Indian Journal of Physics最新文献

{"title":"Role of viscous fluid in FLRW model with observational constraints","authors":"Anirudh Pradhan,&nbsp;G. K. Goswami","doi":"10.1007/s12648-026-04115-3","DOIUrl":"10.1007/s12648-026-04115-3","url":null,"abstract":"<div><p>In this study, we investigate the role of bulk viscosity in the evolution of a spatially flat Friedmann-Lemaître-Robertson-Walker (FLRW) universe dominated by dust. By parameterizing the bulk viscosity as <span>(tilde{p}= -3(l + m (H'(t) + H^2) + n H^2) H)</span>, we derived the modified Einstein field equations and reformulate them in terms of the redshift z. Using the Hubble datasets with 46 data points and Pantheon+ compilation with 1701 supernova measurements, we estimated the model parameters (<span>(H_0)</span>, l, m, n) through <span>(chi ^{2})</span> minimization and refined them using Markov chain Monte Carlo (MCMC) simulations. Our analysis reveals a transition redshift <span>(z_t = 0.585)</span>, marking the universe’s shift from decelerated to accelerated expansion, and a current deceleration parameter <span>(q_0 =- 0.705)</span> consistent with the <span>(Lambda)</span>CDM model. The current age of the universe obtained from our model was <span>(t_{0})</span> = 14.5734 Gyrs. Additionally, we estimate the present Hubble constant, <span>(H_0)</span>, to be 68 km/s/Mpc based on the Hubble datasets and approximately 73 km/s/Mpc using the Pantheon+ datasets. The best-fit cosmological parameters indicate a recent transition to accelerated expansion at <span>(z_{t} approx 0.55)</span>, a present-day deceleration parameter <span>(q_{0} approx -0.55)</span>, a Hubble constant in the range <span>(67; to- 74 kms^{-1} Mpc^{-1})</span>, and a cosmic age <span>(t_{0} approx 13.7)</span> Gyr, consistent with current observational constraints. This disparity highlights the ongoing Hubble tension-a discrepancy between locally measured values of <span>(H_0)</span> (e.g., via supernovae) and values inferred from the early universe (e.g., CMB observations). Our findings are consistent with the larger trend of greater <span>(H_0)</span> values from late-universe observations compared with early-universe predictions, highlighting the need for more research into the underlying physical or systematic sources of this tension. We further evaluate the evolution of the cosmological parameters, including the equation of state parameter <span>(omega (z))</span>, energy density <span>(rho (z))</span> and pressure <i>p</i>(<i>z</i>). Statefinder diagnostics (<i>r</i>, <i>s</i>) demonstrate the versatility of the model, capturing its deviation from and convergence toward <span>(Lambda)</span>CDM at specific epochs. This study emphasizes the importance of bulk viscosity in explaining the universe’s accelerated expansion and provides a strong framework for assessing various cosmological theories.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 10","pages":"4285 - 4301"},"PeriodicalIF":1.7,"publicationDate":"2026-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148909684","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":"Structure-dependent glass-forming ability and relaxation dynamics in amorphous acetohexamide, piroxicam, and 5-fluorouracil: a thermal and dielectric investigation","authors":"K. Rasheed,&nbsp;Aboothahir Afzal,&nbsp;M. Shahin Thayyil,&nbsp;K Jalaja,&nbsp;M. P. Nighilnath,&nbsp;Ahmed Saleh Yaseen,&nbsp;M. Saifunnisa","doi":"10.1007/s12648-026-04111-7","DOIUrl":"10.1007/s12648-026-04111-7","url":null,"abstract":"<div><p>This study investigates the glass-forming ability (GFA), thermal stability, and molecular relaxation dynamics of amorphous forms of three model pharmaceuticals—acetohexamide, piroxicam, and 5-fluorouracil—using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and broadband dielectric spectroscopy (BDS). Crystalline samples were heated above their respective melting points (T_m) and melt-quenched to induce vitrification. TGA confirmed thermal processing windows sufficient to prevent degradation during quenching. DSC measurements yielded glass transition temperatures (T_g) of 323–331 K for acetohexamide and 323 K for piroxicam; however, a clear glass transition could not be resolved for 5-Fluorouracil due to its intense recrystallization tendency. Piroxicam exhibited superior GFA with no crystallization during cooling, whereas Acetohexamide and 5-Fluorouracil showed rapid recrystallization upon heating. BDS analysis, evaluated via permittivity and electric modulus formalisms, revealed primary α-relaxations associated with the glass transition alongside secondary γ-relaxations in piroxicam. In contrast, prominent ionic conductivity masked the structural α-process in acetohexamide and 5-fluorouracil, leaving only secondary relaxations detectable in acetohexamide. These findings demonstrate a clear correlation between molecular architecture (planarity, hydrogen-bonding capacity, and conformational flexibility) and amorphous state stability. The results highlight piroxicam’s intrinsic robustness for solubility enhancement, while underscoring the necessity of crystallization inhibitors for acetohexamide and 5-fluorouracil formulations. Ultimately, this integrated thermal and dielectric approach provides critical insights into glass transition dynamics, supporting predictive strategies for stable amorphous pharmaceutical development.