Temperature dependence of the EFG at Cd‐doped Lu
 2
 O
 3
 : How
 ab initio
 calculations can complement PAC experiments

Errico, L. A.; Rentería, M.; Bibiloni, A. G.; Darriba, G. N.

doi:10.1002/pssc.200461788

Cited by 11 publications

(9 citation statements)

References 11 publications

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“…After structural relaxations, with the electronic structure of the doped systems included in a self-consistent full-potential approach, both methods have provided the same electronic and equilibrium structure, and predictions for the EFG tensor. Cd introduces structural distortions in the host lattice, following a general trend already observed in other 111 Cd-doped metal oxides, 17,18,[25][26][27] i.e., with the Cd atom trying to reconstruct the bond length that it has in its most stable oxide, CdO.…”

Section: Discussionmentioning

confidence: 81%

“…These theoretical EFG tensors are then compared to available experimental TDPAC results. 30,31 Although the EFG has already been proved to be a powerful tool to identify impurity sites in metal oxides, 17,19,25,27,28 to our knowledge, a deep study of the Cd localization in Al 2 O 3 through a direct confrontation between measurements and reliable ab initio predictions has not been reported yet. Nevertheless, the situation faced in the present study is complicated by the fact that, in confronting experiments and ab initio EFG results, two possibly equivalent scenarios are found, and to further unravel this issue, we performed energetic studies.…”

Section: Introductionmentioning

confidence: 99%

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Site localization of Cd impurities in sapphire

et al. 2012

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By combining first-principles electronic structure calculations and existing time-differential γ -γ perturbedangular-correlation experiments we studied the site localization, the local environment, and the electronic structure of Cd impurities in sapphire (α-Al 2 O 3 ) single crystals in different charged states. The ab initio calculations were performed with the full-potential augmented plane wave plus local orbitals method and the projector augmented wave method. Comparing the calculated electric-field-gradient tensor at the Cd nuclei in the α-Al 2 O 3 host lattice and the corresponding available experimental values, we have seen that it is equally possible for Cd to replace an Al atom (in a negative charge state) or to be placed in an interstitial site (in a neutral charge state). To finally address the issue of the Cd impurity localization, we performed formation energy calculations. These results have shown that Cd placed in the substitutional Al site, in the negatively charged state, is the most probable configuration.

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Section: Discussionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Site localization of Cd impurities in sapphire

et al. 2012

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“…The overall band structures obtained here are consistent with previous theoretical results obtained in other isomorphous Ln sesquioxides. 23,40 The different approximations used for the exchange and correlation energy predict a similar direct (minimum) band gap at the point for each system, which is ∼4.0 eV for Sc 2 O 3 and 1.2 eV for In 2 O 3 (Fig. 3).…”

Section: A Pure Ln 2 Omentioning

confidence: 81%

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

et al. 2013

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The electronic, structural, and hyperfine properties of pure and Cd-doped lanthanide (Ln) sesquioxides with the cubic bixbyite structure (Ln 2 O 3 , Ln ranging from La to Lu) have been studied using the full-potential augmented plane wave plus local orbital (APW + lo) method within the local spin density approximation (LSDA) and the Coulomb-corrected LSDA + U . In the case of the pure systems, our calculations show that LSDA + U gives a better representation of the band structure compared to LSDA. The predicted equilibrium structures and the electric field gradient (EFG) tensor at Ln sites were calculated and compared with those obtained by means of hyperfine techniques and with theoretical results obtained in In 2 O 3 , Sc 2 O 3 , and Lu 2 O 3 reported in the literature. The origin of the EFG at Ln sites and the role played by the 4f electrons on this quantity are discussed. In the case of the Cd-doped systems, the APW + lo method (also within LSDA and LSDA + U ) was applied to treat the electronic structure of the doped system. The role of the Ln 4f electrons on the EFG at Cd impurity sites, and other variables like structural distortions induced by the Cd impurity, were investigated in detail and are discussed and compared with available experimental results. An excellent agreement between the experimental and calculated EFGs was found for all Cd-doped systems.

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“…Winkler and Gerdau developed a description of PAC spectra for dynamic hyperfine interactions based on stochastic processes [61]: the environment of a probe nucleus may instantaneously change between different environmental states. This theory has been applied to fluctuating EFG's originating from the trapping and release of charges [17][18][19]62]. In these cases the charge carriers were in thermal equilibrium with their environment.…”

Section: Defect and Diffusion Forum Vol 311mentioning

confidence: 99%

Impurity Centers in Oxides Investigated by γ-γ Perturbed Angular Correlation Spectroscopy and Ab Initio Calculations

Pasquevich

Rentería

2011

DDF

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Abstract. In this chapter Perturbed Angular Correlation (PAC) experiments on binary oxides are described. These experiments provide local-scale fingerprints about the formation, identification, and lattice environment of defect complexes at the PAC probe site. The potential of the PAC observations in conjunction with ab initio calculations is shown. Measurements of the electric-field gradient at impurity sites using 111 Cd and 181 Ta probes are reviewed. Special attention is paid to oxides with the bixbyite structure. The case of In 2 O 3 is particularly analyzed. Results obtained with HfO 2 , in form of coarse grain or nano particles, are described. The potential results that can be obtained from Density Functional Theory ab initio calculations in doped systems are shown describing the main results observed in many impurity-host systems.

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Temperature dependence of the EFG at Cd‐doped Lu ₂ O ₃ : How ab initio calculations can complement PAC experiments

Cited by 11 publications

References 11 publications

Site localization of Cd impurities in sapphire

Site localization of Cd impurities in sapphire

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

Impurity Centers in Oxides Investigated by γ-γ Perturbed Angular Correlation Spectroscopy and <i>Ab Initio</i> Calculations

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Temperature dependence of the EFG at Cd‐doped Lu 2 O 3 : How ab initio calculations can complement PAC experiments

Cited by 11 publications

References 11 publications

Site localization of Cd impurities in sapphire

Site localization of Cd impurities in sapphire

AbinitioLSDA and LSDA+Ustudy of pure and Cd-doped cubic lanthanide sesquioxides

Impurity Centers in Oxides Investigated by γ-γ Perturbed Angular Correlation Spectroscopy and <i>Ab Initio</i> Calculations

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Temperature dependence of the EFG at Cd‐doped Lu ₂ O ₃ : How ab initio calculations can complement PAC experiments