In a recent study, researchers at the Ningbo Institute of Material Technology and Engineering (Chinese Academy of Sciences) used a improved precipitation approach for preparing the nanometer-sized CTP materials. As shown in the figure, the silica sphere that can be fabricated controllably into perfectly spherical morphology, is used as the core, Ca2+ protected by citric acid adsorbs at the silica surface, and then the precipitation reaction occurrs at the surface. After the silica spheres was coated with CTP layers, a core/shell CTP materials is obtained, and the shape and size of the materials are controlled by the core.
The results show that the resulting core/shell structural nanoparticles maintain a spherical morphology and a narrow size distribution. When these CTP nanoparticles are dispersed into silicone oil, they exhibit giant ER activity which outclasses that of pure CTP nanoparticles. Furthermore, the core/shell structural CTP materials will cheaper than the pure CTP materials because silica is a kind of comparatively cheap material.
The improved precipitation process provides an efficient approach for preparing GER particles with different forms. Moreover, it can be generalized for bulk synthesis of many other functional materials.