show both bright as well as no Ce-activated luminescence by different experimental groups. We have performed first-principles electronic structure calculations of these compounds doped with Ce using the pseudopotential method based on the generalized gradient approximation in density functional theory. The positions of the Ce 4f states relative to the valence band maximum and the position of the Ce 5d states relative to the conduction band minimum (CBM) of the host material are determined. We find, unlike Ce-activated La and Y compounds where the CBM is typically of La 5d or Y 4d character, that in these systems the CBM is predominately of d character on the Ti, Zr, Hf atoms. For all these compounds, we also find that the Ce 5d state lies above the CBM which would prevent any luminescence from the Ce site.

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“…The simplest approximation is to assume that the density of states and photoemission cross section are roughly uniform over some range of energies, with a sharp rise from zero at the valence band maximum. In fact, this type of density of states is a good approximation to the known density of states in LaF 3 [12,13], a crystal that has many properties similar to LiYF 4 . To fit the observed photoemission, the width of the uniform density of states was allowed to vary while the Gaussian broadening was restricted to values similar to those observed for other photoemission peaks in the spectrum.…”

Section: Locating the 4f 8 Ground State Relative To The Host Bandsmentioning

confidence: 89%