M. A. Hadi

Structural, elastic, and electronic properties of recently discovered ternary silicide superconductor Li2IrSi3: An ab-initio study

The structural, elastic, and electronic properties of the very recently discovered ternary silicide superconductor, Li2IrSi3, have been calculated using ab-initio technique. We have carried out the plane-wave pseudopotential approach within the framework of the first-principles density functional theory (DFT) implemented within the CASTEP code. The calculated structural parameters show a reasonable agreement with the experimental results. Elastic moduli of this interesting material have been calculated for the first time. The electronic band structure and electronic energy density of states indicate the strong covalent Ir-Si and Si-Si bonding which lead to the formation of the rigid structure of Li2IrSi3. Strong covalency give rise to a high Debye temperature in this system. We have discussed the theoretical results in detail in this paper.

New ternary superconducting compound LaRu2As2: Physical properties from density functional theory calculations

In this paper, we have presented the density functional theory (DFT) based calculations performed within the first-principles pseudopotential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elastic constants ensure mechanical stability of the compound. The calculated Cauchy pressure, Pughs ratio as well as Poissons ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating (TBC) material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machineable because of its low hardness value of 6.8 Gpa. The multi-band nature is observed in calculated Fermi surface. A highly anisotropic combination of ionic, covalent, and metallic interactions is expected in accordance with charge density calculations.

First‐Principles Study of Superconducting ScRhP and ScIrP Pnictides

For the first time, we have reported in this study an ab initio investigation on elastic properties, Debye temperature, Mulliken population, Vickers hardness, and charge density of the two recently synthesized superconducting ScRhP and ScIrP pnictides. The optimized cell parameters show fair agreement with the experimental results. The mechanical stability of both ternary phosphides is confirmed via the calculated elastic constants. Both compounds are ductile in nature and damage tolerant. ScIrP is expected to be elastically more anisotropic than ScRhP. The estimated value of Debye temperature predicts that ScRhP is thermally more conductive than ScIrP and the phonon frequency in ScRhP is higher than that in ScIrP. Both pnictides are soft and easily machinable due to their low Vickers hardness. Moreover, the hardness of ScRhP is lower due to the presence of antibonding Rh-Rh in ScRhP. The metallic conductivity of ScRhP reduces significantly when Rh is replaced with Ir. The main contribution to the total density of states (TDOS) at Fermi-level (EF) comes from d-electrons of Sc and Rh/Ir in both pnictides. These two ternary compounds are characterized mainly by metallic and covalent bonding with little ionic contribution. The calculated superconducting transition temperatures fairly coincide with the reported measured values.

Intrinsic defect processes and elastic properties of Ti3AC2 (A = Al, Si, Ga, Ge, In, Sn) MAX phases

Mn+1AXn phases (M = early transition metal; A = group 13–16 element and X = C or N) have a combination of advantageous metallic and ceramic properties, and are being considered for structural applications particularly where high thermal conductivity and operating temperature are the primary drivers: for example in nuclear fuel cladding. Here, we employ density functional theory calculations to investigate the intrinsic defect processes and mechanical behaviour of a range of Ti3AC2 phases (A = Al, Si, Ga, Ge, In, Sn). Based on the intrinsic defect reaction, it is calculated that Ti3SnC2 is the more radiation-tolerant 312 MAX phase considered herein. In this material, the C Frenkel reaction is the lowest energy intrinsic defect mechanism with 5.50 eV. When considering the elastic properties of the aforementioned MAX phases, Ti3SiC2 is the hardest and Ti3SnC2 is the softest. All the MAX phases considered here are non-central force solids and brittle in nature. Ti3SiC2 is elastically more anisotropic and Ti3A...