Pub Date : 2023-09-01DOI: 10.31349/revmexfis.69.051301
Jesus Pablo Lauterio-Cruz, J. Manzanares Martínez, J. A. Gaspar Armenta
In this paper, we provide a theoretical prediction about the likelihood of producing high-order modes using, as far as we know, the simplest mode converter. The mode converter is a simple discontinuous waveguide for which reflection and transmission have recently been reported. As a result of the scattering of the fundamental guided mode (TE0), we have found that the high-order mode excitation is highly dependent on the position of the discontinuity. On the one hand, we discovered that in the presence of a discontinuity in the propagation direction, only even modes (TE0 and TE2) are excited, skipping the odd mode (TE1). When a lateral shift is considered, however, both even and odd higher-order modes (TE1 and TE2) are generated. Furthermore, after some lateral shifting, we found that only the pure TE2 mode is propagated.
{"title":"Higher order mode conversion induced by discontinuities in waveguides","authors":"Jesus Pablo Lauterio-Cruz, J. Manzanares Martínez, J. A. Gaspar Armenta","doi":"10.31349/revmexfis.69.051301","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051301","url":null,"abstract":"In this paper, we provide a theoretical prediction about the likelihood of producing high-order modes using, as far as we know, the simplest mode converter. The mode converter is a simple discontinuous waveguide for which reflection and transmission have recently been reported. As a result of the scattering of the fundamental guided mode (TE0), we have found that the high-order mode excitation is highly dependent on the position of the discontinuity. On the one hand, we discovered that in the presence of a discontinuity in the propagation direction, only even modes (TE0 and TE2) are excited, skipping the odd mode (TE1). When a lateral shift is considered, however, both even and odd higher-order modes (TE1 and TE2) are generated. Furthermore, after some lateral shifting, we found that only the pure TE2 mode is propagated.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48468049","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 : 2023-09-01DOI: 10.31349/revmexfis.69.051004
Brach Brach, L. Bahmad, S. Benyoussef
In this article, we examine the structure, electronic, optical, and magnetic properties of ZnTe before and after doping with the transition metal Mn. The ab initio calculations of this compound were performed using the full potential linearized extended full potential planar waveform (FP-LAPW) in the context of density functional theory (DFT) implemented in the Wien2K code. The potential for exchange and correlation was addressed by the GGA approximation. The electronic properties show that the ZnTe material exhibits semiconductor behavior before doping and it becomes semimetal after doping. The findings attained by Monte Carlo simulations display that the ZnMnTe material goes from an antiferromagnetic phase to the paramagnetic phase at the Neel temperature value TN =159.31 K.
{"title":"Structural, electronic, and magnetic properties of ZnTe doped with transition metal Mn","authors":"Brach Brach, L. Bahmad, S. Benyoussef","doi":"10.31349/revmexfis.69.051004","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051004","url":null,"abstract":"In this article, we examine the structure, electronic, optical, and magnetic properties of ZnTe before and after doping with the transition metal Mn. The ab initio calculations of this compound were performed using the full potential linearized extended full potential planar waveform (FP-LAPW) in the context of density functional theory (DFT) implemented in the Wien2K code. The potential for exchange and correlation was addressed by the GGA approximation. The electronic properties show that the ZnTe material exhibits semiconductor behavior before doping and it becomes semimetal after doping. The findings attained by Monte Carlo simulations display that the ZnMnTe material goes from an antiferromagnetic phase to the paramagnetic phase at the Neel temperature value TN =159.31 K.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135049369","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 : 2023-09-01DOI: 10.31349/revmexfis.69.051601
Uriel Alberto Díaz-Reynoso, Ernesto Huipe-Domratcheva, Oracio Navarro
A new class of repulsive bound-electron pairs have been found in a Peierls lattice within the Hubbard model for energies E < 0 despite U > 0. These new repulsive bound-electron pairs have a high degree of localization as both the correlation energy U and the tS/tL hopping ratio increases. In order to study electronic correlation in Peierls lattices, our previous real space mapping method has also been extended to the so called generalized mapping method which is briefly presented here. In this paper, we concentrate our attention to discuss in detail the two-particle problem within a repulsive Hubbard model for the one-dimensional Peierls lattice.
