Transmission electron goniometry and its relation to electron tomography for materials science applications

Abstract

Aspects of transmission electron goniometry are discussed. Combined with high resolution phase contrast transmission electron microscopy (HRTEM) and atomic resolution scanning TEM (STEM) in the atomic number contrast (Z-STEM) or the phase contrast bright field mode, transmission electron goniometry offers the opportunity to develop dedicated methods for the crystallographic characterization of nanocrystals in three dimensions. The relationship between transmission electron goniometry and electron tomography for materials science applications is briefly discussed. Internet based java applets that facilitate the application of transmission electron goniometry for cubic crystals with calibrated tilt-rotation and double-tilt specimen holders/goniometers are mentioned. The so called cubic-minimalistic tilt procedure for the determination of the lattice parameters of sub-stoichiometric WC1-x nanocrystals with halite structure is demonstrated. The freely (openly) accessible, Internet based, Crystallography Open Database (COD) is briefly discusses because the ability to determine the lattice parameters of nanocrystals opens up the possibility of identifying unknown phases by comparing these lattice constants to the entries of comprehensive databases. Correspondingly, a search of the determined lattice parameters in the COD is shown as part of a screen shot. The enhanced viability of transmission electron goniometry in TEMs (and STEMs) with aberration corrected electron optics is illustrated on the WC1-x model system.