XANES and XPS studies of processes initiated by high-vacuum annealing in SnO$_x$/MWCNT composite layers

The initial and thermally treated composites based on SnO$_x$/MWCNT have been studied by the XANES and XPS methods using the equipment of the BESSY II Russian–German beamline of synchrotron radiation and by the AES and HRTEM methods. The characteristic mechanisms of chemical and structural transformations in the SnO$_x$ phase have been determined depending on the vacuum annealing temperature. It has been found that the basic process in the metal-oxide component at annealing temperatures not exceeding 500$^\circ$C is the tin monoxide SnO disproportionation reaction with the formation of the dioxide SnO$_2$ phase and metallic tin. An increase in the annealing temperature to 800$^\circ$C results in the activation of carbothermal reduction of metallic tin in contact areas of oxide clusters and MWCNT, as well as in the formation of nanocrystalline structures in the metal-oxide component of composite.