Pub Date : 2025-06-02DOI: 10.1016/j.physo.2025.100275
M. Amzaoued , S. Zriouel , M. Mabrouki
This paper presents a first-principles investigation of the electronic structure and magnetism of dilute magnetic semiconductors (DMSs), with a particular focus on transition-metal-doped systems relevant to spintronic applications. Using density functional theory within the local-density approximation, we explore how magnetic impurities influence the electronic states and magnetic interactions in where transition metal atoms namely , , , and and is the fractional concentration of . The total and partial density of states, as well as the calculated Curie temperatures , are carefully analyzed and discussed. Our results demonstrate that the electronic configuration of the dopant atoms plays a crucial role in stabilizing ferromagnetic ordering, revealing distinct trends across different transition-metal elements . The emergence of half-metallic ferromagnetism in is interpreted in terms of the electronic states. Using a mean-field theoretical approach, we estimate the Curie temperatures for various DMS systems, obtaining values that align well with available experimental data. These findings provide valuable insights into the underlying mechanisms of magnetism in DMSs and support the development of a comprehensive model for understanding chemical trends, ultimately guiding the design of high materials for future spintronic technologies.
{"title":"DFT computational modeling studies of electronic and magnetic features of transition metal doped ZnTe","authors":"M. Amzaoued , S. Zriouel , M. Mabrouki","doi":"10.1016/j.physo.2025.100275","DOIUrl":"10.1016/j.physo.2025.100275","url":null,"abstract":"<div><div>This paper presents a first-principles investigation of the electronic structure and magnetism of dilute magnetic semiconductors (DMSs), with a particular focus on transition-metal-doped <span><math><mrow><mi>Z</mi><mi>n</mi><mi>T</mi><mi>e</mi></mrow></math></span> systems relevant to spintronic applications. Using density functional theory within the local-density approximation, we explore how magnetic impurities influence the electronic states and magnetic interactions in <span><math><mrow><mi>Z</mi><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><mi>T</mi><msub><mrow><mi>M</mi></mrow><mrow><mi>x</mi></mrow></msub><mi>T</mi><mi>e</mi></mrow></math></span> where <span><math><mrow><mi>T</mi><mi>M</mi><mo>=</mo><mn>3</mn><mi>d</mi></mrow></math></span> transition metal atoms namely <span><math><mi>V</mi></math></span>, <span><math><mrow><mi>C</mi><mi>r</mi></mrow></math></span>, <span><math><mrow><mi>M</mi><mi>n</mi></mrow></math></span>, and <span><math><mrow><mi>C</mi><mi>o</mi></mrow></math></span> and <span><math><mi>x</mi></math></span> is the fractional concentration of <span><math><mrow><mi>T</mi><mi>M</mi></mrow></math></span>. The total and partial density of states, as well as the calculated Curie temperatures <span><math><mrow><mo>(</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>C</mi></mrow></msub><mo>)</mo></mrow></math></span>, are carefully analyzed and discussed. Our results demonstrate that the electronic configuration of the dopant atoms plays a crucial role in stabilizing ferromagnetic ordering, revealing distinct trends across different transition-metal elements <span><math><mrow><mo>(</mo><mi>T</mi><mi>M</mi><mo>)</mo></mrow></math></span>. The emergence of half-metallic ferromagnetism in <span><math><mrow><mi>Z</mi><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><mi>T</mi><msub><mrow><mi>M</mi></mrow><mrow><mi>x</mi></mrow></msub><mi>T</mi><mi>e</mi></mrow></math></span> is interpreted in terms of the <span><math><mrow><mi>T</mi><mi>M</mi><mo>−</mo><mn>3</mn><mi>d</mi></mrow></math></span> electronic states. Using a mean-field theoretical approach, we estimate the Curie temperatures for various DMS systems, obtaining values that align well with available experimental data. These findings provide valuable insights into the underlying mechanisms of magnetism in DMSs and support the development of a comprehensive model for understanding chemical trends, ultimately guiding the design of high<span><math><mrow><mo>−</mo><msub><mrow><mi>T</mi></mrow><mrow><mi>C</mi></mrow></msub></mrow></math></span> materials for future spintronic technologies.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100275"},"PeriodicalIF":0.0,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144330300","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}
