Shima Fasahat, Benedikt Schäfer, Kai Xu, Nadesh Fiuza-Maneiro, Sergio Gómez-Graña, M. Isabel Alonso, Lakshminarayana Polavarapu, Alejandro R. Goñi
Metal halide perovskites exhibit a fairly linear increase of the bandgap with increasing temperature, when crystallized in a tetragonal or cubic phase. In general, both thermal expansion and electron-phonon interaction effects contribute equally to this variation of the gap with temperature. Herein, we have disentangled both contributions in the case of colloidal CsPbBr$_3$ nanocrystals (NCs) by means of photoluminescence (PL) measurements as a function of temperature (from 80 K to ambient) and hydrostatic pressure (from atmospheric to ca. 1 GPa). At around room temperature, CsPbBr$_3$ NCs also show a linear increase of the bandgap with temperature with a slope similar to that of the archetypal methylammonium lead iodide (MAPbI$_3$) perovskite. This is somehow unexpected in view of the recent observations in mixed-cation Cs$_x$MA$_{1-x}$PbI$_3$ single crystals with low Cs content, for which Cs incorporation caused a reduction by a factor of two in the temperature slope of the gap. This effect was ascribed to an anomalous electron-phonon interaction induced by the coupling with vibrational modes admixed with the Cs translational dynamics inside the cage voids. Thus, no trace of anomalous coupling is found in CsPbBr$_3$ NCs. In fact, we show that the linear temperature renormalization exhibited by the gap of CsPbBr$_3$ NCs is shared with most metal halide perovskites, due to a common bonding/antibonding and atomic orbital character of the electronic band-edge states. In this way, we provide a deeper understanding of the gap temperature dependence in the general case when the A-site cation dynamics is not involved in the electron-phonon interaction.
当结晶为四方或立方晶相时，金属卤化物包光体的带隙在温度升高时呈相当线性的增长。一般来说，热膨胀效应和电子-声子相互作用效应对这种带隙随温度变化的影响是相同的。在这里，我们通过测量光致发光（PL）与温度（从 80 K 到环境温度）和静水压力（从大气压到约 1 GPa）的函数关系，对胶体 CsPbBr$_3$ 纳米晶体（NCs）的情况进行了分析。在室温左右，CsPbBr$_3$ NCs 的带隙也随温度呈线性增长，其斜率与典型的甲基碘化铵铅 (MAPbI$_3$) 包晶的斜率相似。鉴于最近在铯含量较低的混合阳离子 Cs$_x$MA$_{1-x}$PbI$_3$ 单晶中观察到的情况，这多少有些出乎意料。这种效应可归因于笼状空隙内与 C 晶体动态混合的振动模式耦合引起的异常电子-声子相互作用。因此，在 CsPbBr$_3$ NCs 中没有发现异常耦合的痕迹。事实上，我们的研究表明，CsPbBr$_3$ NCs 间隙所表现出的线性温度重正化与大多数金属卤化物包晶石相同，这是由于电子带边态具有共同的成键/反成键和原子轨道特性。这样，当 A 位阳离子动力学不参与电子-声子相互作用时，我们就能更深入地理解一般情况下的间隙温度依赖性。
{"title":"Absence of Anomalous Electron-Phonon Coupling in the Temperature Renormalization of the Gap of CsPbBr$_3$ Nanocrystals","authors":"Shima Fasahat, Benedikt Schäfer, Kai Xu, Nadesh Fiuza-Maneiro, Sergio Gómez-Graña, M. Isabel Alonso, Lakshminarayana Polavarapu, Alejandro R. Goñi","doi":"arxiv-2409.06374","DOIUrl":"https://doi.org/arxiv-2409.06374","url":null,"abstract":"Metal halide perovskites exhibit a fairly linear increase of the bandgap with\u0000increasing temperature, when crystallized in a tetragonal or cubic phase. In\u0000general, both thermal expansion and electron-phonon interaction effects\u0000contribute equally to this variation of the gap with temperature. Herein, we\u0000have disentangled both contributions in the case of colloidal