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International Journal of minerals,metallurgy and materials 2013年第2期20卷 166-171页

作者： Ghulam Ali Saadat A.Siddiqi shahid m.ramay shahid Atiq murtaza Saleem Centre of Excellence in Solid State Physics University of the Punjab Interdisciplinary Research Centre in Biomedical materials COMSATS Institute of Information Technology Chemical Engineering Department College of EngineeringKing Saud University

Cobalt （Co）-doped ***3 multiferroics were synthesized by a sol-gel method based on the auto- combustion technique. As-synthesized powder was examined using various characterization techniques to explore the effect of Co substitution on the properties of Bi0.9La0.1FeO3. X-ray diffraction reveals that Co-doped Bi0.9La0.1FeO3 preserves the perovskite-type rhombohedral structure of BiFeO3, and the composition without Co preserves the original structure of the phase; however, a second-phase Bi2Fe409 has been identified in all other compositions. Surface morphological studies were performed by scanning electron microscopy. Temperature-dependent resistivity of the samples reveals the characteristic insulating behavior of the multiferroic material. The resistivity is found to decrease with the increase both in temperature and Co content. Room temperature frequency-dependent dielectric measurements were also reported. magnetic measurements show the enhancement in magnetization with the increase in Co content.

关键词： multiferroics cobalt doping microstructure electric properties magnetic properties sol-gel process

Origin of Ferromagnetism in Al and Ni Co-doped ZnO Based DmS materials

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Chinese Physics Letters 2012年第10期29卷 155-157页

作者： murtaza Saleem Saadat A.Siddiqi shahid m.ramay shahid Atiq Shahzad Naseem Centre for Solid State Physics University of the PunjabQuaid-e-Azam CampusLahore 54590Pakistan 2Interdisciplinary Research Centre in Biomedical MaterialsCOMSATS Institute of Information TechnologyDefence RoadOff Raiwind RoadLahorePakistan 3Department of Chemical EngineeringCollege of EngineeringKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia

Zn0.95Ni0.05O and Zn0.90Ni0.05Al0.05O compositions of nanocrystallites are synthesised using the well recognised auto-combustion *** x-ray diffraction patterns demonstrate the phase pure characteristic wurtzite-type crystal structure with space group P63mc in both the *** elemental incorporation of Ni and Al contents into the ZnO structure is confirmed by energy dispersive x-ray *** micrographs of scanning electron microscopy show an approximate ordered *** electrical resistivity is observed to decrease with the rising temperature,depicting the characteristic semiconductor behaviour of the *** lower values of resistivity and ferromagnetic interactions in the Al-doped sample correspond to an increase of carrier's *** is observed that the carrier mediated mechanism is mainly responsible for ferromagnetism in ZnO-based diluted magnetic semiconductors.

关键词： resistivity diluted Origin

Synthesis,Structural and Optical Properties of mn-Doped Ceria Nanoparticles:A Promising Catalytic material

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Acta metallurgica Sinica(English Letters) 2016年第3期29卷 265-273页

作者： Anees A.Ansari Joselito P.Labis manawwer Alam shahid m.ramay Naushad Ahmad Asif mahmood King Abdullah Institute for Nanotechnology King Saud University Research Center College of ScienceKing Saud University Department of Physics King Saud University College of Engineering Department of Chemical EngineeringKing Saud University

The structure,the morphology and the thermal,optical and the surface properties of nanocrystalline CeO_2 doped with mn have been studied by X-ray diffraction（XRD）,field-emission transmission electron microscopy（FE-TEm）,energy-dispersive X-ray analysis,thermogravimetric analysis,UV–Vis absorption spectroscopy and Fourier transform infrared *** XRD results confirmed the successful incorporation of mn into the CeO_2 lattice through the formation of nanoscale face-centered cubic solid *** FE-TEm observations supported the nanocrystalline nature of the solid *** presence of structural defects and their role on the band gap have been discussed on the basis of absorption spectral *** structural differences correlate with results from temperature-programmed reaction（TPR）experiments with H_2 *** TPR measurements showed an enhanced bulk reduction at much lower temperatures,indicating increased oxygen mobility in the samples,which enable to enhanced oxygen diffusion at lower temperatures.

