Charge distribution model in cubic perovskite-type compounds

• Autores: Alonso, Roberto Emilio; López García, Alberto Raúl
• Año de publicación: 2000
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: Ciencias Exactas; Física; Defects; Electric Field Gardient; Ferroelectrics Materials; Perovskites; Polarized Oxygen Vacancies
• Institución: Universidad Nacional de La Plata

A non-zero electric field gradient tensor, detected by probes that occupy sites with cubic point group symmetry, was observed in many ABO3 perovskite-type compounds. This breakdown of local cubic symmetry is commonly associated with the presence of oxygen vacancies around the probe. This effect in BaTi_xHf_1-xO₃ with x = 0.7, 0.5, 0.3, 0.1, 0.05 and 0.01 is studied in this work. The cell parameters were obtained at laboratory temperature using XRD spectroscopy. The hyperfine parameters were measured at a ¹⁸¹Ta probe in the B site using Perturbed Angular Correlations (PAC) spectroscopy as a function of both temperature and composition. As a common trend, a static asymmetric and distributed quadrupolar interaction, strongly dependent on composition has been observed. The results, together with those corresponding to 1 > x ≥ 0.75, are analyzed using the point-charge model in terms of polarized oxygen vacancies, different covalence of the Ti-O and Hf-O bonds with computational simulation for the lattice positions of cations and oxygen vacancies.
Facultad de Ciencias Exactas