High temperature oxidation event of gelatin nanoskin-coated copper fine particles observed by in situ TEM

Metallic copper fine particles were prepared using CuO slurry by hydrazine reduction in the presence of gelatin. To observe a behavior of these particles at high temperature, in situ heating TEM observations were carried out. Oxygen gas was introduced and the pressure of the TEM column was kept at 10−3 Pa, corresponding the pressure around the sample at 10−1 Pa. The gelatin, which acts as a protective nanoskin on the particle surface was gradually decomposed. Around approximately 140 °C, it was observed that Cu2O dots formed on the surface of the copper particle. This result is well consistent with the behavior of the TG-DTA curve of the copper fine particles under ambient conditions, and provides key information of oxidative behavior of copper fine particles.