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Sample records for fe doped zno

  1. Photoluminescence quenching and enhanced spin relaxation in Fe doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ovhal, Manoj M.; Santhosh Kumar, A. [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India); Khullar, Prerna [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India); Kumar, Manjeet [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India); Abhyankar, A.C., E-mail: ashutoshabhyankar@gmail.com [Department of Materials Engineering, Defence Institute of Advanced Technology, Girinagar, Pune 411025 (India)

    2017-07-01

    Cost-effective ultrasonically assisted precipitation method is utilized to synthesize Zinc oxide (ZnO) nanoparticles (NPs) at room temperature and the effect of Iron (Fe) doping on structural, optical and spin relaxation properties also presented. As-synthesized pure and Fe doped ZnO NPs possess a perfect hexagonal growth habit of wurtzite zinc oxide, along the (101) direction of preference. With Fe doping, ‘c/a’ ratio and compressive lattice strain in ZnO NPs are found to reduce and increase, respectively. Raman studies demonstrate that the E{sub 1} longitudinal optical (LO) vibrational mode is very weak in pure which remarkably enhanced with Fe doping into ZnO NPs. The direct band gap energy (E{sub g}) of the ZnO NPs has been increased from 3.02 eV to 3.11 eV with Fe doping. A slight red-shift observed with strong green emission band, in photoluminescence spectra, is strongly quenched in 6 wt.% Fe doped ZnO NPs. The field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) reveals spherical shape of ZnO NPs with 60–70 nm, which reduces substantially on Fe doping. The energy dispersive X-ray spectrum and elemental mapping confirms the homogeneous distribution of Fe in ZnO NPs. Moreover, the specific relaxation rate (R{sub 2sp} = 1/T{sub 2}) has been measured using Carr-Purcell-Meiboom-Gill (CPMG) method and found to be maximum in 6 wt.% Fe doped ZnO NPs. Further, the correlation of structural, optical and dynamic properties is proposed. - Highlights: • Pure ZnO and Fe doped ZnO NPs were successfully prepared by cost effective ultrasonically assisted precipitation method. • The optical band gap of ZnO has been enhanced form 3.02–3.11 eV with Fe doping. • PL quenching behaviour has been observed with Fe{sup 3+} ions substitution in ZnO lattice. • Specific relaxation rate (R{sub 2sp} = 1/T{sub 2}) has been varied with Fe doping and found to be maximum in 6 wt.% Fe doped ZnO NPs.

  2. Synthesis of Fe Doped ZnO Nanowire Arrays that Detect Formaldehyde Gas.

    Science.gov (United States)

    Jeon, Yoo Sang; Seo, Hyo Won; Kim, Su Hyo; Kim, Young Keun

    2016-05-01

    Owing to their chemical and thermal stability and doping effects on providing electrons to the conduction band, doped ZnO nanowires have generated interest for use in electronic devices. Here we report hydrothermally grown Fe-doped ZnO nanowires and their gas-sensing properties. The synthesized nanowires have a high crystallinity and are 60 nm in diameter and 1.7 μm in length. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) are employed to understand the doping effects on the microstructures and gas sensing properties. When the Fe-doped ZnO nanowire arrays were evaluated for gas sensing, responses were recorded through changes in temperature and gas concentration. Gas sensors consisting of ZnO nanowires doped with 3-5 at.% Fe showed optimum formaldehyde (HCHO) sensing performance at each working temperature.

  3. Preparation and characterization of ZnO and Fe-doped ZnO films by sol-gel method

    OpenAIRE

    Zhang, Xin; Wang,Jiangang; Ma, Jing; Hu, Jianwen

    2016-01-01

    ZnO and Fe-doped ZnO thin films are prepared on glass substrate by sol-gel method, and the surface morphology, structure and optical property are analyzed by scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD) and UV-Vis-NIR spectrophotometer. The results show that both films have a smooth surface and a hexagonal wurtzite structure with orienting along the (101) plane. Compared with the ZnO film, the surface of Fe-doped ZnO film becomes smoother, and its...

  4. Structural, optical and electronic properties of Fe doped ZnO thin films

    Science.gov (United States)

    Singh, Karmvir; Devi, Vanita; Dhar, Rakesh; Mohan, Devendra

    2015-09-01

    Fe doped ZnO thin films have been deposited by pulsed laser deposition technique on quartz substrate to study structural, optical and electronic structure using XRD, AFM, UV-visible and X-ray absorption spectroscopy. XRD study reveals that Fe doping has considerable effect on stress, strain, grain size and crystallinity of thin films. UV-visible study determines that band gap of pristine ZnO decreases with Fe doping, which can be directly correlated to transition tail width and grain size. Change in electronic structure with Fe doping has been examined by XAS study.

  5. First principles study of magneto-optical properties of Fe-doped ZnO

    Science.gov (United States)

    Shaoqiang, Guo; Qingyu, Hou; Zhenchao, Xu; Chunwang, Zhao

    2016-12-01

    Studies on optical band gaps and absorption spectra of Fe-doped ZnO have conflicting conclusions, such as contradictory redshifted and blueshifted spectra. To solve this contradiction, we constructed models of un-doped and Fe-doped ZnO using first-principles theory and optimized the geometry of the three models. Electronic structures and absorption spectra were also calculated using the GGA+U method. Higher doping content of Fe resulted in larger volume of doped system, and higher total energy resulted in lower stability. Higher formation energy also led to more difficult doping. Meanwhile, the band gaps broadened and the absorption spectra exhibited an evident blue shift. The calculations were in good agreement with the experimental results. Given the unipolar structure of ZnO, four possible magnetic coupling configurations for Zn14Fe2O16 were calculated to investigate the magnetic properties. Results suggest that Fe doping can improve ferromagnetism in the ZnO system and that ferromagnetic stabilization was mediated by p-d exchange interaction between Fe-3d and O-2p orbitals. Therefore, the doped system is expected to obtain high stability and high Curie temperature of diluted magnetic semiconductor material, which are useful as theoretical bases for the design and preparation of the Fe-doped ZnO system's magneto-optical properties.

  6. Doping concentration driven morphological evolution of Fe doped ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, A.; Goswami, N., E-mail: navendugoswami@gmail.com [Department of Physics and Materials Science and Engineering, Jaypee Institute of Information Technology, A-10, Sector-62, Noida-201307 (India); Kumar, Y.; Agarwal, V. [CIICAp-UAEM, Av. Universidad 1001, Col Chamilpa, Cuernavaca 62209 (Mexico); Olive-Méndez, S. F. [Centro de Investigación en Materiales Avanzados, S. C., CIMAV, Av. Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Chihuahua 31109 (Mexico)

    2014-10-28

    In this paper, systematic study of structural, vibrational, and optical properties of undoped and 1-10 at.% Fe doped ZnO nanostructures, synthesized adopting chemical precipitation route, has been reported. Prepared nanostructures were characterized employing an assortment of microscopic and spectroscopic techniques, namely Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX) Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Micro-Raman Spectroscopy (μRS), and UV-visible and Photoluminescence (PL) spectroscopy. With Fe incorporation, a gradual morphological transformation of nanostructures is demonstrated vividly through SEM/TEM characterizations. Interestingly, the morphology of nanostructures evolves with 1–10 at. % Fe doping concentration in ZnO. Nanoparticles obtained with 1 at. % Fe evolve to nanorods for 3 at. % Fe; nanorods transform to nanocones (for 5 at. % and 7 at. % Fe) and finally nanocones transform to nanoflakes at 10 at. % Fe. However, at all these stages, concurrence of primary hexagonal phase of Zn{sub 1-x}Fe{sub x}O along with the secondary phases of cubic ZnFe{sub 2}O{sub 4} and rhombohedric Fe{sub 2}O{sub 3}, is revealed through XRD analysis. Based on collective XRD, SEM, TEM, and EDX interpretations, a model for morphological evolution of nanostructures was proposed and the pivotal role of Fe dopant was deciphered. Furthermore, vibrational properties analyzed through Raman and FTIR spectroscopies unravel the intricacies of formation and gradual enhancement of secondary phases with increased Fe concentration. UV-visible and PL spectroscopic analyses provided further insight of optical processes altering with Fe incorporation. The blue shift and gradual quenching of visible photoluminescence with Fe doping was found in accordance with structural and vibrational analyses and explicated accordingly.

  7. Photocatalytic Characterization of Fe- and Cu-Doped ZnO Nanorods Synthesized by Cohydrolysis

    Directory of Open Access Journals (Sweden)

    Young Rang Uhm

    2013-01-01

    Full Text Available Fe- and Cu-doped ZnO nanorods have been synthesized by a novel process employing a hydrolysis of metal powders. Zn, Fe, and Cu nanopowders were used as starting materials and incorporated into distilled water. The solution was refluxed at 60°C for 24 h to obtain the precipitates from the hydrolysis of Zn and dopants (Cu and Fe. The TEM results for ZnO with and without metal doping showed that the produced powders had a rod-like shape. The rod shape was attributable to the zinc oxide from the hydrolysis of Zn. With an increasing doping content, the UV-vis spectra were shifted to a long wavelength and this result indicates that the band gap was changed by the metal doping. The values of phenol degrading Fe- and Cu-doped ZnO by a solar simulator were measured to be 60 and 75%, respectively.

  8. Doping concentration driven morphological evolution of Fe doped ZnO nanostructures

    Science.gov (United States)

    Sahai, A.; Kumar, Y.; Agarwal, V.; Olive-Méndez, S. F.; Goswami, N.

    2014-10-01

    In this paper, systematic study of structural, vibrational, and optical properties of undoped and 1-10 at.% Fe doped ZnO nanostructures, synthesized adopting chemical precipitation route, has been reported. Prepared nanostructures were characterized employing an assortment of microscopic and spectroscopic techniques, namely Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX) Spectroscopy, X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Micro-Raman Spectroscopy (μRS), and UV-visible and Photoluminescence (PL) spectroscopy. With Fe incorporation, a gradual morphological transformation of nanostructures is demonstrated vividly through SEM/TEM characterizations. Interestingly, the morphology of nanostructures evolves with 1-10 at. % Fe doping concentration in ZnO. Nanoparticles obtained with 1 at. % Fe evolve to nanorods for 3 at. % Fe; nanorods transform to nanocones (for 5 at. % and 7 at. % Fe) and finally nanocones transform to nanoflakes at 10 at. % Fe. However, at all these stages, concurrence of primary hexagonal phase of Zn1-xFexO along with the secondary phases of cubic ZnFe2O4 and rhombohedric Fe2O3, is revealed through XRD analysis. Based on collective XRD, SEM, TEM, and EDX interpretations, a model for morphological evolution of nanostructures was proposed and the pivotal role of Fe dopant was deciphered. Furthermore, vibrational properties analyzed through Raman and FTIR spectroscopies unravel the intricacies of formation and gradual enhancement of secondary phases with increased Fe concentration. UV-visible and PL spectroscopic analyses provided further insight of optical processes altering with Fe incorporation. The blue shift and gradual quenching of visible photoluminescence with Fe doping was found in accordance with structural and vibrational analyses and explicated accordingly.

  9. Raman scattering and photoluminescence of Fe-doped ZnO nanocantilever arrays

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bin; ZHOU ShaoMin; WANG HaiWei; DU ZuLiang

    2008-01-01

    Single crystalline Fe-doped ZnO nanocantilever arrays have been synthesized by thermal evaporating amorphous Zn-Fe-C-O composite powder. The characterizations of composition, structure and phonon spectrum properties of the nanocantilevers have been performed. Arrays of uniform, perfectly aligned and single-crystal nanowires have been observed by electron microscopy. The results of the X-ray photo-electric spectra and the Raman spectrum provide the evidence that Fe is incorporated into the ZnO lattice at Zn site. Abnormally, the room temperature UV emission band of Fe-doped ZnO nanocantilevers disappears and the green one has a large red-shift, and the intensity of the green emission is strongly quenched because the Fe3+ enters the ZnO crystal lattice.

  10. Electronic Structure and Optical Properties of Co and Fe doped ZnO

    Directory of Open Access Journals (Sweden)

    Li Chunping

    2016-01-01

    Full Text Available First-principle ultrasoft pseudo potential approach of the plane wave based on density functional theory has been used for studying the electronic characterization and optical properties of ZnO and Fe, Co doped ZnO. The results show that the doping impurities change the lattice parameters a little, but bring more changes in the electronic structures. The band gaps are broadened by doping. And the Fermi level accesses to the conduction band which will lead the system to show the character of metallic properties. The dielectric function and absorption peaks are identified and the changes compared to pure ZnO are analyzed in detail.

  11. First principles study of magneto-optical properties of Fe-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Shaoqiang, Guo [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); Qingyu, Hou, E-mail: by0501119@126.com [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); Zhenchao, Xu [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); Chunwang, Zhao [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); College of Arts and Sciences, Shanghai Maritime University, Shanghai 201306 (China)

    2016-12-15

    Studies on optical band gaps and absorption spectra of Fe-doped ZnO have conflicting conclusions, such as contradictory redshifted and blueshifted spectra. To solve this contradiction, we constructed models of un-doped and Fe-doped ZnO using first-principles theory and optimized the geometry of the three models. Electronic structures and absorption spectra were also calculated using the GGA+U method. Higher doping content of Fe resulted in larger volume of doped system, and higher total energy resulted in lower stability. Higher formation energy also led to more difficult doping. Meanwhile, the band gaps broadened and the absorption spectra exhibited an evident blue shift. The calculations were in good agreement with the experimental results. Given the unipolar structure of ZnO, four possible magnetic coupling configurations for Zn{sub 14}Fe{sub 2}O{sub 16} were calculated to investigate the magnetic properties. Results suggest that Fe doping can improve ferromagnetism in the ZnO system and that ferromagnetic stabilization was mediated by p–d exchange interaction between Fe-3d and O-2p orbitals. Therefore, the doped system is expected to obtain high stability and high Curie temperature of diluted magnetic semiconductor material, which are useful as theoretical bases for the design and preparation of the Fe-doped ZnO system’s magneto-optical properties. - Highlights: • A biomonitoring tool for the freshwater zone of template estuaries. • Water quality characterization related to nutrients and organic matter enrichment. • The percentage of a group of 24 tolerant species were capable of detecting the impairment of the water quality. • Characterization of morpho-functional traits of the selected tolerant species.

  12. Ferromagnetic behaviour of Fe-doped ZnO nanograined films

    Directory of Open Access Journals (Sweden)

    Boris B. Straumal

    2013-06-01

    Full Text Available The influence of the grain boundary (GB specific area sGB on the appearance of ferromagnetism in Fe-doped ZnO has been analysed. A review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area sGB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if sGB is higher than a certain threshold value sth = 5 × 104 m2/m3. It corresponds to the effective grain size of about 40 μm assuming a full, dense material and equiaxial grains. Magnetic properties of ZnO dense nanograined thin films doped with iron (0 to 40 atom % have been investigated. The films were deposited by using the wet chemistry “liquid ceramics” method. The samples demonstrate ferromagnetic behaviour with Js up to 0.10 emu/g (0.025 μB/f.u.ZnO and coercivity Hc ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe content can be explained by the changes in the structure and contiguity of a ferromagnetic “grain boundary foam” responsible for the magnetic properties of pure and doped ZnO.

  13. Ferromagnetic behaviour of Fe-doped ZnO nanograined films.

    Science.gov (United States)

    Straumal, Boris B; Protasova, Svetlana G; Mazilkin, Andrei A; Tietze, Thomas; Goering, Eberhard; Schütz, Gisela; Straumal, Petr B; Baretzky, Brigitte

    2013-01-01

    The influence of the grain boundary (GB) specific area s GB on the appearance of ferromagnetism in Fe-doped ZnO has been analysed. A review of numerous research contributions from the literature on the origin of the ferromagnetic behaviour of Fe-doped ZnO is given. An empirical correlation has been found that the value of the specific grain boundary area s GB is the main factor controlling such behaviour. The Fe-doped ZnO becomes ferromagnetic only if it contains enough GBs, i.e., if s GB is higher than a certain threshold value s th = 5 × 10(4) m(2)/m(3). It corresponds to the effective grain size of about 40 μm assuming a full, dense material and equiaxial grains. Magnetic properties of ZnO dense nanograined thin films doped with iron (0 to 40 atom %) have been investigated. The films were deposited by using the wet chemistry "liquid ceramics" method. The samples demonstrate ferromagnetic behaviour with J s up to 0.10 emu/g (0.025 μB/f.u.ZnO) and coercivity H c ≈ 0.03 T. Saturation magnetisation depends nonmonotonically on the Fe concentration. The dependence on Fe content can be explained by the changes in the structure and contiguity of a ferromagnetic "grain boundary foam" responsible for the magnetic properties of pure and doped ZnO.

  14. First-Principles Study of Fe-Doped ZnO Nanowires

    Institute of Scientific and Technical Information of China (English)

    张富春; 张威虎; 董军堂; 张志勇

    2011-01-01

    Using Srst-principles theory, we predict magnetic, electronic and optical properties in Fe-doped ZnO nanowires. The results show that ferromagnetic (FM) coupling of configuration V is the most stable, and the strong hybridization effect between FeZd and O2p states is found near the Fermi level, and it is obvious that the ferromagnetic system is electron-spin polarization of 100% and half-metallic. Given antiferromagnetic (AFM) coupling, the system generates small spin polarization near the Fermi level, indicating metalh'city. The magnetic moments mainly arise from FeZd orbitals. In addition, the results of optical properties show that the Fe-doped ZnO nanowires have apparent absorption peaks in the ultraviolet band and that there is a small red shift and a strong blue shift in the near and far ultraviolet band, indicating that Fe-doped ZnO nanowires are a type of magneto-optical materials with great promise.%Using first-principles theory,we predict magnetic,electronic and optical properties in Fe-doped ZnO nanowires.The results show that ferromagnetic(FM)coupling of configuration V is the most stable,and the strong hybridization effect between Fe3d and O2p states is found near the Fermi level,and it is obvious that the ferromagnetic system is electron-spin polarization of 100% and half-metallic.Given antiferromagnetic(AFM)coupling,the system generates small spin polarization near the Fermi level,indicating metallicity.The magnetic moments mainly arise from Fe3d orbitals.In addition,the results of optical properties show that the Fe-doped ZnO nanowires have apparent absorption peaks in the ultraviolet band and that there is a small red shift and a strong blue shift in the near and far ultraviolet band,indicating that Fe-doped ZnO nanowires are a type of magneto-optical materials with great promise.

  15. Evidence of a cluster glass-like behavior in Fe-doped ZnO nanoparticles

    Science.gov (United States)

    Ramos, J. E.; Montero-Muñoz, M.; Coaquira, J. A. H.; Rodríguez-Páez, J. E.

    2014-05-01

    We report on the study of the structural and magnetic properties of crystalline Fe-doped ZnO nanoparticles with Fe content up to 10% synthesized by a co-precipitation method. The Rietveld analysis indicates that the Fe-doped ZnO nanoparticles are formed in a single phase wurtzite structure. DC magnetization (M) vs. applied magnetic field (H) curves obtained at 5 K show the occurrence of a ferromagnetic behavior. The coercive field and saturation magnetization depend on the Fe content. At room temperature, M vs. H curves show features consistent with a superparamagnetic state of nanoscale system. The temperature dependence of the AC and DC magnetic susceptibilities show features related to the thermal relaxation of the nano-sized particles. From the AC data analysis, a magnetic transition from the superparamagnetic to cluster-glass state is determined.

  16. Structural, elemental, optical and magnetic study of Fe doped ZnO and impurity phase formation

    Institute of Scientific and Technical Information of China (English)

    S.Karamat; R.S. Rawat; P. Lee; T.L. Tan; R.V. Ramanujan

    2014-01-01

    We have prepared a series of (ZnO)1-x(Fe2O3)x r 0.10 bulk samples with various concentrations of Fe dopant by ball milling and investigated their structural, compositional, optical and magnetic properties by means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectrometer and vibrating sample magnetometer (VSM), respectively. Information about different impurity phases was obtained through Rietveld refinements of XRD data analysis. XPS results showed different valence states (Fe2 þ and Fe3 þ ) supported by shaking satellite peaks in samples. With increasing Fe doping percentage, the crystal quality deteriorated and a shift of E2 low band (characteristic of ZnO) has been observed in Raman spectra. Energy band gap estimated from reflectance UV–vis spectroscopy showed shift for all bulk samples. The magnetic behavior was examined using a vibrating sample magnetometer (VSM), indicating ferromagnetic behavior at room temperature (300 K). The effective magnetic moment per Fe atom decreases with increase in doping percentage which indicates that ferromagnetic behavior arises from the substitution of Fe ions in the ZnO lattice.

  17. Synthesis and characterization of ball milled Fe-doped ZnO diluted magnetic semiconductor

    Institute of Scientific and Technical Information of China (English)

    R. Elilarassi; G. Chandrasekaran

    2012-01-01

    Fe-doped ZnO (Zn0.99Fe0.01O) powders are successfully prepared by ball milling with different milling time,and are investigated using X-ray diffraction (XRD),scanning electron microscope (SEM),ultraviolet-visible (UV-VIS) spectroscopy,vibrating sample magnetometer (VSM) and electron paramagnetic resonance (EPR) spectroscopy.The structural analysis using XRD reveals that the Fe-doped ZnO milled at different milling time can crystallize in a wurtzite structure,and in the XRD patterns,the secondary phase related to Fe cluster with the sensitivity of the XRD instrument can not be found.The SEM image of the sample milled for 24 h shows the presence of spherical nanoparticles.From the optical analysis,the optical band gap is found to decrease with increasing the milling time,which indicates the incorporation of Fe2+ ions into the ZnO lattice.The magnetization measurement using VSM reveals that the nanoparticles exhibit ferromagnetic behavior at room temperature,and the magnetization increases gradually with increasing the milling time.The conclusion is further confirmed by the electron paramagnetic resonance of the nanoparticles examined at room temperature,which shows an intense and broad ferromagnetic resonance signal related to Fe ions.

  18. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Santosh, E-mail: skphysics@yahoo.co.in [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Deepika [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Tripathi, Malvika [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Vaibhav, Pratyush [Jaypee University of Engineering and Technology, Guna 473226, Madhya Pradesh (India); Kumar, Aman [Indian Institute of Technology, Roorkee (India); Kumar, Ritesh [Department of Physics, College of Commerce, Arts & Science, Patna 800020, Bihar (India); Choudhary, R.J., E-mail: ram@csr.res.in [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India); Phase, D.M. [UGC DAE, Consortium for scientific research, Indore 452001, Madhya Pradesh (India)

    2016-12-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn{sub 0.97}Al{sub 0.03}O, Zn{sub 0.95}Fe{sub 0.05}O and Zn{sub 0.92}Al{sub 0.03}Fe{sub 0.05}O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments. - Highlights: • Al, Fe, Al–Fe co-doped and undoped films of ZnO are deposited on Si by PLD. • Single phase (002) oriented Wurtzite ZnO phase is formed for all films. • Fe doped and Fe–Al co-doped ZnO films reveal magnetic hysteresis at 300 K. • Negative magnetoresistance is observed in undoped and Fe–Al co-doped ZnO film. • It is apparent that charge carriers are coupled with the local magnetic moment.

  19. Optical and sensing properties of Fe doped ZnO nanocrystalline thin films

    Directory of Open Access Journals (Sweden)

    Shukla R.K.

    2016-06-01

    Full Text Available Undoped and Fe doped ZnO films of different molarities deposited by spray pyrolysis method using zinc nitrate and ferric chloride as precursors show polycrystalline nature and hexagonal wurtzite structure. Crystallite size decreases with an increase in dopant concentration from 0 at.% to 3 at.%. Doping improves the transmission of the films whereas it reduces the optical band gap of ZnO from 3.28 eV to 3.17 eV. The morphology resembles flake-like structures which collapse when the dopant is introduced. The samples are found to be sensitive to CO2 gas. Undoped ZnO shows maximum sensitivity at 350 °C for higher concentration of CO2. Doped samples show maximum sensitivity at 200 °C for all CO2 concentrations i.e. from 500 ppm to 4000 ppm. Maximum sensitivity is achieved at temperatures 350 °C, 250 °C, 300 °C and 450 °C for the samples prepared using precursor solution of 0.1 M molarity.

  20. The influence of Fe doping on the structural, magnetic and optical properties of nanocrystalline ZnO particles

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, Rosari, E-mail: rosari.saleh@ui.ac.id [Departemen Fisika, Fakultas MIPA-Universitas Indonesia, 16424 Depok (Indonesia); Prakoso, Suhendro Purbo [Departemen Fisika, Fakultas MIPA-Universitas Indonesia, 16424 Depok (Indonesia); Fishli, Adel [PTBIN-BATAN, Kawasan PUSPITEK Serpong (Indonesia)

    2012-03-15

    We report the results of an investigation of Fe-doped nanocrystalline ZnO particles synthesized using the co-precipitation method with doping concentrations from 5 up to 31 at%. To understand how the dopant influenced the structural, magnetic and optical properties of nanocrystalline ZnO particles, X-ray diffraction, energy dispersive X-ray spectroscopy, infrared absorption spectroscopy, UV-vis spectroscopy, electron spin resonance spectroscopy (ESR) and vibrating sample magnetometer were employed. From the analysis of X-ray diffraction, our Fe-doped nanocrystalline ZnO particles are identified as having the wurtzite crystal structure and the unit cell volume increases with increasing doping concentrations. However, impurity phases are observed for Fe contents higher than 21 at%. Sample structures were further studied by infrared spectra, from which a broad and strong absorption band in the range of 400-700 cm{sup -1} and -OH stretching vibrational mode at approximately 3400 cm{sup -1} were observed. Ultraviolet-visible measurements showed a decrease in the energy gap with increasing Fe content, probably due to an increase in the lattice parameters. Magnetic measurements showed a ferromagnetic behavior for all samples. ESR results indicate the presence of Fe in both valence states Fe{sup 2+} and Fe{sup 3+}. - Highlights: Black-Right-Pointing-Pointer Fe-doped ZnO nanoparticles (Fe content {<=}31 at%) were prepared by co-precipitation. Black-Right-Pointing-Pointer All samples exhibited room temperature ferromagnetism. Black-Right-Pointing-Pointer Magnetization increased with increasing doping concentrations. Black-Right-Pointing-Pointer ESR results indicate the presence of Fe in both valence states Fe{sup 2+} and Fe{sup 3+}. Black-Right-Pointing-Pointer These results are consistent with the result obtained from VSM measurements.

  1. UV light photocatalytic degradation of organic dyes with Fe-doped ZnO nanoparticles

    Science.gov (United States)

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-10-01

    Iron doped wurtzite ZnO nanoparticles were synthesized and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, UV-Vis diffuse reflectance spectroscopy, electron spin resonance and vibrating sample magnetometer techniques. The photocatalytic activities were also evaluated for the degradation of methyl orange and methylene blue under UV irradiation. The effects of various parameters, such as pH, dopant concentrations and photocatalytic dosage, were studied. The ESR results indicate the presence of Fe in both the Fe2+ and Fe3+ valence states. As the dopant concentrations increased, the number of spins due to Fe2+ ions increased and the number of spins due to Fe3+ ions decreased resulting in an increase in magnetization. The catalysts with the highest number of spins due to Fe2+ ions exhibited the optimum photocatalytic activity for the degradation of methyl orange and methylene blue. In addition, the role of photoactive species was investigated using a radical scavenger technique. The results indicated that the doping concentration is the most important factor in photocatalytic performance.

