Abstract In recent years, atmospheric-pressure plasma jets (APPJs) have emerged as valuable tools in many application areas, including material modification, environmental remediation and biomedicine. Understanding the discharge characteristics of these plasma jets under various operating conditions is crucial for optimizing process outcomes. This paper presents a two-dimensional fluid model for numerical simulation to study the variation in electron density within an atmospheric-pressure helium plasma jet under different operating conditions. The investigated parameters include helium gas flow rate, voltage amplitude, needle-to-ring discharge gap, and relative permittivity of the dielectric tube. The results reveal that the peak electric field and electron density initially occur at the wall of the dielectric tube and subsequently shift towards the head of the propagating jet. Gas flow rate has minimal impact on the electron density throughout the plasma jet, whereas increasing the needle-to-ring discharge gap significantly decreases the average electron density within the jet. In addition, an increase in the voltage amplitude and the relative permittivity of the dielectric tube enhances the electric field within the discharge space, thereby increasing the electron density in the plasma jet. These findings underscore the importance of understanding the correlation between electron density and operating conditions to precisely control plasma jets and enhance material treatment effectiveness for specific applications.
{"title":"Influence of Operating Conditions on Electron Density in Atmospheric Pressure Helium Plasma Jets","authors":"wenwen xu, yonghang lu, xiaofeng Yue, xiaoping liu, Zhengwei Wu","doi":"10.1088/1361-6463/ad0479","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0479","url":null,"abstract":"Abstract In recent years, atmospheric-pressure plasma jets (APPJs) have emerged as valuable tools in many application areas, including material modification, environmental remediation and biomedicine. Understanding the discharge characteristics of these plasma jets under various operating conditions is crucial for optimizing process outcomes. This paper presents a two-dimensional fluid model for numerical simulation to study the variation in electron density within an atmospheric-pressure helium plasma jet under different operating conditions. The investigated parameters include helium gas flow rate, voltage amplitude, needle-to-ring discharge gap, and relative permittivity of the dielectric tube. The results reveal that the peak electric field and electron density initially occur at the wall of the dielectric tube and subsequently shift towards the head of the propagating jet. Gas flow rate has minimal impact on the electron density throughout the plasma jet, whereas increasing the needle-to-ring discharge gap significantly decreases the average electron density within the jet. In addition, an increase in the voltage amplitude and the relative permittivity of the dielectric tube enhances the electric field within the discharge space, thereby increasing the electron density in the plasma jet. These findings underscore the importance of understanding the correlation between electron density and operating conditions to precisely control plasma jets and enhance material treatment effectiveness for specific applications.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824761","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 : 2023-10-17DOI: 10.1088/1361-6463/ad015c
Natalith Palacios-Ortega, Maria Del Socorro Hernandez-Montes, Fernando Mendoza Santoyo, Mauricio Flores-Moreno, Manuel De la Torre Ibarra, Daniel Luis-Noriega, Pedro G. Méndez-Sashida
Abstract A keratoacanthoma (KA) skin tumor is usually caused by sun exposure and may be an alert sign prior to the development of a more aggressive tumor or skin cancer. Studying the shape of the KA cells and their 3D rendering visualization are important parameters to prevent its evolution to higher stages of tumor cells or skin cancer. KA cells shape can be obtained through digital holographic microscopy; for that purpose, a setup with two illumination wavelengths (532 and 638 nm) is implemented to render a synthetic wavelength of 3.2 μ m that avoids wrapping the optical phase of the processed holograms and increases measurement range. To recover the optical phase, two off-axis digital holograms are simultaneously recorded at each wavelength. From the processed hologram height variations, the shape and length of KA cells, as well as the stratum corneum epidermal layer, are obtained as phase images. The results achieved aid to discriminate healthy from malignant cells.
