A Complete Solid Solution with Rutile‐Type Structure in SiO₂–GeO₂ System at 12 GPa and 1600°C

Abstract

High pressure and temperature synthesis of compositions made of (Si1−x,Gex)O2 where x is equal to 0, 0.1, 0.2, 0.5, 0.7, and 1 was performed at 7–12 GPa and 1200–1600°C using a Kawai‐type high‐pressure apparatus. At 12 GPa and 1600°C, all the run products were composed of a single phase with a rutile structure. The lattice constants increase linearly with the germanium content (x), which indicates that the rutile‐type phases in the SiO2–GeO2 system form a complete series of solid solutions at these pressure and temperature conditions. Our experimental results show that thermodynamic equilibrium state was achieved in this system at 12 GPa and 1600°C, but not at 1200°C. At lower pressures (7 and 9 GPa) and 1600°C, we observed the decomposition of (Si0.5,Ge0.5)O2 into SiO2‐rich coesite and GeO2‐rich rutile phases. The silicon content in the rutile structure increases sharply with pressure in the vicinity of the coesite–stishovite phase transition pressure in SiO2.

Persistent Octahedral Coordination in Amorphous GeO2 Up to 100 GPa by Kβ′′Spiekermann1, Harder2, Gilmore3 et al. 2019Phys. Rev. X202250View full textAdd to dashboardCite

“…We loaded amorphous GeO 2 (a-GeO 2 [47]) (three independent loadings), polycrystalline quartzlike GeO 2 (q-GeO 2 ) (two independent loadings), and rutilelike GeO 2 (r-GeO 2 , [48]) (one loading) into diamond anvil cells (DACs). r-GeO 2 was measured at high pressure as a reference material of CN ¼ 6.…”

Key melt properties for controlled synthesis of glass beads by aerodynamic levitation coupled to laser heating

“…Although numerous studies also reported the ADL synthesis and characterization of silicate or borate glasses and melts (for instance, [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] ) the strong volatility of some chemical components [48][49][50] (e.g., B 2 O 3 and alkali oxides) under laser irradiation still represents a major drawback of ADL-driven materials discovery, limiting its applicability within these chemical domains. Borate and silicate glasses can be easily prepared by conventional melt-quenching, but ADL was recently shown to provide a superior approach to elucidate transition metal saturation and homogenous nucleation in aluminosilicate glasses and glass-ceramics, [51][52][53] again taking advantage of the high melting temperatures, fast cooling rates and suppression of heterogeneous surface nucleation.…”