Ab initio calculations for properties of MAX phases Ti2TlC, Zr2TlC, and Hf2TlC

Using ab initio calculations we have computed the lattice constants, bulk moduli, and local and total density of states of the MAX phases, Ti2TlC, Zr2TlC, and Hf2TlC in the hexagonal P6(3)/mmc space group. The results for lattice constants are within 2% of experimental results. The bulk moduli are predicted to be 125, 120, and 131 GPa, respectively. These are the lowest values of bulk moduli among all MAX phases studied to date. The electronic density of states shows that all three materials are conducting. These low values of their bulk moduli are attributed to weak metal M (M=Ti,Zr,Hf) bonding with the A element thallium. (c) 2006 American Institute of Physics.