{"title":"Repulsive bound-electron pairs in a Peierls lattice","authors":"Uriel Alberto Díaz-Reynoso, Ernesto Huipe-Domratcheva, Oracio Navarro","doi":"10.31349/revmexfis.69.051601","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051601","url":null,"abstract":"A new class of repulsive bound-electron pairs have been found in a Peierls lattice within the Hubbard model for energies E < 0 despite U > 0. These new repulsive bound-electron pairs have a high degree of localization as both the correlation energy U and the tS/tL hopping ratio increases. In order to study electronic correlation in Peierls lattices, our previous real space mapping method has also been extended to the so called generalized mapping method which is briefly presented here. In this paper, we concentrate our attention to discuss in detail the two-particle problem within a repulsive Hubbard model for the one-dimensional Peierls lattice.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42920209","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 : 2023-09-01DOI: 10.31349/revmexfis.69.051006
Y. Bouchentouf Idriss, B. Bouadjemi, M. Matougui, Mohammed Sid Ahmed Houari, T. Lantri, S. Haid, S. Bentata
In this paper, an exhaustive investigation was carried out on the compound double Perovskite Ba2GdReO6 including its structural, electronic, magnetic and thermoelectric properties. This study is based on the density functional theory (DFT) and more explicitly on the full potential linearized augmented plane wave (FP-LAPW), in the context of different approximations as exchange and correlation potential such as: The generalized gradient approximation (GGA) and its corollary the Becke – Johnson approach modified by Trans-Blaha (TB - mBJ) for a better approximation of the gap, and the GGA + U approach (where U is the Hubbard correction term). After an analysis of the results obtained, it turns out that the double perovskite material Ba2GdReO6 is a ferromagnetic material and has a half-metallic character, moreover, this compound has an integral magnetic moment of 9µB, which is in accordance with the rule of Slater-Pauling. From the study of the thermoelectric properties consisting in plotting curves of different parameters such as: the Seebeck coefficient (S), electrical conductivity per relaxation time (σ/τ), the electronic thermal conductivity per relaxation time ( /τ) and the merit factor (ZT) as a function of temperature, based on the GGA+U approximation, which is most suitable for the study of this compound, it emerges that the double pérovskite Ba2GdReO6 presents thermoelectric performances in medium to high temperature ranges, in view of the high values of the Seebeck coefficient and those of the electrical conductivity as well as a value close to unity for the merit factor, therefore, this compound can be used for thermoelectric applications in this range of temperatures (medium to high).
{"title":"Hubbard's parameter influence on Ba2GdReO6 properties, a promising ferromagnetic double Pérovskite oxide for thermoelectric applications","authors":"Y. Bouchentouf Idriss, B. Bouadjemi, M. Matougui, Mohammed Sid Ahmed Houari, T. Lantri, S. Haid, S. Bentata","doi":"10.31349/revmexfis.69.051006","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051006","url":null,"abstract":"In this paper, an exhaustive investigation was carried out on the compound double Perovskite Ba2GdReO6 including its structural, electronic, magnetic and thermoelectric properties. This study is based on the density functional theory (DFT) and more explicitly on the full potential linearized augmented plane wave (FP-LAPW), in the context of different approximations as exchange and correlation potential such as: The generalized gradient approximation (GGA) and its corollary the Becke – Johnson approach modified by Trans-Blaha (TB - mBJ) for a better approximation of the gap, and the GGA + U approach (where U is the Hubbard correction term). After an analysis of the results obtained, it turns out that the double perovskite material Ba2GdReO6 is a ferromagnetic material and has a half-metallic character, moreover, this compound has an integral magnetic moment of 9µB, which is in accordance with the rule of Slater-Pauling. From the study of the thermoelectric properties consisting in plotting curves of different parameters such as: the Seebeck coefficient (S), electrical conductivity per relaxation time (σ/τ), the electronic thermal conductivity per relaxation time ( /τ) and the merit factor (ZT) as a function of temperature, based on the GGA+U approximation, which is most suitable for the study of this compound, it emerges that the double pérovskite Ba2GdReO6 presents thermoelectric performances in medium to high temperature ranges, in view of the high values of the Seebeck coefficient and those of the electrical conductivity as well as a value close to unity for the merit factor, therefore, this compound can be used for thermoelectric applications in this range of temperatures (medium to high).","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43291190","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 : 2023-09-01DOI: 10.31349/revmexfis.69.050701
G. F. Torres del Castillo
We show that it is possible to define, e.g., the z-component of the linear momentum of the system formed by a charged particle and a magnetic field if and only if the magnetic field is invariant under translations along the z-axis. Similarly, it is possible to define the z-component of the angular momentum of the system formed by a charged particle and a magnetic field if and only if the magnetic field is invariant under rotations about the z-axis.