Pub Date : 2025-05-28DOI: 10.1016/j.physo.2025.100283
Tan Nguyen Tien , Duc Tran Duy , Vinh Nguyen Duy , Dien Vu Minh , Hoa Binh Pham , Quang Khong Vu
Thermoelectric generators (TEGs), known as devices, convert waste heat to potential electricity. TEGs feature simple assembly, quiet work, non-exhaust, and stability based on thermodynamics together with Seebeck, Peltier, and Thomson effects. However, the performance of TEG is not high because the thermoelectric conversion inside TEG faces low efficiency. Typically, the cooling exchanger mounted in TEG partly affects the thermoelectric conversion. This paper offers three alternatives to the cooling exchanger based on a commercial model with different channel profiles. All are simulated and evaluated as thermodynamic and mass factors for TEG performance, such as temperature, pressure, and occupied solid volume. Then, two optimal alternatives based on three prior alternatives are analyzed, as well as properties and non-symmetric effects on TEG performance. Therefore, the results show that the different temperatures between the central fluid of the cooling exchanger and the top plate plane of TEG in optimized alternatives are larger than in the commercial model (i.e., 185 K and 183 K for optimal alternatives and 167 K for the commercial model with 5 L/min of mass flow rate inlet).
{"title":"A numerical model and comparative investigation of a thermoelectric generator with novel profile designs","authors":"Tan Nguyen Tien , Duc Tran Duy , Vinh Nguyen Duy , Dien Vu Minh , Hoa Binh Pham , Quang Khong Vu","doi":"10.1016/j.physo.2025.100283","DOIUrl":"10.1016/j.physo.2025.100283","url":null,"abstract":"<div><div>Thermoelectric generators (TEGs), known as devices, convert waste heat to potential electricity. TEGs feature simple assembly, quiet work, non-exhaust, and stability based on thermodynamics together with Seebeck, Peltier, and Thomson effects. However, the performance of TEG is not high because the thermoelectric conversion inside TEG faces low efficiency. Typically, the cooling exchanger mounted in TEG partly affects the thermoelectric conversion. This paper offers three alternatives to the cooling exchanger based on a commercial model with different channel profiles. All are simulated and evaluated as thermodynamic and mass factors for TEG performance, such as temperature, pressure, and occupied solid volume. Then, two optimal alternatives based on three prior alternatives are analyzed, as well as properties and non-symmetric effects on TEG performance. Therefore, the results show that the different temperatures between the central fluid of the cooling exchanger and the top plate plane of TEG in optimized alternatives are larger than in the commercial model (i.e., 185 K and 183 K for optimal alternatives and 167 K for the commercial model with 5 L/min of mass flow rate inlet).</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100283"},"PeriodicalIF":0.0,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144178590","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}
Pub Date : 2025-05-23DOI: 10.1016/j.physo.2025.100274
H.S. Tang, Priata Saha
Head loss plays a central role in fluid flows. The head loss in fully developed, steady flows is relatively clear, and its calculation has matured and been applied widely in practical problems with success. However, there is a lack of understanding and effective methods to estimate head loss in non-fully developed, unsteady flows. This paper revisits a Reynolds experiment, which, unlike the original experiment by Reynolds in 1883, adopts unsteady flows (with non-constant water heads) exhibiting negative inertia heads. It discusses their head loss in a tube section where the flows have not fully developed. It shows that the head loss is higher in unsteady flows than in steady flows, with the difference being about two orders of magnitude greater than the inertia head. Also, it illustrates that the Darcy-Weisbach equation cannot replicate the measurement data for the head loss in both steady and unsteady, non-fully developed flows. Moreover, the paper presents an expression for head loss in such unsteady flows in terms of steady-flow head loss and inertia head.
