Full
SHEN Xingmei (1982-), female, Ph.D., Associate Professor. E-mail: xxxxmx@126.com
Outline
Nb2O5 has a variety of crystalline states. However, the intermediate process of forming a long-range ordered structure is still unclear. Nb2O5 precursor was prepared by a sol-gel method. The intermediate-state samples in the crystallization of amorphous Nb2O5 were obtained at 460 ℃-520 ℃. The crystal structure, morphology, pore structure and crystallization kinetics of the intermediate-state samples were investigated. The results show that the atomic ordering process of the sample is from 1.0 nm short-range order with an amorphous state, to 1.0 nm short-range order with a small amount of crystal and amorphous mixed state, to 1.5 nm medium-range order with a pseudo hexagonal and amorphous mixed state, and then to more than 2.0 nm long-range order with a pseudo hexagonal, orthorhombic and a small amount of amorphous mixed state. The crystallinity of the samples at >495 ℃ increases rapidly from 20% to 86%. The samples are formed due to the crisscross accumulation of massive flaky particles and a small amount of rod-shaped particles. From a short-range order to a long-range order, the growth process of flake particles is the main process, while the rod-shaped particles have little change. The particles are mesoporous, and the size of the main pore becomes 10 nm as the calcination temperature increases. The Avrami index (n) of the samples is 1-2, and the main nucleation mode is the surface nucleation. During the transformation from short program to medium program, there exists a crystallization incubation period. This study provides a working basis for the investigation of Nb2O5 crystallization intermediate state.
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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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