An effective strategy to inhibit grain coarsening: Construction of multi-element co-segregated grain boundary complexion

When exposed to moderate to high temperatures, nanomaterials typically suffer from severe grain coarsening, which has long been a major concern that prevents their wider applications. Here, we proposed an effective strategy to inhibit grain coarsening by constructing grain boundary (GB) complexions with multiple dopants co-segregated, which hindered coarsening from both energetic and kinetic perspectives. As a demonstration of the feasibility of the strategy, multiple selected dopants were doped to a ZrO₂-SiO₂ nanocrystalline glass-ceramic (NCGC) to form GB complexions. Results showed that the NCGC was predominately composed of ZrO₂ nanocrystallites (NCs) distributed in an amorphous SiO₂ matrix. Ultrathin layers of GB complexions (~2.5 nm) were formed between adjacent ZrO₂ NCs and they were crystalline superstructures with dopants co-segregated. In addition, a small amount of quartz solid solution was formed and it adhered to the periphery of ZrO₂ NCs and bridged the adjacent NCs, acting as "bridging phase". The GB complexions and the "bridging phase" and synergistically enhanced the coarsening resistance of ZrO₂ NCs up to 1000 ºC. These findings are important for understanding the GB complexions and are expected to provide new insights to design nanomaterials with excellent thermodynamic stability.