X-ray colour provides direct 3D information in crystallographic texture measurements

Preferred crystal orientation (crystallographic texture) is a common phenomenon in many complex micro- and nanocrystalline materials of biological and synthetic origin. Conventionally, texture determination by XRD involves sample 2D diffraction images combined into 3D information by sample rotation. We have shown that the photon energies (“X-ray colours”) in a white X-ray beam can be exploited to gain direct 3D crystallographic information in texture measurements. The functionality of the method was demonstrated on carbon fibres and lobster cuticle.

Continue Reading

Localised deformation in nickel-titanium shape memory alloy wires

Super elastic nickel-titanium (NiTi) alloys can tolerate large deformations due to a stress-induced martensitic transformation. When NiTi wire is stretched, a propagating macroscopic transformation front moves along the wire, separating transformed and untransformed regions, unlike other materials which deform homogenously. 3D-XRD stress tomography provided scientists with stress and strain tensors in austenite grains near this propagating front, and they could reconstruct a complete 3D picture of the front using digital image correlation and finite element modelling.

Continue Reading

Phonon-mediated passive transport in lipid membranes


Through an experiment at the ESRF, scientists from Brookhaven National Laboratory have found evidence for propagating in-plane transverse phonon modes in a DPPC lipid membrane. These transverse phonon modes exhibit phononic gaps upon temperature increase, providing a direct signature of the existence of transient voids caused by short-lived lipid density fluctuations that mediate solute permeation across the membrane. The finding supports the mechanism of passive transport through entropic expulsion of the solute from higher to lower lipid density regions across the membrane.

Continue Reading

Experimental realisation of single-atom magnets

spotlight256-featureThe existence of single-atom magnets has been proven by X-ray magnetic circular dichroism. Monodisperse holmium atoms adsorbed on a nonmagnetic MgO thin film display magnetic hysteresis up to a temperature of 30 K and with magnetic relaxation time of the order of 1500 s. This stability is exceptional for such tiny structures. This study unveils key factors to improve the stability of atom-sized magnets in a solid state environment.

Continue Reading

New type of charge-ordering transition in the novel iron oxide Fe4O5

spotlight255-featureSynthesis of new classes of compounds can lead to discoveries of novel physical phenomena as well as innovative applications. Fe4O5 is the first member of a very recently discovered family of iron oxides that can be synthesised only under high-pressure conditions. A multi-technique study of Fe4O5 reveals that it undergoes a unique charge-ordering transition below 150 K that involves competing dimeric and trimeric ordering within the chains of Fe ions. This electronic transition drives an intricate incommensurate distortion in its crystal structure.

Continue Reading

X-rays enable a direct view inside biological cells

spotlight254-featureStructures within intact biological cells have been resolved quantitatively at the nanoscale using a combination of ptychography and scanning X-ray nanodiffraction. Employed sequentially, these techniques provided high resolution real space and reciprocal space images while exposing the cells to a comparatively small radiation dose. The structural arrangement and diameter of keratin protein bundles inside epithelial cells was revealed and filament diameters and distances could be derived.

Continue Reading

3D картографирование обратного пространства методами электронной и рентгеновской дифракции в применении к исследованию эпитаксиальных гетероструктур.

241191001462369253Ведение поисковых экспериментов по созданию новых гетероструктур методом эпитаксии является интересным, но не всегда до конца предсказуемым процессом. В идеальном случае эпитаксиальная пленка вырастает на подложке в одной единственной заранее известной ориентации. Однако довольно часто при росте возникают неожиданные эпитаксиальные соотношения, вырастают новые малоизученные метастабильные фазы, появляются разно-ориентированные кристаллические решетки. Эффективным подходом, позволяющим разобраться в кристаллической структуре эпитаксиальных слоев, является применение трехмерного картографирования обратного пространства с помощью дифракционных методов. Помимо сведений о постоянных решетки, о пространственных группах и ориентациях, 3D картографирование позволяет также извлечь информацию о дефектной структуре эпитаксиальных слоев из распределения диффузной интенсивности вне узлов обратной решетки. 

Where science never sleeps

ESR002h Final WEB 1Sleepless night are a common trend among scientists that come to the ESRF to carry out experiments. They all know too well that precious beamtime should be used to the maximum, so working 24 hours a day is not unusual. Now a team from Nature magazine has followed different teams of users at the ESRF for a whole day. The result: an unprecedented insight of life at the ESRF for the general audience.

Continue Reading