{"title":"Simultaneous dual-wavelength digital holographic microscopy as a tool for the analysis of keratoacanthoma skin samples","authors":"Natalith Palacios-Ortega, Maria Del Socorro Hernandez-Montes, Fernando Mendoza Santoyo, Mauricio Flores-Moreno, Manuel De la Torre Ibarra, Daniel Luis-Noriega, Pedro G. Méndez-Sashida","doi":"10.1088/1361-6463/ad015c","DOIUrl":"https://doi.org/10.1088/1361-6463/ad015c","url":null,"abstract":"Abstract A keratoacanthoma (KA) skin tumor is usually caused by sun exposure and may be an alert sign prior to the development of a more aggressive tumor or skin cancer. Studying the shape of the KA cells and their 3D rendering visualization are important parameters to prevent its evolution to higher stages of tumor cells or skin cancer. KA cells shape can be obtained through digital holographic microscopy; for that purpose, a setup with two illumination wavelengths (532 and 638 nm) is implemented to render a synthetic wavelength of 3.2 μ m that avoids wrapping the optical phase of the processed holograms and increases measurement range. To recover the optical phase, two off-axis digital holograms are simultaneously recorded at each wavelength. From the processed hologram height variations, the shape and length of KA cells, as well as the stratum corneum epidermal layer, are obtained as phase images. The results achieved aid to discriminate healthy from malignant cells.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135944153","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 : 2023-10-16DOI: 10.1088/1361-6463/ad039b
José Afonso, Luca Vialetto, Vasco Guerra, Pedro Viegas
Abstract A novel model is developed for atomic oxygen surface kinetics in silica-like walls, introducing a plasma-induced surface modification, which may impact intermediate pressure plasma reactors. The model is the first to reproduce experimental measurements in an oxygen glow discharge operating in the pressure range between 0.27 mbar (0.2 Torr) and 4 mbar (3 Torr), showing a decrease with pressure of the O recombination probability on Pyrex between 0.27 mbar and 1 mbar. The numerical simulations suggest that a modification is induced by the production and destruction of metastable chemisorption sites at the surface. As such, the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) recombination mechanisms take place involving not only physisorption (1) and stable chemisorption (2) sites, but also metastable chemisorption sites (3), produced by the impact of fast O2 ions and neutrals. The presence of metastable sites can be reversed by increasing the plasma pressure.
{"title":"Plasma-Induced Reversible Surface Modification and its Impact on Oxygen Heterogeneous Recombination","authors":"José Afonso, Luca Vialetto, Vasco Guerra, Pedro Viegas","doi":"10.1088/1361-6463/ad039b","DOIUrl":"https://doi.org/10.1088/1361-6463/ad039b","url":null,"abstract":"Abstract A novel model is developed for atomic oxygen surface kinetics in silica-like walls, introducing a plasma-induced surface modification, which may impact intermediate pressure plasma reactors. The model is the first to reproduce experimental measurements in an oxygen glow discharge operating in the pressure range between 0.27 mbar (0.2 Torr) and 4 mbar (3 Torr), showing a decrease with pressure of the O recombination probability on Pyrex between 0.27 mbar and 1 mbar. The numerical simulations suggest that a modification is induced by the production and destruction of metastable chemisorption sites at the surface. As such, the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) recombination mechanisms take place involving not only physisorption (1) and stable chemisorption (2) sites, but also metastable chemisorption sites (3), produced by the impact of fast O2 ions and neutrals. The presence of metastable sites can be reversed by increasing the plasma pressure.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136079743","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 : 2023-10-16DOI: 10.1088/1361-6463/ad00c8
Tong Zhou, Qing Yang, Tao Yuan, Hengxin He, Hongwen Liu
Abstract Medium voltage (MV) AC air arcs occur frequently in distribution networks. An electric arc can easily cause electrical fires, leading to serious accident consequences. Obtaining the electrical characteristics of arc faults through arc models is a crucial measure to detect and prevent arc faults. The arc electrical characteristics are affected by many factors such as the ambient air pressure, current magnitude, and arc length, and it is difficult to describe it in an analytical form. The widely used conventional black-box arc model reflects the influence of multiple factors on the electrical characteristics of arcs through fitting or empirical formulae. The model ignores the intrinsic physical and chemical processes, and the applicable range of the model is limited. Focusing on this problem, based on the physicochemical processes of the arc in the arcing and post-arcing stages, a relationship between the electrical and plasma characteristics of the MV AC air arc was established. Subsequently, the arc plasma characteristics were determined experimentally, and were applied to the calculation of the arc electric characteristics. Finally, the calculation results of the arc electrical characteristics were verified using the experimental results, providing a basis for related model improvements and applications.
