%0 Journal Article
%T Mechanical and Dielectric Behaviour of CaCu3Ti4O12 and Nb Doped CaCu3Ti4O12 Poly(vinylidene fluoride) Composites
%A Anshuman Srivastava
%A Karun Kumar Jana
%A Pralay Maiti
%A Devendra Kumar
%A Om Parkash
%J Journal of Composites
%D 2014
%R 10.1155/2014/769379
%X PVDF has been reinforced with different amount of CaCu3Ti4-5x/4NbxO12 with powder prepared by solid state ceramic method. Composites were prepared by melt extrusion method. Phase composition was studied using powder X-ray diffraction (XRD). Microstructural, dielectric, and mechanical properties have also been studied. These composites have Young¡¯s modulus more than that of pure PVDF. Two dielectric relaxations, one at low frequency and the other at high frequency, have been observed in these composites. Dielectric relaxation at low frequencies is of Maxwell-Wagner type while the one observed at high frequency is due to hopping of electrons among different valent states of transition metal ions. Nature of dielectric relaxation has been analysed using H-N function. 1. Introduction Nowadays, polymer-ceramic composites have gained a lot of interest as potential candidates for many applications such as embedded capacitors, microelectronic packaging, and charge storage devices. Polymers possess good processability, mechanical flexibility and low cost but have very small value of dielectric constant to be useful as capacitors. On the other hand, ferroelectric and relaxor ferroelectric ceramics have high dielectric constant but these are brittle. Dielectric constant of these ceramics is very sensitive to temperature near their transition point. This is not a desirable feature for use of these materials as capacitors. Therefore, polymer-ceramic composites can be a good choice to achieve miniaturisation of energy storage devices by combining the merits of polymers and ceramics [1¨C4]. Barium titanate (BaTiO3, BT), lead zirconate titanate (Pb(Zr,Ti)O3, PZT), and lead magnesium niobate-lead titanate (Pb(Mg1/3Nb2/3)O3PbTiO3, PMNT-PT) have been widely used as fillers by many research groups [5¨C12]. CaCu3Ti4O12 (CCTO) has attracted increasing scientific and technological interest. Being lead-free, it is environment-friendly possessing high dielectric constant which is nearly temperature- (T-) independent in the range 100¨C600£¿K [13, 14]. Dielectric properties of composites depend on the dielectric properties of the ceramic filler, polymer matrix, and the interfaces between the filler and the matrix [3]. At high loading, the filler particles have a tendency to agglomerate resulting in an increase in porosity, decrease in densification, low dielectric constant, poor mechanical properties, and high water absorption. These problems are further enhanced due to difference in the surface characteristics of inorganic filler and the organic matrix. Homogeneous dispersion becomes
%U http://www.hindawi.com/journals/jcomp/2014/769379/