MOLECULES
·
2018
·Vol. 23
·期 9
·2296
·
IF 3.098
Yao Huang,Run Yang,Shijie Xiong,Jian Chen,Xinglong Wu
Silicon carbide (SiC) has a large number of polytypes of which 3C-, 4H-, 6H-SiC are most common. Since different polytypes have different energy gaps and electrical properties, it is important to identify and characterize various SiC polytypes. Here, Raman scattering is performed on 6H-SiC micro/nanocrystal (MNC) films to investigate all four folded transverse optic (TO) and longitudinal optic (LO) modes. With increasing film thickness, the four folded TO modes exhibit the same frequency downshift, whereas the four folded LO modes show a gradually-reduced downshift. For the same film thickness, all the folded modes show larger frequency downshifts with decreasing MNC size. Based on plasmons on MNCs, these folded modes can be attributed to strong coupling of the folded phonons with plasmons which show different strengths for the different folded modes while changing the film thickness and MNC size. This work provides a useful technique to identify SiC polytypes from Raman scattering.Keywords:SiC micro/nanocrystals;plasmon–phonon coupling;folded phonons
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED FUNCTIONAL MATERIALS
·
2022
·Vol. 32
·期 22
·2111338
·
IF 19.924
Liangling Wang,Wei Zheng,Francesco Vitale,Xiangzhou Zhang,Xiuling Li,Yanchen Ji,Zhen Liu,Omid Ghaebi,Christian T. Plass,Robert Domes,Torsten Frosch,Giancarlo Soavi,Elke Wendler,Yuhai Zhang,Carsten Ronning
Alloyed lead-free double perovskites display intense photoluminescence, are environmentally friendly, and their devices show long-term operation. Thanks to these properties, which make them excellent warm white-emitting materials, they have recently received great attention in lighting applications. An important factor to tune the optical properties of alloyed lead-free double perovskites is the presence of self-trapped excitons. Here, it is demonstrated that in lead-free double perovskites, the strong electron–phonon coupling plays a crucial role in the generation of self-trapped excitons. The strong electron–phonon coupling is confirmed by a large Huang–Rhys factor and by the presence of multiphonon transitions. In particular, sharp emission lines superimposed on the broad photoluminescence emission band of one of these samples (Cs 2 Ag 0.6 Na 0.4 InCl 6 0.5%Bi) are observed; these are due to the strong coupling of longitudinal-optical phonons with excited electronic states caused by the tetragonally distorted AgCl 6 octahedrons. Such a strong coupling of longitudinal-optical phonons to electrons can effectively modulate the photophysical properties of alloyed double perovskites, and its understanding is, thus, of paramount importance for the design of future optoelectronic devices.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
Advanced Energy Materials
·
2025
·Vol. 15
·期 38
·e03481
·
IF 26
Minhui Yuan,Zhen Tong,Qing Cao,Wenjie Li,Min Ruan,Jiahao Jiang,Jingyi Lyu,Yanglong Hou,Ran He,Jing Shuai
N -type Mg 3 (Sb,Bi) 2 system has emerged as a groundbreaking thermoelectric (TE) material, renowned for its optimized electronic transport properties and intrinsically low lattice thermal conductivity (κ l ). However, the origin of anomalously low κ l and its weak temperature scaling (κ l ∼ T −0.5 , deviating from the classical T −1 behavior) remain elusive. Employing a theoretical framework that integrates ab initio anharmonic lattice dynamics into a unified heat transport theory accounting for particle-like propagation (κ p ) and wave-like coherent (κ c ) transport, phonon renormalization, and fourth-order anharmonic phonon scattering, the thermal transport property of Mg 3 Bi 2 is comprehensively investigated. It is found that the weakly bonded interlayer cation Mg atoms amplify phonon coherence through dynamic disorder, driving wave-like transport contributes ≈40% to κ l at 600 K, while four-phonon scattering significantly suppresses particle-like propagation (>40% reduction). The theoretical predictions of both the magnitude and temperature-dependent behavior of κ l in Mg 3 Bi 2 exhibit synergistic agreement with in-house and reported experimental values. This work pioneers key insights into the Mg cation sublattice tuning the particle-wave duality in phonon transport, its strong anharmonic potential disrupts phonon phase coherence while enhancing four-phonon scattering, collectively driving the low κ l in Mg 3 Bi 2 . This discovery provides two actionable design strategies—cation site engineering and coherent phonon tuning—for developing high- zT Mg 3 Bi 2 -based thermoelectrics.
