First-principles density functional theory calculations were used to investigate the

ground-state structures of PbTiO3 solid solutions containing Ni, Pd and Pt.

Anomalous effective charges were reported; including the first report of a negative

Born effective charges for nominal +2 cations. It was predicted that these proposed

materials would display a decreased band-gap, when compared to PbTiO3, while

maintaining or enhancing polarization.

New Highly Polar Semiconductor Ferroelectrics Through d8 Cation-O Vacancy

Substitution into PbTiO3: a Theoretical Study. J.W.Bennett, I.Grinberg,

A.M.Rappe: Journal of the American Chemical Society, 2008, 130[51], 17409-12