Raman spectroscopy of the BC₃ phase obtained under high pressure and high temperature

Abstract

A direct transformation of the g-BC 3 phase to a new diamond-like d-BC 3 phase was observed in a diamond-anvil cell (DAC) at high temperature, 2033 ± 241 K, and high pressure, 50 GPa. Analysis of the peak positions of the d-BC 3 , B 4 C, a-boron, and the boron-doped diamond leads to the conclusion that the positions of the peaks of the d-BC 3 are more similar to the peak pattern of the boron-doped diamond rather than that of boron carbide, a-boron.

Phase transition in BCx system under high-pressure and high-temperature: Synthesis of cubic dense BC3 nanostructured phase

“…1b), which supports the occurrence of a phase transition. It displays a broad peak at 420 cm -1 , a second peak at 1188 cm -Raman spectrum of the c-BC 3 is similar to that measured previously 17 where tentative assignment was discussed. Analysis of the Raman spectra of the diamond-like phases, BC x phases, and those of boron carbide (α-boron) shows that the most intense peaks, 1085 cm -1 in B 4.3 C and 795 cm -1 in α-boron, are not seen in the Raman spectra of the c-BC 3 17 .…”

“…The HPHT conditions of the transition of the graphitic BC x phase to another phase are also disputable: phase transitions were detected above 35 GPa in Refs. [16][17][18]21 ; and was not observed in the BC x system (1.6 < x ≤ 3) at pressures of 20 GPa 15 , 19 GPa 17 , and 24 GPa (Ref. 16 and this study).…”

“…Analysis of the Raman spectra of the diamond-like phases, BC x phases, and those of boron carbide (α-boron) shows that the most intense peaks, 1085 cm -1 in B 4.3 C and 795 cm -1 in α-boron, are not seen in the Raman spectra of the c-BC 3 17 . The most intense peak at 420 cm -1 can be attributed to the Raman active stretching modes of B-B dimers 17,21 . The second most intense peak at 1188 cm -1 may have the same origin as the 1211 cm -1 peak of the c-BC 1.6 phase and the 1231 cm -1 peak of the dl-BC 3 phase 17 .…”

“…The most intense peak at 420 cm -1 can be attributed to the Raman active stretching modes of B-B dimers 17,21 . The second most intense peak at 1188 cm -1 may have the same origin as the 1211 cm -1 peak of the c-BC 1.6 phase and the 1231 cm -1 peak of the dl-BC 3 phase 17 . The Raman mode centered around 1200 cm -1 was detected in heavily boron-doped polycrystalline diamond films 41 .…”

“…Recently, researchers claimed to observe a phase transition from graphitic phase to dl-BC 5 at 24 GPa and temperature of 2200 K, in a BC 5 system 19 . Despite progress in the understanding of the phase transition in BC x materials, such as observations of the phase transitions in BC 1.6 , BC 3 , and BC 5 under high pressure and high temperature [15][16][17][18][19][20][21] , we still do not know many important properties of the obtained phases (e.g.…”