Enhanced dielectric response of GeO2-doped CaCu3Ti4O12 ceramics

Abstract

Articles you may be interested inRoom temperature magnetic and dielectric properties of cobalt doped CaCu3Ti4O12 ceramics CaCu 3 Ti 4 O 12 ceramic samples were prepared by solid state conventional route using stoichiometric amounts of CuO, TiO 2 , and CaCO 3 . Afterward the material was doped with GeO 2 with concentrations up to 6% by weight and sintered at 1050°C for 12 h. The influence of doping on the microstructure, vibrational modes, and dielectric properties of the material was investigated by x-ray diffraction, scanning electron microscopy coupled with an energy dispersive spectrometer, and infrared and dielectric measurements between 100 Hz and 30 MHz. The materials presented huge dielectric response, which increases with doping level relative to undoped CaCu 3 Ti 4 O 12 . The main effect of doping on the microstructure is the segregation of Cu-rich phase in the ceramic grain boundaries. Cole-Cole modeling correlates well the effects of this segregation with the relaxation parameters obtained. The intrinsic phonon contributions for the dielectric response were obtained and discussed together with the structural evolution of the system.

Colossal dielectric constant of poly- and single-crystalline CaCu3Ti4O12 fibres grown by the laser floating zone technique

“…As mentioned above, the EDS analysis of the secondary phase revealed a cooper-rich phase segregated in the intergranular regions. This is in accordance with previous works where polycrystalline CCTO samples were prepared by a conventional solid-state reaction route and sintered at different temperatures, the corresponding micrograph exhibiting the presence of large grains of CCTO phase surrounded by a rich Cu phase and deficient in Ca and Ti [23][24][25].…”

Dielectric properties of soft chemical method derived CaCu3Ti4O12 thin films onto Pt/TiO2/Si(100) substrates

“…However, we can detect other peaks, which are not predictable by the CCTO structural models [31]: 143 cm −1 and 623 cm −1 . These lines can be associated to the Raman active normal modes of the small minority phases TiO 2 (anatase phase) and CuO [32,33], respectively located at the grain boundary. The Raman band assigned to TiO 6 structural units seems to be merged with symmetric stretching vibration of Cu-O-Cu band indicating possible linkages of the type Cu-O-Ti, in the network [34].…”

Relationship between microstructural evolution and electric properties of B2O3–CaCu3Ti4O12 composite ceramics

“…Both the 5-and 8%-B 2 O 3 pellets have large grain resistivity values *140 and 120 X cm. This could be explained from the viewpoint of oxygen vacancies [13,14], which is closely related to conducting carriers. It is reasonable to assume that the addition of B 2 O 3 (5 and 8%) surrounds the CCTO grains and prevents the formation of oxygen vacancies from escaping, resulting in the R g increase.…”