Dynamic phase transition modeling of potassium niobate under shock compression

The phase transitions of ferroelectric ceramics under dynamic compressions are of importance for materials and applications design. However, there are very few effective methods for describing the shock-induced phase transition process in ferroelectric ceramics, due to the tiny structural volume change during compression. Here the phase transition behaviors of KNbO3 ceramics under compression are studied by measuring electrical responses. A model describing the phase variation in ferroelectric ceramics under uniaxial compressions with respect to pressures has been established, which may provide a reference for studying dynamic phase transitions in ferroelectrics under shock waves. Unlike hydrostatic high-pressure processes, the shock-induced phase transition initiates at relatively low pressures and increases progressively as the pressure rises. Random orientations of the grains in ceramics lead to different pressure conditions of each grain, which is responsible for the gradual phase transition processes. The proportion of phase transitions in three-dimensional space can be visualized using ab initio density functional theory. These findings have significant implications for material design and optimization.