Articles written in Pramana – Journal of Physics

    • Structural, elastic and dynamical properties of ${\rm YP}_{1-x}{\rm As}_{x}$ alloys from first principles calculations


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      The structural, elastic and lattice vibration properties of the ternary alloys ${\rm YP}_{1-x}{\rm As}_{x}$ at various As concentrations ($x$) from 0 to 1, $x=0, 0.25 ,0.5, 0.75$ and 1, are presented. The calculations were performed using the density functional perturbation theory (DFPT) within the generalised gradient approximation (GGA) and employing virtual crystal approximation (VCA). We studied the effect of arsenic composition on structural parameters, the phase transition pressure, the elastic constants, the optical and acoustic phonon frequencies at high symmetry points $\Gamma$, $X$ and $L$, the static and electronic dielectric constants, and the Born effective charge. It is established that all these properties follow a quadratic law in the concentration ($x$). There is a good agreement between our results and the available data for binary compounds YP and YAs. Our results are predictions of ${\rm YP}_{1-x}{\rm As}_{x}$.

    • Theoretical prediction of lanthanum composition effects on structural, electronic and thermal properties of La$_x$Sc$_{1−x}$N alloys


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      In this study, we have explored the structural, electronic and thermal properties of La$_x$Sc$_{1−x}$N ternary alloys in rock-salt structure using the full-potential linearised augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). To calculate the exchange-correlation energy and potential, we have used the Wu–Cohen generalised gradient approximation and the modified Becke–Johnson. We investigated the effect of composition on lattice parameters, bulk modulus and band gap. The variation of the calculated lattice constant with lanthanum composition is practically linear and shows a small deviation of the obtained results from Vegard’s law. Moreover, the effect of thermal macroscopic properties was also investigated employing the quasiharmonic Debye model, which takes into account the lattice vibrations. We have found a good accord between our results, the experimental data and previous theoretical results available in the literature for the binary compounds which can be a support for the ternary alloys in the future.

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