CsPbBr$_3$\u0000nanocrystals (NCs) by means of photoluminescence (PL) measurements as a\u0000function of temperature (from 80 K to ambient) and hydrostatic pressure (from\u0000atmospheric to ca. 1 GPa). At around room temperature, CsPbBr$_3$ NCs also show\u0000a linear increase of the bandgap with temperature with a slope similar to that\u0000of the archetypal methylammonium lead iodide (MAPbI$_3$) perovskite. This is\u0000somehow unexpected in view of the recent observations in mixed-cation\u0000Cs$_x$MA$_{1-x}$PbI$_3$ single crystals with low Cs content, for which Cs\u0000incorporation caused a reduction by a factor of two in the temperature slope of\u0000the gap. This effect was ascribed to an anomalous electron-phonon interaction\u0000induced by the coupling with vibrational modes admixed with the Cs\u0000translational dynamics inside the cage voids. Thus, no trace of anomalous\u0000coupling is found in CsPbBr$_3$ NCs. In fact, we show that the linear\u0000temperature renormalization exhibited by the gap of CsPbBr$_3$ NCs is shared\u0000with most metal halide perovskites, due to a common bonding/antibonding and\u0000atomic orbital character of the electronic band-edge states. In this way, we\u0000provide a deeper understanding of the gap temperature dependence in the general\u0000case when the A-site cation dynamics is not involved in the electron-phonon\u0000interaction.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Devesh R. Kripalani, Qiye Guan, Hejin Yan, Yongqing Cai, Kun Zhou
Ferroelasticity describes a phenomenon in which a material exhibits two or more equally stable orientation variants and can be switched from one form to another under an applied stress. Recent works have demonstrated that two-dimensional layered organic$-$inorganic hybrid Ruddlesden$-$Popper perovskites can serve as ideal platforms for realizing ferroelasticity, however, the ferroelastic (FE) behavior of structures with a single octahedra layer such as (BA)$_2$PbI$_4$ (BA = CH$_3$(CH$_2$)$_3$NH$_3$$^+$) has remained elusive. Herein, by using a combined first-principles and metadynamics approach, the FE behavior of (BA)$_2$PbI$_4$ under mechanical and thermal stresses is uncovered. FE switching is mediated by cross-plane intermolecular coupling, which could occur through multiple rotational modes, rendering the formation of FE domains and several metastable paraelastic (PE) phases. Such metastable phases are akin to wrinkled structures in other layered materials and can act as a "funnel" of hole carriers. Thermal excitation tends to flatten the kinetic barriers of the transition pathways between orientation variants, suggesting an enhanced concentration of metastable PE states at high temperatures, while halogen mixing with Br raises these barriers and conversely lowers the concentration of PE states. These findings reveal the rich structural diversity of (BA)$_2$PbI$_4$ domains, which can play a vital role in enhancing the optoelectronic properties of the perovskite and raise exciting prospects for mechanical switching, shape memory, and information processing.
