Structural and Electrical Properties of Na2Pb2Dy2W2Ti4Ta4O30 Ceramic

The structural, ferroelectric, and electrical properties of tungsten bronze Na2Pb2Dy2W2Ti4Ta4O30 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.