{"title":"Plasma Characteristics of Medium Voltage AC Air Arc Discharge and Its Application on Arc Electrical Parameters Calculation","authors":"Tong Zhou, Qing Yang, Tao Yuan, Hengxin He, Hongwen Liu","doi":"10.1088/1361-6463/ad00c8","DOIUrl":"https://doi.org/10.1088/1361-6463/ad00c8","url":null,"abstract":"Abstract Medium voltage (MV) AC air arcs occur frequently in distribution networks. An electric arc can easily cause electrical fires, leading to serious accident consequences. Obtaining the electrical characteristics of arc faults through arc models is a crucial measure to detect and prevent arc faults. The arc electrical characteristics are affected by many factors such as the ambient air pressure, current magnitude, and arc length, and it is difficult to describe it in an analytical form. The widely used conventional black-box arc model reflects the influence of multiple factors on the electrical characteristics of arcs through fitting or empirical formulae. The model ignores the intrinsic physical and chemical processes, and the applicable range of the model is limited. Focusing on this problem, based on the physicochemical processes of the arc in the arcing and post-arcing stages, a relationship between the electrical and plasma characteristics of the MV AC air arc was established. Subsequently, the arc plasma characteristics were determined experimentally, and were applied to the calculation of the arc electric characteristics. Finally, the calculation results of the arc electrical characteristics were verified using the experimental results, providing a basis for related model improvements and applications.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136077734","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 : 2023-10-16DOI: 10.1088/1361-6463/ad039c
Arnob Ghosh, Agnes Maneesha Dominic Merwin Xavier, Syed M N Hasan, Sheikh Ifatur Rahman, Alex Blackston, Andrew A Allerman, Roberto C Myers, Siddharth Rajan, Shamsul Arafin
Abstract This paper presents the design, material growth and fabrication of AlGaN laser structures grown by plasma-assisted molecular beam epitaxy. Considering hole transport to be the major challenge, our ultraviolet-A diode laser structures have a compositionally graded transparent tunnel junction, resulting in superior hole injection and a low contact resistance. By optimizing active region thickness, a five-fold improvement in photoluminescence intensity is obtained compared to that of our own non-optimized test structures. The electrical and optical characteristics of processed devices demonstrate only spontaneous emission with a peak wavelength at 354 nm. The devices operate up to a continuous-wave current density of 11.1 kA/cm2 at room temperature, which is the highest reported for laser structures grown on AlGaN templates. Additionally, they exhibit a record-low voltage drop of 8.5 V to achieve this current density.
