Transition metal silicide surface grafting by multiple functional groups and green optimization by mechanochemistry

Abstract

The functionalization by different coupling agents enabled to modify the properties of the surface of CrSi2 nanocrystallites.

Anharmonicity and Effect of the Nanostructuring on the Lattice Dynamics of CrSi2

“…Its chemical composition, determined by EPMA, is highly homogeneous with a stoichiometry determined to be CrSi 1.96 with silicon vacancies. The refined lattice parameters a = 4.435(2) Å and c = 6.374 (6) Å are in good agreement with those determined in our previous study (a = 4.431 (7) A ̊and c = 6.365(5) A ̊). 4 All the peaks of the XRD patterns of the S1, S2, and S3 samples, shown in Figure 2a, are attributed to the CrSi 2 phase, evidencing their phase-pure character within the detection limits associated with this technique.…”

“…However, their thermal conductivity remains about one order of magnitude larger than that of PbTe (about 10–15 W/m K at room temperature), which strongly limits their thermoelectric performance. Thus, CrSi 2 -based alloys (P6 2 22 space group) may become promising candidates for thermoelectric applications if their lattice thermal conductivity could be significantly lowered by alloying, nanostructuring, or a combination of both. − In this regard, we recently investigated the effect of nanostructuring on the lattice thermal conductivity of CrSi 2 by mechanical ball milling and demonstrated that decreasing the grain size to 45 nm reduces λ l by a factor of ∼2 . Not only does this effect originate from an increase in the phonon scattering at the grain boundaries but also to an increase in the point-defect concentration that further scatters the propagating acoustic phonons.…”

Effect of the Deposition Time and Heating Temperature on the Structure of Chromium Silicides Synthesized by Pack Cementation Process

“…This can be explained by the high diffusivity of Cr in the nanostructure and the active formation of a Cr-rich oxide layer [48,49]. According to the literature [50], the oxidation rate of CrSi 2 is determined by the diffusion of all the reaction components at lower temperatures (700-900 • C), whereas it is mainly controlled by the diffusion of chromium over cationic vacancies in the p-type Cr 2 O 3 lattice at higher temperatures. of CrSi2 is determined by the diffusion of all the reaction components at lower temperatures (700-900 °C), whereas it is mainly controlled by the diffusion of chromium over cationic vacancies in the p-type Cr2O3 lattice at higher temperatures.…”