Pub Date : 2020-10-01DOI: 10.1051/epjap/2020200113
J. Schoenmaker, P. Martins, Guilherme Silva, Júlio, Carlos J C Teixeira
Organic Rankine Cycle (ORC) systems are increasingl y gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organ ic Rankine Cycle (BORC) (Schoenmaker et al., 2011). In this work we present two main contribut ions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dic hloromethane at temperatures up to 100°C were estimated to be 17.2%. Second, we show a proof of c oncept BORC system using a 3 m tall, 0,062 m diameter polycarbonate tube as a column-fluid reser voir. We used water as a column fluid. The thermal stability and uniformity throughout the tub e has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessme nt of the BORC-system’s efficiency. We obtained 0,84% efficiency for 43,8oC working temper atu e. This corresponds to 35% of the Carnot efficiency calculated for the same temperature diff erence. Limitations of the model and the apparatus are put into perspective, pointing directions for f urther developments of BORC systems.
有机朗肯循环(ORC)系统在可再生能源和可持续能源领域的应用越来越广泛。最近，我们的研究小组发表了一篇论文，确定了一种名为浮力器官朗肯循环(BORC)的新型热力学循环(Schoenmaker et al.， 2011)。在这项工作中，我们提出了两个主要贡献。首先，我们提出了一个考虑工作流体比热的boc系统的精细热力学模型。考虑到改进的模型，在高达100°C的温度下，戊烷和Dic氯甲烷的效率估计为17.2%。其次，我们展示了使用3米高，直径0,062米的聚碳酸酯管作为柱状流体储层的c概念硼砂系统的证明。我们用水作为柱状流体。对整个筒体的热稳定性和均匀性进行了仔细的模拟和实验验证。在水柱的热参数得到充分表征后，我们开发了一个测试体，以充分评估borc系统的效率。我们在43.8℃的工作温度下获得了0.84%的效率。这相当于在相同温差下计算的卡诺效率的35%。对模型和装置的局限性进行了透视，为进一步发展BORC系统指明了方向。
{"title":"Model, simulation and experiments for a Buoyancy Organic Rankine Cycle","authors":"J. Schoenmaker, P. Martins, Guilherme Silva, Júlio, Carlos J C Teixeira","doi":"10.1051/epjap/2020200113","DOIUrl":"https://doi.org/10.1051/epjap/2020200113","url":null,"abstract":"Organic Rankine Cycle (ORC) systems are increasingl y gaining relevance in the renewable and sustainable energy scenario. Recently our research group published a manuscript identifying a new type of thermodynamic cycle entitled Buoyancy Organ ic Rankine Cycle (BORC) (Schoenmaker et al., 2011). In this work we present two main contribut ions. First, we propose a refined thermodynamic model for BORC systems accounting for the specific heat of the working fluid. Considering the refined model, the efficiencies for Pentane and Dic hloromethane at temperatures up to 100°C were estimated to be 17.2%. Second, we show a proof of c oncept BORC system using a 3 m tall, 0,062 m diameter polycarbonate tube as a column-fluid reser voir. We used water as a column fluid. The thermal stability and uniformity throughout the tub e has been carefully simulated and verified experimentally. After the thermal parameters of the water column have been fully characterized, we developed a test body to allow an adequate assessme nt of the BORC-system’s efficiency. We obtained 0,84% efficiency for 43,8oC working temper atu e. This corresponds to 35% of the Carnot efficiency calculated for the same temperature diff erence. Limitations of the model and the apparatus are put into perspective, pointing directions for f urther developments of BORC systems.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76269733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-10-01DOI: 10.1051/epjap/2020200059
Kun Zhang, Qi Gong, Xia Li, Yufeng Su, Z. Duan
In this paper, a miniaturized energy harvester is presented to scavenge gas flow energy. A magnet rotor with three teeth evenly distributed on the edge was introduced into the energy harvester, and it is frictionlessly levitated between two highly oriented pyrolytic graphite (HOPG) sheets. The energy harvester is designed to operate at a single stable equilibrium, so as to improve the stability of the rotor. The optimal incident angle of the gas flow was determined to be 83°. On the basis of the optimal angle, two different configurations of the energy harvester were proposed. Configuration A includes one nozzle, while Configuration B has two centrosymmetric nozzles. The maximum flow rate that enables Configurations A to work stably is limited, which can be increased by thickening the magnet rotor. The maximum voltage of configuration A was 0.28 V at a flow rate of 1500 sccm for the 4.5 mm thick rotor. Configuration B can run stably at any flow rate bigger than 250 sccm and the induced voltage increases with the driving flow rate. At the flow rate of 3000 sccm, the energy harvester of Configuration B can generate a maximum voltage of 3 V and light up tens of light-emitting-diodes (LEDs).
