TY - JOUR

T1 - Insights into high-pressure stability, vibrational and mechanical characteristics of Ba5(BO3)3F

AU - Sagatov, Nursultan

AU - Bekker, Tatyana B.

AU - Mikhno, Anastasiya O.

AU - Davydov, Alexey V.

N1 - This work was supported by the Russian Science Foundation, grant № 24–19–00252, https://www.rscf.ru/project/24–19-00252/. We thank the Information Technology Centre of Novosibirsk State University for providing access to the cluster computational resources. This work was performed using equipment supported by the state assignment of Sobolev Institute of Geology and Mineralogy SB RAS of the Ministry of Science and Higher Education of the Russian Federation (FWZN-2026-0014).

PY - 2026/4

Y1 - 2026/4

N2 - The fluoroborate Ba5(BO3)3F, a candidate for UV optical applications, is investigated through density functional theory (DFT) and experimental methods to unravel its electronic, vibrational, mechanical characteristics and high-pressure stability limit. DFT calculations with HSE06 functional reveal a direct band gap of 5.46 eV, corroborating experimental transparency in the mid-UV range. Phonon dispersion analysis confirms dynamic stability, and the simulated Raman spectrum are in good agreement with the obtained experimental data, enabling the detailed assignment of 23 observed modes. The two most intense peaks at 902 and 909 cm–1 attributed to symmetric stretching vibrations of two crystallographically different [BO3] groups in the structure. The Ba5(BO3)3F compounds exhibits strong elastic anisotropy, with bulk modulus (B) varying by a factor of 2.7 (38.7–104.7 GPa) across crystallographic directions. The estimated Vickers hardness (2.68 GPa) and fracture toughness (0.556 MPa·m1/2) of Ba5(BO3)3F classify it as mechanically soft yet more crack-resistant than, for instance, β-BaB2O4. High-pressure calculations reveal that Ba5(BO3)3F is stable up to 9 GPa under hydrostatic compression, beyond which shear instability (C44 − P < 0) and soft phonon modes occur.

AB - The fluoroborate Ba5(BO3)3F, a candidate for UV optical applications, is investigated through density functional theory (DFT) and experimental methods to unravel its electronic, vibrational, mechanical characteristics and high-pressure stability limit. DFT calculations with HSE06 functional reveal a direct band gap of 5.46 eV, corroborating experimental transparency in the mid-UV range. Phonon dispersion analysis confirms dynamic stability, and the simulated Raman spectrum are in good agreement with the obtained experimental data, enabling the detailed assignment of 23 observed modes. The two most intense peaks at 902 and 909 cm–1 attributed to symmetric stretching vibrations of two crystallographically different [BO3] groups in the structure. The Ba5(BO3)3F compounds exhibits strong elastic anisotropy, with bulk modulus (B) varying by a factor of 2.7 (38.7–104.7 GPa) across crystallographic directions. The estimated Vickers hardness (2.68 GPa) and fracture toughness (0.556 MPa·m1/2) of Ba5(BO3)3F classify it as mechanically soft yet more crack-resistant than, for instance, β-BaB2O4. High-pressure calculations reveal that Ba5(BO3)3F is stable up to 9 GPa under hydrostatic compression, beyond which shear instability (C44 − P < 0) and soft phonon modes occur.

KW - Band structure

KW - Borates

KW - Density functional theory

KW - High pressure

KW - Mechanical properties

KW - Raman spectra

UR - https://www.scopus.com/pages/publications/105029310494

UR - https://www.mendeley.com/catalogue/2aa2ef20-eab8-3bf2-83d5-fa3c416c0580/

U2 - 10.1016/j.nxmate.2026.101680

DO - 10.1016/j.nxmate.2026.101680

M3 - Article

VL - 11

JO - Next Materials

JF - Next Materials

SN - 2949-8228

M1 - 101680

ER -