Elemental Substitution in Lead Zirconate Titanate: A Combined Density Functional Theory and Experimental Method

Abstract

We systematically and exhaustively investigate the effects of elemental substitutions on the ferroelectric properties of lead zirconate titanate (PZT), using first-principle density functional theory calculations. For donors substitutions, we conclude that two mechanisms contribute to the improved ferroelectric properties in the donor-doped PZT. First, the formation energy of the oxygen vacancies is increased by substituted donors, resulting in a diluted oxygen vacancy concentration in the PZT lattice. Therefore the domain pinning effect and space charge effect are reduced. Second, the electronic states of donors share the conduction band minima with the Ti 3d states, and weaken the electronic suppression effect on the polarization in PZT. For acceptor substitutions, the mechanisms dominating the substitution effects on the improved ferroelectric properties are related to the defect structures. Our calculations reveal that the acceptor-oxygen-vacancy-acceptor cluster structure either along z direction or in xy plane is energetically preferred for most acceptors substituted PZT. This cluster configuration greatly reduces the oxygen vacancy mobility, therefore diminishing the domain pinning effects and space charge effects.