Article
Crystallography
Randy Belanger, James Patrick Clancy, Sheetal Jain, Zahra Yamani, Yu-Chih Tseng, Young-June Kim
Summary: We present the results of inelastic neutron scattering (INS) measurements on the phonon dispersion relation in higher manganese silicides (HMSs). A large single crystal ingot of HMS is synthesized using a slow cooling technique, with Mn15Si26 identified as the primary phase. The sample consists of highly oriented crystallites as confirmed by neutron pole-figure study and thermal conductivity data. Our INS results generally agree with previous experimental and theoretical studies on phonons in HMS; however, we also observe some discrepancies, such as a 5 meV gap at the zone center and a softer dispersion relation for the low-lying twisting mode. We discuss the possible origins of these observations and their implications for the thermal properties of HMS.
Article
Physics, Multidisciplinary
Marios Zacharias, Helene Seiler, Fabio Caruso, Daniela Zahn, Feliciano Giustino, Pantelis C. Kelires, Ralph Ernstorfer
Summary: Inelastic scattering experiments are crucial for mapping fundamental excitations of solids, with a particular focus on the role of multiphonon processes for phonon excitations. A new first-principles methodology has been developed to calculate the all-phonon quantum mechanical structure factor of solids, demonstrating the significance of multiphonon processes in the scattering patterns of black phosphorus. This approach represents a significant step towards interpreting static and time-resolved electron, x-ray, and neutron inelastic scattering data.
PHYSICAL REVIEW LETTERS
(2021)
Article
Materials Science, Multidisciplinary
Bin Wei, Junyan Liu, Qingan Cai, Ahmet Alatas, Ayman H. Said, Meihua Hu, Chen Li, Jiawang Hong
Summary: An exceptional case of thermal conductivity anisotropy in layered pentagonal PdSe2 is reported. The thermal conductivity along the b-axis is surprisingly much greater than along the a-axis. The high anisotropy is attributed to the low-energy phonons along the a-axis and the different buckling structures between the a-axis and the b-axis.
MATERIALS TODAY PHYSICS
(2022)
Article
Materials Science, Multidisciplinary
H. Godfrin, K. Beauvois, A. Sultan, E. Krotscheck, J. Dawidowski, B. Fak, J. Ollivier
Summary: The dispersion relation epsilon(k) of elementary excitations in superfluid He-4 was measured and compared with theoretical predictions, showing agreement. Unique phenomena were observed at low wave vectors. The calculated thermodynamic properties supported experimental results, demonstrating consistency between the measured dispersion curve and heat capacity measurements.
Article
Chemistry, Physical
Ekashmi Rathore, Rinkle Juneja, Debattam Sarkar, Subhajit Roychowdhury, Maiko Kofu, Kenji Nakajima, Abhishek K. Singh, Kanishka Biswas
Summary: This study achieves high thermoelectric performance in Ge-doped n-type PbS material by tuning the electronic structure and reducing thermal conductivity. The enhancement of covalency in chemical bonding and the introduction of nanometer-sized precipitates scatter heat-carrying phonons and lower the lattice thermal conductivity. Experimental results reveal low-frequency phonon modes and ultra-short phonon lifetime that contribute to the low thermal conductivity, while electron localization function analysis confirms the chemical bonding hierarchy and increased covalent bonding.
MATERIALS TODAY ENERGY
(2022)
Article
Chemistry, Inorganic & Nuclear
Yong Xu, Xin Chen, Yili Cao, Kun Lin, Chin-Wei Wang, Qiang Li, Jinxia Deng, Jun Miao, Xianran Xing
Summary: Thermal expansion is a significant issue in materials science and engineering. This study investigates the anomalous thermal expansion of CrB2 and discovers distinctly anisotropic behavior, with positive expansion within the basal plane and negative expansion along the c direction. The research also reveals zero thermal expansion in the unit cell volume within a certain temperature range, and attributes the observed antiferromagnetic-paramagnetic transition at around 90 K to the thermal expansion anomaly. DFT calculations support the notion that the antiferromagnetic ordering is a result of the double exchange interaction of Cr-B-Cr, as there is no chemical binding of the Cr-Cr pair.
