Influence of the processing rates and sintering temperatures on the dielectric properties of CaCu3Ti4O12 ceramics

Abstract

The stoichiometric CaCu 3 Ti 4 O 12 pellets were prepared by the solid state synthesis. X-ray diffraction data revealed the tenorite CuO and cuprite Cu 2 O secondary phases on the unpolished CaCu 3 Ti 4 O 12 samples regardless of the heating rates. Also, the dielectric constant marked the highest for the CaCu 3 Ti 4 O 12 sample sintered at the lowest heating rate (1°C/min), which was explained by the increased grain conductivity due to the cation reactions. On the other hand, Cu 2 O phase was found only on the unpolished CaCu 3 Ti 4 O 12 sample sintered over 1100°C and those are considered as the remains reduced from the CuO phase. The higher sintering temperature showed the increased dielectric constant and the loss tangent of the CaCu 3 Ti 4 O 12 samples, and this result could be interpreted by the impedance measurement data. The relationship between the processing condition and the dielectric properties was discussed in terms of the cation non-stoichiometry and the defect chemistry in CaCu 3 Ti 4 O 12 .

Effective dielectric loss (tan δ) reduction of CaCu3Ti4O12 (CCTO) via various addition of glasses

“…Several approaches have been used to reduce tan δ of CCTO through the application of different processing parameters, doping different elements into CCTO or combining it with another material to produce composite . One of the most interesting approaches is by fabrication of CCTO composites via incorporation of glass as additive.…”

Full Range Dielectric Characteristics of Calcium Copper Titanate Thin Films Prepared by Continuous Composition-Spread Sputtering

“…Dielectric materials, particularly those having higher dielectric constant k and less dependence on temperature within the operational ranges of frequency and temperature, have been regarded as promising for very recent electronic applications demanding the minimization of the occupancy volume of components. Although conventional high k ferroelectric materials, including BaTiO 3 , MgSnO 3 , SrTiO 3 , and Pb(Mg 1/3 Nb 2/3 )O 3 , have been actively utilized for commercial components, there has always been demand for higher k and better stability against degradation by high temperature. − As an alternative candidate, another perovskite calcium copper titanate having stoichiometric CaCu 3 Ti 4 O 12 composition has emerged, mainly due to its unusually high dielectric performance. , Bulk CaCu 3 Ti 4 O 12 materials have giant permittivity of ∼10 4 ∼10 5 at kHz and the least dependence of k over the broad temperature range from 100 to 400 K. , …”

Phase structure, microstructure and broadband dielectric response of Cu nonstoichiometry CaCu3Ti4O12 ceramic

“…For CCTO polycrystalline, the semiconductivity of grains relies on the oxygen vacancies [9][10][11] and cation nonstoichiometry [12,13], while the resistivity of grain boundaries is due to the presence of CuO intergranular layers [8] and structural defects (i.e. twin boundaries of nanodomains) [5,7].…”