Investigation of microstructure, ferroelectric and dielectric behavior of CaCu3Ti(4−x)MnxO12 perovskites synthesized through semi-wet route

Abstract

The Mn-doped CCTO (CaCu 3 Ti (4−x) Mn x O 12 system x = 0.25, 0.50 and 1.00) ceramic has been synthesized by using metal nitrates and solid TiO 2 powder sintered at 1223 K for 8 h. The crystal phase of CCTMO was confirmed by the XRD at 1223 K for 8 h. The phase-structure, as well as microstructure, was examined by XRD and SEM, respectively. The SEM micrograph revealed the effect of Mn concentration on grain size and grain formation. The bright-field TEM image of the system confirmed the particle size in the range of 22-30 nm. The stoichiometry and purity of synthesized material were observed by EDX. The investigated dielectric permittivity and tangent loss were found to be 150 and 0.6, respectively, at room temperature (10 kHz), which may be used in electronic devices.

Studies of sintering temperature on the microstructure, magnetic and dielectric behavior of CaCu3Ti3.5Mn0.5O12 ceramic synthesized by semi-wet route

“…The increase the grain size with respect to the temperature of CCTMO ceramic may be due to enlarged grain boundary mobility. Figure 3d-f shows the EDX spectra of Mn-doped CCTO ceramic sintered at 1223 K, 1323 K and 1373 K, respectively for 8 h [11], which verify the existence of Ca, Cu, Mn, Ti, and O elements. The weight percentage of Ca, Cu, Mn, Ti, and O elements is presented in Table 1 with different temperatures were confirmed the stoichiometry and purity of the materials.…”

“…The abnormal behavior of CCTO ceramic is most successfully described by the internal barrier layer capacitance (IBLC) model [8,9]. This model suggests that n-type semiconducting grains are separated by insulating barriers corresponding to the Ti-rich secondary phase observed in grains boundaries [10,11], creating a lot of insignificant capacitances and resulting in giant abnormal dielectric constant values. Afterward, the NBLC model also explained the behavior of dielectric constant on the basis of the existence of stacking faults by reconciling the opposing view of the intrinsic and extrinsic nature of Mn-doped CCTO ceramic [7].…”