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Phase transformation from cubic ZnS to hexagonal ZnO by thermal annealing

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Journal of Semiconductors 2015年第3期36卷 19-22页

作者： K.mahmood m.Asghar N.Amin Adnan Ali department of physics GC University Faisalabad department of physics The Islamia University of Bahawalpur

We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high- temperature thermal annealing. the ZnS thin films were grown on Si （001） substrate by thermal evaporation system using ZnS powder as source material. the grown films were annealed at different temperatures and characterized by X-ray diffraction （XRD）, photoluminescence （PL）, four-point probe, scanning electron microscope （SEm） and energy dispersive X-ray diffraction （EDX）. the results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. the observed result can be explained as a two- step process：（1） high-energy O atoms replaced S atoms in lattice during annealing process, and （2） S atoms diffused into substrate and/or diffused out of the sample. the dissociation energy of ZnS calculated from the Arrhenius plot of 1000/t versus log （resistivity） was found to be 3.1 eV. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 eV of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 eV and 2.5 eV respectively. SEm and EDX measurements were additionally performed to strengthen the argument.

关键词： ZnS phase transformation EDX XRD PL

Directional solidification and physical properties measurements of the zinc-aluminum eutectic alloy

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International Journal of minerals,metallurgy and materials 2011年第6期18卷 659-664页

作者： S.Engin U.Byük H.Kaya N.maraslι department of physics Institute of Science and TechnologyErciyes University department of Science Education Faculty of EducationErciyes University department of physics Faculty of ScienceErciyes University

Zn-5wt% Al eutectic alloy was directionally solidified with different growth rates （5.32-250.0μm/s） at a constant temperature gradient of 8.50 K/mm using a Bridgman-type growth *** values of eutectic spacing were measured from transverse sections of the *** dependences of the eutectic spacing and undercooling on growth rate are determined as λ=9.21V-0.53 and Δt=0.0245V0.53,*** results obtained in this work were compared with the Jackson-Hunt eutectic theory and the similar experimental results in the *** of directionally solidified samples was also measured by using a microhardness test *** dependency of the microhardness on growth rate is found as Hv=***,the electrical resistivity （r） of the casting alloy changes from 40×10-9 to 108×10-9 Ω·m with the temperature rising in the range of 300-630 *** enthalpy of fusion （ΔH） and specific heat （Cp） for the Zn-Al eutectic alloy are calculated to be 113.37 J/g and 0.309 J/（g·K）,respectively by means of differential scanning calorimetry （DSC） from heating trace during the transformation from liquid to solid.

关键词： eutectic alloys directional solidification microhardness electrical conductivity enthalpy specific heat

Variation in the Flaring Potential of Different Sunspot Groups During Different Phases of Solar Cycles 23 and 24

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Research in Astronomy and Astrophysics 2024年第2期24卷 144-153页

作者： Abha Singh Anurag Chaudhari Gyaneshwar Sharma A.K.Singh department of physics T.D.P.G.College Jaunpur-222002India department of physics Banaras Hindu UniversityVaranasi-221005India

In this present study,we have analyzed different types of X-ray solar flares(C,m,and X classes)coming out from different classes of sunspot groups(SSGs).the data which we have taken under this study cover the duration of 24 yr from 1996 to *** this,we observed a total of 15015 flares(8417 in SC-23 and 6598 in SC-24)emitted from a total of 33780 active regions(21746 in SC-23 and 12034 in SC-24)with sunspot *** defined the flaring potential or flare-production potential as the ratio of the total number of flares produced from a particular type of SSG to the total number of the same-class SSGs observed on the solar *** we studied yearly changes in the flaring potential of different mcIntosh class groups of sunspots in different phases of SC-23 and *** addition,we investigated yearly variations in the potential of producing flares by different SSGs(A,B,C,D,E,F,and H)during different phases(ascending,maximum,descending,and minimum)of SC-23 and *** are our findings:(1)D,E,and F SSGs have the potential of producing flares≥8 times greater than A,B,C and H SSGs;(2)the larger and more complex D,E,and F SSGs produced nearly 80%of flares in SC-23 and 24;(3)the A,B,C and H SSGs,which are smaller and simpler,produced only 20%of flares in SC-23 and 24;(4)the biggest and most complex SSGs of F-class have flaring potential 1.996 and 3.443 per SSG in SC-23 and 24,respectively.(5)the potential for producing flares in each SSG is higher in SC-24 than in SC-23,although SC-24 is a weaker cycle than SC-23.(6)the alterations in the number of flares(C+m+X)show different time profiles than the alterations in sunspot numbers during SC-23 and 24,with several peaks.(7)the SSGs of C,D,E,and H-class have the highest flaring potential in the descending phase of both SC-23 and 24.(8)F-class SSGs have the highest flaring potential in the descending phase of SC-23 but also in the maximum phase of SC-24.

