Raman Spectra of Bismuth Oxyhalide Single Crystals

Abstract

Oxyhalogenides of bismuth BiOX (X=Cl, Br and I) are very interesting materials which nd various applications as X-ray luminescent screens, anti-Stokes (frequency upshift) converters, luminophors, and photoconducting analyzers of linear polarized radiation. Since each primitive cell consist of six monoatomic sites, the structure of the reduced representation of the 15 normal modes of vibration is: Γ = 2A1g(Ra.) + B1g(Ra.) + 3Eg(Ra.) + 2A2u(i.r.) + 2Eu(i.r.), in which the vibrations of A1g, B1g and Eg species are active in the Raman spectrum and those of A2u and Eu species are active in the infrared (i.r.) spectrum. The Raman active modes are observed in frequency range 55 225 cm −1 , 50 185 cm −1 , and 45 175 cm −1 for the BiOCl, BiOBr and BiOI single crystals respectively.

Effective removal of phenol by activated charcoal/BiOCl composite under UV light irradiation

“…These Raman spectral results are consistent with other previous reports [16], [17]. In case of samples containing AC, the bands reflecting sp 2 carbon atoms called D and G bands were also present around 1300-1700 cm -1 , however, their intensity varied with change in the amount, as shown in the inset of…”

Electronic Structures and Lattice Dynamics of Layered BiOCl Single Crystals

“…While our density functional theory (DFT) calculations give the opposite result, we assign modes around 60 and 200 cm –1 as E g and A 1 g modes, respectively. Our assignment agrees with both Bunda’s report based on polarized Raman study of BiOCl single crystals and Rulmont’s report based on the different extinction phenomena between the doubly degenerate E g mode and symmetrical A 1 g and B 1 g modes . Consistently, the recent DFT calculations and Raman measurements of similar BiOBr single crystals also assign the lowest energy mode at 57 cm –1 to the E g mode …”

Atomically Thin Oxyhalide Solar‐Blind Photodetectors

“…As shown in Figure 1g, the peak at ≈145 cm −1 is attributed to the A 1g stretching mode of BiOCl crystals. [ 25 ] With increasing thickness, the frequencies of A 1g mode reveal a blueshift (stiffen) trend from 144.5 cm −1 (3.8 nm) to 145.9 cm −1 (29.8 nm), which may because the increased interlayer vdW forces suppress the vibration of atoms. [ 22 ] The uniform square shape of Raman mapping image at 145 cm −1 indicates a high crystallization quality of BiOCl flakes (Figure 1h).…”