Germanium Dioxide - Structure

Structure

The forms of germanium dioxide to an extent parallel those of silicon dioxide. Hexagonal GeO2 has the same structure as β-quartz (germanium having coordination number 4); tetragonal GeO2 (the mineral argutite) has the rutile-like structure of stishovite (germanium having coordination number 6); and amorphous (glassy) GeO2 is similar to fused silica.

Germanium dioxide can be prepared in both crystalline and amorphous forms. At ambient pressure the amorphous structure is formed by a network of GeO4 tetrahedra. At elevated pressure up to approximately 9 GPa the germanium average coordination number steadily increases from 4 to around 5 with a corresponding increase in the Ge-O bond distance. At higher pressures, up to approximately 15 GPa, the germanium coordination number increases to 6 and the dense network structure is composed of GeO6 octahedra. When the pressure is subsequently reduced, the structure reverts back to the tetrahedral form. At high pressure, the rutile form converts to an orthorhombic CaCl2 form.

Read more about this topic:  Germanium Dioxide

Famous quotes containing the word structure:

    Why does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.
    Paul Tillich (1886–1965)

    What is the structure of government that will best guard against the precipitate counsels and factious combinations for unjust purposes, without a sacrifice of the fundamental principle of republicanism?
    James Madison (1751–1836)

    A committee is organic rather than mechanical in its nature: it is not a structure but a plant. It takes root and grows, it flowers, wilts, and dies, scattering the seed from which other committees will bloom in their turn.
    C. Northcote Parkinson (1909–1993)