Dongpeng Zhao, Jun Li, H. Bai, Huantong Wu, Xiping Chen, Guangai Sun, Zhongxiang Zhou
Consistent c-axis orientation characteristics toward the direction of applied pressure of Y-type BaSrCo2Fe11AlO22 (BSCFAO-θ) were successfully prepared by the strategy of hot pressing. The samples’ magnetoelectric coupling performance was greatly enhanced by the strategy of hot pressing than that of the traditional solid reaction method. The magnetoelectric current of BSCFAO-θ (θ = 0°) (12.06 μA/m2) was nearly 5 times higher than BSCFAO-SS (2.24 μA/m2). The magnetoelectric polarization of BSCFAO-θ (θ = 0°) (32.82 μC/m2) was nearly 4 times higher than that of BSCFAO-SS (8.31 μC/m2). The magnetoelectric coupling coefficients of BSCFAO-θ (θ = 0°) (1880 ps/m) were nearly 4 times higher than those of BSCFAO-SS (404 ps/m). The enhancement of magnetoelectric polarization of BSCFAO-θ (θ = 0°) can be attributed to the uniform c-axis orientation, which reinforced magnetoelectric polarization compared with none orientation that eliminated the magnetoelectric polarization on grain boundaries. The magnetoelectric coupling performance of BSCFAO-θ presented a gradually decreasing trend with the angle changing from 0° to 90° for the changing of orientation. Compared with traditional solid reaction methods, the strategy of hot pressing inhibits grain growth and increases grain boundaries, thus facilitating the enhancement of grain boundaries’ resistivity, and the electrical resistivity of BSCFAO-θ (3.08 × 1010 Ω cm) was nearly 10 000 times higher than that of BSCFAO-SS (2.5 × 106 Ω cm), which also benefits the magnetoelectric polarization performance of BSCFAO-θ. Therefore, the hot-pressing strategy can contribute to the forming of oriented ceramics and enhance the grain boundaries’ resistivity to improve magnetoelectric coupling performance.
{"title":"Consistent c-axis orientation and reinforced magnetoelectric coupling performance in bulk BaSrCo2Fe11AlO22","authors":"Dongpeng Zhao, Jun Li, H. Bai, Huantong Wu, Xiping Chen, Guangai Sun, Zhongxiang Zhou","doi":"10.1063/5.0198180","DOIUrl":"https://doi.org/10.1063/5.0198180","url":null,"abstract":"Consistent c-axis orientation characteristics toward the direction of applied pressure of Y-type BaSrCo2Fe11AlO22 (BSCFAO-θ) were successfully prepared by the strategy of hot pressing. The samples’ magnetoelectric coupling performance was greatly enhanced by the strategy of hot pressing than that of the traditional solid reaction method. The magnetoelectric current of BSCFAO-θ (θ = 0°) (12.06 μA/m2) was nearly 5 times higher than BSCFAO-SS (2.24 μA/m2). The magnetoelectric polarization of BSCFAO-θ (θ = 0°) (32.82 μC/m2) was nearly 4 times higher than that of BSCFAO-SS (8.31 μC/m2). The magnetoelectric coupling coefficients of BSCFAO-θ (θ = 0°) (1880 ps/m) were nearly 4 times higher than those of BSCFAO-SS (404 ps/m). The enhancement of magnetoelectric polarization of BSCFAO-θ (θ = 0°) can be attributed to the uniform c-axis orientation, which reinforced magnetoelectric polarization compared with none orientation that eliminated the magnetoelectric polarization on grain boundaries. The magnetoelectric coupling performance of BSCFAO-θ presented a gradually decreasing trend with the angle changing from 0° to 90° for the changing of orientation. Compared with traditional solid reaction methods, the strategy of hot pressing inhibits grain growth and increases grain boundaries, thus facilitating the enhancement of grain boundaries’ resistivity, and the electrical resistivity of BSCFAO-θ (3.08 × 1010 Ω cm) was nearly 10 000 times higher than that of BSCFAO-SS (2.5 × 106 Ω cm), which also benefits the magnetoelectric polarization performance of BSCFAO-θ. Therefore, the hot-pressing strategy can contribute to the forming of oriented ceramics and enhance the grain boundaries’ resistivity to improve magnetoelectric coupling performance.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674065","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}
S. Jena, R. Urkude, W.-Y. Choi, K. K. Pandey, S. Karwal, M. Jung, J. Gardner, B. Ghosh, V. R. Singh