  2. Fe-doped ZnO Supported with Montmorillonite: Synthesis, Characterization, and Photocatalytic Activity

    Science.gov (United States)

    Pratiwi, M. I.; Afifah, N.; Saleh, R.

    2017-05-01

    In this study, Fe-doped ZnO/MMT has been prepared by using co-precipitation method with the various amount of MMT (10, 20, 30, and 40 wt%). The samples were characterized by using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy, and (FTIR), Brunauer-Emmett-Teller (BET) surface area analysis. The crystallite structure of ZnO did not change with the additional of dopant and MMT. The presence of MMT could be confirmed by using FTIR, which showed the bending vibration and stretching vibration of Si-O-Al and Si-O-Si. The degradation of methylene blue and methyl orange were examined by using montmorillonite (MMT) modified Fe-doped ZnO catalyst in photocatalytic process under UV light irradiation. The photocatalytic results indicated that certain amount of MMT could increase photocatalytic performance in degrading methylene blue and methyl orange. Methylene blue degradation increased with the increasing of pH value while the opposite trend occurred for methyl orange degradation.

  3. A Mössbauer and magnetic study of ball milled Fe-doped ZnO Powders

    Energy Technology Data Exchange (ETDEWEB)

    Zamora, Ligia E., E-mail: ligia.zamora@correounivalle.edu.co; Paz, J. C.; Piamba, J. F.; Tabares, J. A.; Alcázar, G. A. Pérez [Universidad del Valle, Departamento de física (Colombia)

    2015-06-15

    The structural and magnetic properties of Fe-doped ZnO are reported in this study, as obtained by mechanical alloying from elemental powders of ZnO and Fe. The properties of Zn{sub 0.90}Fe{sub 0.10}O samples alloying while varying the milling time (6, 12, 24 and 36 h) are also reported. The Rietveld refinement of X-ray Diffraction (XRD) patterns revealed that the system presents two structures: the würtzite structure of ZnO and the bcc structure of α-Fe. The Mössbauer spectra show that the samples present three components: a ferromagnetic component, associated with the Fe phase and two paramagnetic components, associated with the Fe atoms, which penetrate inside the ZnO matrix behaving as Fe{sup 3+} and Fe{sup 2+}. The milling time contributes to an increase in the paramagnetic sites, and a solubility limit of the Fe atoms in the ZnO lattice was detected. The VSM measurements at room temperature detected ferromagnetic behavior with a saturation magnetization of 11 emu/g and a coercive field of 330 Oe for the sample alloyed over 24 h. A similar behavior was shown by the other samples.

  4. Optical and Magnetic Properties of Fe Doped ZnO Nanoparticles Obtained by Hydrothermal Synthesis

    Directory of Open Access Journals (Sweden)

    Xiaojuan Wu

    2014-01-01

    Full Text Available Diluted magnetic semiconductors Zn1-xFexO nanoparticles with different doping concentration (x=0, 0.01, 0.05, 0.10, and 0.20 were successfully synthesized by hydrothermal method. The crystal structure, morphology, and optical and magnetic properties of the samples were characterized by X-ray diffraction (XRD, energy dispersive spectrometer (EDS, high-resolution transmission electron microscopy (HRTEM, Raman scattering spectra (Raman, photoluminescence spectra (PL, and the vibrating sample magnetometer (VSM. The experiment results show that all samples synthesized by this method possess hexagonal wurtzite crystal structure with good crystallization, no other impurity phases are observed, and the morphology of the sample shows the presence of ellipsoidal nanoparticles. All the Fe3+ successfully substituted for the lattice site of Zn2+ and generates single-phase Zn1-xFexO. Raman spectra shows that the peak shifts to higher frequency. PL spectra exhibit a slight blue shift and the UV emission is annihilated with the increase of Fe3+ concentration. Magnetic measurements indicated that Fe-doped ZnO samples exhibit ferromagnetic behavior at room temperature and the saturation magnetization is enhanced with the increase of iron doping content.

  5. Decoloration of organic dyes using zeolites supported Fe-doped ZnO under UV light irradiation

    Science.gov (United States)

    Pratiwi, M. I.; Afifah, N.; Saleh, R.

    2017-07-01

    Various weight percentages of natural zeolite (10 % - 40 %) had been coupled into Fe-doped ZnO (Fe:ZnO) nanoparticles using the co-precipitation method. The photocatalytic acivity of Fe:ZnO/Zeolites nanocomposites was monitored under UV light irradiation in decoloring methylene blue and methyl orange. The result shows that certain amount of natural zeolite in Fe:ZnO could increase the photocatalytic activity of the nanocomposites. The synthesized samples were characterized using some measurements such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and Brunauer-Emment-Tellet (BET) surface area analysis. The FTIR spectra of the samples show the existance of zeolites in the samples. XRD patterns show that no crystal structure changes in ZnO after doping with Fe and supported with zeolites.

  6. Investigation on structural and electrical properties of Fe doped ZnO nanoparticles synthesized by solution combustion method

    Science.gov (United States)

    Ram, Mast; Bala, Kanchan; Sharma, Hakikat; Kumar, Arun; Negi, N. S.

    2016-05-01

    In the present study, nanoparticles of Fe doped zinc oxide (ZnO) [Zn1-xFexO where x=0.0, 0.01, 0.02, 0.03 and 0.05] were prepared by cost effective solution combustion method. The powder X-ray diffractometry confirms the formation of single phase wurtzite structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the micrsostructure of Fe-doped ZnO nanoparticles. The DC electrical conductivity was found to increase with temperature and measurement was carried out in the temperature range of 300-473K. DC electrical conductivity increases with temperature and decreases with Fe doping concentration.

  7. Synthesis of Fe-Doped ZnO Nanorods by Rapid Mixing Hydrothermal Method and Its Application for High Performance UV Photodetector

    Directory of Open Access Journals (Sweden)

    Chan Oeurn Chey

    2014-01-01

    Full Text Available We have successfully synthesized Fe-doped ZnO nanorods by a new and simple method in which the adopted approach is by using ammonia as a continuous source of OH- for hydrolysis instead of hexamethylenetetramine (HMT. The energy dispersive X-ray (EDX spectra revealed that the Fe peaks were presented in the grown Fe-doped ZnO nanorods samples and the X-ray photoelectron spectroscopy (XPS results suggested that Fe3+ is incorporated into the ZnO lattice. Structural characterization indicated that the Fe-doped ZnO nanorods grow along the c-axis with a hexagonal wurtzite structure and have single crystalline nature without any secondary phases or clusters of FeO or Fe3O4 observed in the samples. The Fe-doped ZnO nanorods showed room temperature (300 K ferromagnetic magnetization versus field (M-H hysteresis and the magnetization increases from 2.5 μemu to 9.1 μemu for Zn0.99Fe0.01O and Zn0.95Fe0.05O, respectively. Moreover, the fabricated Au/Fe-doped ZnO Schottky diode based UV photodetector achieved 2.33 A/W of responsivity and 5 s of time response. Compared to other Au/ZnO nanorods Schottky devices, the presented responsivity is an improvement by a factor of 3.9.

  8. Electrical, dielectric and photocatalytic properties of Fe-doped ZnO nanomaterials synthesized by sol gel method

    Directory of Open Access Journals (Sweden)

    Yacine Cherif

    2016-09-01

    Full Text Available Fe-doped ZnO nanoparticles were synthesized by sol gel technique. Fine-scale and single phase hexagonal wurtzite structure in all samples were confirmed by SEM and XRD, respectively. The band gap energy depends on the amount of Fe and was found to be in the range of 3.11–2.53 eV. The electric and dielectric properties were investigated using complex impedance spectroscopy. AC conductivity data were correlated with the barrier hopping (CBH model to evaluate the binding energy (Wm, the minimum hopping distance (Rmin and the density of states at Fermi level, N(EF. Fe doping in ZnO also improved the photocatalytic activity. Thus, the sample Zn0.95Fe0.05O showed high degradation potential towards methylene blue (MB, i.e. it degrades 90% of BM in 90 min under UV light.

  9. Effect of Fe-doping on the structural, morphological and optical properties of ZnO nanoparticles synthesized by solution combustion process

    Science.gov (United States)

    Silambarasan, M.; Saravanan, S.; Soga, T.

    2015-07-01

    The effect of Fe-doping on the structural, morphological and optical properties of ZnO nanoparticles synthesized by simple solution combustion process are reported. The powder XRD pattern indicates that the Fe-doped ZnO samples exhibit primary and secondary phases. The primary phase indicates the hexagonal wurtzite structure with the average crystalline size of around 25-50 nm and the secondary phase is associated with the face centered cubic structure of magnetite iron oxide. The elemental composition of pure and Fe-doped samples are evaluvated by EDX. The results of FE-SEM and HR-TEM cleary show that particles morphology have changed with respect to the incorporation of doping agent and particles are in aggregating nature. The vibrational properties of the synthesized ZnO nanoparticles are investigated by Raman scattering technique and it exhibits that the influence of Fe-doping significantly modify the lattice vibrational characteristics in ZnO sites. The optical properties of the Fe-doped ZnO nanoparticles are carried out by UV-vis absorption and PL spectra. The results of PL spectra show the near-band edge related emission as well as strong blue emissions in the Fe-doped ZnO nanoparticles.

  10. Effect of Al and Fe doping in ZnO on magnetic and magneto-transport properties

    Science.gov (United States)

    Kumar, Santosh; Deepika; Tripathi, Malvika; Vaibhav, Pratyush; Kumar, Aman; Kumar, Ritesh; Choudhary, R. J.; Phase, D. M.

    2016-12-01

    The structural, magnetic and magneto-transport of undoped ZnO, Zn0.97Al0.03O, Zn0.95Fe0.05O and Zn0.92Al0.03Fe0.05O thin films grown on Si(100) substrate using pulsed laser deposition were investigated. The single phase nature of the films is confirmed by X-ray diffraction and Raman spectroscopy measurements. The possibility of Fe metal cluster in Fe doped/co-doped films is ruled out by Fe 2p core level photoelectron spectra. From O 1s core level spectra it is observed that oxygen vacancy is present in all the films. The undoped ZnO film shows magnetic ordering below ∼175 K, whereas Fe doped/codoped samples show magnetic ordering even at 300 K. The Al doped sample reveals paramagnetic behavior. The magneto-transport measurements suggest that the mobile carriers undergo exchange interaction with local magnetic moments.

  11. Photocatalytic degradation of organic dyes by Er3+: YAlO3/Co- and Fe-doped ZnO coated composites under solar irradiation

    Science.gov (United States)

    Chen, Yang; Lu, Chunxiao; Tang, Liang; Song, Yahui; Wei, Shengnan; Rong, Yang; Zhang, Zhaohong; Wang, Jun

    2016-12-01

    In this work, the Er3+: YAlO3/Co- and Fe-doped ZnO coated composites were prepared by the sol-gel method. Then, they were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). Photo-degradation of azo fuchsine (AF) as a model dye under solar light irradiation was studied to evaluate the photocatalytic activity of the Er3+: YAlO3/Co- and Fe-doped ZnO coated composites. It was found that the photocatalytic activity of Co- and Fe-doped ZnO composites can be obviously enhanced by upconversion luminescence agent (Er3+: YAlO3). Besides, the photocatalytic activity of Er3+: YAlO3/Fe-doped ZnO is better than that of Er3+: YAlO3/Co-doped ZnO. The influence of experiment conditions, such as the concentration of Er3+: YAlO3, heat-treatment temperature and time on the photocatalytic activity of the Er3+: YAlO3/Co- and Fe-doped ZnO coated composites was studied. In addition, the effects of solar light irradiation time, dye initial concentration, Er3+: YAlO3/Co- and Fe-doped ZnO amount on the photocatalytic degradation of azo fuchsine in aqueous solution were investigated in detail. Simultaneously, some other organic dyes, such as Methyl Orange (MO), Rhodamine B (RM-B), Acid Red B (AR-B), Congo Red (CR), and Methyl Blue (MB) were also studied. The possible excitation principle of Er3+: YAlO3/Co- and Fe-doped ZnO coated composites under solar light irradiation and the photocatalytic degradation mechanism of organic dyes were discussed.

  12. Al and Fe co-doped transparent conducting ZnO thin film for mediator-less biosensing application

    Directory of Open Access Journals (Sweden)

    Shibu Saha

    2011-12-01

    Full Text Available Highly c-axis oriented Al and Fe co-doped ZnO (ZAF thin film is prepared by pulsed laser deposition. Fe introduces redox centre along with shallow donor level while Al doping enhances conductivity of ZnO, thus removing the requirement of both mediator and bottom conducting layer in bioelectrode. Model enzyme (glucose oxidase, was immobilized on surface of ZAF matrix. Cyclic voltammetry and photometric assay show that prepared bio-electrode is sensitive to glucose concentration with enhanced response of 0.18 μAmM-1cm-2 and low Km ∼ 2.01 mM. The results illustrate that ZAF is an attractive matrix for realization of miniaturized mediator-less solid state biosensor.

  13. Photocatalytic, optical and magnetic properties of Fe-doped ZnO nanoparticles prepared by chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Khanesh; Chitkara, Mansi; Sandhu, Inderjit Singh [Nanomaterials Research Laboratory (NRL), Department of Applied Sciences, Chitkara University, Rajpura 140401, Punjab (India); Mehta, D. [Department of Physics, Panjab University, Chandigarh 160014 (India); Kumar, Sanjeev, E-mail: sanjeevkumar@chitkara.edu.in [Department of Physics, G.G.D.S.D. College, Chandigarh 160030 (India)

    2014-03-05

    Highlights: • Zn{sub 1-x}Fe{sub x}O nanoparticles are synthesized using bottom-up wet chemical precipitation technique. • Photocatalytic activity was evaluated by monitoring the photodegradation of methylene blue dye. • Specific magnetization values of the synthesized materials are found to depend on Fe concentration. -- Abstract: Polyvinyl pyrrolidone (PVP) capped Zn{sub 1−x}Fe{sub x}O (0.000001 ⩽ x ⩽ 0.1) nanocrystalline powders were prepared by chemical co-precipitation technique. Structural, optical and magnetic characterizations of the annealed samples were performed using X-ray powder diffraction (XRD), transmission electron microscope (TEM), energy dispersive X-ray fluorescence (EDXRF), Fourier-transform infrared (FTIR) spectroscopy, UV–visible spectrophotometry, photoluminescence (PL) and vibrating sample magnetometer (VSM) measurements. XRD and TEM studies reveal that the synthesized ZnO nanocrystals have hexagonal wurtzite structure with average crystalline size ∼8–15 nm. EDXRF and FTIR measurements confirmed the doping and incorporation of Fe impurities in ZnO nanostructures. Photocatalytic efficiency of the synthesized samples was determined by degradation of methylene blue (MB) dye in aqueous solution under UV/sunlight exposure. The dependence of photocatalytic behavior and luminescence efficiency on the dopant concentration was studied in detail. Magnetic measurements performed at room temperature show that pure ZnO exhibits diamagnetic behavior, ferromagnetic order was clearly observed at minute concentration of Fe impurity (at 0.000010%) and large concentration of dopant (at 10%) leads to strong paramagnetic component in all the Fe-doped ZnO samples.

  14. Structural, optical, and magnetic properties of Fe-doped ZnO films prepared by spray pyrolysis method

    Energy Technology Data Exchange (ETDEWEB)

    Soumahoro, I. [Laboratoire de Physique des Materiaux, Faculte des Sciences, BP 1014, Rabat (Morocco); Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), UMR 7504 du CNRS, UDS-ECPM, BP 43, 23 Rue du Loess, 67034 Strasbourg Cedex 2 (France); Moubah, R.; Schmerber, G.; Colis, S. [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), UMR 7504 du CNRS, UDS-ECPM, BP 43, 23 Rue du Loess, 67034 Strasbourg Cedex 2 (France); Aouaj, M. Ait; Abd-lefdil, M.; Hassanain, N. [Laboratoire de Physique des Materiaux, Faculte des Sciences, BP 1014, Rabat (Morocco); Berrada, A., E-mail: alamal39@hotmail.f [Laboratoire de Physique des Materiaux, Faculte des Sciences, BP 1014, Rabat (Morocco); Dinia, A. [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS), UMR 7504 du CNRS, UDS-ECPM, BP 43, 23 Rue du Loess, 67034 Strasbourg Cedex 2 (France)

    2010-06-01

    Zn{sub 1-x}Fe{sub x}O thin films with different Fe content were deposited on glass substrates at 450 {sup o}C by spray pyrolysis technique. The effect of doping on the structural and optical properties of ZnO films was investigated. X-ray diffraction has shown that the films are polycrystalline and textured with the c-axis of the wurtzite structure along the growth direction. Scanning electron microscopy has shown that the surface of the films are homogeneous. The magnetic measurements performed at 5 K using a SQUID magnetometer showed the co-existence of paramagnetic, antiferromagnetic and ferromagnetic contributions.

  15. Morphological evolution and electronic alteration of ZnO nanomaterials induced by Ni/Fe co-doping.

    Science.gov (United States)

    Fletcher, Cameron; Jiang, Yijiao; Sun, Chenghua; Amal, Rose

    2014-07-07

    Zinc oxide (ZnO) nanocrystals mono- and co-doped with nickel/iron were prepared using a facile solvothermal procedure. A significant change in the surface morphology from nanorods to plate-like nanoparticles was observed with an increase in the dopant concentration. The variations of their optical and electronic properties induced by metal dopants were investigated using a combination of characterization techniques and ab initio calculations. It is found that both nickel and iron atoms have been successfully incorporated into the crystal lattice rather than forming a secondary phase, suggesting good dispersion of dopants within the ZnO matrix. Doping with iron has red-shifted the absorption edges of ZnO towards the visible portion resulting in lower band gap energies with increasing dopant concentration. Evidenced by Raman and EPR spectroscopy, the addition of iron has been shown to promote the formation of more oxygen vacancy and crystal defects within the host lattice as well as increasing the free-electron density of the nanomaterial. The DFT plus Hubbard model calculations confirm that low concentration Ni-doping does not induce band gap narrowing but results in localized states. The calculations show that Fe-doping has the potential to greatly improve the optical absorption characteristics and lead to structural deformation, corroborating the UV-Vis, Raman, and EPR spectra.

  16. ZnO nanoparticles co-doped with Fe3+ and Eu3+ ions for solar assisted photocatalysis.

    Science.gov (United States)

    Yin, Dongguang; Zhang, Le; Song, Kailin; Ou, Yangjuan; Wang, Chengcheng; Liu, Bing; Wu, Minghong

    2014-08-01

    In this study, ZnO nanoparticles co-doped with Fe3+ and Eu3+ were prepared by a facile co-precipitation method. The structure and morphology of the as-prepared nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and diffuse reflectance absorption spectra, respectively. The photocatalytic activities of the prepared catalysts were evaluated by photocatalytic degradation of methyl orange in aqueous solution with solar light irradiation. The co-doped Fe3+ and Eu3+ showed a synergistic effect, which significantly increased the photocatalytic activity of ZnO. The influences of calcination time, photocatalytic reaction temperature and catalyst loading on the photocatalytic activity of the catalyst were also investigated. It was found that there were an optimum photocatalytic reaction temperature and an optimum catalyst loading for high photocatalytic efficiency, and the photocatalytic efficiency decreased with increase in calcination time. The results of this study demonstrate that the as-prepared product of Eu3+/Fe3+/ZnO is a promising photocatalyst for solar assisted degradation of organic pollutions.

  17. Disinfection of Multidrug Resistant Escherichia coli by Solar-Photocatalysis using Fe-doped ZnO Nanoparticles.

    Science.gov (United States)

    Das, Sourav; Sinha, Sayantan; Das, Bhaskar; Jayabalan, R; Suar, Mrutyunjay; Mishra, Amrita; Tamhankar, Ashok J; Stålsby Lundborg, Cecilia; Tripathy, Suraj K

    2017-12-01

    Spread of antibiotic resistant bacteria through water, is a threat to global public health. Here, we report Fe-doped ZnO nanoparticles (Fe/ZnO NPs) based solar-photocatalytic disinfection (PCD) of multidrug resistant Escherichia coli (MDR E. coli). Fe/ZnO NPs were synthesized by chemical precipitation technique, and when used as photocatalyst for disinfection, proved to be more effective (time for complete disinfection = 90 min) than ZnO (150 min) and TiO2 (180 min). Lipid peroxidation and potassium (K(+)) ion leakage studies indicated compromisation of bacterial cell membrane and electron microscopy and live-dead staining confirmed the detrimental effects on membrane integrity. Investigations indicated that H2O2 was the key species involved in solar-PCD of MDR E. coli by Fe/ZnO NPs. X-ray diffraction and atomic absorption spectroscopy studies showed that the Fe/ZnO NPs system remained stable during the photocatalytic process. The Fe/ZnO NPs based solar-PCD process proved successful in the disinfection of MDR E. coli in real water samples collected from river, pond and municipal tap. The Fe/ZnO NPs catalyst made from low cost materials and with high efficacy under solar light may have potential for real world applications, to help reduce the spread of resistant bacteria.

  18. Effect of Fe doping on the microstructure and electrical properties of transparent ZnO nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Lin, C.C. [Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan, ROC (China); Young, S.L., E-mail: slyoung@mail.hust.edu.tw [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China); Kung, C.Y., E-mail: cykung@dragon.nchu.edu.tw [Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan, ROC (China); Jhang, M.C. [Department of Electrical Engineering, National Chung Hsing University, Taichung 40227, Taiwan, ROC (China); Lin, C.H. [Department and Graduate School of Electrical Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China); Kao, M.C.; Chen, H.Z. [Department of Electronic Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China); Ou, C.R.; Cheng, C.C.; Lin, H.H. [Department and Graduate School of Electrical Engineering, Hsiuping University of Science and Technology, Taichung 41280, Taiwan, ROC (China)

    2013-02-01

    The transparent ZnO and Zn{sub 0.96}Fe{sub 0.04}O nanocrystalline films were deposited on the glass substrates by sol–gel method followed by repaid thermal annealing treatment. The grain size of the ZnO films was decreased by the doping of Fe. X-ray diffraction measurements of the films showed the same wurtzite hexagonal structure and preferential orientation along the c-axis. Temperature dependence resistivity showed a semiconductor transport behavior for both compositions. At high temperature region, the transport mechanism can be fitted with semiconductor behavior by Arrhenius equation, σ(T) = σ{sub 0}exp[−(E{sub a}/kT){sup m}] with m = 1. The activation energy E{sub a} is increased from 0.47 meV for pure ZnO film to 0.69 meV for Zn{sub 0.96}Fe{sub 0.04}O film obtained from equation. At low temperature region, the resistivity can be fitted well with the behavior of Mott variable range hopping, σ(T) = σ{sub h0}exp[−(T{sub 0}/T){sup n}] with n = 1/4. The results demonstrate that the crystallization and the corresponding carrier transport behavior of the Zn{sub 1−x}Fe{sub x}O films are affected by the doping of Fe in the Zn{sub 1−x}Fe{sub x}O films.

  19. Improved Resistance Switching Stability in Fe-Doped ZnO Thin Films Through Pulsed Magnetic Field Annealing.

    Science.gov (United States)

    Xu, Hongtao; Wu, Changjin; Xiahou, Zhao; Jung, Ranju; Li, Ying; Liu, Chunli

    2017-12-01

    Five percent of Fe-doped ZnO (ZnO:Fe) thin films were deposited on Pt/TiO2/SiO2/Si substrates by a spin-coating method. The films were annealed without (ZnO:Fe-0T) and with a pulsed magnetic field of 4 T (ZnO:Fe-4TP) to investigate the magnetic annealing effect on the resistance switching (RS) behavior of the Pt/ZnO:Fe/Pt structures. Compared with the ZnO:Fe-0T film, the ZnO:Fe-4TP film showed improved RS performance regarding the stability of the set voltage and the resistance of the high resistance state. Transmission electron microscopy and X-ray photoelectron spectroscopy analyses revealed that the ZnO:Fe-4TP film contains more uniform grains and a higher density of oxygen vacancies, which promote the easier formation of conducting filaments along similar paths and the stability of switching parameters. These results suggest that external magnetic fields can be used to prepare magnetic oxide thin films with improved resistance switching performance for memory device applications.

  20. Effect of (Fe, Co) co-doping on the structural, electrical and magnetic properties of ZnO nanocrystals prepared by solution combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Ram, Mast, E-mail: mastram1999@yahoo.com; Negi, N.S.

    2016-01-15

    The structural, electrical and magnetic properties of Zn{sub 1−x}Co{sub 0.05}Fe{sub x}O (where, x=0, 1, 2, 3 and 5 mol%) nanoparticles prepared by solution combustion method are reported. The X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive analysis of X-rays (EDX) have been used for structural and compositional analysis. The X-ray diffraction pattern showed the existence of hexagonal wurtzite structure of parent ZnO with co-doping. The microstructural studies reveal the dense nanostructured morphology of these samples. The DC electrical conductivity measurements have been carried out in the temperature range of 300–450 K. The DC electrical conductivity decreases with the increasing Fe concentration. The magnetic studies reveal room temperature ferromagnetisation in doped ZnO nanoparticles. The magnetic properties of ZnO nanoparticles improve with increasing Fe dopant concentration.

  1. Structural, FTIR and photoluminescence studies of Fe doped ZnO nanopowder by co-precipitation method.

    Science.gov (United States)

    Raja, K; Ramesh, P S; Geetha, D

    2014-10-15

    An investigation on Fe-doped ZnO (Zn1-xFexO, x=0, 0.03, 0.06 and 0.09mM) nanopowder have been synthesized by co-precipitated method annealed at 550°C were reported. The structural, morphological and optical properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectra (EDS) analysis, Atomic Force Microscopy (AFM), UV-Visible spectroscopy, and photoluminescence (PL) techniques, Fourier transform infrared (FTIR) spectroscopy. The XRD spectrum shows all the samples are hexagonal wurtzite structure. The presence of functional groups and chemical bonding are confirmed by FT-IR. The PL spectra of the Zn1-xFexxO systems show that the shift in near band edge (NBE) UV emission from 344.54 to 364.21nm and a shift in green band (GB) emission from 484 to 540nm which conforms the substitution of Fe into the ZnO lattice. UV-Visible measurement showed a decrease in the energy gap with increasing Fe content, probably due to an increase in the lattice parameters. It is also found that these results are in good agreement with other calculated and experimental results.

