AFM图像库：Cypher快速扫描

重复点缺陷

溶剂退火嵌段共聚物

For these investigations, the sample was be electrically connected to a sample holder in the Cypher AFM including the optional High Voltage Amplifier (http://www.asylumresearch.com/Products/CypherOptions/CypherOptions.shtml). The HV-PFM option enables high sensitivity, high bias, and crosstalk-free measurements on piezoelectrics, including ferroelectrics and multiferroics. The cantilever was an Arrow UHF the was custom coated with a Pt film, making it electrically conductive.In this example, a short (~0.5 second) -100 Volt DC pulse was applied to the sample. This pulse distorted the domain boundary in the middle of the image. After applying the negative pulse, we applied a gradually increasing positive bias, starting from zero and ending at 30 V. This was sufficient to restore the domain to a state very close to the original. 

Astute observers will notice that the amplitude is not the same on either side of the domain boundary and in fact this asymmetry increases with the bias. We attribute this effect to the (undesirable) electrostatic bias effect as discussed in Kalinin and Bonnell, Physical Review B, Volume 65, 125408 (2002) and other references.

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铌酸锂高速PFM

在云母上松散地结合DNA

方解石上的点缺陷

Some interesting physics is visible in the movie. As the steps retreat, they get pinned, or hung up, on several defects. Just as the surface tension of a three-dimensional soap bubble acts to minimize its area, the step edges have a line tension that acts to minimize their length. The line tension combines with the pinning and sublimation to determine the curved shape of the step in two dimensions. As the crystal continues to sublimate, a pinned step bows out farther until it breaks free of the defect and races across the terrace.

The defects persist as many steps pass across them, so they must extend down perpendicular to the crystal face, into the body of the crystal. Because no step edges terminate at the defects, they do not appear to be screw dislocations. They may be edge dislocations with a Burgers vector in the plane of the image. Note that in images 999 to 1003, near the image center, a defect moves to the right and then disappears. It may have joined with an adjacent defect. Then, in image 1153, a defect (possibly the same one) becomes visible another 300 nm to the right. The sublimation of the crystal is exposing, layer-by-layer, the three-dimensional arrangement of the defects.

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空气中的蒽烷烃