关键词： (Sun:)sunspots-Sun flares-Sun activity-Sun magnetic fields-Sun filaments-prominences

DEFPOS and Its First Results

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Chinese Journal of Astronomy and Astrophysics 2005年第2期5卷 211-220页

作者： m.■ahan .Ye■ingil N.Aksaker .Kιzιo■lu m.Akyιlmaz department of physics Cukurova university 01330AdanaTurkeyDepartment of Physics Cukurova University01330AdanaTurkey Department of Physics Cukurova University01330AdanaTurkeyDepartment of Physics Middle East Technical UniversityAnkaraTurkeyDepartment of Physics Cukurova University01330AdanaTurkey

A spectrometer was built to examine the interstellar medium (ISm) using the hydrogen Balmer α line. It is called Dual Etalon Fabry-Perot Optical Spectrometer (DEFPOS). DEFPOS will be coupled to coudé exit of the 150 cm telescope (Rtt150) installed at tüBItAK National Observatory (tUG). DEFPOS was ready for observations about two years ago, but work was still continuing on the Rtt150 coudé exit alignment. So we have started observing HII regions with DEFPOS without the Rtt150. We present here some characteristics of the instrument and some of the results obtained.

关键词： ISm: general ISm: HII regions instrumentation: Interferometers techniques:interferometric atmospheric effect

Effect of Nd^(3+) substitution on structural and magnetic properties of mg-Cd ferrites synthesized by microwave sintering technique

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Journal of Rare Earths 2018年第4期36卷 390-397页

作者： S.R.Bhongale H.R.Ingawale t.J.Shinde P.N.Vasambekar department of physics Yashavantrao Chavan Institute of Science department of physics B.V.M.B.S.K.Kanya Mahvidyalaya department of physics K.R.P.Kanya Mahvidyalaya department of Electronics Shivaji University

Nd3＋ substituted spinel ferrites with formula mgxCd1-xNd0.03Fe1.97O4（x = 0.0.2,0.4,0.***.0.8 and 1.0）were prepared by oxalate co-precipitation method using novel microwave sintering technique. AR grade sulphates were used as starting chemicals. the samples were sintered at optimized power of 70 W for10 min in a microwave oven（800 W）. the structural analysis of these samples was done by using X-ray diffraction, scanning electron microscope and Fourier transform IR techniques. the XRD analysis of the synthesized ferrite confirms the formation of cubic spinel structure of ferrite. the influence of Nd3＋substitution on various structural parameters of mg-Cd ferrites was reported. IR study indicates the spectra contain two intense absorption bands around 600 and 400 cm^（-1） in addition with four extra bands. the magnetic properties of all ferrites were studied by using a vibration sample *** crystallite and grain size dependant magnetic properties are observed. the composition mg_（0.6）Cd_（0.4）Nd_（0.03）Fe_（1.97）O_4 has better magnetic properties that can be used in recording media. the fast synthesis of spinel ferrites is yielded due to use of the microwave sintering technique.