Magnetic nanometric skyrmions are small complex vortex-like topological defects, mainly found in non-centrosymmetric crystals such as MnSi. They have potential applications for future spintronic devices. In this article, the structural, electronic, and magnetic states of the Mn atoms in a polycrystalline MnSi thin film facing a c-sapphire substrate were studied using x-ray diffraction, x-ray photo-emission spectroscopy, resonance photoemission spectroscopy (RPES), and extended x-ray absorption fine structure (EXAFS). The valence band spectra indicate the metallic nature of the film. The RPES study reveals the presence of major itinerant Mn 3d states near EF and also the mixed Mn 3d and Si 3s–3p states from 5.3 to 11.3 eV. The EXAFS spectrum does not show the existence of oxygen vacancies in the system, and the obtained magnetic moment in the non-stoichiometric MnSi thin film is a combination of the partially itinerant and partially localized Mn 3d states.
磁性纳米天幕是一种小型复杂的涡旋状拓扑缺陷，主要存在于锰硅等非中心对称晶体中。它们有可能应用于未来的自旋电子器件。本文利用 X 射线衍射、X 射线光发射光谱、共振光发射光谱（RPES）和扩展 X 射线吸收精细结构（EXAFS）研究了面向 c 蓝宝石衬底的多晶锰硅薄膜中锰原子的结构、电子和磁态。价带光谱显示了薄膜的金属性质。共振光发射光谱研究显示，在 EF 附近存在主要的锰 3d 流动态，在 5.3 至 11.3 eV 之间还存在锰 3d 和硅 3s-3p 混合态。EXAFS 光谱没有显示出系统中存在氧空位，而在非化学计量锰硅薄膜中获得的磁矩是部分巡回态和部分局部态 Mn 3d 的组合。
{"title":"Electronic structures of skyrmionic polycrystalline MnSi thin film studied by resonance photoemission and x-ray near edge spectroscopy","authors":"S. Jena, R. Urkude, W.-Y. Choi, K. K. Pandey, S. Karwal, M. Jung, J. Gardner, B. Ghosh, V. R. Singh","doi":"10.1063/5.0202229","DOIUrl":"https://doi.org/10.1063/5.0202229","url":null,"abstract":"Magnetic nanometric skyrmions are small complex vortex-like topological defects, mainly found in non-centrosymmetric crystals such as MnSi. They have potential applications for future spintronic devices. In this article, the structural, electronic, and magnetic states of the Mn atoms in a polycrystalline MnSi thin film facing a c-sapphire substrate were studied using x-ray diffraction, x-ray photo-emission spectroscopy, resonance photoemission spectroscopy (RPES), and extended x-ray absorption fine structure (EXAFS). The valence band spectra indicate the metallic nature of the film. The RPES study reveals the presence of major itinerant Mn 3d states near EF and also the mixed Mn 3d and Si 3s–3p states from 5.3 to 11.3 eV. The EXAFS spectrum does not show the existence of oxygen vacancies in the system, and the obtained magnetic moment in the non-stoichiometric MnSi thin film is a combination of the partially itinerant and partially localized Mn 3d states.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140676297","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}
C. Le Bras, L. Berthe, L. Videau, S. Baton, M. Boustie, S. Boyer, C. Rousseaux, E. Brambrink, J M Chevalier, J. Houy, B. Aubert, B. Jodar, D. Loison, D. Hébert
Laser ablation propulsion and orbit cleaning are developing areas of research. The general aim of laser-based techniques applied to this field is to maximize the momentum transfer produced by a laser shot. This work presents results from ballistic pendulum experiments under vacuum on aluminum, copper, tin, gold, and porous graphite targets. The work has focused on the metrology of the laser experiments to ensure good stability over a wide range of laser parameters (laser intensity ranging from 4 GW/cm2 to 8.7 TW/cm2, pulse duration from 80 ps to 15 ns, and wavelengths of 528 or 1057 nm). The results presented compile data from three experimental campaigns spanning from 2018 to 2021 on two different laser platforms and using different pulse durations, energies, and wavelengths. The study is complemented by the simulation of the momentum from the mono-dimensional Lagrangian code ESTHER. The first part of this work gives a detailed description of the experimental setup used, the ESTHER code, and the treatment of the simulations. The second part focuses on the experimental results. The third part describes the simulation results and provides a comparison with the experimental data. The last part presents possible improvements for future work on the subject.
