Abstract
CaCu3Ti4O12 (CCTO) is a novel material with high relative dielectric constant and low loss tangent, CCTO belongs to a family of oxides of the type ACu3Ti4O12 (A=Ca, Cd, Sr, Na, Th). CaCu3Ti4O12 was first reported by Subramanian et al., to have an unusually high dielectric constant (~10,000) at 1 kHz. It is well known that dielectric properties of CCTO are strongly dependent upon the processing conditions as well as on doping. Semi-wet route was used to synthesise samples of CaCu3Ti4O12 and Ca(1-3x/2)LaxCu3Ti4O12 (x=0.01). Analytical grade chemicals, Ca(NO3)2.4H2O, La(NO3)3.6H2O, Cu(NO3)2.3H2O, titanium dioxide and citric acid having purity better than 99.95% were used as starting materials. The formation of single-phase solid solutions was confirmed by the absence characteristic lines of constituent’s oxides in the XRD patterns. Dielectric measurement of undoped and La doped CCTO has been performed using four probe novocontrol set up (ZG4) in a wide range of temperature starting from the room temperature. With La doping in CCTO there is an increase in the value of dielectric constant in comparison to undoped CCTO.
Highlights
CaCu3Ti4O12 (CCTO) is a novel material with high relative dielectric constant and low loss tangent, CCTO belongs to a family of oxides of the type ACu3Ti4O12 (A=Ca, Cd, Sr, Na, Th) [1,2,3]
In the case of polycrystalline ceramics, impedance spectroscopy (IS) studies have revealed that the grains of CCTO have a core– shell structure in which the semiconducting bulk is enclosed by insulating boundaries, and the very high dielectric constant arises due to the Maxwell–Wagner effect [16,17,18,19,20,21,22,23]
X-ray diffraction patterns for CCTO and 1%LaCCTO were recorded in a X-ray diffractometer employing Cu-Kα radiation with a Ni-filter shown in figure 1
Summary
CaCu3Ti4O12 (CCTO) is a novel material with high relative dielectric constant and low loss tangent, CCTO belongs to a family of oxides of the type ACu3Ti4O12 (A=Ca, Cd, Sr, Na, Th) [1,2,3]. In the case of polycrystalline ceramics, impedance spectroscopy (IS) studies have revealed that the grains of CCTO have a core– shell structure in which the semiconducting bulk is enclosed by insulating boundaries, and the very high dielectric constant arises due to the Maxwell–Wagner effect [16,17,18,19,20,21,22,23]. These high dielectric constant ceramics can be used as dispersion in polymer matrix to develop polymer ceramic composites for embedded capacitor applications
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