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Electronic and thermoelectric properties of YbMg_(2)X_(2)(X=P,As,Sb,Bi)zintl compounds by first-principles method

Journal of Rare Earths 2024年第1期42卷 147-154,I0006页

作者： Sajid Khan Dil Faraz Khan R.Neffati Tariq Usman Muhammad Waqar Ahsraf Shamim Khan Saeed Ullah Jan g.murtaza Department of Physics University of Science&Technology BannuBannu28100Pakistan Department of Physics Faculty of ScienceKing Khalid UniversityP.O.Box 9004AbhaSaudi Arabia Laboratoire de Physique de La Matiere Condensee Departement de PhysiqueFaculte des Sciences de TunisUniversite Tunis El ManarCampus Universitaire1060TunisTunisia Department of Physics Shaoxing UniversityShaoxing312000China Department of Mathematics&Natural Sciences Prince Mohammad Bin Fahd UniversityAlkhobar31952Saudi Arabia Materials Modeling Lab Department of PhysicsIslamia College Peshawar25120KhyberPakhtunkhwaPakistan

In this work the structural,electronic and thermoelectric properties of YbMg_(2)X_(2)(X=P,As,Sb,Bi)zintl compounds were investigated comprehensively using first principles *** electronic properties were studied using PBE ggA,TB-mBJ and hybrid(YS-PBE0)*** the structural parameters of optimized structures are in harmonious agreement to the available *** band structure study illustrates that the titled materials manifest metallic and semi metallic nature using PBE and TB-mBJ potentials while they show wide band gap semiconducting behavior by following hybrid(YS-PBE0)*** density of states(TDOS)and partial density of states(PDOS)were also calculated to glimpse the contribution of orbitals of atoms in the formation of *** properties were studied by using BoltzTraP2 code employed to *** get enormous values of Seebeck coefficient(S),power factor(PF)and thermoelectric figure of merit(ZT)for all the samples YbMg_(2)X_(2)(X=P,As,Sb,Bi),Moreover,the overwhelming transport properties for the titled compounds indicate the optimum level of carriers’concentration which pinpoints these materials to be better thermoelectrics in the 1-2-2 zintl family.

关键词： Zintl compounds Hybrid functional Band structure Thermoelectrics Rare earths

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Kinetic Instability of Anisotropic Drift Wave Accompanied by Field Aligned Currents in Solar Coronal Loop

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Communications in Theoretical Physics 2018年第10期70卷 470-476页

作者： Hafsa Naim Ch.Uzma g.murtaza Salam Chair Department of Physics GC University

Solar coronal loops are frequently accompanied by the field-aligned currents, which drive instabilities if the drift velocity u0 > v A the Alfv′en velocity. For our choice of parameters, the critical threshold value of u0/v A is ～ 3.0 for growth and the corresponding current filling factor ～ 10-3-10-4. Below this value we are no longer in the kinetic *** coronal loops also have short-scale density gradients within each loop. The electron resonance in the presence of density gradient causes the drift mode to grow. We study the effect of these two free energy sources, the electron drift and the density gradient, in the presence of temperature anisotropy T⊥_α > T∥_α. These effects simultaneously exist in the coronae. Using gyrokinetic theory, we investigate the influence of these effects, examine how they interplay with each other and study the consequent growth of the magnetosonic wave. We observe that kinetic instability driven by density gradient can be suppressed by field-aligned currents. The temperature anisotropy with chosen signatures causes further stabilizing effect. The results may prove useful to study the heating mechanism of solar coronal loops, acceleration of particles and confinement of particles in the thermonuclear reactors.

关键词：运动不稳定性花冠飘移电流排列太阳各向异性波浪

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Linear Analysis of Obliquely Propagating Longitudinal Waves in Partially Spin Polarized Degenerate Magnetized Plasma

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Communications in Theoretical Physics 2017年第12期67卷 791-797页

作者： Z.Iqbal g.murtaza A.Hussain Salam Chair Department of Physics G.C. University Lahore Department of Physics Mirpur University of Science and Technology

Linear analysis of low frequency obliquely propagating electrostatic waves in a partially spin polarized degenerate magnetized plasma is presented. Using Fourier analysis, a general linear dispersion relation is derived for low frequency electrostatic lower hybrid(LH) wave, ion acoustic(IA) wave and ion cyclotron(IC) wave in the presence of electron spin polarization. It is found that the electron spin polarization gives birth to a new spin-dependent wave(spin electron acoustic wave) in the spectrum of these waves. Further, the electron spin polarization also causes drastic shifts in the frequency spectrum of these waves. These effects would have a strong bearing on wave phenomena in degenerate astrophysical plasmas.