{"title":"Impulse coupling measurement of metallic and carbon targets during laser ablation through ballistic pendulum experiments and simulations","authors":"C. Le Bras, L. Berthe, L. Videau, S. Baton, M. Boustie, S. Boyer, C. Rousseaux, E. Brambrink, J M Chevalier, J. Houy, B. Aubert, B. Jodar, D. Loison, D. Hébert","doi":"10.1063/5.0201435","DOIUrl":"https://doi.org/10.1063/5.0201435","url":null,"abstract":"Laser ablation propulsion and orbit cleaning are developing areas of research. The general aim of laser-based techniques applied to this field is to maximize the momentum transfer produced by a laser shot. This work presents results from ballistic pendulum experiments under vacuum on aluminum, copper, tin, gold, and porous graphite targets. The work has focused on the metrology of the laser experiments to ensure good stability over a wide range of laser parameters (laser intensity ranging from 4 GW/cm2 to 8.7 TW/cm2, pulse duration from 80 ps to 15 ns, and wavelengths of 528 or 1057 nm). The results presented compile data from three experimental campaigns spanning from 2018 to 2021 on two different laser platforms and using different pulse durations, energies, and wavelengths. The study is complemented by the simulation of the momentum from the mono-dimensional Lagrangian code ESTHER. The first part of this work gives a detailed description of the experimental setup used, the ESTHER code, and the treatment of the simulations. The second part focuses on the experimental results. The third part describes the simulation results and provides a comparison with the experimental data. The last part presents possible improvements for future work on the subject.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140673808","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}
Thorium nitrides have been the topic of intense studies due to their prospective applications as advanced nuclear fuels. The phase diagram of the Th–N scheme, however, continues unknown at low temperatures and extremely high pressures. In this article, we examine the Th–N system's phase diagram up to 300 GPa from the first-principle approach using universal structure predictor: evolutionary Xtallography (USPEX) method. Apart from the experimentally observed phase (ThN, Th2N3, and Th3N4), there are several unique chemical stoichiometries, i.e., ThN3, ThN4, ThN6, ThN8, ThN10, and ThN12 are found to have stability fields on the Th–N phase diagram at pressure of 3.0, 32, 100, 42, 28, and 236 GPa along with previously predicted composition ThN2 at 3.5 GPa. The structural stability of the predicted compositions is further assessed by evaluating the elastic and dynamic stability. Out of all above mentioned compositions, ThN3 is possibly a metastable one at 0 GPa. Electronic structure calculations predict that all newly discovered compositions are metallic except ThN10, which is semi-metallic at high pressures. Further, we predict that ThN4 and ThN6 have high electron–phonon coupling constant of 1.874 and 0.894 with Tc around 21.22 and 25.02 K, respectively, at 100 GPa.