关键词： mg-Nd-Cd ferrite Rare earth microwave sintering IR study Coercive force

A computational investigation of topological insulator Bi2Se3 film

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Frontiers of physics 2014年第6期9卷 760-767页

作者： Yi-Bin Hu Yong-Hong Zhao Xue-Feng Wang department of physics MeGill University 3600 rue University Montrdal Qudbec H3A 2T8 Canada College of physics and Electronic Engineering Institute of Solid State Physics Sichuan Normal University Chengdu 610068 China department of physics Soochow University Suzhou 215006 China

topological insulators have a bulk band gap like a.n ordinary insulator and conducting states on their edge or surface which are formed by spin orbit coupling and protected by time-reversal sylnmetry. W＇e report theoretical analyses of tile electronic properties of three-dimensional topological insulator Bi2Sea film on different energies. We choose five different energies （ 123, -75, 0, 180. 350 meV） around the Dirac cone （ 113 meV）. When energy is close to the Dirac cone. the properties of wave function Inatch the topological insulator＇s halhnark perfectly. When energy is far way from tile Dirac cone, the halhnark of topological insulator is broken and the helical states disappear. the electronic properties of helical states are dug out fi＇om the calculation results. the spin-inomentum locking of the helical StatES are confirmed. A 3-fold symmetry of the helical states in Brillouin zone is also revealed. the penetration depth of tile helical states is two quintuple layers which can be identified from layer projection. tile charge contribution on each quintuple layer depends on the energy, and has completely different behavior along K and m direction in Brillouin zone. From orbital projection, we can find that the maximum charge contribution of the helical states is p： orbit and the charge contribution on py and Px orbits have 2-fold symmetry.

关键词： topological insulator spin-orbit coupling helical state

Origin of Dynamically Generated Baryon Rsonances

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原子核物理评论 2009年第S1期26卷 1-6页

作者： t.Hyodo D.Jido A.Hosaka Physik-department Technische Universitt Mnchen Yukawa Institute for theoretical physics Kyoto University Research Center for Nuclear physics(RCNP)

We study the origin of baryon resonances which are dynamically generated in the chiral unitary approach. We propose a natural renormalization scheme for the dynamical generation of resonances using the low energy chiral interaction and a general feature of the scattering theory. A deviation of a phenomenological scattering amplitude from the natural one is interpreted by an effective pole term interaction of genuine nature which can not be described by the meson-baryon dynamics,reminiscent of the CDD pole. Applying the present method to physical meson-baryon scatterings,we find that the Λ(1405) resonance is dominated by a meson-baryon component forming a KN-πΣ molecular-like structure,while the N(1535) resonance requires some pole contribution.

关键词： baryon resonances dynamical generation chiral unitary approach

Electromagnetic transition properties and isospin excitation in the cross-conjugate nuclei ^(44)ti and ^(52)Fe

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Chinese physics C 2010年第12期34卷 1823-1829页

作者：张进富吕立君白洪波 department of physics Chifeng University

the interacting boson model with isospin （IBm-3） is applied to study the band structure and electromagnetic transition properties of the low-lying states in the cross-conjugate nuclei 44ti and S2Fe. the isospin excitation states with t=0, 1 and 2 are identified and compared with available data. the E2 and m1 matrix elements for the low-lying states have been investigated. According to this study, the 2＋3 state is the lowest mixed symmetry state in the cross-conjugate nuclei 44ti and 52Fe. the excitation energy of the second 0＋2 and 2＋2 states with t=0 in the nucleus 52Fe are identified. the agreement between the model calculations and data is reasonably good.

关键词： spectrum isospin matrix element mixed symmetry states

time-Dependent Cylindrical and Spherical Solitary Structures and Double Layers of Dust Ion-Acoustic Waves in Ultra-Relativistic Dense Plasma

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Communications in theoretical physics 2013年第6期59卷 745-750页

作者： t.Akhter m.m.Hossain A.A.mamun department of physics Jahangirnagar University

Cylindrical and spherical (nonplanar) solitary waves (SWs) and double layers (DLs) in a multi-ion plasma system (containing inertial positively as well as negatively charged ions, non-inertial degenerate electrons, and negatively charged static dust) are studied by employing the standard reductive perturbation method. the modified Gardner (mG) equation describing the nonlinear propagation of the dust ion-acoustic (DIA) waves is derived, and its nonplanar SWs and DLs solutions are numerically analyzed. the parametric regimes for the existence of SWs, which are associated with both positive and negative potential, and DLs which are associated with negative potential, are obtained. the basic features of nonplanar DIA SWs, and DLs, which are found to be different from planar ones, are also identified.

关键词： solitary waves double layers ultra-relativistic dense plasma dust ion acoustic waves Gardnerequation