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

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• 作者：S.S. Ghule^a ; C.S. Garde^b ; ^{gardecs@gmail.com" class="auth_mail" title="E-mail the corresponding author} ; S. Ramakrishnan^c ; S. Singh^d ; A.K. Rajarajan^e ; Meena Laad^f
• 关键词：Electrical resistivity ; Magnetic susceptibility ; Specific heat ; Band structure calculations ; Carbide
• 刊名：Physica B: Physics of Condensed Matter
• 出版年：2016
• 出版时间：1 October 2016
• 年：2016
• 卷：498
• 期：Complete
• 页码：98-103
• 全文大小：1123 K

文摘

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 (ρ) of Y₃AlC exhibits metallic behaviour. No sign of superconductivity is observed down to the lowest measurement temperatures of 4.2 K in ρ, and 2 K in magnetic susceptibility (χ) and specific heat (C_p) measurements. The value of the electronic specific heat coefficient γ is 1.36 mJ/K² 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 θ_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 γ. Non-zero value of the DOS indicates metallic behaviour as confirmed by our ρ 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.