The ionic conductivity at the grain boundaries (GBs) in oxide ceramics is typically several orders of magnitude lower than that within the grain interior. This detrimental GB effect is the main bottleneck for designing high-performance ceramic electrolytes intended for use in solid-state lithium-ion batteries, fuel cells, and electrolyzer cells. The macroscopic ionic conductivity in oxide ceramics is essentially governed by the underlying polycrystalline microstructures where GBs and grain morphology go hand in hand. This provides the possibility to enhance the ion conductivity by microstructure engineering. To this end, a thorough understanding of microstructure–property correlation is highly desirable. In this work, we investigate numerous polycrystalline microstructure samples with varying grain and grain boundary features. Their macroscopic ionic conductivities are numerically evaluated by the finite element homogenization method, whereby the GB resistance is explicitly regarded. The influence of different microstructural features on the effective ionic conductivity is systematically studied. The microstructure–property relationships are revealed. Additionally, a graph neural network-based machine learning model is constructed and trained. It can accurately predict the effective ionic conductivity for a given polycrystalline microstructure. This work provides crucial quantitative guidelines for optimizing the ionic conducting performance of oxide ceramics by tailoring microstructures.
{"title":"Unraveling impacts of polycrystalline microstructures on ionic conductivity of ceramic electrolytes by computational homogenization and machine learning","authors":"Xiang-Long Peng, Bai-Xiang Xu","doi":"10.1063/5.0223138","DOIUrl":"https://doi.org/10.1063/5.0223138","url":null,"abstract":"The ionic conductivity at the grain boundaries (GBs) in oxide ceramics is typically several orders of magnitude lower than that within the grain interior. This detrimental GB effect is the main bottleneck for designing high-performance ceramic electrolytes intended for use in solid-state lithium-ion batteries, fuel cells, and electrolyzer cells. The macroscopic ionic conductivity in oxide ceramics is essentially governed by the underlying polycrystalline microstructures where GBs and grain morphology go hand in hand. This provides the possibility to enhance the ion conductivity by microstructure engineering. To this end, a thorough understanding of microstructure–property correlation is highly desirable. In this work, we investigate numerous polycrystalline microstructure samples with varying grain and grain boundary features. Their macroscopic ionic conductivities are numerically evaluated by the finite element homogenization method, whereby the GB resistance is explicitly regarded. The influence of different microstructural features on the effective ionic conductivity is systematically studied. The microstructure–property relationships are revealed. Additionally, a graph neural network-based machine learning model is constructed and trained. It can accurately predict the effective ionic conductivity for a given polycrystalline microstructure. This work provides crucial quantitative guidelines for optimizing the ionic conducting performance of oxide ceramics by tailoring microstructures.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"61 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-07Epub Date: 2024-09-04DOI: 10.1063/5.0218262
Stephanie N Kramer, Jeanpun Antarasen, Cole R Reinholt, Lydia Kisley
We present a comprehensive guide to light-sheet microscopy (LSM) to assist scientists in navigating the practical implementation of this microscopy technique. Emphasizing the applicability of LSM to image both static microscale and nanoscale features, as well as diffusion dynamics, we present the fundamental concepts of microscopy, progressing through beam profile considerations, to image reconstruction. We outline key practical decisions in constructing a home-built system and provide insight into the alignment and calibration processes. We briefly discuss the conditions necessary for constructing a continuous 3D image and introduce our home-built code for data analysis. By providing this guide, we aim to alleviate the challenges associated with designing and constructing LSM systems and offer scientists new to LSM a valuable resource in navigating this complex field.
