Raman Spectroscopic Study of the Optical Phonons of Mg₂Si_1−xSn_x Solid Solutions

Abstract

Mg2Si1−xSnx solid solutions are prepared in the composition range from x = 0 to 1 by mechanical alloying using high‐energy ball milling followed by direct‐current sintering at 600–800 °C. X‐ray diffraction analysis confirms that the samples obtained are uniform solid solutions. Raman spectroscopy shows two first‐order phonon Raman bands and a distribution of Raman signals due to second‐order phonon Raman scattering. The first‐order Raman bands are assigned to the nondegenerate Raman‐forbidden F1u (LO) mode and the triply degenerate Raman‐allowed F2g mode. Both modes exhibit a linear shift of the phonon frequency with a composition showing a clear one‐mode behavior for this solid solution. The findings are discussed in the context of existing theories for the occurrence of the one‐mode or two‐mode behavior of phonons in solid solutions.

Density of States Effective Mass for p-Type Mg2Si–Mg2Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

“…However, they also found non-linearly varying lattice constants for the solid solutions in disagreement with all other calculations and experimental results (see e.g. [35][36][37] ). As band structure and lattice constant are closely related this might explain their surprising results.…”

Novel Non-Centrosymmetric NdSr4O(BO3)3 Borate and Nd(Ca1−xSrx)4O(BO3)3 Solid Solutions: Preparation, Crystal Structures, Thermal Expansion and Optical Properties

“…It was found that there is a decrease in the optical band gap when calcium is substituted by strontium ions (Figure 7a). This is consistent with the theory of the influence of the mass of substituting ions on the band gap [53].…”

“…In this case, with an increase in the Sr concentration, the position of both maxima shifts linearly towards low frequencies (Figure 6c). According to one of the theoretical models, the shift of the phonon band towards low frequencies can be associated with an increase in mass upon isovalent substitution in a solid solution [53]. For example, this shift is observed in Ca 3 (BO 3 ) 2 and Sr 3 (BO 3 ) 2 crystalline samples [54].…”

Influence of Mg loss on the phase stability in Mg2X (X = Si, Sn) and its correlation with coherency strain

“…However, we suppose that for 0.75 mole% Sb doping, the changes of the lattice constants are negligible in agreement with previous results in the literature (compare e.g. [46,47] with [48]). Also, the lattice constant reported in Table 3 for the as-pressed Mg2Si0.5Sn0.5 sample doped with 0.75 molar percent Sb (a = 6.559 Å) is very close to the lattice constant of the undoped Mg2-𝛿 Si0.5Sn0.5 obtained by Kato et al (a = 6.556 Å) [45].…”