Separation of lattice structural and electronic effects on physical properties with nanotechnology

Abstract

Physical properties of electronic and photonic materials can be significantly modified by partial altervalent/aliovalent chemical substitutes. The modification arises from the subtle interplay between the competing/cooperating effects of the electron and lattice structural variations, which are induced by the different charge and atomic radii of the substituents. To understand these effects, it is necessary to isolate the electronic and crystallographic contributions to the particular physical property to arrive at a fundamental understanding of the underlying dominant mechanism. Intrinsic properties amplified nanomaterials/nanoparticles is a newly developed technique which can experimentally discriminate lattice structural effects from electronic contributions to physical properties by exploiting the nanosize dependence of lattice structure to modify the structural parameters without resorting to chemical doping. In this work, we demonstrate a separation of structural and electronic effects on superconducting critical temperatures (T _c ) of MgB₂ and YBa₂Cu₃O_7-x, and also on emission behavior of ZnO. The results show that the superconductivity of MgB₂ is extremely sensitive to lattice parameter variation while T _c of YBa₂Cu₃O_7-x is more sensitive to electronic structure. The effects of the lattice and electronic structures on the emission behavior of ZnO are complex and the structural variations make different contributions to the behavior in the particular conditions.