High-pressure angle-dispersive X-ray diffraction study of mechanically alloyed SnSe2

Abstract

The effect of pressure on mechanically alloyed trigonal nanostructured SnSe2 (n-SnSe2) was studied by in situ angle-dispersive X-ray diffraction up to 25.8 GPa. The pressure dependence of lattice parameters and unit cell volume was investigated. By fitting the lattice parameters and unit cell volume to a third-order Birch–Murnaghan equation of state for several values of the applied pressure, the bulk modulus B0, its first derivative B′, and the linear moduli along the a- and c-axes were determined. The effect of pressure on the z coordinate of site 2d occupied by Se atoms was investigated using pair distribution function analysis. The results were compared with experimental and theoretical studies of SnS2 and SnSe2 reported in the literature.

Strategies and challenges of high-pressure methods applied to thermoelectric materials

“…A significant improvement in ZT under pressure has also been predicted for other common thermoelectric materials, namely, p-type SnSe 131 and n-type SnSe 2 . 132,133 The high-pressure phases of these chalcogenide semiconductors are not quenchable at ambient conditions, whereas local strains in their crystal lattices that simulate high-pressure effects may be generated in meso-or nanostructured samples or in composites prepared by HP-HT synthesis. For example, a high value of ZT = 0.88 at 473 K was estimated for an n-type (PbTe) 1−x (CoTe) x composite with x = 0.14, prepared by HP-HT synthesis at 6 GPa.…”

Self-limiting stoichiometry in SnSe thin films

“…It is thus more likely that the thickness fringes arise from a parasitic SnSe 2 layer in the film. Indeed, literature attributes the {001} hexagonal SnSe 2 orientations to both the peaks at 13.8° 44 and 16.6°, 45 labeled with the symbols and ✦, respectively. The appearance of parasitic SnSe 2 fingerprints in the XRD data point toward a relatively uncontrolled formation process that does not depend on the supplied Sn : Se flux ratio.…”

Electronic, vibrational, and electron-phonon coupling properties in SnSe$_2$ and SnS$_2$ under pressure

“…For instance, the lengths of the a and c axes at 10 GPa are reduced by about 3% and 11% with respect to their zeropressure values in both cases. As the pressure increases, the compressibility rate along the a axis becomes slightly smaller in SnS 2 than in SnSe 2 , following the expected trend that a more covalent intra-layer bond is less compressible 47 [see Supplemental Fig. S1 51 ].…”

“…Fig. 1(b)-(e) presents the optimized structural parameters as a function of pressure, together with available experimental data for comparison 19,28,[47][48][49][50] .…”