{"title":"The linear and the angular momentum stored in a distribution of charges in a magnetic field","authors":"G. F. Torres del Castillo","doi":"10.31349/revmexfis.69.050701","DOIUrl":"https://doi.org/10.31349/revmexfis.69.050701","url":null,"abstract":"We show that it is possible to define, e.g., the z-component of the linear momentum of the system formed by a charged particle and a magnetic field if and only if the magnetic field is invariant under translations along the z-axis. Similarly, it is possible to define the z-component of the angular momentum of the system formed by a charged particle and a magnetic field if and only if the magnetic field is invariant under rotations about the z-axis.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46265299","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 : 2023-09-01DOI: 10.31349/revmexfis.69.051005
F. Lekoui, Salim Hassani, E. Garoudja, Rachid El Amrani, W. Filali, Ouahid Sifi, S. Oussalah
Pure ZnO, Ag doped ZnO and Ag-Fe co-doped ZnOwere preparedusing thermal evaporation. XRD analysis confirms that all layers present a hexagonal wurtzite structure; however, there is a small shift in the peaks position due to thedistortion of the film’s lattice. Scanning Electron Microscopy (SEM) analysis reveals the morphological variation of the film’s surfaces due to the doping. Pure ZnO and Ag:ZnO films have a nanostructured surface, however, Ag-Fe:ZnO films showed a smooth surface without any nanoparticles. Raman analysis showed the presence of A1(LO), E2(high) andlocal vibrational modes (LVMs) for all layers. Ultraviolet–visible spectroscopy (UV-VIS) analysis shows that the films have a good transparency and the bandgapdecreases with ZnO doping from 3.80 eVto 3.78 eV and 3.70 eV,for pure ZnO, Ag:ZnO and Ag-Fe:ZnO films, respectively. The electrical properties confirm the semiconductor nature of ZnO films with a resistivity around 1.4 Ω.cm, and with Ag and Ag-Fe doping, the films behave like conductors with 1.4´10-4Ω.cm and 1.4´10-3Ω.cm, respectively. These results make the Ag:ZnO and Ag-Fe ZnO thin films good materials for photovoltaic application.