{"title":"Revisiting a Reynolds experiment: head loss in non-fully developed, unsteady flow","authors":"H.S. Tang, Priata Saha","doi":"10.1016/j.physo.2025.100274","DOIUrl":"10.1016/j.physo.2025.100274","url":null,"abstract":"<div><div>Head loss plays a central role in fluid flows. The head loss in fully developed, steady flows is relatively clear, and its calculation has matured and been applied widely in practical problems with success. However, there is a lack of understanding and effective methods to estimate head loss in non-fully developed, unsteady flows. This paper revisits a Reynolds experiment, which, unlike the original experiment by Reynolds in 1883, adopts unsteady flows (with non-constant water heads) exhibiting negative inertia heads. It discusses their head loss in a tube section where the flows have not fully developed. It shows that the head loss is higher in unsteady flows than in steady flows, with the difference being about two orders of magnitude greater than the inertia head. Also, it illustrates that the Darcy-Weisbach equation cannot replicate the measurement data for the head loss in both steady and unsteady, non-fully developed flows. Moreover, the paper presents an expression for head loss in such unsteady flows in terms of steady-flow head loss and inertia head.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100274"},"PeriodicalIF":0.0,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144242829","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 explores the intricate relationship between hydrogen and the microstructural elements of austenitic stainless steels and nickel-based superalloys, with particular focus on their propensity for hydrogen embrittlement (HE). Utilizing sophisticated simulation tools within the ANSYS framework, we have developed an in-depth 3D model that intricately portrays the subtle hydrogen diffusion dynamics as they interact with microstructural features, including grain boundaries, dislocations, precipitates, and the lattice framework. This model illuminates the pivotal roles these microstructural interfaces play in the transportation and trapping of hydrogen and their contribution to the vulnerability of these alloys to HE. Our findings reveal that dislocations serve as a critical factor in dictating hydrogen diffusion behavior, which offer alternative pathways significantly influencing hydrogen distribution throughout the microstructure. The behavior of these dislocations is found to be highly temperature-sensitive, exhibiting distinct properties under varying thermal conditions and over extended durations. The simulation results are consistent with established models of hydrogen behavior in metallic systems and confirm that both microstructural nuances and temperature have a significant influence on hydrogen diffusion, which is in line with theoretical expectations. The insights gleaned from this research will assist in the engineering of materials that are more resilient to the deleterious effects of hydrogen penetration, thereby enhancing the safety and dependability of components operating in hydrogen-intensive environments.
{"title":"3D modelling of hydrogen embrittlement in austenitic stainless steel and nickel-based superalloy: Physical metallurgy aspects on hydrogen entrapment","authors":"Behzad Sadeghi , Pasquale Cavaliere , Alicja Stanislawska","doi":"10.1016/j.physo.2025.100253","DOIUrl":"10.1016/j.physo.2025.100253","url":null,"abstract":"<div><div>This study explores the intricate relationship between hydrogen and the microstructural elements of austenitic stainless steels and nickel-based superalloys, with particular focus on their propensity for hydrogen embrittlement (HE). Utilizing sophisticated simulation tools within the ANSYS framework, we have developed an in-depth 3D model that intricately portrays the subtle hydrogen diffusion dynamics as they interact with microstructural features, including grain boundaries, dislocations, precipitates, and the lattice framework. This model illuminates the pivotal roles these microstructural interfaces play in the transportation and trapping of hydrogen and their contribution to the vulnerability of these alloys to HE. Our findings reveal that dislocations serve as a critical factor in dictating hydrogen diffusion behavior, which offer alternative pathways significantly influencing hydrogen distribution throughout the microstructure. The behavior of these dislocations is found to be highly temperature-sensitive, exhibiting distinct properties under varying thermal conditions and over extended durations. The simulation results are consistent with established models of hydrogen behavior in metallic systems and confirm that both microstructural nuances and temperature have a significant influence on hydrogen diffusion, which is in line with theoretical expectations. The insights gleaned from this research will assist in the engineering of materials that are more resilient to the deleterious effects of hydrogen penetration, thereby enhancing the safety and dependability of components operating in hydrogen-intensive environments.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100253"},"PeriodicalIF":0.0,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144212932","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}
Pub Date : 2025-05-16DOI: 10.1016/j.physo.2025.100279
Ján Ziman, Jozef Onufer, Peter Duranka, Mária Kladivová, Peter Vrábel
The paper presents the study of the motion of an individual domain wall in a cylindrical amorphous wire with negative magnetostriction and helical anisotropy induced by the simultaneous application of torsional and tensile mechanical stresses. The non-zero axial component of the magnetization made it possible to monitor the motion of the domain wall by means of suitably wound pick-up coils. Experimental results showed that the wall mobility increases significantly with the application of torsional stress. For a model of a planar domain wall, the calculated eddy currents damping of the wall motion is too strong to explain this increase. Presence of a non-zero axial component of the magnetization can cause the transformation of a planar wall to a deformed wall, axial length of which increases with the applied torsion. It can be expected that the damping of the propagating deformed wall is lower and thus its mobility increases.
