Brazilian Journal of Physics最新文献

{"title":"Influence of Cobalt on Structural, Morphological, Dielectric, and Magnetic Properties of Barium M-Type Hexagonal Ferrites for Technological Applications","authors":"Muhammad Zahid, Hasan M. Khan, Zunaira Munawar, Shehla Honey, Muhammad A. Assiri, Muhammad Arif Khan, Zia Ur Rehman","doi":"10.1007/s13538-025-01698-w","DOIUrl":"10.1007/s13538-025-01698-w","url":null,"abstract":"<div><p>Hexagonal ferrites have gained considerable attention due to their promising applications in electronic fields. Herein, the synthesis of M-type hexaferrites with nominal composition Ba<sub>1-x</sub>Co<sub>x</sub>Fe<sub>12</sub>O<sub>19</sub> at x = (0.0, 0.2, 0.4, 0.6) was successfully prepared by the facile and cost-effective sol–gel auto-combustion technique. The synthesized samples were characterized by a variety of techniques, and dielectric properties were investigated by impedance analyzer. Structural, morphological, magnetic, and dielectric characteristics of the synthesized samples were explored. The objectives of the present study are to enhance the magnetic and dielectric characteristics that were obtained by the variation of cobalt. X-ray diffraction analysis was applied to verify the single-phase hexagonal ferrites. Physical properties such as bulk density, X-ray density, and porosity of the Ba<sub>1-x</sub>Co<sub>x</sub>Fe<sub>12</sub>O<sub>19</sub> at x = (0.0, 0.2, 0.4, 0.6) M-type hexagonal ferrites were calculated. As a result of internal stress induced by the alteration in ionic radii of the dopant ion (Co<sup>2+</sup> with ionic radii 0.72 Å) and base element (Ba<sup>2+</sup> with ionic radii 1.49 Å), lattice parameters were decreased. The prepared materials were analyzed using scanning electron microscopy (SEM), which showed the hexagonal platelet structure. The dielectric constant gradually increased with the increase of dopant concentration. It is found that these characteristics are beneficial for high-frequency technologies such as phase shifters and modulators, as well as magnetic recording media. The saturation magnetization was found to be in the range of 58.27–64.26 (emu/g), and coercivity was found to be from 208.95–568.46 Oe. The dielectric and magnetic properties of Ba<sub>1-x</sub>Co<sub>x</sub>Fe<sub>12</sub>O<sub>19</sub> at x = (0.0, 0.2, 0.4, 0.6) M-type hexagonal ferrites with the cobalt variation suggested that the prepared materials are excellent candidates for modern gadgets.</p><h3>Graphical Abstract</h3><p>X-ray diffraction pattern of the cobalt-substituted M-type hexaferrites with composition Ba<sub>1-x</sub>Co<sub>x</sub>Fe<sub>12</sub>O<sub>19</sub> x = (0.0, 0.2, 0.4, 0.6) is shown in the figure. The pattern of the synthesized nanoparticles exhibits a single-phase homogeneous structure. It is found that each sample had no impurity phase and was hexagonally crystallized to the P63/mmc space group. All the peaks matched with the JCPDS card number (43–0002). The prepared samples exhibited well-matched intensity peaks with the miller indices of the peaks (006), (110), (008), (114), (205), (206), (1011), (209), (2010), (218), (0014), and (0016) in the diffraction planes. The cell software determined the lattice parameters (a and c). Lattice parameter “a” was found to be in the range of (5.888–5.857) Å and “c” was found to be in the range of (23.152–23.119) Å. Crystallite size ranges from 39.08 to 4","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994610","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}

{"title":"Phase Shifts Due to Head-on Collision of Electron Acoustic Waves and Production of Rogue Waves: Kappa-Deformed Kaniadakis Electrons","authors":"Umma Imon,&nbsp;M. S. Bhuyan,&nbsp;M. S. Alam","doi":"10.1007/s13538-025-01700-5","DOIUrl":"10.1007/s13538-025-01700-5","url":null,"abstract":"<div><p>The effects of electron-acoustic (EA) waves’ head-on collisions and rogue wave (RW) production are studied in a collisionless, unmagnetized plasma composed of stationary ions, deformed Kaniadakis-distributed hot electrons, and cold fluid electrons. The nonlinear Schrödinger equation is generated using the standard reductive perturbation (SRP) approach, and the Korteweg-de Vries (KdV) equations (KdVEs) and modified KdVEs (mKdVEs) are determined via the general case using the extended Poincaré-Lighthill-Kuo (ePLK) perturbation method (ePLKM). In particular, the influence of the density ratio and the deformed Kaniadakis parameter on the RW structure, the creation of EA soliton structures, and phase shifts resulting from head-on collisions are examined. The construction of EA solitons, the generation of RW, and the variations of phase shifts are found to be significantly influenced by the parameters in question. In this work, the collisions of KdV solitons show positive and negative phase shifts. Though both the positive and negative phase shifts result from the interaction of mKdV solitons and the influence of the relevant parameters, only the positive phase shifts are studied here.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994678","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}