{"title":"Low Voltage Drop AlGaN UV-A Laser Structures with Transparent Tunnel Junctions and Optimized Quantum Wells","authors":"Arnob Ghosh, Agnes Maneesha Dominic Merwin Xavier, Syed M N Hasan, Sheikh Ifatur Rahman, Alex Blackston, Andrew A Allerman, Roberto C Myers, Siddharth Rajan, Shamsul Arafin","doi":"10.1088/1361-6463/ad039c","DOIUrl":"https://doi.org/10.1088/1361-6463/ad039c","url":null,"abstract":"Abstract This paper presents the design, material growth and fabrication of AlGaN laser structures grown by plasma-assisted molecular beam epitaxy. Considering hole transport to be the major challenge, our ultraviolet-A diode laser structures have a compositionally graded transparent tunnel junction, resulting in superior hole injection and a low contact resistance. By optimizing active region thickness, a five-fold improvement in photoluminescence intensity is obtained compared to that of our own non-optimized test structures. The electrical and optical characteristics of processed devices demonstrate only spontaneous emission with a peak wavelength at 354 nm. The devices operate up to a continuous-wave current density of 11.1 kA/cm2 at room temperature, which is the highest reported for laser structures grown on AlGaN templates. Additionally, they exhibit a record-low voltage drop of 8.5 V to achieve this current density.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136079744","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 : 2023-10-13DOI: 10.1088/1361-6463/ad0309
Songyi Zhang, Ailing Song, Shuai Wang, Xinhai Yu
Abstract In this work, a compact low-frequency sound absorption metastructure composed of multiple resonators with embedded wavy bending necks is proposed. By arranging this metastructure in parallel and optimizing the parameters, it exhibits excellent broadband sound absorption capability in low-frequency range and has a much more compact volume. Compared with the traditional resonators, an individual resonator of this metastructure can move down the absorption frequency about 120 Hz while maintaining the same thickness. Furthermore, different resonator units are combined into a sound absorption array by employing appropriate design techniques. We first built a small metastructure composed of four units to demonstrate the correctness and accuracy of our design method. Both theoretical models and finite element simulation models are built and experimental results show good agreement between them. To achieve the same absorption value and frequency range, the thickest resonator in the traditional resonator array must be 30% thicker than the one in the wavy bending neck resonator array, which means the overall size of the structure is 30% larger. Following this design method, perfect sound absorption within the frequency range of 248 Hz to 420 Hz is achieved with a compact volume of 53 mm in radius and 47 mm in height. The design strategy presents a new approach to achieve perfect broadband low-frequency sound absorption.
{"title":"A compact low-frequency sound absorption metastructure realized by resonators with wavy bending necks","authors":"Songyi Zhang, Ailing Song, Shuai Wang, Xinhai Yu","doi":"10.1088/1361-6463/ad0309","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0309","url":null,"abstract":"Abstract In this work, a compact low-frequency sound absorption metastructure composed of multiple resonators with embedded wavy bending necks is proposed. By arranging this metastructure in parallel and optimizing the parameters, it exhibits excellent broadband sound absorption capability in low-frequency range and has a much more compact volume. Compared with the traditional resonators, an individual resonator of this metastructure can move down the absorption frequency about 120 Hz while maintaining the same thickness. Furthermore, different resonator units are combined into a sound absorption array by employing appropriate design techniques. We first built a small metastructure composed of four units to demonstrate the correctness and accuracy of our design method. Both theoretical models and finite element simulation models are built and experimental results show good agreement between them. To achieve the same absorption value and frequency range, the thickest resonator in the traditional resonator array must be 30% thicker than the one in the wavy bending neck resonator array, which means the overall size of the structure is 30% larger. Following this design method, perfect sound absorption within the frequency range of 248 Hz to 420 Hz is achieved with a compact volume of 53 mm in radius and 47 mm in height. The design strategy presents a new approach to achieve perfect broadband low-frequency sound absorption.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"42 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853138","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}
Abstract The development of the flexible and robust metamaterial absorber is the great motivation for the new generation of microwave absorbers covering any conformal shape. The ceramic-polymer composites with variable dielectric constant within the microwave frequencies are proposed as a flexible middle dielectric spacer (MDS) layer to provide additional degree of design freedom for metamaterial absorber application. By varying the dielectric constant of MDS layer, the resonance band of metamaterial absorber can be tuned while retaining a low profile besides enhancing its EM performance for TM polarized wave. To formulate these composites, tetragonal structured Barium Titanate ( BaTiO3) powder is selected as an excellent candidate when mixed with elastomer Polydimethylsiloxane (PDMS) resulting in high mechanical strength substrates. Experimentally, samples with a range of dielectric permittivity from 2.81 to 5.67 were obtained for 0% to 20% volume fill fraction of BaTiO3 in PDMS. The obtained dielectric permittivities being consistent with Bruggeman effective medium theory. Utilizing an optimized composition (10% BaTiO3 ), resulting in εr = 4 substrate, an X-band flexible absorber is designed and fabricated to absorb more than 90% of incident EM waves within frequency band of 8.16-12.12 GHz.