CHINESE JOURNAL OF STRUCTURAL CHEMISTRY
(2023)
Article
Chemistry, Applied
Tommy Hofmann, Danny Kojda, Haider Haseeb, Dirk Wallacher, Oleg Sobolev, Klaus Habicht
Summary: This article presents inelastic thermal neutron scattering experiments probing the phonon dispersion in mesoporous silicon with 8 nm pores. The study reveals that phonon group velocities in highly-crystalline silicon are not modified by nanostructuring down to sub-10 nanometer length scales in mesoporous silicon, and there is apparently no effect of structuring on the elastic moduli. No evidence of phonon-softening is found in topologically complex, geometrically disordered mesoporous silicon in contrast to silicon nanotubes and nanoribbons.
MICROPOROUS AND MESOPOROUS MATERIALS
(2021)
Article
Multidisciplinary Sciences
Qiyang Sun, Bin Wei, Yaokun Su, Hillary Smith, Jiao Y. Y. Lin, Douglas L. Abernathy, Chen Li
Summary: The study investigates the impact of spin-phonon coupling on the phonon system through experiments and calculations. Anomalous scattering spectral intensity is identified in antiferromagnetic nickel (II) oxide, revealing strong spin-lattice correlations. Magnetic scattering signature is observed in acoustic phonons, and a modified scattering cross-section model is proposed.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Review
Materials Science, Multidisciplinary
Chuan-Dong Zhou, Bo Liang, Wen-Jie Huang, Jacques-Guillaume Noudem, Xiao-Jian Tan, Jun Jiang
Summary: This review summarizes the recent progress in studying phonon dispersion models and proposes using the modified sinusoidal phonon dispersion model for accurately determining lattice thermal conductivity. Furthermore, experimental methods that can reduce lattice thermal conductivity in thermoelectric materials are reviewed, such as methods that generate standing waves or anharmonic lattice vibrations. A high concentration of standing waves and anharmonic lattice vibrations can effectively suppress excessive lattice thermal conductivity. Finally, this review discusses the challenges of applying sinusoidal phonon dispersion to real materials, which are often complicated and time-consuming, especially when dealing with material defects.
Article
Physics, Multidisciplinary
David Hartich, Aljaz Godec
Summary: The thermodynamic uncertainty relation constrains the timescale on which a finite system can exhibit anomalous kinetics, establishing a connection between stochastic thermodynamics and the field of anomalous dynamics for further investigations of thermodynamic consistency of anomalous diffusion models.
PHYSICAL REVIEW LETTERS
(2021)
Article
Chemistry, Physical
Zhao Wang, Cai Cheng, Heng-Xi Zhou, Ke Liu, Xiao-Lin Zhou
Summary: This study investigates the electronic, phonon, elastic, and thermal properties of two-dimensional square-octagon MoS2 (so-MoS2) using first-principles calculations and theoretical analysis. The results show that so-MoS2 has good flexibility, maintains elastic isotropy under twisting and straining, and exhibits promising thermodynamic properties. The study expands the potential for topological material systems.
APPLIED SURFACE SCIENCE
(2021)
Article
Materials Science, Multidisciplinary
Junyan Liu, Timothy A. Strobel, Haidong Zhang, Doug Abernathy, Chen Li, Jiawang Hong
Summary: The study shows that flat phonon bands in BC8-Si play a critical role in reducing lattice thermal conductivity by enlarging the phonon-phonon scattering phase space. This provides insights into the significant reduction of lattice thermal conductivity in this novel silicon allotrope.
