Origin of ferroelectricity in perovskite oxides

FERROELECTRIC materials are characterized by a switchable macroscopic polarization

Ronald E. Cohen

2003

Scholarcy highlights

  • FERROELECTRIC materials are characterized by a switchable macroscopic polarization
  • The great sensitivity of ferroelectrics to chemistry, defects, electrical boundary conditions and pressure arises from a delicate balance between long-range Coulomb forces and short-range repulsions
  • To model the transition accurately, total-energy techniques are required which incorporate the effects of charge distortion and covalency
  • I report results of electronic-structure calculations on two classic examples of ferroelectric perovskites, BaTiO3 and PbTiO3, and demonstrate that hybridization between the titanium 3d states and the oxygen 2p states is essential for ferroelectricity
  • The different ferroelectric phase behaviour of the two materials is clear: in PbTiO3, the lead and oxygen states hybridize, leading to a large strain that stabilizes the tetragonal phase, whereas in BaTiO3 the interaction between barium and oxygen is completely ionic, favouring a rhombohedral structure

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