Photoemission and x-ray-absorption study of boron carbide and its surface thermal stability

We present a photoemission and x-ray-absorption study on boron carbide which identifies the spectroscopic features of this material, discussing them in connection with current structural models. A study on the surface thermal stability is also performed, revealing that despite the high melting point of boron carbide (~2600K), significant surface modifications occur in the material at about 1800 K. At this temperature the surface becomes covered with a graphite layer formed from bulk segregation of carbon, leaving boron-rich boron carbide buried beneath the graphitic surface.