铁弹性描述了一种现象，在这种现象中，一种材料表现出两种或两种以上同样稳定的取向变体，并能在外加应力作用下从一种形式切换到另一种形式。最近的研究表明，二维层状有机$$-无机杂化 Ruddlesden$-$Popperovskites 可以作为实现铁弹性的理想平台，然而，具有单个八面体层（如 (BA)$_2$PbI$_4$（BA = CH$_3$(CH$_2$)$_3$NH$_3$^+$ ）的结构的铁弹性（FE）行为仍然是一个未知数。在这里，通过使用第一原理和元动力学相结合的方法，揭示了 (BA)$_2$PbI$_4$ 在机械和热应力下的 FE 行为。FE 开关由跨面分子间耦合介导，可能通过多种旋转模式发生，从而形成 FE 域和几种可蜕变的副弹性（PE）相。这种可变相类似于其他层状材料中的皱褶结构，可以充当空穴载流子的 "漏斗"。热激发倾向于平缓取向变体之间过渡途径的动力学势垒，这表明在高温下可蜕变的 PE 状态的浓度会增加，而卤素与 Br 的混合则会提高这些势垒，反之则会降低 PE 状态的浓度。这些发现揭示了 (BA)$_2$PbI$_4$ 结构域的丰富多样性，它们在增强包晶的光电特性方面发挥着重要作用，并为机械开关、形状记忆和信息处理带来了令人兴奋的前景。
{"title":"Ferroelasticity in Two-Dimensional Hybrid Ruddlesden$-$Popper Perovskites Mediated by Cross-Plane Intermolecular Coupling and Metastable Funnel-Like Phases","authors":"Devesh R. Kripalani, Qiye Guan, Hejin Yan, Yongqing Cai, Kun Zhou","doi":"arxiv-2409.06333","DOIUrl":"https://doi.org/arxiv-2409.06333","url":null,"abstract":"Ferroelasticity describes a phenomenon in which a material exhibits two or\u0000more equally stable orientation variants and can be switched from one form to\u0000another under an applied stress. Recent works have demonstrated that\u0000two-dimensional layered organic$-$inorganic hybrid Ruddlesden$-$Popper\u0000perovskites can serve as ideal platforms for realizing ferroelasticity,\u0000however, the ferroelastic (FE) behavior of structures with a single octahedra\u0000layer such as (BA)$_2$PbI$_4$ (BA = CH$_3$(CH$_2$)$_3$NH$_3$$^+$) has remained\u0000elusive. Herein, by using a combined first-principles and metadynamics\u0000approach, the FE behavior of (BA)$_2$PbI$_4$ under mechanical and thermal\u0000stresses is uncovered. FE switching is mediated by cross-plane intermolecular\u0000coupling, which could occur through multiple rotational modes, rendering the\u0000formation of FE domains and several metastable paraelastic (PE) phases. Such\u0000metastable phases are akin to wrinkled structures in other layered materials\u0000and can act as a \"funnel\" of hole carriers. Thermal excitation tends to flatten\u0000the kinetic barriers of the transition pathways between orientation variants,\u0000suggesting an enhanced concentration of metastable PE states at high\u0000temperatures, while halogen mixing with Br raises these barriers and conversely\u0000lowers the concentration of PE states. These findings reveal the rich\u0000structural diversity of (BA)$_2$PbI$_4$ domains, which can play a vital role in\u0000enhancing the optoelectronic properties of the perovskite and raise exciting\u0000prospects for mechanical switching, shape memory, and information processing.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Neural network potential based molecular dynamics (MD) simulations on the excellent H conductor LaH2.75O0.125 show that O starts diffusing above a critical temperature of Tc~550 K, according to the variance of atom positions regardless of the time step. The original diffusion process at temperatures below Tc has an activation barrier of 0.25 eV. Use of MD simulations with various O and La mass revealed, at above Tc, the coexistence of the 0.25 eV process and an additional diffusion process with an activation barrier of 0.20 eV. The O and La have strongly anharmonic characters.