{"title":"Blazars Jets and Prospects for TeV-PeV Neutrinos and Gamma Rays Through Cosmic-Ray Interactions","authors":"Rodrigo Sasse,&nbsp;Rubens Jr. Costa,&nbsp;Luiz A. Stuani Pereira,&nbsp;Rita C. dos Anjos","doi":"10.1007/s13538-024-01689-3","DOIUrl":"10.1007/s13538-024-01689-3","url":null,"abstract":"<div><p>This study explores the origins of cosmic rays and their secondary messengers, focusing on the potential role of four BL Lacs—W Comae, 1ES 1959+650, PKS 2005-489, and PKS 2155-304—as potential sources of astrophysical neutrinos and gamma rays. We analyzed a single-zone model to understand the interactions between high-energy protons and ambient photons within blazar jets, leading to neutrino production observables and gamma-ray emission. This modeling contextualizes the emissions within multiwavelength observations and evaluates the capabilities of the next-generation Cherenkov Telescope Array Observatory (CTAO) in detecting these emissions. Our estimations suggest that these sources could be effective emitters of CRs, highlighting the need for future multimessenger observations to further investigate and constrain this class of sources.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142994548","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}

{"title":"Annealed Mean-Field Epidemiological Model on Scale-Free Networks with a Mitigating Factor","authors":"K. M. Kim,&nbsp;M. O. Hase","doi":"10.1007/s13538-025-01696-y","DOIUrl":"10.1007/s13538-025-01696-y","url":null,"abstract":"<div><p>An annealed version of the quenched mean-field model for epidemic spread is introduced and investigated analytically and assisted by numerical calculations. The interaction between individuals follows a prescription that is used to generate a scale-free network, and we have adjusted the number of connections to produce a sparse network. Specifically, the model’s behavior near the infection threshold is examined, as well as the behavior of the stationary prevalence and the probability that a connection between individuals encounters an infected one. We found that these functions display a monotonically increasing dependence on the infection rate. Subsequently, a modification that mimics the mitigation in the probability of encountering an infected individual is introduced, following an old idea rooted in the Malthus-Verhulst model. We found that this modification drastically changes the probability that a connection meets an infected individual. However, despite this change, it does not alter the monotonically increasing behavior of the stationary prevalence.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142963041","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}

{"title":"Enhanced Linear, Nonlinear Optical, and Modulus Dielectric Properties of Fluorescein Sodium Salt Dye Embedded Within Epoxy Resin Composite Materials for Renewable Energy Applications","authors":"Abdelfatteh Bouzidi,&nbsp;Soumaya Gouadria,&nbsp;Batool Bader Alyahya,&nbsp;Fatemah F. Al-Harbi","doi":"10.1007/s13538-024-01691-9","DOIUrl":"10.1007/s13538-024-01691-9","url":null,"abstract":"<div><p>This research is aimed at investigating the potential of using fluorescent dyes, specifically fluorescein sodium salt dye (FSSD), embedded within epoxy resin (EP) as a material for luminescent solar concentrators (LSCs). LSCs are devices that capture and concentrate sunlight onto a smaller area, increasing the efficiency of solar cells. The study revealed a relationship between FSSD at different concentrations and EP molecules. The FSSD might be well-dispersed on a molecular level within the EP matrix. This homogeneous distribution is supported by the lack of distinct peaks in the XRD pattern, indicating the absence of any ordered crystal structure of FSSD within the composite. FSSD significantly influences the optical properties of the EP. It reduces light transmittance while increasing absorbance at specific wavelengths, which is crucial for efficient light capture in LSCs. The high polarizability of FSSD molecules and their random orientation can give rise to nonlinear optical phenomena. The enhanced light sensitivity of the FSSD@EP composite materials affects its nonlinear optical properties. These nonlinearities describe how the material’s response to light changes with increasing light intensity. The peak observed suggests a frequency range (10⁵–10⁷ rad/s) where this energy dissipation is most prominent. This points towards a relaxation process occurring within the material at those frequencies. As the frequency of the electric field increases, both the real part (M′) and the imaginary part (M″) of the complex modulus (M*) are expected to change in the FSSD@EP composite materials.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142941145","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}