关键词： Cerium oxide nanoparticle manganese Band gap energy Redox property

Carriers-assisted Enhanced Ferromagnetism in AI-doped ZnmnO Nano-crystallites

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Chinese Journal of Chemical Physics 2013年第4期26卷 457-461,J0002页

作者： shahid Atiqa Saadat A. Siddiqi Fazal Abbas murtaza Saleem shahid m.ramay 巴基斯坦旁遮普邦大学奎德-E-阿扎姆分校固态物理研究中心拉合尔54590 巴基斯坦COmSATS信息技术研究院生物医学材料交叉学科研究中心拉合尔沙特阿拉伯国王大学工程学院化学工程系利雅得114211

Zn0.95-zAlxmn0.050 （x=0, 0.03, 0.05, and 0.07） dilute magnetic semiconductor materials have been synthesized by sol-gel auto-combustion technique. The effect of A1 doping on the structural, electrical, and magnetic properties has been investigated. X-ray diffraction studies demonstrate the existence of single phase characteristic hexagonal wurtzite type crystal structure, similar to the host ZnO, in all the synthesized compositions. Although, the microscopic images revealed that the grains were clustered, yet some individual grains could be seen to have hexagonal texture. Electrical resistivity was observed to decrease with the rise of temperature up to 450 ℃, depicting the characteristic semiconductor behavior. Room temperature ferromagnetic behavior was observed in all the compositions. The value of saturation magnetization increased with the increase of A1 concentration in ZnmnO system referred to the gradual enhancement of free carriers.

关键词： Diluted magnetic semiconductor Al-doped ZnmnO Sol-gel Ferromagnetism

Vanadium based XVO3 (X=Na, K, Rb) as promising thermoelectric materials: First-principle DFT calculations

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Chinese Physics B 2020年第9期29卷 443-449页

作者： N A Noor Nosheen mushahid Aslam Khan Nessrin AKattan Asif mahmood shahid mramay Department of Physics University of LahoreLahore 54000Pakistan Physics Department KFUEITRahim Yar KhanPunjabPakistan Department of Physics Faculty of ScienceTaibah UniversityMedinaSaudi Arabia College of Engineering Chemical Engineering DepartmentKing Saud University RiyadhRiyadh 11451Saudi Arabia Department of Physics and Astronomy College of ScienceKing Saud University RiyadhRiyadh 11451Saudi Arabia

We investigate structural,mechanical,thermodynamic,and thermoelectric properties of vanadium-based XVO3(X=Na,K,Rb)materials using density functional theory(DFT)based *** structural and thermodynamic stabilities are probed by the tolerance factor(0.98,1.01,and 1.02)with the negative value of enthalpy of *** properties are analyzed in the form of Born stability criteria,ductile/brittle nature(Poisson and Pugh's ratios)and anisotropy *** explore the electronic transport properties,we study the electrical conductivity,thermal conductivity,Seebeck coefficient and power factor in terms of chemical potential and *** values of Seebeck coefficient at room temperature may find the potential of the studied perovskites in thermo-electrics devices.

关键词： density functional theory Born stability criteria Seebeck coefficient power factor

mg and Ni Incorporated ZnO Diluted magnetic Semiconductor for magnetic and Photo-Catalytic Applications

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Chinese Journal of Chemical Physics 2020年第6期33卷 743-748,I0003页

作者： Tahir Iqbal m.Irfan shahid m.ramay Abdullah Alhamidi Hamid Shaikh murtaza Saleem Saadat A.Siddiqi Department of Physics Mirpur University of Science and TechnologyMirpur 10250 AJKPakistan Physics and Astronomy Department College of ScienceKing Saud UniversityRiyadhSaudi Arabia SABIC Polymer Research Center Chemical Engineering DepartmentKing Saud UniversityP.O.Box 800Riyadh 11421Saudi Arabia School of Science and Engineering Lahore University of Management SciencesLahore 54792Pakistan IRCBm COMSATS University IslamabadLahore CampusLahore-54600Pakistan