{"title":"A practical guide to light-sheet microscopy for nanoscale imaging: Looking beyond the cell.","authors":"Stephanie N Kramer, Jeanpun Antarasen, Cole R Reinholt, Lydia Kisley","doi":"10.1063/5.0218262","DOIUrl":"10.1063/5.0218262","url":null,"abstract":"<p><p>We present a comprehensive guide to light-sheet microscopy (LSM) to assist scientists in navigating the practical implementation of this microscopy technique. Emphasizing the applicability of LSM to image both static microscale and nanoscale features, as well as diffusion dynamics, we present the fundamental concepts of microscopy, progressing through beam profile considerations, to image reconstruction. We outline key practical decisions in constructing a home-built system and provide insight into the alignment and calibration processes. We briefly discuss the conditions necessary for constructing a continuous 3D image and introduce our home-built code for data analysis. By providing this guide, we aim to alleviate the challenges associated with designing and constructing LSM systems and offer scientists new to LSM a valuable resource in navigating this complex field.</p>","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"136 9","pages":"091101"},"PeriodicalIF":2.7,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11380115/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142154063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Deep levels in the whole bandgap of 4H-SiC generated by reactive ion etching (RIE) are investigated with both n- and p-type SiC Schottky barrier diodes by deep-level transient spectroscopy (DLTS). Depth profiles of the observed deep levels were analyzed using the DLTS peak intensities at various bias voltages and numerical calculations. The major electron traps detected after RIE and subsequent annealing at 1300 °C include the Z1/2 (EC−0.66 eV), ON1 (EC−0.88 eV), ON2 (EC−0.95 eV), and EH6/7 (EC−1.50 eV) centers, and the major hole traps include the UK1 (EV+0.51 eV), UK2 (EV+0.72 eV), HK0 (EV+0.77 eV), HK2 (EV+0.79 eV), and HK3 (EV+1.31 eV) centers, where EC and EV denote the conduction and valence band edges, respectively. Most of the traps were localized near the surface (<0.5 μm) with a maximum density of about 1×1015 cm−3, but several traps such as the ON1 and HK0 centers penetrate deep into the bulk region (>2 μm). By annealing at 1400 °C, most of the hole traps were eliminated, but several electron traps remained. From these results, the origins of these defects are discussed.
通过深电平瞬态光谱 (DLTS)，研究了反应离子蚀刻 (RIE) 在 n 型和 p 型 SiC 肖特基势垒二极管中产生的 4H-SiC 全带隙深电平。利用不同偏置电压下的 DLTS 峰强度和数值计算分析了观察到的深电平深度剖面。经过 RIE 和 1300 °C 退火后检测到的主要电子陷阱包括 Z1/2（EC-0.66 eV）、ON1（EC-0.88 eV）、ON2（EC-0.95 eV）和 EH6/7（EC-1.50 eV）中心，而主要的空穴陷阱包括 UK1（EV+0.51 eV）、UK2（EV+0.72 eV）、HK0（EV+0.77 eV）、HK2（EV+0.79 eV）和 HK3（EV+1.31 eV）中心，其中 EC 和 EV 分别表示导带和价带边缘。大多数陷阱都集中在表面附近（<0.5 μm），最大密度约为 1×1015 cm-3，但也有几个陷阱，如 ON1 和 HK0 中心，深入到体层区域（>2 μm）。在 1400 °C 退火后，大部分空穴陷阱被消除，但仍有几个电子陷阱存在。根据这些结果，我们讨论了这些缺陷的起源。
{"title":"Depth profiles of electron and hole traps generated by reactive ion etching near the surface of 4H-SiC","authors":"Shota Kozakai, Haruki Fujii, Mitsuaki Kaneko, Tsunenobu Kimoto","doi":"10.1063/5.0221700","DOIUrl":"https://doi.org/10.1063/5.0221700","url":null,"abstract":"Deep levels in the whole bandgap of 4H-SiC generated by reactive ion etching (RIE) are investigated with both n- and p-type SiC Schottky barrier diodes by deep-level transient spectroscopy (DLTS). Depth profiles of the observed deep levels were analyzed using the DLTS peak intensities at various bias voltages and numerical calculations. The major electron traps detected after RIE and subsequent annealing at 1300 °C include the Z1/2 (EC−0.66 eV), ON1 (EC−0.88 eV), ON2 (EC−0.95 eV), and EH6/7 (EC−1.50 eV) centers, and the major hole traps include the UK1 (EV+0.51 eV), UK2 (EV+0.72 eV), HK0 (EV+0.77 eV), HK2 (EV+0.79 eV), and HK3 (EV+1.31 eV) centers, where EC and EV denote the conduction and valence band edges, respectively. Most of the traps were localized near the surface (&lt;0.5 μm) with a maximum density of about 1×1015 cm−3, but several traps such as the ON1 and HK0 centers penetrate deep into the bulk region (&gt;2 μm). By annealing at 1400 °C, most of the hole traps were eliminated, but several electron traps remained. From these results, the origins of these defects are discussed.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"43 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, we explore the physics and evaluate the merits of strain engineering in two-dimensional van der Waals semiconductor-based FETs (field-effect-transistors) using DFT (density functional theory) to determine the modulation of the channel material properties under strain, and subsequently, their effect on carrier transport properties, i.e., scattering rates, mobility, and then finally simulate and analyze dissipative current transport with a non-equilibrium Green's function–Poisson's equation self-consistent solver. The scattering model includes the effects of charged impurities, intrinsic phonons, and remote phonons as well as the screening effect due to charged carriers. Impact of strain engineering on contact resistance is also incorporated into the transport simulations to determine the potential performance enhancements using strain in practical devices. Based on the comprehensive simulation results, we identify the materials and strain configuration that provide the best improvement in performance. We demonstrate an ON-current gain of 43.3% in a biaxially compressively strained monolayer MoSe2 device achieved through unique valley-crossing. Furthermore, implications of strain engineering for emerging energy-efficient devices based on band-to-band tunneling and spintronics are evaluated to explore uncharted frontiers in beyond-CMOS electron devices.
