Silicon carbide

Spectroscopy

Quantum mechanics

Transmission electron microscopy

Crystal (programming language)

Stacking fault

Materials science

High-resolution transmission electron microscopy

Thermal conductivity

Scattering

Electron energy loss spectroscopy

Phonon

Thermal diffusivity

Computer science

Physics

Nanotechnology

Optics

Molecular physics

Condensed matter physics

Composite material

Chemistry

Programming language

Dislocation

Nature

Crystal defects affect the thermal and heat-transport properties of materials by scattering phonons and modifying phonon spectra1-8. To appreciate how imperfections in solids influence thermal conductivity and diffusivity, it is thus essential to understand phonon-defect interactions. Sophisticated theories are available to explore such interactions, but experimental validation is limited because most phonon-detecting spectroscopic methods do not reach the high spatial resolution needed to resolve local vibrational spectra near individual defects. Here we demonstrate that space- and angle-resolved vibrational spectroscopy in a transmission electron microscope makes it possible to map the vibrational spectra of individual crystal defects. We detect a red shift of several millielectronvolts in the energy of acoustic vibration modes near a single stacking fault in cubic silicon carbide, together with substantial changes in their intensity, and find that these changes are confined to within a few nanometres of the stacking fault. These observations illustrate that the capabilities of a state-of-the-art transmission electron microscope open the door to the direct mapping of phonon propagation around defects, which is expected to provide useful guidance for engineering the thermal properties of materials.

Single-defect phonons imaged by electron microscopy