基于神经网络势的分子动力学（MD）模拟显示，无论时间步长如何，O 在临界温度 Tc~550 K 以上开始扩散。温度低于 Tc 时的原始扩散过程的激活势垒为 0.25 eV。利用不同 O 和 La 质量的 MD 模拟发现，在温度高于 Tc 时，0.25 eV 过程与活化势垒为 0.20eV 的附加扩散过程共存。O 和 La 具有强烈的非谐波特性。
{"title":"Effect of very slow O diffusion at high temperature on very fast H diffusion in the hydride ion conductor LaH2.75O0.125","authors":"Yoyo Hinuma","doi":"arxiv-2409.05353","DOIUrl":"https://doi.org/arxiv-2409.05353","url":null,"abstract":"Neural network potential based molecular dynamics (MD) simulations on the\u0000excellent H conductor LaH2.75O0.125 show that O starts diffusing above a\u0000critical temperature of Tc~550 K, according to the variance of atom positions\u0000regardless of the time step. The original diffusion process at temperatures\u0000below Tc has an activation barrier of 0.25 eV. Use of MD simulations with\u0000various O and La mass revealed, at above Tc, the coexistence of the 0.25 eV\u0000process and an additional diffusion process with an activation barrier of 0.20\u0000eV. The O and La have strongly anharmonic characters.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kento Katagiri, Tatiana Pikuz, Lichao Fang, Bruno Albertazzi, Shunsuke Egashira, Yuichi Inubushi, Genki Kamimura, Ryosuke Kodama, Michel Koenig, Bernard Kozioziemski, Gooru Masaoka, Kohei Miyanishi, Hirotaka Nakamura, Masato Ota, Gabriel Rigon, Youichi Sakawa, Takayoshi Sano, Frank Schoofs, Zoe J. Smith, Keiichi Sueda, Tadashi Togashi, Tommaso Vinci, Yifan Wang, Makina Yabashi, Toshinori Yabuuchi, Leora E. Dresselhaus-Marais, Norimasa Ozaki
In their comment (1), Hawreliak et al. claims that our observation of stacking fault formation and transonic dislocation propagation in diamond (2) is not valid as they interpret the observed features as cracks. In this response letter, we describe our rationale for interpreting the observed features as stacking faults. We also address other points raised in their comments, including the clarifications of how the results of Makarov et al. (3) are not in conflict with our study.
{"title":"Comment on \"Comments regarding \"Transonic dislocation propagation in diamond\" by Katagiri, et al. (Science 382, 69-72, 2023)\" by Hawreliak, et al. (arXiv:2401.04213)","authors":"Kento Katagiri, Tatiana Pikuz, Lichao Fang, Bruno Albertazzi, Shunsuke Egashira, Yuichi Inubushi, Genki Kamimura, Ryosuke Kodama, Michel Koenig, Bernard Kozioziemski, Gooru Masaoka, Kohei Miyanishi, Hirotaka Nakamura, Masato Ota, Gabriel Rigon, Youichi Sakawa, Takayoshi Sano, Frank Schoofs, Zoe J. Smith, Keiichi Sueda, Tadashi Togashi, Tommaso Vinci, Yifan Wang, Makina Yabashi, Toshinori Yabuuchi, Leora E. Dresselhaus-Marais, Norimasa Ozaki","doi":"arxiv-2409.05984","DOIUrl":"https://doi.org/arxiv-2409.05984","url":null,"abstract":"In their comment (1), Hawreliak et al. claims that our observation of\u0000stacking fault formation and transonic dislocation propagation in diamond (2)\u0000is not valid as they interpret the observed features as cracks. In this\u0000response letter, we describe our rationale for interpreting the observed\u0000features as stacking faults. We also address other points raised in their\u0000comments, including the clarifications of how the results of Makarov et al. (3)\u0000are not in conflict with our study.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Silvère PanissetUniv. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, FranceUniv. Grenoble Alpes, CNRS, Grenoble INP, SIMAP, Grenoble, France, Alexander SchmidTU Wien, Institute of Chemical Technologies and Analytics, Vienna, Austria, Alexander StanglUniv. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France, Juergen FleigTU Wien, Institute of Chemical Technologies and Analytics, Vienna, Austria, David JauffresUniv. Grenoble Alpes, CNRS, Grenoble INP, SIMAP, Grenoble, France, Mónica BurrielUniv. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France
The increasing demand for energy storage solutions has spurred intensive research into next-generation battery technologies. Oxygen-ion batteries (OIBs), which leverage mixed ionic-electronic conducting (MIEC) oxides, have emerged as promising candidates due to their solid, non-flammable nature and potential for high power densities. This study investigates the use of over-stoichiometric La2NiO4+delta (L2NO4) as a cathode material for OIBs, exploring its capacity for electrochemical energy storage. Half-cell measurements reveal that L2NO4 with a closed-pore microstructure can store oxygen, achieving a volumetric charge of 63 mA.h.cm-3 at 400 {deg}C with a current density of 3.6 uA.cm-2 and potentials up to 0.75 V vs. 1 bar O2. Additionally, a functional full cell combining over-stoichiometric L2NO4 and under-stoichiometric La0.5Sr0.5Cr0.2Mn0.8O3-delta (LSCrMn) has been successfully developed, demonstrating excellent cyclability and coulomb efficiency. The full cell reaches a maximum volumetric charge of 90 mA.h.cm-3 at 400 {deg}C, 17.8 uA.cm-2, and a cut-off voltage of 1.8 V. This proof of concept underscores the viability of combining over- and under-stoichiometric MIEC materials in OIBs and provides critical insights into optimizing electrode materials and tuning oxygen content for improved performance. This research lays the groundwork for future advancements in OIB technology, aiming to develop materials with lower resistance and higher efficiency.
