Dielectric behavior of CaCu3Ti4O12 electro-ceramic doped with La, Mn and Ni synthesized by modified citrate-gel route

Abstract

Abstract:The effect of La 3+ , Mn 2+ and Ni 2+ doped calcium copper titanate, CaCu 3 Ti 4 O 12 (CCTO), at higher concentrations (CR1 and CR2 with 5 mol% and 10 mol%, respectively), has been examined by semi-wet route at relatively lower temperature. This semi-wet route employs citrate-nitrate gel chemical method using TiO 2 solid powders. X-ray diffraction (XRD) analysis confirms the formation of single phase in the doped samples sintered at 900 ℃ for 8 h. Scanning electron micrographs (SEM) show that the average grain size for CR2 is larger than that of CR1 composition. The energy dispersive X-ray spectroscopy (EDX) is used to study the percentage compositions of different ions present in both ceramics. Dielectric constant (ε r ) and dielectric loss (tanδ) values of CR1 are comparatively higher than those of CR2 ceramic at all measured frequencies and temperatures. The nature of temperature-dependent relaxation behavior of the ceramics is also studied by impedance, modulus spectroscopic analysis and confirms Maxwell-Wagner relaxation.

Dielectric studies of a nano-crystalline CaCu2.90Zn0.10Ti4O12 electro-ceramic by one pot glycine assisted synthesis from inexpensive TiO2 for energy storage capacitors

“…These values also agreed with the value reported earlier for the Maxwell-Wagner relaxation arising from the interfacial polarization for CCTO ceramics, which conrmed the temperature dependence of dielectric properties. 53,54 In order to investigate the relaxation mechanism of the ceramic, the representative electrical modulus of CCZTO_20h has been introduced due to its special advantage of suppressing the electrode polarization effect. The electrical modulus can be calculated from the following equation: where M 0 , M 00 and, 3 0 , 3 00 are the real and imaginary parts of the electric modulus and dielectric constants, respectively and C 0 represents the vacuum capacitance of the sample holder and the electrode arrangement.…”

Dielectric properties of CaCu3-xMgxTi4O12 (x=0.20 and 0.50) material synthesized by the semi-wet route for energy storage capacitor

“…The origins of semi-conductive grains and highly resistive grain boundary were not established, but two models, oxygen loss and oxygen stoichiometric have been proposed. The dielectric response of this material was found to be very sensitive to the microstructure (such as grain size) and processing condition [16] as well as doping [17,18]. There are many examples for doping effects of different ions in the literature such as substitution of Mn, Zn and Mg for Cu [19][20][21][22][23][24], La for Ca [25,26], W for Ti site [27].…”

Dielectric properties of CaCu3Ti4O12ceramics with Zn substitution for Cu

“…10,11 Recently, much work based on partial substitution of Cu with transition ions has been shown to increase the dielectric constant of CCTO dramatically. [12][13][14][15][16][17][18] Among these dopants, Zn has been reported to improve dielectric response and sinterability in a certain extent due to the modification of mixed valent structure. [15][16][17][18] This may be ascribed to the complex valence of copper ions changed with Zn doping in CCTO with Jahn-Teller effect as reported.…”

“…[12][13][14][15][16][17][18] Among these dopants, Zn has been reported to improve dielectric response and sinterability in a certain extent due to the modification of mixed valent structure. [15][16][17][18] This may be ascribed to the complex valence of copper ions changed with Zn doping in CCTO with Jahn-Teller effect as reported. 13 In these literatures, the Zn substitution for Cu was only up to x50?1 in CaCu 3-x Zn x Ti 4 O 12 due to the relative lower sintering temperature (1000uC).…”