{"title":"Predictions of thorium super nitrides and superconductivity under pressure: Ab initio calculations","authors":"B. Sahoo, K. Joshi","doi":"10.1063/5.0206354","DOIUrl":"https://doi.org/10.1063/5.0206354","url":null,"abstract":"Thorium nitrides have been the topic of intense studies due to their prospective applications as advanced nuclear fuels. The phase diagram of the Th–N scheme, however, continues unknown at low temperatures and extremely high pressures. In this article, we examine the Th–N system's phase diagram up to 300 GPa from the first-principle approach using universal structure predictor: evolutionary Xtallography (USPEX) method. Apart from the experimentally observed phase (ThN, Th2N3, and Th3N4), there are several unique chemical stoichiometries, i.e., ThN3, ThN4, ThN6, ThN8, ThN10, and ThN12 are found to have stability fields on the Th–N phase diagram at pressure of 3.0, 32, 100, 42, 28, and 236 GPa along with previously predicted composition ThN2 at 3.5 GPa. The structural stability of the predicted compositions is further assessed by evaluating the elastic and dynamic stability. Out of all above mentioned compositions, ThN3 is possibly a metastable one at 0 GPa. Electronic structure calculations predict that all newly discovered compositions are metallic except ThN10, which is semi-metallic at high pressures. Further, we predict that ThN4 and ThN6 have high electron–phonon coupling constant of 1.874 and 0.894 with Tc around 21.22 and 25.02 K, respectively, at 100 GPa.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140674600","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}
B. R. Moya, A. C. Iglesias-Jaime, A. C. Silva, A. Peláiz‐Barranco, J. D. S. Guerra
(Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics were synthesized via the conventional solid-state reaction method. Structural and dielectric properties were investigated as a function of the doping concentration, considering x = 0, 2, 5, 8, 10, 12, 16, and 18 at. % Ba. The structural analyses were carried out from the x-ray diffraction technique, including the Rietveld refinement method, and Raman spectroscopy. Results confirmed the formation of the perovskite structure, revealing different crystalline symmetries, depending on the Ba2+ concentration: the single rhombohedral ferroelectric phase (R3c) for x = 0 and 2 at. %; coexistence of both rhombohedral ferroelectric (R3c) and tetragonal antiferroelectric (P4bm) phases for x = 5 at. % Ba; the single tetragonal antiferroelectric phase (P4bm) for x = 8 at. % Ba; coexistence of two tetragonal phases (antiferroelectric P4bm and ferroelectric P4mm) for x = 10 at. % Ba; and the single tetragonal ferroelectric phase (P4mm) for x = 12, 16, and 18 at. % Ba. The characteristics of the phases’ transition, investigated from dielectric analysis, revealed the presence of two dielectric anomalies, which indeed have been associated to different phases’ transitions, one of them showing relaxor-like characteristics. The obtained results offer new insights for a better understanding on the features of the phase diagram for the studied ceramic system, according to the different observed crystalline symmetries (ferroelectric and antiferroelectric) in a very wide doping concentration. In the light of the obtained results, a new phase diagram has been proposed considering a wider compositional range than those reported in the literature.