Zinc oxide is recently being used as a magnetic semiconductor with the introduction of mag-netic *** this work,we report phase pure synthesis of mg and Ni co-substituted ZnO to explore its structure,optical,magnetic and photo-catalytic properties.X-ray di raction analysis reveals the hexagonal wurtzite type structure having P63mc space group without any impurity ***-Vis spectrophotometry demonstrates the variation in bandgap with the addition of mg and Ni content in ZnO *** measurements exhibit a clear boosted magnetization in Ni and mg co-doped compositions with its stable value of bandgap corroborating the structural stability and magnetic tuning for its advanced applications in modern-day spintronic ***-catalytic measurements performed using methyl green degradation demonstrate an enhanced trend of activity in mg and Ni co-doped compositions.

关键词： Dilute magnetic semiconductors X-ray di raction UV-Vis spectrophotometry magnetic properties Photo-catalysis

铝掺杂ZnmnO纳米晶体的载流子调控铁磁性（英文）

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Chinese Journal of Chemical Physics 2013年第4期 457-461+494页

作者： shahid Atiq Saadat A.Siddiqi Fazal Abbas murtaza Saleem shahid m.ramay 巴基斯坦旁遮普邦大学奎德-E-阿扎姆分校固态物理研究中心巴基斯坦COmSATS信息技术研究院生物医学材科交叉学科研究中心沙特阿拉伯国王大学工程学院化学工程系

通过溶胶-凝胶自燃烧技术合成了Zn0.95-xAlxmn0.05O（x=0、0.03、0.05和0.07）稀磁半导体材料.并且研究了Al掺杂对Zn0.95-xAlxmn0.05O结构、电学和磁学性质的效果.X射线衍射显示合成的组合物为单相六方晶系纤锌矿型晶体结构,类似于氧化... 详细信息

通过溶胶-凝胶自燃烧技术合成了Zn0.95-xAlxmn0.05O（x=0、0.03、0.05和0.07）稀磁半导体材料.并且研究了Al掺杂对Zn0.95-xAlxmn0.05O结构、电学和磁学性质的效果.X射线衍射显示合成的组合物为单相六方晶系纤锌矿型晶体结构,类似于氧化锌.显微图像显示颗粒呈团簇状,但一些单个颗粒呈现六角形纹理.观察到的电阻率随温度升高（达450℃）而降低,显示为半导体行为特征.所有组合物具有室温铁磁行为.饱和磁化强度的值随着Al（载流子）浓度的增加而增加.

关键词：稀磁半导体材料溶胶-凝胶 Al掺杂ZnmnO 铁磁性

Theoretical investigation of optical properties and band gap engineering for Zn1-xTmxTe(Tm=Fe,Co)alloys by modified Becke-Johnson potential

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Chinese Physics B 2017年第8期26卷 491-498页

作者： Q mahmood m Yaseen m Hassan shahid m.ramay Asif mahmood materials Growth and Simulation Laboratory Department of PhysicsUniversity of the PunjabQuaid-i-Azam Campus54590LahorePakistan Department Of Physlcs University of Agriculture UniversityFaisalabad 38040Pakistan Physics and Astronomy Department College of ScienceKing Sand UniversityRiyadhSaudi Arabia Chemical Engineering Department College of EngineeringKing Saud UniversityRiyadhSaudi Arabia

