Structural and electrical properties of Na2Pb2Eu2W2Ti4X4O30 (X=Nb, Ta) ferroelectric ceramics (original) (raw)

The structural, ferroelectric, and electrical properties of tungsten bronze Na 2 Pb 2 Dy 2 W 2 Ti 4 Ta 4 O 30 ceramic, synthesized by a standard high-temperature solid-state reaction route, have been studied. Formation of a single-phase orthorhombic crystal system was verified by x-ray diffraction analysis. Microstructural analysis of a pellet sample by scanning electron microscopy revealed well-defined grains of almost the same dimension, uniformly distributed on the surface. Detailed studies of the dielectric properties of the compound as a function of frequency and temperature showed that the compound undergoes a ferroelectric-paraelectric phase transition of diffuse type. The frequency dependence of the alternating-current (ac) conductivity showed the signature of Jonscher's universal power law. Conductivity study over a wide temperature range suggested that the compound exhibits negative temperature coefficient of resistance behavior.