关键词： spin polarization longitudinal waves degenerate plasma

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Ordinary Mode Instability in a Cairns Distributed Electron Plasma

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Communications in Theoretical Physics 2018年第6期69卷 699-703页

作者： K.Azra Z.Iqbal g.murtaza Salam Chair Department of PhysicsG.C.UniversityLahore 54000Pakistan

Employing the linearized Vlasov-Maxwell equations, a generalized dispersion relation for the ordinary mode is derived by employing the Cairns distribution function. The instability of the mode and its threshold condition is investigated. It is found that the temperature anisotropy χ = T_∥/T_⊥ > 1 required to excite the instability varies with density values whereas the growth rate is dependent on various parameters like non-thermality Λ, equilibrium number density n_0 and temperature anisotropy. It is found that with the increase in the values of any of the parameters Λ, n_0 and χ, the growth rate is enhanced and the k-domain is enlarged. The results are applicable for space plasma environments like solar wind.

关键词：不稳定性血浆分布式电子生长率线性化温度密度

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Electronic Band Structure and Optical Response of Spinel SnX_(2)O_(4)(X=Mg,Zn)through Modified Becke-Johnson Potential

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Chinese Physics Letters 2013年第4期30卷 177-180页

作者： A.Manzar g.murtaza R.Khenata S.Muhammad Hayatullah Department of Physics Hazara University MansehraKPKPakistan Materials Modeling Lab Department of PhysicsIslamia College UniversityPeshawarPakistan LPQ3M Laboratory Institute of Science and TechnologyUniversity of MascaraAlgeria Department of Physics and Astronomy King Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

The modified Becke–Johnson exchange potential approximation is applied to predict the band structure,optical parameters and electron density of SnMg_(2)O_(4)and SnZn_(2)O_(4).The local density approximation,generalized gradient approximation(ggA),EV-ggA significantly underestimate the direct band gap values compared to modified Becke–Johnson *** band gap dependent optical parameters such as dielectric constant,index of refraction,reflectivity,and optical conductivity are calculated and analyzed.A prominent feature of cation replacement is observed and analyzed for these studied *** replacement of the cation Mg by Zn leads to a significant reduction in the value of band gap and consequently affects its dependant optical *** variation is of crucial importance for device fabrication in different regions of the spectrum.

关键词： approximation (4) Modified

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Electronic Band Profile and Optical Response of Spinel MgIn_(2)O_(4)through Modified Becke-Johnson Potential

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Chinese Physics Letters 2013年第6期30卷 190-193页

We employ the first-principles technique based on the modified Becke–Johnson(BJ)exchange potential for the prediction of the electronic band structure,optical properties,and electron density of the cubic MgIn_(2)O_(4)spinel *** is found that the calculated band gap value with the modified BJ approximation is significantly improved over the results based on the generalized gradient approximation and the local density approximation in comparison to the experimental *** band gap dependent optical parameters such as the dielectric constant,refractive index,reflectivity,optical conductivity,and electron density are *** optical response suggests that MgIn_(2)O_(4)is an applicant material in optoelectronic devices in various parts of the energy spectrum like MgAl_(2)O_(4)and Mgga_(2)O_(4).

关键词： approximation Modified reflectivity

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Electronic and Optical Properties of Spinel geMg2O4 and geCd2O4

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Chinese Physics Letters 2013年第12期30卷 134-138页

Oxide spinels have potential applications in optoelectronics and optics *** this work the electronic band structure and optical properties of geMg2O4 and geCd2O4 are calculated by first principles technique based on the new potential approximation known as the modified Becke-Johnson exchange potential approximation(mBJ).The local density and generalized gradient approximations significantly underestimate the direct band gap values compared to the *** band gap dependent optical parameters such as dielectric constant,refractive index,reflectivity and optical conductivity are calculated and *** replacement of the cation is observed and analyzed for the compounds studied and a prominent change is *** replacement of the cation Mg by Cd reduces the band gap and its dependent optical *** device fabrication in different regions of the spectrum this variation is strongly recommended.