{"title":"A miniaturized gas flow energy harvester using diamagnetically stabilized levitation","authors":"Kun Zhang, Qi Gong, Xia Li, Yufeng Su, Z. Duan","doi":"10.1051/epjap/2020200059","DOIUrl":"https://doi.org/10.1051/epjap/2020200059","url":null,"abstract":"In this paper, a miniaturized energy harvester is presented to scavenge gas flow energy. A magnet rotor with three teeth evenly distributed on the edge was introduced into the energy harvester, and it is frictionlessly levitated between two highly oriented pyrolytic graphite (HOPG) sheets. The energy harvester is designed to operate at a single stable equilibrium, so as to improve the stability of the rotor. The optimal incident angle of the gas flow was determined to be 83°. On the basis of the optimal angle, two different configurations of the energy harvester were proposed. Configuration A includes one nozzle, while Configuration B has two centrosymmetric nozzles. The maximum flow rate that enables Configurations A to work stably is limited, which can be increased by thickening the magnet rotor. The maximum voltage of configuration A was 0.28 V at a flow rate of 1500 sccm for the 4.5 mm thick rotor. Configuration B can run stably at any flow rate bigger than 250 sccm and the induced voltage increases with the driving flow rate. At the flow rate of 3000 sccm, the energy harvester of Configuration B can generate a maximum voltage of 3 V and light up tens of light-emitting-diodes (LEDs).","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79927952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-08DOI: 10.1051/epjap/2020200260
R. Slimani, A. Aissa, Fateh Mebarek-oudina, Umair Khan, M. Sahnoun, Ali J. Chamkha, M. Medebber
The current study investigates MHD natural convection heat transfer of a hybrid nanofluid in a truncated cone along with transparent domains having the stimulus of an inherent constant magnetic field. The governing equations subject to the physical boundary conditions are solved numerically by using the Galerkin finite element method. The effects of the various parameters involved in the problem such as the Rayleigh number Ra (ranging between 103 and 106 ), the Hartmann number Ha (ranging between 0 and 60), and the porosity ratio e (0.1–0.9) are examined. Moreover, the effects of Da which represents the Darcy number (between 10‑3 and 10‑1 ) and the volume fraction of nanoparticles ϕ for the dissipated nanoparticles of Al2 O3- Cu are reported in terms of the streamlines and isotherms distributions as well as the Nusselt number. Such parameters are critical control parameters for both the fluid flow and the rate of heat transfer of the natural convection in the annular space. The solution outcomes proof that the average Nusselt number varies directly with the dynamic field flowing through a porous media, whereas it behaves inversely with the magnetic field.
{"title":"Natural convection analysis flow of Al2O3-Cu/water hybrid nanofluid in a porous conical enclosure subjected to the magnetic field","authors":"R. Slimani, A. Aissa, Fateh Mebarek-oudina, Umair Khan, M. Sahnoun, Ali J. Chamkha, M. Medebber","doi":"10.1051/epjap/2020200260","DOIUrl":"https://doi.org/10.1051/epjap/2020200260","url":null,"abstract":"The current study investigates MHD natural convection heat transfer of a hybrid nanofluid in a truncated cone along with transparent domains having the stimulus of an inherent constant magnetic field. The governing equations subject to the physical boundary conditions are solved numerically by using the Galerkin finite element method. The effects of the various parameters involved in the problem such as the Rayleigh number Ra (ranging between 103 and 106 ), the Hartmann number Ha (ranging between 0 and 60), and the porosity ratio e (0.1–0.9) are examined. Moreover, the effects of Da which represents the Darcy number (between 10‑3 and 10‑1 ) and the volume fraction of nanoparticles ϕ for the dissipated nanoparticles of Al2 O3- Cu are reported in terms of the streamlines and isotherms distributions as well as the Nusselt number. Such parameters are critical control parameters for both the fluid flow and the rate of heat transfer of the natural convection in the annular space. The solution outcomes proof that the average Nusselt number varies directly with the dynamic field flowing through a porous media, whereas it behaves inversely with the magnetic field.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75414382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-03DOI: 10.1051/epjap/2020200067
Tat Lung Wesley Ooi, P. L. Cheang, A. You, Y. Chan
In this work, Monte Carlo model is developed to investigate the avalanche characteristics of GaN and Al0.45 Ga0.55 N avalanche photodiodes (APDs) using random ionization path lengths incorporating dead space effect. The simulation includes the impact ionization coefficients, multiplication gain and excess noise factor for electron- and hole-initiated multiplication with a range of thin multiplication widths. The impact ionization coefficient for GaN is higher than that of Al0.45 Ga0.55 N. For GaN, electron dominates the impact ionization at high electric field while hole dominate at low electric field whereas Al0.45 Ga0.55 N has hole dominate the impact ionization at higher field while electron dominate the lower field. In GaN APDs, electron-initiated multiplication is leading the multiplication gain at thinner multiplication widths while hole-initiated multiplication leads for longer widths. However for Al0.45 Ga0.55 N APDs, hole-initiated multiplication leads the multiplication gain for all multiplication widths simulated. The excess noise of electron-initiated multiplication in GaN APDs increases as multiplication widths increases while the excess noise decreases as the multiplication widths increases for hole-initiated multiplication. As for Al0.45 Ga0.55 N APDs, the excess noise for hole-initiated multiplication increases when multiplication width increases while the electron-initiated multiplication increases with the same gradient at all multiplication widths.