{"title":"Structural and dielectric features of (Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics: An approach to the phase diagram","authors":"B. R. Moya, A. C. Iglesias-Jaime, A. C. Silva, A. Peláiz‐Barranco, J. D. S. Guerra","doi":"10.1063/5.0191402","DOIUrl":"https://doi.org/10.1063/5.0191402","url":null,"abstract":"(Bi0.5Na0.5)1−xBaxTiO3 lead-free ferroelectric ceramics were synthesized via the conventional solid-state reaction method. Structural and dielectric properties were investigated as a function of the doping concentration, considering x = 0, 2, 5, 8, 10, 12, 16, and 18 at. % Ba. The structural analyses were carried out from the x-ray diffraction technique, including the Rietveld refinement method, and Raman spectroscopy. Results confirmed the formation of the perovskite structure, revealing different crystalline symmetries, depending on the Ba2+ concentration: the single rhombohedral ferroelectric phase (R3c) for x = 0 and 2 at. %; coexistence of both rhombohedral ferroelectric (R3c) and tetragonal antiferroelectric (P4bm) phases for x = 5 at. % Ba; the single tetragonal antiferroelectric phase (P4bm) for x = 8 at. % Ba; coexistence of two tetragonal phases (antiferroelectric P4bm and ferroelectric P4mm) for x = 10 at. % Ba; and the single tetragonal ferroelectric phase (P4mm) for x = 12, 16, and 18 at. % Ba. The characteristics of the phases’ transition, investigated from dielectric analysis, revealed the presence of two dielectric anomalies, which indeed have been associated to different phases’ transitions, one of them showing relaxor-like characteristics. The obtained results offer new insights for a better understanding on the features of the phase diagram for the studied ceramic system, according to the different observed crystalline symmetries (ferroelectric and antiferroelectric) in a very wide doping concentration. In the light of the obtained results, a new phase diagram has been proposed considering a wider compositional range than those reported in the literature.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140672971","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}
Zeqing Yu, X. Hou, Sizheng Zheng, Chen Bin, Jieying Wang
The solid-state refrigeration technique based on the electrocaloric effect (ECE) of ferroelectric materials has been regarded as a promising alternative to vapor compression systems due to its advantages of high efficiency and easy miniaturization. However, the small adiabatic temperature change (ATC) and narrow operating temperature range of ferroelectric materials are key obstacles for their practical applications of ECE refrigeration. To improve the ECE performance of ferroelectric polymer poly(vinylidene fluoride) [P(VDF-TrFE)], PbZr1−xTixO3 (PZT) nanoparticles with larger polarization is herein introduced to form ferroelectric nanocomposites. The phase-field simulation is employed to investigate the dynamic hysteresis loops and corresponding domain evolution of the ferroelectric nanocomposites. The temperature-dependent ATC values are calculated using the indirect method based on the Maxwell relation. The appearance of the double hysteresis loop is observed in P(VDF-TrFE) nanocomposite filled with PbZr0.1Ti0.9O3 nanoparticles [P(VDF-TrFE)–PZT0.9], which is mainly caused by a microscopic domain transition from single domain to polar vortex. Compared to the P(VDF-TrFE), enhanced ATC values associated with the domain transition are unveiled in P(VDF-TrFE)–PZT0.9, and the temperature range of excellent ECE is also effectively broadened. In addition, as the component x of filled PZT nanoparticles increases to cross the morphotropic phase boundary (MPB), the maximum ATC value shows a significant increase. The results presented in this work not only explain the mechanism of domain transition induced excellent ECE in the P(VDF-TrFE)–PZT nanocomposite, but also stimulate future studies on enhancing ECE of P(VDF-TrFE) by introducing ferroelectric nanofillers.
