Low-toxic gelcasting of giant dielectric-constant CaCu₃Ti₄O₁₂ ceramics from the molten salt powder

CaCu₃Ti₄O₁₂ (CCTO) nano powder was synthesized using a molten salt synthesis method in NaCl flux. Synthesis temperature and holding time were investigated. The suitable synthesis condition is 800°C for 2h. Aqueous CCTO slurry with high solid loading and low viscosity was prepared by using acrylic acid-2-acrylamido-2-methypropane sulfonic acid copolymer (AA/AMPS) as the dispersant. AA/AMPS dosage and pH condition have been optimized as AA/AMPS dosage of 3wt% and pH about 9.08. A low-toxicity and water-soluble monomer, N,N-dimethylacrylamide (DMAA) was used as the gelling agent. CCTO green body fabricated by the gelcasting method has the homogeneous microstructure and relatively high mechanical strength of 9.27MPa. CCTO ceramics obtained by the gelcasting method have higher dielectric constant than those prepared by the cold isostatic pressing method and show relatively low dielectric loss of below 0.2 in the wide frequency range of 10²-10⁵Hz.