{"title":"Effects of applied mechanical stress on the properties of the boundary between circular domains in a cylindrical magnetic wire","authors":"Ján Ziman, Jozef Onufer, Peter Duranka, Mária Kladivová, Peter Vrábel","doi":"10.1016/j.physo.2025.100279","DOIUrl":"10.1016/j.physo.2025.100279","url":null,"abstract":"<div><div>The paper presents the study of the motion of an individual domain wall in a cylindrical amorphous wire with negative magnetostriction and helical anisotropy induced by the simultaneous application of torsional and tensile mechanical stresses. The non-zero axial component of the magnetization made it possible to monitor the motion of the domain wall by means of suitably wound pick-up coils. Experimental results showed that the wall mobility increases significantly with the application of torsional stress. For a model of a planar domain wall, the calculated eddy currents damping of the wall motion is too strong to explain this increase. Presence of a non-zero axial component of the magnetization can cause the transformation of a planar wall to a deformed wall, axial length of which increases with the applied torsion. It can be expected that the damping of the propagating deformed wall is lower and thus its mobility increases.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100279"},"PeriodicalIF":0.0,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099430","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}
Pub Date : 2025-05-16DOI: 10.1016/j.physo.2025.100282
Mahmoud A. Hamad , Tahani R. Aldhafeeri , Hatem R. Alamri , Mohamed E. Harb
The magnetocaloric effectin Mn55Al45C2 alloys synthesized via induction heating is investigated, ranging from 450 to 650 K. The experimental and modelled thermo-magnetization for Mn55Al45C2 alloys at 0.1 T agree well, highlighting that PM is a reliable method for simulating thermo-magnetization for Mn55Al45C2 alloys. The maximum values magnetic entropy changes for Mn55Al45C2 alloys are 55 mJ/kg.K and 47 mJ/kg.K, respectively, with full-width at half-maximum of 70 and 65 K. The relative cooling power and refrigerant capacity values reaches 3.88 J/kg and 2.8 J/kg, respectively. It is proposed that Mn55Al45C2 be used as attracting magnets in magnetic refrigeration to address the issue of rising battery and motor temperatures, hence improving the electric and hybrid vehicles' performance.
