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Outline
With nanometer SiO2 powder as initial material, the p-T phase diagram (2.0~4.2 GPa, 150~1 200 ℃) of α-quartz and coesite was obtained by a series of experiments under high pressure and high temperature, and the slope of the boundary in the phase diagram is negative below 650 ℃ and is basically horizontal above 650 ℃. By means of transmission electron microscopy (TEM), X-ray diffractometer (XRD), Raman spectrometry (Raman), fourier transform infrared spectrometry (FT-IR), thermogravimetry and differential thermal analysis measurements (TG-DTA), the phenomenon that the water in the nanometer SiO2 can decrease the synthesis temperature of coesite and quicken reaction velocity was found, and the nanometer SiO2 can be crystallized into coesite under 4.2 GPa and 190 ℃, which is much lower than the synthesis temperatures of coesite that have been reported. Under ambient pressure, the coesite synthesized from nanometer SiO2 can stably exist at 800 ℃ and is transformed into cristobalite above 1 000 ℃.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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