{"title":"Exploring the potential of combining over- and under-stoichiometric MIEC materials for Oxygen-Ion Batteries","authors":"Silvère PanissetUniv. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, FranceUniv. Grenoble Alpes, CNRS, Grenoble INP, SIMAP, Grenoble, France, Alexander SchmidTU Wien, Institute of Chemical Technologies and Analytics, Vienna, Austria, Alexander StanglUniv. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France, Juergen FleigTU Wien, Institute of Chemical Technologies and Analytics, Vienna, Austria, David JauffresUniv. Grenoble Alpes, CNRS, Grenoble INP, SIMAP, Grenoble, France, Mónica BurrielUniv. Grenoble Alpes, CNRS, Grenoble INP, LMGP, Grenoble, France","doi":"arxiv-2409.05582","DOIUrl":"https://doi.org/arxiv-2409.05582","url":null,"abstract":"The increasing demand for energy storage solutions has spurred intensive\u0000research into next-generation battery technologies. Oxygen-ion batteries\u0000(OIBs), which leverage mixed ionic-electronic conducting (MIEC) oxides, have\u0000emerged as promising candidates due to their solid, non-flammable nature and\u0000potential for high power densities. This study investigates the use of\u0000over-stoichiometric La2NiO4+delta (L2NO4) as a cathode material for OIBs,\u0000exploring its capacity for electrochemical energy storage. Half-cell\u0000measurements reveal that L2NO4 with a closed-pore microstructure can store\u0000oxygen, achieving a volumetric charge of 63 mA.h.cm-3 at 400 {deg}C with a\u0000current density of 3.6 uA.cm-2 and potentials up to 0.75 V vs. 1 bar O2.\u0000Additionally, a functional full cell combining over-stoichiometric L2NO4 and\u0000under-stoichiometric La0.5Sr0.5Cr0.2Mn0.8O3-delta (LSCrMn) has been\u0000successfully developed, demonstrating excellent cyclability and coulomb\u0000efficiency. The full cell reaches a maximum volumetric charge of 90 mA.h.cm-3\u0000at 400 {deg}C, 17.8 uA.cm-2, and a cut-off voltage of 1.8 V. This proof of\u0000concept underscores the viability of combining over- and under-stoichiometric\u0000MIEC materials in OIBs and provides critical insights into optimizing electrode\u0000materials and tuning oxygen content for improved performance. This research\u0000lays the groundwork for future advancements in OIB technology, aiming to\u0000develop materials with lower resistance and higher efficiency.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kwan Ho Au-Yeung, Suchetana Sarkar, Sattwick Haldar, Pranjit Das, Tim Kühne, Dmitry A. Ryndyk, Preeti Bhauriyal, Stefan Kaskel, Thomas Heine, Gianaurelio Cuniberti, Andreas Schneemann, Francesca Moresco
Non-planar aromatic molecules are interesting systems for organic electronics and optoelectronics applications due to their high stability and electronic properties. By using scanning tunneling microscopy and spectroscopy, we investigated thianthrene-based molecules adsorbed on Au(111), which are non-planar in the gas phase and the bulk solid state. Varying the molecular coverage leads to the formation of two different kinds of self-assembled structures: close-packed islands and quasi one-dimensional chains. We found that the molecules are non-planar within the close-packed islands, while the configuration is planar in the molecular chain and for single adsorbed molecules. Using vertical tip manipulation to isolate a molecule from the island, we demonstrate the conversion of a non-planar molecule to its planar configuration. We discuss the two different geometries and their electronic properties with the support of density functional theory calculations.