{"title":"Thermo-magnetic characterization of Mn55Al45C2 for high temperature devices","authors":"Mahmoud A. Hamad , Tahani R. Aldhafeeri , Hatem R. Alamri , Mohamed E. Harb","doi":"10.1016/j.physo.2025.100282","DOIUrl":"10.1016/j.physo.2025.100282","url":null,"abstract":"<div><div>The magnetocaloric effectin Mn<sub>55</sub>Al<sub>45</sub>C<sub>2</sub> alloys synthesized via induction heating is investigated, ranging from 450 to 650 K. The experimental and modelled thermo-magnetization for Mn<sub>55</sub>Al<sub>45</sub>C<sub>2</sub> alloys at 0.1 T agree well, highlighting that PM is a reliable method for simulating thermo-magnetization for Mn<sub>55</sub>Al<sub>45</sub>C<sub>2</sub> alloys. The maximum values magnetic entropy changes for Mn<sub>55</sub>Al<sub>45</sub>C<sub>2</sub> alloys are 55 mJ/kg.K and 47 mJ/kg.K, respectively, with full-width at half-maximum of 70 and 65 K. The relative cooling power and refrigerant capacity values reaches 3.88 J/kg and 2.8 J/kg, respectively. It is proposed that Mn<sub>55</sub>Al<sub>45</sub>C<sub>2</sub> be used as attracting magnets in magnetic refrigeration to address the issue of rising battery and motor temperatures, hence improving the electric and hybrid vehicles' performance.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100282"},"PeriodicalIF":0.0,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144099408","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}
Pub Date : 2025-05-14DOI: 10.1016/j.physo.2025.100280
K. Gherbi , M.T. Kadri , H. Belkhir , K. Zanat
This study explores the structural, electronic, and optical characteristics of X-terminated germanene nanoribbons (GeNRs) featuring armchair (7-AGeNR) and zigzag (5-ZGeNR) arrangements through first-principles calculations. The findings illustrate how halogen edge functionalization (H, F, Cl, Br, I) significantly modifies the geometric, electronic, and optical traits of GeNRs. Specifically, the Ge-Ge bond length (2.44 Å) and the buckling height (0.69 Å) of the 7-AGeNRs are affected by the size of the X-terminated atoms, with larger halogens leading to increased bond lengths and changes in electronic properties. The analysis of the electronic band structure indicates that halogen passivation introduces a bandgap in the nanoribbons, with 7-AGeNRs-F displaying the largest bandgap of 0.60 eV, as opposed to 0.37 eV for 7-AGeNRs-I. We provide new insights into the tunable anisotropy of the dielectric constant and distinct optical transitions induced by halogen edge functionalization. The optical properties exhibit notable anisotropy, with 7-AGeNR-H showing a dielectric constant of and , while I-termination leads to reduced values of 7.762 and 5.031, respectively. Furthermore, a redshift in absorption is observed for 7-AGeNRs with heavier halogens, while 5-ZGeNRs demonstrate a blueshift. Reflectivity and plasma frequency analyses point to an optical anisotropy, where H-terminated 7-AGeNR shows a high reflectivity of , which diminishes with heavier halogens. These adjustable properties indicate the potential application of GeNRs in optoelectronic devices, including infrared (IR) detectors, ultraviolet (UV) sensors, and photovoltaic systems.
{"title":"Anisotropic and tunable properties of hydrogen/halogen-terminated germanene nanoribbons for advanced optoelectronics","authors":"K. Gherbi , M.T. Kadri , H. Belkhir , K. Zanat","doi":"10.1016/j.physo.2025.100280","DOIUrl":"10.1016/j.physo.2025.100280","url":null,"abstract":"<div><div>This study explores the structural, electronic, and optical characteristics of X-terminated germanene nanoribbons (GeNRs) featuring armchair (7-AGeNR) and zigzag (5-ZGeNR) arrangements through first-principles calculations. The findings illustrate how halogen edge functionalization (H, F, Cl, Br, I) significantly modifies the geometric, electronic, and optical traits of GeNRs. Specifically, the Ge-Ge bond length (2.44 Å) and the buckling height (0.69 Å) of the 7-AGeNRs are affected by the size of the X-terminated atoms, with larger halogens leading to increased bond lengths and changes in electronic properties. The analysis of the electronic band structure indicates that halogen passivation introduces a bandgap in the nanoribbons, with 7-AGeNRs-F displaying the largest bandgap of 0.60 eV, as opposed to 0.37 eV for 7-AGeNRs-I. We provide new insights into the tunable anisotropy of the dielectric constant and distinct optical transitions induced by halogen edge functionalization. The optical properties exhibit notable anisotropy, with 7-AGeNR-H showing a dielectric constant of <span><math><mrow><msubsup><mi>ε</mi><mn>1</mn><mrow><mi>x</mi><mi>x</mi></mrow></msubsup><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><mn>12.984</mn></mrow></math></span> and <span><math><mrow><msubsup><mi>ε</mi><mn>1</mn><mrow><mi>y</mi><mi>y</mi></mrow></msubsup><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><mn>4.127</mn></mrow></math></span>, while I-termination leads to reduced values of 7.762 and 5.031, respectively. Furthermore, a redshift in absorption is observed for 7-AGeNRs with heavier halogens, while 5-ZGeNRs demonstrate a blueshift. Reflectivity and plasma frequency analyses point to an optical anisotropy, where H-terminated 7-AGeNR shows a high reflectivity of <span><math><mrow><msup><mi>R</mi><mrow><mi>x</mi><mi>x</mi></mrow></msup><mrow><mo>(</mo><mn>0</mn><mo>)</mo></mrow><mo>=</mo><mn>0.320</mn></mrow></math></span>, which diminishes with heavier halogens. These adjustable properties indicate the potential application of GeNRs in optoelectronic devices, including infrared (IR) detectors, ultraviolet (UV) sensors, and photovoltaic systems.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100280"},"PeriodicalIF":0.0,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072324","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}
Pub Date : 2025-05-14DOI: 10.1016/j.physo.2025.100281
Yuqi Han , Jieyuan Tang , Jianshang Liao , Li Tan
Aluminum is a widely used and cost-effective material for marine equipment because of its strong adhesion and simple coating processes. This study utilizes finite element numerical analysis to examine the sensing characteristics and sensitivity of aluminum-side-polished fiber (SPF) surface plasmon resonance (SPR) sensors with varying aluminum film thicknesses. Additionally, it investigates the response characteristics of these sensors to different surface roughness morphologies. The simulation results reveal that for SPF-based SPR sensors with a remaining thickness of 1 μm under a wavelength of 1550 nm, the coupling depth of the SPR resonance peak initially deepens and then shallow increases as the aluminum film thickness increases from 20 nm to 50 nm, achieving maximum coupling depth and sensitivity of 857 nm/RIU at 30 nm thickness. Models of aluminum-SPF-based SPR sensors were developed for ideally smooth, periodically rough, and randomly rough surface morphologies. The simulations reveal that as the surface morphology of the fiber transitions from smooth to periodically rough to randomly rough, the SPR resonance peak shifts from 961 nm to 954 nm and then to 885 nm, with the blue shift range increasing as the random roughness of the fiber surface intensifies. These simulations confirm the efficacy of aluminum-SPF-based SPR sensors in detecting variations in surface roughness morphology, establishing a theoretical foundation for the further application of these sensors in developing new sensing platforms for detecting corrosion in marine equipment materials in marine environments.
