Incorporation of lanthanide ions in lead titanate

Lanthanide ion doping of lead titanate was investigated using structural and differential scanning calorimetry measurements. Dense ceramics samples were prepared with starting compositions, Pb(1-3x/2)Ln (x) TiO3, assuming A-site substitution of Ln = La, Nd, Sm, Eu, Gd and Dy, at 2 and 8 at.%. Doping with La3+ reduced the tetragonality and cell volume. A systematic recovery in these values was observed for the smaller Ln(3+) ions, suggesting the onset of partial substitution of the Ln ions at the B-site. The ferroelectric-paraelectric transition temperatures also recovered, consistent with an increased probability of B-site occupation with decreasing ion size. Evidence for site occupancy obtained from the presence cation vacancies is also discussed.