Local structure of the B-site in BNT-xBT investigated by ^47,49Ti NMR: Effect of barium content

Towards a deeper understanding of the local structure of the B-site in (100-x)(Bi_1/2Na_1/2)TiO₃-xBaTiO₃ (BNT-xBT) with 0 ≤ x ≤ 15, solid-state nuclear magnetic resonance (NMR) spectra of the titanium isotopes ⁴⁷Ti and ⁴⁹Ti were investigated. The ^47,49Ti NMR spectra of BNT-xBT indicate a disordered local structure for the B-site of these perovskites. The line-shape of the titanium NMR spectra of BNT-xBT samples is found to be independent on the barium content. This fact implies that the local structure of the B-site remains invariant with respect to the structural changes that result from the chemical modification with barium. The analysis of ^47,49Ti NMR spectra supports the hypothesis that the main structural changes across the morphotropic phase boundary in these solid-solutions are constrained to the A-site and are related to the tilting of rigid oxygen octahedra.