{"title":"Flexible Dielectric Spacer with Tunable Dielectric Properties for Metamaterial Absorber Application","authors":"KAJAL CHAUDHARY, Sudha Malik, Gaganpreet Singh, Sudeb Bhattacharya, J Ramkumar, S Anantha Ramakrishna, Kumar Vaibhav Srivastava","doi":"10.1088/1361-6463/ad030e","DOIUrl":"https://doi.org/10.1088/1361-6463/ad030e","url":null,"abstract":"Abstract The development of the flexible and robust metamaterial absorber is the great motivation for the new generation of microwave absorbers covering any conformal shape. The ceramic-polymer composites with variable dielectric constant within the microwave frequencies are proposed as a flexible middle dielectric spacer (MDS) layer to provide additional degree of design freedom for metamaterial absorber application. By varying the dielectric constant of MDS layer, the resonance band of metamaterial absorber can be tuned while retaining a low profile besides enhancing its EM performance for TM polarized wave. To formulate these composites, tetragonal structured Barium Titanate ( BaTiO3) powder is selected as an excellent candidate when mixed with elastomer Polydimethylsiloxane (PDMS) resulting in high mechanical strength substrates. Experimentally, samples with a range of dielectric permittivity from 2.81 to 5.67 were obtained for 0% to 20% volume fill fraction of BaTiO3 in PDMS. The obtained dielectric permittivities being consistent with Bruggeman effective medium theory. Utilizing an optimized composition (10% BaTiO3 ), resulting in εr = 4 substrate, an X-band flexible absorber is designed and fabricated to absorb more than 90% of incident EM waves within frequency band of 8.16-12.12 GHz.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853434","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}
Abstract The p–n interface state and depletion layer region of solar cells were investigated using electrochemical impedance spectroscopy (EIS) measurements to elucidate the effect of varying thiourea (TU) concentrations in chemical bath deposition (CBD) on the photovoltaic properties of Cu 2 SnS 3 (CTS) solar cells. The photoconversion efficiency (PCE) increased as the TU concentration increased, peaking at 0.16 M and decreasing thereafter. Additionally, the constant phase element- p value, which is indicative of the p–n interface state in CTS solar cells, exhibited a similar trend to that of the PCE of CTS solar cells with increasing TU concentration. The decrease in the PCE was due to the electron recombination that occurred at the p–n interface of CTS solar cells with increasing TU concentrations. Therefore, to improve the PCE of the CTS solar cells, the TU concentration in CBD must be optimized because the p–n interface state is sensitive to changes in the growth conditions of CdS films. By studying the effects on the p–n interface state and depletion layer in CTS solar cells using EIS measurements, useful knowledge can be obtained to increase the PCE of all-sulfide-compound solar cells using n-type CdS films as well as CTS.
