Nanostructured Ceramics - Synthesis and Understanding

Sammanfattning: During the last years, nanostructured ceramics have been favored for use in the industry due to their beneficial properties. For example, calcium phosphate ceramics with their biocompatible and bioactive characteristics are beneficial in biomedicine. On the other hand, silica-based nanoporous materials with large specific surface areas are efficient in adsorption applications. In such materials, the structure is the basis for efficiency in the mentioned applications. This investigation was conducted to understand the structure and its relation to the synthesis process. Two types of materials were investigated: silica-based nanoporous materials under the family name of Quartzene® and calcium phosphate ceramics. We have used different analysis methods, e.g., electron microscopy, nitrogen adsorption, and x-ray diffraction, to characterize the materials and understand the structure. We observed that similar synthesis processes could lead to different structures that were efficient for different applications, e.g., adsorption. The relation between the structure of Quartzene® and its efficiency in the adsorption application is discussed. Various factors (e.g., cleaning method and the storage time/conditions) influenced the resulting structures. Calcium phosphates were produced in aqueous solutions, and the effect of residual ions combined with various reaction temperatures and time was studied. We observed that the combination of residual ions and varying reaction temperature and time could influence the formation of the intermediate phase, octacalcium phosphate (OCP), and dicalcium phosphate dihydrate (DCPD), and particle size when the starting ion concentrations were fixed. High reaction temperature (60 °C) induced OCP and higher precipitation efficiency. For future investigation, fine-tuning the synthesis process is recommended to enhance the structure of the materials suitable for industrial use.