Synthesis, physical properties and band structure of non-magnetic Y3AlC

Y3AlC has been synthesized by arc melting and subsequent annealing. Rietveld analysis of the powder x-ray diffraction (XRD) data confirms cubic Pm-3m structure. Electrical resistivity (rho) of Y3AlC exhibits metallic behaviour. No sign of superconductivity is observed down to the lowest measurement temperatures of 4.2 K in rho, and 2 K in magnetic susceptibility (chi) and specific heat (C-p) measurements. The value of the electronic specific heat coefficient gamma is 1.36 mJ/K-2 mol from which the density of states (DOS) at the Fermi energy (E-F) is obtained as 0.57 states/eV.unit cell. The value of Debye temperature theta(D) is estimated to be 315 K. Electronic band structure calculations of Y3AlC reveal a pseudo-gap in the DOS at E-F leading to a small value of 0.5 states/eV unit cell which matches quite well with that obtained from gamma. Non-zero value of the DOS indicates metallic behaviour as confirmed by our rho data. Covalent and ionic bonding seem to co-exist with metallic bonding in Y3AlC as indicated by van Arkel-Ketelaar triangle for Zintl-like systems. (C) 2016 Elsevier B.V. All rights reserved.