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4669 - 4685"},"PeriodicalIF":1.7,"publicationDate":"2026-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163134","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":"A conceptual link to long-wave and tsunami-like events using neural networks","authors":"N. Hemnath,&nbsp;Sandip Saha,&nbsp;Santanu Raut","doi":"10.1007/s12648-026-04116-2","DOIUrl":"10.1007/s12648-026-04116-2","url":null,"abstract":"<div><p>A partial differential equation (PDE)-based approach combines soliton theory with data-driven and physics-constrained training to probe solitary wave dynamics and shoaling-induced amplification. A comparison of two advanced deep learning approaches, fully connected neural networks (FCNs) and physics-informed neural networks (PINNs), demonstrates distinct trade-offs among predictive accuracy, computational efficiency, and physical consistency. By explicitly incorporating governing physical laws into the training process, Such PINNs impose governing physical constraints that markedly improve extrapolation at significantly higher cost, where FCNs have superior accuracy and computational efficiency. These findings provide practical criteria for selecting appropriate deep learning strategies for complex wave modeling applications. From a geophysical perspective, the <i>variable-coefficient KdV equation</i> is employed as an idealized surrogate to expose bathymetry-driven shoaling and nonlinear energy focusing in tsunami-like wave evolution. The results further reinforce the established physical understanding that variations in bathymetric amplitude and abrupt topographic changes strongly influence wave generation, propagation, and amplification in deep-ocean environments. Overall, the findings position physics-aware deep learning as a decisive and scalable paradigm for physically grounded environmental wave analysis and predictive modeling.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4847 - 4870"},"PeriodicalIF":1.7,"publicationDate":"2026-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163128","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":"New Rattling Heuslers Ba2YO (Y = Ni, Pd, Pt) for solar-cell applications, ab-initio investigation of optoelectronic and thermoelectric properties","authors":"K. Mechehoud,&nbsp;M. Mana,&nbsp;M. R. Ghezzar,&nbsp;F. Bendahma,&nbsp;R. Baghdad,&nbsp;N. Benderdouche","doi":"10.1007/s12648-026-04057-w","DOIUrl":"10.1007/s12648-026-04057-w","url":null,"abstract":"<div><p>In this work, density functional theory (DFT) calculations were performed using the generalized gradient approximation (GGA) and the Tran–Blaha modified Becke–Johnson (TB-mBJ) potential to study the structural, electronic, and thermoelectric properties of Rattling Heusler compounds Ba₂YO (Y = Ni, Pd, Pt). It was found that the cubic Fm-3m space group of these compounds was energetically more favorable in the non-magnetic phase. The calculated equilibrium lattice parameters agree well with previously published theoretical and experimental data. The results revealed that these three compounds are semiconductors with a band gap ranging from 0.62 to 1.75 eV, making them ideal for photovoltaic applications. Furthermore, they exhibit strong optical absorption (α) in the visible and ultraviolet spectra. With a thermoelectric figure of merit (ZT) close to 1, Ba₂YO (Y = Ni, Pd, Pt) compounds emerge as promising candidates for high-efficiency thermoelectric devices.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 9","pages":"3687 - 3696"},"PeriodicalIF":1.7,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148750641","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":"MXene-based hybrid plasmonic waveguides with strong field confinement and low crosstalk","authors":"Jie Jia,&nbsp;Ruiqing Xue,&nbsp;Jiaxin Zhang,&nbsp;Da Teng","doi":"10.1007/s12648-026-04113-5","DOIUrl":"10.1007/s12648-026-04113-5","url":null,"abstract":"<div><p>MXene exhibits unique plasmonic properties in the near-infrared region, which have garnered significant research interest. However, MXene plasmons typically suffer from weak field confinement and high losses. The present work proposes a hybrid plasmonic waveguide consisting of a silica layer inserted between the MXene film and a Si strip waveguide. By analyzing the thickness-dependent dielectric properties of MXene, a thickness of 10 nm is identified as optimal choice owing to its superior material quality factor. With finite element analysis, the modal characteristics are systematically investigated at the wavelength of 1550 nm. The results demonstrate that the plasmon mode in proposed waveguide exhibits strong modal field confinement, with a minimum modal area of 1.335 × 10⁻⁴<i>A</i>₀ (where <i>A</i>₀ = <i>λ</i>²<i>/</i>4), and achieves a stable figure of merit. Compared with a 75-nm-thick MXene layer, the 10-nm-thick layer enables smaller integration spacing and lower crosstalk in coupled systems. These findings may contribute to the design of high-performance MXene photonic devices with reduced crosstalk.