研究领域:
材料科学
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热电学
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凝聚态物理
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声子输运
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计算材料物理
✓ 已验证
DOI
高影响因子
Nature Communications
·
2025
·Vol. 16
·期 1
·1-10
·
IF 15.7
Li Lijia,Chen Jiajun,Hu Laigui,Qiu Zhijun,Zou Zhuo,Liu Ran,Zheng Lirong,Cong Chunxiao
Collective vibration is pivotal for materials’ thermal, electrical, phase transition and topological properties. Lately, the rising of moiré superlattices, characterized by overarching periodicity of moiré pattern, generates highly tunable interfacial structures that manipulate collective excitations in material at the atomic scale. Here, we experimentally demonstrate moiré collective vibrations, the mechanical counterparts of moiré excitons, at heterointerfaces of twisted tungsten diselenide/tungsten disulfide heterobilayers. Using helicity-resolved inelastic Raman scattering, we find chiral interfacial phonons carrying angular momentum analogous to that of chiral bulk phonons in quartz, enabling unprecedented spectral resolution of rich vibrational modes at heterointerface in a few atomic layers. Upon mutual torsion of heterobilayers, we observe terahertz interlayer vibrations proportional to moiré periodicity as a periodic function of rotation angles, demonstrating moiré-tuned interlayer modes which couple to Coulomb-bound electron-hole pairs in interlayer moiré excitons. In low-angle strong coupling regime, interlayer dynamics exhibit a distinct long-lived breathing mode with zero angular momentum and pronounced high energy, highlighting phonon-hybridization character wherein intralayer breathing vibrations are folded into moiré mini-Brillouin zone by spatial periodicity and hybridize with interlayer vibrations. Our findings establish moiré collective vibrations as candidates for exploitation in energy-efficient thermal management, strongly correlated electrical engineering, and new emergent topological phononics.
研究领域:
凝聚态物理
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纳米材料科学
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低维量子系统
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声子工程
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拓扑物态
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ADVANCED MATERIALS
·
2024
·Vol. 36
·期 31
·2400911
·
IF 27.4
Hongxiang Chen,Jiantao Fu,Shuxian Huang,Yiding Qiu,Enhui Zhao,Shiyu Li,Jianeng Huang,Pinqiang Dai,Hengzhong Fan,Bing Xiao
Entropy engineering is widely proven to be effective in achieving ultra-low thermal conductivity for well-performed thermoelectric and heat management applications. However, no strong correlation between entropy and lattice thermal conductivity is found until now, and the fine-tuning of thermal conductivity continuously via entropy-engineering in a wide entropy range is still lacking. Here, a series of high-entropy layered semiconductors, Ni 1− x (Fe 0.25 Co 0.25 Mn 0.25 Zn 0.25 ) x PS 3 , where 0 ≤ x < 1, with low mass/size disorder is designed. High-purity samples with mixing configuration entropy of metal atomic site in a wide range of 0–1.61 R are achieved. Umklapp phonon-phonon scattering is found to be the dominating phonon scattering mechanism, as revealed by the linear T −1 dependence of thermal conductivity. Meanwhile, fine tuning of the lattice thermal conductivity via continuous entropy engineering at metal atomic sites is achieved, in an almost linear dependence in middle-/high- entropy range. Moreover, the slope of the κ - T −1 curve reduces with the increase in entropy, and a linear response of the reduced Grüneisen parameter is revealed. This work provides an entropy engineering strategy by choosing multiple metal elements with low mass/size disorder to achieve the fine tuning of the lattice thermal conductivity and the anharmonic effect.
研究领域:
材料科学
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热电学
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固体物理
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声子工程
✓ 已验证
DOI
高影响因子
Joule
·
2024
·
IF 38.6
Hailong Yang,Baohai Jia,Lin Xie,Dasha Mao,Junchao Xia,Jianmin Yang,Minhui Yuan,Quan Gan,Xusheng Liu,Mingyuan Hu,Jing Shuai,Jiaqing He
Beyond phonon transport, non-propagating transport is also crucial for crystals to achieve ultra-low lattice thermal conductivity (κ L ) approaching the amorphous limitation. In our study, the demonstrated enhancement of phonon localization proves instrumental in achieving ultra-low κ L , offering an understanding of the role of non-propagating transport. We experimentally verified this principle through a meticulously designed vapor-liquid-solid reaction in Mg 3 (Sb,Bi) 2 -based materials. A remarkably low κ L of 0.19 W/mK at room temperature was obtained. This marked a 77% reduction, compared with full-density counterparts, and was attributed to enhanced localization involved in high-frequency phonons. Moreover, we achieved a record zT value close to 1.2 at room temperature, along with the highest average zT value of 1.6 from 300 to 573 K among all n-type materials. These remarkable results align precisely with electron-phonon decoupling through strengthening phonon localization for materials design and application, which underscores the pivotal role in thermal transport.