  2. 水热合成Fe~(3+)掺杂ZnO复合材料及其光催化活性%Hydrothermal Synthesis and Photocatalytic Property of Fe~(3+)-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    刘英; 梁英

    2009-01-01

    以Zn(Ac)_2·2H_2O、Fe(NO_3)_3·9H_2O和NaOH为原料,采用水热法合成了Fe~(3+)掺杂ZnO复合材料. 并用X射线衍射和扫描电子显微镜测试技术对合成样品的结构和形貌进行了表征. 结果表明,Fe~(3+)掺杂ZnO合成产物为直棒状,直径为500 nm,长度为3 μm左右. 样品的紫外可见漫反射分析结果表明,在300~500 nm紫外可见光区域均有强的吸收. Fe~(3+)掺杂ZnO作为光催化剂降解有机染料性能优于纯ZnO材料.%With Zn(Ac)_2·2H_2O, Fe(NO_3)_3·9H_2O and NaOH as raw materials, Fe~(3+)-doped ZnO was prepared by hydrothermal method. The structure and morphology were investigated by means of X-ray diffrac-tion and scanning electron microscopy. The measurements indicated that the Fe~(3+)-doped ZnO was rod like. The UV diffuse reflectance absorbent properties were detected on a UV-Lambda35 spectrophotometer. The results showed that the Fe~(3+)-doped ZnO had strong absorption in UV and visible regions. Photodegradation of dyes in an aqueous solution was investigated with Fe~(3+)-doped ZnO as a photocatalyst. The results showed that Fe~(3+)-doped ZnO had better degradation properties than pure ZnO.

  3. Surfactant-Free Microwave-Assisted Synthesis of Fe-Doped ZnO Nanostars as Photocatalyst for Degradation of Tropaeolin O in Water under Visible Light

    Directory of Open Access Journals (Sweden)

    Tsz-Lung Kwong

    2015-01-01

    Full Text Available Iron-doped zinc oxide nanostar was synthesized by the microwave-assisted surfactant-free hydrolysis method. The as-synthesized Fe-doped ZnO nanostars catalyst was fully characterized by scanning electron microscope (SEM, transmission electron microscopy (TEM, energy dispersive X-ray spectroscopy (EDX, powder X-ray diffraction (XRD, and diffuse reflectance UV-vis spectroscopy (UV-DRA. The photocatalytic activity of the photocatalyst was investigated for the photocatalytic degradation of Tropaeolin O under visible light irradiation. It is observed that the doping of Fe ions enhances the absorption of the visible light and thus the photocatalytic degradation rate of Tropaeolin O would increase. Despite the Taguchi orthogonal experimental design method, the photocatalytic conversion could be achieved at 99.8% in the Fe-doped ZnO catalyzed photodegradation reaction under the optimal reaction conditions of catalyst loading (30 mg, temperature (60°C, light distance (0 cm, initial pH (pH = 9, and irradiation time (3 h. The Fe-doped ZnO photocatalyst can also be easily recovered and directly reused for eight cycles with over 70% conversion.

  4. Effect of size reduction on structural and optical properties of ZnO matrix due to successive doping of Fe ions

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, M. Mehedi [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002 (India); Khan, Wasi, E-mail: wasiamu@gmail.com [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002 (India); Azam, Ameer [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002 (India); Centre of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Naqvi, A.H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engineering and Technology, Aligarh Muslim University, Aligarh 202002 (India)

    2014-01-15

    In this work 0%, 3%, 5%, 7% and 10% Fe doped ZnO nanoparticles (NPs) have been successfully synthesized by the sol–gel method. The compositional, structural and optical studies have been investigated by XRD, FESEM equipped with EDS, TEM with SAED, UV–visible and Photoluminescence spectroscopy. XRD, SEM and TEM results confirmed the formation of nanoparticles with polycrystalline single phase nature with hexagonal wurtzite structure. The crystallite size has been found to vary between 10 and 20 nm with changes in the doping concentration of Fe. The stretching bonds in ZnO have been observed in FTIR spectra. The UV–visible and PL spectra show a red shift with increase of dopant concentration. The band gaps for all samples were calculated by the Tauc relation and narrowing of band gap from 3.33 eV to 3.26 eV with increasing Fe dopant concentration up to 10% was found. The band gap is narrowing because of the s–d and p–d exchange interactions which introduce a negative and a positive correction to the conduction and the valence-band edges respectively. -- Highlights: • We have synthesized Fe doped ZnO nanoparticles by low cost sol–gel method. • Grain size, lattice parameters and bond length of ZnO are found to decrease with increase of Fe concentration. • Particles size is found to decrease from 20 nm to 10 nm. • Crystallite size decreases optical band gap from 3.33 eV to 3.26 eV.

  5. The electronic, magnetic and optical properties of ZnO doped with doubles impurities (Cr, Fe): An LDA-SIC and Monte Carlo study

    Science.gov (United States)

    Salmani, El Mehdi; Laghrissi, Ayoub; Lamouri, Rachida; Ez-Zahraouy, Hamid; Benyoussef, Abdelilah

    2017-01-01

    Electronic structure, magnetic and optical properties of ZnO doped with single and double impurities Zn1-xCrxO, Zn1-xFexO, and Zn1-2xCrxFexO (x=0.03 and 0.06) are investigated using first-principles calculations. Based on the Korringa-Kohn-Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of doubles impurities (Cr, Fe) doped ZnO. To support our results, we apply the self-interaction-corrected local density approximation (SIC-LDA) to study the electronic structure, optical and magnetic properties of Co-doped ZnO with doubles impurities (Cr, Fe) showing that the half-metallic ferromagnetic state still persists. The stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing their total energies. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with high Neel temperature.

  6. Voltammetric Sensor Based on Fe-doped ZnO and TiO2 Nanostructures-modified Carbon-paste Electrode for Determination of Levodopa

    Science.gov (United States)

    Anaraki Firooz, Azam; Hosseini Nia, Bahram; Beheshtian, Javad; Ghalkhani, Masoumeh

    2017-10-01

    In this study, undoped and 1 wt.% Fe-doped with ZnO, and TiO2 nanostructures were synthesized by a simple hydrothermal method without using templates. The influence of the Fe dopant on structural, optical and electrochemical response was studied by x-ray diffraction, scanning electron microscopy, UV-Vis spectra, photoluminescence spectra and electrochemical characterization system. The electrochemical response of the carbon paste electrode modified with synthesized nanostructures (undoped ZnO and TiO2 as well as doped with Fe ions) toward levodopa (L-Dopa) was studied. Cyclic voltammetry using provided modified electrodes showed electro-catalytic properties for electro-oxidation of L-Dopa and a significant reduction was observed in the anodic overvoltage compared to the bare electrode. The results indicated the presence of the sufficient dopants. The best response was obtained in terms of the current enhancement, overvoltage reduction, and reversibility improvement of the L-Dopa oxidation reaction under experimental conditions by the modified electrode with TiO2 nanoparticles doped with Fe ions.

  7. Microstructure and conduction behavior of BiFeO3 thin film deposited on Ge-doped ZnO

    Science.gov (United States)

    Raghavan, Chinnambedu Murugesan; Choi, Ji Ya; Kim, Sang Su

    2017-02-01

    BiFeO3 (BFO) thin films were deposited on a Ge-doped ZnO (GZO)/Si(100) and a Pt(111)/Ti/SiO2/Si(100) using a pulsed laser deposition technique. An improved crystal growth property was observed for the BFO thin film deposited on the GZO/Si(100). The BFO thin film, which was deposited on the (00 l) textured GZO/Si(100), exhibited preferred ( l00) orientated grains, while randomly orientated grains were observed for the thin film deposited on the Pt(111)/Ti/SiO2/Si(100). When compared with the Pt/BFO/Pt capacitor, the GZO/BFO/GZO capacitor exhibited improved conduction behaviors, such as a low leakage current density and high stability against electrical breakdown. From the J-E curves, conduction of the GZO/BFO/GZO and the Pt/BFO/Pt capacitors was found to be dominated by Ohmic and space charge limited conductions at low and high electric field, respectively.

  8. Investigation of structural, surface morphological, optical properties and first-principles study on electronic and magnetic properties of (Ce, Fe)-co doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Arul Mary, J. [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry Loyola College, Chennai 600 034 (India); Judith Vijaya, J., E-mail: jjvijayaloyola@yahoo.co.in [Catalysis and Nanomaterials Research Laboratory, Department of Chemistry Loyola College, Chennai 600 034 (India); Bououdina, M. [Departments of Physics, College of Science, University of Bahrain, PO Box 32038 Kingdom of Bahrain (Bahrain); John Kennedy, L. [Materials Division, School of Advanced Sciences, Vellore Institute of Technology (VIT) University, Chennai Campus, Chennai 600 127 (India); Daie, J.H.; Song, Y. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, 2 West Wenhua Road, Weiahi 264209 (China)

    2015-01-01

    We report on the synthesis of ((Zn{sub 1−2x}Ce{sub x}Fe{sub x}) O (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05)) nanoparticles via microwave combustion by using urea as a fuel. To understand how the dopant influenced the structural, magnetic and optical properties of nanoparticles, it was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM). The stability and magnetic properties of Ce and Fe co-doped ZnO were probed by first principle calculations. From the analysis of X-ray diffraction, the samples are identified with the wurtzite crystal structure. The change in lattice parameters, micro-strain, and a small shift in XRD peaks confirms the substitution of co dopants into the ZnO lattice. Morphological investigation of the products revealed the existence of irregular shapes, such as spherical, spherodial and hexagonal. DRS measurements showed a decrease in the energy gap with increasing dopants contents, probably due to an increase in the lattice parameters. PL spectra consist of visible emission, due to the electronic defects, which are related to deep level emissions, such as oxide antisite (O{sub Zn}), interstitial zinc (Zn{sub i}), interstitial oxygen (O{sub i}) and zinc vacancy (V{sub Zn}). Magnetic measurements showed a ferromagnetic behavior for all the doped samples at room temperature. The first principle calculation results showed that the Ce governs the stability, while the Fe adjusts the magnetic characteristics in the Ce and Fe co-doped ZnO.

  9. Investigation of structural, surface morphological, optical properties and first-principles study on electronic and magnetic properties of (Ce, Fe)-co doped ZnO

    Science.gov (United States)

    Arul Mary, J.; Judith Vijaya, J.; Bououdina, M.; John Kennedy, L.; Daie, J. H.; Song, Y.

    2015-01-01

    We report on the synthesis of ((Zn1-2xCexFex) O (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05)) nanoparticles via microwave combustion by using urea as a fuel. To understand how the dopant influenced the structural, magnetic and optical properties of nanoparticles, it was characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectra and vibrating sample magnetometer (VSM). The stability and magnetic properties of Ce and Fe co-doped ZnO were probed by first principle calculations. From the analysis of X-ray diffraction, the samples are identified with the wurtzite crystal structure. The change in lattice parameters, micro-strain, and a small shift in XRD peaks confirms the substitution of co dopants into the ZnO lattice. Morphological investigation of the products revealed the existence of irregular shapes, such as spherical, spherodial and hexagonal. DRS measurements showed a decrease in the energy gap with increasing dopants contents, probably due to an increase in the lattice parameters. PL spectra consist of visible emission, due to the electronic defects, which are related to deep level emissions, such as oxide antisite (OZn), interstitial zinc (Zni), interstitial oxygen (Oi) and zinc vacancy (VZn). Magnetic measurements showed a ferromagnetic behavior for all the doped samples at room temperature. The first principle calculation results showed that the Ce governs the stability, while the Fe adjusts the magnetic characteristics in the Ce and Fe co-doped ZnO.

  10. Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations

    Indian Academy of Sciences (India)

    A El Amiri; H Lassri; M Abid; E K Hlil

    2014-06-01

    Using ab initio calculations on Zn0.975–Fe0.025CuO ( = 0, 0.01, 0.02, 0.05), we study the variations of magnetic moments vs Cu concentration. The electronic structure is calculated by using the Korringa–Kohn–Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that the total magnetic moment and magnetic moment of Fe increase on increasing Cu content. From the density of state (DOS) analysis, we show that Cu-induced impurity bands can assure, by two mechanisms, the enhancement of Fe magnetic moment in Zn0.975–Fe0.025CuO.

  11. Investigations on the preparation and optical properties of Fe-doped sheet-like ZnO crystal%Fe掺杂片状ZnO晶体的制备及光学性能研究

    Institute of Scientific and Technical Information of China (English)

    余小红; 刘长珍; 孟大维; 谢静; 王君霞

    2011-01-01

    采用均匀沉淀法在常温开放体系下制备了片状ZnO晶体前驱物,经600℃煅烧得到纯ZnO晶体;在此基础上,采用原位掺杂的方法制备了片状掺Fe的ZnO晶体。通过体视显微镜、XRD、UV-Vis吸收和PL研究了Fe掺杂对片状ZnO晶体结构和光学性能的影响。结果显示掺Fe后ZnO晶体仍具有正六边形形貌和纤锌矿结构,其在398nm处的紫外发射峰和458nm处的蓝光发射峰位置保持不变,但晶片直径减小,禁带宽度增大,发光峰强度降低。%Sheet-like ZnO crystal and sheet-like Fe-doped ZnO crystal were prepared by homogeneous precipitation method and in-situ doping method in room temperature under open system,respectively.In order to investigate the influence of Fe-doping to ZnO,we used stereomicroscope,X-ray diffractometer,fluorescence spectroscope and ultraviolet-visible-near infrared spectrophotometer to express the structure and optical properties of the samples.The result indicated that pure ZnO and Fe-doped ZnO both have hexagon shape,wurtzite structure and two photoluminescence peaks 398 and 458nm.Besides,Fe-doped ZnO crystal has 97.5% absorption rate of ultraviolet light in the range of 200 to 365nm.What's more,the diameter of the sheet-like Fe-doped ZnO crystal decreased and the energy gap increased compared to pure ZnO crystal.In addition,the lower light emission was observed when doping Fe into ZnO.

  12. Cu或Sn与Fe共掺杂对ZnO晶体形貌和磁性的影响%Effects of Cu or Sn and Fe Co-Doping on the Morphology and Magnetism of ZnO Crystals

    Institute of Scientific and Technical Information of China (English)

    刘超; 刘继文; 贾利云; 张礼刚; 韦志仁

    2012-01-01

    Through adding a certain amount of analytical pure FeSO4·7H2O and CuCl2·2H2O or SnCl2·2H2O in the precursors Zn (OH)2 , the ZnO crystals were synthesized by hydrother-mal method with 3 mol/L KOH as a mineralizer, the degree of filling of 35% , reaction temperature of 430 ℃ and reaction time of 24 h. The measuring results show that the Fe doped ZnO crystals have no magnetic saturation phenomenon and hysteresis loop at room temperature, and thus have no room temperature ferromagnetism. For Cu-Fe co-doped ZnO crystals, the drop of the magnetic moment decreases with the rise of temperature, the measuring results show that the Cu-Fe co-doped ZnO crystals have magnetic saturation phenomenon and hysteresis loop at room temperature. The morphology of Fe-Sn co-doped ZnO crystals is the best. The magnetic moment of Fe-Sn co-doped ZnO crystals is bigger, and does not fall with the rise of temperature. Fe-Sn co-doped ZnO crystals have room temperature ferromagnetism and paramagnetic. By adding Cu or Sn, the magnetism and crystal morphology of Fe doped ZnO crystals are improved.%采用水热法,在前驱物Zn (OH)2中添加一定量的分析纯FeSO4·7H2O和CuCl2·2H2O或SnCl2·2H2O,以3 mol/L KOH溶液作为矿化剂,填充度为35%,反应温度430℃,经24 h反应合成ZnO晶体.掺杂Fe的ZnO晶体室温下测量无磁饱和现象和磁滞回线,不具备室温铁磁性.Cu与Fe共掺杂合成ZnO晶体,随温度的升高其比磁化强度下降的幅度减小,室温下测量具有磁饱和现象和磁滞回线.Sn与Fe共掺杂的晶体形貌最好,且比磁化强度较大,没有随温度升高而下降,存在室温铁磁性和顺磁性.Cu或Sn元素的加入增加了掺杂Fe的ZnO晶体的磁性,改善了晶体形貌.

  13. Doped Colloidal ZnO Nanocrystals

    Directory of Open Access Journals (Sweden)

    Yizheng Jin

    2012-01-01

    Full Text Available Colloidal ZnO nanocrystals are promising for a wide range of applications due to the combination of unique multifunctional nature and remarkable solution processability. Doping is an effective approach of enhancing the properties of colloidal ZnO nanocrystals in well-controlled manners. In this paper, we analyzed two synthetic strategies for the doped colloidal ZnO nanocrystals, emphasizing our understanding on the critical factors associated with the high temperature and nonaqueous approach. Latest advances of three topics, bandgap engineering, n-type doping, and dilute magnetic semiconductors related to doped ZnO nanocrystals were discussed to reveal the effects of dopants on the properties of the nanocrystalline materials.

  14. ZnO: growth, doping & processing

    Directory of Open Access Journals (Sweden)

    D.P. Norton

    2004-06-01

    Full Text Available A review is given here of recent results in developing improved control of growth, doping, and fabrication processes for ZnO devices with possible applications to ultraviolet (UV light emitters, spin functional devices, gas sensors, transparent electronics, and surface acoustic wave devices. ZnO can be grown on cheap substrates such as glass at relatively low temperatures and may have advantages over the GaN system in some of these applications.

  15. Lattice locations and properties of Fe in Co/Fe co-implanted ZnO

    DEFF Research Database (Denmark)

    Gunnlaugsson, H.P.; Johnston, K.; Mølholt, T.E.;

    2012-01-01

    The lattice locations and electronic configurations of Fe in 57Co/57Fe implanted ZnO (to (5‐6) × 1014 Fe/cm−2) have been studied by 57Fe Mössbauer emission spectroscopy. The spectra acquired upon room temperature implantation show ∼20% of the probe atoms as Fe2+ on perturbed Zn sites and the rema...... likely takes place at relatively low temperatures, thus explaining some of the discrepancies in the literature regarding magnetic properties of 3d metal‐doped ZnO.......The lattice locations and electronic configurations of Fe in 57Co/57Fe implanted ZnO (to (5‐6) × 1014 Fe/cm−2) have been studied by 57Fe Mössbauer emission spectroscopy. The spectra acquired upon room temperature implantation show ∼20% of the probe atoms as Fe2+ on perturbed Zn sites...... and the remaining fraction as Fe2+ in damage sites of interstitial character. After annealing at 773 K, ∼20% remain on crystalline sites, while the damage fraction has partly disappeared and instead a ∼30% fraction occurs as high‐spin Fe3+, presumably in precipitates. This suggests that precipitation of Co/Fe in ZnO...

  16. Paramagnetism in Mn/Fe implanted ZnO

    CERN Document Server

    Gunnlaugsson, HP; Weyer, G; Kobayashi, Y; Bharuth-Ram, K; Olafsson, S; Gislason, H P; Gunnlaugsson, H P; Yoshida, Y; Langouche, G; Molholt, T E; Masenda, H; Johnston, K; Sielemann, R; Dlamini, W B; ISOLDE Collaboration; Naidoo, D; Mantovan, R

    2010-01-01

    Prompted by the generally poor understanding of the nature of magnetic phenomena in 3d-metal doped ZnO, we have undertaken on-line Fe-57 Mossbauer spectroscopy on ZnO single crystals in an external magnetic field of 0.6 T, following the implantation of radioactive Mn-57 ions at room temperature. The Mossbauer spectra of the dilute Fe impurities are dominated by sextets whose angular dependence rules out an ordered magnetic state (which had been previously proposed) but are well accounted for on the basis of Fe3+ paramagnetic centers on substitutional Zn sites with unusually long relaxation times (> 20 ns). (C) 2010 American Institute of Physics. {[}doi:10.1063/1.3490708

  17. Nd-doped ZnO as a multifunctional nanomaterial

    Institute of Scientific and Technical Information of China (English)

    Surender Kumar; P.D. Sahare

    2012-01-01

    Chemically synthesised ZnO and Nd-doped ZnO nanoparticles were investigated for structural,optical,magnetic properties along with photocatalytic activity.Transmission electron microscopy measurement was performed on the undoped and doped ZnO nanoparticles.Compared to the undoped ZnO,Nd-doped ZnO nanoparticles showed enhanced photoluminescent and ferromagnetic properties.The Nddoped ZnO nanoparticles also showed improved photocatalytic properties compared with the undoped ZnO nanoparticles.Furthermore,the effect of UV light irradiation was studied with thermoluminescence (TL) and photoluminescence (PL) measurement techniques.It was found that in case ofNd-doped ZnO nanoparticles TL intensity increased while the green emission in PL spectra decreased with UV-light irradiation.This was attributed to the production of more surface defects on UV irradiation on Nd-doping.

  18. First-principles Study on Infrared Absorptions of Transition Metal-doped ZnO with Oxygen Vacancy

    Institute of Scientific and Technical Information of China (English)

    Yinhua YAO; Quanxi CAO

    2013-01-01

    Using first-principle theory,the infrared absorptions of transition metal (Mn,Fe,Co,Ni)-doped ZnO were investigated.The results indicate that the absorptions of Mn-and Co-incorporated ZnO without oxygen vacancy are reduced,while those of Fe-and Ni-doped ZnO are raised.This is consistent with the previous experimental results.The effects of oxygen vacancy on the absorptions of the doped systems were predicted.When a neutral oxygen vacancy is introduced,all doping elements decrease the absorptions.On the contrary,the absorptions of the doped systems are enhanced if the vacancies are charged.Degraded absorptions can be obtained by increasing the permeability.However,the appearance of anti-bonding states may cause enhanced absorptions.In the current study,Mn-doped ZnO is the most suitable for use as low infrared absorption materials.

  19. Preparation, Characterization, and Biotoxicity of Nanosized Doped ZnO Photocatalyst

    OpenAIRE

    Lingling Liu; XiangRui Wang; Xiuping Yang; Wenhong Fan; Xiaolong Wang; Ning Wang; Xiaomin Li; Feng Xue

    2014-01-01

    Metal-doped nanosized ZnO (nZnO) photocatalyst has been widely used for its typical properties and has thus gained considerable attention. In this study, five types of nZnO (nondoped nZnO, iron- (Fe-) doped nZnO, cobalt- (Co-) doped nZnO, nickel- (Ni-) doped nZnO, and manganese- (Mn-) doped nZnO) materials were prepared through a wet chemical method and then exposed to Daphnia magna (D. magna) at low and high concentrations (50 and 250 μg L−1). Results showed that the different metal-doped nZ...

  20. Structural, magnetic and electronic structure properties of Co doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Shalendra, E-mail: shailuphy@gmail.com [Institute of Basic Sciences, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Song, T.K., E-mail: tksong@changwon.ac.kr [School of Materials Science and Engineering, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of); Gautam, Sanjeev; Chae, K.H. [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Kim, S.S.; Jang, K.W. [Institute of Basic Sciences, Changwon National University, Changwon, Gyeongnam 641-773 (Korea, Republic of)

    2015-06-15

    Highlights: • XRD and HR-TEM results show the single phase nature of Co doped ZnO nanoparticles. • XMCD and dc magnetization results indicate the RT-FM in Co doped ZnO nanoparticles. • Co L{sub 3,2} NEXAFS spectra infer that Co ions are in 2+ valence state. • O K edge NEXAFS spectra show that O vacancy increases with Co doping in ZnO. - Abstract: We reported structural, magnetic and electronic structure studies of Co doped ZnO nanoparticles. Doping of Co ions in ZnO host matrix has been studied and confirmed using various methods; such as X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersed X-ray (EDX), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, magnetic hysteresis loop measurements and X-ray magnetic circular dichroism (XMCD). From the XRD and HR-TEM results, it is observed that Co doped ZnO nanoparticles have single phase nature with wurtzite structure and exclude the possibility of secondary phase formation. FE-SEM and TEM micrographs show that pure and Co doped nanoparticles are nearly spherical in shape. O K edge NEXAFS spectra indicate that O vacancies increase with Co doping. The Co L{sub 3,2} edge NEXAFS spectra revealed that Co ions are in 2+ valence state. DC magnetization hysteresis loops and XMCD results clearly showed the intrinsic origin of temperature ferromagnetism in Co doped ZnO nanoparticles.

  1. Spin wave study and optical properties in Fe-doped ZnO thin films prepared by spray pyrolysis technique

    Science.gov (United States)

    Lmai, F.; Moubah, R.; El Amiri, A.; Abid, Y.; Soumahoro, I.; Hassanain, N.; Colis, S.; Schmerber, G.; Dinia, A.; Lassri, H.

    2016-07-01

    We investigate the magnetic and optical properties of Zn1-xFexO (x = 0, 0.03, 0.05, and 0.07) thin films grown by spray pyrolysis technique. The magnetization as a function of temperature [M (T)] shows a prevailing paramagnetic contribution at low temperature. By using spin wave theory, we separate the M (T) curve in two contributions: one showing intrinsic ferromagnetism and one showing a purely paramagnetic behavior. Furthermore, it is shown that the spin wave theory is consistent with ab-initio calculations only when oxygen vacancies are considered, highlighting the key role played by structural defects in the mechanism driving the observed ferromagnetism. Using UV-visible measurements, the transmittance, reflectance, band gap energy, band tail, dielectric coefficient, refractive index, and optical conductivity were extracted and related to the variation of the Fe content.

  2. Synthesis, Characterization, and Photocatalysis of ZnO and Er-Doped ZnO

    OpenAIRE

    Yu, Kai-sheng; Shi, Jian-ying; Zhang, Zai-Li; Liang, Yong-Mei; LIU Wei

    2013-01-01

    ZnO and Er-doped ZnO with different molar ratios of Er/Zn were prepared using the homogeneous precipitation method. The photocatalysts prepared were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), UV-vis spectroscopy, and photoluminescence spectroscopy. The results showed that the Er-doped ZnO displayed characteristic wurtzite-type peaks in the XRD spectra. The Er-doped ZnO absorbed much more light than ZnO in the ultraviolet region...

  3. A Novel Way for Synthesizing Phosphorus-Doped Zno Nanowires.

    Science.gov (United States)

    Gao, Jingyun; Zhao, Qing; Sun, Yanghui; Li, Guo; Zhang, Jingmin; Yu, Dapeng

    2011-12-01

    We developed a novel approach to synthesize phosphorus (P)-doped ZnO nanowires by directly decomposing zinc phosphate powder. The samples were demonstrated to be P-doped ZnO nanowires by using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction spectra, X-ray photoelectron spectroscopy, energy dispersive spectrum, Raman spectra and photoluminescence measurements. The chemical state of P was investigated by electron energy loss spectroscopy (EELS) analyses in individual ZnO nanowires. P was found to substitute at oxygen sites (PO), with the presence of anti-site P on Zn sites (PZn). P-doped ZnO nanowires were high resistance and the related P-doping mechanism was discussed by combining EELS results with electrical measurements, structure characterization and photoluminescence measurements. Our method provides an efficient way of synthesizing P-doped ZnO nanowires and the results help to understand the P-doping mechanism.

  4. Photoluminescence properties of Co-doped ZnO nanocrystals

    DEFF Research Database (Denmark)

    Lommens, P.; Smet, P.F.; De Mello Donega, C.

    2006-01-01

    We performed photoluminescence experiments on colloidal, Co -doped ZnO nanocrystals in order to study the electronic properties of Co in a ZnO host. Room temperature measurements showed, next to the ZnO exciton and trap emission, an additional emission related to the Co dopant. The spectral posit...

  5. Intrinsic Ferromagnetism in Eu doped ZnO

    OpenAIRE

    Assadi, M. H. N.; Zhang,Y.B.; Ionescu, M.; Photongkam, P.; Li, S.

    2010-01-01

    We report room temperature ferromagnetism in as-implanted Eu doped ZnO (ZnO:Eu). To address the origin of ferromagnetism ab initio calculations of ZnO:Eu system are performed. Results show that the ferromagnetism is induced by ZnO point defects as Eu ions in perfect ZnO tend to align antiferromagnetically.