在这项工作中，建立了蒙特卡罗模型来研究GaN和Al0.45 Ga0.55 N雪崩光电二极管(apd)的雪崩特性，采用随机电离路径长度结合死空间效应。仿真包括了在一定宽度范围内电子和空穴激发倍增的冲击电离系数、倍增增益和多余噪声因子。GaN的冲击电离系数高于Al0.45 Ga0.55 N, GaN在高电场下以电子为主，在低电场下以空穴为主，而Al0.45 Ga0.55 N在高电场下以空穴为主，在低电场下以电子为主。在GaN apd中，电子引发的倍增在更薄的倍增宽度处领先倍增增益，而空穴引发的倍增在更长的倍增宽度处领先倍增增益。然而，对于Al0.45 Ga0.55 N apd，在模拟的所有倍增宽度下，孔洞引发的倍增增益都领先于倍增增益。GaN apd中电子引发倍增的过量噪声随着倍增宽度的增大而增大，而空穴引发倍增的过量噪声随着倍增宽度的增大而减小。对于Al0.45 Ga0.55 N apd，空穴引发的倍增噪声随倍增宽度的增加而增加，而电子引发的倍增噪声在所有倍增宽度下都以相同的梯度增加。
{"title":"Mean multiplication gain and excess noise factor of GaN and Al0.45Ga0.55N avalanche photodiodes","authors":"Tat Lung Wesley Ooi, P. L. Cheang, A. You, Y. Chan","doi":"10.1051/epjap/2020200067","DOIUrl":"https://doi.org/10.1051/epjap/2020200067","url":null,"abstract":"In this work, Monte Carlo model is developed to investigate the avalanche characteristics of GaN and Al0.45 Ga0.55 N avalanche photodiodes (APDs) using random ionization path lengths incorporating dead space effect. The simulation includes the impact ionization coefficients, multiplication gain and excess noise factor for electron- and hole-initiated multiplication with a range of thin multiplication widths. The impact ionization coefficient for GaN is higher than that of Al0.45 Ga0.55 N. For GaN, electron dominates the impact ionization at high electric field while hole dominate at low electric field whereas Al0.45 Ga0.55 N has hole dominate the impact ionization at higher field while electron dominate the lower field. In GaN APDs, electron-initiated multiplication is leading the multiplication gain at thinner multiplication widths while hole-initiated multiplication leads for longer widths. However for Al0.45 Ga0.55 N APDs, hole-initiated multiplication leads the multiplication gain for all multiplication widths simulated. The excess noise of electron-initiated multiplication in GaN APDs increases as multiplication widths increases while the excess noise decreases as the multiplication widths increases for hole-initiated multiplication. As for Al0.45 Ga0.55 N APDs, the excess noise for hole-initiated multiplication increases when multiplication width increases while the electron-initiated multiplication increases with the same gradient at all multiplication widths.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86827138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-03DOI: 10.1051/epjap/2020200154
R. Temsamani, A. Talbi, A. Mrigal, M. Addou, K. Nouneh, Karima Guedouch, H. Zaari
Optical, structural and electronic properties of vanadium pentoxide (V2O5) thin films deposited with different values of substrate temperature have been investigated. First principles calculations were performed using the Full Potential Projector-Augmented Wave (PAW) method with the Generalized Gradient Approximation (GGA) implemented in Quantum Espresso code. The results are very promising and show that the temperature has an important effect on V2O5 thin films features. Dielectric functions for different thin films are calculated for 14-atom orthorhombic super-cell structure. The calculated band gaps are fitted with a linear equation: (αhv) 2 = A (hv − Eg) . For all types of deposited thin films the position of critical points (CPs) E0, E1 and E2 show good agreement with the experimental data.