{"title":"Structural, Magnetic, and Dielectric Properties of Bi1-xCoxFeO3 Nanoparticles for Photocatalytic Application","authors":"Ranjith Anburaja,&nbsp;Shaik Kaleemulla","doi":"10.1007/s13538-024-01676-8","DOIUrl":"10.1007/s13538-024-01676-8","url":null,"abstract":"<div><p>Cobalt-doped bismuth ferrite (Bi_1-xCo_xFeO₃) nanoparticles (NPs) at <i>x</i> = 0.00, 0.03, 0.07 were synthesized using the sol–gel auto-combustion method and studied the influence of cobalt (Co) on structural, surface, chemical, optical, magnetic, and photocatalytic properties on Bi_1-xCo_xFeO₃ nanoparticles. X-ray diffraction (XRD) studies revealed the rhombohedral structure of the synthesized nanoparticles with a mean crystallite size of 51 nm. Using Tauc’s relation, the optical band gap was calculated, and it decreased from 2.13 to 1.6 eV with increased Co concentration. The iron-oxygen (Fe–O) stretching vibrations were confirmed from Fourier transform infrared (FT-IR) spectra. Magnetic properties of the nanoparticles were studied using a vibrating sample magnetometer and found that Bi_1-xCo_xFeO₃ nanoparticles are ferromagnetic at room temperature. The strength of magnetization increased with an increase of Co doping concentration. Photocatalytic properties of the Bi_1-xCo_xFeO₃ nanoparticles were studied using a UV–Vis-NIR spectrophotometer, and it was found that Bi_1-xCo_xFeO₃ nanoparticles can be used as a photocatalyst in the visible region of the spectrum. Methyl blue (MB) dye was used to study the dye degradation property of pure and Co-doped BiFeO₃ nanoparticles, and the results were explained in detail. The Bi_1-xCo_xFeO₃ nanoparticles at <i>x</i> = 0.07 exhibited the highest photocatalytic activity (97.9%).</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938910","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}

{"title":"Computing the Wall Erosion Rate of a Low-Power Hall Thruster Using Particle-in-Cell Numerical Simulations","authors":"Rodrigo A. Miranda,&nbsp;Leonardo L. Braga,&nbsp;Rodrigo A. F. Alves,&nbsp;Alexandre A. Martins,&nbsp;José L. Ferreira,&nbsp;Lui Habl","doi":"10.1007/s13538-024-01692-8","DOIUrl":"10.1007/s13538-024-01692-8","url":null,"abstract":"<div><p>We present a numerical study of the erosion of channel walls applied to the PHALL Hall thruster being developed at the Plasma Physics Laboratory at the University of Brasilia. The simplified two-dimensional model retains the axial and radial directions to evaluate the erosion rate due to energetic ions. Plasma particles and fields are solved using the particle-in-cell and Monte Carlo collision techniques. The electrostatic potential and ion density profiles are obtained after the simulation reaches the steady state. We compute the channel wall erosion rate from the time series of the number of sputtered particles. We also perform and analyze a simulation of an SPT-100 Hall thruster. Our results show that the erosion acts mainly near the middle of the channel walls of the PHALL thruster, in agreement with patterns of wall material degradation observed in the laboratory device after experimental tests. The implications of the erosion pattern predicted for the PHALL thruster are discussed.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938689","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}

