The properties of undoped and La-doped CaCu₃Ti₄O₁₂ (CCTO) ceramics synthesized via solid state reaction under argon environment had been studied. La-doped CCTOs found to have higher dielectric constant than undoped CCTO. X-ray Diffraction (XRD) analysis indicated that all of the samples have single-phase cubic structure (space group) with no trace of other impurity phases. However, compared with undoped CCTO, minor shifts are observed in the peak positions for La-doped specimens, which are attributed to the lattice expansion caused by ionic size effects (as La3+ is bigger than Ca2+). The lattice parameter estimated from XRD patterns of undoped CCTO were found to be 7.348 Å and the increases in lattice parameter of La-doped CCTO from 7.348 – 7.377 Å, suggesting that La ions have effectively substituted into the Ca site of CCTO
