Multiscale phase separation in complex systems by high resolution X-ray diffraction



Multiscale phase separation in complex systems by high resolution X-ray diffraction


G. Campi, A. Pifferi


Structural phase transition (SPT); X-ray microdiffraction; Complex systems; Critical self organization


Università di Roma "La Sapienza", dipartimento di Fisica; European Synchrotron Radiation Facility (ESRF); Italian Synchrotron Radiation Facility (Elettra)


High-temperature superconductive compounds, such as cuprates, diborides and picnitides are studied by high-resolution and space resolved synchrotron X-ray diffraction experiments performed on the XRD1 and ID13 beamlines at Elettra and ESRF, in collaboration with the Physics Department of Rome University "La Sapienza" ( In these complex materials, inhomogeneities and phase separation on different scales of lengths associated with local organization and/or disorder occur [1], requiring a deeper exploration of reciprocal space by measuring the "diffuse scattering" beyond the Bragg peaks and conventional crystallography. Furthermore, local organization could arrange in intriguing way in real space giving rise to substructures playing relevant roles in material functionality, Therefore, to image local organization we need high resolution in scanning synchrotron X-ray diffraction, which combines high wavenumber resolution in reciprocal space with sub-micrometric resolution in real space. We found that in the oxygen doped La2CuO4+y, the superconducting Tc is promoted by ordering of doping interstitial oxygen in microstructures with fractal distribution [2]. Further investigations are in progress both to study microstructure formation in different systems and to get deeper insights on their nature, by studying them under different stimuli [3,4].


Multiscale phase separation in complex systems by high resolution X-ray diffraction

Fig. 1: A) Experimental setup of micro-diffraction scanning experiment; B) diffraction recording by CCD detector around the (006) Bragg peak in La2CuO4.1: satellite reflections associated to interstitial oxygen ordering is observed; C) space resolved satellite reflection intensity.

[1] A. Bianconi. G. Campi, S. Agrestini, D. Di Castro, M. Filippi, C. Dell'Omo, Micro-strain and self-organization of localized charges in copper oxides, in "Intrinsic Multiscale Structure and Dynamics in Complex Electronic Oxides", A. R. Bishop, S. R. Shenoy S. Sridhar Editors World Scientifics, 165, 2002.

[2] M. Fratini, N. Poccia, A. Ricci, G. Campi, M. Burghammer, G. Aeppli & A. Bianconi, Scale-free structural organization favoring high temperature superconductivity, Nature, 466, 841-844 (2010)

[3] G. Campi, C. Dell'Omo, D. Di Castro, S. Agrestini, M. Filippi, G. Bianconi, L. Barba, A. Cassetta, M. Colapietro, N. L. Saini, and A. Bianconi, Effect of Temperature and X-ray Illumination on the Oxygen Ordering in La2CuO4.1 Superconductor, J. of Superconductivity 17, 137 (2004).

[4] N. Poccia, M. Fratini, A. Ricci, G. Campi, L. Barba, A. Vittorini-Orgeas, G. Bianconi, G. Aeppli, A. Bianconi, Evolution and Control of Phase Separation in Complex Cuprate Superconductors, submitted to Nature Materials

[5] G. Bianconi, D. Di Castro, N. L. Saini, A. Bianconi, M. Colapietro and A. Pifferi, Charge stripes formation by X-ray illumination in high Tc superconductors in X-RAY AND INNER-SHELL PROCESSES, Edited by R. W. Dunford, D. S. Gemmell, E. P. Kanter, B. Krässig, S. H. Southworth, and L. Young, AIP Conference Proceedings 506, 358-370 (Woodbury, New York, (2000)


Gaetano Campi
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Last Updated (Tuesday, 21 December 2010 16:00)