On the pressure-dependent phonon characteristics and anomalous thermal expansion coefficient of 3C-SiC

Pressure and temperature stability boundaries of cubic SiC polymorphs: a first-principles investigation

“…Softening has been observed or predicted for the B3 phase for the modes and points TA(L), 52 LA(L) 52 and TA(X). 39,48 In our results, softening is predicted at 0 GPa in TA(L) and in both TA(L) and TA(X) at higher pressures. For LA(L), our values are clearly nonnegative in the range studied.…”

“…Our α value for 3C–SiC–B3 at zero pressure and 300 K (8.15 × 10 −6 K −1 ) is close to the experimental value 27,38 and previous computations. 27,39 The value of α reduces with pressure at a progressively decreasing rate (in the absolute value) with estimated average derivative values of −2.14 × 10 −7 K −1 GPa −1 between 0 and 5 GPa and −0.97 × 10 −7 K −1 GPa −1 between 0 and 65 GPa. We notice that the accurately determined α value of Si at room T (7.71 × 10 −6 K −1 13 ) is already reached by 3C–SiC–B3 at around 2 GPa according to our calculations.…”

“…For the B3 phase, our results for TO(G) and LO(G) are in agreement with previous calculations and experimental results. 37,39,[46][47][48][49][50][51][52][53] The only experimental results available outside the G point are from Wang et al, 52 which were obtained using the data of Olego et al 46,47 but assuming the own Wang et al theoretically calculated bulk modulus. The overall agreement we found with respect to the experimental results (except for LA(L)) provides support to our data outside those ranges that are not available in other calculations and experiments.…”

Interfacial thermal resonance in an SiC–SiC nanogap with various atomic surface terminations

“…57 That is, in addition to acoustic phonons, even optical phonons can contribute to heat transfer across the SiC-SiC nanogap. [58][59][60][61] For the nonidentical cases of C-Si and Si-C, the VDOSs of the atomic terminated layer in the heating wall are mismatched with those in the cooling wall, as shown in Fig. 5(a) and (b).…”

“…57 That is, in addition to acoustic phonons, even optical phonons can contribute to heat transfer across the SiC–SiC nanogap. 58–61…”