{"title":"Influence of thiourea concentration during deposition of a CdS buffer layer on the electric properties of Cu<sub>2</sub>SnS<sub>3</sub> solar cells","authors":"Ayaka Kanai, Soichiro Saito, Araki Hideaki, Kunihiko Tanaka","doi":"10.1088/1361-6463/ad00c7","DOIUrl":"https://doi.org/10.1088/1361-6463/ad00c7","url":null,"abstract":"Abstract The p–n interface state and depletion layer region of solar cells were investigated using electrochemical impedance spectroscopy (EIS) measurements to elucidate the effect of varying thiourea (TU) concentrations in chemical bath deposition (CBD) on the photovoltaic properties of Cu 2 SnS 3 (CTS) solar cells. The photoconversion efficiency (PCE) increased as the TU concentration increased, peaking at 0.16 M and decreasing thereafter. Additionally, the constant phase element- p value, which is indicative of the p–n interface state in CTS solar cells, exhibited a similar trend to that of the PCE of CTS solar cells with increasing TU concentration. The decrease in the PCE was due to the electron recombination that occurred at the p–n interface of CTS solar cells with increasing TU concentrations. Therefore, to improve the PCE of the CTS solar cells, the TU concentration in CBD must be optimized because the p–n interface state is sensitive to changes in the growth conditions of CdS films. By studying the effects on the p–n interface state and depletion layer in CTS solar cells using EIS measurements, useful knowledge can be obtained to increase the PCE of all-sulfide-compound solar cells using n-type CdS films as well as CTS.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135805679","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 : 2023-10-13DOI: 10.1088/1361-6463/ad030b
E. A. Rabiea, Aly Samy Abouhaswa, Hala Abomostafa
Abstract The fabrication of polymer nanocomposites with specialized traits is gaining popularity across the world due to novel added qualities. In this work we used a flash auto-combustion method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles and the casting method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite polymer films with doping of nanoparticles various from 1–5 wt. %. The effect of Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles addition on the structural, optical, and dielectric characteristics of nanocomposite polymer films was analyzed. The structural properties were studied using X-ray diffraction pattern (XRD), high resolution transmission electron microscope (HRTEM), Fourier transform infrared (FTIR), and field emission scanning electron microscope (FESEM). The effects of nanoparticles doping on ac conductivity, electric modulus, impedance, and dielectric constant were investigated. It shows that Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite films have higher values of permittivity and ac conductivity than PVA and exhibit lower values of dielectric loss, electric modulus, and impedance. The optical properties showed the indirect optical decreased from 4.8 to 4.4 eV. According to the experimental results, these nanocomposite polymer films show promise for laser CUT-OFF filters and energy storage devices.
{"title":"Structural, dielectric, and optical properties based on Spinel Ferrite (Mn0.5Fe1.5Mg0.5Ni0.5O4) nanoparticles filler reinforced PVA for optoelectronic, laser CUT-OFF filters and energy storage devices.","authors":"E. A. Rabiea, Aly Samy Abouhaswa, Hala Abomostafa","doi":"10.1088/1361-6463/ad030b","DOIUrl":"https://doi.org/10.1088/1361-6463/ad030b","url":null,"abstract":"Abstract The fabrication of polymer nanocomposites with specialized traits is gaining popularity across the world due to novel added qualities. In this work we used a flash auto-combustion method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles and the casting method to prepare Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite polymer films with doping of nanoparticles various from 1–5 wt. %. The effect of Mn0.5Fe1.5Mg0.5Ni0.5O4 nanoparticles addition on the structural, optical, and dielectric characteristics of nanocomposite polymer films was analyzed. The structural properties were studied using X-ray diffraction pattern (XRD), high resolution transmission electron microscope (HRTEM), Fourier transform infrared (FTIR), and field emission scanning electron microscope (FESEM). The effects of nanoparticles doping on ac conductivity, electric modulus, impedance, and dielectric constant were investigated. It shows that Mn0.5Fe1.5Mg0.5Ni0.5O4/PVA nanocomposite films have higher values of permittivity and ac conductivity than PVA and exhibit lower values of dielectric loss, electric modulus, and impedance. The optical properties showed the indirect optical decreased from 4.8 to 4.4 eV. According to the experimental results, these nanocomposite polymer films show promise for laser CUT-OFF filters and energy storage devices.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135854037","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 : 2023-10-13DOI: 10.1088/1361-6463/ad0308
Sutapa Chattopadhyay, Anjali Kshirsagar
Abstract Valleytronics has emerged as an interesting field of research in two-dimensional (2D) systems and uses the valley index or valley pseudospin to encode information. Spin-orbit coupling (SOC) and inversion symmetry breaking leads to spin-splitting of bands near the valleys. This property has promising device applications.
