In the present study, we reported t

In the present study, we reported the CSP of BaTiO3 with Sr(OH)2·8H2O as a new sintering flux. The obtained samples exhibited high relative densities > 91 % and high room temperature relative permittivities > 1000, with shifts of XRD peaks towards high angles and Curie temperatures towards low temperatures, indicating the formation of Ba1-xSrxTiO3 in cold sintered samples. These results suggested that the Sr(OH)2·8H2O acted both as a flux and a doping additive for CSP of BaTiO3. Furthermore, we successfully visualized with TEM-EDS newly precipitated grains (Ba1-xSrxTiO3) formed through the chemical transformation processes during CSP. In our experimental conditions (275 °C, 1h, 350MPa), we found that most of the grains kept their initial composition, indicating the densification in CSP is governed at solid/flux interfaces. In addition, the presence of the Sr-poor grain boundaries, which is influenced by the applied pressure direction, consistent with a pressure solution creep mechanism driving the densification of ceramics at low temperatures. The experimental findings can aid in the design, discovery, and fabrication of new materials.