Pub Date : 2020-11-01DOI: 10.1051/epjap/2020200223
A. Labrag, M. Bghour, Ahmed Abou El Hassan, Habiba El Hamidi, A. Taoufik, Said Laasri
It is reported in this paper on the thermally assisted flux flow in epitaxial YBa2 Cu3 O7-δ deposited by Laser ablation method on the SrTiO3 substrate. The resistivity measurements ρ (T , B ) of the sample under various values of the magnetic field up to 14T in directions B ∥ab-plane and B ∥c -axis with a dc weak transport current density were investigated in order to determine the activation energy and then understand the vortex dynamic phenomena and therefore deduce the vortex phase diagram of this material. The apparent activation energy U 0 (B ) calculated using an Arrhenius relation. The measured results of the resistivity were then adjusted to the modified thermally assisted flux flow model in order to account for the temperature-field dependence of the activation energy U (T , B ). The obtained values from the thermally assisted activation energy, exhibit a behavior similar to the one showed with the Arrhenius model, albeit larger than the apparent activation energy with ∼1.5 order on magnitude for both cases of the magnetic field directions. The vortex glass model was also used to obtain the vortex-glass transition temperature from the linear fitting of [d ln ρ /dT ] −1 plots. In the course of this work thanks to the resistivity measurements the upper critical magnetic field H c 2 (T ), the irreversibility line H irr (T ) and the crossover field H CrossOver (T ) were located. These three parameters allowed us to establish a phase diagram of the studied material where limits of each vortex phase are sketched in order to optimize its applicability as a practical high temperature superconductor used for diverse purposes.
{"title":"The activation energy U(T,B) in high temperature superconductor","authors":"A. Labrag, M. Bghour, Ahmed Abou El Hassan, Habiba El Hamidi, A. Taoufik, Said Laasri","doi":"10.1051/epjap/2020200223","DOIUrl":"https://doi.org/10.1051/epjap/2020200223","url":null,"abstract":"It is reported in this paper on the thermally assisted flux flow in epitaxial YBa2 Cu3 O7-δ deposited by Laser ablation method on the SrTiO3 substrate. The resistivity measurements ρ (T , B ) of the sample under various values of the magnetic field up to 14T in directions B ∥ab-plane and B ∥c -axis with a dc weak transport current density were investigated in order to determine the activation energy and then understand the vortex dynamic phenomena and therefore deduce the vortex phase diagram of this material. The apparent activation energy U 0 (B ) calculated using an Arrhenius relation. The measured results of the resistivity were then adjusted to the modified thermally assisted flux flow model in order to account for the temperature-field dependence of the activation energy U (T , B ). The obtained values from the thermally assisted activation energy, exhibit a behavior similar to the one showed with the Arrhenius model, albeit larger than the apparent activation energy with ∼1.5 order on magnitude for both cases of the magnetic field directions. The vortex glass model was also used to obtain the vortex-glass transition temperature from the linear fitting of [d ln ρ /dT ] −1 plots. In the course of this work thanks to the resistivity measurements the upper critical magnetic field H c 2 (T ), the irreversibility line H irr (T ) and the crossover field H CrossOver (T ) were located. These three parameters allowed us to establish a phase diagram of the studied material where limits of each vortex phase are sketched in order to optimize its applicability as a practical high temperature superconductor used for diverse purposes.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"40 1","pages":"20601"},"PeriodicalIF":1.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79875371","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 : 2020-11-01DOI: 10.1051/epjap/2020200208
Behrokh Beiranvand, A. Sobolev, A. V. Kudryashov
We present a new concept of the thermoelectric structure that generates microwave and terahertz signals when illuminated by femtosecond optical pulses. The structure consists of a series array of capacitively coupled thermocouples. The array acts as a hybrid type microwave transmission line with anomalous dispersion and phase velocity higher than the velocity of light. This allows for adding up the responces from all the thermocouples in phase. The array is easily integrable with microstrip transmission lines. Dispersion curves obtained from both the lumped network scheme and numerical simulations are presented. The connection of the thermocouples is a composite right/left-handed transmission line, which can receive terahertz radiation from the transmission line ports. The radiation of the photon to the surface of the thermocouple structure causes a voltage difference with the bandwidth of terahertz. We examined a lossy composite right/left-handed transmission line to extract the circuit elements. The calculated properties of the design are extracted by employing commercial software package CST STUDIO SUITE.