In order to find a new 2D material useful for valleytronics, we have designed hexagonal planar monolayers of cadmium chalcogenides (CdX, X = S, Se, Te) from the (111) surface of bulk CdX zinc blende structure. The structural, dynamic, mechanical and thermal stability of these structures is confirmed. Band structure study reveals valence band local maxima (valleys) at K and K′ symmetry points. Application of SOC initiates spin-splitting in the valleys that lifts the energy degeneracy and shows strong valley-spin coupling character. To initiate stronger SOC, we have substituted two Cd atoms in the almost planar monolayers by Sn atoms which increases the spin-splitting significantly. Zeeman-type spin-splitting is observed in the valley region and Rashba spin-splitting is observed at the Γ point for Sn-doped CdSe and CdTe monolayers. Berry curvature values are more in all the Sn-doped monolayers than the pristine monolayers. These newly designed monolayers are thus found to be suitable for valleytronics applications. Sn-doped monolayers show band inversion deep in the valence and conduction bands between Sn s and p and X p states but lack topological properties.

谷电子学是二维系统中一个有趣的研究领域，它使用谷指数或谷伪自旋来编码信息。自旋轨道耦合(SOC)和反转对称破缺导致了谷附近能带的自旋分裂。这一性质具有很好的器件应用前景。
为了找到一种新的用于谷电子的二维材料，我们从块状CdX锌闪锌矿结构的(111)表面设计了六方平面单层镉硫族化合物(CdX, X = S, Se, Te)。确定了这些结构的结构稳定性、动力稳定性、力学稳定性和热稳定性。带结构研究揭示了价带在K和K′对称点处的局部最大值(谷)。SOC的应用引发了谷中的自旋分裂，提高了能量简并性，表现出较强的谷-自旋耦合特性。为了引发更强的SOC，我们用Sn原子取代了几乎是平面的单层中的两个Cd原子，这大大增加了自旋分裂。掺杂锡的CdSe和CdTe单层在谷区观察到zeeman型自旋分裂，在Γ点观察到Rashba自旋分裂。所有掺杂锡的单分子膜的Berry曲率值都大于未掺杂锡的单分子膜。因此，这些新设计的单分子层被发现适用于谷电子应用。掺杂锡的单层膜在锡s、p态和p态之间的价带和导带深处显示出能带反转，但缺乏拓扑性质。
{"title":"Design of Sn-doped cadmium chalcogenide based monolayers for valleytronics properties","authors":"Sutapa Chattopadhyay, Anjali Kshirsagar","doi":"10.1088/1361-6463/ad0308","DOIUrl":"https://doi.org/10.1088/1361-6463/ad0308","url":null,"abstract":"Abstract Valleytronics has emerged as an interesting field of research in two-dimensional (2D) systems and uses the valley index or valley pseudospin to encode information. Spin-orbit coupling (SOC) and inversion symmetry breaking leads to spin-splitting of bands near the valleys. This property has promising device applications.&#xD;In order to find a new 2D material useful for valleytronics, we have designed hexagonal planar monolayers of cadmium chalcogenides (CdX, X = S, Se, Te) from the (111) surface of bulk CdX zinc blende structure. The structural, dynamic, mechanical and thermal stability of these structures is confirmed. Band structure study reveals valence band local maxima (valleys) at K and K′ symmetry points. Application of SOC initiates spin-splitting in the valleys that lifts the energy degeneracy and shows strong valley-spin coupling character. To initiate stronger SOC, we have substituted two Cd atoms in the almost planar monolayers by Sn atoms which increases the spin-splitting significantly. Zeeman-type spin-splitting is observed in the valley region and Rashba spin-splitting is observed at the Γ point for Sn-doped CdSe and CdTe monolayers. Berry curvature values are more in all the Sn-doped monolayers than the pristine monolayers. These newly designed monolayers are thus found to be suitable for valleytronics applications. Sn-doped monolayers show band inversion deep in the valence and conduction bands between Sn s and p and X p states but lack topological properties.&#xD;&#xD;","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135853618","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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