关键词： approximation potential reflectivity

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glow Discharge Plasma Nitriding of AISI 304 Stainless Steel

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Plasma Science and Technology 2007年第4期9卷 463-468页

作者： A.QAYYUM M.A.NAVEED S.ZEB g.murtaza M.ZAKAULLAH National Tokamak Fusion Program IslamabadPakistan Department of Physics Quaid-i-Azam University45320 IslamabadPakistan Salam Chair in Physics Government College University54000 LahorePakistan

glow discharge plasma nitriding of AISI 304 austenitic stainless steel has been carried out for different processing time under optimum discharge conditions established by spectroscopic analysis. The treated samples were analysed by X-ray diffraction （XRD） to explore the changes induced in the crystallographic structure. The XRD pattern confirmed the formation of an expanded austenite phase （TN） owing to incorporation of nitrogen as an interstitial solid solution in the iron lattice. A Vickers microhardness tester was used to evaluate the surface hardness as a function of indentation depth （μm）. The results showed clear evidence of surface changes with substantial increase in surface hardness.

关键词： optical diagnostics plasma nitriding austenitic stainless steel

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Structural and Optoelectronic Properties of Cubic CsPbF3 for Novel Applications

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Chinese Physics Letters 2011年第11期28卷 232-235页

作者： g.murtaza Iftikhar Ahmad M.Maqbool H.A.Rahnamaye Aliabad A.Afaq Materials Modeling Laboratory Department of PhysicsHazara UniversityMansehraPakistan Department of Physics University of MalakandChakdaraPakistan Department of Physics and Astronomy Ball State UniversityIndianaUSA Department of Physics Sabzevar Tarbiat Moallem UniversitySabzevarIran Center of Excellence in Solid State Physics Qua-e-Azam CampusLahorePakistan

Chemical bonding as well as structural,electronic and optical properties of CsPbF3 are calculated using the highly accurate full potential linearized augmented plane-wave method within the framework of density functional theory(DFT).The calculated lattice constant is found to be in good agreement with the experimental *** electron density plots reveal strong ionic bonding in Cs-F and strong covalent bonding in *** calculations show that the material is a direct and wide bandgap semiconductor with a fundamental gap at the R-symmetry *** properties such as the real and imaginary parts of the dielectric function,refractive index,extinction coefficient,reflectivity,optical conductivity and absorption coefficient are also *** on the calculated wide and direct bandgap,as well as other optical properties of the compound,it is predicted that CsPbF_(3) is suitable for optoelectronic devices and anti-reflecting coatings.

关键词： bonding coefficient imaginary

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FirstPrincipleCalculations of the ground and Excited State Properties of RbPbF_(3)

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Chinese Physics Letters 2013年第9期30卷 128-131页

作者： Hayatullah g.murtaza R.Khenata S.Naeem M.N.Khalid S.Mohammad Materials Modeling Lab Hazara UniversityMansehraPakistan Materials Modeling Lab Department of PhysicsIslamia College UniversityPeshawarPakistan LPQ3M Laboratory Institute of Science and TechnologyUniversity of MascaraAlgeria Department of Physics and Astronomy King Saud UniversityP.O.Box 2455Riyadh 11451Saudi Arabia

Structural,elastic,electronic,chemical bonding and optical properties of the cubic RbPbF 3 compound under pres-sure are studied using a highly accurate state-of-the-art full potential linearized augmented plane wave *** exchange correlation effects are included through the generalized gradient and modified Becke–Johnson ex-change *** lattice constant and band gap of the cubic RbPbF 3 decreases with enhanced *** 3 is brittle,elastically anisotropic,and a direct bandgap *** optical properties such as refractive index𝑜(ω),extinction coefficient𝑙(ω),reflectivity𝑆(ω),and optical conductivity𝜏(ω)are predicted.

关键词： potential. material. method.

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