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Surface diffusion study of single crystal and bicrystal ceramics by AFM

AFM 单晶和双晶陶瓷的表面扩散研究

基本信息

批准号：
08650788
负责人：
IKUMA Yasuro
金额：
$ 1.47万
依托单位：
Kanagawa Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

项目摘要

One group of the samples used in this study was bicrystal MgO which was made with (100) surface and grain boundary tilted 24^0 in [010] direction. After examining by AFM,the samples were heated at 1100-1400ﾟC and reexamined by AFM.The grain boundary width (w) is proportional to t^<1/4>, where t is the annealing time, implying that surface diffusion controls the process. It was found that AFM made it possible to study grain boundary grooving at lower temperatures and short annealing time. The surface diffusion coefficient determined in this way was in good agreement with the data in the literature determined by interference microscope.Using photoetching technique and subsequent annealing, sinusoidal profile was formed on (100) plane surface of MgO single crystals. The sinusoidal profile decay was then studied on these specimens. The diffusion coefficients calculated from the results were several orders of magnitude faster than the results obtained by grain boundary grooving. This suggests that mechanism is different in these two processes.Bicrystal SrTiO_3 with the same orientation as bicrystal MgO was also studied. Contrary to MgO the cross section of the surface of SrTiO_3 after the formation of groove was exactly the same as that predicted by Mullins. It was also observed in the measurement that grain boundary grooving in SrTiO_3 was controlled surface diffusion. This was supported by the measurement of groove height, h. Since h can not be measured by interference microscope, the measurement of his unique to AFM.The surface diffusion in SrTiO_3 determined by grain boundary grooving is almost in the same range as the oxygen lattice diffusion in SrTiO_3 but is faster than Sr lattice diffusion. Although the diffusion coeffcient of Ti in SrTiO_3 is not known, the present result is the surface diffusion of slower moving cation.

本研究中使用的一组样品是双晶氧化镁，它是由(100)面和晶界沿[010]方向倾斜24^0制备的。样品经原子力显微镜检验后，在1100-1400ﾟ℃加热，并用原子力显微镜复查，晶界宽度(W)与t^&lt；1/4&gt；成正比，其中t是退火时间，这表明表面扩散控制了这一过程。研究发现，原子力显微镜可以在较低的温度和较短的退火时间下研究晶界沟槽。用这种方法测得的表面扩散系数与文献中用干涉显微镜测得的数据吻合得很好。利用光刻技术和随后的热处理，在氧化镁单晶的(100)面表面形成了正弦轮廓。然后对这些试件的正弦轮廓衰减进行了研究。由结果计算的扩散系数比用晶界刻槽得到的结果快几个数量级。这表明在这两个过程中机理是不同的。还研究了与双晶MgO具有相同取向的双晶SrTiO3。与氧化镁相反，钛酸锶形成凹槽后的表面截面积与Mullins的预测完全相同。在测量中还观察到，SrTiO3中的晶界沟槽是由表面扩散控制的。由于h不能用干涉显微镜测量，因此Hs的测量是原子力显微镜所特有的。由晶界刻槽确定的SrTiO3中的表面扩散与SrTiO3中的氧晶格扩散几乎在同一范围内，但比锶晶格扩散快。虽然钛在SrTiO_3中的扩散系数未知，但目前的结果是较慢运动的阳离子的表面扩散。