{"title":"Strain engineering in 2D FETs: Physics, status, and prospects","authors":"Ankit Kumar, Lin Xu, Arnab Pal, Kunjesh Agashiwala, Kamyar Parto, Wei Cao, Kaustav Banerjee","doi":"10.1063/5.0211555","DOIUrl":"https://doi.org/10.1063/5.0211555","url":null,"abstract":"In this work, we explore the physics and evaluate the merits of strain engineering in two-dimensional van der Waals semiconductor-based FETs (field-effect-transistors) using DFT (density functional theory) to determine the modulation of the channel material properties under strain, and subsequently, their effect on carrier transport properties, i.e., scattering rates, mobility, and then finally simulate and analyze dissipative current transport with a non-equilibrium Green's function–Poisson's equation self-consistent solver. The scattering model includes the effects of charged impurities, intrinsic phonons, and remote phonons as well as the screening effect due to charged carriers. Impact of strain engineering on contact resistance is also incorporated into the transport simulations to determine the potential performance enhancements using strain in practical devices. Based on the comprehensive simulation results, we identify the materials and strain configuration that provide the best improvement in performance. We demonstrate an ON-current gain of 43.3% in a biaxially compressively strained monolayer MoSe2 device achieved through unique valley-crossing. Furthermore, implications of strain engineering for emerging energy-efficient devices based on band-to-band tunneling and spintronics are evaluated to explore uncharted frontiers in beyond-CMOS electron devices.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"9 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204317","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mochammad Yan Pandu Akbar, Syafitra Salam, Cristoph P. Grams, Markus Diantoro, Bambang Prijamboedi, Joachim Hemberger, Agustinus Agung Nugroho
The dynamics of spin and charge-ordered phases in La1.67Sr0.33NiO4 single crystal have been investigated using high-frequency dielectric spectroscopy. The measurements were carried out in frequencies between 0.156 and 316 MHz and temperatures from 50 to 320 K. The intrinsic part of the response by excluding the Maxwell–Wagner relaxation region is obtained below TSDW ∼ 120 K. The intrinsic frequency-dependent real dielectric constant ɛ′ and conductivity σ′ can be well described in terms of the constant phase element revealing a complex charge-hopping process. Our results are in agreement with the spin-density-wave puddles’ picture observed by the scanning micro-x-ray diffraction technique. These demonstrate that high-frequency dielectric spectroscopy can be utilized for investigating the various order phases in other transition metal oxides by considering their intrinsic responses.
我们使用高频介电光谱法研究了 La1.67Sr0.33NiO4 单晶中自旋和电荷有序相的动力学。测量在 0.156 至 316 MHz 的频率和 50 至 320 K 的温度范围内进行。通过排除麦克斯韦尔-瓦格纳弛豫区，得到了低于 TSDW ∼ 120 K 的固有响应部分。我们的研究结果与扫描微 X 射线衍射技术观察到的自旋密度波坑图像一致。这些结果表明，通过考虑其他过渡金属氧化物的固有响应，可以利用高频介电光谱来研究它们的各种有序相。
{"title":"Dielectric responses of spin-density wave in La1.67Sr0.33NiO4 single crystal","authors":"Mochammad Yan Pandu Akbar, Syafitra Salam, Cristoph P. Grams, Markus Diantoro, Bambang Prijamboedi, Joachim Hemberger, Agustinus Agung Nugroho","doi":"10.1063/5.0219900","DOIUrl":"https://doi.org/10.1063/5.0219900","url":null,"abstract":"The dynamics of spin and charge-ordered phases in La1.67Sr0.33NiO4 single crystal have been investigated using high-frequency dielectric spectroscopy. The measurements were carried out in frequencies between 0.156 and 316 MHz and temperatures from 50 to 320 K. The intrinsic part of the response by excluding the Maxwell–Wagner relaxation region is obtained below TSDW ∼ 120 K. The intrinsic frequency-dependent real dielectric constant ɛ′ and conductivity σ′ can be well described in terms of the constant phase element revealing a complex charge-hopping process. Our results are in agreement with the spin-density-wave puddles’ picture observed by the scanning micro-x-ray diffraction technique. These demonstrate that high-frequency dielectric spectroscopy can be utilized for investigating the various order phases in other transition metal oxides by considering their intrinsic responses.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"172 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kirstin Alberi, Chase Brooks, Ian Leahy, Stephan Lany
Three-dimensional topological semimetals are a class of electronic materials in which their bulk and surface states contain linear band touching nodes near the Fermi level. Like semiconductors, their properties will be affected by point and extended defects in their crystal structures, although the extent to which defects and disorders influence topological semimetals may differ in key ways due to their unique electronic structures. In this Tutorial, we provide an overview of the defects in topological semimetals, covering both computational and experimental methods for exploring defect-property relationships. We also include a discussion on open questions that still need to be explored further.
