Incorporation of Er ³⁺ into BaTiO ₃

The incorporation of Er 3+ into BaTiO 3 ceramics was investigated on samples containing 0.25, 0.5, 1, 2, 8, and 10 at.% of dopant, after sintering at 1350–1550°C in air. For Er 3+ concentrations ≤1 at.%, dense and large‐grained ceramics with low room‐temperature resistivity (10 2 –10 3 Ω·cm) were obtained. The observed properties are largely independent of stoichiometry. Simultaneous substitution of Er 3+ at both cation sites, with higher preference for the Ba site, is proposed. The behavior of heavily doped ceramics depends on stoichiometry. When Ba/Ti < 1, the electrical properties change from slightly semiconducting to insulating as Er concentration increases from 2 to 8 at.%. The ceramics have tetragonal perovskite structure and contain a large amount of Er 2 Ti 2 O 7 pyrochlore phase. On the other hand, when Ba/Ti > 1, the ceramics are insulating, fine‐grained, and single phase. In this case, incorporation of Er 3+ predominantly occurs at the Ti site, with oxygen vacancy compensation. Incorporation is accompanied by a significant reduction of tetragonality and by expansion of the unit cell. The different results indicate that Er 3+ solubility at the Ba site does not exceed 1 at.%, whereas solubility at the Ti site is at least 10 at.%. However, the incorporation of Er 3+ and the resulting properties are also strongly affected by sintering conditions.