{"title":"Elaboration and characterization of pure ZnO, Ag:ZnO and Ag-Fe:ZnO thin films: Effect of Ag and Ag-Fe doping on ZnO physical properties","authors":"F. Lekoui, Salim Hassani, E. Garoudja, Rachid El Amrani, W. Filali, Ouahid Sifi, S. Oussalah","doi":"10.31349/revmexfis.69.051005","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051005","url":null,"abstract":"Pure ZnO, Ag doped ZnO and Ag-Fe co-doped ZnOwere preparedusing thermal evaporation. XRD analysis confirms that all layers present a hexagonal wurtzite structure; however, there is a small shift in the peaks position due to thedistortion of the film’s lattice. Scanning Electron Microscopy (SEM) analysis reveals the morphological variation of the film’s surfaces due to the doping. Pure ZnO and Ag:ZnO films have a nanostructured surface, however, Ag-Fe:ZnO films showed a smooth surface without any nanoparticles. Raman analysis showed the presence of A1(LO), E2(high) andlocal vibrational modes (LVMs) for all layers. Ultraviolet–visible spectroscopy (UV-VIS) analysis shows that the films have a good transparency and the bandgapdecreases with ZnO doping from 3.80 eVto 3.78 eV and 3.70 eV,for pure ZnO, Ag:ZnO and Ag-Fe:ZnO films, respectively. The electrical properties confirm the semiconductor nature of ZnO films with a resistivity around 1.4 Ω.cm, and with Ag and Ag-Fe doping, the films behave like conductors with 1.4´10-4Ω.cm and 1.4´10-3Ω.cm, respectively. These results make the Ag:ZnO and Ag-Fe ZnO thin films good materials for photovoltaic application.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48502463","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 : 2023-09-01DOI: 10.31349/revmexfis.69.050501
Abdelkader Bouazza, M. Khirat, M. Larbi, N. Bettahar, D. Rached
Topological insulators are novel quantum material states with insulating bulk band gaps and topologically protected metallic surface states that have been extensively studied owing to their intriguing properties for spintronic and quantum-computing applications. The structural, mechanical, electronic, thermal, and optical properties of inverse Heusler compounds La2RuPb and, Sc2 RuPb in two Hg2CuTi, Cu2 MnAltype structures were calculated using the full potential linear muffin-tin orbital simulation methodology as implemented in the computer code,which is based on density functional theory.We employed the local-density approximation for the exchange and correlation potential (XC) terms. Consequently, the optical characteristics of La2 RuPb, Sc2 RuPb and elastic constants Cij and their corresponding elastic moduli were computed for the first time. According to our structural calculations, La2 RuPb is more stable in its Hg2 CuTi-type structure than Sc2 RuPb in its Cu2 MnAl-type structure. However, the mechanical characteristics demonstrate their stability in the final stages of elastic deformation.
{"title":"Structural, mechanical, electronic, thermal, and optical properties of the inverse-Heusler compounds X2RuPb(X = La, Sc): A first-principles investigation","authors":"Abdelkader Bouazza, M. Khirat, M. Larbi, N. Bettahar, D. Rached","doi":"10.31349/revmexfis.69.050501","DOIUrl":"https://doi.org/10.31349/revmexfis.69.050501","url":null,"abstract":"Topological insulators are novel quantum material states with insulating bulk band gaps and topologically protected metallic surface states that have been extensively studied owing to their intriguing properties for spintronic and quantum-computing applications. The structural, mechanical, electronic, thermal, and optical properties of inverse Heusler compounds La2RuPb and, Sc2 RuPb in two Hg2CuTi, Cu2 MnAltype structures were calculated using the full potential linear muffin-tin orbital simulation methodology as implemented in the computer code,which is based on density functional theory.We employed the local-density approximation for the exchange and correlation potential (XC) terms. Consequently, the optical characteristics of La2 RuPb, Sc2 RuPb and elastic constants Cij and their corresponding elastic moduli were computed for the first time. According to our structural calculations, La2 RuPb is more stable in its Hg2 CuTi-type structure than Sc2 RuPb in its Cu2 MnAl-type structure. However, the mechanical characteristics demonstrate their stability in the final stages of elastic deformation.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44448951","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 : 2023-09-01DOI: 10.31349/revmexfis.69.051101
Lorena García-Iglesias, A. L. Rivera, R. Fossion
The extraction of circadian cycles from experimental data can be interpreted as a specific case of time-series or signal analysis, but chrono- biology and time-series analysis appear to have developed according to separate paths. Whereas some techniques such as continuous (CWT) and discrete wavelet analysis (DWT) are used frequently in rhythmobiology, other specialized methdos such as digital filters, nonlinear mode decomposition (NMD), singular spectrum analysis (SSA), empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD) and complete ensemble empirical model decomposition with adaptive noise (CEEMDAN) have only occasionally been applied. No studies are available that compare the applicability between a wide variety of different methods or for different variables, and this is the purpose of the present contribution. These methods improve the goodness-of-fit of the circadian cycle with respect to the standard approach of cosinor analysis. They have the additional advantage of being able to quantify the day-to-day variability of the circadian parameters of mesor, amplitude, period and acrophase around their average values, with potential clinical applications to distinguish between healthy and unhealthy populations. Finally, the circadian parameters are interpreted within the context of homeostatic regulation with distinctive statistics for regulated and effector variables.