{"title":"Large electrocaloric effect near room temperature induced by domain switching in ferroelectric nanocomposites","authors":"Zeqing Yu, X. Hou, Sizheng Zheng, Chen Bin, Jieying Wang","doi":"10.1063/5.0205338","DOIUrl":"https://doi.org/10.1063/5.0205338","url":null,"abstract":"The solid-state refrigeration technique based on the electrocaloric effect (ECE) of ferroelectric materials has been regarded as a promising alternative to vapor compression systems due to its advantages of high efficiency and easy miniaturization. However, the small adiabatic temperature change (ATC) and narrow operating temperature range of ferroelectric materials are key obstacles for their practical applications of ECE refrigeration. To improve the ECE performance of ferroelectric polymer poly(vinylidene fluoride) [P(VDF-TrFE)], PbZr1−xTixO3 (PZT) nanoparticles with larger polarization is herein introduced to form ferroelectric nanocomposites. The phase-field simulation is employed to investigate the dynamic hysteresis loops and corresponding domain evolution of the ferroelectric nanocomposites. The temperature-dependent ATC values are calculated using the indirect method based on the Maxwell relation. The appearance of the double hysteresis loop is observed in P(VDF-TrFE) nanocomposite filled with PbZr0.1Ti0.9O3 nanoparticles [P(VDF-TrFE)–PZT0.9], which is mainly caused by a microscopic domain transition from single domain to polar vortex. Compared to the P(VDF-TrFE), enhanced ATC values associated with the domain transition are unveiled in P(VDF-TrFE)–PZT0.9, and the temperature range of excellent ECE is also effectively broadened. In addition, as the component x of filled PZT nanoparticles increases to cross the morphotropic phase boundary (MPB), the maximum ATC value shows a significant increase. The results presented in this work not only explain the mechanism of domain transition induced excellent ECE in the P(VDF-TrFE)–PZT nanocomposite, but also stimulate future studies on enhancing ECE of P(VDF-TrFE) by introducing ferroelectric nanofillers.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140677167","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 illustrates the successful achievement of tunable defect bands in one-dimensional defective phononic crystals (PnCs) through the incorporation of piezoelectric defects with synthetic negative capacitances (SNCs) for the first time. The efficacy of SNCs in creating tunable bandpass filters across a broad frequency range is thoroughly examined using the proposed analytical and numerical models. A newly developed electroelastically coupled transfer matrix that incorporates SNCs is presented, considering either series or parallel connection between bimorph piezoelectric elements. Defect band and transmittance analyses are conducted using the transfer matrix and S-parameter methods. Two key findings emerge from this investigation. First, when the total equivalent capacitance of the bimorph piezoelectric elements and SNC becomes zero, the defect band representing the point-symmetric defect-mode shape can be customized throughout the entire phononic bandgap. Second, the constant transmittance value, resembling short-circuit conditions, highlights the remarkable ability of SNCs to tune defect bands without energy dissipation, paving the way for fully tunable bandpass filters. To propel this research forward, future investigations could explore expanding the design space with double defects, adopting enhanced modeling techniques to account for lateral and shear effects, developing a control algorithm for the automatic optimization of SNC values in actively tunable bandpass filters, and incorporating artificial intelligence into design methods for piezoelectric defects with electrical connections.
{"title":"Tunable bandpass filters using a defective phononic crystal shunted to synthetic negative capacitance for longitudinal waves","authors":"Soo-Ho Jo, Moonsu Park, Minseo Kim, Jeonggyu Yang","doi":"10.1063/5.0203514","DOIUrl":"https://doi.org/10.1063/5.0203514","url":null,"abstract":"This study illustrates the successful achievement of tunable defect bands in one-dimensional defective phononic crystals (PnCs) through the incorporation of piezoelectric defects with synthetic negative capacitances (SNCs) for the first time. The efficacy of SNCs in creating tunable bandpass filters across a broad frequency range is thoroughly examined using the proposed analytical and numerical models. A newly developed electroelastically coupled transfer matrix that incorporates SNCs is presented, considering either series or parallel connection between bimorph piezoelectric elements. Defect band and transmittance analyses are conducted using the transfer matrix and S-parameter methods. Two key findings emerge from this investigation. First, when the total equivalent capacitance of the bimorph piezoelectric elements and SNC becomes zero, the defect band representing the point-symmetric defect-mode shape can be customized throughout the entire phononic bandgap. Second, the constant transmittance value, resembling short-circuit conditions, highlights the remarkable ability of SNCs to tune defect bands without energy dissipation, paving the way for fully tunable bandpass filters. To propel this research forward, future investigations could explore expanding the design space with double defects, adopting enhanced modeling techniques to account for lateral and shear effects, developing a control algorithm for the automatic optimization of SNC values in actively tunable bandpass filters, and incorporating artificial intelligence into design methods for piezoelectric defects with electrical connections.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140677856","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}
Neha Yadav, Suraj Kumar, A. Choudhary, Anil K. Thakur, Rajesh, Surinder P. Singh, A. Biradar
High tilt angle (45°) ferroelectric liquid crystal (FLC) in surface stabilized geometry, having no chiral smectic A (SmA∗) phase, has been studied for the reorientation of the smectic layers near the transition temperature (Tc). The electro-optical studies have shown the stripe domain formation in which the liquid crystal molecules are aligned along the rubbing direction, but the smectic layers are tilted away from the rubbing direction at room temperature. In such high tilt angle FLCs, the molecular alignment and smectic layer formation start from bottom and top rubbed grooves at Tc. The domain formation of the FLC takes place in the middle of the top and bottom surfaces due to the frustration of the dipolar interaction. The smectic layer switching is observed by optical microscopy and confirmed by the dielectric spectroscopy method near Tc of SmC∗ and chiral nematic phases. Domain switching has shown a larger switching angle than the molecular tilt angle within the smectic layer. These studies are expected to be significant for understanding the smectic layer structure and the domain switching process, which may pave the way for large optical switching devices.