我们提出了一个新的概念，热电结构产生微波和太赫兹信号时，由飞秒光脉冲照射。该结构由一系列电容耦合热电偶阵列组成。该阵列作为一种异常色散且相速度高于光速的混合型微波传输线。这允许将所有热电偶的响应加起来。该阵列易于与微带传输线集成。给出了集总网络方案和数值模拟得到的色散曲线。热电偶的连接是一条复合的右/左传输线，可以接收来自传输线端口的太赫兹辐射。光子对热电偶结构表面的辐射会产生带宽为太赫兹的电压差。我们检查了一个有损复合右/左传输线来提取电路元件。利用商业软件包CST STUDIO SUITE对设计的计算属性进行提取。
{"title":"Composite right/left-handed transmission line with array of thermocouples for generating terahertz radiation","authors":"Behrokh Beiranvand, A. Sobolev, A. V. Kudryashov","doi":"10.1051/epjap/2020200208","DOIUrl":"https://doi.org/10.1051/epjap/2020200208","url":null,"abstract":"We present a new concept of the thermoelectric structure that generates microwave and terahertz signals when illuminated by femtosecond optical pulses. The structure consists of a series array of capacitively coupled thermocouples. The array acts as a hybrid type microwave transmission line with anomalous dispersion and phase velocity higher than the velocity of light. This allows for adding up the responces from all the thermocouples in phase. The array is easily integrable with microstrip transmission lines. Dispersion curves obtained from both the lumped network scheme and numerical simulations are presented. The connection of the thermocouples is a composite right/left-handed transmission line, which can receive terahertz radiation from the transmission line ports. The radiation of the photon to the surface of the thermocouple structure causes a voltage difference with the bandwidth of terahertz. We examined a lossy composite right/left-handed transmission line to extract the circuit elements. The calculated properties of the design are extracted by employing commercial software package CST STUDIO SUITE.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"1 1","pages":"20502"},"PeriodicalIF":1.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82401513","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 : 2020-11-01DOI: 10.1051/epjap/2020200201
K. Benthami, M. Barakat, S. Nouh
Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2 O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2 O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2 O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2 O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2 O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2 O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.
{"title":"Modification of optical properties of PC-PBT/Cr2O3 and PC-PBT/CdS nanocomposites by gamma irradiation","authors":"K. Benthami, M. Barakat, S. Nouh","doi":"10.1051/epjap/2020200201","DOIUrl":"https://doi.org/10.1051/epjap/2020200201","url":null,"abstract":"Nanocomposite (NCP) films of polycarbonate-polybutylene terephthalate (PC-PBT) blend as a host material to Cr2 O3 and CdS nanoparticles (NPs) were fabricated by both thermolysis and casting techniques. Samples from the PC-PBT/Cr2 O3 and PC-PBT/CdS NCPs were irradiated using different doses (20–110 kGy) of γ radiation. The induced modifications in the optical properties of the γ irradiated NCPs have been studied as a function of γ dose using UV Vis spectroscopy and CIE color difference method. Optical dielectric loss and Tauc's model were used to estimate the optical band gaps of the NCP films and to identify the types of electronic transition. The value of optical band gap energy of PC-PBT/Cr2 O3 NCP was reduced from 3.23 to 3.06 upon γ irradiation up to 110 kGy, while it decreased from 4.26 to 4.14 eV for PC-PBT/CdS NCP, indicating the growth of disordered phase in both NCPs. This was accompanied by a rise in the refractive index for both the PC-PBT/Cr2 O3 and PC-PBT/CdS NCP films, leading to an enhancement in their isotropic nature. The Cr2 O3 NPs were found to be more effective in changing the band gap energy and refractive index due to the presence of excess oxygen atoms that help with the oxygen atoms of the carbonyl group in increasing the chance of covalent bonds formation between the NPs and the PC-PBT blend. Moreover, the color intensity, ΔE has been computed; results show that both the two synthesized NCPs have a response to color alteration by γ irradiation, but the PC-PBT/Cr2 O3 has a more response since the values of ΔE achieved a significant color difference >5 which is an acceptable match in commercial reproduction on printing presses. According to the resulting enhancement in the optical characteristics of the developed NCPs, they can be a suitable candidate as activate materials in optoelectronic devices, or shielding sheets for solar cells.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"3 1","pages":"20402"},"PeriodicalIF":1.0,"publicationDate":"2020-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90202065","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/2020200179
S. Boufass, A. Hader, M. Tanasehte, H. Sbiaai, I. Achik, Y. Boughaleb
In this paper, the fiber energy in composite materials, subject to an external constant load, is studied. The investigation is done in the framework of fiber bundle model with randomly oriented fibers. The charge transfer is done only between neighboring close fibers according to the local load sharing. During the breaking process, the fibers expand, increasing their elastic energy, but when the fiber breaks, it loses its link with its neighboring fibers reducing the cohesive energy of the materials. The results show that the material energy presents one maximal peak at cross over time which decreases linearly with the applied force and scales with the lifetime of the material. However, the temperature does not have a remarkable effect on the material energy variation. In addition, the link density fiber decreases exponentially with time. The characteristic time of the obtained profile decreases with the applied force. Moreover, this density decreases with applied forces according to the Lorentz law with a remarkable change at critical force value.