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4947 - 4954"},"PeriodicalIF":1.7,"publicationDate":"2026-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163158","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":"One-dimensional quantum droplets in curved space","authors":"Abdelhakim Benkrane","doi":"10.1007/s12648-026-04102-8","DOIUrl":"10.1007/s12648-026-04102-8","url":null,"abstract":"<div><p>In this paper, we study quantum droplets in one dimension (1D) under the influence of space curvature by redefining the momentum operator <span>(hat{P}=-i(1+alpha x^{2})partial /partial x)</span>, resulting in a maximum length and a minimum momentum, consistent with anti-de Sitter space (AdS). By analyzing this effect through the <span>(alpha)</span> parameter on the exact solution of free quantum droplets, we find that the relationship between the number of atoms and the chemical potential deviates from the ordinary case. Additionally, we observe that the characteristic flat-top shape of quantum droplets can disappear, transforming into a Gaussian profile in the presence of the maximum length (minimum momentum). Furthermore, our findings reveal that the interaction of quantum droplets with space curvature results in an increase in their size. Finally, by studying this effect on the variational solution using a Gaussian ansatz for small droplets, we conclude that <span>(alpha)</span> reduces the stability and self-localization of the quantum droplets.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4813 - 4822"},"PeriodicalIF":1.7,"publicationDate":"2026-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163058","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":"Synthesis of erbium doped cadmium oxide thin films and investigation of their optoelectronic properties: by sol–gel spin coating method","authors":"Seema Gupta,&nbsp;Rajesh Lalwani,&nbsp;Mukul Gupta,&nbsp;Prashant Kumar Sahu","doi":"10.1007/s12648-026-04109-1","DOIUrl":"10.1007/s12648-026-04109-1","url":null,"abstract":"<div><p>In this study, synthesis of erbium-doped and undoped cadmium oxide (CEr) thin films on glass substrates using the sol–gel spin coating method, a low-cost and scalable fabrication technique. The crystalline quality of the films with preferential orientation along the (111) plane is confirmed by structural analysis employing X-ray diffraction. A cauliflower-like surface structure with roughness varying from 112.10 to 156.81 nm is shown by morphological investigations utilizing atomic force and scanning electron microscopy. This surface structure is crucial for light interaction in optoelectronic applications. The presence of distinctive chemical bonds in the films is verified by Fourier transform infrared spectroscopy. Good crystallinity is indicated by Raman analysis, which reveals peaks at 293.5 and 402.6 cm^-1 that correspond to longitudinal optical phonon modes. The potential of these films for blue light-emitting applications is shown by photoluminescence analysis, which shows a strong blue emission peak centred at 416 nm. Transmittance increases with Er doping, which is beneficial for transparent electrode applications. Based on optical studies, the optical band gap decreases with increasing dopant concentration, suggesting a change in the band structure. All things considered, these results show that Er-doped CdO thin films are viable options for next-generation optoelectronic applications, especially in transparent electronics and possible blue light-emitting devices.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4925 - 4946"},"PeriodicalIF":1.7,"publicationDate":"2026-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163157","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":"Thermo-mechanical stability and strong optical absorption in quaternary chalcogenides ACdCu3Se4 (A = Sc, Y): a first-principles study","authors":"Ahmed Azzouz-Rached,&nbsp;Amir Ullah,&nbsp;Mubashir Hussain,&nbsp;Eman M. Alshehri,&nbsp;Vineet Tirth,&nbsp;Ali Algahtani,&nbsp;Saleha Qissi,&nbsp;Wafa S. Aljuaid,&nbsp;Essam A. Al-Ammar,&nbsp;Nasir Rahman,&nbsp;Mudasser Husain","doi":"10.1007/s12648-026-04092-7","DOIUrl":"10.1007/s12648-026-04092-7","url":null,"abstract":"<div><p>Using density functional theory, we present a first-principles study of quaternary chalcogenides ACdCu₂Se₄ (A = Sc, Y). Negative formation energies (− 1.231 eV/atom for Sc and − 1.365 eV/atom for Y) confirms thermodynamic stability. Structural optimization within GGA-PBE and a parabolic equation of state indicate structural stability. Elastic constants satisfy the Born criteria, with Pugh’s ratios (0.61 for