Mobile oxygens make silicate magma flow.Silicon, that marvelous material at the core of glasses, ceramics, sand, computer chips, even magma spewing from volcanoes, has revealed yet another side of its versatile nature to scientists studying its properties. Researchers knew that silicon-oxygen compounds, called silicates, consist of tetrahedral tet·ra·he·dral adj. 1. Of or relating to a tetrahedron. 2. Having four faces. tet formations, in which four oxygen atoms surround each silicon. But sometimes, silicon forms a brief relationship with a fifth oxygen atom, geologist Jonathan F. Stebbins from Stanford University reports in the June 20 NATURE. Using nuclear magnetic resonance nuclear magnetic resonance: see magnetic resonance. nuclear magnetic resonance (NMR) Selective absorption of very high-frequency radio waves by certain atomic nuclei subjected to a strong stationary magnetic field. , he has demonstrated the existence of the anomalous silicon in a liquid silicate silicate, chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, calcium, iron, magnesium, manganese, potassium, sodium, or zirconium. Silicates may be considered chemically as salts of the various silicic acids. . He and others think the overcrowded o·ver·crowd v. o·ver·crowd·ed, o·ver·crowd·ing, o·ver·crowds v.tr. To cause to be excessively crowded: a system of consolidation that only overcrowded the classrooms. silicon plays a key role in making this liquid flow. "It's basically a defect and it increases the rate at which things move around," says Frank J. Spera, a geologist at the University of California, Santa Barbara History The predecessor to UCSB, Santa Barbara State College, focused on teacher training, industrial arts, home economics, and foreign languages. Intense lobbying by an interest group in the City of Santa Barbara led by Thomas Storke and Pearl Chase persuaded the State , who studies the molecular dynamics of silicates. "A small concentration can be enough of a disruption [to the liquid's structure] to produce important changes: It breaks down the viscosity of a fluid." The viscosity of silicon-based magma influences volcanic eruptions volcanic eruptions discharging of fumes, dust and lava from volcanoes. They have damaging potential in addition to those of being physically overpowering by the lava flow or the ash or dust fallout. . While less viscous magma flows, thicker magmas tend to trap gases inside where they "build up like a pressure cooker" until the volcano explodes, says Ian Farnan, a Stanford chemist working with Stebbins. An understanding of the dynamics of the magmas may enable geologists to better assess how violent an eruption will be, he adds. Theorists had predicted the existence of five- and higher-fold coordinate silicons, which represent intermediate, denser phases of silicate. These would allow an oxygen to shift from one silicon partner to another and consequently enable the liquid to flow. "It's moving closer at the same time that another [oxygen] is moving slightly further away," says Farnan. The researchers caught the oxygen in this dance by rapid cooling, or quenching quenching Rapid cooling, as by immersion in oil or water, of a metal object from the high temperature at which it is shaped. Quenching is usually done to maintain mechanical properties that would be lost with slow cooling. , liquid silicate, thereby causing the atoms to freeze in their places. |
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