Solid State Communications最新文献

Understanding the thermal transport behaviors in the crystal lattice is important for designing semiconducting materials in thermal management. In this work, we investigate the mechanism of the decrease in thermal properties of β-FeSi₂ when Co dopant is introduced to the host crystal. The crystallite size decreases as Co doping increases from 0 to 5 %. The micro-strain and stress increase with increasing doping levels. The decrease in crystallite size and increase in micro-strain/stress indicate the origin of phonons scattering and lattice softening, leading to the reduction in thermal conductivity. This study provides insights into the correlation between the crystal properties evolution and thermal transport in metal silicide compounds which could be useful in thermal-to-energy conversion applications.

A comprehensive study of lead-free halide double perovskite using density functional theory (DFT) including structural, electronic, dynamical, mechanical, optical, and thermoelectric properties has been carried out. The tolerance factor and the octahedral factor confirm that the compound belongs to face-centred-cubic structure with Fm-3m space group. The predicted band structure and DOS exhibit that the material is an indirect bandgap semiconductor. Our calculation reveals that material is dynamically stable because of no negative frequency found in phonon-dispersion curve. The material also possesses mechanical stability. The optical spectra of material show good absorbance and low reflectivity in ultraviolet region. The thermoelectric part discusses the Seebeck coefficient, thermal conductivity, electrical conductivity, power factor, and figure of merit (zT) at different chemical potential into temperature range 400–1200 K. The purpose of this investigation is to stimulate researchers to develop this kind of material and assess their potential for the advancement of contemporary thermoelectric and optoelectronic devices.

Double perovskites have gathered momentous attention due to their structural, optoelectronics, and thermal properties. FP-LAPW + lo technique was employed along with the PBEsol-GGA and TB-mBJ potential. The optimized parameters and E-V parabolic curve were computed employing Birch Murnaghan's equation of state (BM-EOS). The negative formation energy E_f for Rb₂YCuCl₆ and Cs₂YCuCl₆ confirms the thermodynamic stability of these double perovskites. The mechanical stability of both compounds was confirmed by their elastic constants $C_{ij}$, Pugh's ratio, and anisotropy. The indirect band plots of Rb₂YCuCl₆ (2.57eV) and Cs₂YCuCl₆ (2.39eV) double perovskites confirm the semiconductor nature. The optical properties like dielectric function, reflectivity, optical conductivity, absorption coefficient, and energy loss function were determined within an energy range of up to 18 eV. The high absorption spectra for the under-study compounds 147.21 × 10⁴ cm⁻¹ at 14.60 eV for Rb₂YCuCl₆ and 261.30 × 10⁴ cm⁻¹ at 15.57 eV for Cs₂YCuCl₆ lies in the far UV region determines its potential use in the high-frequency devices. The thermoelectric properties such as the Seebeck coefficient, ZT, and power factor, are investigated using the semi-classical Boltzmann theory implemented in the BoltzTrap code. The peak value of ZT for Rb₂YCuCl₆ is 0.38 and for Cs₂YCuCl₆ is 0.33. The suggested findings indicate that Rb₂YCuCl₆ and Cs₂YCuCl₆ are potential candidates for thermoelectric and photovoltaic applications.

We use time-dependent Ginzburg–Landau theory in a three-dimensional model, including thermal noise, to analyze angle-dependent Hall resistivity and longitudinal resistivity of type-II superconductor. The Hall resistivity and longitudinal resistivity are calculated as functions of temperature, magnetic field and the angle $\theta$ between the magnetic field and the ab-plane in the vortex-liquid regime. Our theoretical calculations within a self-consistent fluctuation approximation for MgB₂ and HgBa₂CaCu₂O₆ materials are in good agreements with the experimental findings for both below and above the critical temperature $T_c$. We observe that when the field angle decreases, the transition temperature increases and the magnitude of longitudinal resistivity decreases, which is qualitatively comparable to decrease of the perpendicular field component. However, when the magnetic field direction approaches the layer surface, it shows a clear different effect from that of a perpendicular field with the same normal component.

Occupancy tendencies of elements significantly differ in precipitation-strengthened Ni-based, CoNi-based, and Co-based alloys, which further affect the γ/γ′ lattice misfit and mechanical properties, but relevant research is lacking. In this work, occupancy tendencies of doping elements (Ta, W, Cr, Fe, Mo, Re, Ti, V) and lattice misfit of γ and γ′ phases in precipitation-strengthened alloys dependent on Co/CoNi ratios have been systematically studied through first-principles calculations. The results show that the tendency of all eight elements to occupy the γ′-Al sublattice site increases with the increase of the Co/CoNi ratio, and the tendency to occupy the γ-Ni/Co site all decreases. The occupancy tendencies of these elements exhibit a strong correlation with the Co/CoNi ratio. Lattice misfit gradually increases as the Co/CoNi ratio is raised. Notably, element Ta has the greatest influence on lattice misfit. The appropriate Co/CoNi ratio is conducive to synergistically enhancing high entropy effects and lattice distortion effects for matrix and Ni₃Al precipitate phase, and regulating reasonable lattice misfit, which is beneficial for the design of precipitation-strengthened alloys with excellent strength-ductility balance.