The structure of amorphous, crystalline and liquid GeO₂

Abstract

Abstract. Germanium dioxide (GeO 2 ) is a chemical analogue of SiO 2 . Furthermore, it is also to some extent a structural analogue, as the low and high-pressure short-range order (tetrahedral and octahedral) is the same. However, a number of differences exist. For example, the GeO 2 phase diagram exhibits a smaller number of polymorphs, and all three GeO 2 phases (crystalline, glass, liquid) have an increased sensitivity to pressure, undergoing pressure induced changes at much lower pressures than their equivalent SiO 2 analogues. In addition, differences exist in GeO 2 glass in the medium range order, resulting in the glass transition temperature of germania being much lower than for silica. This review highlights the structure of amorphous GeO 2 by different experimental (e.g., Raman and NMR spectroscopy, neutron and x-ray diffraction) and theoretical methods (e.g., classical molecular dynamics, ab initio calculations). It also addresses the structure of liquid and crystalline GeO 2 that have received much less attention. Furthermore, we compare and contrast the structural differences between GeO 2 and SiO 2 , as well as, along the GeO 2 − SiO 2 join. It is probably a very timely review as interest in this compound, that can be investigated in the liquid state at relatively low temperatures and pressures, continues to increase.

Preparation of hexagonal GeO2particles with particle size and crystallinity controlled by peptides, silk and silk-peptide chimeras

“…Bis-tris propane (1,(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) Bis(tris(hydroxymethyl)methylamino)propane,99%) was obtained from Acros Chemicals. Chemicals were used as received.…”

Atomic structure of a metal-supported two-dimensional germania film

“…For vitreous bulk materials, direct experimental information on atomic coordinates is not available [4]. There is a discussion in the literature that germania in comparison to silica will have different properties, in particular with respect to the formation of vitreous, i.e., glassy, phases [5][6][7]. Also, doping of germanium into silica or a mixed phase of both might lead to promising materials in a number of applications [8][9][10][11].…”

Comparative classical and ‘ab initio’ molecular dynamics study of molten and glassy germanium dioxide

“…Now, the question arises whether this is also true for the other prototype of a "strong glassformer", namely GeO 2 . While molten silica has been studied extensively, both by various experimental techniques and by computer simulations [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34], studies of molten and glassy germanium dioxide are less abundant, and this holds true for both experiments [35,36,37,38,39,40,41,42,43,44,45,46] and simulations [47,48,49,50,51,52,53,54,55].…”