{"title":"Sensing response of aluminum-side-polished fiber-based surface plasmon resonance sensors to surface roughness","authors":"Yuqi Han , Jieyuan Tang , Jianshang Liao , Li Tan","doi":"10.1016/j.physo.2025.100281","DOIUrl":"10.1016/j.physo.2025.100281","url":null,"abstract":"<div><div>Aluminum is a widely used and cost-effective material for marine equipment because of its strong adhesion and simple coating processes. This study utilizes finite element numerical analysis to examine the sensing characteristics and sensitivity of aluminum-side-polished fiber (SPF) surface plasmon resonance (SPR) sensors with varying aluminum film thicknesses. Additionally, it investigates the response characteristics of these sensors to different surface roughness morphologies. The simulation results reveal that for SPF-based SPR sensors with a remaining thickness of 1 μm under a wavelength of 1550 nm, the coupling depth of the SPR resonance peak initially deepens and then shallow increases as the aluminum film thickness increases from 20 nm to 50 nm, achieving maximum coupling depth and sensitivity of 857 nm/RIU at 30 nm thickness. Models of aluminum-SPF-based SPR sensors were developed for ideally smooth, periodically rough, and randomly rough surface morphologies. The simulations reveal that as the surface morphology of the fiber transitions from smooth to periodically rough to randomly rough, the SPR resonance peak shifts from 961 nm to 954 nm and then to 885 nm, with the blue shift range increasing as the random roughness of the fiber surface intensifies. These simulations confirm the efficacy of aluminum-SPF-based SPR sensors in detecting variations in surface roughness morphology, establishing a theoretical foundation for the further application of these sensors in developing new sensing platforms for detecting corrosion in marine equipment materials in marine environments.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100281"},"PeriodicalIF":0.0,"publicationDate":"2025-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069106","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}
Pub Date : 2025-05-13DOI: 10.1016/j.physo.2025.100278
Mohammad Nazmul Hasan , Md N.J. Rifat , Jahid Kabir Rony , Md Saiduzzaman , Minhajul Islam
Cubic-structured perovskite compounds used in solar cells, made without lead (Pb) or other harmful materials, are becoming increasingly important as photovoltaic systems gain commercial viability. This investigation models the structural, mechanical, electronic, bonding, and optical behavior of Pb-free inorganic metal-halide cubic perovskite compounds NaGeX3 (X = Cl, Br, I) for advanced microelectronics using first-principles density functional theory calculations. The lattice constants for NaGeCl3 (5.226 Å), NaGeBr3 (5.498 Å), and NaGeI3 (5.893 Å) show excellent agreement with previously published data. The studied compounds are semiconductors with optimized band gaps and are found to be structurally, thermodynamically, mechanically, and vibrationally stable. The sX functional was utilized to enhance the accuracy of the energy band gap calculations, resulting in significantly improved band gap values for NaGeCl3 (1.76 eV), NaGeBr3 (1.65 eV), and NaGeI3 (1.22 eV). The calculated ductility, Vickers hardness, and machinability index values exhibit the following trend: NaGeCl3 > NaGeBr3 > NaGeI3. The compounds are suited for use in photovoltaic devices such as solar cells and other optoelectronic sensor systems because they have excellent optical conductivity, a high absorption coefficient, and low reflectance. It can be considered whether germanium (Ge) could serve as a suitable substitute for Pb, given its optical properties, as Ge-containing compounds demonstrate enhanced optical absorption and optical conductivity. In accordance with a comparative assessment of the compounds' electronic, optical, and mechanical behavior, NaGeI3-based perovskite is the optimal comparative to Pb-free inorganic metal-halide perovskite semiconductor for the usage of solar cells. This investigation offers valuable insights for developing lead-free inorganic perovskites suitable for optoelectronic applications and serves as a theoretical foundation to support future experimental validation of the selected compounds for practical use.
{"title":"First-principles investigation of NaGeX3 (X = Cl, Br, I) perovskites for eco-friendly photovoltaic and optoelectronic applications","authors":"Mohammad Nazmul Hasan , Md N.J. Rifat , Jahid Kabir Rony , Md Saiduzzaman , Minhajul Islam","doi":"10.1016/j.physo.2025.100278","DOIUrl":"10.1016/j.physo.2025.100278","url":null,"abstract":"<div><div>Cubic-structured perovskite compounds used in solar cells, made without lead (Pb) or other harmful materials, are becoming increasingly important as photovoltaic systems gain commercial viability. This investigation models the structural, mechanical, electronic, bonding, and optical behavior of Pb-free inorganic metal-halide cubic perovskite compounds NaGeX<sub>3</sub> (X = Cl, Br, I) for advanced microelectronics using first-principles density functional theory calculations. The lattice