Anisotropic Microestructure Characterization of Coppper Oxide Nanostucture”

A. E. BIANCHI; L. MONTENEGRO; R. VIÑA; G. PUNTE

Arica Chile

Congreso; X Seminario Latinoamericano de Análisis por Técnicas de Rayos X; 2006

A. E. Bianchi, L. Montenegro, R. Viña y G. Punte Lanadi e IFLP. Departamento de Física, Facultad de Ciencias Exactas, UNLP. CC67-1900- La Plata. ARGENTINA. e-mail: bianchi@fisica.unlp.edu.ar Keywords:  Rietveld analysis, Nanostructures, anisotropic microstructure The synthesis of materials and development of devices with new properties by means of the controlled manipulation of their microstructure has become an emerging interdisciplinary field. In particular, nanostructured materials call the attention of many researchers as they may exhibit exceptional physicochemical properties. Grain (or crystallite) size effects and the high densities of grain or phase boundaries, which can be associated to microstrain, are thought to be causes of those properties. Taking into account the basic relevance and possible application in high density recording and medicine of magnetic nanostructures we decided to design experiments which may yield significant information representative of the overall microstructure of a well defined antiferromagnetic nanostructured system. The AF cupric oxide, CuO, was chosen because of its unique bulk properties (e.g. crystal structure[i] and magnetic properties), some of which (like strong antiferromagnetic Cu—O—Cu correlation and static charge ordering), are similar to those found in High Tc superconductor cuprates. Despite being a system far simpler than those cuprates, the nature of many properties of CuO is still unclear, making the system to be the subject of renewed attention. To add to the understanding of the relationship of microstructure characteristics and macroscopic properties in nanostructured CuO and to disclose the influence of the different factors at play we performed isotropic and anisotropic Rietveld analysis of DRX data coming from the starting material and from a sample obtained by HEBM and subjected to different thermal treatments. The comparison of both types of refinements shows that, in spite of fitting improving, the employed anisotropic approximations does not render a satisfactory physical model to account for the material macroscopic properties.                     [i] S. Åsbrink and L. J. Norrby, Acta Crystallogr., Sect. B: Struct. Crystallogr. Cryst. Chem. 26, 8 (1970).