{"title":"Circadian cycles: A time-series approach","authors":"Lorena García-Iglesias, A. L. Rivera, R. Fossion","doi":"10.31349/revmexfis.69.051101","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051101","url":null,"abstract":"\u0000 \u0000 \u0000The extraction of circadian cycles from experimental data can be interpreted as a specific case of time-series or signal analysis, but chrono- biology and time-series analysis appear to have developed according to separate paths. Whereas some techniques such as continuous (CWT) and discrete wavelet analysis (DWT) are used frequently in rhythmobiology, other specialized methdos such as digital filters, nonlinear mode decomposition (NMD), singular spectrum analysis (SSA), empirical mode decomposition (EMD), ensemble empirical mode decomposition (EEMD) and complete ensemble empirical model decomposition with adaptive noise (CEEMDAN) have only occasionally been applied. No studies are available that compare the applicability between a wide variety of different methods or for different variables, and this is the purpose of the present contribution. These methods improve the goodness-of-fit of the circadian cycle with respect to the standard approach of cosinor analysis. They have the additional advantage of being able to quantify the day-to-day variability of the circadian parameters of mesor, amplitude, period and acrophase around their average values, with potential clinical applications to distinguish between healthy and unhealthy populations. Finally, the circadian parameters are interpreted within the context of homeostatic regulation with distinctive statistics for regulated and effector variables. \u0000 \u0000 \u0000","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47976799","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 : 2023-09-01DOI: 10.31349/revmexfis.69.051001
Centli Tzentzangari Guerrero Caro, I. A. Figueroa, J. A. Verduzco, L. Pérez, L. Bejar, O. Hernández, I. Alfonso
The present work analyzes the sintering conditions for ∼ 3 mm inner diameter hollow iron spheres, sintered for manufacturing composite structures. Optimal sintering variables were investigated modifying temperature from 700 to 1200◦C, while times were between 1 and 3 h. Results showed that packing of the spheres increased with time and temperature: at 700◦C sintering was not enough; at temperatures from 800◦ to 1000◦C spheres were well sintered with porosity between them; while at higher temperatures were completely packed. Densities ranged from 0.6 gcm−3 to a maximum of 1.1 gcm−3 for spheres 100% packed, where it was observed a sphere-to-polyhedron shape transformation, with maximum values of penetration (0.39 mm) and sintering neck width (1.42 mm). Complete packing of the Fe particles of the sphere walls was also observed. The use of Design of Experiments made possible to establish correlations between sintering variables and characteristics such as neck width, penetration, porosity and packing. These results could be used as a starting point for the adequate selection of the sintering conditions of hollow Fe spheres for manufacturing hollow composite structures, taking into account not only the characteristics of the sintered hollow spheres but also of the Fe particles forming their walls.
