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Impact of La^(3+)substitution on electrical,magnetic,dielectric and optical properties of Ni_(0.7)Cu_(0.1)Zn_(0.2)LaxFe_(2-x)O_(4)(0

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Journal of Rare Earths 2023年第5期41卷 740-746,I0004页

作者： B.B.Patil A.D.Pawar S.S.Barate J.S.Ghodake J.B.Thorat T.J.Shinde P.G.Department of Physics Smt.KRP Kanya MahavidyalayaIslampurMS415409India Department of Physics Shivaji UniversityKolhapurMS416004India Departments of Physics PDVP MahavidyalayaMahavidyalayaTasgaonMS416312India Department of Physics Sadguru Gadage Maharaj CollegeKaradMS415110

The oxalate co-precipitation method was used to synthesize the La3+substituted Ni-Cu-Zn(La-NCZ)nanoferrites having chemical composition Ni_(0.7)Cu_(0.1)Zn_(0.2)LaxFe_(2-x)O_(4)(x=0.015,0.025 and 0.035).DC resistivity study of nanoferrites shows both the conducting and semiconducting *** room temperature DC electrical resistivity of Ni-Cu-Zn(NCZ)nanoferrites decreases,whereas Curie temperature increases with increasing La^(3+)*** the temperature range of 30-170℃nanoferrites show p-type semiconducting behavior except x=0.015;thereafter,they show n-type *** frequency dispersive initial permeability(μi)associated with its real and imaginary(μ’andμ")parts are attributed to the domain wall movement and magnetic spin ***μi,u’andμ"of La-NCZ nanoferrites are higher than those of pure NCZ *** constant(ε’),dielectric loss(ε")and AC resistivity(ρAC)of La-NCZ nanoferrites show normal dielectric *** is found thatε’of NCZ nanoferrites decreases with the increasing content of La3+*** bandgap energy of La-NCZ nanoferrites is achieved in the range 1.36-1.70 eV confirming the semiconducting nature of materials.

关键词： Ni-Cu-La-Zn nanoferrites DC electrical Resistivity Permeability Dielectric properties bandgap energy Rare earths

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Preparation of cerium and yttrium doped ZnO nanoparticles and tracking their structural,optical,and photocatalytic performances

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Journal of Rare Earths 2023年第5期41卷 682-688,I0002页

作者： Essia Hannachi Yassine Slimani Muhammad Nawaz R.Sivakumar Zayneb Trabelsi R.Vignesh Sultan Akhtar Munirah A.Almessiere Abdulhadi Baykal Ghulam Yasin Department of Nuclear Medicine Research Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Department of Biophysics Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityP.O.Box 1982Dammam31441Saudi Arabia Department of Nanomedicine Research Institute for Research and Medical Consultations(IRMC)Imam Abdulrahman Bin Faisal UniversityPO.Box 1982Dammam31441Saudi Arabia Department of Physics Alagappa UniversityKaraikudi630003India Faculty of Sciences of Bizerte University of CarthageZarzouna7021Tunisi Department of Physics College of ScienceImam Abdulrahman Bin Faisal UniversityP0.Box 1982Dammam31441Saudi Arabia State Key Laboratory of Chemical Resource Engineering College of Materials Science and EngineeringBeijing University of Chemical TechnologyBejing 100029China Institute for Advanced Study College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

Yttrium(Y)and cerium(Ce)co-doped ZnO nanoparticles(NPs)were synthesized via the simple sol-gel auto-combustion *** effect of Ce and Y doping on the structure,morphology,optical,Zeta potential,and photocatalytic activities of ZnO NPs was examined by Fourier transform infrared(FTIR)spectrometer,X-ray diffraction(XRD),transmission electron microscope(TEM),UV-vis spectrophotometer,and Zetasizer *** data show that the fabricated samples crystallize into a hexagonal wurtzite *** dopants Y and Ce affect the crystal structure of ZnO *** crystallite size is reduced with the co-doping *** results confirm the nano-sized particles of the prepared *** increase in optical bandgap values from 3.19 eV for x=0.0 to 3.22,3.24,and 3.25 eV for x=0.01,0.03,and 0.05 samples was confirmed by UV-Vis spectroscopy analysis.Y and Ce co-doped ZnO nanoparticles show significant alteration of zeta potential and photocatalytic properties compared to undoped ZnO ***,undoped ZnO shows better stability in deionized water as compared to Ce-Y doped ZnO NPs and exhibits high photocatalytic activity(degradation rate,97.92%)for methyl orange(MO)degradation.

关键词： ZnO nanoparticles Co-doping Rare earth Structure bandgap energy Photocatalytic activity

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Evidence for structural phase transitions and large effective band gaps in quasi-metallic ultra-clean suspended carbon nanotubes

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Nano Research 2013年第10期6卷 736-744页

作者： Shun-Wen Chang Rohan Dhall Moh Amer Kentaro Sato Riichiro Saito Stephen Cronin Department of Physics and Astronomy University of Southern California Los Angeles CA 90089 USA Department of Electrical Engineering University of Southern California Los Angeles CA 90089 USA Department of Chemistry University of Southern California Los Angeles CA 90089 USA Department of Physics Tohoku University Sendai 980-8578 Japan

We report evidence for a structural phase transition in individual suspended metallic carbon nanotubes by examining their Raman spectra and electron trans- port under electrostatic gate potentials. The current-gate voltage characteristics reveal anomalously large quasi-metallic band gaps as high as 240 meV, the largest reported to date. For nanotubes with band gaps larger than 200 meV, we observe a pronounced M-shape profile in the gate dependence of the 2D band （or G＇ band） Raman frequency. The pronounced dip （or softening） of the phonon mode near zero gate voltage can be attributed to a structural phase transition （SPT） that occurs at the charge neutrality point （CNP）. The 2D band Raman intensity also changes abruptly near the CNP, providing further evidence for a change in the lattice symmetry and a possible SPT. Pronounced non-adiabatic effects are observed in the gate dependence of the G band Raman mode, however, this behavior deviates from non-adiabatic theory near the CNP. For nanotubes with band gaps larger than 200 meV, non-adiabatic effects should be largely suppressed, which is not observed experimentally. This data suggests that these large effective band gaps are primarily caused by a SPT to an insulating state, which causes the large modulation observed in the conductance around the CNP. Possible mechanisms for this SPT are discussed, including electron-electron （e.g., Mott） and electron-phonon （e.g., Peierls） driven transitions.

关键词： carbon nanotube Raman spectroscopy phase transition bandgap energy

Role of the bandgaps on Some Interfacial Phenomena with Ionocovalent Oxides

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Rare Metals 1992年第2期11卷 81-85页

作者：李建国 Technische

Many ionocovalent oxide materials are either semiconducting or insulating in *** of the most im- portant quantities characterising these materials,therefore,is the bandgap *** thermodynamic ap- proaches to the bandgaps of oxides are briefly described and some interracial phenomena with oxides are pres- *** standard electrode potentials of oxide electrodes and the heterogeneous catalytic behaviours of the oxides as well as the wetting and adhesion in liquid metal/oxide systems can be closely related to the bandgap energies of the *** interfacial phenomena involving the ionocovalent oxides are associated with the electronic processes.

关键词： bandgap energy Interfacial phenomena Ionocovalent oxides Wetting Adhesion

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