Effects of laser wavelength and pulse energy on the evaporation behavior of TiN coatings in atom probe tomography: A multi-instrument study.

The impact of the laser wavelength on accuracy in elemental composition analysis in atom probe tomography (APT) was investigated. Three different commercial atom probe systems - LEAP 3000X HR, LEAP 5000 XR, and LEAP 6000 XR - were systematically compared for a TiN model coating studying the effect of shorter laser wavelengths, especially in the deep ultraviolet (DUV) range, on the evaporation behavior. The findings demonstrate that the use of shorter wavelengths enhances the accuracy in elemental composition, while maintaining similar electric field strengths.

AlO Grain Boundary Segregation in a Thermal Barrier Coating on a Ni-Based Superalloy.

The segregation of reactive elements (REs) along thermally grown oxide (TGO) grain boundaries has been associated to slower oxide growth kinetics and improved creep properties. However, the incorporation and diffusion of these elements into the TGO during oxidation of Ni alloys remains an open question. In this work, electron backscatter diffraction in transmission mode (t-EBSD) was used to investigate the microstructure of TGO within the thermal barrier coating on a Ni-based superalloy, and atom probe tomography (APT) was used to quantify the segregation behavior of REs to α-Al2O3 grain boundaries.

Beam broadening in transmission and conventional EBSD.

Transmission electron backscatter diffraction (t-EBSD) has become a routine technique for crystal orientation mapping when ultrahigh resolution is needed and has demonstrated advantages in the characterization of nanoscale and micron-sized samples (Babinsky et al., 2015). In this work, we use experimental measurements and simulations to compare the resolution of the transmission and conventional reflection EBSD techniques across a range of sample volumes and characterization conditions.

Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography.

There are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry.

Seed-mediated growth of shape-controlled wurtzite CdSe nanocrystals: platelets, cubes, and rods.

Prior investigations into the synthesis of colloidal CdSe nanocrystals with a wurtzite crystal structure (wz-CdSe) have given rise to well-developed methods for producing particles with anisotropic shapes such as rods, tetrapods, and wires; however, the synthesis of other shapes has proved challenging. Here we present a seed-mediated approach for the growth of colloidal, shape-controlled wz-CdSe nanoparticles with previously unobserved morphologies. The synthesis, which makes use of small (2-3 nm) wz-CdSe nanocrystals as nucleation sites for subsequent growth, can be tuned to selectively yield colloidal wz-CdSe nanocubes and hexagonal nanoplatelets in addition to nanorod and bullet-shaped particles.