MATERIALS TODAY PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Jianyan Yang, Weijun Ren, Xinguo Zhao, Tatsuya Kikuchi, Ping Miao, Kenji Nakajima, Bing Li, Zhidong Zhang
Summary: High-entropy alloys exhibit extensive atomic occupational disorder on high-symmetric lattices, leading to unique magnetic and thermal transport properties. These alloys show complex magnetic behavior, significantly reduced electrical and thermal conductivities compared to traditional alloys, and thermal transport dominated by defect scattering.
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
(2022)
Article
Materials Science, Multidisciplinary
Xiaohan Zhang, Chunyi Zhang, Cui Zhang, Ping Zhang, Wei Kang
Summary: A systematic investigation of finite-temperature phonon dispersion was conducted using autocorrelation function method and first-principles molecular dynamics method for the [001] direction of BaTiO3 as an illustration of entropy-stabilized structures. The study revealed a unique anharmonicity in the cubic phase, primarily derived from interactions between titanium and oxygen atoms. This anharmonicity strongly damps and smears longitudinal optical phonons but has no noticeable effect on phonon energy shifts. In addition, the anharmonicity results in a nearly constant density distribution in a cubic region around the equilibrium position of the relative motion between titanium and oxygen atoms.
Article
Physics, Multidisciplinary
Peng Wu, Naoki Murai, Tongrui Li, Ryoichi Kajimoto, Mitsutaka Nakamura, Maiko Kofu, Kenji Nakajima, Kang Xia, Kunling Peng, Yue Zhang, Weisheng Zhao
Summary: The study finds that optical phonons play a crucial role in thermal transport and exhibit significant softening and broadening with temperature. This finding not only reveals the importance of optical phonons in thermal transport but also provides vital clues for optimizing the thermoelectric performance of SnS.
NEW JOURNAL OF PHYSICS
(2023)
Article
Materials Science, Multidisciplinary
Sajan Kumar, M. K. Gupta, Prabhatasree Goel, R. Mittal, Olivier Delaire, A. Thamizhavel, S. Rols, S. L. Chaplot
Summary: In this study, the atomic dynamics of Cu2Se and Cu2S compounds were investigated using ab initio molecular dynamics (AIMD) simulations and inelastic neutron scattering experiments. The results revealed the transition from solidlike to liquidlike diffusion behavior in both compounds.
PHYSICAL REVIEW MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Sushree Sarita Sahoo, Mayanak K. Gupta, Ranjan Mittal, G. Vaitheeswaran, V Kanchana
Summary: The study investigated the negative thermal expansion behavior and coefficients of Hg2X2 and HgX2 (X=Cl, I) materials, providing important information for device engineering design.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Chemistry, Inorganic & Nuclear
Matilde Saura-Muzquiz, Bryce G. Mullens, Max Avdeev, Prathap K. Jharapla, G. Vaitheeswaran, M. K. Gupta, R. Mittal, Brendan J. Kennedy
Summary: The temperature dependence of the structure and ground state properties of NH4ReO4 were investigated using NPD and DFT. The anomalous thermal contraction in NH4ReO4 was found to be caused by thermally induced rotational disorder of the NH4 groups, which also led to the unusual tetragonal distortion of the material.
JOURNAL OF SOLID STATE CHEMISTRY
(2022)
Article
Materials Science, Multidisciplinary
Sushree Sarita Sahoo, Vineet Kumar Sharma, Mayanak K. Gupta, Ranjan Mittal, V. Kanchana
Summary: This work presents a theoretical investigation of mercury-based halides in both bulk and monolayer form, demonstrating their potential for opto-electronic device applications. The compounds exhibit direct bandgap behavior and have robust transport and optical properties. Experimental verifications are needed to confirm these findings.
