In situ observation and thermal alloying induced shape manipulation of FIB-grown Pt composite nanowires

• The driving force of the Pt nanowires deformation is studied in the in situ TEM.
• The generation of Pt-Ga alloy after heating is confirmed.
• The formation of Pt-Ga alloy causes the shear force which bends the nanowires.
• The alloy process should be considered seriously in the nanodevice application.

With the assistance of in situ heating techniques in the transmission electron microscope, the morphology change of the Pt nanowires which were deposited by focus ion beam has been monitored under different temperatures. With a drastic shape expansion, a significant bending has been observed abruptly above 250 °C. The energy dispersive X-ray spectroscopy mapping indicated the asymmetrical distribution of carbon (C), platinum (Pt) and gallium (Ga) within the Pt nanowires while the diffraction analysis revealed the crystalline formation of Ga-Pt alloys during the heating process. The in-situ exploration discovered that besides the recrystallization of Pt nanoparticles, the asymmetrical volume expansion from the Ga-Pt alloys formation should be another factor which induces the shape variation of the heated Pt nanowires.