  6. Effects of doping concentration on properties of Mn-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    Gao Li; Zhang Jian-Min

    2009-01-01

    This paper reports that the radio frequency magnetron sputtering is used to fabricate ZnO and Mn-doped ZnO thin films on glass substrates at 500 ℃. The Mn-doped ZnO thin films present wurtzite structure of ZnO and have a smoother surface, better conductivity but no ferromagnetism. The x-ray photoelectron spectroscopy results show that the binding energy of Mn_(2p3/2) increases with increasing Mn content slightly, and the state of Mn in the Mn-doped ZnO thin films is divalent. The chemisorbed oxygen in the Mn-doped ZnO thin films increases with increasing Mn doping concentration. The photoluminescence spectra of ZnO and Mn-doped ZnO thin films have a similar ultraviolet emission. The yellow green emissions of 4 wt. % and 10 wt. % Mn-doped thin films are quenched, whereas the yellow green emission occurs because of abundant oxygen vacancies in the Mn-doped ZnO thin films after 20 wt. % Mn doping. Compared with pure ZnO thin film, the bandgap of the Mn-doped ZnO thin films increases with increasing Mn content.

  7. Oxygen vacancy induced by La and Fe into ZnO nanoparticles to modify ferromagnetic ordering

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Kuldeep Chand, E-mail: kuldeep0309@yahoo.co.in [Centre of Advanced Study in Physics, Department of Physics, Panjab University, Chandigarh 160 014 (India); Kotnala, R.K., E-mail: rkkotnala@gmail.com [CSIR-National Physical Laboratory, New Delhi 110012 (India)

    2016-05-15

    We reported long-range ferromagnetic interactions in La doped Zn{sub 0.95}Fe{sub 0.05}O nanoparticles that mediated through lattice defects or vacancies. Zn{sub 0.92}Fe{sub 0.05}La{sub 0.03}O (ZFLaO53) nanoparticles were synthesized by a sol–gel process. X-ray fluorescence spectrum of ZFLaO53 detects the weight percentage of Zn, Fe, La and O. X-ray diffraction shows the hexagonal Wurtzite ZnO phase. The Rietveld refinement has been used to calculate the lattice parameters and the position of Zn, Fe, La and O atoms in the Wurtzite unit cell. The average size of ZFLaO53 nanoparticles is 99 nm. The agglomeration type product due to OH ions with La results into ZnO nanoparticles than nanorods that found in pure ZnO and Zn{sub 0.95}Fe{sub 0.05}O sample. The effect of doping concentration to induce Wurtzite ZnO structure and lattice defects has been analyzed by Raman active vibrational modes. Photoluminescence spectra show an abnormal emission in both UV and visible region, and a blue shift at near band edge is formed with doping. The room temperature magnetic measurement result into weak ferromagnetism but pure ZnO is diamagnetic. However, the temperature dependent magnetic measurement using zero-field and field cooling at dc magnetizing field 500 Oe induces long-range ferromagnetic ordering. It results into antiferromagnetic Neel temperature of ZFLaO53 at around 42 K. The magnetic hysteresis is also measured at 200, 100, 50 and 10 K measurement that indicate enhancement in ferromagnetism at low temperature. Overall, the La doping into Zn{sub 0.95}Fe{sub 0.05}O results into enhanced antiferromagnetic interaction as well as lattice defects/vacancies. The role of the oxygen vacancy as the dominant defects in doped ZnO must form Bound magnetic polarons has been described. - Graphical abstract: The long-range ferromagnetic order in Zn{sub 0.92}Fe{sub 0.05}La{sub 0.03}O nanoparticles at low temperature measurements involves oxygen vacancy as the medium of magnetic

  8. Oxygen vacancy induced by La and Fe into ZnO nanoparticles to modify ferromagnetic ordering

    Science.gov (United States)

    Verma, Kuldeep Chand; Kotnala, R. K.

    2016-05-01

    We reported long-range ferromagnetic interactions in La doped Zn0.95Fe0.05O nanoparticles that mediated through lattice defects or vacancies. Zn0.92Fe0.05La0.03O (ZFLaO53) nanoparticles were synthesized by a sol-gel process. X-ray fluorescence spectrum of ZFLaO53 detects the weight percentage of Zn, Fe, La and O. X-ray diffraction shows the hexagonal Wurtzite ZnO phase. The Rietveld refinement has been used to calculate the lattice parameters and the position of Zn, Fe, La and O atoms in the Wurtzite unit cell. The average size of ZFLaO53 nanoparticles is 99 nm. The agglomeration type product due to OH ions with La results into ZnO nanoparticles than nanorods that found in pure ZnO and Zn0.95Fe0.05O sample. The effect of doping concentration to induce Wurtzite ZnO structure and lattice defects has been analyzed by Raman active vibrational modes. Photoluminescence spectra show an abnormal emission in both UV and visible region, and a blue shift at near band edge is formed with doping. The room temperature magnetic measurement result into weak ferromagnetism but pure ZnO is diamagnetic. However, the temperature dependent magnetic measurement using zero-field and field cooling at dc magnetizing field 500 Oe induces long-range ferromagnetic ordering. It results into antiferromagnetic Neel temperature of ZFLaO53 at around 42 K. The magnetic hysteresis is also measured at 200, 100, 50 and 10 K measurement that indicate enhancement in ferromagnetism at low temperature. Overall, the La doping into Zn0.95Fe0.05O results into enhanced antiferromagnetic interaction as well as lattice defects/vacancies. The role of the oxygen vacancy as the dominant defects in doped ZnO must form Bound magnetic polarons has been described.

  9. Effect of Sm doping on the physical properties of ZnO thin films deposited by spray pyrolysis technique

    Science.gov (United States)

    Velusamy, P.; Babu, R. Ramesh; Aparna, K. T.

    2017-05-01

    Undoped and Sm doped ZnO thin films have been prepared by chemical spray pyrolysis method on a glass substrate at 430°C. The physical properties of undoped and Sm doped ZnO thin films are characterized by XRD, FE-SEM, UV-VIS spectroscopy, Hall measurement and PL analysis. XRD pattern reveals that all the films are polycrystalline nature. The FE-SEM study of CdO shows the smooth and uniform surface with the spherical shaped particle. The electrical study reveals the n-type semiconductor and the optical study shows that Sm doped ZnO thin films about 92% transparency and optical band gap vary between 3.266-3.276 eV. Sm doped ZnO thin films have strong green emission behavior.

  10. YAlO3/Fe掺杂ZnO复合物的制备、表征及对酸性红B的降解%Synthesis and Characterization of YAlO3/Fe-doped ZnO and Its Photocatalytic Oxidation of Acid Red B

    Institute of Scientific and Technical Information of China (English)

    程春萍

    2012-01-01

    In this work,YAlO3/Fe -doped ZnO composite,a novel photocatalyst, was synthesized by ultrasonic disper-sion and liquid boiling method and characterized by X - ray diffraction ( XRD ) and scanning electron microscope ( SEM) , and its photocatalytic activities were evaluated through the degradation of acid red B under visible light irradiation. The effects of preparation conditions such as YAlO3 content, heat - treated temperature and heat - treated time on the photocatalytic activity of YAlO3/Fe - doped ZnO composite were examined. In addition,the influences of visible light irradiation time and YAlO3/Fe - doped ZnO amount as well as organic dyes on the photocatalytic degradation were also investigated by HPLC techniques. The experimental results indicated that the YAlO3/Fe - doped ZnO composite can effectively utilize visible energy to degrade acid red B and its photocatalytic activity was much superior to that of Fe - doped ZnO composite under the same condition. Results revealed that the AlO3/Fe - doped ZnO showed higher activity and the maximum conversion of acid red B could reach 97.7% within 40 min.%采用溶胶-凝胶、超声分散和溶液沸腾法制备YAlO3/Fe掺杂ZnO复合物,在可见光的照射下,考察了酸性红B降解效果,并利用x-射线衍射(XRD)和扫描电子显微镜(SEM)对光催化剂进行了表征,同时研究了YAlO3的包覆量、YAlO3/Fe掺杂ZnO的量、可见光照射时间、处理温度和处理时间等因素对酸性红B降解率的影响,其降解过程也用HPLC进一步进行验证.结果表明,YAlO3/Fe掺杂ZnO在40 min酸性红B的降解率达到97.7%,表现出更好的光催化活性.

  11. Low temperature doping of ZnO nanostructures

    Institute of Scientific and Technical Information of China (English)

    M.A.THOMAS; H.KANDEL; Y.C.SOO

    2009-01-01

    Doping of ZnO nanostructures was investigated by using a low temperature electrochemical process. Various dopant materials have been studied, including transition metals, group I, and group VII elements. The structure, composition, and optical properties of the doped ZnO nanostructures were analyzed by scanning electron microscopy, energy dispersive X-ray spectroscopy, photoluminescence, and x-ray diffraction. It was demonstrated that dopant elements were incorporated into the ZnO structures. The effects of dopant incorporation on the structure and properties of ZnO were also investigated. This low temperature approach is compatible with current micro-fabrication techniques and promising for large-scale production of doped ZnO nanostructures for optical and electronic applications.

  12. Intrinsic and extrinsic doping of ZnO and ZnO alloys

    Science.gov (United States)

    Ellmer, Klaus; Bikowski, André

    2016-10-01

    In this article the doping of the oxidic compound semiconductor ZnO is reviewed with special emphasis on n-type doping. ZnO naturally exhibits n-type conductivity, which is used in the application of highly doped n-type ZnO as a transparent electrode, for instance in thin film solar cells. For prospective application of ZnO in other electronic devices (LEDs, UV photodetectors or power devices) p-type doping is required, which has been reported only minimally. Highly n-type doped ZnO can be prepared by doping with the group IIIB elements B, Al, Ga, and In, which act as shallow donors according to the simple hydrogen-like substitutional donor model of Bethe (1942 Theory of the Boundary Layer of Crystal Rectifiers (Boston, MA: MIT Rad Lab.)). Group IIIA elements (Sc, Y, La etc) are also known to act as shallow donors in ZnO, similarly explainable by the shallow donor model of Bethe. Some reports showed that even group IVA (Ti, Zr, Hf) and IVB (Si, Ge) elements can be used to prepare highly doped ZnO films—which, however, can no longer be explained by the simple hydrogen-like substitutional donor model. More probably, these elements form defect complexes that act as shallow donors in ZnO. On the other hand, group V elements on oxygen lattice sites (N, P, As, and Sb), which were viewed for a long time as typical shallow acceptors, behave instead as deep acceptors, preventing high hole concentrations in ZnO at room temperature. Also, ‘self’-compensation, i.e. the formation of a large number of intrinsic donors at high acceptor concentrations seems to counteract the p-type doping of ZnO. At donor concentrations above about 1020 cm-3, the electrical activation of the dopant elements is often less than 100%, especially in polycrystalline thin films. Reasons for the electrical deactivation of the dopant atoms are (i) the formation of dopant-defect complexes, (ii) the compensation of the electrons by acceptors (Oi, VZn) or (iii) the formation of secondary phases, for

  13. Ferromagnetism in ZnO doped with alkaline elements

    Science.gov (United States)

    Wang, Yiren; Piao, Jingyuan; Xin, Guozhong; Lu, Yunhao; Ao, Zhimin; Bao, Nina; Ding, Jun; Li, Sean; Yi, Jiabao

    We have observed room temperature ferromagnetism (RTFM) in ZnO doped with alkaline elements Using first-principles calculations we found the magnetization in these systems is originated from the O2p hole states around Zn vacancies. Calculations indicate that the formation energy of Zn vacancies alone is rather high while further investigation indicates the formation can be much stabilized by the alkaline dopants in the form of defect complexes. By calculating the formation energy of concerned defects and complexes, we found the role of the dopants that under a certain doping concentration: Zn vacancy, substitutional and interstitial dopants can form a defect complex, which can lower formation energy, therefore stabilizing Zn vacancies. Moreover K dopants have shown unique functions on the ferromagnetism since the substitutional K can induce magnetic moments to the system by forming partial zinc vacancy via lattice distortion. Hence K doped ZnO can be magnetic at low doping concentrations. Experimentally, Li, Na doped ZnO films and K doped ZnO nanorods with different doping levels are synthesized, RTFM can be observed in all these systems. The magnetization is found to be greatly influenced by the doping concentrations. The experimental results have shown good consistence with our theoretical calculations. Our studies can inspire the defect induced ferromagnetism as a new route for the fabrication of new diluted magnetic semiconductors.

  14. Visible light photo-degradation of methylene blue over Fe or Cu promoted ZnO nanoparticles.

    Science.gov (United States)

    Mardani, Hamid Reza; Forouzani, Mehdi; Ziari, Mitra; Biparva, Pourya

    2015-04-15

    CuxZn(1-x)O, FexZn(1-x)O (x=0.01) and ZnO nanoparticles were and were characterized by X-ray diffraction, ultraviolet and visible spectroscopy, FTIR spectroscopy and SEM. The photodegradation of an aqueous solution of methylene blue (as an organic pollutant) by nanoparticles with H2O2 (30%) under visible light and the progress of the reaction were monitored by UV-Vis spectroscopy absorption. The photocatalytic oxidation efficiency of all nanoparticles was 100% at the appropriate time. The degradation time was 90 min for FeZnO, 120 min for CuZnO and 210 min for ZnO. This indicates that the photocatalytic activity of the doped nanoparticles was better than that of ZnO alone. ZnO doped with a small amount of Fe or Cu decreased the size of the nanoparticles and the band gap and increased photocatalytic efficiency.

  15. A comparative study on the structural properties of ZnO and Ni-doped ZnO nanostructures

    OpenAIRE

    Kim, Kyungho; Jin, Zhuguang; Abe, Yoshio; Kawamura, Midori; 金, 敬鎬; 阿部, 良夫; 川村, みどり

    2015-01-01

    We investigated the structural properties of zinc oxide (ZnO) nanorods with various Ni doping amounts. The length and diameter of the nanorods decreased and increased, respectively, with increasing Ni doping amount to 5 mM. Ni-doped ZnO (Ni-ZnO) nanorods exhibited better crystalline quality than undoped ZnO nanorods. In the visible wavelength region, the optical transmittance of Ni-ZnO nanorods was slightly lower than that of ZnO nanorods. Upon further increasing the Ni doping amount (7 mM), ...

  16. High Performance Indium-Doped ZnO Gas Sensor

    Directory of Open Access Journals (Sweden)

    Junjie Qi

    2015-01-01

    Full Text Available Gas sensors for ethanol and acetone based on ZnO nanobelts with doping element indium were fabricated. Excellent sensitivity accompanied with short response time (10 s and recovery time (23 s to 150 ppm ethanol is obtained. For In-doped sensors, a minimum concentration of 37.5 ppm at 275°C in acetone was observed with an average sensitivity of 714.4, which is 7 times larger than that of the pure sensors and much larger than that reported response (16 of Co-doped ZnO nanofibers to acetone. These results indicate that doping elements can improve gas sensitivity, which is associated with oxygen space and valence ions. In-doped ZnO nanobelts exhibit higher sensitivity to acetone than that to ethanol. These results indicate that doped ZnO nanobelts can successfully distinguish acetone and ethanol, which can be put into various practical applications.

  17. Development in p-type Doping of ZnO

    Institute of Scientific and Technical Information of China (English)

    YU Liping; ZHU Qiqiang; FAN Dayong; LAN Zili

    2012-01-01

    Zinc oxide (ZnO) is a wide band-gap material of the Ⅱ-Ⅵ group with excellent optical properties for optoelectronics applications,such as the flat panel displays and solar cells used in sports tournament.Despite its advantages,the application of ZnO is hampered by the lack of stable p-type doping.In this paper,the recent progress in this field was briefly reviewed,and a comprehensive summary of the research was carried out on ZnO fabrication methods and its electrical,optical,and magnetic properties were presented.

  18. Green emission in carbon doped ZnO films

    Directory of Open Access Journals (Sweden)

    L. T. Tseng

    2014-06-01

    Full Text Available The emission behavior of C-doped ZnO films, which were prepared by implantation of carbon into ZnO films, is investigated. Orange/red emission is observed for the films with the thickness of 60–100 nm. However, the film with thickness of 200 nm shows strong green emission. Further investigations by annealing bulk ZnO single crystals under different environments, i.e. Ar, Zn or C vapor, indicated that the complex defects based on Zn interstitials are responsible for the strong green emission. The existence of complex defects was confirmed by electron spin resonance (ESR and low temperature photoluminescence (PL measurement.

  19. Green emission in carbon doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, L. T.; Yi, J. B., E-mail: jiabao.yi@unsw.edu.au; Zhang, X. Y.; Xing, G. Z.; Luo, X.; Li, S. [School of Materials Science and Engineering, University of New South Wales, Kensington, NSW, 2052 (Australia); Fan, H. M. [School of Chemical Engineering, Northwest University, Xi' an 710069 (China); Herng, T. S.; Ding, J. [Department of Materials Science and Engineering, National University of Singapore, 119260 (Singapore); Ionescu, M. [Australian Nuclear Science and Technology Organization, (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234 (Australia)

    2014-06-15

    The emission behavior of C-doped ZnO films, which were prepared by implantation of carbon into ZnO films, is investigated. Orange/red emission is observed for the films with the thickness of 60–100 nm. However, the film with thickness of 200 nm shows strong green emission. Further investigations by annealing bulk ZnO single crystals under different environments, i.e. Ar, Zn or C vapor, indicated that the complex defects based on Zn interstitials are responsible for the strong green emission. The existence of complex defects was confirmed by electron spin resonance (ESR) and low temperature photoluminescence (PL) measurement.

  20. Doping dependent properties of Cr-doped ZnO nanostructures prepared by microwave irradiation.

    Science.gov (United States)

    Ahmed, Faheem; Arshi, Nishat; Anwar, M S; Koo, Bon Heun

    2014-11-01

    In this work, undoped and Cr-doped single-crystalline ZnO nanorods were prepared by a facile microwave assisted solution method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results showed that Cr-doped ZnO was comprised of single phase nature with hexagonal wurtzite structure up to 5% Cr doping, however, secondary phase ZnCr2O4 appeared upon further increasing the Cr dopant concentration. Field emission scanning electron microscopy (FESEM) and TEM micrographs suggested that the undoped nanorods with an average length of -~2 μm and a diameter in the range of 150-200 nm, respectively were observed. Interestingly, the size of nanorods decreased with the increase of Cr concentration in ZnO. Optical studies depicted that the energy bandgap was decreased with the increase of Cr concentration. Raman scattering spectra of Cr-doped ZnO revealed the lower frequency shift of E2(high) phonon mode with the increase in concentration of Cr dopant, suggested the successful doping of Cr into Zn site in ZnO. Magnetic studies showed that Cr-doped ZnO exhibited room temperature ferromagnetism (RTFM) and the value of magnetization was continuously decreased with the increase in Cr doping.

  1. Luminance behavior of lithium-doped ZnO nanowires with p-type conduction characteristics.

    Science.gov (United States)

    Ko, Won Bae; Lee, Jun Seok; Lee, Sang Hyo; Cha, Seung Nam; Sohn, Jung Inn; Kim, Jong Min; Park, Young Jun; Kim, Hyun Jung; Hong, Jin Pyo

    2013-09-01

    The present study describes the room-temperature cathodeluminescence (CL) and temperature-dependent photoluminescence (PL) properties of p-type lithium (Li)-doped zinc oxide (ZnO) nanowires (NWs) grown by hydrothermal doping and post-annealing processes. A ZnO thin film was used as a seed layer in NW growth. The emission wavelengths and intensities of undoped ZnO NWs and p-type Li-doped ZnO NWs were analyzed for comparison. CL and PL observations of post-annealed p-type Li-doped ZnO NWs clearly exhibited a dominant sharp band-edge emission. Finally, a n-type ZnO thin film/p-type annealed Li-doped ZnO NW homojunction diode was prepared to confirm the p-type conduction of annealed Li-doped ZnO NWs as well as the structural properties measured by transmission electron microscopy.

  2. Paramagnetism and antiferromagnetic interactions in single-phase Fe-implanted ZnO

    CERN Document Server

    Pereira, Lino Miguel da Costa; Correia, João Guilherme; Van Bael, M J; Temst, Kristiaan; Vantomme, André; Araújo, João Pedro

    2013-01-01

    As the intrinsic origin of the high temperature ferromagnetism often observed in wide-gap dilute magnetic semiconductors becomes increasingly debated, there is a growing need for comprehensive studies on the single-phase region of the phase diagram of these materials. Here we report on the magnetic and structural properties of Fe-doped ZnO prepared by ion implantation of ZnO single crystals. A detailed structural characterization shows that the Fe impurities substitute for Zn in ZnO in a wurtzite Zn$_{1−x}$Fe$_{x}$O phase which is coherent with the ZnO host. In addition, the density of beam-induced defects is progressively decreased by thermal annealing up to 900$^{\\circ}$C, from highly disordered after implantation to highly crystalline upon subsequent annealing. Based on a detailed analysis of the magnetometry data, we demonstrate that isolated Fe impurities occupying Zn substitutional sites behave as localized paramagnetic moments down to 2$^{\\circ}$K, irrespective of the Fe concentration and the density...

  3. Transparent conductivity modulation of ZnO by group-IVA doping

    Science.gov (United States)

    Liu, J.; Fan, X. F.; Sun, C. Q.; Zhu, W.

    2016-04-01

    We examined the effect of group-IVA doping on the electronic structure and transmittance of ZnO using first-principle calculations. All these doped ZnO materials are found to perform n-type conductive behavior. Si-doped ZnO and Pb-doped ZnO are found to have larger optical band gap than those of Ge-doped ZnO and Sn-doped ZnO. The transmittance of Si-doped ZnO is found to be high in both UV and visible region. The enhancement of UV region transmittance can be attributed to the enhanced optical band gap, while the reduction of visible region transmittance is due to the intraband optical transition.

  4. Effect of copper and nickel doping on the optical and structural properties of ZnO

    Science.gov (United States)

    Muǧlu, G. Merhan; Sarıtaş, S.; ćakıcı, T.; Şakar, B.; Yıldırım, M.

    2017-02-01

    The present study is focused on the Cu doped ZnO and Ni doped ZnO dilute magnetic semiconductor thin films. ZnO:Cu and ZnO:Ni thin films were grown by Chemically Spray Pyrolysis (CSP) method on glass substrates. Optical analysis of the films was done spectral absorption and transmittance measurements by UV-Vis double beam spectrophotometer technique. The structure, morphology, topology and elemental analysis of ZnO:Cu and ZnO:Ni dilute magnetic thin films were investigated by X-ray diffraction (XRD), Raman Analysis, field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy (AFM) techniques, respectively. Also The magnetic properties of the ZnO:Ni thin film was investigated by vibrating sample magnetometer (VSM) method. VSM measurements of ZnO:Ni thin film showed that the ferromagnetic behavior.

  5. Room temperature ferromagnetism in Cu-doped ZnO synthesized from CuO and ZnO nanoparticles

    Science.gov (United States)

    Owens, Frank J.

    2009-11-01

    AC susceptibility and ferromagnetic resonance (FMR) measurements indicate that ZnO doped with Cu by a simple sintering process starting from nanoparticles of ZnO and CuO is ferromagnetic above room temperature. FMR measurements above room temperature indicate the ordering temperature to be above 520 K. The observation supports the recent theoretical calculations of Huang et al. which predict ferromagnetism in copper-doped ZnO.

  6. First-Principles Study of Magnetic Properties of 3dTransition Metals Doped in ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    Duan Yifeng

    2009-01-01

    Full Text Available Abstract The defect formation energies of transition metals (Cr, Fe, and Ni doped in the pseudo-H passivated ZnO nanowires and bulk are systematically investigated using first-principles methods. The general chemical trends of the nanowires are similar to those of the bulk. We also show that the formation energy increases as the diameter of the nanowire decreases, indicating that the doping of magnetic ions in the ZnO nanowire becomes more difficult with decreasing diameter. We also systematically calculate the ferromagnetic properties of transition metals doped in the ZnO nanowire and bulk, and find that Cr ions of the nanowire favor ferromagnetic state, which is consistent with the experimental results. We also find that the ferromagnetic coupling state of Cr is more stable in the nanowire than in the bulk, which may lead to a higherT cuseful for the nano-materials design of spintronics.

  7. Thermoelectric Properties of Al-Doped Mesoporous ZnO Thin Films

    OpenAIRE

    Min-Hee Hong; Chang-Sun Park; Won-Seon Seo; Young Soo Lim; Jung-Kun Lee; Hyung-Ho Park

    2013-01-01

    Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thi...

  8. Sonochemical Synthesis of Er3+-Doped ZnO Nanospheres with Enhanced Upconversion Photoluminescence

    OpenAIRE

    Jun Geng; Guang-Hui Song; Jun-Jie Zhu

    2012-01-01

    Er3+-doped ZnO nanospheres have been synthesized via a sonochemical conversion process. The formation mechanism of these nanocrystals is connected with the sonochemical effect of ultrasound irradiation. The as-prepared Er3+ doped ZnO nanospheres show enhanced photoluminescence and upconversion photoluminescence properties compared with pure ZnO.

  9. Controlled fabrication of oriented co-doped ZnO clustered nanoassemblies.

    Science.gov (United States)

    Barick, K C; Aslam, M; Dravid, Vinayak P; Bahadur, D

    2010-09-01

    Clustered nanoassemblies of Mn doped ZnO and co-doped ZnO (Mn, Sn co-doped ZnO; Mn, Sb co-doped ZnO; and Mn, Bi co-doped ZnO) were prepared by refluxing their respective precursors in diethylene glycol medium. The co-doping elements, Sn, Sb and Bi exist in multi oxidation states by forming Zn-O-M (M=Sb, Bi and Sn) bonds in hexagonal wurtzite nanostructure. The analyses of detailed structural characterization performed by XRD, X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), show that co-doping ions are successfully incorporated into the ZnO nanostructure and do not appear as precipitates or secondary phases. HRTEM analysis also confirmed the oriented attachment of nanocrystals as well as their defect structures. The formation/activation of higher amount of intrinsic host defects, for instance, oxygen vacancies in co-doped ZnO as compared to Mn doped ZnO sample is evident from Raman spectra. The doped and co-doped samples exhibit ferromagnetic like behavior at room temperature presumably due to the presence of defects. Specifically, it has been observed that the incorporation of dopant and co-dopants into ZnO structure can modulate the local electronic structure due to the formation/activation of defects and hence, cause significant changes in their structural, vibrational, optical and magnetic properties.

  10. Growth and properties of electrodeposited transparent Al-doped ZnO nanostructures

    Science.gov (United States)

    Baka, O.; Mentar, L.; Khelladi, M. R.; Azizi, A.

    2015-12-01

    Al-doped zinc oxide (AZO) nanostructures were fabricated on fluorine-doped tin-oxide (FTO)- coated glass substrates by using electrodeposition. The effects of the doping concentration of Al on the morphological, microstructural, electrical and optical properties of the nanostructures were investigated. From the field emission scanning electron microscopy (FE-SEM) observation, when the amount of Al was increased in the solution, the grains size was observed to decreases. The observed changes in the morphology indicate that Al acts as nucleation centers in the vacancy sites of ZnO and destroys the crystalline structure at high doping level. Effectively, the X-ray diffraction (XRD) analysis indicated that the undoped and the doped ZnO nanostructures has a polycrystalline nature and a hexagonal wurtzite structure with a (002) preferential orientation. The photoluminescence (PL) room-temperature measurements showed that the incorporation of Al in the Zn lattice can improve the intensity of ultraviolet (UV) emission, thus suggesting its greater prospects for use in UV optoelectronic devices.