{"title":"Domain reorientation due to smectic layer instability in high tilt angle-based surface stabilized ferroelectric liquid crystal cell","authors":"Neha Yadav, Suraj Kumar, A. Choudhary, Anil K. Thakur, Rajesh, Surinder P. Singh, A. Biradar","doi":"10.1063/5.0198434","DOIUrl":"https://doi.org/10.1063/5.0198434","url":null,"abstract":"High tilt angle (45°) ferroelectric liquid crystal (FLC) in surface stabilized geometry, having no chiral smectic A (SmA∗) phase, has been studied for the reorientation of the smectic layers near the transition temperature (Tc). The electro-optical studies have shown the stripe domain formation in which the liquid crystal molecules are aligned along the rubbing direction, but the smectic layers are tilted away from the rubbing direction at room temperature. In such high tilt angle FLCs, the molecular alignment and smectic layer formation start from bottom and top rubbed grooves at Tc. The domain formation of the FLC takes place in the middle of the top and bottom surfaces due to the frustration of the dipolar interaction. The smectic layer switching is observed by optical microscopy and confirmed by the dielectric spectroscopy method near Tc of SmC∗ and chiral nematic phases. Domain switching has shown a larger switching angle than the molecular tilt angle within the smectic layer. These studies are expected to be significant for understanding the smectic layer structure and the domain switching process, which may pave the way for large optical switching devices.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140703477","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 lattice thermal conductivity stands as a pivotal thermos-physical parameter of high-entropy alloys; nonetheless, achieving precise predictions of the lattice thermal conductivity for high-entropy alloys poses a formidable challenge due to their complex composition and structure. In this study, machine learning models were built to predict the lattice thermal conductivity of AlCoCrNiFe high-entropy alloy based on molecular dynamic simulations. Our model shows high accuracy with R2, mean absolute percentage error, and root mean square error of the test set is 0.91, 0.031, and 1.128 W m−1 k−1, respectively. In addition, a high-entropy alloy with low a lattice thermal conductivity of 2.06 W m−1 k−1 (Al8Cr30Co19Ni20Fe23) and with a high lattice thermal conductivity of 5.29 W m−1 k−1 (Al0.5Cr28.5Co25Ni25.5Fe20.5) was successfully predicted, which shows good agreement with the results from molecular dynamics simulations. The mechanisms of the thermal conductivity divergence are further explained through their phonon density of states and elastic modulus. The established model provides a powerful tool for developing high-entropy alloys with the desired properties.