{"title":"Modelling of composite materials energy by fiber bundle model","authors":"S. Boufass, A. Hader, M. Tanasehte, H. Sbiaai, I. Achik, Y. Boughaleb","doi":"10.1051/epjap/2020200179","DOIUrl":"https://doi.org/10.1051/epjap/2020200179","url":null,"abstract":"In this paper, the fiber energy in composite materials, subject to an external constant load, is studied. The investigation is done in the framework of fiber bundle model with randomly oriented fibers. The charge transfer is done only between neighboring close fibers according to the local load sharing. During the breaking process, the fibers expand, increasing their elastic energy, but when the fiber breaks, it loses its link with its neighboring fibers reducing the cohesive energy of the materials. The results show that the material energy presents one maximal peak at cross over time which decreases linearly with the applied force and scales with the lifetime of the material. However, the temperature does not have a remarkable effect on the material energy variation. In addition, the link density fiber decreases exponentially with time. The characteristic time of the obtained profile decreases with the applied force. Moreover, this density decreases with applied forces according to the Lorentz law with a remarkable change at critical force value.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"71 1","pages":"10401"},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90811946","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/2020200171
A. Alaoui-Belghiti, Y. Tabbai, M. Rkhis, S. Laasri, H. Lifi, A. Laghzizil, K. Strzałkowski, A. Hajjaji
Ceramics arising from Pb(Mg1/3 Nb2/3 )1‑x Tix O3 with composition near the morphotropic phase boundary (MPB) were prepared by the modified solid-state reaction method. The synthesized ceramics were characterized, and then the operating principles of pyroelectric and piezoelectric harvesters are reviewed. In addition, the dielectric behavior is measured to determine the dielectric constant and losses at different temperatures and frequencies. The typical behavior of a ferroelectric relaxer was observed by adding the PbTiO3 phase. The thermal properties are also analyzed by PPE calorimetry, presaging a one-dimensional heat-flow process. As a result, the dielectric and thermal behaviors of the as-prepared ceramics as well as their thermal stability are intimately linked to the PbTiO3 addition to PbMgl/3 Nb2/3 O3 phase. These materials exhibit good physical performances, which makes them promising candidates for pyroelectric micro-generators (PEG), cooling systems and infrared applications.
{"title":"Structural, thermal and dielectric properties of Pb(Mg1/3Nb2/3)1‑x TixO3 ceramics at morphotropic phase boundary","authors":"A. Alaoui-Belghiti, Y. Tabbai, M. Rkhis, S. Laasri, H. Lifi, A. Laghzizil, K. Strzałkowski, A. Hajjaji","doi":"10.1051/epjap/2020200171","DOIUrl":"https://doi.org/10.1051/epjap/2020200171","url":null,"abstract":"Ceramics arising from Pb(Mg1/3 Nb2/3 )1‑x Tix O3 with composition near the morphotropic phase boundary (MPB) were prepared by the modified solid-state reaction method. The synthesized ceramics were characterized, and then the operating principles of pyroelectric and piezoelectric harvesters are reviewed. In addition, the dielectric behavior is measured to determine the dielectric constant and losses at different temperatures and frequencies. The typical behavior of a ferroelectric relaxer was observed by adding the PbTiO3 phase. The thermal properties are also analyzed by PPE calorimetry, presaging a one-dimensional heat-flow process. As a result, the dielectric and thermal behaviors of the as-prepared ceramics as well as their thermal stability are intimately linked to the PbTiO3 addition to PbMgl/3 Nb2/3 O3 phase. These materials exhibit good physical performances, which makes them promising candidates for pyroelectric micro-generators (PEG), cooling systems and infrared applications.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"54 1","pages":"10902"},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83414738","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/2020200161
Saloua El Asri, H. Ahamdane, L. Hajji, M. Hadri, Moulay Ahmed El Idrissi Raghni, M. Mansori
Forsterite single phase powder Mg2 SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2 SiO4 . The formation of forsterite started at 680–740 °C and at 630–700 °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.
