Aurivillius Bi4Ti3O12 ceramics co-dopped with Fe/Nb,

REBOLA, ALEJANDRO; LAVADO, CRISTIAN; STACHIOTTI, MARCELO

Simposio; XXIII Latin American Symposium on Solid State Physics; 2018

Bi4Ti3-x(Nb0.5Fe0.5)xO12 (BTFNx) ceramics with 0 ≤ x ≤ 2 were synthesized to evaluate the effect of Fe3+/Nb5+ co-substitution into the B-site of Bi4Ti3O12 (BIT). We show that the XRD pattern for the compounds with x ≤ 1 is the characteristic one of a layered perovskite structure belonging to the n=3 member of the Aurivillius family. Impurity peaks assigned to a pyrochlore phase were detected at higher concentrations. Ramanmeasurements corroborated that Fe3+and Nb5+ ions were incorporated into the Ti sites of the Aurivillius structure. Frequency dependent dielectric studies at room-temperature displayed a reduction of both dielectric constant and loss tangent with substitution, whilethe electric-field- induced polarization switching behavior indicated a ferroelectric character. It was observed that the ferroelectric transition temperature decreased with increasing Fe/Nb content. Magnetic measurements indicated no evidence of ferromagnetic ordering, but antiferromagnetic spin correlations between Fe3+ ions. First principles calculations performed on Bi4TiNbFe 0O12 predict an electric spontaneouspolarization of ~30uC/cm 2 and confirm the antiferromagnetic ground state of the BTFN system, for which we obtain a nearest-neighbor super-exchange coupling J=7meV. We assessed different B sites configurations and found a preference for Ti3+ ions to be located at inner B sites