Infrared and Raman spectra of Bi2O2X and Bi2OX2 (X = S, Se, and Te) studied from first principles calculations

Xu, Yao; Lv, Yang‐Yang; Chen, Y. B.; Yao, Shu‐Hua; Zhou, Jian

doi:10.1039/c9ra02584g

Cited by 29 publications

(28 citation statements)

References 56 publications

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“…Similar structural relaxation was observed earlier also in chemical vapor deposition (CVD) grown Bi 2 O 2 Se nanosheets . Theoretical analysis of Γ point phonon modes of Bi 2 O 2 Se yields four Raman active modes: A 1g and B 1g modes corresponding to the out of plane vibration of Bi and O atoms, respectively, and E g 1 and E g 2 modes corresponding to the in-plane vibration of Bi and O atoms, respectively. − Previous studies indicate that out of these four Raman active modes, only the A 1g mode is observable in the backscattering configuration. ,, Figure S5 exhibits the room temperature Raman spectra of the Bi 2 O 2 Se nanosheets in which the A 1g mode is evident around ∼151.9 cm –1 . A comparison between the Raman spectra of bulk and nanosheet Bi 2 O 2 Se samples indicates a low-energy shift of the A 1g mode in the nanosheet (Figure S5) due to phonon softening, corresponding to weakened interlayer coupling in the ultrathin nanosheets …”

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confidence: 69%

Ultrathin Free-Standing Nanosheets of Bi₂O₂Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

et al. 2019

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S2 MethodsReagents. Bismuth nitrate (Bi(NO3)35H2O, Alfa Aesar, 99.9%), selenourea (SeC(NH2)2, Alfa Aesar, 99.9%), potassium hydroxide (KOH, S D Fine-Chem Limited (SDFCL)), sodium hydroxide (NaOH, SDFCL), Disodium EDTA (C10H14O8Na2N2H2O, SDFCL) and ethanol were used without any further purification.Synthesis procedure. 100 mg (0.206 mmol) of Bi(NO3)35H2O, 12.7 mg (0.103 mmol) of SeC(NH2)2 and 306.8 mg (0.824 mmol) of disodium EDTA were sequentially added at a 5 minutes interval into 20 ml water in a glass beaker. The solution was stirred continuously. The addition of Bi(NO3)35H2O into water results in a milky white color solution which turns into an orange color solution after the addition of SeC(NH2)2. The solution becomes clear after the addition of disodium EDTA. Finally, 120 mg (2.14 mmol) of KOH and 320 mg (8 mmol) of NaOH were added into the solution which turns the solution color black. After 10 minutes of stirring, the solution was put to rest which results in precipitation of the dark brown color nanosheets. We observed that nanosheets of similar morphology and thickness can also be obtained without using disodium EDTA, however, in that case, the required amount of water solvent is much higher, 200 ml. These were then washed with alcohol and water and centrifuged to remove disodium EDTA. The purified product was then dried in a vacuum oven at 150 C.Step I: In water, Bi(NO3)3 undergoes hydrolysis to produce BiONO3 and the process of hydrolysis is expedites in alkaline medium:Step II: Selenourea SeC(NH2)2 undergoes decomposition in alkaline medium to generate selenide ions (Se 2-) along with cyanamide (H2NCN): SeC(NH2)2 + OH -→ Se 2-+ H2NCN + H2O

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confidence: 69%

Ultrathin Free-Standing Nanosheets of Bi₂O₂Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

et al. 2019

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“…In order to further verify the pressure-induced formation of Bi–S bonding experimentally, we collected in situ Raman spectra during compression and decompression (Figures S9 and S10 and detailed discussion in the Supporting Information). All Raman-active vibrations come from the Bi–O layers, without contributions from S atoms. , Under high pressures, a new Raman peak appears at around 225 cm –1 at 11.8 GPa, which comes from the vibrations of the Bi–S bonding . This finding further confirms the formation of Bi–S bonding and the disappearance of LPEs.…”

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confidence: 58%

Pressure-Regulated Dynamic Stereochemical Role of Lone-Pair Electrons in Layered Bi₂O₂S

Luo

Guo

et al. 2020

J. Phys. Chem. Lett.

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Lone-pair electrons (LPEs) ns2 in subvalent 14 and 15 groups lead to highly anharmonic lattice and strong distortion polarization, which are responsible for the groups’ outstanding thermoelectric and optoelectronic properties. However, their dynamic stereochemical role in structural and physical properties is still unclear. Here, by introducing pressure to tune the behavior of LPEs, we systematically investigate the lone-pair stereochemical role in a Bi2O2S. The gradually suppressed LPEs during compression show a nonlinear repulsive electrostatic force, resulting in two anisotropic structural transitions. An orthorhombic-to-tetragonal phase transition happens at 6.4 GPa, caused by the dynamic cation centering. This structural transformation effectively modulates the optoelectronic properties. Further compression beyond 13.2 GPa induces a 2D-to-3D structural transition due to the disappearance of the Bi-6s2 LPEs. Therefore, the pressure-induced LPE reconfiguration dominates these anomalous variations of lattice, electronic, and optical properties. Our findings provide new insights into the materials optimization by regulating the characters of LPEs.

