Efecto de las vacancias de Bi en la interfaz entre BaBiO3 e YSZ: un estudio teórico-experimental

WILSON ROMÁN; SOLANGE DI NÁPOLI; PAVAN NUKALA; CYNTHIA QUINTEROS; VALERIA VILDOSOLA; DIEGO RUBÍ

Jornada; Reunión del Instituto de Nanociencia y Nanotecnología; 2020

BaBiO3 has been theoretically proposed as a candidate system to present a 2D electronic gas for a (001) Bi-terminated surface [1]; however, this system has not been synthesized so far. It was shown, instead, for (100)-textured BaBiO3 thin films, from both spectroscopic measurements and ab-initio calculations, the presence of surface electronic effects associated with the absence of apical oxygens in Bi octahedra [2]. This reduces the electronic band-gap and enhances the surface electrical conductivity. In this work, BaBiO3/YSZ bilayers were deposited by laser ablation. YSZ is structurally compatible with the perovskite structure and behaves as an "oxygen scavenger", which in principle could lead to strong deoxygenation of a BaBiO3 layer close to the interface. YSZ was deposited in a wide range of oxygen pressures and the electronic and transport properties of the interfaces were studied. An optimal pressure of 0.1 mbar was determined at which the conductivity of the interface is maximized. From transmission electron microscopy experiments, the presence of a Bi-deficient BaBiO3 layer close to the interface was determined. First-principle calculations were performed to study the effect of Bi vacancies on the material. Our theoretical results indicate that the presence of Bi vacancies leads to the formation of polarons and bipolarons, depending on the number of vacancies. It is proposed that the experimentally observed increase in conductivity at the interface is associated with the diffusion of bipolarons in the Bi-deficient perovskite zone.[1] V. Vildosola et al., Phys. Rev. Lett. 110 (2013) 206805[2] C. Ferreyra et al., AIP Advances 6 (2016) 065310