  11. Enhancement in conductivity through Ga, Al dual doping of ZnO nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Park, Minkyu; Han, Seung Min, E-mail: smhan01@kaist.ac.kr

    2015-09-01

    In this study, electrical conductivity of Al doped ZnO nanofiber was enhanced by using Ga co-doping over the maximum conductivity achievable with only Al dopants of 2 at.% in ZnO. Al and Ga have different atomic sizes that results in further doping with Ga up to 1 at.%. Al, Ga co-doped ZnO nanofiber was fabricated by using electrospinning technique and structural analysis was investigated by X-ray diffraction. X-ray analysis indicates a change in lattice parameter(a-axis) of doped ZnO from 3.2497 Å to 3.2483 Å with added 1 at.% Al and from 3.2497 Å to 3.2488 Å with co-doping of 1 at.% Ga on top of the 2 at.% of Al doped ZnO. Therefore, Ga was incorporated into Al doped ZnO nanofiber without significant lattice parameter and grain size reduction to result in the enhanced conductivity up to a maximum value of 9.57 × 10{sup −3} S/cm. - Highlights: • Al, Ga co-doped ZnO nanofiber is synthesized by electrospinning methods. • Al, Ga co-doped nanofiber shows the higher electrical conductivity compared to Al doped ZnO nanofiber. • AGZO nanofiber shows higher conductivity due to its higher crystallinity.

  12. Room Temperature Ferromagnetism of (Mn,Fe Codoped ZnO Nanowires Synthesized by Chemical Vapor Deposition

    Directory of Open Access Journals (Sweden)

    Yongqin Chang

    2011-01-01

    Full Text Available (Mn,Fe codoped ZnO nanowires were synthesized on silicon substrates in situ using a chemical vapor deposition method. The structure and property of the products were investigated by X-ray, electron microscopy, Raman, photoluminescence, and superconducting quantum interference device magnetometer. The doped nanowires are of pure wurtzite phase with single crystalline, and the elements distribute homogeneously in the doped nanowires. Photoluminescence spectrum of the doped nanowires is dominated by a deep-level emission with a negligible near-band-edge emission. The magnetic hysteresis curve with a coercive field of 35 Oe is clearly observed at 300 K, resulting from room-temperature ferromagnetic ordering in the (Mn,Fe codoped ZnO nanowires, which has great potential applications for spintronics devices.

  13. Electrical property studies on chemically processed polypyrolle/aluminum doped ZnO based hybrid heterostructures

    Science.gov (United States)

    Mohan Kumar, G.; Ilanchezhiyan, P.; Madhan Kumar, A.; Yuldashev, Sh. U.; Kang, T. W.

    2016-04-01

    A hybrid structure based on p-type polypyrolle (PPy) and n-type aluminum (Al) doped ZnO nanorods was successfully constructed. The effect of Al doping on material properties of wurtzite structured ZnO were studied using several analytical techniques. To establish the desired hybrid structure, pyrrole monomers were polymerized on hydrothermally grown Al doped ZnO nanorods by chemical polymerization. The current⿿voltage characteristics on the fabricated PPy/Al doped ZnO heterostructures were found to exhibit excellent rectifying characteristics under dark and illumination conditions. The obtained results augment the prescribed architecture to be highly suitable for high-sensitivity optoelectronic applications.

  14. Synthesis, characterization and photoluminescence property of La-doped ZnO nanoparticles

    Science.gov (United States)

    Lang, Jihui; Fang, Yue; Zhang, Qi; Wang, Jiaying; Li, Tianshun; Li, Xiuyan; Han, Qiang; Wang, Dandan; Wei, Maobin; Yang, Jinghai

    2016-10-01

    La-doped ZnO nanoparticles were synthesized via a facile and surfactant-free chemical precipitation route, and the effects of lanthanum doping concentration on the structures, morphologies and photoluminescence properties were investigated by XRD, TEM, EDX, PL and UV-Vis absorption spectra. The results showed that the La3+ ions were successfully incorporated into the ZnO host, and the products were well-crystalline. The average size and band gap of La-doped ZnO nanoparticles were varied with the lanthanum doping concentration. The average size of doped nanoparticles was much smaller as compared to that of undoped ZnO. The increasing of lanthanum doping concentration increased the defects in ZnO and resulted in a red shift of UV emission, indicating the narrow band gap in doped nanoparticles. This was probably attributed to the impurity energy levels in band gap introduced by substitutional La3+ ions.

  15. Al-doped ZnO nanofilms: Synthesis and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Huczko, A.; Dabrowska, A. [Department of Chemistry, Warsaw University, Warsaw (Poland); Madhup, D.K. [Department of Physics, Kathmandu University, Dhulikhel (Nepal); College of Biomedical Engineering and Applied Sciences, Hadigaun, Kathmandu (Nepal); Subedi, D.P.; Chimouriya, S.P. [Department of Physics, Kathmandu University, Dhulikhel (Nepal)

    2010-12-15

    Al-doped and un-doped ZnO nanofilms on quartz substrate were obtained by ultrasonic spray pyrolysis of salt solutions (mole concentration of Al within 0-10%). The films were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Atomic force microscopy (AFM) and UV spectroscopy to study the morphology and optical properties. The optical studies showed that the increase in Al within ZnO thin layer increases its band gap energy. The obtained value of band gap energy is very close to the determined oscillation energy. However, the dispersion energy is nearly half of band gap energy value. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Preparation and characterization of Ce-doped ZnO nanofibers by an electrospinning method

    Directory of Open Access Journals (Sweden)

    Jong-Pil Kim

    2011-02-01

    Full Text Available ZnO and Ce-doped ZnO Nanofibers on (111 Pt/SiO2/Si substrates were produced using an electrospinning technique. The as-prepared composite fibres were subjected to high-temperature calcination to produce inorganic fibers. After calcining at a temperature of 500 °C, the average diameter of the ZnO and Ce-doped ZnO nanofibers were determined to be 170 nm and 225 nm, respectively. The average grain size of the ZnO and Ce-doped ZnO nanofibers were about 50 nm and 57 nm, respectively. The microstructure, chemical bonding state and photoluminescence of the produced ZnO and Ce-doped ZnO nanofibers were investigated. The Ce-doped ZnO nanofiber can be assigned to the presence of Ce ions on substitutional sites of Zn ions and the Ce3+ state from X-ray photoelectron spectra. Compared with PL spectra of ZnO nanofibers, the peak position of the UV emission of the Ce-doped ZnO nanofibers is sharply suppressed while the green emission band is highly enhanced.

  17. Photoluminescence quenching in cobalt doped ZnO nanocrystals

    OpenAIRE

    Sekika Yamamoto

    2012-01-01

    Influence of cobalt doping on the luminescence properties of ZnO nanocrystals with average diameter of 3.0 nm is investigated. Time resolved measurements at 20 K show that the dark exciton luminescence is completely lost in the nanocrystals doped with cobalt, while the perturbed luminescence with slight red shift survives and exhibits a non-exponential decay curve reflecting random distribution of cobalt atoms. By analyzing the non-exponentiality, the increase of the decay rate of the band-ed...

  18. Optoelectronic properties of doped hydrothermal ZnO thin films

    KAUST Repository

    Mughal, Asad J.

    2017-03-10

    Group III impurity doped ZnO thin films were deposited on MgAl2O3 substrates using a simple low temperature two-step deposition method involving atomic layer deposition and hydrothermal epitaxy. Films with varying concentrations of either Al, Ga, or In were evaluated for their optoelectronic properties. Inductively coupled plasma atomic emission spectroscopy was used to determine the concentration of dopants within the ZnO films. While Al and Ga-doped films showed linear incorporation rates with the addition of precursors salts in the hydrothermal growth solution, In-doped films were shown to saturate at relatively low concentrations. It was found that Ga-doped films showed the best performance in terms of electrical resistivity and optical absorbance when compared to those doped with In or Al, with a resistivity as low as 1.9 mΩ cm and an optical absorption coefficient of 441 cm−1 at 450 nm.

  19. Ecofriendly synthesis and solar photocatalytic activity of S-doped ZnO.

    Science.gov (United States)

    Patil, Ashokrao B; Patil, Kashinath R; Pardeshi, Satish K

    2010-11-15

    The S-doped ZnO was prepared by new ecofriendly method, which involves simple mechanochemical synthesis followed by thermal decomposition of bisthiourea zinc oxalate (BTZO) powders. The BTZO was characterized by FTIR and TG-DTA analysis while S-doped ZnO crystallite was characterized by XRD, XPS, SEM, EDXS, and photoluminescence (PL) spectra. X-ray diffraction data suggest the single phase wurtzite structure for S-doped ZnO and the incorporation of sulfur expand the lattice constants of ZnO. Room temperature PL spectra show more number of oxygen vacancies in S-doped ZnO as compare to that of pure ZnO. Photocatalytic activity of S-doped ZnO was checked by means of solar photocatalytic degradation (PCD) of resorcinol, using a batch photoreactor. The PCD efficiency of S-doped ZnO was found to be 2 times greater than that of pure ZnO. The inherent relationship between PL intensity and photocatalytic activity of S-doped ZnO was discussed.

  20. Controllable Growth of Ultrathin P-doped ZnO Nanosheets.

    Science.gov (United States)

    Zhu, Yuankun; Yang, Hengyan; Sun, Feng; Wang, Xianying

    2016-12-01

    Ultrathin phosphor (P)-doped ZnO nanosheets with branched nanowires were controllably synthesized, and the effects of oxygen and phosphor doping on the structural and optical properties were systematically studied. The grown ZnO nanosheet exhibits an ultrathin nanoribbon backbone with one-side-aligned nanoteeth. For the growth of ultrathin ZnO nanosheets, both oxygen flow rate and P doping are essential, by which the morphologies and microstructures can be finely tuned. P doping induces strain relaxation to change the growth direction of ZnO nanoribbons, and oxygen flow rate promotes the high supersaturation degree to facilitate the growth of nanoteeth and widens the nanoribbons. The growth of P-doped ZnO in this work provides a new progress towards the rational control of the morphologies for ZnO nanostructures.

  1. Preparation,characterization and infrared emissivity study of Ce-doped ZnO films

    Institute of Scientific and Technical Information of China (English)

    杜芳黎; 王宁; 张冬梅; 沈应中

    2010-01-01

    Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabilizer and dopant source,respectively.Structure and microstructure of the films were characterized with X-ray diffraction(XRD),field emission-scanning electron microscopy(FE-SEM) and the energy dispersive X-ray spectrometry(EDS).The infrared properties were also investigated.It was found that Ce-...

  2. Shape controlled Sn doped ZnO nanostructures for tunable optical emission and transport properties

    Directory of Open Access Journals (Sweden)

    T. Rakshit

    2013-11-01

    Full Text Available Pure and Sn doped ZnO nanostructures have been grown on SiO2/Si substrates by vapor-solid technique without using any catalysts. It has been found that the morphology of the nanostructures depend strongly on the growth temperature and doping concentration. By proper tuning of the growth temperature, morphology of pure ZnO can be changed from tetrapods to multipods. On the other hand, by varying the doping concentration of Sn in ZnO, the morphology can be tuned from tetrapods to flower-like multipods to nanowires. X-ray diffraction pattern reveals that the nanostructures have a preferred (0002 growth orientation, and they are tensile strained with the increase of Sn doping in ZnO. Temperature-dependent photoluminescence characteristics of these nanostructures have been investigated in the range from 10 to 300 K. Pure ZnO tetrapods exhibited less defect state emissions than that of pure ZnO multipods. The defect emission is reduced with low concentration of Sn doping, but again increases at higher concentration of doping because of increased defects. Transport properties of pure and Sn doped ZnO tetrapods have been studied using complex-plane impedance spectroscopy. The contribution from the arms and junctions of a tetrapod could be distinguished. Sn doped ZnO samples showed lower conductivity but higher relaxation time than that of pure ZnO tetrapods.

  3. The Antibacterial Activity of Ta-doped ZnO Nanoparticles.

    Science.gov (United States)

    Guo, Bing-Lei; Han, Ping; Guo, Li-Chuan; Cao, Yan-Qiang; Li, Ai-Dong; Kong, Ji-Zhou; Zhai, Hai-Fa; Wu, Di

    2015-12-01

    A novel photocatalyst of Ta-doped ZnO nanoparticles was prepared by a modified Pechini-type method. The antimicrobial study of Ta-doped ZnO nanoparticles on several bacteria of Gram-positive Bacillus subtilis (B. subtilis) and Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) were performed using a standard microbial method. The Ta-doping concentration effect on the minimum inhibitory concentration (MIC) of various bacteria under dark ambient has been evaluated. The photocatalytical inactivation of Ta-doped ZnO nanoparticles under visible light irradiation was examined. The MIC results indicate that the incorporation of Ta(5+) ions into ZnO significantly improve the bacteriostasis effect of ZnO nanoparticles on E. coli, S. aureus, and B. subtilis in the absence of light. Compared to MIC results without light irradiation, Ta-doped ZnO and pure ZnO nanoparticles show much stronger bactericidal efficacy on P. aeruginosa, E. coli, and S. aureus under visible light illumination. The possible antimicrobial mechanisms in Ta-doped ZnO systems under visible light and dark conditions were also proposed. Ta-doped ZnO nanoparticles exhibit more effective bactericidal efficacy than pure ZnO in dark ambient, which can be attributed to the synergistic effect of enhanced surface bioactivity and increased electrostatic force due to the incorporation of Ta(5+) ions into ZnO. Based on the antibacterial tests, 5 % Ta-doped ZnO is a more effective antimicrobial agent than pure ZnO.

  4. Photoluminescence of Eu (Ⅲ)-Doped ZnO Nanopowder and Energy Transfer from ZnO to Eu(Ⅲ) Ions

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lin-Li; GUO Chang-Xin; ZHAO Jun-Jing; HU Jun-Tao

    2005-01-01

    @@ An europium(Ⅲ)-doped ZnO (ZnO:Eu3+) nanopowder has been directly synthesized by a high-temperature calcination method. Under the typical UV ZnO excitation, Eua+-doped samples exhibit strong red luminescence from Eu3+ ions with complete quenching broad emission. An energy transfer from ZnO host to Eua+ ions can be observed.

  5. Explanation of ferromagnetism origin in C-doped ZnO by first principle calculations

    Energy Technology Data Exchange (ETDEWEB)

    El Amiri, A., E-mail: aelamiri@casablanca.ma [Laboratoire de Physique Fondamentale et Appliquée (LPFA), Faculté des Sciences Ain Chock, Université Hassan II, B.P. 5366 Mâarif, Casablanca, Maroc (Morocco); Lassri, H. [Laboratoire de Physique des Matériaux, Micro-électronique, Automatique et Thermique (LPMMAT). Faculté des Sciences Ain Chock, Université Hassan II, B.P. 5366 Mâarif, Casablanca, Maroc (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble (France); Abid, M. [Laboratoire de Physique Fondamentale et Appliquée (LPFA), Faculté des Sciences Ain Chock, Université Hassan II, B.P. 5366 Mâarif, Casablanca, Maroc (Morocco)

    2015-01-15

    By ab-initio calculations, we systematically study possible source of ferromagnetism C-doped ZnO compound. The electronic structure and magnetic properties of C-doped ZnO with / without ZnO host and C defects were investigated using the Korringa–Kohn–Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that Zn vacancy and presence of C defects (substitutional, interstitial or combination of both) induce the ferromagnetism in C-doped ZnO. From density of state (DOS) analysis, we show that p–p interaction between C atoms and/or C and O atoms is the mechanism of ferromagnetic coupling in C-doped ZnO. - Highlights: • We study the effect of ZnO host and C defects on ferromagnetism in C-doped ZnO. • Details of KKR method calculations performed to investigate both magnetic and electronic structures. • Magnetic moments, total and partial DOS for C-doped ZnO are well calculated and discussed. • Based on DOS calculations we interpret a origin of ferromagnetism in C-doped ZnO. • Mechanism of ferromagnetic coupling is well proposed.

  6. Anomalous antibacterial activity and dye degradation by selenium doped ZnO nanoparticles.

    Science.gov (United States)

    Dutta, Raj Kumar; Nenavathu, Bhavani Prasad; Talukdar, Soumita

    2014-02-01

    Selenium doped ZnO nanoparticles synthesized by mechanochemical method were spherically shaped of size distribution of 10.2±3.4 nm measured by transmission electron microscopy. Diffused reflectance spectroscopy revealed increase in the band gap, ranging between 3.47 eV and 3.63 eV due to Se doping in ZnO nanoparticles. The antibacterial activity of pristine and Se doped ZnO nanoparticles was attributed to ROS (reactive oxygen species) generation in culture media confirmed by TBARS assay. Compared to complete inhibition of growth by 0.45 mg/mL of pristine ZnO nanoparticles, the batches of 0.45 mg/mL of selenium doped ZnO nanoparticles exhibited only 51% inhibition of growth of Escherichia coli. The reduced antibacterial activity of selenium doped ZnO nanoparticles was attributed to two opposing factors, e.g., ROS generation for inhibition of growth, countered by sustaining growth of E. coli due to availability of Se micronutrients in culture media, confirmed by inductively coupled plasma mass spectrometer measurement. Higher ROS generation by selenium doped ZnO nanoparticles was attributed to creation of oxygen vacancies, confirmed from green emission peak observed at 565 nm. The impact of higher ROS generation by selenium doped ZnO nanoparticles was evident from enhanced photocatalytic degradation of trypan blue dye, than pristine ZnO nanoparticles.

  7. Morphology evolution of hydrothermally grown ZnO nanostructures on gallium doping and their defect structures

    Energy Technology Data Exchange (ETDEWEB)

    Pineda-Hernandez, G. [Facultad de Ingenieria Quimica, Benemerita Universidad Autonoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico); Escobedo-Morales, A., E-mail: alejandroescobedo@hotmail.com [Facultad de Ingenieria Quimica, Benemerita Universidad Autonoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico); Pal, U. [Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Apdo. Postal J-48, C.P. 72570 Puebla, Pue. (Mexico); Chigo-Anota, E. [Facultad de Ingenieria Quimica, Benemerita Universidad Autonoma de Puebla, C.P. 72570 Puebla, Pue. (Mexico)

    2012-08-15

    In the present article, the effect of gallium doping on the morphology, structural, and vibrational properties of hydrothermally grown ZnO nanostructures has been studied. It has been observed that incorporated gallium plays an important role on the growth kinetics and hence on the morphology evolution of the ZnO crystals. Ga doping in high concentration results in the contraction of ZnO unit cell, mainly along c-axis. Although Ga has high solubility in ZnO, heavy doping promotes the segregation of Ga atoms as a secondary phase. Incorporated Ga atoms strongly affect the vibrational characteristics of ZnO lattice and induce anomalous Raman modes. Possible mechanisms of morphology evolution and origin of anomalous Raman modes in Ga doped ZnO nanostructures are discussed. -- Highlights: Black-Right-Pointing-Pointer Ga doped ZnO nanostructures were successfully grown by hydrothermal chemical route. Black-Right-Pointing-Pointer Ga doping has strong effect on the resulting morphology of ZnO nanostructures. Black-Right-Pointing-Pointer Anomalous vibrational modes in wurtzite ZnO lattice are induced by Ga doping. Black-Right-Pointing-Pointer Incorporated Ga atoms accommodate at preferential lattice sites.

  8. Synthesis,Crystal Structural and Electrical Conductivity Properties of Fe-Doped Zinc Oxide Powders at High Temperatures

    Institute of Scientific and Technical Information of China (English)

    Hakan Colak; Orhan Trkoglu

    2012-01-01

    The synthesis,crystal structure and electrical conductivity properties of Fe-doped ZnO powders(in the range of 0.25-15 mol%) were reported in this paper.I-phase samples,which were indexed as single phase with a hexagonal(wurtzite) structure in the Fe-doped ZnO binary system,were determined by X-ray diffraction(XRD).The solubility limit of Fe in the ZnO lattice is 3 mol% at 950℃.The above mixed phase was observed.And the impurity phase was determined as the cubic-ZnFe 2 O 4 phase when compared with standard XRD data using the PDF program.This study focused on single I-phase ZnO samples which were synthesized at 950℃ because the limit of the solubility range is the widest at this temperature.The lattice parameters a and c of the I-phase decreased with Fe-doping concentration.The morphology of the I-phase samples was analyzed with a scanning electron microscope.The grain size of the I-phase samples increased with heat treatment and doping concentration.The electrical conductivity of the pure ZnO and single I-phase samples was investigated using the four-probe dc method at 100-950℃ in air atmosphere.The electrical conductivity values of pure ZnO,0.25 and 3 mol% Fe-doped ZnO samples at 100℃ were 2×10-6,1.7×10-3 and 6.3×10-4 S.cm-1,and at 950℃ they were 3.4,8.5 and 4 S.cm-1,respectively.

  9. Electron paramagnetic resonance in Cu-doped ZnO

    Science.gov (United States)

    Buchheit, R.; Acosta-Humánez, F.; Almanza, O.

    2016-04-01

    In this work, ZnO and Cu-doped ZnO nanoparticles (Zn1-xCuxO, x = 3%), with a calcination temperature of 500∘C were synthesized using the sol-gel method. The particles were analyzed using atomic absorption spectroscopy (AAS), X-ray diffraction (XRD) and electron paramagnetic resonance (EPR) at X-band, measurement in a temperature range from 90 K to room temperature. AAS confirmed a good correspondence between the experimental doping concentration and the theoretical value. XRD reveals the presence of ZnO phase in hexagonal wurtzite structure and a nanoparticle size for the samples synthesized. EPR spectroscopy shows the presence of point defects in both samples with g-values of g = 1.959 for shallow donors and g = 2.004 for ionized vacancies. It is important when these materials are required have been used as catalysts, as suggested that it is not necessary prepare them at higher temperature. A simulation of the Cu EPR signal using an anisotropic spin Hamiltonian was performed and showed good coincidence with the experimental spectra. It was shown that Cu2+ ions enter interstitial octahedral sites of orthorhombic symmetry in the wurtzite crystal structure. Temperature dependence of the EPR linewidth and signal intensity shows a paramagnetic behavior of the sample in the measurement range. A Néel temperature TN = 78 ± 19 K was determined.

  10. Al-doped and in-doped ZnO thin films in heterojunctions with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chabane, L.; Zebbar, N.; Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32-16111, Algiers (Algeria); Aida, M.S. [LCMet Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32-16111 Algiers (Algeria)

    2016-04-30

    The undoped, Al-doped and In-doped ZnO thin films were deposited by ultrasonic spray pyrolysis technique, onto glass and p-Si substrates and the physical properties of the films were investigated. The X-ray diffraction, optical analysis and electrical characterisations, indicate that the films were polycrystalline with hexagonal würtzite type structure and revealed that the aluminium doping deteriorates the crystalline and optical properties and enhances the electrical conductivity whereas indium doping improves all properties. The transport mechanism controlling the conduction through the heterojunctions was studied. For the heterostructures, the temperature dependent current–voltage characteristics showed rectifying behaviour in the dark, but current transport mechanism is not the same for all heterojunctions. Therefore, the presence of the interface states and volume defects are identified as limiting factors for obtaining a high quality heterojunction interface. - Highlights: • Al-doped and In-doped ZnO thin films have been deposited onto Si. • In-doped ZnO/p-Si heterojunction showed poor rectifying behaviour. • Al-doped ZnO/p-Si heterojunction showed a good rectifying at room temperature. • The carriers transport mechanisms was controlled by interfacial and volume defects.

  11. Structural and Magnetic Properties of Transition-Metal-Doped Zn 1-x Fe x O.

    Science.gov (United States)

    Abdel-Baset, T A; Fang, Yue-Wen; Anis, B; Duan, Chun-Gang; Abdel-Hafiez, Mahmoud

    2016-12-01

    The ability to produce high-quality single-phase diluted magnetic semiconductors (DMS) is the driving factor to study DMS for spintronics applications. Fe-doped ZnO was synthesized by using a low-temperature co-precipitation technique producing Zn 1-x Fe x O nanoparticles (x= 0, 0.02, 0.04, 0.06, 0.08, and 0.1). Structural, Raman, density functional calculations, and magnetic studies have been carried out in studying the electronic structure and magnetic properties of Fe-doped ZnO. The results show that Fe atoms are substituted by Zn ions successfully. Due to the small ionic radius of Fe ions compared to that of a Zn ions, the crystal size decreases with an increasing dopant concentration. First-principle calculations indicate that the charge state of iron is Fe (2+) and Fe (3+) with a zinc vacancy or an interstitial oxygen anion, respectively. The calculations predict that the exchange interaction between transition metal ions can switch from the antiferromagnetic coupling into its quasi-degenerate ferromagnetic coupling by external perturbations. This is further supported and explains the observed ferromagnetic bahaviour at magnetic measurements. Magnetic measurements reveal that decreasing particle size increases the ferromagnetism volume fraction. Furthermore, introducing Fe into ZnO induces a strong magnetic moment without any distortion in the geometrical symmetry; it also reveals the ferromagnetic coupling.

  12. Nanocluster formation in Co/Fe implanted ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Bharuth-Ram, K., E-mail: kbr@tlabs.ac.za [Durban University of Technology, Physics Department (South Africa); Masenda, H. [University of the Witwatersrand, School of Physics (South Africa); Doyle, T. B. [iThemba LABS (South Africa); Geburt, S.; Ronning, C. [University of Jena, Institute of Solid State Physics (Germany)

    2015-04-15

    Conversion electron Mössbauer Spectroscopy (CEMS) measurements were made on a ZnO single crystal sample implanted at room temperature (RT) with of 145 and 345 keV {sup 59}Co ions with respective fluences of 1.15×10{sup 16} ions/cm {sup 2} and 4.17×10{sup 16} ions/cm {sup 2}, followed by implantation of 60 keV {sup 57}Fe to a fluence of 0.50×10{sup 16}/cm {sup 2} to yield a ‘box-shaped’ implantation profile with a Co + Fe concentration of about 3.2 at. %. CEM spectra were collected after annealing the sample up to 973 K. The spectra after annealing up to 973 K are similar to spectra observed in other CEMS studies on Fe implanted ZnO, but show a dramatic change after the 973 K annealing step; it is dominated by a doublet component with fit parameters typical of Fe {sup 3+}. Magnetization curves of the sample after the 973 K anneal show hysteresis, with a small residual magnetization at RT that increases at 4 K. The saturation magnetization at 4 K was approximately 0.33 μ{sub B}/CoFe ion, in good agreement with observations for 5–8 nm sized Co nanoclusters in ZnO.

  13. Pure and Sn-doped ZnO films produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Holmelund, E.; Schou, Jørgen; Tougaard, S.;

    2002-01-01

    A new technique, metronome doping, has been used for doping of films during pulsed laser deposition (PLD). This technique makes it possible to dope continuously during film growth with different concentrations of a dopant in one deposition sequence. Films of pure and doped ZnO have been produced...