MATERIALS TODAY COMMUNICATIONS
(2022)
Article
Chemistry, Physical
Sajan Kumar, Mayanak K. Gupta, Ranjan Mittal, Niina H. Jalarvo, Sanghamitra Mukhopadhyay, Rakesh Shukla, Srungarpu N. Achary, Alexander I. Kolesnikov, Avesh K. Tyagi, Samrath L. Chaplot
Summary: By manipulating the Li stoichiometry and/or host flexibility through ab initio molecular dynamics (AIMD) simulations, the Li+ conductivity in LiAlGeO4 can be significantly improved, especially through amorphization. Excess Li stoichiometry accelerates Li+ diffusion, while the amorphous structure greatly enhances Li+ diffusion.
ACS APPLIED ENERGY MATERIALS
(2022)
Article
Chemistry, Physical
Sajan Kumar, Mayanak K. Gupta, Prabhatasree Goel, Ranjan Mittal, Sanghamitra Mukhopadhyay, Manh Duc Le, Rakesh Shukla, Srungarpu N. Achary, Avesh K. Tyagi, Samrath L. Chaplot
Summary: We investigated the atomic dynamics and Li+ diffusion in crystalline and amorphous Li2Si2O5 using techniques such as quasielastic neutron scattering (QENS), inelastic neutron scattering (INS), and ab initio molecular dynamics simulations (AIMD). Our findings show that in the amorphous phase of Li2Si2O5, there is a narrow temperature range (700 < T < 775 K) where fast Li+ diffusion occurs, as evidenced by significant quasielastic broadening observed in the QENS measurements. The presence of low-energy phonon density of states (PDOS) in the superionic amorphous phase, which disappears in the non-superionic crystalline phase, further supports the role of low-energy modes in Li+ diffusion. AIMD simulations revealed that these low-energy modes involve large amplitude vibrations of Li coupled with SiO4 vibrations in the amorphous phase. At higher temperatures, these vibrational dynamics contribute to accelerated Li+ diffusion. Above 775 K, the SiO4 vibrational dynamics drive the system into the crystalline phase by locking SiO4 and Li+ into deeper minima of the free energy landscape, causing them to disappear in the crystalline phase. Both experiments and simulations provide valuable insights into the atomic-level stochastic and vibrational dynamics in Li2Si2O5 and their implications for Li+ diffusion and vitrification.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Physical
Qingyong Ren, Mayanak K. Gupta, Min Jin, Jingxuan Ding, Jiangtao Wu, Zhiwei Chen, Siqi Lin, Oscar Fabelo, Jose Alberto Rodriguez-Velamazan, Maiko Kofu, Kenji Nakajima, Marcell Wolf, Fengfeng Zhu, Jianli Wang, Zhenxiang Cheng, Guohua Wang, Xin Tong, Yanzhong Pei, Olivier Delaire, Jie Ma
Summary: Superionic materials have ultralow thermal conductivity and fast ionic diffusion, making them excellent for thermoelectric converters and solid-state electrolytes. However, the correlation between these two features is unclear due to limited understanding of their atomic dynamics. In this study, we investigate ionic diffusion and lattice dynamics in Ag8SnSe6 and identify the interplay between vibrational dynamics and the host framework that enables superionicity. We also find that extreme phonon anharmonicity and weak bonding contribute to the ultralow thermal conductivity. These insights provide a fundamental understanding of atomic dynamics in superionic materials for energy conversion and storage.
Article
Physics, Multidisciplinary
S. Mondal, Tarek Ayadi, Sebastien Lebegue, M. K. Gupta, R. Mittal, G. Vaitheeswaran
Summary: A detailed ab initio study was conducted on solid iodanil (C6I4O2) to investigate its structural, lattice dynamics, and pressure-induced metallization. The study revealed the importance of considering van der Waals correction in determining the structural properties and demonstrated good agreement between computed phonon frequencies and experimental results. The study also highlighted the role of optical phonon modes and quasiparticle correction in understanding the insulator-metal transition and band structure of solid iodanil.