研究领域:
材料科学
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热电学
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固体物理学
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2023
·
IF 10.9
Yi-Yan Liao,Qiang Sun,Xu-Ping Jiang,Hao Wu,Bang-Zhou Tian,Ze-Gao Wang,Kun Zheng,Lei Yang
The coupling of charge carrier and phonon transport limits the application of Ag 2 Se as a low-toxic near-room-temperature thermoelectric material. Strategies that reduce the thermal conductivity via enhancing the phonon scattering usually lead to reduced carrier mobility due to high grain boundary potential barrier. In this study, we developed a cell-membrane-mimic grain boundary engineering strategy for decoupling the charge carrier and phonon scattering through decorating high-dielectric-constant rutile TiO 2 at Ag 2 Se grain boundaries to enable the charge carrier/phonon selective permeability. The nano-sized TiO 2 with high dielectric permittivity can secure the charge carrier transport by shielding the interfacial Coulomb potential to lower the energy barrier of grain boundaries, rendering an enhanced power factor. Additionally, benefited from the enhanced phonon scattering by TiO 2 nanoparticles, a significantly decreased lattice thermal conductivity of ∼0.20 W m −1 K −1 and a high zT of ∼0.97 at 390 K are obtained in the Ag 2 Se-based nanocomposites. This work demonstrates that such cell-membrane-mimic grain boundary engineering strategy may shed light on developing high-performance thermoelectric materials.
研究领域:
材料科学
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物理学
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2020
·Vol. 7
·期 18
·3371-3378
·
IF 5.958
Yang Zhou,Xiaoming Wang,Cuiping Wang,Tian Zhang,Yonggang Wang,Fan Dou,Huan Jiao
A novel red fluoride phosphor BaNbF7:Mn4+ was synthesized via the conventional co-precipitation method. The structure and luminescence properties of BaNbF7:Mn4+ were investigated and discussed under various conditions. The BaNbF7:Mn4+ phosphor shows strong ZPL emission intensity at about 630 nm under ultraviolet (UV) and blue light excitation. It originated from the highly distorted Mn4+ octahedral coordination environment in the C3v group symmetry surrounding. A WLED fabricated with a blend of YAG:Ce3+ and the BaNbF7:Mn4+ phosphor exhibits a low color temperature (CCT = 3715 K) and a high color rendering index (Ra = 81.2), indicating its potential for application as a red phosphor for WLEDs.
研究领域:
材料科学
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光学
✓ 已验证
DOI
高影响因子
Journal of Materials Chemistry C
·
2023
·Vol. 11
·期 37
·12658-12666
·
IF 6.4
Qiao Qu,Konglan Chen,Yayun Zhou,Jinsheng Li,Haipeng Ji
A K2SiF6:Mn4+ phosphor with narrow line-type red emission plays an important role in white light-emitting diode (WLED) backlights for liquid crystal displays, but this phosphor exhibits weak zero phonon line (ZPL) emission. The ZPL intensity of the Mn4+ 2Eg → 4A2g transition can be enhanced after relaxing the orbital selection rule. We dope Mn4+ into a host lattice with mixed-anions to introduce a distortion of local coordination octahedra around Mn4+ and relax the orbital selection rule. Remarkably, the Na2MoO2F4:Mn4+ phosphor with [MoO2F4] mixed-anion coordination exhibits a dominant luminescence peak at 625 nm (ascribed to the ZPL) and the ZPL to Stokes v6 intensity ratio reaches an unprecedented high value of 243% under 480 nm excitation. Density functional theory calculations indicate that the most energy-efficient pathway for maintaining charge balance during Mn4+-doping involves the substitution of [MoO2F4]2− by [MnF6]2−, which generates a strong crystal field with a high Dq/B value of 4.05 for Mn4+ in Na2MoO2F4. An optimal composition Na2MoO2F4:1.5%Mn4+ (nominal) exhibits a high color purity of 99.3% and a short luminescence lifetime of 0.62 ms, suggesting its potential in fast-response backlight display applications. When incorporated into WLEDs, the red-emitting Na2MoO2F4:Mn4+ phosphor contributes to a broad color gamut (∼108.3% NTSC). Comparative analysis of a series of Mo6+-based oxyfluoride phosphors demonstrates that Mn4+ more readily exhibits intense ZPL and fast luminescence decay occurs when Mo6+ is coordinated in an O/F ordered octahedron.
