The Structural, electronic and optical properties of cubic CaCu 3 Ti 4-x Ag x O 12 (x = 0, 0.5, 1, 1.5 and 2) perovskite ceramics have been investigated by the first principle method. The CaCu 3 Ti 4-x Ag x O 12 ceramics still maintains the bcc lattice and the lattice constants increase with the increasing Ag concentration. The formation energies of the CaCu 3 Ti 4-x Ag x O 12 ceramics are all negative, which indicates that the crystal structures of all ceramics are thermodynamically stable. Pure CaCu 3 Ti 4 O 12 ceramic has semiconductor properties, and the spin up and spin down energy band gaps of cubic CaCu 3 Ti 4 O 12 ceramic at the high symmetry point Γ are 1.1891eV and 0.8527eV, respectively. After doping silver, however, the CaCu 3 Ti 4-x Ag x O 12 ceramics show metallic properties. The optical properties such as dielectric function, reflectivity, refractive index, photoconductivity, extinction coefficient, absorption coefficient and energy loss function are also discussed.
