ABSTRACT

Metal oxides belong to a fascinating class of natural materials that exhibit a wide range of properties and phenomena ranging from insulating to semiconducting to conducting to superconducting, from diamagnetic to paramagnetic to ferromagnetic to antiferromagnetic, and from dielectric to ferroelectric to piezoelectric to antiferroelectric. They have been found to be important for many scientific studies and technological applications, such as sensors, catalysts, capacitors, dielectric and ferroelectric devices, optoelectronic devices, and many others. This class of materials has motivated scientists and engineers to investigate systematically their synthesis processing, microstructures, and physical properties. Many of these novel materials are related to the perovskite ABO3 family, as seen in Figure 1, where the [BO3] is a host lattice with corner-sharing BO6 octahedra. Since the discovery of high-Tc (transition temperature) superconductivity in copper oxide compounds, a large number (nearly 1000 compounds) of cuprate superconductors with different structural types have been discovered and they are found to have a deformed perovskite layer. Details will be discussed in Section II.