Sc and 0.65 for Y) and negative Cauchy pressures indicating brittle, covalent behavior. While PBE predicts metallicity, the mBJ approach reveals both compounds as indirect semiconductors, with Cu-3<i>d</i>/Se-4<i>p</i> states dominating the valence band and Cd-s and Sc(Y)-d states contributing to the conduction band. Strong optical absorption (~ 9 × 10⁵ cm⁻¹) in the UV range is observed near 2.5–3.0 eV. Phonon dispersion shows no imaginary modes, confirming dynamical stability. Debye temperatures of 318.96 K (Sc) and 308.15 K (Y), sound velocities around 4600–4730 m/s, and melting temperatures near 1040 K indicate stable thermal behavior. Overall, the mechanical, electronic, optical, and thermal properties confirm phase stability, highlighting ACdCu₂Se₄ (A = Sc, Y) as promising materials for optoelectronic, thermoelectric, and photovoltaic applications.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4553 - 4571"},"PeriodicalIF":1.7,"publicationDate":"2026-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163096","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":"Computational study of structural stability and electronic properties of the ternary half-Heusler LiVN","authors":"Mustafa M. Jaafar,&nbsp;Mudhahir H. Jolan,&nbsp;Nihaya Hadi Abdulwahhab,&nbsp;Mostafa A. Algrifi","doi":"10.1007/s12648-026-04095-4","DOIUrl":"10.1007/s12648-026-04095-4","url":null,"abstract":"<div><p>This first-principles investigation confirms that the LiVN half-Heusler compound exhibits half-metallic behavior, characterized by a wide band gap of 3.4 eV in the spin-up channel and an optimized lattice parameter of 6.1 Å, together with a total magnetic moment of 3 μB per formula unit that fully obeys the Slater–Pauling rule, thereby demonstrating robust ferromagnetic ordering. The optical analysis reveals distinct absorption responses across the ultraviolet, visible, and infrared regions, with well-defined features in the dielectric function, refractive index, optical conductivity, reflectivity, and electron energy loss spectra, indicating strong potential for optoelectronic integration. Moreover, the thermoelectric transport properties, including the Seebeck coefficient, electrical conductivity, and power factor, exhibit a pronounced temperature dependence, with enhanced performance at elevated temperatures, underscoring the material’s suitability for energy harvesting and waste-heat recovery. Collectively, these findings establish LiVN as a multifunctional compound with promising applications in spintronics, optoelectronics, and thermoelectric energy systems.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 10","pages":"4239 - 4251"},"PeriodicalIF":1.7,"publicationDate":"2026-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148909807","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":"Structure, electronic, magnetic and optical properties of cation-substituted CdMnxSn1-xP2","authors":"Anuj Kumar,&nbsp;Aman Kumar,&nbsp;Sandeep Kumar Pundir,&nbsp;Nempal Singh","doi":"10.1007/s12648-026-04100-w","DOIUrl":"10.1007/s12648-026-04100-w","url":null,"abstract":"<div><p>Detailed first-principles spin-polarized density functional theory (DFT) calculations were performed using full potential linearized augmented plane wave (LP-LAPW) method to study the structural, electronic, magnetic, and optical properties of CdMn_xSn_1-xP₂ compound for Mn concentration range of <span>(0le x le 0.5)</span>. Generalized gradient approximation - Perdew-Burke-Ernzerhof (GGA-PBE) and Tran-Blaha modified Becke-Johnson (TB-mBJ) functional was employed for the exchange-correlation potential. The Mn-doped compound exhibits a half-metallic character in conjunction with p-type semiconducting behavior. The calculated results shows that an increase in Mn concentration in CdSnP₂ results in an increase in the band gap in spin-down state. In contrast, the other spin state show a degenerate semiconducting nature, characterized by an effectively zero band gap. Mn<span>(rightarrow )</span>Sn (IV–IV substitution) is feasible; however, this configuration is more likely to be linked to defect formation. The magnetic moment per atom increases linearly with dopant concentration. The optical properties of the Mn-doped CdSnP₂ compounds were analyzed by dielectric function, refractive index, absorption spectra, and optical conductivity. The calculated results indicate the compound exhibits lower optical activity in the infrared (IR) region, while demonstrating higher activity in the visible and ultraviolet (UV) regions. These characteristics suggest potential applications of the compound in the design and engineering of optoelectronic and spintronics semiconductor devices, which offer promising opportunities for technological advancement.</p></div>","PeriodicalId":584,"journal":{"name":"Indian Journal of Physics","volume":"100 11","pages":"4611 - 4625"},"PeriodicalIF":1.7,"publicationDate":"2026-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149163137","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}