Geometric, electronic and elastic properties of dental silver amalgam γ-(Ag3Sn), γ1-(Ag2Hg3), γ2-(Sn8Hg) phases, comparison of experiment and theory

Mechanical and electronic properties of Ag3Sn intermetallic compound in lead free solders using ab initio atomistic calculation

“…2, we see that C 11 / = C 22 / = C 33 which is true for orthorhombic crystal. The computed value of elastic stiffness constants are close to that calculated by Davies et al [23] using GGA functional. As already mentioned, the values of elastic stiffness constants calculated by Lee et al [22] using GGA functional involves 'theory mixing' (LDA + GGA) so it is slightly overestimated as compared to our result.…”

“…Thus, the first-principles computation in present work is sufficiently reliable to reproduce the equilibrium crystal structure of Ag 3 Sn. In addition, the computed lattice parameters are very close (less than 0.6% difference) to result of Davies et al [23] when GGA USPs under GGA functional is used. It can be seen from Table 2 that use of LDA ultrasoft pseudopotential results in contraction of optimized cell volume relative to experiment.…”

“…So, to improve its mechanical durability, it is important to calculate elastic anisotropy. Lee et al [22] and Davies et al [23] calculated the structural and elastic properties of Ag 3 Sn using DFT but there is need to study the elastic anisotropy both quantitatively by calculating various anisotropic indices and qualitatively. These authors attributed the scatter in experimental data of Young's modulus of Ag 3 Sn to the elastic anisotropy but the actual quantitative data regarding anisotropy of Young's modulus which could completely explain the different experimental results is lacking.…”

Poisson's ratio and modern materials

“…In the case of crystalline structures, the valence electron density plays a key role, and ab-initio calculation is becoming an increasingly popular approach following the early work of Cohen 27 . Subsequently, the cases of diamond semiconductors (ν Si = 0.22 and ν Ge = 0.28) were reported 28 , as were the fullerites 29 , molybdenum 40 and most recently dental amalgams 41 . There are, however, isolated cases where the interpretation is not straightforward.…”

Poisson's ratio over two centuries: challenging hypotheses

“…The connection between the sensible forces at insensible distances started to be re-established with atomistic computer simulation; 26 in the past few years, by employing ab initio quantum mechanical methods, elastic constants have been accurately predicted, 73 including Poisson's ratio. 74 By contrast, in experimental science, much of the novelty in revisiting Poisson's ratio has come through the discovery of new materials whose functionality relates to length scales larger than atomistic and to which continuum mechanics applies, affirming what Roderick Lakes has argued since 1987: that 'the classical theory of elasticity has no length scale.' 29,75 Poisson's ratio therefore applies to architectural frameworks just as it does to colloids, for example, or to the atomic architecture of the mechanically active components that all materials are constructed from.…”