The matrix crystal and the twinned crystal are indicated in blue and orange color, respectively. 77, 3865–3868 (1996).In twinned martensite, a metastable hexagonal ω-Fe phase always exists in the twin boundary region of the body-centered cubic (bcc) -type twinning structure. Generalized gradient approximation made simple. Wien2k, An Augmented Plane Wave+Local Orbitals Program for Calculating Crystal Properties (Schwarz K., Techn. 91, 4673–4676 (1986).Ĭomputer program CrysAlis RED (version 1.171.33) by Oxford Diffraction (now Agilent Technologies). Calibration of the ruby pressure gauge to 800 kbar under quasi-hydrostatic conditions. Calibration of the pressure dependence of the R1 ruby fluorescence line to 195 kbar. Interpenetrating polar and nonpolar sublattices in intermetallics: The NaCd2 structure. Large, larger, largest–a family of cluster-based tantalum copper aluminides with giant unit cells. The crystal structure of the phase β–Mg2Al3. Pressure-induced superconductivity in strontium and barium. Superconductivity of barium under pressure. Pseudopotential theory of cohesion and structure. Structure of barium in three phases under pressure. Crystal structure from one-electron theory. Determination of the Structural Parameters of an Incommensurate Phase from First Principles: The Case of Sc-II. Structure and stability of the modulated phase Sb-II. Exotic high pressure behavior of light alkali metals, lithium and sodium. Potassium under pressure: A pseudobinary ionic compound. Dense low-coordination phases of lithium. Electronic structure and bonding in the C m c a phases of Si and Cs. Hanfland, M., Syassen, K., Christensen, N. The structure of barium in the hexagonal close-packed phase under high pressure. First-principles phonon spectrum in bcc Ba: Three-ion forces and transition-metal behavior. Theoretical and computational study of high-pressure structures in Barium. Simple metals at high pressures: The Fermi sphere-Brillouin zone interaction model. Origin of the complex crystal structures of elements at intermediate pressure. X-ray diffraction study of diffuse scattering in incommensurate rubidium-IV. Chain Melting in the Composite Rb-IV Structure. Correction of X-ray intensities from single crystals containing lattice-translocation defects. WinGX suite for small-molecule single-crystal crystallography. SIR 92-a program for automatic solution of crystal structures by direct methods. Direct observation of a pressure-induced metal-to-semiconductor transition in lithium. High-pressure structural study of barium to 90 GPa. in Science and Technology of High Pressure, Proceedings of AIRAPT-17 (eds Manghnani, M., Nellis, W. Self-hosting incommensurate structure of barium IV. High-pressure structures and phase transformations in elemental metals. Metallic high-pressure modifications of main group elements. On the basis of first-principles electronic structure calculations, pseudopotential theory and an analysis of the lattice periodicities and interatomic distances, we rationalize why the Ba phases with the common densely packed crystal structures become energetically unfavourable in comparison with the complex-structured Ba-IVc phase, and what the role of the well-known pressure-induced s– d electronic transfer is. The existence of such patterning on the nanometre scale points at medium-range interactions that are not fully screened by the itinerant electrons in this metal. It is a commensurate host–guest structure with 768 atoms in the representative unit, where the relative alignment of the guest-atom chains can be represented as a two-dimensional pattern with interlocking S-shaped 12-chain motifs repeating regularly in one direction and repeating with constrained disorder in the other. Using single-crystal synchrotron X-ray diffraction and new data analysis strategies, we have now solved the most complex of these crystal structures, that of phase Ba-IVc at 19 GPa. Elemental barium adopts a series of high-pressure phases with such complex crystal structures that some of them have eluded structure determination for many years.
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