To prepare a sample for the heat treatment in the SEM µReactor, the calcined fibers in the form of flakes were placed on the MEMS heating chip and rubbed on the surface by a micromanipulator. Using this method, several individual nanofibers were deposited on the heating stage area in the center of the MEMS chip. For all SEM image acquisitions, the acceleration voltage was set to 10 kV and the current to 0.4 nA. After preparing of the sample, heating was set up to 700 °C (heating rate 2 K s 1 ). Once the sample reached this temperature, the SEM was found to have lost focus. In order to renew the analysis, the imaging setting was brought to focus again, and the temperature was raised to 800 °C or more. The raster scan speed was variably set to 20.5 or 41 s per image. After the reaction ended, the magnification was reduced to see the whole set of fibers on the MEMS chip.