Role of ionic and nonionic surfactant on the phase formation and morphology of Ba(Ce,Zr)O₃ solid solution

Ceramic powder of BaCe_0.54Zr_0.36Y_0.1O_2.95 (BCZY) was successfully synthesized via a modified sol–gel method using metal nitrate salts as precursors. The synthesis was accomplished by using three different types of surfactants which are cationic (benzalkonium chloride), anionic (sodium dodecyl sulfate) and a nonionic surfactant (polyoxyethylene (10) oleyl ether). Citric acid and ethylene glycol were used as a chelating and a polymerization agent, respectively. The crystal form and morphology of the powders were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometer and scanning electron microscope (SEM). FTIR spectra showed the traces of carbonate residues in all samples due to the presence of hydrocarbon group in the surfactant structure even after calcination process at T = 1100 °C. Samples prepared using cationic and anionic surfactant consists of the multi-phases compounds which are dominated by BaCO₃, BaCeO₃, CeO₂ and BaZrO₃. On the other hand, the samples prepared by using nonionic surfactants produce a single phase of BCZY perovskite-type oxide. SEM images revealed that the sample prepared without surfactant exhibits severe agglomeration. Morphology of the particles for the BCZY prepared by applying the cationic and anionic surfactant was, respectively, cubical and spherical in shape. As for nonionic surfactant, the particle obtained was spherical and uniform in shape. The optimum result was obtained by adding a nonionic surfactant, Brij97, which indicates high crystallinity of the BCZY powder at a temperature of 950 °C and the particle size ranging from 20 to 80 nm. It can be concluded that surfactant affects the phase formation of BCZY ceramic powder as well as its morphology.