(1) In the case of the congruent dissolution of materials, especially hygroscopic compounds, the CSP is relatively simple and proceeds through a direct method. (2) If the materials are incongruent dissolution, for example, BaTiO3, a passivating surface appears on the surface that prevents the precipitation process and further densification [81]. To solve this issue, a saturated solution at the required stoichiometric ratios is introduced to enable particle rearrangement, growth, and therefore densification.