LIQUID CRYSTALS
·
2024
·
IF 2.4
Xin Zhang,Deyuan Yao,Xiaomei Pan,Erqiao Xue,Peng Cheng,Tingting Ye,Junfeng Ding
The crystal structures of liquid crystals, particularly various oligomers, have garnered significant attention, laying the groundwork for developing new materials and devices. Here, we demonstrate pressure plays a crucial role in the structure of liquid crystals. High-pressure Raman and photoluminescence spectra were on 5CB (4-cyano-4’−pentylbiphenyl) liquid crystal. Upon compression, the appearance of prominent fluorescence peaks suggests a phase transition. The Raman peaks, reflecting the C–H and C≡N bonds, exhibit splitting at a pressure of 3.2 GPa, further confirming the pressure-induced phase transition. The splitting is consistent with earlier calculations on the stretching vibration of the C≡N bond for various oligomers and indicates a phase transition from monomers to dimers in 5CB liquid crystal. The opposite shifts in Raman modes under pressure, specifically the blue-shift of C–H bonds and the red-shift of C≡N bonds, indicate that pressure enhances intermolecular interactions and leads to conjugation between the electrons on the C≡N bonds and the C–H bonds, resulting in dimer formation. Our findings not only reveal a novel strategy for producing oligomers in liquid crystals through the application of high pressure but also highlight that Raman spectroscopy is a valid, non-contact method for investigating the mechanisms of oligomerization.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
APPLIED PHYSICS LETTERS
·
2017
·Vol. 110
·期 12
·
IF 3.411
Zhuang YuKai,Dai LiDong,Wu Lei,Li HePing,Hu HaiYing,Liu KaiXiang,Yang LinFei,Pu Chang
This report presents a pressure-induced permanent metallization for MoS 2 under non-hydrostatic conditions. Impedance and Raman spectra were measured to study the pressure-induced structural and electronic transformations of MoS 2 at up to ∼25 GPa in diamond anvil cells under both non-hydrostatic and hydrostatic conditions. The results show evidence for isostructural hexagonal distortion from 2 Hc to 2 Ha and metallization at ∼17 GPa and ∼20 GPa under non-hydrostatic and hydrostatic conditions, respectively. Interestingly, the metallization is irreversible only under non-hydrostatic compression. We attribute this phenomenon to the incorporation of molecules of pressure medium between layers, which mitigate compressed stress and reduce interlayer interaction.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
Microstructures
·
2024
·Vol. 4
·期 1
·N
·
IF 0
Yanmei Ma,Hongbo Wang,Ruihong Li,Han Liu,Jian Zhang,Xianyu Wang,Qiang Jing,Xu Wang,Wenping Dong,Jinman Chen,Bingze Wu,Yonghao Han,Dan Zhou,Chunxiao Gao
Owing to their unique compositional and structural characteristics, layered van der Waals solids in binary and ternary chalcogenide families provide a fertile testbed for exploring novel exotic structures and states, e.g., topological insulators and superconductors. Herein, a comprehensive study on the structural variations and correlated electrical transport behavior of SnSb2Te4, a ternary member, has been carried out considering elevated pressures. Under 45.6 GPa, three distinct structural phase transitions have been observed, with strong evidence from the variations of high-pressure X-ray diffraction patterns. The onsets of phase II (monoclinic, C2/m) at 6.3 GPa, phase III (monoclinic, C2/c) at 15.5 GPa, and phase IV (body-centered cubic with substitutional disorder, Im-3m) at 17.2 GPa have been observed owing to the emergence of new diffractions. Based on electrical measurements at low temperature and high pressure conditions, two pressure-induced superconducting states have been distinguished in SnSb2Te4. The first state occurs in the range of 12.3-17.1 GPa. The positive pressure dependence on Tc indicates that the aforementioned state is related to the monoclinic C2/m phase. At > 17.1 GPa, the second superconducting state emerges, with the negative pressure dependence on Tc. It relates to the body-centered cubic solid solution phase, which is characteristic of a substitutional disordered crystal structure. The discovery that the pressure-induced superconductivity in SnSb2Te4 is affected by structural phase transitions under pressure may help understand the universal relationship between the ambient condition topological insulating state and derived superconductivity. Ab initio theoretical calculations reveal that an electronic topological transition takes place at approximately 2.0 GPa, which is featured by the obvious changes in the distribution of electronic density of states near the Fermi level.