{"title":"Oxidative Stress and Lipid Profile During Acute Phase of COVID-19 Infection and After Recovery: Evidence of a Sequel in LDL","authors":"Zahra Lotfollahi,&nbsp;Luana dos S. Neres,&nbsp;Andressa F. Mathias,&nbsp;Maria C. P. de Freitas,&nbsp;Flávia de C. Cartolano,&nbsp;Ana C. Varella,&nbsp;Paulo A. Lotufo,&nbsp;Alessandra C. Goulart,&nbsp;Nágila R. T. Damasceno,&nbsp;Juliana B. de Andrade,&nbsp;Ricardo A. Fock,&nbsp;Antonio M. Figueiredo Neto","doi":"10.1007/s13538-024-01687-5","DOIUrl":"10.1007/s13538-024-01687-5","url":null,"abstract":"<div><p>This study aimed to investigate the atherogenicity (quality) of LDL particles in patients with acute and recovered from COVID-19 infection. The participants were adults, aged 18 years or older of both sexes. Those with positive RT-PCR results at baseline were included in the Acute COVID-19 group (n = 33), and those with negative RT-PCR six months after acute infection, were included in the Recovered COVID-19 group (n = 30). The LDL quality was evaluated using three validated methods: Z-scan, UV–visible spectroscopy, and Lipoprint system. The Recovered COVID-19 group showed significantly higher numbers of large LDL particles (less atherogenic) than the Acute COVID-19 group (P &lt; 0.05). We also found that COVID-19 infection was associated with the oxidative modification of LDL particles. D-dimer and CRP levels were correlated with Z-scan results and antioxidant-amount estimate. Moreover, we noticed that the infection left a sequel in LDL quality, even after six months of recovery. These findings highlight the importance of monitoring lipids during and after recovery from COVID-19 infection, and their potential deleterious effect on the LDL profile might correlate with the progression of atherosclerosis and poor clinical outcomes.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938947","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}

{"title":"Investigation of Structural, Morphological, and Photoluminescence Properties of Nanocrystalline Copper doped Tin Oxide Thin Films Grown by RF Sputtering Method","authors":"Shima Khosravani,&nbsp;Fatemeh Hajakbari,&nbsp;Alireza Hojabri","doi":"10.1007/s13538-024-01690-w","DOIUrl":"10.1007/s13538-024-01690-w","url":null,"abstract":"<div><p>This research investigates the structural, morphological, and optical properties of SnO₂ and Cu-doped SnO₂ films deposited on glass and FTO substrates using the RF sputtering technique. The Cu-doped samples were subsequently annealed in an oxygen flow at temperatures of 400 and 500 °C. X-ray diffraction (XRD) analysis revealed that pure SnO₂ thin films exhibited an amorphous structure on both substrates. In contrast, the Cu-doped SnO₂ sample on the glass substrate maintained its amorphous state, while the sample on the FTO substrate transitioned to a tetragonal rutile structure. Thermal annealing further induced a transformation to a tetragonal rutile structure for samples on both substrates. Energy dispersive spectroscopy (EDS) confirmed the incorporation of Cu into the SnO₂ films. The estimated crystallite sizes ranged from 16 to 20 nm for the glass substrate and from 20 to 31 nm for the FTO substrate. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) analyses demonstrated uniform surface morphology with a smooth texture and strong adhesion to the substrates. The band gap energy (Eg) values for the unannealed samples were found to be 3.52, 3.40, 3.50, and 3.29 eV. Notably, Cu doping and the deposition of SnO₂ films on FTO substrates resulted in a reduction of the band gap. These findings provide valuable insights into the effects of Cu doping, annealing, and substrate type on the structural and optical properties of SnO₂, paving the way for advanced optoelectronic applications.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938946","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}

{"title":"Fundamental Properties of Dust Ion-Acoustic and Rogue Wave Analysis in Relativistic Dusty Plasmas","authors":"Muhammad Shahnewaz Bhuyan,&nbsp;Umma Imon,&nbsp;Mohammad Shah Alam","doi":"10.1007/s13538-024-01672-y","DOIUrl":"10.1007/s13538-024-01672-y","url":null,"abstract":"<div><p>The collisionless, unmagnetized relativistic dusty plasma system comprising relativistic positively charged ions, energetic ion beams, and Maxwellian electrons is considered to study the fundamental properties of dust ion-acoustic waves (DIAWs) and formation of rogue waves (RWs). The Korteweg-de Vries (KdV) equation and nonlinear Schrödinger equation (NLSE) are derived using the well-known reductive perturbation and derivative expansion approaches, respectively. The concerned parameters play a crucial role in the fundamental properties (such as phase velocity, nonlinearity, dispersion, production, and propagation) of DIAWs. In addition, the rational solution of rogue waves (RWs) exists due to the effect of concerned parameters except the ion beam for argon.</p></div>","PeriodicalId":499,"journal":{"name":"Brazilian Journal of Physics","volume":"55 2","pages":""},"PeriodicalIF":1.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938944","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}