(b) A schematic drawing of the rhombohedral unit cell. The shaded plane is the (001) plane. Within the plane, orange lines represent the three in-zone directions: HM781-36B mouse [100], [010], and , along which

planar defects can be observed. Blue lines represent the three off-zone directions: [001], , and , from which the planar defects cannot be seen. (c) A roadmap consisting of simulated diffraction patterns of major low index zone axes within the (001) plane. During TEM examination, the roadmap helps the operator to determine whether it is possible to tilt to the desired zone axes. A roadmap consisting of simulated diffraction patterns of major low index zone axes within the (001) plane is shown in Figure 2c. During TEM examination, this roadmap can help us judge if it is possible to tilt to the next zone axis according to the calculated angle between different zone axes. For example, it is nearly impossible to obtain results from both and [010] zone axes on the same nanowire because the calculated inter-axial angle (57.1°) is close to the tilting limit of our TEM specimen holder (60°). In the roadmap, there are four independent patterns such as those from , , [010], and [110] directions, as grouped in four colors. During TEM examination, planar defects can be seen along directions

of , , and [010] whose diffraction patterns are asymmetric and with streaks in them. While AICAR research buy viewing along the [110] direction, BAY 80-6946 ic50 the layered faults feature is hidden because of the mirror symmetry. In addition, planar defects are more distinctive when viewing along directions of and [010] than that of (see Additional file 1 for comparison between experimental results obtained from the aforementioned four different zone axes). Therefore, in our real TEM practice, only results from the two independent directions: and [010] are recorded and analyzed. There are a total of six equivalent -type and [010]-type Megestrol Acetate directions in the rhombohedral system, as drawn in orange and blue lines in Figure 2b. Characteristic features of planar defects can be observed by TEM when the viewing direction is along the rhombohedral axes or the short

diagonal within the (001) plane, i.e., the directions of [100], [010], and . These three directions (outlined in orange) are denoted as in-zone directions. Meanwhile, the other three directions: [001], , and , located out of the (001) plane (marked in blue), are denoted as off-zone directions, due to the fact that planar defects are invisible from them. Now the difficulty to visualize planar defects in boron carbide nanowires becomes obvious. If the viewing direction is not parallel to planar defects, the defects will be invisible. In addition, even if the viewing direction is parallel to planar defects, depending on the initial orientation of the viewing direction, planar defects may also not be observed. For example, if the initial viewing direction (i.e.