constants for NaGeCl<sub>3</sub> (5.226 Å), NaGeBr<sub>3</sub> (5.498 Å), and NaGeI<sub>3</sub> (5.893 Å) show excellent agreement with previously published data. The studied compounds are semiconductors with optimized band gaps and are found to be structurally, thermodynamically, mechanically, and vibrationally stable. The sX functional was utilized to enhance the accuracy of the energy band gap calculations, resulting in significantly improved band gap values for NaGeCl<sub>3</sub> (1.76 eV), NaGeBr<sub>3</sub> (1.65 eV), and NaGeI<sub>3</sub> (1.22 eV). The calculated ductility, Vickers hardness, and machinability index values exhibit the following trend: NaGeCl<sub>3</sub> > NaGeBr<sub>3</sub> > NaGeI<sub>3</sub>. The compounds are suited for use in photovoltaic devices such as solar cells and other optoelectronic sensor systems because they have excellent optical conductivity, a high absorption coefficient, and low reflectance. It can be considered whether germanium (Ge) could serve as a suitable substitute for Pb, given its optical properties, as Ge-containing compounds demonstrate enhanced optical absorption and optical conductivity. In accordance with a comparative assessment of the compounds' electronic, optical, and mechanical behavior, NaGeI<sub>3</sub>-based perovskite is the optimal comparative to Pb-free inorganic metal-halide perovskite semiconductor for the usage of solar cells. This investigation offers valuable insights for developing lead-free inorganic perovskites suitable for optoelectronic applications and serves as a theoretical foundation to support future experimental validation of the selected compounds for practical use.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100278"},"PeriodicalIF":0.0,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144069108","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}
Pub Date : 2025-05-06DOI: 10.1016/j.physo.2025.100271
Maxim J. Goldberg , Seonja Kim
Given an irreducible finite Markov chain, we propose the mean first passage time (MFPT) as a diffusion distance. We motivate this definition by considering a compact Riemannian manifold, and the submanifold resulting from removing the closure of a small ball. The steady-state solution to an associated inhomogeneous heat flow problem on the submanifold is non-negative and can be viewed as having large values at locations which are “far” away from the removed ball. The same function is also shown, at any point, to “count”, via probability, the paths starting at that point which miss the ball. As a third viewpoint, the same function gives the expected value of the first hitting time of the removed ball. The latter interpretation leads to our proposing the MFPT as a diffusion distance for a given finite set of states (samples) and an associated transition matrix. Even if the transition matrix does not arise from heat flow, and may in fact be non-symmetric and non-bistochastic, we note that the MFPT satisfies the triangle inequality. Moreover, various efficient ways to compute the MFPT, and approximations to the MFPT, have been proposed in the literature.
Additionally, we establish a novel connection between certain mean first passage times and the sum of squares of Coifman-Lafon diffusion distances across all scales.
{"title":"The mean first passage time as a natural diffusion distance","authors":"Maxim J. Goldberg , Seonja Kim","doi":"10.1016/j.physo.2025.100271","DOIUrl":"10.1016/j.physo.2025.100271","url":null,"abstract":"<div><div>Given an irreducible finite Markov chain, we propose the mean first passage time (MFPT) as a diffusion distance. We motivate this definition by considering a compact Riemannian manifold, and the submanifold resulting from removing the closure of a small ball. The steady-state solution to an associated inhomogeneous heat flow problem on the submanifold is non-negative and can be viewed as having large values at locations which are “far” away from the removed ball. The same function is also shown, at any point, to “count”, via probability, the paths starting at that point which miss the ball. As a third viewpoint, the same function gives the expected value of the first hitting time of the removed ball. The latter interpretation leads to our proposing the MFPT as a diffusion distance for a given finite set of states (samples) and an associated transition matrix. Even if the transition matrix does not arise from heat flow, and may in fact be non-symmetric and non-bistochastic, we note that the MFPT satisfies the triangle inequality. Moreover, various efficient ways to compute the MFPT, and approximations to the MFPT, have been proposed in the literature.</div><div>Additionally, we establish a novel connection between certain mean first passage times and the sum of squares of Coifman-Lafon diffusion distances across all scales.</div></div>","PeriodicalId":36067,"journal":{"name":"Physics Open","volume":"24 ","pages":"Article 100271"},"PeriodicalIF":0.0,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143928907","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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