  14. Thermoelectric Properties of Al-Doped Mesoporous ZnO Thin Films

    Directory of Open Access Journals (Sweden)

    Min-Hee Hong

    2013-01-01

    Full Text Available Al-doped mesoporous ZnO thin films were synthesized by a sol-gel process and an evaporation-induced self-assembly process. In this work, the effects of Al doping concentration on the electrical conductivity and characterization of mesoporous ZnO thin films were investigated. By changing the Al doping concentration, ZnO grain growth is inhibited, and the mesoporous structure of ZnO is maintained during a relatively high temperature annealing process. The porosity of Al-doped mesoporous ZnO thin films increased slightly with increasing Al doping concentration. Finally, as electrical conductivity was increased as electrons were freed and pore structure was maintained by inhibiting grain growth, the thermoelectric property was enhanced with increasing Al concentration.

  15. Influence of nitrogen and magnesium doping on the properties of ZnO films

    Institute of Scientific and Technical Information of China (English)

    李东华; 陈晓航; 詹华瀚; 周颖慧; 康俊勇; 王惠琼; 周华; 李亚平; 黄政; 郑金成; 王嘉鸥; 钱海杰; 奎热西

    2016-01-01

    Undoped ZnO and doped ZnO films were deposited on the MgO(111) substrates using oxygen plasma-assisted molec-ular beam expitaxy. The orientations of the grown ZnO thin film were investigated by in situ refl ection high-energy electron diffraction and ex situ x-ray diffraction (XRD). The film roughness was measured by atomic force microscopy, which was correlated with the grain sizes determined by XRD. Synchrotron-based x-ray absorption spectroscopy was performed to study the doping effect on the electronic properties of the ZnO films, compared with density functional theory calculations. It is found that, nitrogen doping would hinder the growth of thin film, and generate the NO defect, while magnesium doping promotes the quality of nitrogen-doped ZnO films, inhibiting (N2)O production and increasing nitrogen content.

  16. Shape tunable synthesis of Eu- and Sm-doped ZnO microstructures: a morphological evaluation

    Indian Academy of Sciences (India)

    Gautam Sheel Thool; M Arunakumari; Ajaya Kumar Singh; Surya Prakash Singh

    2015-10-01

    Facile and low-cost aqueous chemical bath deposition route has been demonstrated to fabricate Eu- and Sm-doped ZnO microstructures. The effect of Eu and Sm ions on the morphology of the ZnO was investigated. The synthesized doped ZnO microstructures were systematically characterized by field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman and Fourier transform infrared spectra. FESEM images depicted the formation of Eu-doped ZnO microsphere and Sm-doped ZnO microplates. XRD spectra showed single crystalline nature of the undoped ZnO microdisks, whereas Eu- and Sm-doped ZnO exhibited the polycrystalline nature. The presence of Eu and Sm ions in the ZnO matrix was confirmed by XPS. This means that all the Eu ions substituted Zn2+ as Eu2+ into the ZnO matrix, whereas most of Sm ions were being in the trivalent state. This was probably due to the segregation of Sm2O3 species on the surface of ZnO microstructures.

  17. Tungsten-doped ZnO nanocomposite: Synthesis, characterization, and highly active photocatalyst toward dye photodegradation

    Energy Technology Data Exchange (ETDEWEB)

    Moafi, Hadi Fallah, E-mail: Fallah.m@guilan.ac.ir [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Rasht (Iran, Islamic Republic of); Zanjanchi, Mohammad Ali; Shojaie, Abdollah Fallah [Department of Chemistry, Faculty of Science, University of Guilan, P.O. Box 1914, Rasht (Iran, Islamic Republic of)

    2013-05-15

    A series of W-doped ZnO nanocomposite with different W contents were synthesized by sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) and BET surface area measurement. The XRD results revealed that all the W-doped samples showed a hexagonal wurtzite structure. The results of EDS and XPS revealed that W was doped into ZnO structure. The particle size of doped ZnO is much smaller as compared to that of pure ZnO. The photocatalytic activity of undoped ZnO and W-doped ZnO was evaluated by the photodegradation of methylene blue in aqueous solution. The results show that the photocatalytic activity of the W-doped ZnO is much higher than that of undoped ZnO and the optimum percentage of doped W is 4 mol%. The enhanced photocatalytic activity of the W-ZnO samples may be related to the narrowing of the band gap, increase in the charge separation efficiency, particle size reduction and increase of the surface area. Highlights: ► W-doped ZnO nanocomposites were synthesized by a sol–gel method. ► The XRD results revealed that all the materials consisting of wurtzite structure. ► The sizes of the W-ZnO nanocomposite are 5–10 nm, obtained from TEM image. ► With W doping into ZnO photoinduced charge separation rate has been enhanced. ► Photocatalytic activity of the W-ZnO is much higher than that of undoped ZnO.

  18. Influence of Co doping on combined photocatalytic and antibacterial activity of ZnO nanoparticles

    Science.gov (United States)

    Anandan, M.; Dinesh, S.; Krishnakumar, N.; Balamurugan, K.

    2016-11-01

    The present work aims to investigate the structural, optical, photocatalyst and antibacterial properties of bare and cobalt doped ZnO nanoparticles (NPs) with different concentrations Zn1-x Co x O (x = 0, 0.03, 0.06 and 0.09) synthesized by co-precipitation method. The XRD patterns confirmed that all samples of cobalt doped ZnO nanostructures revealed the formation of single phase having hexagonal wurtzite structure with crystallite size in the range of 31-41 nm. Further, the decreasing trend in lattice parameters and grain sizes were also seen with increasing doping concentrations which confirms the incorporation of Co ions into the ZnO lattice. This result was further supported by the FT-IR data. HR-TEM images demonstrated the distinct hexagonal like morphology with small agglomeration. The UV-visible absorption spectra exhibits red shift with increase in Co doping concentration in ZnO while corresponding bandgap energy of cobalt doped ZnO NPs decreased with increased Co doping concentration. PL spectra showed a weak UV and visible emission band which may be ascribed to the reduction in oxygen vacancy and defects by cobalt doping. XPS and EDX spectral results confirm the composition and the purity of Co doped ZnO NPs. Furthermore, the Co doped ZnO NPs were found to exhibit lesser photocatalytic activity for the degradation of methyl green dye under UV light illumination in comparison with the bare ZnO NPs. Moreover, anti-bacterial studies reveals that the Co doped ZnO NPs possess more antibacterial effect against gram positive Basillus subtills and gram negative Klebsiella pneumoniae bacterial strains than the bare ZnO NPs.

  19. Effect of oxygen vacancy defect on the magnetic properties of Co-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    Weng Zhen-Zhen; Zhang Jian-Min; Huang Zhi-Gao; Lin Wen-Xiong

    2011-01-01

    The influence of oxygen vacancy on the magnetism of Co-doped ZnO has been investigated by the first-principles calculations. It is suggested that oxygen vacancy and its location play crucial roles on the magnetic properties of Co-doped ZnO. The exchange coupling mechanism should account for the magnetism in Co-doped ZnO with oxygen vacancy and the oxygen vacancy is likely to be close to the Co atom. The oxygen vacancy (doping electrons) might be available for carrier mediation but is localized with a certain length and can strengthen the ferromagnetic exchange interaction between Co atoms.

  20. P-type nitrogen-doped ZnO nanostructures with controlled shape and doping level by facile microwave synthesis.

    Science.gov (United States)

    Herring, Natalie P; Panchakarla, Leela S; El-Shall, M Samy

    2014-03-04

    We report herein the development of a facile microwave irradiation (MWI) method for the synthesis of high-quality N-doped ZnO nanostructures with controlled morphology and doping level. We present two different approaches for the MWI-assisted synthesis of N-doped ZnO nanostructures. In the first approach, N-doping of Zn-poor ZnO prepared using zinc peroxide (ZnO2) as a precursor is carried out under MWI in the presence of urea as a nitrogen source and oleylamine (OAm) as a capping agent for the shape control of the resulting N-doped ZnO nanostructures. Our approach utilizes the MWI process for the decomposition of ZnO2, where the rapid transfer of energy directly to ZnO2 can cause an instantaneous internal temperature rise and, thus, the activation energy for the ZnO2 decomposition is essentially decreased as compared to the decomposition under conductive heating. In the second synthesis method, a one-step synthesis of N-doped ZnO nanostructures is achieved by the rapid decomposition of zinc acetate in a mixture of urea and OAm under MWI. We demonstrate, for the first time, that MWI decomposition of zinc acetate in a mixture of OAm and urea results in the formation of N-doped nanostructures with controlled shape and N-doping level. We report a direct correlation between the intensity of the Raman scattering bands in N-doped ZnO and the concentration of urea used in the synthesis. Electrochemical measurements demonstrate the successful synthesis of stable p-type N-doped ZnO nanostructures using the one-step MWI synthesis and, therefore, allow us to investigate, for the first time, the relationship between the doping level and morphology of the ZnO nanostructures. The results provide strong evidence for the control of the electrical behavior and the nanostructured shapes of ZnO nanoparticles using the facile MWI synthesis method developed in this work.

  1. Synthesis, microstructural characterization and optical properties of undoped, V and Sc doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Amezaga-Madrid, P.; Antunez-Flores, W.; Ledezma-Sillas, J.E.; Murillo-Ramirez, J.G.; Solis-Canto, O.; Vega-Becerra, O.E.; Martinez-Sanchez, R. [Centro de Investigacion en Materiales Avanzados S.C. and Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Chihuahua, Chih., C.P. 31109 (Mexico); Miki-Yoshida, M., E-mail: mario.miki@cimav.edu.mx [Centro de Investigacion en Materiales Avanzados S.C. and Laboratorio Nacional de Nanotecnologia, Miguel de Cervantes 120, Chihuahua, Chih., C.P. 31109 (Mexico)

    2011-06-15

    Research highlights: > Undoped, V and Sc doped ZnO thin films by Aerosol Assisted Chemical Vapour Deposition. > Optimum substrate temperatures of 673 K and 623 K for Sc and V doped films. > Around one third of the dopants in solution were deposited into the films. > Crystallite and grain size decreased with the increase of dopant concentration. > Optical band gap increased from 3.29 to 3.32 eV for undoped to 7 Sc/Zn at. %. - Abstract: Many semiconductor oxides (ZnO, TiO{sub 2}, SnO{sub 2}) when doped with a low percentage of non-magnetic (V, Sc) or magnetic 3d (Co, Mn, Ni, Fe) cation behave ferromagnetically. They have attracted a great deal of interest due to the integration of semiconducting and magnetic properties in a material. ZnO is one of the most promising materials to carry out these tasks in view of the fact that it is optically transparent and has n or p type conductivity. Here, we report the synthesis, microstructural characterization and optical properties of undoped, V and Sc doped zinc oxide thin films. ZnO based thin films with additions of V and Sc were deposited by the Aerosol Assisted Chemical Vapour Deposition method. V and Sc were incorporated separately in the precursor solution. The films were uniform, transparent and non-light scattering. The microstructure of the films was characterized by Grazing Incidence X-ray Diffraction, Scanning Electron Microscopy, and Scanning Probe Microscopy. Average grain size and surface rms roughness were estimated by the measurement of Atomic Force Microscopy. The microstructure of doped ZnO thin films depended on the type and amount of dopant material incorporated. The optical properties were determined from specular reflectance and transmittance spectra. Results were analyzed to determine the optical constant and band gap of the films. An increase in the optical band gap with the content of Sc dopant was obtained.

  2. Enhanced deposition of ZnO films by Li doping using radio frequency reactive magnetron sputtering

    Institute of Scientific and Technical Information of China (English)

    Liang-xian Chen; Sheng Liu; Cheng-ming Li; Yi-chao Wang; Jin-long Liu; Jun-jun Wei

    2015-01-01

    Radio frequency (RF) reactive magnetron sputtering was utilized to deposit Li-doped and undoped zinc oxide (ZnO) films on sili-con wafers. Various Ar/O2 gas ratios by volume and sputtering powers were selected for each deposition process. The results demonstrate that the enhanced ZnO films are obtained via Li doping. The average deposition rate for doped ZnO films is twice more than that of the un-doped films. Both atomic force microscopy and scanning electron microscopy studies indicate that Li doping significantly contributes to the higher degree of crystallinity of wurtzite–ZnO. X-ray diffraction analysis demonstrates that Li doping promotes the (002) preferential orien-tation in Li-doped ZnO films. However, an increase in the ZnO lattice constant, broadening of the (002) peak and a decrease in the peak inte-gral area are observed in some Li-doped samples, especially as the form of Li2O. This implies that doping with Li expands the crystal struc-ture and thus induces the additional strain in the crystal lattice. The oriented-growth Li-doped ZnO will make significant applications in fu-ture surface acoustic wave devices.

  3. Shape control of colloidal Mn doped ZnO nanocrystals and their visible light photocatalytic properties.

    Science.gov (United States)

    Yang, Yefeng; Li, Yaguang; Zhu, Liping; He, Haiping; Hu, Liang; Huang, Jingyun; Hu, Fengchun; He, Bo; Ye, Zhizhen

    2013-11-07

    For colloidal semiconductor nanocrystals (NCs), shape control and doping as two widely applied strategies are crucial for enhancing and manipulating their functional properties. Here we report a facile and green synthetic approach for high-quality colloidal Mn doped ZnO NCs with simultaneous control over composition, shape and optical properties. Specifically, the shape of doped ZnO NCs can be finely modulated from three dimensional (3D) tetrapods to 0D spherical nanoparticles in a single reaction scheme. The growth mechanism of doped ZnO NCs with interesting shape transition is explored. Furthermore, we demonstrate the tunable optical absorption features of Mn doped ZnO NCs by varying the Mn doping levels, and the enhanced photocatalytic performance of Mn doped ZnO NCs under visible light, which can be further optimized by delicately controlling their shapes and Mn doping concentrations. Our results provide an improved understanding of the growth mechanism of doped NCs during the growth process and can be potentially extended to ZnO NCs doped with other metal ions for various applications.

  4. Two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Linhua, E-mail: congyu3256@tom.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Zheng, Gaige; Zhao, Lilong; Pei, Shixin [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Optics and Photonic Technology Laboratory, Nanjing University of Information Science and Technology, Nanjing 210044 (China)

    2015-02-15

    Ag-doped ZnO thin films were prepared by a sol–gel method. The structural, morphological and optical properties of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis and photoluminescence spectra. The results show that the Ag in the ZnO thin films annealed at 500 °C for 1 h substitutes for Zn and exists in the form of Ag{sup +} ion (Ag{sub Zn}) while the Ag in the ZnO thin films without a post-annealing mainly exists in the form of simple substance (Ag{sup 0}). The incorporation of Ag indeed can improve the ultraviolet emission of ZnO thin films and suppress the visible emissions at the same time. However, the mechanisms on the ultraviolet emission enhancement in the annealed and unannealed Ag-doped ZnO thin films are very different. As for the post-annealed Ag-doped ZnO thin films, the UV emission enhancement maybe mainly results from more electron–hole pairs (excitons) due to Ag-doping while for the unannealed Ag-doped ZnO thin films; the UV emission enhancement is attributed to the resonant coupling between exciton emission in ZnO and localized surface plasmon in Ag nanoparticles. - Highlights: • Ag-doped ZnO thin films have been prepared by the sol–gel method. • Ag-doping can enhance ultraviolet emission of ZnO thin films and depress the visible emissions at the same time. • There are two different mechanisms on UV emission enhancement in Ag-doped ZnO thin films. • The UV emission enhancement from the resonant coupling between excitonic emissions and localized surface plasmon in Ag nanoparticle is very attractive.

  5. Effect of shallow donors on Curie–Weiss temperature of Co-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Shuxia, E-mail: gsx0391@sina.com [Department of Physics, Jiaozuo Teachers College, Jiaozuo 454001 (China); Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China); Li, Jiwu [Department of Physics, Jiaozuo Teachers College, Jiaozuo 454001 (China); Du, Zuliang [Key Laboratory for Special Functional Materials of Ministry of Education, Henan University, Kaifeng 475004 (China)

    2014-12-15

    Co-doped ZnO and Al, Co co-doped ZnO polycrystalline powders were synthesized by co-precipitation method. The magnetization curves measured at 2 K show no hysteresis neither remanence for all samples. ZnO:Co grown at low temperature has a positive Curie–Weiss temperature Θ, and ZnO:Co grown at high temperature has a negative Θ. But Al-doped ZnO:Co grown at high temperature has a positive Θ. Positive Curie–Weiss temperature Θ was considered to have relation to the presence of shallow donors in the samples. - Highlights: • Co-doped ZnO and Al, Co co-doped ZnO polycrystalline powders were synthesized. • No hysteresis is observed for all samples. • The Curie–Weiss temperature Θ changes its sign by Al doping. • Positive Θ should be related to shallow donors.

  6. Electronic and Magnetic Properties of Rare-Earth Metals Doped ZnO Monolayer

    Directory of Open Access Journals (Sweden)

    Changlong Tan

    2015-01-01

    Full Text Available The structural, electronic, and magnetic properties of rare-earth metals doped ZnO monolayer have been investigated using the first-principles calculations. The induced spin polarization is confirmed for Ce, Eu, Gd, and Dy dopings while the induced spin polarization is negligible for Y doping. The localized f states of rare-earth atoms respond to the introduction of a magnetic moment. ZnO monolayer undergoes transition from semiconductor to metal in the presence of Y, Ce, Gd, and Dy doping. More interestingly, Eu doped ZnO monolayer exhibits half-metallic behavior. Our result demonstrates that the RE-doping is an efficient route to modify the magnetic and electronic properties in ZnO monolayer.

  7. Highly active lanthanum doped ZnO nanorods for photodegradation of metasystox.

    Science.gov (United States)

    Korake, P V; Dhabbe, R S; Kadam, A N; Gaikwad, Y B; Garadkar, K M

    2014-01-05

    La-doped ZnO nanorods with different La contents were synthesized by microwave assisted method and characterized by various sophisticated techniques such as XRD, UV-Vis., EDS, XPS, SEM and TEM. The XRD patterns of the La-doped ZnO indicate hexagonal crystal structure with an average crystallite size of 30nm. It was found that the crystallite size of La-doped ZnO is much smaller as compared to pure ZnO and decreases with increasing La content. The photocatalytic activity of 0.5mol% La-doped ZnO in the degradation of metasystox was studied. It was observed that degradation efficiency of metasystox over La-doped ZnO increases up to 0.5mol% doping then decreases for higher doping levels. Among the catalyst studied, the 0.5mol% La-doped ZnO was the most active, showing high photocatalytic activity for the degradation of metasystox. The maximum reduction of concentration of metasystox was observed under static condition at pH 8. Reduction in the Chemical Oxygen Demand (COD) of metasystox was observed after 150min. The cytotoxicological studies of meristematic root tip cells of Allium cepa were studied. The results obtained indicate that photocatalytically degraded products of metasystox were less toxic as compared to metasystox.

  8. Conformal Al doped ZnO on rough silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Otto, Martin; Miclea, Paul T. [Martin-Luther-University Halle-Wittenberg, Institute of Physics, Heinrich Damerow Str. 4, 06120 Halle (Germany); Kroll, Matthias; Kaesebier, Thomas [Friedrich-Schiller-University Jena, Institute for Applied Physics, Max-Wien-Platz 1, 07743 Jena (Germany); Salzer, Roland [Fraunhofer Institute for Mechanics of Materials Halle IWM, Walter-Huelse-Str.1, 06120 Halle (Germany); Wehrspohn, Ralf B. [Martin-Luther-University Halle-Wittenberg, Institute of Physics, Heinrich Damerow Str. 4, 06120 Halle (Germany); Fraunhofer Institute for Mechanics of Materials Halle IWM, Walter-Huelse-Str.1, 06120 Halle (Germany)

    2011-07-01

    The feasibility of perfectly conformal deposition of transparent but highly conductive ZnO thin films on rough silicon surfaces for photovoltaic applications has been investigated. Aluminum doped zinc oxide (AZO) deposited via thermal ALD was used as a conformal cover layer for plasma etched black silicon. The coated structures achieve reflectances as low as 2.5% throughout the whole visible spectrum whereas the films exhibit resistivities of only 1.1.10{sup -3} {omega}cm. An absorption enhancement of nearly a factor of 10 at a wavelength of 1150 nm compared to a simulated perfect ARC was observed.

  9. Effect of Ga doping and point defect on magnetism of ZnO

    Science.gov (United States)

    Hou, Qingyu; Zhao, Chunwang; Jia, Xiaofang; Qu, Lingfeng

    2017-02-01

    The combined influence mechanism of Ga doping and Zn vacancy or O vacancy on magnetism of ZnO is studied using the first-principle calculation. The coexistence of Ga doping and Zn vacancy can achieve a Curie temperature higher than room temperature and the Ga doped ZnO system is a p-type diluted degenerate semiconductor with metalized ferromagnetism. The magnetism of the doping system of Ga doping and Zn vacancy is mainly contributed by double-exchange interaction through the holes of Zn vacancy taking carrier as medium. However, the system of Ga doping and O vacancy is non-magnetic. In the coexistence of Ga doping and Zn vacancy or O vacancy, a close relative distance between doping and vacancy will reduce the formation energy of the doping system but increase the easiness of doping and vacancy, as well as enhance the stability of the doping system.

  10. Effect of Ga doping and point defect on magnetism of ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Qingyu [College of Science, Inner Mongolia University of Technology, 010051 Hohhot (China); Zhao, Chunwang, E-mail: cwzhao@shmtu.edu.cn [College of Arts and Sciences, Shanghai Maritime University, 201306 Shanghai (China); Jia, Xiaofang; Qu, Lingfeng [College of Science, Inner Mongolia University of Technology, 010051 Hohhot (China)

    2017-02-01

    The combined influence mechanism of Ga doping and Zn vacancy or O vacancy on magnetism of ZnO is studied using the first-principle calculation. The coexistence of Ga doping and Zn vacancy can achieve a Curie temperature higher than room temperature and the Ga doped ZnO system is a p-type diluted degenerate semiconductor with metalized ferromagnetism. The magnetism of the doping system of Ga doping and Zn vacancy is mainly contributed by double-exchange interaction through the holes of Zn vacancy taking carrier as medium. However, the system of Ga doping and O vacancy is non-magnetic. In the coexistence of Ga doping and Zn vacancy or O vacancy, a close relative distance between doping and vacancy will reduce the formation energy of the doping system but increase the easiness of doping and vacancy, as well as enhance the stability of the doping system.

  11. Elaboration and characterization of Al doped ZnO nanorod thin films annealed in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Zhong Wenwu [Department of Physics, School of Physics and Nuclear Energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Liu Famin, E-mail: fmliu@buaa.edu.cn [Department of Physics, School of Physics and Nuclear Energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Cai Lugang; Peng Ding; Zhou Chuancang; Zeng Legui [Department of Physics, School of Physics and Nuclear Energy Engineering, Key Laboratory of Micro-nano Measurement-Manipulation and Physics (Ministry of Education), Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Liu Xuequan; Li Yi [Central Iron and Steel Research Institute, Beijing 100081 (China)

    2011-03-03

    Research highlights: > High transparent and conductive Al doped ZnO nanorod thin films were synthesized using sol-gel spin-coating method. > Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. > Crystal orientation of Al doped ZnO thin film has been raised. > Resistivity of films has been remarkably reduced by annealing in hydrogen. - Abstract: ZnO thin films doped with Al concentrations of 1.0, 2.0, 3.0, 4.0, 5.0 at% were prepared by a sol-gel spin-coating method on glass substrates and respectively annealed at 550 deg. C for 2 h in hydrogen and air. The X-ray diffraction and selected-area electron diffraction results confirm that the Al doped ZnO thin films are of wurtzite hexagonal ZnO. The scanning electron microscope results indicate that the Al doped ZnO nanorod thin films can be got by annealing in hydrogen rather than in air. The optical properties reveal that the Al doped ZnO thin films have obviously enhanced transmittance in the visible region. The electrical properties show that the resistivity of 1.0 at% Al doped ZnO thin films has been remarkably reduced from 0.73 {Omega} m by annealing in air to 3.2 x 10{sup -5} {Omega} m by annealing in hydrogen. It is originated that the Al doped ZnO nanorod thin films annealed in hydrogen increased in electron concentration and mobility due to the elimination of adsorbed oxygen species, and multicoordinated hydrogen.

  12. Local fields in Co and Mn Co-doped ZnO

    Science.gov (United States)

    Sato, W.; Kano, Y.; Suzuki, T.; Nakagawa, M.; Kobayashi, Y.

    2016-12-01

    The magnetic properties of ZnO co-doped with 5 at. % Co and 5 at. % Mn(Zn0.90Co0.05Mn0.05O) synthesized by a solid-state reaction were investigated by means of 57Co emission Mössbauer spectroscopy. The majority of the probe ions (80 %) residing in defect-free substitutional Zn sites take the oxidation state of 57Fe 2+, and the others presumably form local defects taking the state of 57Fe 3+ at room temperature. Both components show doublets, and RT ferromagnetism was thus absent in the sample. For the measurement at 10 K, spectral broadening was observed, implying a possible presence of a weak magnetic component.

  13. Influence of defects on electrical properties of electrodeposited co-doped ZnO nanocoatings

    Science.gov (United States)

    Simimol, A.; Anappara, Aji A.; Barshilia, Harish C.

    2017-01-01

    We present a systematic investigation of the electrical properties of undoped and Co-doped ZnO nanostructures at room temperature as an extensive study of the role of defects in ZnO. The ZnO nanostructures were fabricated by the electrodeposition method at low bath temperature (80 °C) and the Co concentration was varied from 0.01 to 0.2 mM. Electrical properties of the undoped and Co-doped ZnO nanostructures were studied in detail. The carrier concentration increases while the mobility reduces with increase in Co-concentration. The resistivity increases with an increase in Co-concentration and the reason is correlated with the defects in ZnO. In order to understand more details of the role of defects in the present I-V characteristic behavior of the Co-doped ZnO, high temperature vacuum annealing of ZnO sample was carried out. Electrical, optical and magnetic properties of the high temperature vacuum annealed ZnO were studied in detail. Photoluminescence spectroscopy (PL) results revealed more information of the defect levels which act as scattering centers for the carriers. Co-doping as well as annealing at high temperature in vacuum environment tunes the defects in ZnO and which influence the optical, magnetic and electrical behavior of the ZnO nanostructures.

  14. Highly Sensitive and Selective Ethanol Sensor Fabricated with In-Doped 3DOM ZnO.

    Science.gov (United States)

    Wang, Zhihua; Tian, Ziwei; Han, Dongmei; Gu, Fubo

    2016-03-02

    ZnO is an important n-type semiconductor sensing material. Currently, much attention has been attracted to finding an effective method to prepare ZnO nanomaterials with high sensing sensitivity and excellent selectivity. A three-dimensionally ordered macroporous (3DOM) ZnO nanostructure with a large surface area is beneficial to gas and electron transfer, which can enhance the gas sensitivity of ZnO. Indium (In) doping is an effective way to improve the sensing properties of ZnO. In this paper, In-doped 3DOM ZnO with enhanced sensitivity and selectivity has been synthesized by using a colloidal crystal templating method. The 3DOM ZnO with 5 at. % of In-doping exhibits the highest sensitivity (∼88) to 100 ppm ethanol at 250 °C, which is approximately 3 times higher than that of pure 3DOM ZnO. The huge improvement to the sensitivity to ethanol was attributed to the increase in the surface area and the electron carrier concentration. The doping by In introduces more electrons into the matrix, which is helpful for increasing the amount of adsorbed oxygen, leading to high sensitivity. The In-doped 3DOM ZnO is a promising material for a new type of ethanol sensor.

