Experimental and ab initio study of 181Ta-doped Sc2O3 semiconductor

E. MUÑOZ, D. RICHARD, A. G. BIBILONI, L. A. ERRICO, P. D. EVERSHEIM Y M. RENTERÍA.

Ciudad Autónoma de Buenos Aires, Argentina

Workshop; Workshop "At the Frontiers of Condensed Matter physics IV"; 2008

Comite internacional

Trabajo presentado en forma de poster durante la reunionRecently, experimental and ab initio studies ofhyperne interactions in solids has enabled to reinterpreterroneous assignments in previously reportedPAC experiments in diluted semiconductor oxides.In particular, ab initio calculations in Ta-dopedIn2O3 semiconductor were used to reinterpret thehyperne parameters dependence with the bixbyitelattice constant in these sesquioxides and a correctdetermination of the experimental electric-eld gradients(EFGs) at defect free cation sites. The systemsthat need a revision of the hyperne parameters areIn2O3 and Sc2O3 among others, due to their smallerlattice parameters. In this work, we present ab initiocalculations and results of new Perturbed AngularCorrelations experiments on the 181Ta-doped Sc2O3semiconductor. The theoretical calulations were performedat Ta impurities located at both cationic sitesC and D of the Sc2O3 structure, using the AugmentedPlane Waves + Local Orbital (APW+LO) methodin the framework of the Density Functional Theory(DFT), with an impurity dilution of 1:48. We studied the EFGs for dierent charge states of the impurities(neutral cell, and removing 1 and 2 electrons). ThePAC experiments were performed at La Plata withthe PACAr spectrometer [1] in Sc2O3 polycrystallinepellets implanted with 181Hf (! 181Ta) ions at theISKP ion accelerator. The samples were thermallyannealed in air to eliminate the radiation dammage(at 673 K, 1173 K, 1273 K, and 1373 K, during1h). The temperature dependence of the EFGs wasdetermined at defect free cation sites C and D in therange 373 K-1173 K. The APW+LO results werefound to be in excellent agreement with the newexperimental values. Finally, the dependence of thehyperne parameters with the lattice parameter ofthe bixbyite oxides was revisited.[1] M. Rentería et al., Hyperne Interactions (2008), inpress (DOI 10.1007/s10751-008-9706-9).1 - 31 { Perturbed Angular