Structure, morphology and electrical transport properties of the Ti3AlC2 materials

摘要

A study of Ti3AlC2 materials prepared with Self Propagating High-Temperature Synthesis (SHS) method followed by uniaxial hot pressing (HP) is presented. Three groups of materials have been synthesized from different substrates using pure element and/or intermetallic powders. The SHS prepared powders and dense HP materials were characterized with x-ray diffraction and were found to contain more than 80% of the Ti3AlC2 MAX phase with anisotropic distribution of the crystallographic directions of its crystallites with respect to the HP pressure axis. This is accompanied with different mean size of the crystallites. The measured temperature dependencies of the electrical resistivity are consistent with those reported in the literature but show a higher R(300 K)/R(4 K) ratio of 3.5. They also exhibit slightly different values of thermal coefficient and residual resistivity between the materials studied. The magnetoresistance at 4 K and 300 K, investigated up to 35 kOe applied field, revealed a quadratic field dependence. The corresponding values of the electronic carrier density are found to be of 30% larger at 4 K than at 300 K and different between the materials studied. The results are discussed with respect to the Local Density of States calculations and compared with the resistivity and magnetoresistance data for others materials, like copper, and aluminum.