Buffering Octahedra in MoZrP: Intergrowth as a Solution to the Frustrated Packing of Tricapped Trigonal Prisms and Icosahedra.

Atomic packings based on icosahedra and tricapped trigonal prisms are prone to frustration─indeed, these polyhedra represent common configurations in metallic glasses. In this Article, we illustrate how these packing issues can serve as a driving force for the formation of modular intermetallic structures. Using Density Functional Theory-Chemical Pressure (DFT-CP) analysis, we relate the HfMoB-type structure of MoZrP to interatomic pressures experienced by the atoms in two parent structures: ZrP, whose structure is built from tricapped trigonal prisms, and ZrMo, a Laves phase containing icosahedra.

At the Limits of Isolobal Bonding: π-Based Covalent Magnetism in MnHg.

Magnetic ordering in inorganic materials is generally considered to be a mechanism for structures to stabilize open shells of electrons. The intermetallic phase MnHg represents a remarkable exception: its crystal structure is in accordance with the 18- bonding scheme and non-spin-polarized density functional theory (DFT) calculations show a corresponding pseudogap near its Fermi energy. Nevertheless, it exhibits strong antiferromagnetic ordering virtually all the way up to its decomposition temperature.

Templating Structural Progessions in Intermetallics: How Chemical Pressure Directs Helix Formation in the Nowotny Chimney Ladders.

In the structural diversity of intermetallic phases, hierarchies can be perceived relating complex structures to relatively simple parent structures. One example is the Nowotny Chimney Ladder (NCL) series, a family of transition metal-main group (T-E) compounds in which the T sublattices trace out helical channels populated by E-atom helices. A sequence of structures emerges from this arrangement because the spacing along the channels of the E atoms smoothly varies relative to that of the T framework, dictated largely by optimization of the valence-electron concentration.

Pseudogap Control of Physical and Chemical Properties in CeFeSi-Type Intermetallics.

We describe the synthesis of the new ternary compound CaRuSi whose chemical and physical properties help draw a clear picture of how electronic structure controls the behavior of an isostructural series of intermetallics. DFT calculations reveal that an electronic pseudogap arises near the Fermi level ( E), corresponding to 14 valence electrons per RuSi unit. The closed-shell-like character is further investigated by comparisons with the electronic structures of CaCoSi (15 electrons), where the E lies above the corresponding pseudogap, and its hydride CaCoSiH, where formation of H anions restores the 14-electron count on the metal sublattice, returning the E to the pseudogap.

Reconstruction control of magnetic properties during epitaxial growth of ferromagnetic Mn3-deltaGa on Wurtzite GaN(0001).

Binary ferromagnetic Mn(3-delta)Ga (1.2<3-delta< or =1.5) crystalline thin films have been epitaxially grown on wurtzite GaN(0001) surfaces using rf N-plasma molecular beam epitaxy.

Scanning tunneling microscopy and surface simulation of zinc-blende GaN(001) intrinsic 4x reconstruction: linear gallium tetramers?

Scanning tunneling microscopy images confirm electron diffraction studies that the zinc-blende GaN(001)-4x reconstruction consists of rows aligned along [110] with a spacing along [110] of 4a. Dual-bias imaging shows a 180 degree shift of the corrugation maximum position between the profiles of empty and occupied states, in agreement with surface simulations based on the 4 x 1 linear tetramer model of Neugebauer et al. [Phys.