Article
Materials Science, Multidisciplinary
Arul Raj Natarajan, L. Ponvijayakanthan, Mayanak K. Gupta, Ranjan Mittal, David J. Singh, V. Kanchana
Summary: This paper investigates the electronic structure, thermal, and electronic transport properties of layered oxychalcogenides LaAgXO (X = Se, Te) using density functional theory. The results show that LaAgXO exhibits low lattice thermal conductivity and high Seebeck coefficient, reaching 400 mu V/K under optimal p-type doping. Additionally, significant ZT values of 1.63 for p-type and 2.8 for n-type LaAgTeO at 900 K are predicted, surpassing other promising thermoelectric materials.
PHYSICAL REVIEW MATERIALS
(2023)
Article
Materials Science, Multidisciplinary
Arul Raj Natarajan, Mayanak K. Gupta, Ranjan Mittal, V. Kanchana
Summary: In this study, the electronic, thermal, and optical properties of NbS2Cl2 were analyzed using density functional theory. The compound was found to have a small direct bandgap, making it a semiconductor. It also exhibited ultra-low thermal conductivity and significant absorption coefficients, indicating potential applications in thermoelectric and optical devices.
MATERIALS TODAY COMMUNICATIONS
(2023)
Letter
Optics
S. Pathak, A. E. Russo, S. K. Seritan, A. D. Baczewski
Summary: We investigate whether investing additional quantum resources in preparing a ground state improves the aggregate runtime for estimating its energy. We analyze Lin and Tong's near-optimal state preparation algorithm and demonstrate its near quadratic reduction in T-gate count for ground-state-energy estimation. We provide resource estimates specifying the conditions where the added cost of state preparation is worthwhile.
Article
Materials Science, Multidisciplinary
Ranjana Rathore, Abhishek Pathak, Mayanak K. Gupta, Ranjan Mittal, Ruta Kulkarni, A. Thamizhavel, Himanshu Singhal, Ayman H. Said, Dipanshu Bansal
Summary: Charge density wave (CDW) induces periodic modulation of charge density, leading to electronic band-gap opening on Fermi level. In this study, we investigate the CDW distortion and hysteresis in EuTe4 using x-ray scattering. We observe multiple commensurate and incommensurate CDW wave vectors and confirm the presence of competing CDW orders. We also discover nondegenerate metastable states during the hysteretic transition.
Article
Chemistry, Physical
Sajan Kumar, Mayanak K. Gupta, Ranjan Mittal, Santhoshkumar Sundaramoorthy, Amitava Choudhury, Naresh C. Osti, Alexander I. Kolesnikov, Matthew B. Stone, Yongqiang Cheng, Samrath L. Chaplot
Summary: This study investigates the atomic-level features of diffusion in Na3ZnGaX4 (X = S, Se) compounds using microscopic techniques. The study reveals that these compounds exhibit significant ionic conductivity and the structural topology and shallow potential energy barrier pathways of Na2 sites play a critical role in diffusion.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Chemistry, Physical
Mayanak K. Gupta, Sajan Kumar, Ranjan Mittal, Sanjay K. Mishra, Stephane Rols, Olivier Delaire, Arumugum Thamizhavel, P. U. Sastry, Samrath L. Chaplot
Summary: This study reveals the anharmonicity in the phonon spectra of MoSe2 and WSe2 using various experimental techniques and simulation methods. It shows that the anharmonicity plays a crucial role in thermal transport and thermal expansion behavior.
JOURNAL OF MATERIALS CHEMISTRY A
(2023)
Article
Materials Science, Multidisciplinary
Mayanak Kumar Gupta, Sajan Kumar, Ranjan Mittal, Samrath L. Chaplot
Summary: The atomic dynamics investigations on Na-based antiperovskites Na3XY reveal that Na diffusion pathways are not correlated with octahedral rotations, and involve Y displacements and Na vacancies. Low-energy phonon modes are important precursors of Na diffusion, providing initial pathways for the process.