Optical properties of Ti3SiC2 and Ti4AlN3

The dielectric functions of the MAX phases, Ti3SiC2 and Ti4AlN3, have been determined from first principles calculations. We compared the dielectric functions and the reflectivity spectra of Ti3SiC2 and Ti4AlN3 with those of TiC and TiN. The optical spectra were analyzed by means of the electronic structure, which provides theoretical understanding of the conduction mechanism of these two phases. We found that Ti4AlN3 can be used to avoid solar heating and also increase the radiative cooling due to the increased thermal emittance as compared to TiN. Ti4AlN3 can therefore be a candidate coating material for temperature control of space vehicles. (C) 2008 American Institute of Physics.