研究领域:
凝聚态物理
·
材料科学
✓ 已验证
DOI
JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Ruihong Li,Guangtao Liu,Qiang Jing,Xianyu Wang,Hongbo Wang,Jian Zhang,Yanmei Ma
The materials with topological phases have been a flexible platform for the realization of novel types of quantum matter due to their unique topology protected electron states. Herein, we report a comprehensive structural and electrical transport investigations on a topological insulator, SnBi 2 Te 4 , under high pressures by using diamond anvil cell techniques. Through in situ high pressure synchrotron x-ray diffraction studies, two structural phase transformations have been revealed. The powdered samples of SnBi 2 Te 4 transform from the initial layered quasi-two-dimensional structure (phase I) to a monoclinic C2/m structure (phase II) at about 7.14 GPa, and eventually develop into a site-disordered body centered cubic structure (phase III) at pressures above 18.9 GPa. Modifications of the electronic band structure have been discovered by the in situ high-pressure electrical measurements at low temperatures. It is noteworthy that three distinct pressure induced superconducting states have been observed, one in phase II and two in phase III. In each of the pressure induced superconducting states, the critical temperature Tc decreases with pressure. The maximum value of Tc is obtained in the third superconducting state emerging at the highest pressure range, which is 8.9 K at 22.3 GPa. A deep understanding of the relationship between the pressure induced structure-dependent superconducting states and the ambient-pressure topologically insulating state of SnBi 2 Te 4 may shed light on the universal physical nature that creates topologically insulating or superconducting states.
研究领域:
凝聚态物理
·
材料科学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2023
·Vol. 11
·期 20
·6588-6596
·
IF 6.4
Yingying Ma,Ting Wen,Ke Liu,Dequan Jiang,Mei-Huan Zhao,Chuanlong Lin,Yonggang Wang
Lanthanide ion (Ln3+)-codoped inorganic materials have been widely studied owing to their unique upconversion photoluminescence (UC PL) performance, which can be employed for promising applications in imaging, sensing, detection, and treatment. However, the forbidden transition of 4f inner shell and the nonradiative relaxation from the interaction of Ln3+ and a host lattice lead to low emission efficiency, limiting the industrial application. In this study, we report pressure-induced 1.2–2.6 times UC PL enhancement in the range of 10.0–25.0 GPa in Ln3+ (19%Yb3+/1%Er3+, 19%Yb3+/1%Ho3+, and 19.9%Yb3+/0.1%Tm3+)-codoped LiYF4 and LiLuF4. In situ X-ray diffraction pattern and Raman spectra indicated that both LiYF4 and LiLuF4 underwent structure transitions at a pressure around 10.0 GPa. Moreover, improved UC emissions were observed for the released sample in a completely amorphous state. The luminescence spectra of Eu3+-doped LiYF4 and LiLuF4 probes revealed that the phase transitions resulted in the reduction of Ln3+ site symmetry. Our research shows that pressure would be a powerful implement to design high-efficiency UC PL materials. Simultaneously, research on the “structure-luminescence” relationship can provide a deeper insight into the exploitation of potential UC PL materials and optimization of current luminescent materials.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Laser & Photonics Reviews
·
2025
·Vol. 19
·期 8
·2401888
·
IF 10
Jie Zhang,Fei Xu,Xiuyan Gao,Zhaojiang You,Yongsheng Gao,Duanqi Ma,Bin Xia,Dehua Wang,Shufang Zhang,Kai Wang
2D bismuth-based perovskites have attention as a potentially transformative technology in optoelectronics due to their exceptional non-toxic and environmentally friendly properties. However, their practical applications are hindered by the low luminous efficiency caused by self-trapped excitons (STEs) under normal environmental conditions. Here, a new composition of lead-free ultrathin 2D perovskite nanosheet iso-octylamine bismuth bromide [(i-OA) 3 BiBr 6 ] is synthesized, with thicknesses down to 1.1 nm, using a solution-based method and explored their stability. Notably, the behavior of STEs in these ultrathin nanosheets can be modulated through a pressure treatment strategy. After completely releasing the pressure, an optimal lattice distortion is stabilized, resulting in an 80-fold increase in irreversible pressure-induced emission. This finding highlights the critical roles of steric hindrance and hydrogen bonding cooperativity effects in the organic cationic layers, along with OA ligand passivation, in enhancing STE radiation recombination under ambient conditions. This advancement opens new possibilities for creating stable, bright STEs under ambient conditions, thus facilitating its potential applications in the fields of pressure sensing, display, and energy savings.
