Polymorphous transformations in alkaline-earth silicates

Polymorphous Transformations in Alkaline-Earth Silicates

Thermally induced structural transformations on polymorphous silicon

Polymorphous Si is a nanostructured form of hydrogenated amorphous Si that contains a small fraction of Si nanocrystals or clusters. Its thermally induced transformations such as relaxation, dehydrogenation, and crystallization have been studied by calorimetry and evolved gas analysis as a complementary technique. The observed behavior has been compared to that of conventional hydrogenated amor...

Ferromagnesian postperovskite silicates in the D'' layer of the Earth.

Natural olivine with 12 mol % Fe(2)SiO(4) and synthetic orthopyroxenes with 20% and 40% FeSiO(3) were studied beyond the pressure-temperature conditions of the core-mantle boundary. All samples were found to convert entirely or partially into the CaIrO(3) postperovskite structure, which was recently reported for pure MgSiO(3). The incorporation of Fe greatly reduces the pressure needed for the ...

π Ligands in Alkaline Earth Complexes

Thermal Properties of Alkaline Earth Oxides

The heat capacities of MgO, CaO, SrO and BaO, reported in part I have been analysed in terms of the frequency spectrum of the lattice with the assumption that the effect of anharmonicity of the lattice may be neglected for T (@D / 3 ) . Following the usual procedure the n-th moments of the frequency spectrum with n = — 3, —2, — 1, 0, 1 to 6 were calculated from the experimental data. From the l...