Journal Covers

In situ measurement of the orientation matrices for the austenite and martensite phases of the alloy Cu₂₅Au₃₀Zn₄₅ across the interface was performed by synchrotron x-ray Laue microdiffraction at the ALS. Together with theoretical calculations, researchers verified directly and quantitatively the factors that contribute to the alloy’s elastically compatible interface, which ultimately leads to the ultralow fatigue property of phase transformation in martensitic materials. The approach can be generalized to characterize the evolution of microstructure when the transport properties are sensitive to the structural compatibility at the heterogenous phase boundaries. Read more »

As information bits of 0s and 1s are stored in crosspoint tantalum oxide memristors, or resistive random access memory (RRAM) cells, nanoscale-resolution in operando x-ray transmission spectromicroscopy is used to directly observe oxygen migration and clustering, revealing an important operation and failure mechanism of RRAM, a frontrunner technology for next-generation computer memory. Read more »

The nearly simultaneous Mott (electronic) and Peierls (structural) transitions in vanadium dioxide are of significant scientific interest and have tremendous technological promise in computing, memory, optics, and micromechanics. The cover features nanoscale-resolution maps of the Mott and Peierls transitions imaged simultaneously by Kumar et al. using state-of-the-art in situ STXM at the ALS. Read more »

Mutations in rhodopsin can cause misfolding and aggregation of the receptor, which leads to retinitis pigmentosa, a progressive retinal degenerative disease. Förster resonance energy transfer (FRET) and Fourier transform infrared (FTIR) microspectroscopy were utilized to probe within cells the structures formed by G188R and P23H opsins. Read more »

The cover shows a scanning electron micrograph of vaterite crystals formed by the sea squirt Herdmania momus. These are the largest single crystals of vaterite ever observed, including biogenic, geologic or synthetic vaterite. Flat crystal faces are uncommon in biogenic crystals, but these crystals are clearly hexagonal pyramids. Pokroy et al. show that these crystals have smooth fracture surfaces; thus, they most likely formed ion-by-ion, rather than by attachment of particles. Narrowly distributed orientations and lack of organics at crystal interfaces suggest a new mechanism of biomineral crystal growth, perhaps spherulitic growth from solution. Read more »

Organic electronics have emerged into a highly interesting field of research with a great variety of applications. P. Müller-Buschbaum and co-workers demonstrate the importance of in situ investigations during the printing process of organic electronics. In situ grazing-incidence wide-angle x-ray scattering is used to follow the crystallization process of highly conductive PEDOT:PSS polymer mixtures. These findings are important for tuning transparent polymeric electrodes for organic electronics. Cover Image by Christoph Hohmann, Nanosystems Initiative Munich (NIM). Read more »

In contrast to noninnocent copper corroles and essentially innocent gold corroles, silver corroles appear to be poised on a knife-edge between the two electronic-structural descriptions. The summit trail of Mount Sir Alexander, a peak of the Canadian Rockies described by mountaineer Chris Goulet as a knife-edge that only a mouse can walk on, provides an Read more »

Profound bias- and time-dependent changes in the electronic structure of graphene-based supercapacitor electrodes are demonstrated under operating conditions via a combination of in operando x-ray spectroscopy and ab initio modeling by J.R.I. Lee and co-workers. The evolution in electronic structure reflects changes in the surface chemistry and morphology induced by polarization of the electrode-electrolyte interface and points to distinct pseudocapacitive and electric-double-layer capacitive channels for charge storage. Read more »