  15. Spectroscopic studies on photoelectron transfer from 2-(furan-2-yl)-1-phenyl-1H-phenanthro[9,10-d]imidazole to ZnO, Cu-doped ZnO and Ag-doped ZnO.

    Science.gov (United States)

    Thanikachalam, V; Arunpandiyan, A; Jayabharathi, J; Karunakaran, C; Ramanathan, P

    2014-09-01

    The 2-(furan-2-yl)-1-phenyl-1H-phenanthro[9,10-d]imidazole [FPI] has been designed and synthesized as fluorescent sensor for nanoparticulate ZnO. The present work investigates the photoelectron transfer (PET) from FPI to ZnO, Cu-doped ZnO and Ag- doped ZnO nanoparticles using electronic and life time spectral measurements. Broad absorption along with red shift indicates the formation of charge-transfer complex [FPI-Nanoparticles]. The photophysical studies indicate lowering of HOMO and LUMO energy levels of FPI on adsorption on ZnO due to FPI- ZnO interaction. The obtained binding constant implies that the binding of FPI with nanoparticles was influenced by the surface modification of ZnO nanoparticles with Cu and Ag.

  16. ZnO-doped LiFePO{sub 4} cathode material for lithium-ion battery fabricated by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yemin, E-mail: huyemin@shu.edu.cn [Laboratory for Microstructures/School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Yao, Jun; Zhao, Zhe; Zhu, Mingyuan; Ying Li,; Jin, Hongming [Laboratory for Microstructures/School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhao, Huijun [Centre for Clean Environment and Energy, Griffith School of Environment, Griffith University, Queensland 4222 (Australia); Wang, Jiazhao [Institute for Superconducting and Electronic Materials, Innovation Campus, University of Wollongong, NSW 2500 (Australia)

    2013-09-16

    LiFePO{sub 4} particles doped with zinc oxide was synthesized via a hydrothermal route and used as cathode material for lithium-ion battery. Sample of preferable shape and structure was obtained by a concise and efficient process. ZnO doping into the LiFePO{sub 4} matrix was positively confirmed by the results of X-ray diffraction (XRD); high-resolution transmission electron microscopy (HRTEM); energy dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). LiFePO{sub 4} doped with ZnO tends to form nanometer-size and homogeneous particles, which can improve markedly the performance and stability of charge-discharge cycle. A specific discharge capacity of ZnO-doped LiFePO{sub 4} at 132.3 mAh g{sup −1} was achieved, with 1.8% decrease after 100 cycles. Based on the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results, it has further shown that ZnO doping effectively reduces the impacts of polarization and transfer resistance during electrochemical processes. - Highlights: • Zinc source is added into LiFePO{sub 4} precursor in the form of Zn(OH){sub 2} solution. • ZnO help LiFePO{sub 4} form fine and even particles in the hydrothermal condition. • ZnO particles and Zn{sup 2+} ions act on the electrochemical performance of LiFePO{sub 4} together.

  17. Explanation of ferromagnetism origin in N-doped ZnO by first-principle calculations

    Indian Academy of Sciences (India)

    A El Amiri; H Lassri; E K Hlil; M Abid

    2016-02-01

    By $ab-initio$ calculations, the possible source of ferromagnetism in N-doped ZnO compound was systematically studied. The electronic structure and magnetic properties of N-doped ZnO with/without ZnO host and N defects were investigated using the Korringa–Kohn–Rostoker method combined with coherent potential approximation. It was shown that Zn vacancy and the presence of N defects (substitutional, interstitial or combination of both) induce the ferromagnetism in N-doped ZnO. From density of state analysis, it was shown that p–p interaction between 2p-elements (N,O) is the mechanism of ferromagnetic coupling in N-doped ZnO.

  18. High dielectric constant, low loss and high photocatalytic activity in Gd doped ZnO systems

    Science.gov (United States)

    Divya, N. K.; Pradyumnan, P. P.

    2017-01-01

    Enhanced photocatalytic activity and high dielectric constant values are achieved by gadolinium (Gd) doping in ZnO. The changes that happened to the wurtzite structure of ZnO on doping are depicted in detail by using x-ray diffraction spectroscopy. The chemical composition is confirmed using energy dispersive x-ray spectroscopy (EDAX). The influence of Gd incorporation in the emission spectra of ZnO is analysed from photoluminescence studies. The photocatalytic activity enhancement occurred in ZnO system on Gd doping was explored by kinetic rate analysis. The optimum incorporation of Gd has enhanced the dielectric constant value and decreased the loss of pristine. The high dielectric constant value and low loss make the system suitable for large scale of applications in microelectronics. The work also proposes large scale synthesis of highly efficient fluorescent Gd doped ZnO photocatalysts.

  19. ARTICLES: Synthesis and Characterization of TiO2 Doped ZnO Microtubes

    Science.gov (United States)

    Li, Yan

    2010-06-01

    The TiO2-doped ZnO microtubes have been successfully fabricated via a wet chemical method, using zinc chloride and titanium sulphate as the starting materials. The assynthesized products were characterized by X-ray diffraction, field emission scanning electron microscopy and room temperature photoluminescence measurement. The photocatalytic activity in degrading methyl orange was measured with a UV-Vis spectrophotometer. The pure ZnO microtubes exhibit an exact hexangular hollow structure with a diameter of about 700 nm, a length of 3 μm and a wall thickness of about 40 nm. The TiO2-doped ZnO microtubes with TiO2/ZnO ratio less than 5% have the same dimension with the pure ZnO microtubes, a smooth column shape, not a hexangular structure. The growth of ZnO may be inhibited by the more Ti4+ doped into ZnO structure to achieve a small dimension or a multiphase. The crystallinity of ZnO microtubes decreases with increasing TiO2 content, and then a multiphase containing ZnO, Ti3O5 and TiO occur when the TiO2/ZnO ratio is more than 5%. The UV emission intensity of the TiO2-doped ZnO obviously increases and then tends to decrease with TiO2/ZnO ratio increasing. The photocatalytic properties of the TiO2-doped ZnO microtubes are very efficient in degrading organic dyes of methyl orange and are well identical with its PL properties and the crystallinity.

  20. Microstructure, optical and electrical properties of Al-doped ZnO films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Su, Jianfeng, E-mail: sujianfengvy@gmail.com [Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Tang, Chunjuan; Niu, Qiang; Zang, Chunhe; Zhang, Yongsheng [Department of Mathematics and Physics, Luoyang Institute of Science and Technology, Luoyang 471023 (China); Fu, Zhuxi [Department of Physics, University of Science and Technology of China, Hefei 230026 (China)

    2012-09-01

    Highlights: Black-Right-Pointing-Pointer Al-doped ZnO films were grown on quartz substrates by MOCVD. Black-Right-Pointing-Pointer The preferred orientation of ZnO films decreased with the increase of Al content. Black-Right-Pointing-Pointer Decomposition products of TMA bringing down the surface activity of ZnO grains. Black-Right-Pointing-Pointer UV emission peak initially red-shifted and then blue-shifted as increasing Al content. Black-Right-Pointing-Pointer Low electrical resistivity of Al-doped ZnO films was obtained. - Abstract: Al-doped ZnO films were grown on quartz substrates by MOCVD. A systematical and detailed study about the effect of Al content on structural, optical and electrical properties were discussed. XRD measurements revealed that the preferred orientation of ZnO films decreased with the increase of Al content. AFM images indicated that the TMA molecules or their decomposition products bringing down the surface activity of ZnO grains, and so grain growth is inhibited. By the band tail states and the quantum confinement effect, the UV emission peak initially red-shifted and then blue-shifted. All Al-doped samples demonstrated more than 80% of the optical transparency in the visible region. Low electrical resistivity of Al-doped ZnO films was obtained. However, due to defects and grain boundary scattering which caused by Al doping, the hall mobility is increased initially and then decreased.

  1. Effect of Ag doping on structural, optical, and photocatalytic properties of ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, S.M.; Sarsari, I. Abdolhosseini, E-mail: abdolhosseini@cc.iut.ac.ir; Kameli, P.; Salamati, H.

    2015-08-15

    Highlights: • Hexagonal-wurtzite phase of ZnO were synthesized by thermal treatment of ball milled precursors at 400 °C. • Silver may be a good candidate for producing p-type ZnO. • Photocatalytic activity of ZnO nanoparticles increased by silver doping. • Reduction the optical energy gap of ZnO by silver doping is an advantage for use in optoelectronic devices. • The Ag 3d binding energy shifts to lower energies via XPS study. - Abstract: Silver-doped ZnO nanoparticles were successfully fabricated at 400 °C via a simple and rapid method based on short time solid state milling and calcination of precursor powders. The effect of Ag dilute doping on the structural, optical, and photocatalytic properties of ZnO nanoparticles was investigated by X-ray diffraction (XRD), UV–vis spectrophotometer and photoluminescence (PL) spectroscopy. X-ray analysis revealed that Ag doped ZnO solidified in hexagonal wurtzite structure. The intensity of deep level emission was reduced with increasing silver doping in PL measurement. The X-ray photoelectron spectroscopy (XPS) measurement predicted that Ag was mainly in the metallic state and ZnO was in the wurtzite structure. This metallic state accompanied by unique zinc oxide properties decolorized the methyl violet, efficiently. The first-principles calculation represented Ag deep level in ZnO with an n-type behavior, while in ZnO structure with grain boundary p-type nature via shallow states is dominant same as powder samples as studied in this present work. It was suggested that these Ag-doped ZnO nanoparticles may have good applications in optoelectronics, spintronics and wastewater treatment.

  2. Synthesis, structural and optical characterization of undoped, N-doped ZnO and co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pathak, Trilok Kumar, E-mail: tpathak01@gmail.com; Kumar, R.; Purohit, L. P., E-mail: proflppurohitphys@gmail.com [Semiconductor Research Lab., Department of Physics, Gurukula Kangri University, Haridwar (India)

    2015-05-15

    ZnO, N-doped ZnO and Al-N co-doped ZnO thin films were deposited on ITO coated corning glass by spin coater using sol-gel method. The films were annealed in air at 450°C for one hour. The crystallographic structure and morphology of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) respectively. The X-ray diffraction results confirm that the thin films are of wurtzite hexagonal with a very small distortion. The optical properties were investigated by transmission spectra of different films using spectrophotometer (Shimadzu UV-VIS-NIR 3600). The results indicate that the N doped ZnO thin films have obviously enhanced transmittance in visible region. Moreover, the thickness of the films has strong influences on the optical constants.

  3. Enhanced stability and photocatalytic performance of transition metal-doped ZnO with magnetite nanoparticle and zeolite

    Science.gov (United States)

    Pratiwi, M. I.; Afifah, N.; Saleh, R.

    2017-04-01

    The combination of zeolite and transition metal-doped ZnO nanoparticles for improved electron and hole photogeneration and inhibited electron-hole recombination, due to the trapping states, has been studied in our previous work. However, the photocatalyst has not been separated and reused after successfully degrading the organic dye. Therefore, in this study, we incorporated four different variations of magnetite nanoparticles into zeolite-supported Fe-doped ZnO, using the co-precipitation method. The samples were characterized with the aid of various measurements, such as x-ray diffraction, infrared absorption, diffuse reflectance spectroscopy, vibrating sample magnetometer (VSM), and Burneur-Emment-Teller (BET). The photocatalytic activity of nanocomposites was examined by photodegradation of methylene blue under UV light irradiation. The results show that the presence of a certain amount of magnetite nanoparticles in a zeolite-supported Fe-doped ZnO nanocomposite improved its efficiency in degrading methylene blue. The role of charged carriers and the active radical involved in the photocatalytic activity is discussed.

  4. Structural, morphological, optical, and magnetic properties of Gd-doped and (Gd, Mn) co-doped ZnO nanoparticles

    Science.gov (United States)

    Poornaprakash, B.; Chalapathi, U.; Babu, S.; Park, Si-Hyun

    2017-09-01

    Undoped, Gd doped, and (Gd, Mn) co-doped ZnO nanoparticles were fabricated via a hydrothermal method and their structural, morphological, optical, and magnetic properties were examined. X-ray diffraction and Raman spectroscopy studies confirmed that the Gd and Mn ions successfully entered the ZnO hexagonal lattice as substitute ions without changing the internal structure of the lattice. Morphology studies revealed that the synthesized nanoparticles were monodisperse and closely hexagonal shaped. The reflectance spectra showed a red shift of the absorption edge in both doped and co-doped samples. The diamagnetic ZnO sample was altered into a ferromagnetic material when doped with Gd ions, but this behavior was suppressed when Mn ions were co-doped into the matrix.

  5. Mn doped nanostucture ZnO thin film for photo sensor and gas sensor application

    Science.gov (United States)

    Mahajan, Sandip V.; Upadhye, Deepak S.; Shaikh, Shahid U.; Birajadar, Ravikiran B.; Siddiqui, Farha Y.; Ghule, Anil V.; Sharma, Ramphal

    2013-02-01

    Mn doped nanostructure ZnO thin film prepared by soft chemically route method. ZnO thin films were deposited on glass substrate by successive ionic layer adsorption and reaction technique (SILAR). After deposit ZnO thin film dipped in MnSO4 solution for 1 min. The optical properties as absorbance were determined using UV-Spectrophotometer and band gap was also calculated. The Structural properties were studied by XRD. The improvement in gas sensing properties was found to enhance after doping of Mn on ZnO thin film. The Photo Sensor nature was calculated by I-V characteristics.

  6. Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials

    OpenAIRE

    2015-01-01

    Band gap change in doped ZnO is an observed phenomenon that is very interesting from the fundamental point of view. This work is focused on the preparation of pure and single phase nanostructured ZnO and Cu as well as Mn-doped ZnO for the purpose of understanding the mechanisms of band gap narrowing in the materials. ZnO, Zn0.99Cu0.01O and Zn0.99Mn0.01O materials were prepared using a wet chemistry method, and X-ray diffraction (XRD) results showed that all samples were pure and single phase....

  7. Semiconducting properties of Al doped ZnO thin films.

    Science.gov (United States)

    Al-Ghamdi, Ahmed A; Al-Hartomy, Omar A; El Okr, M; Nawar, A M; El-Gazzar, S; El-Tantawy, Farid; Yakuphanoglu, F

    2014-10-15

    Aluminum doped ZnO (AZO) thin films were successfully deposited via spin coating technique onto glass substrates. Structural properties of the films were analyzed by X-ray diffraction, atomic force microscopy (AFM) and energy dispersive X-ray spectroscopy. X-ray diffraction results reveal that all the films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the direction (002) plane. The crystallite size of ZnO and AZO films was determined from Scherrer's formula and Williamson-Hall analysis. The lattice parameters of the AZO films were found to decrease with increasing Al content. Energy dispersive spectroscopy (EDX) results indicate that Zn, Al and O elements are present in the AZO thin films. The electrical conductivity, mobility carriers and carrier concentration of the films are increased with increasing Al doping concentration. The optical band gap (Eg) of the films is increased with increasing Al concentration. The AZO thin films indicate a high transparency in the visible region with an average value of 86%. These transparent AZO films may be open a new avenue for optoelectronic and photonic devices applications in near future.

  8. Atomic layer deposition of Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro [Department of Chemistry, Aalto University, FI-00076 Aalto (Finland); Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

    2013-01-15

    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al{sub 2}O{sub 3} on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al{sub 2}O{sub 3} phase and no further carrier doping of ZnO is observed.

  9. Optical and photocatalytic properties of Mn doped flower-like ZnO hierarchical structures

    Science.gov (United States)

    Ma, Qun; Lv, Xiangzhou; Wang, Yongqian; Chen, Jieyu

    2016-10-01

    A novel Mn doped flower-like ZnO hierarchical structures were successfully synthesized with a facile ion-exchange method. Structural properties of the synthesized photocatalysis have been investigated with XRD, FESEM equipped with energy dispersive spectroscopy, while UV-vis and PL spectroscopy were employed to study their optical properties. The inner structure of doped ZnO hierarchical structure can be finely transformed from nanosheets to nanorods and to nanoparticles with the increasing of doping contents. All the synthesized Mn/ZnO samples exhibit strong blue-violet emission. Furthermore, the optical absorption towards visible light of ZnO was significantly enhanced due to the incorporation of Mn ions. The photocatalytic results indicate that photocatalytic activity of ZnO was enhanced with the doping of Mn and there is an optimum Mn doping level, leading to the highest photocatalytic performance.

  10. Sustainable synthesis of metals-doped ZnO nanoparticles from zinc-bearing dust for photodegradation of phenol.

    Science.gov (United States)

    Wu, Zhao-Jin; Huang, Wei; Cui, Ke-Ke; Gao, Zhi-Fang; Wang, Ping

    2014-08-15

    A novel strategy of waste-cleaning-waste is proposed in the present work. A metals-doped ZnO (M-ZnO, M = Fe, Mg, Ca and Al) nanomaterial has been prepared from a metallurgical zinc-containing solid waste "fabric filter dust" by combining sulfolysis and co-precipitation processes, and is found to be a favorable photocatalyst for photodegradation of organic substances in wastewater under visible light irradiation. All the zinc and dopants (Fe, Mg, Ca and Al) for preparing M-ZnO are recovered from the fabric filter dust, without any addition of chemical as elemental source. The dust-derived M-ZnO samples deliver single phase indexed as the hexagonal ZnO crystal, with controllable dopants species. The photocatalytic activity of the dust-derived M-ZnO samples is characterized by photodegradation of phenol aqueous solution under visible light irradiation, giving more prominent photocatalytic behaviors than undoped ZnO. Such enhancements may be attributed to incorporation of the dust-derived metal elements (Fe, Mg, Ca and Al) into ZnO structure, which lead to the modification of band gap and refinement of grain size. The results show a feasibility to utilize the industrial waste as a resource of photodegradating organic substances in wastewater treatments.

  11. Ferromagnetism from Co-Doped ZnO Nanocantilevers above Room Temperature

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shao-Min; WANG Peng; LI Sheng; ZHANG Bin; GONG He-Chun; DU Zu-Liang

    2008-01-01

    @@ At low temperature (400° C), chemical vapour deposition (CVD) is employed to make comb-like Co-doped ZnO nanocantilever arrays (NAs). The magnetization curves of the as-synthesized Co-doped ZnO NAs indicate the existence of above-room-temperature ferromagnetism (ARTFM) (Curie temperature, Tc > 300 K) whereas un-doped ZnO NAs does not. The corresponding ferromagnetic source mechanism is discussed, in which defects play an important role due to the strong green light emission.

  12. Atomic layer deposition of Al-doped ZnO thin films

    OpenAIRE

    Tynell, Tommi; Yamauchi, Hisao; Karppinen, Maarit; Okazaki, Ryuji; Terasaki, Ichiro

    2013-01-01

    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al 2O3 on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up...

  13. Preparation, characterization and photocatalytic activity of Fe2O3/ZnO and Fe3O4/ZnO

    Directory of Open Access Journals (Sweden)

    Patij Shah

    2014-03-01

    Full Text Available Composite Iron oxide-Zinc oxide (α-Fe2O3/ZnO and Fe3O4/ZnO was synthesized by two step method. In the first step, uniform α-Fe2O3 and Fe3O4 particles were prepared through a hydrolysis process of ferric chloride at 80°C. In the second step, the ZnO particles were included in the α-Fe2O3 and Fe3O4 particles by a zinc acetate [Zn(Ac2·2H2O] assisted hydrothermal method at low temperature (90 °C. X-ray Powder Diffraction (XRD, Scanning Electron microscopy (SEM, Energy-dispersive X-ray spectroscopy (EDAX was used to study its structural properties. The α-Fe2O3 and ZnO phases were identified by XRD, energy dispersive X-ray analysis (EDAX. The photoactivities of α-Fe2O3/ZnO and Fe3O4/ZnO nanoparticles under UV irradiation were quantified by the degradation of formaldehyde. The determination of magnetic property was also carried out by Gouy balance method.

  14. Two-dimensional vanadium-doped ZnO nanosheet-based flexible direct current nanogenerator.

    Science.gov (United States)

    Gupta, Manoj Kumar; Lee, Ju-Hyuck; Lee, Keun Young; Kim, Sang-Woo

    2013-10-22

    Here, we report the synthesis of lead-free single-crystalline two-dimensional (2D) vanadium(V)-doped ZnO nanosheets (NSs) and their application for high-performance flexible direct current (DC) power piezoelectric nanogenerators (NGs). The vertically aligned ZnO nanorods (NRs) converted to NS networks by V doping. Piezoresponse force microscopy studies reveal that vertical V-doped ZnO NS exhibit typical ferroelectricity with clear phase loops, butterfly, and well-defined hysteresis loops with a piezoelectric charge coefficient of up to 4 pm/V, even in 2D nanostructures. From pristine ZnO NR-based NGs, alternating current (AC)-type output current was observed, while from V-doped ZnO NS-based NGs, a DC-type output current density of up to 1.0 μAcm(-2) was surprisingly obtained under the same vertical compressive force. The growth mechanism, ferroelectric behavior, charge inverted phenomena, and high piezoelectric output performance observed from the V-doped ZnO NS are discussed in terms of the formation of an ionic layer of [V(OH)4(-)], permanent electric dipole, and the doping-induced resistive behavior of ZnO NS.

  15. Synthesis of High Crystalline Al-Doped ZnO Nanopowders from Al2O3 and ZnO by Radio-Frequency Thermal Plasma

    Directory of Open Access Journals (Sweden)

    Min-Kyeong Song

    2015-01-01

    Full Text Available High crystalline Al-doped ZnO (AZO nanopowders were prepared by in-flight treatment of ZnO and Al2O3 in Radio-Frequency (RF thermal plasma. Micron-sized (~1 μm ZnO and Al2O3 powders were mixed at Al/Zn ratios of 3.3 and 6.7 at.% and then injected into the RF thermal plasma torch along the centerline at a feeding rate of 6.6 g/min. The RF thermal plasma torch system was operated at the plate power level of ~140 kVA to evaporate the mixture oxides and the resultant vapor species were condensed into solid particles by the high flow rate of quenching gas (~7000 slpm. The FE-SEM images of the as-treated powders showed that the multipod shaped and the whisker type nanoparticles were mainly synthesized. In addition, these nanocrystalline structures were confirmed as the single phase AZO nanopowders with the hexagonal wurtzite ZnO structure by the XRD patterns and FE-TEM results with the SAED image. However, the composition changes of 0.3 and 1.0 at.% were checked for the as-synthesized AZO nanopowders at Al/Zn ratios of 3.3 and 6.7 at.%, respectively, by the XRF data, which can require the adjustment of Al/Zn in the mixture precursors for the applications of high Al doping concentrations.

  16. Using the hydrothermal method to grow p-type ZnO nanowires on Al-doped ZnO thin film to fabricate a homojunction diode.

    Science.gov (United States)

    Tseng, Yung-Kuan; Hung, Meng-Chun; Su, Shun-Lung; Li, Sheng-Kai

    2014-10-01

    In this study, the hydrothermal method is used to grow phosphorus-doped ZnO nanowires on Si/SiO2 substrates deposited with Al-doped ZnO thin film. This structure forms a homogeneous p-n junction. In this study, we are the pioneers to use ammonium hypophosphite (NH4H2PO2) as a source of phosphorus to prepare the precursor solution. Ammonium hypophosphite of different concentration levels is used to observe its effects on the growth of nanowires. The results show that the precursor solution prepared from ammonium hypophosphite can produce good crystalline ZnO nanowires while there is no linear relationship between the amounts and concentration levels of phosphorus doped into the nanowires. Whether the phosphorus-doped ZnO nanowires have the characteristics of a p-type semiconductor is indirectly verified by measuring whether the p-n junction made up of Al-doped ZnO thin film and phosphorus-doped ZnO nanowires shows rectifying behavior. I-V measurements are made on the specimens. The results show good rectifying behavior, proving that the phosphorus-doped ZnO nanowires and Al-doped AZO films have p-type and n-type semiconductor properties, constituting a good p-n junction. This result also proves that ammonium hypophosphite is a better source of phosphorus in the hydrothermal method to synthesize phosphorus-doped ZnO nanowires.

  17. Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: Optical and electrochemical properties

    Science.gov (United States)

    Romeiro, Fernanda C.; Marinho, Juliane Z.; Lemos, Samantha C. S.; de Moura, Ana P.; Freire, Poliana G.; da Silva, Luis F.; Longo, Elson; Munoz, Rodrigo A. A.; Lima, Renata C.

    2015-10-01

    We report for the first time a rapid preparation of Zn1-2xCoxNixO nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green-orange-red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO.

  18. Experimental Studies on Doped and Co-Doped ZnO Thin Films Prepared by RF Diode Sputtering

    OpenAIRE

    2009-01-01

    Our research on the growing and characterizing of p-type ZnO thin films, prepared by radio frequency (RF) diode sputtering, mono-doped with nitrogen, and co-doped with aluminium and nitrogen, is a response of the need from p-type ZnO thin films for device applications. The dopants determine the conductivity type of the film and its physical properties. We obtained p-type ZnO thin films by RF diode sputtering and using a nitrogen dopant source. The novelty in our approach is in the use of a pl...

  19. Percentage of different aluminum doping influence the morphological and optical properties of ZnO nanostructured growth for sensor application

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R., E-mail: ruziana12@gmail.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang (Malaysia); Ismail, A. S., E-mail: kyrin-samaxi@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z., E-mail: Zurai142@salam.uitm.edu.my [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Mamat, M. H., E-mail: hafiz-030@yahoo.com [NANO-ElecTronic Centre, Faculty of Electrical engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Alrokayan, Salman A. H., E-mail: dr.salman@alrokayan.com; Khan, Haseeb A., E-mail: khan-haseeb@yahoo.com [Department of Biochemistry, College of Science, King Saud University (KSU), Riyadh 11451 (Saudi Arabia); Rusop, M., E-mail: nanouitm@gmail.com [NANO-SciTech Centre, Institue of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA Pahang, 26400 Bandar Tun Razak Jengka, Pahang (Malaysia)

    2016-07-06

    In this work, Zinc Oxide (ZnO) with different aluminum (Al) doping percentage was synthesis by sol gel immersion method. Al doped ZnO at various doping percentage from 1, 2, 3, 4 and 5. It was found that with different Al percentage influence the morphological and optical properties of ZnO growth. Field Emission Scanning Electron Microscope (FESEM) image showed the use of different Al doping causes the difference in geometry and size of ZnO nanorods growth. Based on UV-Vis spectroscopy, the transmittance at 1% Al doping has the highest spectrum.