晶格热导率是高熵合金的一个关键热物理参数；然而，由于高熵合金的成分和结构复杂，要精确预测其晶格热导率是一项艰巨的挑战。本研究基于分子动力学模拟，建立了机器学习模型来预测 AlCoCrNiFe 高熵合金的晶格热导率。我们的模型具有很高的准确性，测试集的 R2、平均绝对百分比误差和均方根误差分别为 0.91、0.031 和 1.128 W m-1 k-1。此外，还成功预测了低晶格热导率为 2.06 W m-1 k-1 （Al8Cr30Co19Ni20Fe23）和高晶格热导率为 5.29 W m-1 k-1 （Al0.5Cr28.5Co25Ni25.5Fe20.5）的高熵合金，这与分子动力学模拟的结果显示出良好的一致性。通过声子态密度和弹性模量，进一步解释了热导率差异的机理。所建立的模型为开发具有所需性能的高熵合金提供了强有力的工具。
{"title":"Estimating the lattice thermal conductivity of AlCoCrNiFe high-entropy alloy using machine learning","authors":"Jie Lu, Xiaona Huang, Y. Yue","doi":"10.1063/5.0201042","DOIUrl":"https://doi.org/10.1063/5.0201042","url":null,"abstract":"The lattice thermal conductivity stands as a pivotal thermos-physical parameter of high-entropy alloys; nonetheless, achieving precise predictions of the lattice thermal conductivity for high-entropy alloys poses a formidable challenge due to their complex composition and structure. In this study, machine learning models were built to predict the lattice thermal conductivity of AlCoCrNiFe high-entropy alloy based on molecular dynamic simulations. Our model shows high accuracy with R2, mean absolute percentage error, and root mean square error of the test set is 0.91, 0.031, and 1.128 W m−1 k−1, respectively. In addition, a high-entropy alloy with low a lattice thermal conductivity of 2.06 W m−1 k−1 (Al8Cr30Co19Ni20Fe23) and with a high lattice thermal conductivity of 5.29 W m−1 k−1 (Al0.5Cr28.5Co25Ni25.5Fe20.5) was successfully predicted, which shows good agreement with the results from molecular dynamics simulations. The mechanisms of the thermal conductivity divergence are further explained through their phonon density of states and elastic modulus. The established model provides a powerful tool for developing high-entropy alloys with the desired properties.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140748721","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}
An analytical device physics model is presented for determining the energy conversion efficiency of semiconductor nanowire array-based radial (core–shell) p-i-n junction betavoltaic cells for two- and three-dimensional radioisotope source geometries. Optimum short-circuit current density Jsc, open-circuit voltage Voc, fill factor FF, and energy conversion efficiency η are determined for various nanowire properties, including dopant concentration, nanowire length, core diameter, and shell thickness, for Si, GaAs, and GaP material systems. A maximum efficiency of 8.05% was obtained for GaP nanowires with diameter 200nm (p-core diameter, i-shell, and n-shell thicknesses of 24, 29.4, and 58.6 nm, respectively), length 10μm, acceptor and donor concentrations of 1019 and 5×1018cm−3, respectively, and a 3D source geometry.
{"title":"Analytical model of a nanowire-based betavoltaic device","authors":"Amanda Thomas, R. LaPierre","doi":"10.1063/5.0202949","DOIUrl":"https://doi.org/10.1063/5.0202949","url":null,"abstract":"An analytical device physics model is presented for determining the energy conversion efficiency of semiconductor nanowire array-based radial (core–shell) p-i-n junction betavoltaic cells for two- and three-dimensional radioisotope source geometries. Optimum short-circuit current density Jsc, open-circuit voltage Voc, fill factor FF, and energy conversion efficiency η are determined for various nanowire properties, including dopant concentration, nanowire length, core diameter, and shell thickness, for Si, GaAs, and GaP material systems. A maximum efficiency of 8.05% was obtained for GaP nanowires with diameter 200nm (p-core diameter, i-shell, and n-shell thicknesses of 24, 29.4, and 58.6 nm, respectively), length 10μm, acceptor and donor concentrations of 1019 and 5×1018cm−3, respectively, and a 3D source geometry.","PeriodicalId":502933,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140749631","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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