J.J. Fundenberger

Polycrystal orientation maps from TEM

Determination of topography of crystallite orientations is an important technique of investigation of polycrystalline materials. A system for creating orientation maps using transmission electron microscope (TEM) Kikuchi patterns and Convergent beam electron diffraction patterns is presented. The orientation maps are obtained using a step-by-step beam scan on a computer-controlled TEM equipped with a CCD camera. At each step, acquired diffraction patterns are indexed and orientations are determined. Although, the approach used is similar to that applied in SEM/electron back scattered diffraction (EBSD) orientation imaging setups, the TEM-based system considerably differs from its SEM counterpart. The main differences appear due to specific features of TEM and SEM diffraction patterns. Also, the resulting maps are not equivalent. On these generated by TEM, the accuracy of orientation determination can be better than 0.1 degrees. The spatial resolution is estimated to be about 10nm. The latter feature makes the TEM orientation mapping system an important tool for studies at fine scale unreachable by SEM/EBSD systems. The automatic orientation mapping is expected to be a useful complement of the conventional TEM contrast images. The new technique will be essential for characterization of fine structure materials. To illustrate that, example maps of an aluminum sample produced by severe plastic deformation are included.

Growth and characterization of c-axis inclined AlN films for shear wave devices

This paper reports on the growth and the characterization of c-axis inclined AlN thin films synthesized at low temperature. These films are of significant interest for shear wave generation in the shear mode resonators that operate as a liquid sensor. AlN films were deposited on 3 inch (1 0 0) silicon wafers using an RF-magnetron sputtering planar system. A SiO2 buffer layer was used to promote the c-axis inclination. This c-axis inclination of AlN thin films was investigated using scanning electronic microscopy and x-ray diffraction in θ/2θ, χ and rocking curve scan modes. These analyses showed up to 10° of c-axis inclination in our planar charging system at low temperature. An AlN film thickness variation of about ±5% was recorded. In this study, we only presented the effect of the pressure on the c-axis inclination of AlN films. A discussion about the effect of this parameter and the role of the SiO2 buffer layer is reported. A shear mode acoustic wave device based on the deposited c-axis inclined AlN film was constructed and showed a phase velocity of 5832 m s−1. This value of shear velocity is discussed.

Using EBSD and TEM-Kikuchi patterns to study local crystallography at the domain boundaries of lead zirconate titanate

Reliable EBSD mapping of 90° domains in a tetragonal ferroelectric perovskite has been achieved for the first time, together with reliable automated orientation determination from TEM‐Kikuchi patterns. This has been used to determine misorientation angles at 90° domain boundaries and thus local c/a ratios. The sources of orientation noise/error and their effects on the misorientation angle data have been thoroughly analyzed and it is found that this gives a cosine distribution of misorientation angles about the mean with a characteristic width related to the width of the orientation noise distribution. In most cases, a good agreement is found between local c/a ratios and global measurements by X‐ray diffraction, but some clear discrepancies have also been found suggesting that real local variations are present, perhaps as a consequence of compositional inhomogeneities.

Study of global and local crystallography at the domain boundaries of lead zirconate titanate piezoelectric ceramics

Reliable automated orientation mapping of 90° domains in a tetragonal perovskite has been achieved for the first time using both EBSD and TEM-Kikuchi pattern analysis. This has been used to compare local measurements of c/a ratios in PZT with global measurements by X-ray diffraction. The local c/a rations are in broad agreement with the global measurements, but further work is needed to determine whether the small discrepancies are real local variations or are caused by experimental factors.