Electronic energy bands of ScH, in the fluorite structure have been calculated by the composite-wave variational version of the APW method. The crystal potential was constructed by superposition of the atomic potential of Herman and Skillman. From the band structure data the density of states (DOS), the joint DOS (JDOS) and the Fermi surface have been worked out. The results of the JDOS calcula...

Four polymorphs of Zn(OH)2 have now been recorded from an oxidised vein exposure near Milltown, Ashover, Derbyshire; sweetite, wfilfingite, ~,-Zn(OH)2, and ashoverite. The last is a new mineral, a tetragonal modification of Zn(OH)2 containing minor quantities of Pb, Cd and Ca. Its unit cell dimensions are a 6.825(2) and c 33.36(4)A, giving V = 1554A3; Z = 32; space group 141/amd, 141 md, or I7~...

Bulk ionic conductivity, Ionic Thermal Current (I.T.C.), and Thermally Stimulated Polarization Current (T.S.P.C.) studies are reported for the system Bal-,LaXF2+, (0.12 x loe2 < x < 0.45). The obtained results are illustrative for the compositional dependence of the ionic conductivity of anion-excess solid solutions. For small solute content simple associates as well as free mobile fluoride int...

The electromc energy band structures of three interrnetalhc compounds have been

—The surface energies, tensions and structures of the (111) and (110) surfaces of CaF2 , SrF2, BaF2 and U 0 2 , Th0 2 , Pr0 2 , Pu0 2 , Ce0 2 have been calculated using an ionic shell model. The surface energies for the natural cleavage plane (111) are compared with the available experimental data and agree well. The surface tensions indicate a compressive stress in both surfaces. The surface s...

We present the results of a plane wave based density functional study of the structure and properties of tetragonal zirconia in the range of pressures from 0 to 50 GPa. We predict a transition to a fluorite-type cubic structure at 37 GPa which is likely to be of a soft mode origin and is accompanied by a power law decrease of the frequency of the Raman-active A(1g) mode. A detailed study of the...

Many of the veins enclosed within the Paleozoic basement of the Catalonian Coastal Ranges show severa1 common characteristics: low temperature of formation (between 75 and 200°C), the presence of complex polisaline fluids and a certain relationship to the pretriassic paleosurface. Mineralogical composition and age are variable, ranging from Pb-Zn veins with carbonate gangue of late Hercynian ag...

Dual functions of BaCe0.8Y0.2O3−a ~BCY! as an electrolyte and as an anode were improved for solid oxide fuel cell ~SOFC! applications. A porous Ce-rich phase with fluorite structure was formed with a depth of ,10 mm from the BCY surface by vaporization of BaO from the BCY surface at 1700°C. The resulting BCY surface showed enough electronic conductivity to provide electrical collection and a hi...