研究领域:
材料科学
·
光学
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
ACS Nano
·
2021
·
IF 15.881
Yueqi Chang,Cheng Dong,Dongxue Zhou,Ang Li,Wenjun Dong,Xue-Zheng Cao,Ge Wang
TiO2 nanohelices (NHs) have attracted extensive attention owing to their high aspect ratio, excellent flexibility, elasticity, and optical properties, which endow promising performances in a vast range of vital fields, such as optics, electronics, and micro/nanodevices. However, preparing rigid TiO2 nanowires (TiO2 NWs) into spatially anisotropic helical structures remains a challenge. Here, a pressure-induced hydrothermal strategy was designed to assemble individual TiO2 NWs into a DNA-like helical structure, in which a Teflon block was placed in an autoclave liner to regulate system pressure and simulate a cell-rich environment. The synthesized TiO2 NHs of 50 nm in diameter and 5–7 mm in length approximately were intertwined into nanohelix bundles (TiO2 NHBs) with a diameter of 20 μm and then assembled into vertical TiO2 nanohelix arrays (NHAs). Theoretical calculations further confirmed that straight TiO2 NWs prefer to convert into helical conformations with minimal entropy (S) and free energy (F) for continuous growth in a confined space. The excellent elastic properties exhibit great potential for applications in flexible devices or buffer materials.
研究领域:
材料科学
·
纳米技术
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2024
·
IF 3.7
Hongyan Yu,Yongxue Chen,Zhenyu Wen,Rensheng Wang,Sisi Jia,Wenjie Zhu,Yanping Song,Huanhuan Sun,Bingbing Liu
Pressure-induced surface-enhanced Raman spectroscopy (PI-SERS) has garnered significant attention as a subfield of SERS detection due to its capacity to regulate the band gap between molecules and substrates through pressure modulation. Currently, SERS detection primarily focuses on single molecules at atmospheric pressure with limited investigations conducted under high pressure conditions. Herein, we employed rose-shaped MoS2 nanoflowers as the SERS substrate and realized selective PI-SERS enhancement of R6G molecules in the binary (MV+R6G) and ternary (MV+R6G+RhB) systems. The MoS2 demonstrated an exceptionally low SERS detection limit of 5 × 10–6 M in binary and ternary systems with equimolar amounts of molecules. High-pressure experimental results indicate that MoS2 displays selective enhancement for R6G molecules, as evidenced by the comparison of the PI-SERS peak intensity ratio between MoS2 and the probe molecules. The proposed enhancement mechanism in binary and ternary SERS systems under high pressure involves pressure-induced changes in both the band structures of the MoS2 substrate and molecules, thereby influencing their charge transfer dynamics. Consequently, this approach holds great promise for practical applications in complex SERS systems operating under extreme conditions.
研究领域:
材料科学
·
光谱学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2021
·
IF 4.527
Yuzhu Su,Junpu Wang,Xin Li,Qiqi Tang,Jing Yang,Li Lei,Yi Tian,Zhiwei Wang,Duanwei He
The in situ axial X-ray diffraction patterns of four ceramic powder samples (MgO, Al 2 O 3 , AlN , and cBN) that were compressed in a diamond anvil cell under uniaxial non-hydrostatic conditions were recorded. The microscopic deviatoric stress as a function of the pressure was determined from the X-ray diffraction peak broadening analysis: the curves increased approximately linearly with the pressure at the initial compression stage and then levelled off under further compression. Pressure-induced transparency was observed in all of the samples under compression, and the pressure at the turning point on the curves of the microscopic deviatoric stress versus pressure corresponded to the pressure at which the samples became transparent. Analysis of the microstructural features of the pressure-induced transparent samples indicated that the compression caused the grains to fracture, and the broken grains bonded with each other. We demonstrated that the ceramics’ pressure-induced transparency was a process during which the grains were squeezed and broken, the pores were close between the grains, and the broken grains were re-bonded under compression.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry A
·
2023
·Vol. 11
·期 36
·19427-19434
·
IF 11.9
Jie Zhang,Mingxing Li,Dehua Wang,Binhua Chu,Shufang Zhang,Qinfeng Xu,Kai Wang
