  A new series of MAX family designated as 321 phases are recently reported
with Nb3As2C, V3As2C, Nb3P2C and Ta3P2C. Most of the physical properties of
these new MAX phase compounds are unexplored and the present study aims to
investigate their structural, elastic, thermal, and lattice dynamical
properties. Their mechanical and dynamical stabilities are examined. All the
phases are elastically anisotropic and brittle in nature. The Debye
temperatures and lattice thermal conductivities have been calculated. Lattice
dynamical features are investigated in detail and infrared and Raman modes are
identified. High melting temperature of these compounds are favorable for their
applications at elevated temperatures.
