~Raman spectra characterization of boron carbide using first-principles calculations

The influence of pressure on the Raman spectra of (B11C)CBCp crystal is studied using first-principles calculations. The calculated spectra agree well with the reported experimental spectra. Reported spectra of recovered samples after depressurization amorphization show activity near similar to 1340 cm(-1), similar to 1520 cm(-1), and similar to 1810 cm(-1). Corresponding phonon modes are identified in the spectra calculated at 100 GPa. These activities are consistently present even at lower pressures up to 0 GPa and is shown to be essential due to the monoclinic symmetry of the polar structure. However, the Raman activity corresponding to the similar to 1810 cm(-1) phonon was not reported up to 50 GPa during pressurization due to its low intensity. The changes in the Raman activity with the pressure are related to the changes in the polarization. The amorphization induced high pressure in the surrounding crystalline region is responsible for the experimentally observed activities in recovered samples after depressurization amorphization.

Automated summary

The influence of pressure on the Raman spectra of (B11C)CBCp crystal was studied using first-principles calculations. The results showed that the changes in the spectra were closely related to the polar structure of the crystal and were responsible for the observed activities after amorphization. Studying these changes can provide insights into the relationship between the crystal structure and properties.