研究了不同衬底温度下沉积的五氧化钒(V2O5)薄膜的光学、结构和电子性能。使用全势投影增强波(PAW)方法进行第一性原理计算，并在Quantum Espresso代码中实现了广义梯度近似(GGA)。结果表明，温度对V2O5薄膜的特性有重要影响。计算了14原子正交超电池结构不同薄膜的介电函数。计算得到的带隙符合线性方程:(αhv) 2 = a (hv−Eg)。对于所有类型的沉积薄膜，临界点(CPs) E0、E1和E2的位置与实验数据吻合较好。
{"title":"Substrate temperature effect on structural, electronic and optical properties of V2O5 thin films: experimental and ab initio study","authors":"R. Temsamani, A. Talbi, A. Mrigal, M. Addou, K. Nouneh, Karima Guedouch, H. Zaari","doi":"10.1051/epjap/2020200154","DOIUrl":"https://doi.org/10.1051/epjap/2020200154","url":null,"abstract":"Optical, structural and electronic properties of vanadium pentoxide (V2O5) thin films deposited with different values of substrate temperature have been investigated. First principles calculations were performed using the Full Potential Projector-Augmented Wave (PAW) method with the Generalized Gradient Approximation (GGA) implemented in Quantum Espresso code. The results are very promising and show that the temperature has an important effect on V2O5 thin films features. Dielectric functions for different thin films are calculated for 14-atom orthorhombic super-cell structure. The calculated band gaps are fitted with a linear equation: (αhv) 2 = A (hv − Eg) . For all types of deposited thin films the position of critical points (CPs) E0, E1 and E2 show good agreement with the experimental data.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78464222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.1051/epjap/2020200144
Zhen-wei Zhou, Xi-guang Wang, Yao Nie, Q. Xia, G. Guo
Efficient excitation of spin waves is a key issue in magnonics. Here, by using micromagnetic simulation and analytical analysis, we study the excitation of spin waves confined in a limited region by a microwave field with assistance of spin-transfer torque. The results show that the spin-transfer torque can decrease the effective damping constant and increase the spin wave relaxation time substantially. As a result, the amplitude of the excited spin waves is increased greatly. By periodically lifting and establishing the blocking areas, strong spin-wave pulses are released from the confined region. Such generated spin-wave pulses are much stronger than traditionally excited spin waves, especially for high-frequency spin waves. Our study provides a new method to generate strong high-frequency spin waves.
{"title":"Strong high-frequency spin waves released periodically from a confined region","authors":"Zhen-wei Zhou, Xi-guang Wang, Yao Nie, Q. Xia, G. Guo","doi":"10.1051/epjap/2020200144","DOIUrl":"https://doi.org/10.1051/epjap/2020200144","url":null,"abstract":"Efficient excitation of spin waves is a key issue in magnonics. Here, by using micromagnetic simulation and analytical analysis, we study the excitation of spin waves confined in a limited region by a microwave field with assistance of spin-transfer torque. The results show that the spin-transfer torque can decrease the effective damping constant and increase the spin wave relaxation time substantially. As a result, the amplitude of the excited spin waves is increased greatly. By periodically lifting and establishing the blocking areas, strong spin-wave pulses are released from the confined region. Such generated spin-wave pulses are much stronger than traditionally excited spin waves, especially for high-frequency spin waves. Our study provides a new method to generate strong high-frequency spin waves.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73986938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.1051/epjap/2020200136
M. Al-Hattab, L. Moudou, Y. Chrafih, M. Khenfouch, O. Bajjou, K. Rahmani
In this paper, we have calculated the optical properties of the different polytypes of GaSe lamellar materials. The calculations are based on the DFT method and is performed using the CASTEP code. All optical properties have been studied in a domain that extends energetically from 10 meV to 35 eV and have been measured for a polarization // and ⊥ with the c axis. A strong anisotropic was observed, which indicates that the optical properties of the GaSe material are essentially determined by the symmetry of a single layer, exactly by the symmetry resulting from the stacking of the layers. Moreover, the absorption starts in the UV–vis spectral range, the peaks appear in the UV range. The refractive index values are n xx = 2.54, 2.55, 2.88, 10.85, n zz = 3.90, 3.90, 3.26, 11.73 for e , β , γ , δ , respectively at zero photon energy. Furthermore, we notice that the optical properties of different polytypes (e , β , δ , γ ) of GaSe lamellar materials are obtained both in the ultraviolet field or in the visible domain are significant and give a strong argument for the use of these materials in various applications, namely photovoltaic cells, nanoelectronic, optoelectronic, optical fiber and photo-catalytic applications.
