Understanding the structural and chemical characteristics of composite materials at the atomic scale—particularly at their internal interfaces—is crucial for the design and optimization of composite‑based devices with tailored functional, mechanical, and thermal properties. With recent advances in (scanning) transmission electron microscopy ((S)TEM), new pathways for highly precise structural and chemical analysis have become accessible, enabling broad applicability across diverse composite material systems, including metal–matrix composites, ceramic–ceramic interfaces, polymer‑based hybrid materials, and complex multilayer architectures.

This contribution highlights novel developments, which readily enable sub-atomic scale characterization and flexible analytical capabilities. With high-performance cold field‑emission sources of modern TEMs in combination with energy dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS), precise quantification of chemical gradients, defect structures, and bonding variations in oxide, carbide, and nitride interfaces are readily accessible. These capabilities are demonstrated by the analysis of the distribution of chemical state of carbon atoms at the periphery of (modified) carbon fibres. Recent advances also include an electron dose modulator (EDM) [1], which periodically blanks the beam at nanosecond-fast speed and controllable on-off-rates, enabling to investigate beam-sensitive materials, such as hybrid organic-inorganic materials or nanoparticle-reinforced composites with beam-sensitive matrix material. Furthermore, state-of-the-art STEM detector technology extends the analytical capabilities by capturing convergent beam electron diffraction (CBED) patterns at high speeds for each pixel of the scan image [2]. This results in four-dimensional STEM data which enables the analysis of local crystal phases as well as strain, electric field and magnetic field distributions. In this context, the novel JEOL 4D Canvas detector with a central hole is presented and utilised for the simultaneous investigation of crystal orientation and chemical analysis by EELS. In addition, the application of ultra-fast scanning coils for the acquisition of in-situ STEM experiments are shown. STEM in-situ experiments have so far been limited by typical pixel times in the microsecond range. With the novel ultra-fast scanning coils, pixel times in the nanosecond range are possible, which therefore enable the in-situ analysis of the performance and change of materials (e.g. catalysts) under external influences at TV frame rates. This is demonstrated by ultra-fast STEM studies of the diffusion of Pt atoms on a support material surface.
 
[1] https://www.jeol.com/products/scientific/tem/EDM.php
[2] https://www.jeol.com/words/emterms/20250826.php#gsc.tab=0