Full
Outline
The effects of heating temperature and duration time on the process of ZnO crystallization under the pressure of 5 GPa are studied systemically by the methods of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results show that the diffusion rate of ZnO increases greatly under high-pressure and the sample density higher than 99% of the theoretical value can be achieved after heated at 400 ℃ and 5 GPa for 0.5 h. With the increasing of the heating temperature, micro-cracks develop along crystal boundary in all samples, and eventually ZnO powder mixed with single crystals and poly-crystals forms above 500 ℃. The pale yellow crystallites with an average size of 100 μm and the largest size more than 350 μm was obtained at 850 ℃ after heating of 5 min. The sample morphology analysis shows that the reason for the ultra fast crystallization of ZnO under high-pressure is possibly caused by a very quick diffusion rate of ZnO along certain direction. The crystal boundary along such direction moves very quickly under high-pressure until the neighboring micro-crystals merge into a single crystal in a short time, while the micro-crystals shrink in the other direction and cause micro-cracks along other crystal boundaries.
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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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