We have employed an effective interionic interaction potential approach to describe the
high-pressure phase transformation and mechanical properties of diluted magnetic semiconductors
Zn1−xMxSe
(M = Mn,Fe
and Cd). This potential consists of the long-range Coulomb and three-body
interactions (TBI) and the Hafemeister and Flygare type short-range overlap
repulsion extended up to the second neighbour ions and the van der Waals
(vdW) interaction. Our calculated results have revealed reasonably good
agreement with the available experimental data on the phase transition pressures
(Pt = 10,12,10 GPa) and the
elastic properties of Zn1−xMxSe. The equation of state curves (plotted between
V (P)/V (0)
and pressure) for both the zincblende (B3) and rocksalt (B1) structures obtained by us are in
fairly good agreement with the experimental results. The calculated values of the volume collapses
(ΔV (P)/V (0)) are also closer to the observed data. Further, the variations of the second- and third-order
elastic constants with pressure have followed a systematic trend, which are almost identical
to those exhibited by the observed data measured for other compounds of this family.
The temperature-dependent specific heat C[Formula: see text](T) of nanocrystalline (NC) Cu (8 nm) and Pd (6 nm) is theoretically analyzed and compared with the specific heat of their corresponding bulk materials in the temperature range from 150 K to 300 K. It is revealed that the C[Formula: see text] values of NC Cu (Pd) are about 10% (40%) higher as compared to that of their corresponding bulk form, the softening of phonon frequencies at interfaces in NC materials is argumented as the main mechanism responsible for enhancement in C[Formula: see text] in the present work. Lattice (phonon) specific heat is obtained following an overlap repulsive potential using Debye model. In NC materials having large interface volume ratio, the phonon frequencies and Debye temperature are comparatively less at the interfaces than at the core of nanocrystal. The contributions to specific heat due to atoms present at interfaces (C[Formula: see text]) and those present at the core of nanocrystal (C[Formula: see text]) are estimated separately by estimating the characteristic Debye temperature ([Formula: see text]) from elastic force constant ([Formula: see text]). The temperature derivative of the internal energy yields the electronic contribution to specific heat (C[Formula: see text]). The present investigation based on the softening of phonon frequencies mechanism is successful to explain the enhancement in specific heat by nanocrystallization.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.