The crystal structures of three nepheline samples, (1) K1.91 Na6.04 Si8.15 Al7.72 Fe0.10 O32, a 9.9995(6), c 8.384(2) Å, P63, Z = 1, Dx = 2.673 g cm–3, from the Khibina–Lovozero complex, Kola Peninsula, Russia, (2) K1.60 Na6.21 Ca0.08 Si8.44 Al7.43 O32, a 9.985(1), c 8.372(1) Å, P63, Z = 1, Dx 2.660 g/cm3, from Bancroft, Ontario, Canada, and (3) K1.76 Na5.86 Ca0.13 Si8.12 Al7.84 Fe0.04 O32, a 9...

Mitigation of the global energy crisis requires tailoring the thermal conductivity of materials. Low thermal conductivity is critical in a broad range of energy conversion technologies, including thermoelectrics and thermal barrier coatings. Here, we review the chemical trends and explore the origins of low thermal conductivity in crystalline materials. A unifying feature in the latest material...

Reaction between Cp*TaCl4 (Cp* = h5-C5H5) and BH3·thf at 40 °C yields the pale red electronically unsaturated cluster Cp*TaCl2B4H8 1 which despite having two electrons fewer than the seven pairs required for the observed square pyramidal geometry is stable in air; viewed as a cluster, 1 is the first example of an unsaturated cluster containing a single metal atom; viewed as a chiral 16-electron...

We propose to use the concept of chiral space groups used by the crystallography science to define and design lattice robots. Chiral space groups are of great interest because they give all possible sets of discrete displacements having a group structure and a translational symmetry. We explain the analogy between lattice robot kinematics and crystal symmetry, and identify three fundamental pro...