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Habenicht,; Lupaşcu,; Neubauer, Franz; Uhrmacher,; Lieb,; ISOLDE‐Collaboration, the

doi:10.1023/a:1017049523366

Cited by 16 publications

(13 citation statements)

References 8 publications

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“…Some fingerprints of this thermal equilibrium situation are the near constancy of the EFG, its high monochromaticity, and reversibility as a function of temperature in a very wide temperature range. Hence, in the γ -γ TDPAC experiments of Habenicht et al 30 and Penner et al 31 All these results strongly suggest that in the three experiments the 111 Cd probes are at the substitutional Al site. This fact, along with the agreement between the experimentally determined EFG absolute value and that predicted by the ab initio calculations show that the 111 Cd impurity is at the substitutional site and is already ionized at 4 K.…”

Section: -7mentioning

confidence: 77%

“…On the other hand, most important here is the fact that the predicted EFG at the interstitial Cd site in the (Al 2 O 3 :Cd i ) 0 neutral system is in excellent agreement with the absolute EFG value obtained in the TDPAC experiments. 30,31 This theoretical scenario would imply that the observed interstitial defect center would not be ionized, at least, in the wide 4-973 K temperature range. Fig.…”

Section: Interstitial CDmentioning

confidence: 99%

“…30,31 The sign of a V ij component of the EFG tensor tells us if the electric-field component in the i direction decreases or increases along the j direction at the probe site. This sign can only be determined for the probes used in Refs.…”

Section: -7mentioning

confidence: 99%

“…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: -7mentioning

confidence: 77%

Section: Interstitial CDmentioning

confidence: 99%

Section: -7mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Site localization of Cd impurities in sapphire

et al. 2012

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“…These values for ν Q are slightly higher than reported in the literature (see refs. [2,6,7]). Over all samples, the temperature dependence of ν Q can be described by the linear relation (1).…”

Section: Resultsmentioning

confidence: 99%

Temperature dependence of the hyperfine fields of 111In in sapphire (Al2O3) single crystals

et al. 2010

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The decay of 111 In to 111 Cd via electron capture, accompanied by Auger electrons, leaves the outermost atomic shells of the cadmium in a highly ionized state. The recovery of the electron shells depends strongly on the electronic environment of the probe nucleus. In order to study this effect, sapphire single crystals were ion implanted with 111 In at the Bonner Isotopenseparator. After annealing, the samples were measured at temperatures up to 900 K. To study the recombination characteristics and the influence of acceptor and donor levels, the samples were additionally doped with various concentrations of Si, Cr, Mg or P.

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Electric‐field gradient characterization at ¹⁸¹Ta impurities in sapphire single crystals

Rentería

Darriba

Errico

et al. 2005

Physica Status Solidi (b)

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We report Perturbed-Angular-Correlation (PAC) experiments on corundum Al 2 O 3 single crystals implanted with 181 Hf/ 181 Ta ions at the ISKP at Bonn and measured at La Plata with high efficiency and timeresolution. The magnitude, asymmetry, and orientation (with respect to the crystalline axes) of the electric-field gradient (EFG) tensor were determined measuring the spin-rotation curves as a function of different orientations of the single crystals relative to the detector system. These results are analyzed in the framework of point-charge model and ab initio Full-Potential Linearized-Augmented Plane Wave calculations, and compared with EFG results coming from PAC experiments with 111 In/ 111Cd impurities. This combined study enables the determination of lattice relaxations induced by the presence of the impurity and the state of charge of a deep impurity donor level in the band gap of the semiconductor.

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Cited by 16 publications

References 8 publications

Site localization of Cd impurities in sapphire

Site localization of Cd impurities in sapphire

Temperature dependence of the hyperfine fields of 111In in sapphire (Al2O3) single crystals

Electric‐field gradient characterization at ¹⁸¹Ta impurities in sapphire single crystals

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Untitled

Cited by 16 publications

References 8 publications

Site localization of Cd impurities in sapphire

Site localization of Cd impurities in sapphire

Temperature dependence of the hyperfine fields of 111In in sapphire (Al2O3) single crystals

Electric‐field gradient characterization at 181Ta impurities in sapphire single crystals

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Electric‐field gradient characterization at ¹⁸¹Ta impurities in sapphire single crystals