The direct band gap ZnTe with transition metal （Tm） impurities plays a vital role in optoelectronic and spintronic applications. In the present study, we use the advanced modified Becke-Johnson （mBJ） functional for performing the structural computations and detailed investigations of the optical characters in Zn1_xTmxTe （Tm = Fe, Co） alloys with 0 ≤ x ≤1. By employing the FP-LAPW method, we determine various optical parameters for the ternary alloys and for the end binaries. The calculated static dielectric constants and optical band gaps for Zn1_xTmxTe （Tm = Fe, Co） have an inverse relation that verifies the Penn model. We find that the static dielectric constant is nearly equal to the square of the static refractive index, and both increase with Tm content. Furthermore, we also find a slight shift of peaks to a higher energy region with increasing Tm concentration. The decreasing band gap and high value of the absorption in the visible region of electromagnetic spectrum make these alloys suitable for photonic and solar cell applications.

关键词： amorphous semiconductors transition metal-doped ZnTe structural computation optical property

Ab-initio calculations of bandgap tuning of In1-xGaxY(Y=N,P)alloys for optoelectronic applications

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Chinese Physics B 2021年第11期30卷 467-474页

作者： muhammad Rashid Jamil m mahmood Q shahid m.ramay Asif mahmood A Ghaithan H m Department of Physics Ghazi University City CampusDera Ghazi Khan32200Pakistan Department of Physics COMSATS University IslamabadIslamabad 44000Pakistan Basic and Applied Scientific Research Center(BASRC) College of Science of DammamImam Abdulrahman Bin Faisal UniversityP.O.Box 383Dammam 31113Saudi Arabia Department Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam 31441Saudi Arabia Physics and Astronomy Department College of ScienceKing Saud UniversityRiyadhSaudi Arabia Chemical Engineering Department College of EngineeringKing Saud UniversityRiyadhSaudi Arabia

The III–V alloys and doping to tune the bandgap for solar cells and other optoelectronic devices has remained a hot topic of research for the last few *** the present article,the bandgap tuning and its influence on optical properties of In1-xGaxN/P,where(x=0.0,0.25,0.50,0.75,and 1.0)alloys are comprehensively analyzed by density functional theory based on full-potential linearized augmented plane wave method(FP-LAPW)and modified Becke and Johnson potentials(TB-mBJ).The direct bandgaps turn from 0.7 eV to 3.44 eV,and 1.41 eV to 2.32 eV for In1-xGaxN/P alloys,which increases their potentials for optoelectronic *** optical properties are discussed such as dielectric constants,refraction,absorption,optical conductivity,and *** light is polarized in the low energy region with minimum *** absorption and optical conduction are maxima in the visible region,and they are shifted into the ultraviolet region by Ga ***,static dielectric constant e1(0)is in line with the bandgap from Penn’s model.

关键词： density functional theory direct bandgap III-V semiconductors tuning of optical band gap solar cell applications

magnetism,optical,and thermoelectric response of CdFe_2O_4by using DFT scheme

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Chinese Physics B 2018年第3期27卷 376-383页

作者： Q mahmood m Yaseen K C Bhamu Asif mahmood Y Javed shahid m.ramay materials Growth and Simulation Laboratory Department of PhysicsUniversity of the Punjab Department of Physics University of AgricultureFaisalabad Department of Physics Goa University Chemical Engineering Department College of Engineering King Saud University Physics and Astronomy Department College of Science King Saud University

Comparative analysis of electronic, magnetic, optical, and thermoelectric properties of CdFe2O4, calculated by em- ploying PBEsol ＋ mBJ has been done. The PBEsol reveals metallic nature, while TB-mBJ illustrates ferromagnetic semiconducting behavior. The reasons behind the origin of ferromagnetism are explored by observing the exchange, crystal field, and John-Teller energies. The optical nature is investigated by analyzing dielectric constants, refraction, absorption coefficient, reflectivity, and optical conductivity. Finally, thermoelectric properties are elaborated by describing the electri- cal and thermal conductivities, Seebeck coefficient, and power factor. The strong absorption for the visible energy and high power factor suggest CdFe2O4 as the potential candidate for renewable energy applications.

关键词： frustrated magnetism density functional theory John-Teller distortion Hund's rule