In this paper we report on a systematic investigation, in the $5\text{to}300\mathrm{K}$ temperature regime, of the electronic, magnetotransport, thermoelectric, thermal, and elastic properties of four $M_2\mathrm{Al}\mathrm{C}$ phases: ${\mathrm{Ti}}_2\mathrm{Al}\mathrm{C}$, ${\mathrm{V}}_2\mathrm{Al}\mathrm{C}$, ${\mathrm{Cr}}_2\mathrm{Al}\mathrm{C}$, and ${\mathrm{Nb}}_2\mathrm{Al}\mathrm{C}$. The electrical conductivity, Hall coefficient, and magnetoresistances are analyzed within a two-band framework assuming a temperature-independent charge carrier concentration. As with other $MAX$-phase materials, these ternaries are nearly compensated, viz. the densities and mobilities of electrons and holes are almost equal. There is little correlation between the Seebeck and Hall coefficients. With Young’s and shear moduli in the $270\mathrm{GPa}$ and $120\mathrm{GPa}$ range, respectively, the phases studied herein are reasonably stiff. With room temperature thermal conductivities in the $25\mathrm{W}∕\mathrm{m}\mathrm{K}$ range ($45\mathrm{W}∕\mathrm{m}\mathrm{K}$ for ${\mathrm{V}}_2\mathrm{Al}\mathrm{C}$) they are also good thermal conductors.

• Received 1 April 2005

DOI:https://doi.org/10.1103/PhysRevB.72.115120