Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_...Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_(4)(Z=S,Se)in a systematic manner is essential for the strategic advancement of spin polarized current in a spintronic device.In this recent study,the WIEN2K code was employed to comprehensively analyze these properties.The calculated lattice constants,obtained using the generalized gradient approximation(GGAsol-PBE),closely match experimental findings of the similar family compounds.The examination of the stability of ferromagnetic states in the ground state involves comparing energies between anti-ferromagnetic and ferromagnetic states.Moreover,an assessment of the stability of the cubic phase in both spinels was conducted using analyses of the phonon dispersion curve,formation energy and Born stability criteria.The ductility characteristics were examined through the calculation of Poisson's and Pugh's ratios.Furthermore,details regarding the density of states,spin polarization,ex-change coupling and Curie temperature were provided to explore the characteristics associated with ferromagnetism.Potential optoelectronic applications were proposed,leveraging the direct band gaps of 1.4 and 1.0 eV for HgNd_(2)Z_(4)(Z=S,Se)respectively,within the visible spectrum.Particularly noteworthy is the effective light absorption of HgNd2Se4 in the visible range,characterized by prominent peaks that facilitate the transition of electrons from the valence band(VB)to the conduction band(CB).Additionally,the study extends to thermoelectric characteristics,determining various factors such as Seebeck coef-ficient(S),figure of merit(ZT),electrical and thermal conductivities of the evaluated spinels.展开更多
This paper presents an experimental investigation of the mechanical and tribological properties of Cu-graphene nanosheets(GN)nanocomposites.We employed the electroless coating process to coat GNs with Ag particles to ...This paper presents an experimental investigation of the mechanical and tribological properties of Cu-graphene nanosheets(GN)nanocomposites.We employed the electroless coating process to coat GNs with Ag particles to avoid its reaction with Cu and the formation of intermetallic phases.We analyzed the effect of GN content on the structural,mechanical,and tribological properties of the produced nanocom-posites.Results showed that the electroless coating process is an efficient technique to avoid the reaction between Cu and C and the formation of intermetallic phases.The addition of GNs significantly improves the mechanical and tribological properties of Cu nanocomposites.However,the addition of GNs needs to be done carefully because,after a certain threshold value,the mechanical and tribological properties are negatively affected.The optimum GN content is determined to be 0.5vol%,at which hardness,wear rate,and coefficient of friction are im-proved by 13%,81.9%,and 49.8%,respectively,compared with Cu nanocomposites.These improved properties are due to the reduced crys-tallite size,presence of GNs,and homogenous distribution of the composite constituents.展开更多
This paper presents a computational study of the air flow past a triangular boattailed projectile.The study shows that there is a single normal shock wave impinges the projectile at transonic speeds.At supersonic spee...This paper presents a computational study of the air flow past a triangular boattailed projectile.The study shows that there is a single normal shock wave impinges the projectile at transonic speeds.At supersonic speeds,the formed shock waves are smeared compared to a conical boattailed projectile.Also,there is a reduction of the wake region behind the triangular base and the rear stagnation point is nearer to the projectile base resulting in base drag reduction.Moreover,there is an improvement of the stability of the triangular boattailed projectile since a lower overturning moment is incurred.展开更多
基金the Deanship of Scientific Research at King Khalid University for funding this work through large group Research Project under grant number RGP2/450/44。
文摘Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_(4)(Z=S,Se)in a systematic manner is essential for the strategic advancement of spin polarized current in a spintronic device.In this recent study,the WIEN2K code was employed to comprehensively analyze these properties.The calculated lattice constants,obtained using the generalized gradient approximation(GGAsol-PBE),closely match experimental findings of the similar family compounds.The examination of the stability of ferromagnetic states in the ground state involves comparing energies between anti-ferromagnetic and ferromagnetic states.Moreover,an assessment of the stability of the cubic phase in both spinels was conducted using analyses of the phonon dispersion curve,formation energy and Born stability criteria.The ductility characteristics were examined through the calculation of Poisson's and Pugh's ratios.Furthermore,details regarding the density of states,spin polarization,ex-change coupling and Curie temperature were provided to explore the characteristics associated with ferromagnetism.Potential optoelectronic applications were proposed,leveraging the direct band gaps of 1.4 and 1.0 eV for HgNd_(2)Z_(4)(Z=S,Se)respectively,within the visible spectrum.Particularly noteworthy is the effective light absorption of HgNd2Se4 in the visible range,characterized by prominent peaks that facilitate the transition of electrons from the valence band(VB)to the conduction band(CB).Additionally,the study extends to thermoelectric characteristics,determining various factors such as Seebeck coef-ficient(S),figure of merit(ZT),electrical and thermal conductivities of the evaluated spinels.
基金funded by the Deanship of Scientific Re-search(DSR)at King Abdulaziz University,Jeddah,under grant No.G:455-135-1440.
文摘This paper presents an experimental investigation of the mechanical and tribological properties of Cu-graphene nanosheets(GN)nanocomposites.We employed the electroless coating process to coat GNs with Ag particles to avoid its reaction with Cu and the formation of intermetallic phases.We analyzed the effect of GN content on the structural,mechanical,and tribological properties of the produced nanocom-posites.Results showed that the electroless coating process is an efficient technique to avoid the reaction between Cu and C and the formation of intermetallic phases.The addition of GNs significantly improves the mechanical and tribological properties of Cu nanocomposites.However,the addition of GNs needs to be done carefully because,after a certain threshold value,the mechanical and tribological properties are negatively affected.The optimum GN content is determined to be 0.5vol%,at which hardness,wear rate,and coefficient of friction are im-proved by 13%,81.9%,and 49.8%,respectively,compared with Cu nanocomposites.These improved properties are due to the reduced crys-tallite size,presence of GNs,and homogenous distribution of the composite constituents.
文摘This paper presents a computational study of the air flow past a triangular boattailed projectile.The study shows that there is a single normal shock wave impinges the projectile at transonic speeds.At supersonic speeds,the formed shock waves are smeared compared to a conical boattailed projectile.Also,there is a reduction of the wake region behind the triangular base and the rear stagnation point is nearer to the projectile base resulting in base drag reduction.Moreover,there is an improvement of the stability of the triangular boattailed projectile since a lower overturning moment is incurred.
