FP-LAPW study of Cd-doped SnO

L. A. ERRICO, A. G. BIBILONI, H. M. PETRILLI Y M. RENTERÍA.

La Plata, Bs As, Argentina

Workshop; 35th anniversary of Hyperfine Interactions at La Plata International Workshop; 2005

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The study of the interaction of the atomic nucleus with extranuclear fields has proven to be quite useful in many contexts. Nuclear resonance and spectroscopic techniques, such as Nuclear-Quadrupole Resonance (NQR), Nuclear Magnetic Resonance (NMR), Mössbauer spectroscopy (MS), and Time-Differential Perturbed-Angular Correlations (PAC), have been extensively applied to study materials from the point of view of solid-state physics and chemistry in order to elucidate the microscopic environment and the nature of chemical bonding of constituent or impurity atoms (probes) in solids in a large variety of compounds. Besides MS, PAC is probably the most common hyperfine interaction method using radioactive nuclei [1]. By means of this technique, it is possible to measure, the electric-field gradient (EFG) tensor at a precise lattice site. All the information that the EFG tensor can provide about the system under study could be obtained by confrontation of the experiment with an accurate prediction of the EFG, such as ab initio ones. Since the EFG is very sensitive to the anisotropic charge distribution close to the probe-nucleus, for its accurate calculation the entire electronic configuration of the host, perturbed by the presence of the impurity, has to be determined. In this sense, in 1999 we began a systematic study, in the framework of the Density Functional Theroy (DFT), of electronic and structural properties at impurities in oxides, starting with Cd in TiO2 and SnO2 [2-4]. In this work we report a DFT study, using the Full-Potential Linearized-Augmented Plane Waves method, of the EFG at Cd impurities located at the cation site in the semiconductor SnO. In order to simulate the diluted Cd-impurity in the SnO host and to calculate the electronic structure of the system we used the supercell approach, studying the relaxation introduced by the impurity in the lattice. Our prediction for the EFG tensor are compared to experimental PAC results [5], to point-charge model predictions and to results obtained with the PAW method.