{"title":"Tutorial: Defects in topological semimetals","authors":"Kirstin Alberi, Chase Brooks, Ian Leahy, Stephan Lany","doi":"10.1063/5.0217533","DOIUrl":"https://doi.org/10.1063/5.0217533","url":null,"abstract":"Three-dimensional topological semimetals are a class of electronic materials in which their bulk and surface states contain linear band touching nodes near the Fermi level. Like semiconductors, their properties will be affected by point and extended defects in their crystal structures, although the extent to which defects and disorders influence topological semimetals may differ in key ways due to their unique electronic structures. In this Tutorial, we provide an overview of the defects in topological semimetals, covering both computational and experimental methods for exploring defect-property relationships. We also include a discussion on open questions that still need to be explored further.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"18 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204319","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
James G. Boyd, Dimitrios Loufakis, Jodie L. Lutkenhaus
The motion of ions in supercapacitor electrodes produces internal stresses that cause viscoelastic strains. In addition, stresses may be due to external forces applied to structural supercapacitors, which are multifunctional materials that simultaneously store energy and carry structural loads. There are currently no thermodynamics-based models for the coupled electro-chemo-viscoelastic response of electrodes. Here, the same thermodynamics model is used for both the viscoelastic response and the electrochemical response. This mathematical equivalence is a reference from which to study coupling between the viscoelastic and electrochemical responses. The model has two inputs (stress or strain and electric potential or specific charge) and two outputs (strain or stress and specific charge or electric potential). The coupling is studied by adding three constants in the free energy. The convexity of the free energy and the stability of the free response limit the magnitude of the coupling. The unit response matrix is derived, and results are given for the time and frequency domains. The effect of an applied potential on stress is shown to be much more significant than the converse effect. The model compares well to an experiment consisting of a cyclic electric current applied during stress relaxation.
{"title":"Coupled electro-chemo-viscoelastic constitutive model for a supercapacitor electrode","authors":"James G. Boyd, Dimitrios Loufakis, Jodie L. Lutkenhaus","doi":"10.1063/5.0209577","DOIUrl":"https://doi.org/10.1063/5.0209577","url":null,"abstract":"The motion of ions in supercapacitor electrodes produces internal stresses that cause viscoelastic strains. In addition, stresses may be due to external forces applied to structural supercapacitors, which are multifunctional materials that simultaneously store energy and carry structural loads. There are currently no thermodynamics-based models for the coupled electro-chemo-viscoelastic response of electrodes. Here, the same thermodynamics model is used for both the viscoelastic response and the electrochemical response. This mathematical equivalence is a reference from which to study coupling between the viscoelastic and electrochemical responses. The model has two inputs (stress or strain and electric potential or specific charge) and two outputs (strain or stress and specific charge or electric potential). The coupling is studied by adding three constants in the free energy. The convexity of the free energy and the stability of the free response limit the magnitude of the coupling. The unit response matrix is derived, and results are given for the time and frequency domains. The effect of an applied potential on stress is shown to be much more significant than the converse effect. The model compares well to an experiment consisting of a cyclic electric current applied during stress relaxation.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"18 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. S. Devapriya, Nair S. Aditya, Mahathi Kuchibhotla, Adekunle Olusola Adeyeye, Arabinda Haldar
We report the effect of thickness and width on the spin wave transport and dispersion characteristics of permalloy (Py) microstripes using analytical calculations and experiments. Py waveguides with widths ranging from 2 to 4 μm were fabricated for two different thicknesses: 5 and 20 nm. Our results show a notable increase in the group velocity of spin waves with greater thickness, showing a fourfold rise as the thickness increases. Additionally, the accessible frequency range expands from 0.6 to 2.5 GHz as the thickness increases. We find that the spin wave mode frequency is affected by both thickness and width, with a frequency shift of approximately 0.2 GHz observed when the width increases from 2 to 4 μm. Moreover, spin waves decay more rapidly in thinner films, with the decay length of 20 nm-thick waveguides being four times longer than that of 5 nm-thick waveguides. Thicker and wider waveguides provide a longer decay length, facilitating the transmission of information over longer distances without significant energy loss. Our study offers an understanding of the spin wave propagation in microstrip waveguides and its potential in the development of future magnonic devices.