{"title":"The anisotropic optical properties of different polytypes (ε, β, δ, γ) of GaSe lamellar materials","authors":"M. Al-Hattab, L. Moudou, Y. Chrafih, M. Khenfouch, O. Bajjou, K. Rahmani","doi":"10.1051/epjap/2020200136","DOIUrl":"https://doi.org/10.1051/epjap/2020200136","url":null,"abstract":"In this paper, we have calculated the optical properties of the different polytypes of GaSe lamellar materials. The calculations are based on the DFT method and is performed using the CASTEP code. All optical properties have been studied in a domain that extends energetically from 10 meV to 35 eV and have been measured for a polarization // and ⊥ with the c axis. A strong anisotropic was observed, which indicates that the optical properties of the GaSe material are essentially determined by the symmetry of a single layer, exactly by the symmetry resulting from the stacking of the layers. Moreover, the absorption starts in the UV–vis spectral range, the peaks appear in the UV range. The refractive index values are n xx = 2.54, 2.55, 2.88, 10.85, n zz = 3.90, 3.90, 3.26, 11.73 for e , β , γ , δ , respectively at zero photon energy. Furthermore, we notice that the optical properties of different polytypes (e , β , δ , γ ) of GaSe lamellar materials are obtained both in the ultraviolet field or in the visible domain are significant and give a strong argument for the use of these materials in various applications, namely photovoltaic cells, nanoelectronic, optoelectronic, optical fiber and photo-catalytic applications.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88244690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.1051/epjap/2020190286
R. Tidecks
Recent experimental studies and modelling of the mercury loss (i.e. the mercury consumption) in fluorescent lamps yield diffusion coefficients of mobile mercury in phosphor layers and coatings, which are several orders of magnitude smaller than expected for a gas diffusion in a situation in which the mean free path of the diffusing particles is restricted by the pore radius in those materials (Knudsen diffusion). In the present work it is shown that the transition of mercury ions from the plasma to the Knudsen diffusion regime may be one reason for this observation. Another possibility is that only discharged ions from the plasma form the mercury oxide as which mercury is deposited in the phosphor layer and coating, from the investigation of which the diffusion coefficient of mobile mercury is concluded by fitting the model to the experiment.
{"title":"Evidence for electron-tunneling-limited Knudsen diffusion of mercury in phosphor layers and coatings of fluorescent lamps","authors":"R. Tidecks","doi":"10.1051/epjap/2020190286","DOIUrl":"https://doi.org/10.1051/epjap/2020190286","url":null,"abstract":"Recent experimental studies and modelling of the mercury loss (i.e. the mercury consumption) in fluorescent lamps yield diffusion coefficients of mobile mercury in phosphor layers and coatings, which are several orders of magnitude smaller than expected for a gas diffusion in a situation in which the mean free path of the diffusing particles is restricted by the pore radius in those materials (Knudsen diffusion). In the present work it is shown that the transition of mercury ions from the plasma to the Knudsen diffusion regime may be one reason for this observation. Another possibility is that only discharged ions from the plasma form the mercury oxide as which mercury is deposited in the phosphor layer and coating, from the investigation of which the diffusion coefficient of mobile mercury is concluded by fitting the model to the experiment.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75683172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.1051/epjap/2020200130
Nadia El Harfaouia, Y. Khaaissa, K. Nouneh, A. Belahmar, A. Talbi, K. El Mabrouk, R. Hsissou, E. Feddi, A. Taleb, A. El Mouakibi
Dense layer of silver nanoparticles (AgNPs) was successfully prepared on indium tin oxide (ITO) surfaces by using a refined seed-mediated growth approach (RSMG). Prepared AgNPs/ITO film was investigated using several methods such as UV–vis spectroscopy, field emission scanning electron microscope, optical absorption, electrochemical impedance spectroscopy and cyclic voltammeter. The size and density of AgNPs on ITO surface were investigated and their governing parameters were discussed. The obtained results by using refined seed-mediated growth approach showed a narrower size distribution and a higher density of prepared AgNPs compared to those prepared by the normal seed-mediated growth method. The size of AgNPs was controlled by adjusting the growth time until 2 h, while if it is higher than 3 h, larger AgNPs with anisotropic shape were formed. Cysteamine molecules were used to ensure the attachment of AgNPs on the ITO surface and it was found to be effective for preparing dense and dispersed Ag NPs on ITO surface. The optical properties of prepared AgNPs layer with different density on the ITO surface were studied and discussed, using the full Mie theory for scattering and absorption by a homogeneous Ag sphere with modified dielectric constants.
