Liquid-phase sintering of ZrO2-based nanocrystalline glass–ceramics achieved by multielement co-doping

Liquid-phase sintering (LPS) is an effective pathway to assist the densification of ceramics. However, it has seldom been used to densify glass–ceramics. In the present study, a multielement co-doping strategy has been utilized to achieve LPS of a ZrO 2 –SiO 2 nanocrystalline glass–ceramic. Compared with undoped samples densified by solid-state sintering, doping of equimolar Al, Y, and Ca promoted the densification of the glass–ceramic at lower temperatures with a faster densification rate. Ternary doping enhanced coarsening of ZrO 2 nanocrystallites during sintering and annealing. The distribution of dopants was carefully observed with X-ray energy-dispersive spectrometry technique in scanning electron transmission microscopy mode. Results showed that the three dopants showed different distribution behaviors. After sintering, Y dopants were predominately distributed in ZrO 2 nanocrystallites, whereas parts of Al and Ca dopants were distributed in ZrO 2 nanocrystallites and part of them co-segregated at the ZrO 2 /SiO 2 heterointerfaces. Meanwhile, the segregation of Ca dopant at some intergranular films among ZrO 2 nanocrystallites was observed. Redistribution of dopants did not occur during annealing.