Spray drying: The synthesis of advanced ceramics

Spray-drying is a well-known processing technique commonly used for granulating powder materials. In fact, spray drying has been developed for many industrial applications due to its ability to produce high volumes of uniform particles with identical characteristics. An example of this is its extensive use in the ceramic industry coupled with other processing stages like die-pressing. In this report, we discuss the advantages of using the Spray Drying method (SD) in the synthesis and processing of advanced ceramics, through some cases of study which include the preparation of yttrium aluminum garnet -Y₃Al₅O₁₂- (YAG), α-alumina, K_0.5Na_0.5NbO₃ (KNN), (K_0.48Na_0.52)_0.96Li_0.04Nb_0.85Ta_0.15O₃ (KNLNT), and Cu/Mg/Al mixed oxides. The applications of these ceramics include optical, piezoelectric, ferroelectric, structural, ion exchange/adsorption, pharmaceutical, photochemical, and electrochemical. The synthesis of different advanced materials was performed by SD of aqueous solutions and organic compounds. For YAG, KNN, and KNLNT preparation, citric acid was used as a chelating agent, while the synthesis of α-alumina was achieved by using aluminum formate (Al(O₂CH)₃) as a metal-organic precursor. Besides, macroporous Cu/Mg/Al mixed oxides were fabricated by using layered double hydroxides as building blocks and submicrometric polystyrene spheres as pore former agents. The results demonstrate that spherical agglomerates can be obtained in most cases after being calcined, depending upon the equipment operation conditions, composition, concentration, and organic compound content. Furthermore, the agglomerates with narrow size distribution formed by nanometric particles can be produced. This route shows that the calcination temperatures can be reduced considerably compared with the conventional ceramic method. These features demonstrate the feasibility of this method for the synthesis of advanced ceramics.