{"title":"Tuning the Planarity of an Aromatic Thianthrene-Based Molecule on Au(111)","authors":"Kwan Ho Au-Yeung, Suchetana Sarkar, Sattwick Haldar, Pranjit Das, Tim Kühne, Dmitry A. Ryndyk, Preeti Bhauriyal, Stefan Kaskel, Thomas Heine, Gianaurelio Cuniberti, Andreas Schneemann, Francesca Moresco","doi":"arxiv-2409.05489","DOIUrl":"https://doi.org/arxiv-2409.05489","url":null,"abstract":"Non-planar aromatic molecules are interesting systems for organic electronics\u0000and optoelectronics applications due to their high stability and electronic\u0000properties. By using scanning tunneling microscopy and spectroscopy, we\u0000investigated thianthrene-based molecules adsorbed on Au(111), which are\u0000non-planar in the gas phase and the bulk solid state. Varying the molecular\u0000coverage leads to the formation of two different kinds of self-assembled\u0000structures: close-packed islands and quasi one-dimensional chains. We found\u0000that the molecules are non-planar within the close-packed islands, while the\u0000configuration is planar in the molecular chain and for single adsorbed\u0000molecules. Using vertical tip manipulation to isolate a molecule from the\u0000island, we demonstrate the conversion of a non-planar molecule to its planar\u0000configuration. We discuss the two different geometries and their electronic\u0000properties with the support of density functional theory calculations.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ryan Jacobs, Maciej P. Polak, Lane E. Schultz, Hamed Mahdavi, Vasant Honavar, Dane Morgan
We demonstrate the ability of large language models (LLMs) to perform material and molecular property regression tasks, a significant deviation from the conventional LLM use case. We benchmark the Large Language Model Meta AI (LLaMA) 3 on several molecular properties in the QM9 dataset and 24 materials properties. Only composition-based input strings are used as the model input and we fine tune on only the generative loss. We broadly find that LLaMA 3, when fine-tuned using the SMILES representation of molecules, provides useful regression results which can rival standard materials property prediction models like random forest or fully connected neural networks on the QM9 dataset. Not surprisingly, LLaMA 3 errors are 5-10x higher than those of the state-of-the-art models that were trained using far more granular representation of molecules (e.g., atom types and their coordinates) for the same task. Interestingly, LLaMA 3 provides improved predictions compared to GPT-3.5 and GPT-4o. This work highlights the versatility of LLMs, suggesting that LLM-like generative models can potentially transcend their traditional applications to tackle complex physical phenomena, thus paving the way for future research and applications in chemistry, materials science and other scientific domains.
{"title":"Regression with Large Language Models for Materials and Molecular Property Prediction","authors":"Ryan Jacobs, Maciej P. Polak, Lane E. Schultz, Hamed Mahdavi, Vasant Honavar, Dane Morgan","doi":"arxiv-2409.06080","DOIUrl":"https://doi.org/arxiv-2409.06080","url":null,"abstract":"We demonstrate the ability of large language models (LLMs) to perform\u0000material and molecular property regression tasks, a significant deviation from\u0000the conventional LLM use case. We benchmark the Large Language Model Meta AI\u0000(LLaMA) 3 on several molecular properties in the QM9 dataset and 24 materials\u0000properties. Only composition-based input strings are used as the model input\u0000and we fine tune on only the generative loss. We broadly find that LLaMA 3,\u0000when fine-tuned using the SMILES representation of molecules, provides useful\u0000regression results which can rival standard materials property prediction\u0000models like random forest or fully connected neural networks on the QM9\u0000dataset. Not surprisingly, LLaMA 3 errors are 5-10x higher than those of the\u0000state-of-the-art models that were trained using far more granular\u0000representation of molecules (e.g., atom types and their coordinates) for the\u0000same task. Interestingly, LLaMA 3 provides improved predictions compared to\u0000GPT-3.5 and GPT-4o. This work highlights the versatility of LLMs, suggesting\u0000that LLM-like generative models can potentially transcend their traditional\u0000applications to tackle complex physical phenomena, thus paving the way for\u0000future research and applications in chemistry, materials science and other\u0000scientific domains.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The structural properties of amorphous GeO$_2$, a prototypical network glass, were investigated under ambient to high pressure using reverse Monte Carlo simulations based on reported structure factors from in situ high-pressure neutron diffraction experiments with isotopic substitution. The results indicate the retention of the topological structure containing predominantly tetrahedral GeO$_4$ units up to ca.~SI{4}{gigapascal} ($rho/rho_0 = 1.15$), which is explained by the reduction of cavity volumes. With further application of pressure, an increase in the number of GeO$_5$ units is first observed, which is then followed more gradually by an increase in the number of GeO$_6$ units.