{"title":"Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite","authors":"Saloua El Asri, H. Ahamdane, L. Hajji, M. Hadri, Moulay Ahmed El Idrissi Raghni, M. Mansori","doi":"10.1051/epjap/2020200161","DOIUrl":"https://doi.org/10.1051/epjap/2020200161","url":null,"abstract":"Forsterite single phase powder Mg2 SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2 SiO4 . The formation of forsterite started at 680–740 °C and at 630–700 °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"8 1","pages":"10901"},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81373352","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/2020200020
R. Zeinali, D. Krop, E. Lomonova
A new magneto-dynamic model is proposed to approximate the dynamic hysteresis effect in laminated steels considering the static hysteresis, eddy-current field, and excess field. An accurate congruency-based hysteresis model is used to predict the static hysteresis field. The eddy-current is determined from the 1D diffusion equation and the well-known Bertotti empirical equation is utilized to model the excess-field effect. The dynamic lamination model obtained from coupling three field components is solved using a Fourier-based approach. In this approach, the flux density across the lamination thickness is approximated by a cosine-based Fourier series. The coefficients of the Fourier series are determined by solving a system of nonlinear equations through an iterative procedure. Owing to the employed congruency-based static hysteresis model, the proposed magneto-dynamic model offers high accuracy for arbitrary magnetization regimes. To validate the model accuracy, the model results are compared with sinusoidal and multi-harmonic measurements. The comparison shows that the proposed model predicts the dynamic hysteresis phenomenon in laminated steels with a relative energy error of less than 7%.
{"title":"Modeling the dynamic behavior of laminated steels using a Fourier-based approach","authors":"R. Zeinali, D. Krop, E. Lomonova","doi":"10.1051/epjap/2020200020","DOIUrl":"https://doi.org/10.1051/epjap/2020200020","url":null,"abstract":"A new magneto-dynamic model is proposed to approximate the dynamic hysteresis effect in laminated steels considering the static hysteresis, eddy-current field, and excess field. An accurate congruency-based hysteresis model is used to predict the static hysteresis field. The eddy-current is determined from the 1D diffusion equation and the well-known Bertotti empirical equation is utilized to model the excess-field effect. The dynamic lamination model obtained from coupling three field components is solved using a Fourier-based approach. In this approach, the flux density across the lamination thickness is approximated by a cosine-based Fourier series. The coefficients of the Fourier series are determined by solving a system of nonlinear equations through an iterative procedure. Owing to the employed congruency-based static hysteresis model, the proposed magneto-dynamic model offers high accuracy for arbitrary magnetization regimes. To validate the model accuracy, the model results are compared with sinusoidal and multi-harmonic measurements. The comparison shows that the proposed model predicts the dynamic hysteresis phenomenon in laminated steels with a relative energy error of less than 7%.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"11 1","pages":"10905"},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89477024","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/2020190363
R. Langer, R. Tidecks
In the present work the temperature dependence of the work function of oxide cathodes in operating fluorescent lamps was investigated experimentally. A detailed review on the theory is presented, including a thermodynamic and a quantum mechanical view on the problem. Aspects such as the role of the electrochemical potential, external and internal potentials, the constituents of the electron affinity, the patch effect and surface states are discussed. For solids in contact the Volta and Galvani potentials are related to their work functions. The importance of colour centres in oxide electrodes on the temperature dependence of the work function and the impact of ultraviolet radiation is emphasized. The measurements have been carried out under zero field emission of electrons from the electrode, using the Waymouth (rf) and Eisenmann (visual) methods as indicators. By inserting an empirical ansatz into the Richardson equation, it was possible to determine the temperature dependence of the work function from the experiments.
