First-principle study of local and electronic structures of yttrium-doped $$\hbox {Ba}(\hbox {Zr}_x \hbox {Ti}_{1-x}) \hbox {O}_3$$ Ba ( Zr x Ti 1 - x ) O 3

Abstract

Yttrium substitution in $$\hbox {Ba}(\hbox {Zr}_x \hbox {Ti}_{1-x})\hbox {O}_3$$ (BZT) solid solutions has been found to be an effective way to induce relaxor behavior and improve their dielectric and ferroelectric performances. However, the underlying mechanism of such enhancement is not yet well understood. Here we employ density functional theory with the generalized gradient approximation to investigate the effect of yttrium on the structural and electronic properties of BZT for x = 0.125, 0.250, and 0.375. The results will be discussed in terms of yttrium site preference, atomic pair distribution functions (PDFs), cation off-centering and electronic density of states. It was found that yttrium incorporation could occur in either A- or B-site with corresponding defect vacancies and that the effect of the sites of impurities is only to cause small changes in formation energies. The calculated PDFs and cation off-centering indicate that yttrium ions actively induce lattice distortion and increase structural disorder. This implies that the addition of yttrium in BZT suppresses the ferroelectric instabilities and may help to explain the transition from ferroelectric to relaxor state of such materials.