{"title":"Structural Analysis of Amorphous GeO$_2$ under High Pressure Using Reverse Monte Carlo Simulations","authors":"Kenta Matsutani, Asumi Yamauchi, Shusuke Kasamatsu, Takeshi Usuki","doi":"arxiv-2409.05604","DOIUrl":"https://doi.org/arxiv-2409.05604","url":null,"abstract":"The structural properties of amorphous GeO$_2$, a prototypical network glass,\u0000were investigated under ambient to high pressure using reverse Monte Carlo\u0000simulations based on reported structure factors from in situ high-pressure\u0000neutron diffraction experiments with isotopic substitution. The results\u0000indicate the retention of the topological structure containing predominantly\u0000tetrahedral GeO$_4$ units up to ca.~SI{4}{gigapascal} ($rho/rho_0 =\u00001.15$), which is explained by the reduction of cavity volumes. With further\u0000application of pressure, an increase in the number of GeO$_5$ units is first\u0000observed, which is then followed more gradually by an increase in the number of\u0000GeO$_6$ units.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142187929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Lopes Seeger, F. Millo, G. Soares, J. -V. Kim, A. Solignac, G. de Loubens, T. Devolder
The traditional method for exciting spin-wave dynamics in magnetic materials involves microwave magnetic fields generated by current injection into inductive antennas. However, there is a growing interest in non-inductive excitation methods. Magneto-acoustic effects present a viable alternative, where strains produced by applying voltages to a piezoelectric substrate can couple to spin-waves in a magnetic film. Recently, it has been proposed that surface acoustic waves (SAWs) can excite the gyrotropic mode of the vortex state in a magnetic disk. Here we report on experiments utilizing a magnetic resonance force microscope to investigate magnetization dynamics in CoFeB sub-micrometer disks in the vortex state, grown on a Z-cut LiNbO$_3$ substrate. The device design enables excitation of the gyrotropic mode either inductively, using an antenna on top of the disks, or acoustically via SAWs launched from an interdigital transducer. Our modelling indicates that the lattice rotation {omega}xz generates a localized magneto-acoustic field that displaces the vortex core from the disk center, initiating the gyration motion. Tuning of the magneto-acoustic torque acting on the vortex structure is achieved by a perpendicular magnetic field. These results demonstrate the clear excitation of the vortex gyrotropic mode by magneto-acoustic excitation.