{"title":"Effect of width and thickness on propagating spin waves in permalloy microstripe waveguides","authors":"M. S. Devapriya, Nair S. Aditya, Mahathi Kuchibhotla, Adekunle Olusola Adeyeye, Arabinda Haldar","doi":"10.1063/5.0223672","DOIUrl":"https://doi.org/10.1063/5.0223672","url":null,"abstract":"We report the effect of thickness and width on the spin wave transport and dispersion characteristics of permalloy (Py) microstripes using analytical calculations and experiments. Py waveguides with widths ranging from 2 to 4 μm were fabricated for two different thicknesses: 5 and 20 nm. Our results show a notable increase in the group velocity of spin waves with greater thickness, showing a fourfold rise as the thickness increases. Additionally, the accessible frequency range expands from 0.6 to 2.5 GHz as the thickness increases. We find that the spin wave mode frequency is affected by both thickness and width, with a frequency shift of approximately 0.2 GHz observed when the width increases from 2 to 4 μm. Moreover, spin waves decay more rapidly in thinner films, with the decay length of 20 nm-thick waveguides being four times longer than that of 5 nm-thick waveguides. Thicker and wider waveguides provide a longer decay length, facilitating the transmission of information over longer distances without significant energy loss. Our study offers an understanding of the spin wave propagation in microstrip waveguides and its potential in the development of future magnonic devices.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"48 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Batalioto, K. Parekh, G. Barbero, A. M. Figueiredo Neto
We study the impedance behavior of two ferrofluids, of a similar magnetic material, one constituted by spherical nanoparticles and the other constituted by cubes, both suspended in kerosene. The ferrofluid constituted by cubic nanoparticles has 10% doping of a rare earth ion. The samples were inserted between two parallel disk-like electrodes of area S=2.3cm2 made of surgical steel, separated by d=127μm. The impedance was measured by applying a sinusoidal voltage of amplitude V0=30 mV, from 1 mHz to 100 kHz. To analyze the experimental data, we use a model based on the Poisson–Nernst–Planck equations, with Ohmic boundary conditions. In the analysis, we assume that the ferrofluids contain free ions, originated from the manufacturing process, released by the stabilization layer around the magnetic nanoparticles dispersed in kerosene. The corresponding nanoparticles are charged of opposite signs with respect to these free ions. In the high frequency region, the effective diffusion coefficient coincides with that from the free diffusion coefficients, defined as the mathematical average between the diffusion coefficients of the nanoparticles and the free ions. In the low frequency region, we found the ambipolar diffusion coefficient, defined as their harmonic average. The effect of the electrodes is taken into account by means of surface conductivity to describe the conduction current across the electrode, assumed to be proportional to the surface electric field. In this model, the role of the electrodes is important just in the low frequency region. On the contrary, in the high frequency region, where the electric current is dominated by the displacement current, the role of the electrodes is negligible. The results show that the nanoparticles of the magnetic material have no effects on the higher-frequency range of the impedance spectra. In the low frequency region, our results indicate a difference in the electric response of the two ferrofluids. Due to their similar dimensions and, hence, similar ambipolar diffusion coefficients, we impute the observed different behavior to the charge transfer from the bulk to the external circuit included in the surface conductivity.
