New negative temperature coefficient ceramics in Zr-doped CaCu3Ti4O12 system

In this study, negative temperature coefficient (NTC) ceramics based on CaCu 3 Ti 4- x Zr x O 12 (0 ≦  x  ≦ 0.15) compositions have been successfully synthesized by traditional solid-state method. X-ray diffraction results show that the major phase of all samples is CaCu 3 Ti 4 O 12 (CCTO) phase with body-centered cubic structure. The substitution of Zr 4+ for Ti 4+ inhibits the grain growth of CaCu 3 Ti 4- x Zr x O 12 ceramics and greatly reduces the grain size . The results of X-ray photoelectron spectroscopy fully confirm the coexistence of Cu + /Cu 2+ and Ti 3+ /Ti 4+ ions, which are one of the important reasons for conductivity of CaCu 3 Ti 4- x Zr x O 12 samples. There is a good linear relationship between the natural logarithm of resistivity and reciprocal temperature of all ceramic samples, which is consistent with NTC behavior. The obtained values of ρ 150 , B 150/550 and E a of the sintered samples are in the range of 1.62 × 10 5 –3.39 × 10 5  Ω cm, 6378–6593 K and 0.550–0.568 eV, respectively.