Current status and future directions for in situ transmission electron microscopy

Abstract

This review article discusses the current and future possibilities for the application of in situ transmission electron microscopy to reveal synthesis pathways and functional mechanisms in complex and nanoscale materials. The findings of a group of scientists, representing academia, government labs and private sector entities (predominantly commercial vendors) during a workshop, held at the Center for Nanoscale Science and Technology- National Institute of Science and Technology (CNST-NIST), are discussed. We provide a comprehensive review of the scientific needs and future instrument and technique developments required to meet them.

Keywords: DTEM; Direct electron detectors; ETEM; Gas/liquid-solid interactions; Heating holder; In situ TEM; Indentation holder; Liquid/gas cell holder; Phase transformation; Structure property relationship.

Figure 1

(a) External stimulii currently used for in situ observations on a TEM platform, (b) growth in number of publication during 1970 and 2012 (Sinclair, MRS Bull. (2013)) .

Figure 2

True stress versus true strain data for repeated loadings of an initially 133 nm diameter tensile sample in (100) orientation. The specimen yields at 636 MPa and shows significant hardening during elongation to 65 % true strain. Simultaneously, the dislocation density (defects can be seen as bright features in the upper row of dark field images) as denoted by the white diamond symbols and the right-hand axis of the graph is reduced by an order of magnitude. Correspondingly the deformation characteristics becomes more stochastic as the defect density decreases (Kiener et al., Nano Lett. (2011).

Figure 3

Dendrite growth and collapse during voltage cycle from lead nitride solution in a liquid cell (White et al., ACS Nano (2012).

Figure 4

An in situ TEM analysis of the amorphization of crystalline silicon triggered by electron irradiation. Systematic and quantitative data acquisition as a function of electron energy, dose and sample temperature (a) and (b) combined with a theoretical model predicting the volume of amorphous embryo that is created by the impact of an energetic electrons (c) and (d.

Figure 5

Contrast transfer functions for a 300 kV instrument with an objective lens gap width of 10 mm.

Figure 6

Loss of information limit can be estimated using fast Fourier transform (FFT) of amorphous carbon film (a) in vacuum and (b) in 1700 Pa of Ar. (c) Loss of intensity as a function of pressure for different gasses (Courtesy: Jakob Wagner)

Figure 7

(a) Number of participants using various instruments/techniques for in situ measurements and (b) area of improvement identified for successful experiments as needed to advance the state of the art.