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摘要: 将10 nm钛酸钡粉在6 GPa超高压条件下进行烧结,得到了晶粒大小约为30 nm的钛酸钡陶瓷。用扫描电子显微镜和原子力显微镜观测了样品的微观结构。研究表明,由于超高压能够压碎纳米粉体中的团聚体,而且能增加烧结的驱动力,降低成核的势垒,从而使成核速率增加;同时由于扩散能力的降低而使生长速率减小,所以超高压烧结能在较低的温度和较短的时间内得到致密的纳米陶瓷。用压电力显微镜对样品的压电性能进行了检测。在30 nm钛酸钡陶瓷的不同区域内,都存在完整的压电响应回线,说明在30 nm钛酸钡陶瓷中存在压电性。此外,由于超高压的还原性气氛,使钛酸钡陶瓷在烧结过程中产生了氧空位,氧空位俘获电子而形成F+色心,使钛酸钡陶瓷颜色变黑。Abstract: 10 nm raw BaTiO3 powder was sintered by ultra-high pressure assisted method at 6 GPa. The grain size of sintering samples is about 30 nm. The microstructures of sintering samples were studied by scanning electron microscope and atomic force microscopy. The results indicated that owing to the ultra-high pressure, the agglomerates in nano powders were broken down, and the densification was significantly increased. Additionally, the nucleation rate was increased due to reducing the energy barrier for nucleation and the growth rate was reduced due to the decrease of diffusivity. Thus, ultra-high pressure enables the specimen to be fabricated under relatively lower temperature and shorter period that assures to obtain dense nanocrystalline ceramics. The piezoelectricity was investigated by piezoelectric force microscopy. There existed some full piezoresponse hysteresis loops at different areas in 30 nm BaTiO3 ceramics, indicating the presence of piezoelectricity. In addition, oxygen vacancies were produced in strongly reducing atmosphere during ultra-high pressure sintering. F+ centers were formed because oxygen vacancies caught electrons, and therefore, the color of BaTiO3 ceramics became block.
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Key words:
- BaTiO3 /
- ultra-high pressure sintering /
- nanocrystalline ceramics /
- piezoeletricity /
- color center
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Skandan G. Processing of Nanostructured Zirconia Ceramics [J]. Nanostruct Mater, 1995, 5(2): 111-126. Chaim R, Margulis M. Densification Maps for Spark Plasma Sintering of Nanocrystalline MgO Ceramics [J]. Mater Sci Eng A, 2005, 407: 180-187. Zhao Z, Buscagila V, Viviani M, et al. Grain-Size Effects on the Ferroelectric Behavior of Dense Nanocrystalline BaTiO3 Ceramics [J]. Phys Rev B, 2004, 70: 024107(1)-024107(10). Chen I W, Wang X H. Sintering Dense Nanocrystalline Oxide without Final Stage Grain Growth [J]. Nature, 2000, 404: 168-171. Wang X H, Deng X Y, Bai H L, et al. Two-Step Sintering of Ceramics with Constant Grain-Size, Ⅱ: BaTiO3 and Ni-Cu-Zn Ferrite [J]. J Am Ceram Soc, 2006, 89(2): 438-443. Liao S C, Chen Y J, Kear B H, et al. High Pressure/Low Temperature Sintering of Nanocrystalline Alumina [J]. Nanostruct Mater, 1998, 10(6): 1063-1079. Yuan W Z, Tian W, Guo J. Rapid Sintering of Nanocrystalline ZrO2(4Y) Powder under High Pressure [J]. Chinese Journal of High Pressure Physics, 2001, 15(4): 259-264. (in Chinese) 袁望治, 田卫, 郭捷, 等. 纳米ZrO2(4Y) 的快速高压烧结研究 [J]. 高压物理学报, 2001, 15(4): 259-264. Li B R, Wang X H, Li L T. Synthesis and Sintering Behavior of BaTiO3 Prepared by Different Chemical Methods [J]. Mater Chem Phys, 2002, 78: 292-296. Xiao C J, Jin C Q, Wang X H. Crystal Structure of Dense Nanocrystalline BaTiO3 Ceramics [J]. Mater Chem Phys, 2008, 111: 209-212. Buscaglia M T, Viviani M, Buscaglia V, et al. High Dielectric Constant and Frozen Macroscopic Polarization in Dense Nanocrystalline BaTiO3 Ceramics [J]. Phys Rev B, 2006, 73: 064114(1)-064114(10). Wang X H, Deng X Y, Wen H, et al. Bulk Dense Nanocrystalline BaTiO3 Ceramics Prepared by Novel Pressureless Two-Step Sintering Method [J]. Appl Phys Lett, 2006, 89: 162902(1)-162902(3). Xiao C J, Chi Z H, Zhang W W, et al. The Phase Transitions and Ferroelectric Behavior of Dense Nanocrystalline BaTiO3 Ceramics Fabricated by Pressure Assisted Sintering [J]. J Phys Chem Sol, 2007, 68: 311-314. Kim I D, Avrahami Y, Harry L T. Study of Orientation Effect on Nanoscale Polarization in BaTiO3 Thin Films Using Piezoresponse Force Microscopy [J]. Appl Phys Lett, 2005, 86: 192907(1)-192907(3). Xiao C J, Jin C Q, Wang X H. The Fabrication of Nanocrystalline BaTiO3 Ceramics under High Temperature and High Pressure [J]. Mater Process Technol, 2009, 209(4): 2033-2037.
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