Indian Journal of Physics最新文献

The objective is to determine the structural, elastic, electronic, magnetic and thermodynamic properties of new half-metallic Cr₂RbGe, Cr₂RbIn and Cr₂RbSb by using the full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory and implemented in WIEN2K code. The exchange–correlation potential is evaluated using the generalized gradient approximation (GGA) within the Perdew-Burke-Ernzerhof (PBE) parameterization. Results on lattice parameters, bulk modulus, elastic, energy band gap and magnetic properties are reported. The elastic properties have shown the conformity of elastic constants with the stability criteria and the ductile nature of the compounds. The electronic band structures and density of states (DOS) of the compounds indicate they are half metallic because of the existence of the energy gap in the minority spin (DOS and band structure), which yields perfect spin polarization. These compounds Cr₂RbZ (Z = Ge, In and Sb) are found to be Half-metallic in the spin-down channel and metallic in the spin-up channel, which leads to a spin polarization of 100% with a integer magnetic moment of 8.00 μ_B, 8.00 μ_B and 9.00 μ_B for Cr₂RbGe, Cr₂RbIn and Cr₂RbSb respectively, is mainly contributed by the Cr atom. The thermodynamic stability of these compounds are also determined. In addition the temperature and pressure effects on the bulk modulus, heat capacities, Debye temperatures and entropy are computed and discussed in details, temperature and pressure dependence of thermodynamic properties of these materials have been examined in the ranges (0–1000 K) and (0–16 GPa), respectively. All the aforementioned results indicate that this new compounds would be an ideal candidate in spintronic.

Atmospheric pressure dielectric barrier discharge is established to optimize discharge conditions, transitioning from filamentary mode to a stable discharge appearance. The uniform discharge, characterized by numerous beneficial properties, is advantageous for the modification of material surfaces. To generate the discharge, disc electrodes are linked to a variable high-power supply capable of delivering up to 42 kV at 50 Hz. Oxygen gas is introduced into the reactor at a consistent flow rate of 70 ml/min, with discharge gaps ranging from 1 to 4 mm. Two glass dielectrics, wire-meshes and Polyethylene Terephthalate films were utilized to cover both electrodes. The results indicate that filamentary discharge at 27 kV advances into a uniform discharge under atmospheric pressure. When Polycaprolactone was subjected to optimal discharge conditions, contact angle measurements showed a reduction as discharge time increased.

This research comprehensively investigates the structural, optical, and electrochemical properties of nickel oxide (NiO) nanoparticles, focusing on its potential applications in energy storage systems, particularly electrochemical double-layer capacitors (EDLCs). In a single-step hydrothermal process, two-dimensional (2D) NiO nanoparticles was synthesized using carbon templates. X-ray diffraction analysis confirmed NiO nanoparticle’s crystalline nature, revealing a crystallite size of approximately 35 nm. Optical characterization unveiled NiO nanoparticle’s distinctive absorption pattern in the UV region, with additional absorbance observed in the visible region, and a calculated band gap of 2.6 eV. Morphological studies depicted a unique 2D nanosheets structure for NiO nanoparticles, with microstructural images showing fringe patterns and selected area electron diffraction patterns indicating its polycrystalline nature. NiO nanoparticles exhibit excellent electrochemical performance, including high specific capacitance, which is crucial for efficient energy storage. Their unique 2D nanosheet structure enhances surface area and facilitates better charge transport, making them ideal for EDLCs. Additionally, the reduced band gap of NiO nanoparticles, as determined in this study, improves their conductivity and overall electrochemical behavior. These novel attributes position NiO nanoparticles as superior materials for advancing the performance and efficiency of energy storage devices. Crucially, NiO nanoparticles exhibited a high specific capacitance of 13 F/g, highlighting its suitability for EDLCs. This finding positions NiO nanoparticles as a promising candidate for energy storage applications, advancing the field of supercapacitors. Electrochemical analysis through cyclic voltammetry and Nyquist plots further elucidated the material's potential in energy storage applications. This interdisciplinary exploration enriches our understanding of NiO nanoparticles and underscores its utility in emerging energy storage technologies, guiding further advancements in supercapacitor systems for sustainable energy solutions.

We introduce a novel class of random stationary, scalar source for producing far field with ring-shaped intensity profile, named as circularly symmetric Hermite-Gaussian correlated Schell-model (CSHGCSM) source. The analytical expressions for the cross-spectral density (CSD) function of a CSHGCSM beam propagating in free space and in linear isotropic random media are derived, respectively. It is shown that the CSHGCSM beam exhibits a robust ring-shaped profile in far field, and three-dimensionally (3D) optical cage could be obtained when the CSHGCSM beam focused by a thin lens. The optical cage length is dependent on parameters of mode order n, transverse coherence width δ, focal length f, and beam wavelength λ. Furthermore, it is demonstrated that the CSHGCSM beam propagating in linear random media at small distance from the source exhibits annular profile, then converts into Gaussian beam as the propagation distance increases. There is a phenomenon of regenerative oscillation for the spectral degree of coherence (SDOC) of the CSHGCSM beam in the presence of random media.