研究领域:
材料科学
·
光学
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2023
·Vol. 52
·期 17
·5587-5596
·
IF 4
Zhijian Liao,Yan Li,Jiaxing Zuo,Guang Chen,Heng Liang,Shihao Wu,Jiaqing Peng,Xinyu Ye
For high-efficiency lighting and wide color gamut backlight display, high-quality narrow-band red phosphors for WLEDs are still in high demand. Herein, a novel red-emitting fluoride phosphor Cs2NaGaF6:Mn4+ was successfully synthesized by a simple two-step co-precipitation method and exhibits ultra-intense zero-phonon lines (ZPLs) and long wavelength phonon sidebands under 468 nm blue light irradiation. The ZPL emission peak of Cs2NaGaF6:Mn4+ was located at 627 nm, which is much stronger than its υ6 vibration peak, more matchable with the eye-sensitive region of humans, and beneficial for obtaining higher luminous efficiency of WLEDs. Interestingly, the υ6 vibration peak of this red phosphor is at 636.5 nm, which is larger than that of the common fluoride phosphor A2BF6:Mn4+ (usually at about 630 nm, represented by K2SiF6:Mn4+) at about 6.5 nm. Thanks to the longer wavelength of the υ6 vibration peak, the chromaticity coordinates (0.7026, 0.2910) with a larger x-coordinate value were realized, leading to a potentially wider color gamut of WLEDs. In addition, this phosphor has high thermal stability and its emission intensity at 423 K remains 93.7% of the initial intensity at room temperature. The lumen efficiency of WLED1 packaged with a mixture of Cs2NaGaF6:Mn4+ and YAG:Ce3+ on the InGaN blue chip is 115.7 lm W−1 with the color temperature (Tc) = 3390 K and the colour rendering index (Ra) = 92.5 under 20 mA driving current. The chromaticity coordinates of WLED2 packaged with Cs2NaGaF6:Mn4+ and β-SiAlON:Eu2+ on the InGaN blue chip are (0.3149, 0.3262) and the calculated color gamut is up to 118.4% (NTSC). These results indicate that Cs2NaGaF6:Mn4+ red phosphors have promising applications in the high-quality lighting and display fields.
研究领域:
材料科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Today Physics
·
2023
·
IF 11.5
Lin Chen,Mingyu Hu,Jing Feng
Thermal transport management is of great significance for materials such as thermal barrier coatings , photovoltaics , and thermoelectrics . In particular, tremendous efforts have been made to tailor phonon thermal transport to improve performance. This work elucidated origins of low thermal conductivity of ferroelastic (Sm 1-X Yb X )TaO 4 solid solutions from defect-dominated phonon scattering processes. We estimated the influences of point defects (misfits in atomic weight and ionic radius , and oxygen vacancies), ferroelastic domains, and the Umklapp process on thermal transports via the corresponding phonon relaxation time ( τ ). The phonon relaxation time caused by point defects ( τ D ), ferroelastic domains ( τ F ), and the Umklapp process ( τ U ) exhibited a trend of τ D − 1 > τ U − 1 > τ F − 1 , indicating that point defects dominated the thermal transports. The effects of ferroelastic domains on thermal conductivity were estimated according to domain widths and space mismatches between neighboring domains. The approximately parallel relationship between the neighboring domains was beneficial for reducing ferroelastic t - m transition energy. Furthermore, a model was developed to derive the high-temperature thermal conductivity, and the contributions of radiative thermal conductivity were separated from the total thermal conductivity. The analysis of thermal transports can be used in other materials to estimate the contributions of different thermal transport mechanisms to the total thermal conductivity at both low and high temperatures, and to effectively tailor thermal transports according to specific applications.
研究领域:
材料科学
·
物理学
✓ 已验证
产品关联
DOI
高影响因子
Nanoscale
·
2024
·Vol. 16
·期 45
·21031-21038
·
IF 5.8
Hanwen Hu,Yiyan Liao,Shanshan Tan,Chen Li,Jun Tang,Kun Zheng,Lei Yang
Ag2Se has emerged as a promising n-type thermoelectric material; however, its application is limited mainly due to the strongly coupled charge carrier and phonon transport. Enhancing phonon scattering by constructing interfacial complexes often results in low carrier mobility due to its strong carrier scattering resulting from the high energy barrier at the multiphase interface. Inspired by the cell membrane with selective permeability, we construct bio-mimic grain boundaries with TiO2 and MoS2 co-decoration in Ag2Se to decouple electron scattering from strong phonon scattering. The nanostructured TiO2 with a high dielectric constant screens the interfacial Coulomb potential, ensuring efficient carrier transport and reducing the grain boundary barriers, while the few-layer MoS2 provides significant phonon scattering to further reduce the thermal conductivity. This method effectively enhances the zT value of Ag2Se by as much as 60% and also can significantly enhance the theoretical output performance of the thermoelectric device, which highlights the effectiveness of the bio-mimic grain boundary engineering strategy.
研究领域:
材料科学
·
物理学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）