Understanding the fundamental properties of two-dimensional (2D) bismuth-based perovskites is essential for their applications in optoelectronic devices. Here, we report the room-temperature synthesis of 2D Cs3Bi2I6Cl3 nanocrystals (NCs) by an anti-solvent assisted crystallization method, which display a broad emission bandwidth with a large Stokes shift primarily originating from exciton self-trapping caused by strong electron–phonon coupling and the critical contribution of Bi–Cl bonds to the band edge is demonstrated. Furthermore, analysis of combined in situ high pressure PL, absorption, Raman and PL decay data indicates that the observed pressure-induced emission (PIE) enhancement can be attributed to the efficient surface reconstruction accompanied by the removal of surface-related trap states, as the interaction between oleic acid (OA) and Cs3Bi2I6Cl3 is strengthened at high pressure. Pressure-induced structural evolutions are well consistent with changes in their optical properties and of particular importance is the retention of 1.5 times PL intensity after releasing pressure. This highlights the importance of steric hindrance and spring effect of the OA ligand in the defect perovskite family, which retain the octahedral distortion in Cs3Bi2I6Cl3 NCs. Our study not only provides deep insights into the structure–property relationship of 2D Cs3Bi2I6Cl3 NCs, but also offers a basis for improving the performance of 2D lead-free perovskite NCs.
研究领域:
材料科学
·
光学
·
凝聚态物理
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Fanyun Chen,Chen Tian,Xuelin Pan,Qingshan Gao,Qingwei Wang,Liyuan Chai,Zhang Lin
Metallurgical sulfur-containing wastes (MSCWs) is an important secondary resource for recovering element sulfur in chemical and metallurgical industries. However, it is challenging to simultaneously achieve high recovery rate and sulfur purity, due to the multiple impurities combining with sulfur in these wastes. In this paper, we developed a novel method of pressure induced melting-crystallization to efficiently recover sulfur from MSCWs. The effects of condition parameters on the sulfur recovery rate and purity were optimized through response surface methodology. The single objective optimization results showed that the interaction between melting temperature and slurry concentration had a great influence on sulfur purity. The slurry concentration and pressure had great influence on sulfur recovery rate. The results of multi-objective optimization showed that under the conditions of pressure 1.2 MPa, slurry concentration 14.9% and melting temperature 140.9℃, the highest sulfur purity and recovery rate could reach 93.0% and 89.1% respectively. Mechanism investigation revealed that the high efficiency of sulfur recovery was ascribed to recrystallization of molten sulfur under the combined action of pressure and water, forming dense sulfur blocks and separating hydrophilic impurities. This work provides a new way to recover sulfur resources from MSCWs with sulfur content higher than 50%.
研究领域:
冶金工程
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY OF MATERIALS
·
2025
·
IF 7
Wenbo Qiu,Weilong He,Yu Liu,Boyang Fu,Weiyi Wang,Jiangang He,Luhong Wang,Haozhe Liu,Weizhao Cai
Controlling the molecular chirality under external pressure is particularly challenging in low-dimensional hybrid halides, as the constrained structure and strong hydrogen bonding hinder significant conformational changes in bulky organic molecules. Here, by incorporating flexible disulfide-based molecules into the one-dimensional (1D) PbI5 framework, the chiral hybrid halide [NH3(CH2)2S–S(CH2)2NH3]PbI5·H3O undergoes a transformation from conglomerate to racemate at a hydrostatic pressure of approximately 0.10 GPa. This reversible acentric-to-centric transformation is accompanied by the second-harmonic generation (SHG) “on–off” switching and significant conformational changes in the cystamine cations within the structure. In the high-pressure racemic phase, two enantiomers with left- and right-handed conformers (M- and P-helicity) coexist within the lattice structure and their deformations under compression resemble those of a compressed mechanical spring, ultimately leading to considerable distortions of the 1D zigzag PbI5 chains through strong organic–inorganic H···I interactions. Furthermore, both experimental and theoretical results reveal that the unique phase transformation induces minor alterations in the electronic structures and optical bandgaps. Our findings provide insights into the manipulation of molecular chirality and SHG properties in hybrid halides by introducing flexible organic molecules into inorganic frameworks.
研究领域:
材料科学
·
晶体学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）