Segregation of Ti⁴⁺ and Ce⁴⁺ impurity-cations at the grain boundaries of CeO₂-TiO₂-ZrO₂ ceramics for overcoming strength deterioration after grain coarsening

The deterioration of the mechanical properties of ZrO₂-based ceramics after grain coarsening has become a key challenge hindering their wide application as advanced structural materials. The present work reports that novel TiO₂-CeO₂-ZrO₂ ternary ceramics with spontaneous segregation of Ti⁴⁺ impurity-cations at grain boundaries could be successfully realized by TiO₂ composition modulation in 12CeO₂-ZrO₂ matrix. Experimental results reveal that compared with the 12CeO₂-ZrO₂ binary ceramics, the 10TiO₂-12CeO₂-ZrO₂ ternary ceramic retains high compressive strength (1853 ± 35 MPa) and flexural strength (359 ± 9 MPa) even after grain coarsening. This remarkable performance retention is primarily attributed to three key factors: a high relative density of 99.09 %, a t-ZrO₂ phase with 100 % volume fraction, and the synergistic segregation of Ti⁴⁺ and Ce⁴⁺ at grain boundaries. Especially, the grain boundary segregation enhances grain boundary strength and induces martensitic transformation near the grain boundary to form a m-ZrO₂ phase with long-period stacking order (LPSO) structure. These findings will provide a new strategy for the preparation of coarse-grained ZrO₂-based ceramics with unique properties.