Interpretation of diffuse scattering in the high-T_csuperconductor HgBa₂CuO_4+δ

Abstract

Published diffuse X-ray scattering from the high-T c superconductor HgBa 2 CuO 4+ has been reexamined with a view to developing a model that more satisfactorily accounts for the observed patterns. The present work agrees with the previous conclusion that the doping oxygen atoms form long and isolated interstitial chains that run in both tetragonal directions. However, a distinctly different model is proposed for the accompanying displacement patterns of the atoms surrounding these linear defects. In this new model it is proposed that it is the correlated shifts of the Ba atoms along the length of the defect chains that are the primary source of the observed scattering, and that the variations of intensity in the generated diffuse streaks of scattering originate from lateral shifts of both Hg and Ba atoms away from defects. The new model yields diffraction patterns that are in much more convincing agreement with the observations than the original model.

Local disorder in Na0.5Bi0.5TiO3-piezoceramic determined by 3D electron diffuse scattering

“…Computer simulations of disordered structures can aid the interpretation of diffuse scattering data and both qualitative and quantitative models can be obtained in this way 56,57 . In the present work DISCUS 47,48 was used to develop a model for the local disorder in 85NBT-10BKT-5BT ternary ceramic that explains the observed superstructure reflections and diffuse scattering intensities.…”

Magnetic structure of paramagnetic MnO

“…6,9,23) and short-range spin correlations persist to T 1100 K. 12,24 Yet, all previous measurements have been restricted to either individual reciprocal-space planes or the powder average, limiting the information content of the scattering pattern. 25 Advanced neutron-scattering instruments now allow measurement of essentially-complete threedimensional (3D) diffuse-scattering patterns, 26,27 but a key problem remains: analysis of these very large datasets is usually computationally prohibitive. 25 Here, we develop an approach to allow rapid refinement of an atomic-scale model to magnetic diffuse-scattering datasets containing > 10 6 data points.…”

“…25 Advanced neutron-scattering instruments now allow measurement of essentially-complete threedimensional (3D) diffuse-scattering patterns, 26,27 but a key problem remains: analysis of these very large datasets is usually computationally prohibitive. 25 Here, we develop an approach to allow rapid refinement of an atomic-scale model to magnetic diffuse-scattering datasets containing > 10 6 data points. We demonstrate the success of this approach by fitting to the complete 3D magnetic diffuse-scattering pattern for MnO, allowing us to determine the relationship between PM and AFM structures.…”

Making sense of vacancy correlations with single-crystal diffuse scattering data

“…Recent developments in instrumentation and computing have made the measurement of single-crystal diffuse scattering much easier than it was even ten years ago (Ye et al, 2018;Keen et al, 2015). Valuable data can also be obtained with lab-based X-ray sources and electron sources, which are able to produce high-quality data in a carefully chosen set of planes (Izquierdo et al, 2011;Welberry & Goossens, 2016). However, the analysis of such data can still seem a daunting task, especially when compared to the powder-based PDF data.…”