{"title":"The temperature dependence of the work function of oxide electrodes in fluorescent lamps","authors":"R. Langer, R. Tidecks","doi":"10.1051/epjap/2020190363","DOIUrl":"https://doi.org/10.1051/epjap/2020190363","url":null,"abstract":"In the present work the temperature dependence of the work function of oxide cathodes in operating fluorescent lamps was investigated experimentally. A detailed review on the theory is presented, including a thermodynamic and a quantum mechanical view on the problem. Aspects such as the role of the electrochemical potential, external and internal potentials, the constituents of the electron affinity, the patch effect and surface states are discussed. For solids in contact the Volta and Galvani potentials are related to their work functions. The importance of colour centres in oxide electrodes on the temperature dependence of the work function and the impact of ultraviolet radiation is emphasized. The measurements have been carried out under zero field emission of electrons from the electrode, using the Waymouth (rf) and Eisenmann (visual) methods as indicators. By inserting an empirical ansatz into the Richardson equation, it was possible to determine the temperature dependence of the work function from the experiments.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"72 1","pages":"11301"},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84490890","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/2020200168
B. Liu, Wang Shengwei, Lin Chai, G. E. Achkar, Aiqiang Chen, P. Theodorakis
Droplet evaporation is fascinating, ubiquitous, and relevant for a wide spectrum of applications, such as printing, drug testing, coating, and biomedical diagnosis. In this paper, the effects of substrate temperature (30 °C, 47 °C, 64 °C, 81 °C) and 20 nm Al2 O3 nanoparticles mass fraction (0.05%, 0.1%, 0.2%) on the nanoparticles distribution mechanisms and deposition patterns during the evaporation of Al2 O3 -H2 O nanofluid droplet were experimentally investigated. An experimental device was designed and realized. The self-assembly and Marangoni forces were first highlighted and compared. Two coffee-ring and inner-ring patterns were then identified and analyzed. The evaporation process characteristics were finally determined and discussed.
{"title":"Experimental investigation of nanoparticles distribution mechanisms and deposition patterns during nanofluid droplet evaporation","authors":"B. Liu, Wang Shengwei, Lin Chai, G. E. Achkar, Aiqiang Chen, P. Theodorakis","doi":"10.1051/epjap/2020200168","DOIUrl":"https://doi.org/10.1051/epjap/2020200168","url":null,"abstract":"Droplet evaporation is fascinating, ubiquitous, and relevant for a wide spectrum of applications, such as printing, drug testing, coating, and biomedical diagnosis. In this paper, the effects of substrate temperature (30 °C, 47 °C, 64 °C, 81 °C) and 20 nm Al2 O3 nanoparticles mass fraction (0.05%, 0.1%, 0.2%) on the nanoparticles distribution mechanisms and deposition patterns during the evaporation of Al2 O3 -H2 O nanofluid droplet were experimentally investigated. An experimental device was designed and realized. The self-assembly and Marangoni forces were first highlighted and compared. Two coffee-ring and inner-ring patterns were then identified and analyzed. The evaporation process characteristics were finally determined and discussed.","PeriodicalId":12228,"journal":{"name":"European Physical Journal-applied Physics","volume":"7 1","pages":"11101"},"PeriodicalIF":1.0,"publicationDate":"2020-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89619676","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/2020200098
L. Shaginyan, V. Shaginyan, A. Kuzmichev, M. Mironov
New simple method for target surface temperature (TST) measurements is successfully developed and described in detail. Along with temperature measurements we measured also the emissivity of each of targets by the method specially developed for this aim. The measurements demonstrate that the surface temperature of the targets prepared from Cu, Mo, Nb discs may substantially (up to ∼300 °C) exceed the temperature of the volume of the target. The definition of a “target surface temperature” is given. It is supposed that the thickness of the surface layer that appears on a target subjected to the ion bombardment is equal or close to the penetration depth of ions bombarding the target. The physical model explaining the formation of the surface layer is suggested. The main idea of the model is that the Ar ions bombarding the target may effectively transfer their kinetic energy mostly to the ionic subsystem rather than to the electron subsystem of a target. Due to very low mobility of metal ions within the layer the thermal conductivity of the layer is substantially lower compared to the rest target volume. As a result the temperature of the layer is higher than that of the rest part of the target.
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