{"title":"One pot synthesis of silver nanoparticles on ITO surfaces: investigation of optical and electrochemical properties","authors":"Nadia El Harfaouia, Y. Khaaissa, K. Nouneh, A. Belahmar, A. Talbi, K. El Mabrouk, R. Hsissou, E. Feddi, A. Taleb, A. El Mouakibi","doi":"10.1051/epjap/2020200130","DOIUrl":"https://doi.org/10.1051/epjap/2020200130","url":null,"abstract":"Dense layer of silver nanoparticles (AgNPs) was successfully prepared on indium tin oxide (ITO) surfaces by using a refined seed-mediated growth approach (RSMG). Prepared AgNPs/ITO film was investigated using several methods such as UV–vis spectroscopy, field emission scanning electron microscope, optical absorption, electrochemical impedance spectroscopy and cyclic voltammeter. The size and density of AgNPs on ITO surface were investigated and their governing parameters were discussed. The obtained results by using refined seed-mediated growth approach showed a narrower size distribution and a higher density of prepared AgNPs compared to those prepared by the normal seed-mediated growth method. The size of AgNPs was controlled by adjusting the growth time until 2 h, while if it is higher than 3 h, larger AgNPs with anisotropic shape were formed. Cysteamine molecules were used to ensure the attachment of AgNPs on the ITO surface and it was found to be effective for preparing dense and dispersed Ag NPs on ITO surface. The optical properties of prepared AgNPs layer with different density on the ITO surface were studied and discussed, using the full Mie theory for scattering and absorption by a homogeneous Ag sphere with modified dielectric constants.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88042778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-09-01DOI: 10.1051/epjap/2020200163
Aiqiang Chen, Xin Chen, X. Miao, Jinghong Yin, B. Liu
The evolution of an evaporating liquid on another nonmiscible fluid is important for many applications. An experimental study on the evaporation process of hexane lens on the surface of deionized water at different temperatures was carried out, and the surface temperature distribution characteristics and internal flow pattern evolution was analyzed. Results show that the surface temperature of hexane lens can be divided into two parts or three areas depending on the temperature of deionized water. The increasing temperature of deionized water gradually changes both vertical temperature gradient and radial temperature gradient inside hexane lens, and their competition determines the flow pattern inside the hexane lens. Flow along hexane edge caused by circumferential surface tension gradient forms a “low temperature channel” between the central low temperature region and the strong evaporation edge. The knowledge will benefit the fundamental understanding of evaporation characteristics of volatile droplets on a liquid surface.
{"title":"Experimental study on the evaporating progress of hexane lenses on water surface with different temperature","authors":"Aiqiang Chen, Xin Chen, X. Miao, Jinghong Yin, B. Liu","doi":"10.1051/epjap/2020200163","DOIUrl":"https://doi.org/10.1051/epjap/2020200163","url":null,"abstract":"The evolution of an evaporating liquid on another nonmiscible fluid is important for many applications. An experimental study on the evaporation process of hexane lens on the surface of deionized water at different temperatures was carried out, and the surface temperature distribution characteristics and internal flow pattern evolution was analyzed. Results show that the surface temperature of hexane lens can be divided into two parts or three areas depending on the temperature of deionized water. The increasing temperature of deionized water gradually changes both vertical temperature gradient and radial temperature gradient inside hexane lens, and their competition determines the flow pattern inside the hexane lens. Flow along hexane edge caused by circumferential surface tension gradient forms a “low temperature channel” between the central low temperature region and the strong evaporation edge. The knowledge will benefit the fundamental understanding of evaporation characteristics of volatile droplets on a liquid surface.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":null,"pages":null},"PeriodicalIF":1.0,"publicationDate":"2020-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79782306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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