{"title":"Impedance measurements on kerosene-based ferrofluids","authors":"F. Batalioto, K. Parekh, G. Barbero, A. M. Figueiredo Neto","doi":"10.1063/5.0223322","DOIUrl":"https://doi.org/10.1063/5.0223322","url":null,"abstract":"We study the impedance behavior of two ferrofluids, of a similar magnetic material, one constituted by spherical nanoparticles and the other constituted by cubes, both suspended in kerosene. The ferrofluid constituted by cubic nanoparticles has 10% doping of a rare earth ion. The samples were inserted between two parallel disk-like electrodes of area S=2.3cm2 made of surgical steel, separated by d=127μm. The impedance was measured by applying a sinusoidal voltage of amplitude V0=30 mV, from 1 mHz to 100 kHz. To analyze the experimental data, we use a model based on the Poisson–Nernst–Planck equations, with Ohmic boundary conditions. In the analysis, we assume that the ferrofluids contain free ions, originated from the manufacturing process, released by the stabilization layer around the magnetic nanoparticles dispersed in kerosene. The corresponding nanoparticles are charged of opposite signs with respect to these free ions. In the high frequency region, the effective diffusion coefficient coincides with that from the free diffusion coefficients, defined as the mathematical average between the diffusion coefficients of the nanoparticles and the free ions. In the low frequency region, we found the ambipolar diffusion coefficient, defined as their harmonic average. The effect of the electrodes is taken into account by means of surface conductivity to describe the conduction current across the electrode, assumed to be proportional to the surface electric field. In this model, the role of the electrodes is important just in the low frequency region. On the contrary, in the high frequency region, where the electric current is dominated by the displacement current, the role of the electrodes is negligible. The results show that the nanoparticles of the magnetic material have no effects on the higher-frequency range of the impedance spectra. In the low frequency region, our results indicate a difference in the electric response of the two ferrofluids. Due to their similar dimensions and, hence, similar ambipolar diffusion coefficients, we impute the observed different behavior to the charge transfer from the bulk to the external circuit included in the surface conductivity.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"1 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zeldovich amplification of classic waves carrying orbital angular momentum (OAM) from a rotating absorber is an extension of Penrose superradiance from a rotating black hole. The demonstration of Zeldovich amplification in recently published experiments showed the possibility of extracting energy from a spinning black hole or a rotating absorber. However, it remains unclear whether extracting energy from non-absorbent bodies is possible. Here, we experimentally demonstrate the amplification of acoustic OAM from rotating impellers made of non-absorbent materials. We develop a multichannel least-mean-square algorithm to emit high-charge acoustic OAM beams into three types of impellers. The acoustic gains (more than 20 dB) have been measured by both a static microphone and a microphone array working as a virtual rotating receiver. The results indicate that the acoustic gain from the impeller with a large windward area is much higher than the ones with a small area. Our work is worthwhile in proposing the experimental method to study the phenomenon of acoustic OAM amplification and showing prospects in industrial applications such as amplifying acoustic signals by commonly used impellers. Our work also discusses a possible way of extracting energy from non-absorbent celestial systems, such as the orbiting planets of the Solar system, which are much less absorbent to light but much closer to the Earth than a black hole.
{"title":"Amplification of acoustic orbital angular momentum from non-absorbent impellers","authors":"Lianyun Liu, Zhigang Chu","doi":"10.1063/5.0218404","DOIUrl":"https://doi.org/10.1063/5.0218404","url":null,"abstract":"Zeldovich amplification of classic waves carrying orbital angular momentum (OAM) from a rotating absorber is an extension of Penrose superradiance from a rotating black hole. The demonstration of Zeldovich amplification in recently published experiments showed the possibility of extracting energy from a spinning black hole or a rotating absorber. However, it remains unclear whether extracting energy from non-absorbent bodies is possible. Here, we experimentally demonstrate the amplification of acoustic OAM from rotating impellers made of non-absorbent materials. We develop a multichannel least-mean-square algorithm to emit high-charge acoustic OAM beams into three types of impellers. The acoustic gains (more than 20 dB) have been measured by both a static microphone and a microphone array working as a virtual rotating receiver. The results indicate that the acoustic gain from the impeller with a large windward area is much higher than the ones with a small area. Our work is worthwhile in proposing the experimental method to study the phenomenon of acoustic OAM amplification and showing prospects in industrial applications such as amplifying acoustic signals by commonly used impellers. Our work also discusses a possible way of extracting energy from non-absorbent celestial systems, such as the orbiting planets of the Solar system, which are much less absorbent to light but much closer to the Earth than a black hole.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":"403 1","pages":""},"PeriodicalIF":3.2,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142204321","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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