Grain evolution of nano-crystals ZnO under HP and HT
Tóm tắt
Grain evolution of nano-crystals ZnO under high temperature and pressure is studied using a cubic high pressure apparatus. The structure, grain sizes and morphology of the samples are characterized by X-ray diffraction and field emission scanning electron microscopy. The results show that the grain sizes of ZnO grow rapidly at temperature 200°C under pressure. At temperature lower than 300°C (including 300°C), the grain sizes of the samples first increase with the pressure increasing from 1 to 3 GPa and later decrease from 4 to 6 GPa. The activation volume from 1 to 3 GPa and from 4 to 6 GPa is calculated respectively using the phenomenological kinetic grain growth equation at temperature 300°C. At temperature higher than 400°C (including 400°C), the grain sizes of the samples increase with the pressure increasing from 1 to 6 GPa. ZnO nano-bulks with good quality can be obtained under the specific conditions.
Tài liệu tham khảo
Ahuja R, Fast L, Eriksson O. Elastic and high pressure properties of ZnO. J Appl Phys, 1998, 83: 8065–8067
Desgreniers S. High-density phases of ZnO: Structural and compressive parameters. Phys Rev B, 1998, 58: 14102–14106
Decremps F, Julio P P, Saitta A M. High-pressure raman spectroscopy study of wurtzite ZnO. Phys Rev B, 2002, 65: 92101–92104
Wu Z Y, Cao L, Bao X Z. The properties and structural investigation of ZnO nanocrystals under pressure. Chinese Journal of High Pressure Physics (in Chinese), 2003, 17: 45–49
Jiang J Z, Olsen J S, Gerward L. Phase transformation of nanocrystalline ZnO under high-pressure. Europhys Lett, 2000, 50: 48–54
Yuan W Z, Tian W, Guo J. Sintering of ZrO2(4Y) nanocrystals under high pressure. Chinese Journal of High Pressure Physics, 2001, 15: 259–264
Wickham J N, Herhold A B, Alivisatos A P. Shape change as an indicator of mechanism in the high-pressure structural transformation. Phys Rev Lett, 2000, 84: 923–927
Li Y L, Liang Y, Zheng F. Ultrahigh pressure sintering of nano-amorphous Si3N4 powders at low temperature. Chinese Journal of Materials Research, 1997, 11: 473–478
Blanco M A, Recio J M, Costales A. Transition path for the B3-B1 phase transformation in semiconductors. Phys Rev B, 2000, 62: 599–602
Qin X J, Shao G J, Li H, Chen Y, Chen M Z. Preparation and characteristic of ZnO nano-powderswith a good quality. Journal of Yanshan University (in Chinese), 2002, 17: 236–238
Lu G Q, Nygren E, Aziz M J, Turnbull D. Pressure-enhanced solid phase epitaxy of germanium. Appl Phys Lett, 1990, 56(2): 137–139
Mayo M J. High and low temperature superplasticity in nanocrystalline materials. NanoStructured Materials, 1997, 9: 717–726
Nahm C W, Ryu J S. Influence of sintering temperature on varistor characteristics of ZPCCE-based ceramics. Mater Lett, 2002, 53: 110–115
Jiang J Z, Gerward L, Olsen J S. Phase transformation of nanocrystalline ZnS under high-pressure. Scripta Mater, 2001, 44: 1983–1988
Jaffe J E, Snyder J A, Lin Z. LDA and GGA calculations for high-pressure phase transtion in ZnO and MgO. Phys Rev B, 2000, 62(3): 1660–1665
Recio J M, Blanco M A, Luana V. Compressibility of high pressure rocksalt phase of ZnO. Phys Rev B, 1998, 58: 8949–8954
Sui Y, Zheng F L, Xu D P. Influence of the pressure on defect and structure in composite oxide nano-solid. Chinese Journal of High Pressure Physics (in Chinese), 1997, 4: 245–248
Shao G J, Qin X J, Liu R P, Wang W K. Grains fining and properties of nanocrystals ZnO under high pressure. Acta Phys Sin (in Chinese), 2006, 55(1): 472–476