{"title":"Experimental observation of vortex gyrotropic mode excited by surface acoustic waves","authors":"R. Lopes Seeger, F. Millo, G. Soares, J. -V. Kim, A. Solignac, G. de Loubens, T. Devolder","doi":"arxiv-2409.05998","DOIUrl":"https://doi.org/arxiv-2409.05998","url":null,"abstract":"The traditional method for exciting spin-wave dynamics in magnetic materials\u0000involves microwave magnetic fields generated by current injection into\u0000inductive antennas. However, there is a growing interest in non-inductive\u0000excitation methods. Magneto-acoustic effects present a viable alternative,\u0000where strains produced by applying voltages to a piezoelectric substrate can\u0000couple to spin-waves in a magnetic film. Recently, it has been proposed that\u0000surface acoustic waves (SAWs) can excite the gyrotropic mode of the vortex\u0000state in a magnetic disk. Here we report on experiments utilizing a magnetic\u0000resonance force microscope to investigate magnetization dynamics in CoFeB\u0000sub-micrometer disks in the vortex state, grown on a Z-cut LiNbO$_3$ substrate.\u0000The device design enables excitation of the gyrotropic mode either inductively,\u0000using an antenna on top of the disks, or acoustically via SAWs launched from an\u0000interdigital transducer. Our modelling indicates that the lattice rotation\u0000{omega}xz generates a localized magneto-acoustic field that displaces the\u0000vortex core from the disk center, initiating the gyration motion. Tuning of the\u0000magneto-acoustic torque acting on the vortex structure is achieved by a\u0000perpendicular magnetic field. These results demonstrate the clear excitation of\u0000the vortex gyrotropic mode by magneto-acoustic excitation.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study employs an integral transform approach for Love wave propagation in a rotating composite structure having an interfacial crack. The structure comprises an initially stressed functionally graded piezoelectric viscoelastic half-space bonded to a piezoelectric viscoelastic half-space. The study focuses on two material systems: Epoxy-BNKLBT paired with Epoxy-KNLNTS and Epoxy-BNKLBT paired with Epoxy-PZT7A. The viscoelastic materials are modeled to reflect their complex behavior under rotational and stress conditions. The Galilean transformation is applied to convert the Cartesian coordinates system into a moving reference frame aligned with the Love wave's propagation. Employing Bessel function properties, the system is converted into a set of double integral equations and subsequently reformulated into simultaneous Fredholm integral equations. Numerical solutions to these Fredholm integral equations are used to calculate the electric displacement intensity factor (EDIF) and stress intensity factor (SIF) near the interfacial crack. The key objective of this study is to visualize the impact of different material parameters, like piezoelectric constants, dielectric constants, initial stress, interface electric displacement, interface stress, and rotation, on SIF and EDIF. The investigations of this study will be helpful for advanced technologies like surface acoustic wave (SAW) sensors and piezoelectric actuators, as well as to enhance SAW bio-sensor sensitivity and stability for early cancer detection and biomedical implants.
{"title":"Integral transform technique for determining stress intensity factor in wave propagation through functionally graded piezoelectric-viscoelastic structure","authors":"Diksha, Soniya Chaudhary, Pawan Kumar Sharma","doi":"arxiv-2409.05472","DOIUrl":"https://doi.org/arxiv-2409.05472","url":null,"abstract":"This study employs an integral transform approach for Love wave propagation\u0000in a rotating composite structure having an interfacial crack. The structure\u0000comprises an initially stressed functionally graded piezoelectric viscoelastic\u0000half-space bonded to a piezoelectric viscoelastic half-space. The study focuses\u0000on two material systems: Epoxy-BNKLBT paired with Epoxy-KNLNTS and Epoxy-BNKLBT\u0000paired with Epoxy-PZT7A. The viscoelastic materials are modeled to reflect\u0000their complex behavior under rotational and stress conditions. The Galilean\u0000transformation is applied to convert the Cartesian coordinates system into a\u0000moving reference frame aligned with the Love wave's propagation. Employing\u0000Bessel function properties, the system is converted into a set of double\u0000integral equations and subsequently reformulated into simultaneous Fredholm\u0000integral equations. Numerical solutions to these Fredholm integral equations\u0000are used to calculate the electric displacement intensity factor (EDIF) and\u0000stress intensity factor (SIF) near the interfacial crack. The key objective of\u0000this study is to visualize the impact of different material parameters, like\u0000piezoelectric constants, dielectric constants, initial stress, interface\u0000electric displacement, interface stress, and rotation, on SIF and EDIF. The\u0000investigations of this study will be helpful for advanced technologies like\u0000surface acoustic wave (SAW) sensors and piezoelectric actuators, as well as to\u0000enhance SAW bio-sensor sensitivity and stability for early cancer detection and\u0000biomedical implants.","PeriodicalId":501234,"journal":{"name":"arXiv - PHYS - Materials Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142188198","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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