{"title":"Solid state transformations from spheres to polyhedrons in hollow Fe spheres","authors":"Centli Tzentzangari Guerrero Caro, I. A. Figueroa, J. A. Verduzco, L. Pérez, L. Bejar, O. Hernández, I. Alfonso","doi":"10.31349/revmexfis.69.051001","DOIUrl":"https://doi.org/10.31349/revmexfis.69.051001","url":null,"abstract":"The present work analyzes the sintering conditions for ∼ 3 mm inner diameter hollow iron spheres, sintered for manufacturing composite structures. Optimal sintering variables were investigated modifying temperature from 700 to 1200◦C, while times were between 1 and 3 h. Results showed that packing of the spheres increased with time and temperature: at 700◦C sintering was not enough; at temperatures from 800◦ to 1000◦C spheres were well sintered with porosity between them; while at higher temperatures were completely packed. Densities ranged from 0.6 gcm−3 to a maximum of 1.1 gcm−3 for spheres 100% packed, where it was observed a sphere-to-polyhedron shape transformation, with maximum values of penetration (0.39 mm) and sintering neck width (1.42 mm). Complete packing of the Fe particles of the sphere walls was also observed. The use of Design of Experiments made possible to establish correlations between sintering variables and characteristics such as neck width, penetration, porosity and packing. These results could be used as a starting point for the adequate selection of the sintering conditions of hollow Fe spheres for manufacturing hollow composite structures, taking into account not only the characteristics of the sintered hollow spheres but also of the Fe particles forming their walls.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49388149","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 : 2023-09-01DOI: 10.31349/revmexfis.69.050703
J. A. Cázares, Valeriy Dvoeglazov
We present explicit examples of generalizations in relativistic quantum mechanics. First of all, we discuss the generalized spin-1/2 equations for neutrinos. They have been obtained by means of the Gersten-Sakurai method for derivations of arbitrary-spin relativistic equations. Possible physical consequences are discussed. Next, it is easy to check that both Dirac algebraic equations Det(ˆp − m) = 0 and Det(ˆp + m) = 0 for u− and v− 4-spinors have solutions with p0 = ±Ep = ± p p2 + m2. The same is true for higher-spin equations. Meanwhile, every book considers the equality p0 = Ep for both u− and v− spinors of the (1/2, 0) ⊕ (0, 1/2) representation, thus applying the DiracFeynman-Stueckelberg procedure for elimination of the negative-energy solutions. The recent Ziino works (and, independently, the articles of several others) show that the Fock space can be doubled. We re-consider this possibility on the quantum field level for both S = 1/2 and higher spin particles. The third example is: we postulate the non-commutativity of 4-momenta, and we derive the mass splitting in the Dirac equation. The applications are discussed.
{"title":"Generalized equations and their solutions in the (1/2,0)+(0,1/2) representations of the Lorentz group","authors":"J. A. Cázares, Valeriy Dvoeglazov","doi":"10.31349/revmexfis.69.050703","DOIUrl":"https://doi.org/10.31349/revmexfis.69.050703","url":null,"abstract":"We present explicit examples of generalizations in relativistic quantum mechanics. First of all, we discuss the generalized spin-1/2 equations for neutrinos. They have been obtained by means of the Gersten-Sakurai method for derivations of arbitrary-spin relativistic equations. Possible physical consequences are discussed. Next, it is easy to check that both Dirac algebraic equations Det(ˆp − m) = 0 and Det(ˆp + m) = 0 for u− and v− 4-spinors have solutions with p0 = ±Ep = ± p p2 + m2. The same is true for higher-spin equations. Meanwhile, every book considers the equality p0 = Ep for both u− and v− spinors of the (1/2, 0) ⊕ (0, 1/2) representation, thus applying the DiracFeynman-Stueckelberg procedure for elimination of the negative-energy solutions. The recent Ziino works (and, independently, the articles of several others) show that the Fock space can be doubled. We re-consider this possibility on the quantum field level for both S = 1/2 and higher spin particles. The third example is: we postulate the non-commutativity of 4-momenta, and we derive the mass splitting in the Dirac equation. The applications are discussed.","PeriodicalId":21538,"journal":{"name":"Revista Mexicana De Fisica","volume":null,"pages":null},"PeriodicalIF":1.7,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"69297335","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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