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“…The band centered at 123 cm −1 could be from the A 1 g mode of the Bi 2 OTe 2 semiconductor. [ 52–55 ] Since the SNAB host glass matrix is composed of a considerable amount of oxygen, it is possible that during the annealing process some O 2− bound itself to the Bi 3+ /Te 2− ions, thereby forming Bi 2 OTe 2 .…”

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confidence: 99%

Study of vibrational properties of Bi_2 − xMn_xTe₃ nanocrystals in host glass: Effect of xMn‐concentration

Silva

Guimarães

Cano

et al. 2021

J Raman Spectroscopy

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The Raman and infrared (IR) active lattice vibrations of xMn‐concentration Bi2 − xMnxTe3 nanocrystals (NCs) as a dopant in semiconductor Bi2Te3 nanocrystals grown in a host glass matrix, whose symmetries correspond to the Rtrue3¯m−D3d5 space group, are investigated by Raman scattering. Transmission electron microscopy images confirm the formation of Bi2 − xMnxTe3 nanocrystals with an average size of around 5.4 nm. The observation of the six hyperfine structure lines in electron paramagnetic resonance spectra confirms the incorporation of Mn2+ ions in Bi2Te3 nanocrystals. The vibrational modes of quintuple layer (QL) of the diluted magnetic semiconductor Bi2 − xMnxTe3 nanocrystals are modified in relation to pure Bi2Te3 nanocrystals. The appearance of the A2u1 (95.5 cm−1), A2u2 (114 cm−1), and Eu2 (103 cm−1) IR‐active modes is mainly due to quantum size effects. Indeed, the redshifts of the A2u1 (95.5 cm−1), 0.25emEu2 (103 cm−1), Eg2 (110 cm−1), A2u2 (114 cm−1), and A1g2 (141 cm−1) vibrational modes give strong indications of the substitutional and interstitial incorporation of Mn2+ in the Bi2Te3 crystalline structure. In addition, the Raman spectra show the formation of Bi2OTe2 semiconductor due to the appearance of the (123 cm−1) mode. The investigation of the Bi2 − xMnxTe3 nanocrystal has promising potential to design new devices with magnetic and optical properties adjusted according to the xMn‐concentration.

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Infrared and Raman spectra of Bi₂O₂X and Bi₂OX₂ (X = S, Se, and Te) studied from first principles calculations

Abstract: Crystal structures of bismuth oxychalcogenide compounds Bi2O2X and Bi2OX2 (X = S, Se, and Te).

Cited by 29 publications

References 56 publications

Ultrathin Free-Standing Nanosheets of Bi₂O₂Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Ultrathin Free-Standing Nanosheets of Bi₂O₂Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Pressure-Regulated Dynamic Stereochemical Role of Lone-Pair Electrons in Layered Bi₂O₂S

Study of vibrational properties of Bi_2 − xMn_xTe₃ nanocrystals in host glass: Effect of xMn‐concentration

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Infrared and Raman spectra of Bi2O2X and Bi2OX2 (X = S, Se, and Te) studied from first principles calculations

Abstract: Crystal structures of bismuth oxychalcogenide compounds Bi2O2X and Bi2OX2 (X = S, Se, and Te).

Cited by 29 publications

References 56 publications

Ultrathin Free-Standing Nanosheets of Bi2O2Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Ultrathin Free-Standing Nanosheets of Bi2O2Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Pressure-Regulated Dynamic Stereochemical Role of Lone-Pair Electrons in Layered Bi2O2S

Study of vibrational properties of Bi2 − xMnxTe3 nanocrystals in host glass: Effect of xMn‐concentration

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Infrared and Raman spectra of Bi₂O₂X and Bi₂OX₂ (X = S, Se, and Te) studied from first principles calculations

Ultrathin Free-Standing Nanosheets of Bi₂O₂Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Ultrathin Free-Standing Nanosheets of Bi₂O₂Se: Room Temperature Ferroelectricity in Self-Assembled Charged Layered Heterostructure

Pressure-Regulated Dynamic Stereochemical Role of Lone-Pair Electrons in Layered Bi₂O₂S

Study of vibrational properties of Bi_2 − xMn_xTe₃ nanocrystals in host glass: Effect of xMn‐concentration