In this work, synthesis and characterization of Eu_xYb_1−xZn₂Sb₂ (0 ≤ × ≤ 1.0) systems under microwave irradiation method. Herein, microwave technique offers ecological merit in the synthesis of thermoelectric materials such as short duration (25 min). The synthesized samples were analyzed by their XRD, SEM, EDX, Seebeck coefficient, electrical conductivity, and Hall voltage measurements. The microwave synthesis of compounds by doping Eu into YbZn₂Sb₂ and their properties are extensively discussed. It was found that the microwave irradiation acts to accelerate the reactions induced by fast heat surrounding susceptor of primary components and give large quaternary ingots. The XRD data revealed that the synthesized compounds crystallized in a hexagonal structure where ZnSb precipitated as a secondary phase in almost all the synthesized adopted compounds. Furthermore, a maximum PF of 26.27 μW/cmK² at 518 K was acquired for Eu_0.6Yb_0.4Zn₂Sb₂ sample with carrier concentration of 5.11 (times ) 10²¹ cm⁻³ at 300 K.

The quantum efficiency of GaN/ Al_xGa_1−xN/GaN superlattice (SL) UV-LED is reduced as a result of temperature rise in the active region of the LED. Self-heating of the device due to the temperature rise strengthens non-radiative processes, low internal efficiency, and a small lifetime of the LED. In this work, it is found that poor heat dissipation from the device due to low thermal conductivity (k) of the SL is one reason for temperature rise. In this investigation, we found that a 15% enhancement in k reduces a 7% temperature rise. A strategy of structural optimization has been carried out to demonstrate the improvement in k. It can be improved by managing the well barrier thickness ratio (r) in the SL. In this study, we found that for r < 1, k shows considerable enhancement. This well barrier thickness tailoring technique has two significant consequences: 1. improvement in k; 2. suppression of the detrimental effect of polarization on k. This work suggests that composition x, and structural optimization (well barrier thickness engineering), have a vital role in thermal conductivity management in SL, which can reduce the rise in temperature resulting in the high quantum efficiency of the UV-LED.

We propose a (U(1)_L) model based on (A_4) symmetry aiming to explain the smallness of neutrino masses as well as the quark and lepton mixing patterns. The smallness of Majorana neutrino mass is reproduced through the combination of type-I and -II seesaw mechanisms. The model can accommodate the current observed patterns of lepton and quark mixing in which the solar neutrino mixing angle and the Dirac CP violating phase are in (3sigma ) range for both normal hierarchy and inverted hierarchy, the Majorana violating phases are predicted to be (eta _{1} in (0.00, 9.76)^circ ) and (eta _{2} in (68.70, 270.00)^circ ) for normal hierarchy while (eta _1in (0.00, 10.83)^circ ) and (eta _{2} in (78.60, 90.00)^circ ) for inverted hierarchy. The obtained sum of neutrino mass and the effective Majorana neutrino mass are in good consistent with the recent limits. For quark sector, all the quark masses can get the best-fit values and all the elements of the quark mixing matrix are in agreement with the experimental constraints except the element ( (V_{{{text{CKM}}}} )_{{21}} ) with a deviation about (0.25,%).

The current study explores the Sharma-Mittal holographic dark energy (SMHDE) by considering Bianchi-(VI_0) space-time in Saez-Ballester’s theory. The model’s exact solutions are procured by assuming the relationship between metric potentials. The Hubble horizon is regarded as the Infrared cutoff to examine our model’s cosmic effects. The physical behavior of the model is investigated by considering two fluids- SMHDE and pressureless matter. The behavior of the cosmological parameters, such as the deceleration parameter, EoS parameter, (rho _{de}), (rho _m), statefinder, and (v_s^2), was evaluated with the help of their plots with respect to redshift(z) to study the nature of the universe. The figure of the deceleration parameter predicts that the present model transits from the deceleration to the acceleration period of the universe. The EoS parameter for this model agrees with the recent astrophysical observations, which lie within the range of quintessence region. In the case of statefinder and (v_s^2), the model shows Chaplygin gas and stability throughout the region. The perturbation technique is used to evaluate the stability of the resulting model. Finally, the results of the current model support the existence of an accelerating universe with the present observational data.

The effects of a magnetic field on the Rashba spin–orbit interaction in an asymmetry quantum well is theoretically studied, and the expression of the ground state energy of the magnetopolaron is obtained within Pekar variational method. The ground state energy of the magnetopolaron splits into two branches due to the Rashba effect, and the energy splitting appears saturated state with the increase of the well width. Because the contribution of the magnetic field cyclotron resonance frequency to the Rashba spin–orbit splitting is a positive value, the energy splitting distance becomes larger as the magnetic field cyclotron resonance frequency increases. Due to the spin–orbit interaction, the energy splits at zero magnetic field. The total energy is reduced due to the existence of phonons. Therefore, the polaron state is more stable than the bare electron state, and the polaron energy splitting is more stable.

In this paper, we compare pure and doped GaN under spin ferromagnetic and non-magnetic calculations using the Full Potential Linearized Augmented Plane-wave method and the state-of-the-art computational code WIEN2k. Structural and opto-electronic aspects of GaN have been studied by implications of corresponding potentials and exchange–correlation energy functional. Though, to yield bandgaps in good agreement with the experiment study, Tran–Blaha modified Becke–Johnson (mBJ) potential has been employed. In order to determine the band gap, reflectivity, refraction, refraction index, lattice constant, dielectric constant, and energy loss spectrum for GaN, these simulations were carried out. Good agreement with experimental measurements has been observed throughout this investigation. In addition, O-doped GaN exhibits prominent absorption peaks in the high energy region, indicating potential applications in UV optoelectronics and spintronics.