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The Mössbauer spectra of 119Sn in PbZr1-xSnxO3 compound were studied from 30 to 300°C with particular emphasis on the regions of phase transitions. Some changes of the Mössbauer spectrum near the phase transition temperatures were observed, as expected from the change in the crystal structure. The measurements also showed that the Mössbauer fraction considerably drops near the temperature of the phase displacive transition between two antiferroelectric phases (AFE1–AFE2), whereas this drop is considerably smaller at Curie point. Little difference was found in the center shift of the spectrum, indicating that the bonding character is not affected by the phase transitions. The obtained results were interpreted according to Dvorak’s suggestion that in antiferroelectrics the frequency over the entire optical branch may soften at particular phase transitions. According to the theory, the mode softening should manifest as a decrease in the Mössbauer–Lamb recoil-free fraction (f-factor) due to the increasing vibrational amplitude of the soft mode. Such softening was already observed in Raman scattering measurements in the PbZr1-xSnxO3 single crystals. [ABSTRACT FROM AUTHOR]

The multireflection grazing-incidence X-ray diffraction (MGIXD) method is commonly used to determine a stress gradient in thin surface layers (about 1-20 µm for metals). In this article, the development of MGIXD to enable the determination not only of stresses but also of the c/ a ratio and the a0 strain-free lattice parameter in hexagonal polycrystalline materials is presented and tested. The new procedure was applied for the results of measurements performed using a laboratory X-ray diffractometer and synchrotron radiation. The evolution of stresses and lattice parameters with depth was determined for Ti and Ti-alloy samples subjected to different mechanical surface treatments. A very good agreement of the results obtained using three different wavelengths of synchrotron radiation as well as classical X-rays (Cu Kα radiation) was found. [ABSTRACT FROM AUTHOR]

The physical and electrical properties of a silicon nanowire reconfigurable field effect transistor (RFETs) are determined by the Schottky junction between the participating phases. TEM studies on such junctions require a careful FIB-based target preparation of thin lamellae with minimal ion-beam induced damage. In the current study, the nickel silicide phase forming the Schottky junction with silicon is identified using EDX in the TEM, considering a calibration based on the Fourier transforms of the HRTEM micrographs of known diffraction patterns of the nickel silicide phases. The TEM lamellae are prepared using the so-called lift-out technique and low voltage Ga+ ion polishing to minimize the near-surface amorphization. The structural and compositional data of the nickel silicide phase are needed for engineering the Schottky junction and corresponding theoretical modeling. [ABSTRACT FROM AUTHOR]

The pteropod Cuvierina constructs very lightweight, thin, flexible, and resistant shells with the most unusual microstructure: densely packed, continuous crystalline aragonite fibers that coil helically around axes perpendicular to the shell surface. The high degree of fiber intergrowth results in a particular interlocking structure. The shell is constructed by guided self-assembly, outside the animal's soft body. A prerequisite to understand its formation is to resolve the underlying crystallographic building principle. This is basic in order to use this hierarchically structured and highly functional biomaterial as inspiration for the production of new materials. It teaches us about the optimization of structures over millions of years of evolution under strict consideration of energetic costs and efficient use of available resources and materials. We have described how helical coiling proceeds by using a combination of diffraction and imaging techniques, which complement at different levels of resolution. Despite their curling, the fibers are continuously crystalline and show a preferred crystallographic growth direction. When the latter can no more be maintained due to the imposed curving, abrupt changes across twins permit to continue growth in the desired direction. This is a nice example of how crystallographically continuous fibers can grow helically. [ABSTRACT FROM AUTHOR]