  20. Effect of doping concentration on absorbance, structural, and magnetic properties of cobalt-doped ZnO nano-crystallites

    Science.gov (United States)

    Shafique, Muhammad Ahsan; Shah, Saqlain A.; Nafees, Muhammad; Rasheed, Khalid; Ahmad, Riaz

    2012-10-01

    Controlled conduction of magnetic spins is desired for data processing in modern spintronic devices. Transition metal-doped ZnO is a potential candidate for this purpose. We studied the effects of cobalt doping on structural, absorbance, and magnetic properties of ZnO nano-particles. Different compositions (Zn0.99Co0.1O, Zn0.97Co0.3O, and Zn0.95Co0.5O) of cobalt-doped ZnO were fabricated using metallic chlorides by co-precipitation method. XRD revealed standard ZnO wurtzite crystal structure without lattice distortion due to impurities but showed presence of additional phases at higher doping ratios. Fourier transformed infrared spectroscopy also confirmed the standard ZnO profiles at lower doping ratios but additional phases at higher doping. Vibrating sample magnetometer showed soft ferromagnetic behavior for low impurity samples and harder ferromagnetic behavior for higher doping at room temperature. A simultaneous differential scanning calorimetry/thermo gravimetric analysis was performed to study the phase variations during crystallization.

  1. Transition-metal-doped ZnO nanoparticles: synthesis, characterization and photocatalytic activity under UV light.

    Science.gov (United States)

    Saleh, Rosari; Djaja, Nadia Febiana

    2014-09-15

    ZnO nanoparticles doped with transition metals (Mn and Co) were prepared by a co-precipitation method. The synthesized nanoparticles were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-rays, Fourier transform infrared spectroscopy, electron spin resonance spectroscopy and diffuse reflectance spectroscopy. The photocatalytic activities of the transition-metal-doped ZnO nanoparticles were evaluated in the degradation of methyl orange under UV irradiation. ZnO nanoparticles doped with 12 at.% of Mn and Co ions exhibited the maximum photodegradation efficiency. The experiment also demonstrated that the photodegradation efficiency of Mn-doped ZnO nanoparticles was higher than that of Co-doped ZnO nanoparticles. These results indicate that charge trapping states due to the doping were the decisive factor rather than the average particle size and energy gap. Moreover the effect of pH values on the degradation efficiency was discussed in the photocatalytic experiments using 12 at.% Mn- and Co-doped ZnO nanoparticles.

  2. Electronic structure, magnetic and structural properties of Ni doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Shalendra, E-mail: shailuphy@gmail.com [School of Materials Science and Engineering, Changwon National University, 9 Sarim dong, Changwon 641 773 (Korea, Republic of); Vats, Prashant [Material Science Research Laboratory, Department of Physics, S. V. College, Aligarh 202001, Uttar Pradesh (India); Gautam, S. [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Gupta, V.P.; Verma, K.D. [Material Science Research Laboratory, Department of Physics, S. V. College, Aligarh 202001, Uttar Pradesh (India); Chae, K.H. [Advanced Analysis Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Hashim, Mohd [Department of Applied Physics, Aligarh Muslim University, Aligarh 202-002 (India); Choi, H.K., E-mail: hkchoi99@changwon.ac.kr [Department of Mechatronics Convergence, College of Engineering, Changwon National University, Changwon 641 773 (Korea, Republic of)

    2014-11-15

    Highlights: • XRD, and HR-TEM results show the single phase nature of Ni doped ZnO nanoparticles. • dc magnetization results indicate the RT-FM in Ni doped ZnO nanoparticles. • Ni L{sub 3,2} edge NEXAFS spectra infer that Ni ions are in +2 valence state. • O K edge NEXAFS spectra show that O vacancy increases with Ni doping in ZnO. - Abstract: We report structural, magnetic and electronic structural properties of Ni doped ZnO nanoparticles prepared by auto-combustion method. The prepared nanoparticles were characterized by using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and dc magnetization measurements. The XRD and HR-TEM results indicate that Ni doped ZnO nanoparticles have single phase nature with wurtzite lattice and exclude the presence of secondary phase. NEXAFS measurements performed at Ni L{sub 3,2}-edges indicates that Ni ions are in +2 valence state and exclude the presence of Ni metal clusters. O K-edge NEXAFS spectra indicate an increase in oxygen vacancies with Ni-doping, while Zn L{sub 3,2}-edge show the absence of Zn-vacancies. The magnetization measurements performed at room temperature shows that pure and Ni doped ZnO exhibits ferromagnetic behavior.

  3. An aqueous solution-based doping strategy for large-scale synthesis of Sb-doped ZnO nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fei; Bayerl, Dylan; Shi Jian; Wang Xudong [Department of Materials Science and Engineering, University of Wisconsin at Madison (United States); Seo, Jung-Hun; Mi Hongyi; Ma Zhenqiang [Department of Electrical and Computer Engineering, University of Wisconsin at Madison (United States); Zhao Deyin; Shuai Yichen; Zhou Weidong, E-mail: xudong@engr.wisc.edu [Department of Electrical Engineering, University of Texas at Arlington (United States)

    2011-06-03

    An aqueous solution-based doping strategy was developed for controlled doping impurity atoms into a ZnO nanowire (NW) lattice. Through this approach, antimony-doped ZnO NWs were successfully synthesized in an aqueous solution containing zinc nitrate and hexamethylenetetramine with antimony acetate as the dopant source. By introducing glycolate ions into the solution, a soluble antimony precursor (antimony glycolate) was formed and a good NW morphology with a controlled antimony doping concentration was successfully achieved. A doping concentration study suggested an antimony glycolate absorption doping mechanism. By fabricating and characterizing NW-based field effect transistors (FETs), stable p-type conductivity was observed. A field effect mobility of 1.2 cm{sup 2} V{sup -1} s{sup -1} and a carrier concentration of 6 x 10{sup 17} cm{sup -3} were achieved. Electrostatic force microscopy (EFM) characterization on doped and undoped ZnO NWs further illustrated the shift of the metal-semiconductor barrier due to Sb doping. This work provided an effective large-scale synthesis strategy for doping ZnO NWs in aqueous solution.

  4. Enhanced photovoltaic performance of quantum dot-sensitized solar cell fabricated using Al-doped ZnO nanorod electrode

    Science.gov (United States)

    Raja, M.; Muthukumarasamy, N.; Velauthapillai, Dhayalan; Balasundrapraphu, R.; Senthil, T. S.; Agilan, S.

    2015-04-01

    ZnO and Al doped ZnO nanorods have been successfully synthesized on ITO substrate via solgel dip coating method without using any catalyst. The X-ray diffraction studies showed that the Al doped ZnO samples are of hexagonal wurtzite structure. The Al ions were successfully incorporated into the ZnO lattice. Scanning electron microscopy images reveal that the average diameter of ZnO nanorods and Al doped ZnO nanorods are ∼300 nm and ∼200 nm respectively. The energy dispersive X-ray (EDS) analysis confirmed the presence Al in the ZnO thin films. The CdS quantum dot sensitized Al doped ZnO solar cell exhibited a power conversion efficiency of 1.5%.

  5. Al-Doped ZnO Monolayer as a Promising Transparent Electrode Material: A First-Principles Study

    Directory of Open Access Journals (Sweden)

    Mingyang Wu

    2017-03-01

    Full Text Available Al-doped ZnO has attracted much attention as a transparent electrode. The graphene-like ZnO monolayer as a two-dimensional nanostructure material shows exceptional properties compared to bulk ZnO. Here, through first-principle calculations, we found that the transparency in the visible light region of Al-doped ZnO monolayer is significantly enhanced compared to the bulk counterpart. In particular, the 12.5 at% Al-doped ZnO monolayer exhibits the highest visible transmittance of above 99%. Further, the electrical conductivity of the ZnO monolayer is enhanced as a result of Al doping, which also occurred in the bulk system. Our results suggest that Al-doped ZnO monolayer is a promising transparent conducting electrode for nanoscale optoelectronic device applications.

  6. Al-Doped ZnO Monolayer as a Promising Transparent Electrode Material: A First-Principles Study.

    Science.gov (United States)

    Wu, Mingyang; Sun, Dan; Tan, Changlong; Tian, Xiaohua; Huang, Yuewu

    2017-03-29

    Al-doped ZnO has attracted much attention as a transparent electrode. The graphene-like ZnO monolayer as a two-dimensional nanostructure material shows exceptional properties compared to bulk ZnO. Here, through first-principle calculations, we found that the transparency in the visible light region of Al-doped ZnO monolayer is significantly enhanced compared to the bulk counterpart. In particular, the 12.5 at% Al-doped ZnO monolayer exhibits the highest visible transmittance of above 99%. Further, the electrical conductivity of the ZnO monolayer is enhanced as a result of Al doping, which also occurred in the bulk system. Our results suggest that Al-doped ZnO monolayer is a promising transparent conducting electrode for nanoscale optoelectronic device applications.

  7. Enhanced UV absorbance and photoluminescence properties of ultrasound assisted synthesized gold doped ZnO nanorods

    Science.gov (United States)

    Sahu, Dojalisa; Panda, N. R.; Acharya, B. S.; Panda, A. K.

    2014-06-01

    Au doped ZnO (ZnO:Au) nanostructures were synthesized by ultrasound assisted wet chemical method. The concentration of dopant was varied and both structural and optical properties of ZnO:Au were investigated. The crystal structure and morphology of the samples were examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). These results showed the formation of nanorods of ZnO:Au having wurtzite structure and c-axis orientation. Gradual increase in crystallite size and bond length was also observed with the increase in gold concentration in ZnO intending the expansion of lattice after gold doping. The optical absorption measurements showed high ultraviolet (UV) absorbance property of ZnO:Au with sharp and intense absorption band in this region as compared to pristine ZnO. Photoluminescence (PL) measurements showed excitonic emission band of ZnO around 390 nm for both undoped and Au doped ZnO nanoparticles. Further, a strong emission around 467 nm was observed in the PL spectra of ZnO/ZnO:Au which was attributed to the transitions related to excess of oxygen vacancies. Interestingly, a new band was observed at 582 nm for doped ZnO samples which grew in intensity with doping concentration. This band was ascribed to the gold nanoparticle adsorbed on the surface of ZnO.

  8. Mn2+ ions distribution in doped sol-gel deposited ZnO films

    Science.gov (United States)

    Stefan, Mariana; Ghica, Daniela; Nistor, Sergiu V.; Maraloiu, Adrian V.; Plugaru, Rodica

    2017-02-01

    The localization and distribution of the Mn2+ ions in two sol-gel deposited ZnO films doped with different manganese concentrations were investigated by electron paramagnetic resonance spectroscopy and analytical transmission electron microscopy. In the lightly doped sample the Mn2+ ions are mainly localized substitutionally at isolated tetrahedrally coordinated Zn2+ sites in both crystalline ZnO nanograins (34%) and surrounding disordered ZnO (52%). In the highly doped ZnO film, a much smaller proportion of manganese substitutes Zn2+ in the crystalline and disordered ZnO (10%). The main amount (85%) of manganese aggregates in a secondary phase as an insular-like distribution between the ZnO nanograins. The remaining Mn2+ ions (14% and 5% at low and high doping levels, respectively) are localized at isolated, six-fold coordinated sites, very likely in the disordered intergrain region. Annealing at 600 °C induced changes in the Mn2+ ions distribution, reflecting the increase of the ZnO crystallization degree, better observed in the lightly doped sample.

  9. Enhanced Gas Sensing Properties of Spin-coated Na-doped ZnO Nanostructured Films

    Science.gov (United States)

    Basyooni, Mohamed A.; Shaban, Mohamed; El Sayed, Adel M.

    2017-01-01

    In this report, the structures, morphologies, optical, electrical and gas sensing properties of ZnO and ZnO: Na spin-coated films are studied. X-ray diffraction (XRD) results reveal that the films are of a single phase wurtzite ZnO with a preferential orientation along (002) direction parallel to c-axis. Na doping reduces the crystalline quality of the films. The plane surface of ZnO film turned to be wrinkle net-work structure after doping. The reflectance and the optical band gap of the ZnO film decreased after Na doping. The wrinkle net-work nanostructured Na-doped film shows an unusually sensitivity, 81.9% @ 50 sccm, for CO2 gas at room temperature compared to 1.0% for the pure ZnO film. The signals to noise ratio (SNR) and detection limit of Na-doped ZnO sensor are 0.24 and 0.42 sccm, respectively. These enhanced sensing properties are ascribed to high surface-to-volume ratio, hoping effect, and the increase of O- vacancies density according to Kroger VinK effect. The response time increased from 179 to 240 s by the incorporation of Na atoms @50 sccm. This response time increased as the CO2 concentration increased. The recovery time is increased from 122 to 472 s by the incorporation of Na atoms @50 sccm. PMID:28145506

  10. Effect of nitrogen doping on structural and optical properties of ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Renu Kumari

    2015-08-01

    Full Text Available Influence of nitrogen doping on structural and optical properties of ZnO nanoparticles has been studied. Undoped and N doped ZnO nanoparticles were synthesized via chemical precipitation approach. The prepared samples were characterized through X-ray diffraction (XRD, Transmission electron microscopy (TEM equipped with Energy dispersive X-ray (EDAX spectroscopy, UV–visible spectroscopy, Fourier transform infrared (FTIR spectroscopy and micro-Raman spectroscopy (µRS. Wurtzite phase of undoped as well as 0.5–10% N doped ZnO nanoparticles was confirmed through characteristic XRD patterns. The particle size expansion due to N incorporation in ZnO was further revealed by TEM and EDAX analysis where 11 nm size undoped and 18–22 nm size 0.5–10% N doped ZnO (N:ZnO nanoparticles without any impurity were ascertained. Slight blue-shift in band gap energy, as observed in our case, symbolized weak quantum confinement of the prepared nanoparticles. The alterations in vibrational modes of ZnO due to N incorporation, remarkably H substituting at O site and subsequently causing the passivation in N:ZnO nanoparticles, were detected through FTIR analysis. Finally, the effect of the nano-size of crystallite and gradual prominence of N into ZnO lattice due to increase of N doping concentration in prepared nanoparticles was meticulously expatiated though µRS analysis.

  11. Effect of nitrogen doping on structural and optical properties of ZnO nanoparticles

    Institute of Scientific and Technical Information of China (English)

    Renu Kumari; Anshuman Sahai; Navendu Goswami

    2015-01-01

    Influence of nitrogen doping on structural and optical properties of ZnO nanoparticles has been studied. Undoped and N doped ZnO nanoparticles were synthesized via chemical precipitation approach. The prepared samples were characterized through X-ray diffraction (XRD), Transmission electron microscopy (TEM) equipped with Energy dispersive X-ray (EDAX) spectroscopy, UV–visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and micro-Raman spectroscopy (mRS). Wurtzite phase of undoped as well as 0.5–10% N doped ZnO nanoparticles was confirmed through characteristic XRD patterns. The particle size expansion due to N incorporation in ZnO was further revealed by TEM and EDAX analysis where 11 nm size undoped and 18–22 nm size 0.5–10%N doped ZnO (N:ZnO) nanoparticles without any impurity were ascertained. Slight blue-shift in band gap energy, as observed in our case, symbolized weak quantum confinement of the prepared nanoparticles. The alterations in vibrational modes of ZnO due to N incorporation, remarkably H substituting at O site and subsequently causing the passivation in N:ZnO nanoparticles, were detected through FTIR analysis. Finally, the effect of the nano-size of crystallite and gradual prominence of N into ZnO lattice due to increase of N doping concentration in prepared nanoparticles was meticulously expatiated though mRS analysis.

  12. Synthesis, physical properties and catalytic activity of Cr-doped ZnO nanoparticles

    Science.gov (United States)

    Djaja, Nadia Febiana; Noorhidayati, Annisa; Saleh, Rosari

    2016-03-01

    The present work studies the photocatalytic degradation of Cr-doped ZnO nanoparticles toward aqueous mixture of organic dyes, such as methyl orange, methylene blue and congo red. Cr-doped ZnO nanoparticles were synthesized using co-precipitation method and characterized by several method of measurements. Photocatalytic mechanism was investigated by measuring the photocatalytic degradation rate in the presence of scavenger. The results revealed that hydroxyl radical plays an important role in photocatalytic activity.

  13. Synthesis and properties of Ag-doped ZnO films with room temperature ferromagnetism

    Science.gov (United States)

    Xu, Qin; Wang, Zhi-Jun; Chang, Ze-Jiang; Liu, Jing-Jin; Ren, Ya-Xuan; Sun, Hui-Yuan

    2016-12-01

    A series of Ag-doped ZnO films were prepared by DC magnetron sputtering. XRD and SEM results showed that the doping amount of Ag had a great influence on the films' morphology and ferromagnetism, and their magnetism can be improved by doping an appropriate amount of Ag. The theoretical analysis suggested that the magnetism resulted mainly from the film grain boundary surfaces. Further research revealed that these films had strong timeliness. Such a result indicated that the room temperature ferromagnetism of Ag-doped ZnO films did not stem from the cation vacancies but from the oxygen vacancies on the boundary surfaces.

  14. Characterization and Properties Evaluation of Conducting Al – doped ZnO at low temperature by ECD Method

    Directory of Open Access Journals (Sweden)

    Harish Chevva

    2015-06-01

    Full Text Available Low temperature (70°C deposition of Al-doped ZnO films are successfully reported by simple electrochemical deposition technique. Simple three electrode setup is used with chemical bath containing different molar ratios of Zinc nitrate and Aluminium nitrate (9:1, 8:2, 7:3 and 6:4, a constant potential of -1.3 V is employed between electrodes for deposition of films. ‘2θ’ and‘d’ spacing variations obtained from XRD with varied Al content proves doping of Al into crystal structure of ZnO. Al content from Elemental analysis (EDAX is in accordance with the compositions used. Morphology of films is characterized by FE-SEM, where flake-like structures are observed. Variation of Electrical resistivity with varying Al content in the films supports the argument of doping. Lowest resistivity is observed for composition 7:3 i.e. 2.25x10-4 Ω cm. Optical characterization is done on the film powder for measuring band gap and transmittance, which showed 90% of transmittance and Band gap widening is observed for different compositions, due to incorporation of Al into crystal structure of ZnO

  15. Fabrication of ZnO Bi-crystals with twist boundaries using Co doped ZnO single crystals

    CERN Document Server

    Ohashi, N; Ohgaki, T; Tsurumi, T; Fukunaga, O; Haneda, H; Tanaka, J

    1999-01-01

    Zn O single crystals doped with Co were grown by using a flux method and their electrical properties were investigated by Hall effect. Then, these crystals were polished with diamond paste and bonded to form bi-crystal by hot pressing under a pressure of 10 MPa at 1000 .deg. C. The bi-crystals showed nonlinear I-V curves, and the curvature of I-V relation agreed with that for Co-doped polycrystalline ZnO.

  16. Defect mediated magnetic interaction and high Tc ferromagnetism in Co doped ZnO nanoparticles.

    Science.gov (United States)

    Pal, Bappaditya; Giri, P K

    2011-10-01

    Structural, optical and magnetic studies have been carried out for the Co-doped ZnO nanoparticles (NPs). ZnO NPs are doped with 3% and 5% Co using ball milling and ferromagnetism (FM) is studied at room temperature and above. A high Curie temperature (Tc) has been observed from the Co doped ZnO NPs. X-ray diffraction and high resolution transmission electron microscopy analysis confirm the absence of metallic Co clusters or any other phase different from würtzite-type ZnO. UV-visible absorption and photoluminescence studies on the doped samples show change in band structure and oxygen vacancy defects, respectively. Micro-Raman studies of doped samples shows defect related additional strong bands at 547 and 574 cm(-1) confirming the presence of oxygen vacancy defects in ZnO lattice. The field dependence of magnetization (M-H curve) measured at room temperature exhibits the clear M-H loop with saturation magnetization and coercive field of the order of 4-6 emu/g and 260 G, respectively. Temperature dependence of magnetization measurement shows sharp ferromagnetic to paramagnetic transition with a high Tc = 791 K for 3% Co doped ZnO NPs. Ferromagnetic ordering is interpreted in terms of overlapping of polarons mediated through oxygen vacancy defects based on the bound magnetic polaron (BMP) model. We show that the observed FM data fits well with the BMP model involving localised carriers and magnetic cations.

  17. Fabrication of Al-Doped ZnO Film with High Conductivity Induced by Photocatalytic Activity

    Science.gov (United States)

    Hong, Jeongsoo; Katsumata, Ken-ichi; Matsushita, Nobuhiro

    2016-10-01

    We have fabricated Al-doped ZnO films by a spin-spray method, achieving high conductivity by Al-ion doping and photocatalytic activity of the ZnO. The surface morphology of the as-deposited films was varied by changing the Al concentration and addition of citrate ions. As-deposited Al-doped ZnO film without citrate ions showed rod array structure with increasing rod width as the Al concentration was increased. Meanwhile, Al-doped ZnO film deposited with addition of citrate ions changed to exhibit dense and continuous surface morphology with high transmittance of 85%. The lowest resistivity recorded for undoped and Al-doped ZnO film was 2.1 × 10-2 Ω cm and 5.9 × 10-3 Ω cm, after ultraviolet (UV) irradiation. The reason for the decreased resistivity is thought to be that Al-ion doping and the photocatalytic activity of ZnO contributed to improve the conductivity.

  18. Magnetic properties of high Li doped ZnO sol–gel thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vettumperumal, R. [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Kalyanaraman, S., E-mail: mayura_priya2003@yahoo.co.in [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Santoshkumar, B. [P.G and Research Department of Physics, Sri Paramakalyani College, Alwarkurichi (India); Thangavel, R. [Department of Physics, Indian School of Mines, Dhanbad (India)

    2014-02-01

    Highlights: • Ferromagnetism in high Li doped ZnO films. • Magnetic properties observed by Guoy's and VSM method. • The rod and wrinkle like structures are observed from the surface of the films. • Band gap of ZnO does not get altered by high Li doping. - Abstract: Undoped and Li doped ZnO thin films were deposited on a glass substrate using the sol–gel dip coating method. The films were prepared at 5 mol.% and 10 mol.% of Li doped ZnO at 550 °C annealing temperature and the deposited films were characterized by X-ray diffraction (XRD), microscopic studies, Gouy's method, vibrating sample magnetometer (VSM) and UV–visible spectroscopy. All the deposited thin films had a hexagonal wurtzite structure with polycrystalline grains at random. Primarily magnetic properties of pure and Li doped ZnO films were observed by Guoy's method which depicted Dia and Para magnetic behavior at room temperature. VSM measurement reveals a coercivity of 97.7 Oe in the films. An inverse relative ferromagnetism was perceived in Li doped ZnO films which had an average transmission of <90%.

  19. Photocatalytic activity of Eu3+-doped ZnO nanorods synthesized via microwave assisted technique

    Institute of Scientific and Technical Information of China (English)

    P.V. Korake; A.N. Kadam; K.M. Garadkar

    2014-01-01

    The doped ZnO nanorods as a photocatalyst with different Eu contents were prepared by microwave assisted method and they were characterized by means of X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), UV-Vis spectroscopy, surface area Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average crystallite size and band gap energy of Eu-doped ZnO were varied with the Eu content. The XRD pattern of Eu-doped ZnO indicated hexagonal crystal structure with an average crystallite size of 25 nm. The pres-ence of europium with trivalent state and its doping successfully into the crystal lattice of ZnO matrix were confirmed by XPS tech-nique. The photocatalytic activity of Eu-doped ZnO nanorods was evaluated for methyl orange degradation. The photocatalytic experi-ments showed~91%degradation of methyl orange over 0.2 mol.%Eu doped ZnO sample within 3 h under UV light (365 nm).

  20. Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: Optical and electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Romeiro, Fernanda C.; Marinho, Juliane Z.; Lemos, Samantha C.S. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Moura, Ana P. de [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Freire, Poliana G. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Silva, Luis F. da; Longo, Elson [LIEC, Instituto de Química, Universidade Estadual Paulista, 14800-900 Araraquara, SP (Brazil); Munoz, Rodrigo A.A. [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil); Lima, Renata C., E-mail: rclima@iqufu.ufu.br [Instituto de Química, Universidade Federal de Uberlândia, 38400-902 Uberlândia, MG (Brazil)

    2015-10-15

    We report for the first time a rapid preparation of Zn{sub 1−2x}Co{sub x}Ni{sub x}O nanoparticles via a versatile and environmentally friendly route, microwave-assisted hydrothermal (MAH) method. The Co, Ni co-doped ZnO nanoparticles present an effect on photoluminescence and electrochemical properties, exhibiting excellent electrocatalytic performance compared to undoped ZnO sample. Photoluminescence spectroscopy measurements indicated the reduction of the green–orange–red visible emission region after adding Co and Ni ions, revealing the formation of alternative pathways for the generated recombination. The presence of these metallic ions into ZnO creates different defects, contributing to a local structural disorder, as revealed by Raman spectra. Electrochemical experiments revealed that the electrocatalytic oxidation of dopamine on ZnO attached to multi-walled carbon nanotubes improved significantly in the Co, Ni co-doped ZnO samples when compared to pure ZnO. - Graphical abstract: Rapid synthesis of Co, Ni co-doped ZnO nanoparticles: optical and electrochemical properties. Co, Ni co-doped ZnO hexagonal nanoparticles with optical and electrocatalytic properties were successfully prepared for the first time using a microwave hydrothermal method at mild conditions. - Highlights: • Co{sup 2+} and Ni{sup 2+} into ZnO lattice obtained a mild and environmentally friendly process. • The heating method strongly influences in the growth and shape of the particles. • Short-range defects generated by the ions insertion affects the photoluminescence. • Doped ZnO nanoparticles improve the electrocatalytic properties of pure oxide.

  1. Study of ZnO and Mg doped ZnO nanoparticles by sol-gel process

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Mohd Meenhaz, E-mail: meenhazphysics@gmail.com; Arshad, Mohd; Tripathi, Pushpendra [Centre of Excellence in Nanomaterials, Department Of Applied Physics Zakir Hussain College of Engineering and Technology, Aligarh Muslim University, Aligarh-202002 (India)

    2015-06-24

    Nano-crystalline undoped and Mg doped ZnO (Mg-ZnO) nanoparticles with compositional formula Mg{sub x}Zn{sub 1-x}O (x=0,1,3,5,7,10 and 12 %) were synthesized using sol-gel process. The XRD diffraction peaks match with the pattern of the standard hexagonal structure of ZnO that reveals the formation of hexagonal wurtzite structure in all samples. SEM images demonstrates clearly the formation of spherical ZnO nanoparticles, and change of the morphology of the nanoparticles with the concentration of the magnesium, which is in close agreement with that estimated by Scherer formula based on the XRD pattern. To investigate the doping effect on optical properties, the UV–VIS absorption spectra was obtained and the band gap of the samples calculated.

  2. Photocatalytic activity of heterostructures based on ZnO and N-doped ZnO.

    Science.gov (United States)

    Qin, Hongchun; Li, Weiying; Xia, Yujing; He, Tao

    2011-08-01

    Different composite films prepared by coupling ZnO and nitrogen-doped ZnO (N-ZnO) were used to photodegrade humic acids (HA). The catalysts exhibit an activity in the order of glass/ZnO/N-ZnO > glass/N-ZnO >glass/ZnO > glass/N-ZnO/ZnO when light is irradiated from the film to glass substrate. However, glass/ZnO/N-ZnO exhibits a lower activity than glass/N-ZnO/ZnO when light is illuminated from glass to film. Moreover, glass/ZnO/N-ZnO shows a lower activity when light is irradiated from glass to film than that irradiated in the opposite direction. These results suggest that it is not always the case that the presence of a heterojunction at interface of two semiconductors can definitely result in improving the photoactivity of the heterostructure although it can suppress the recombination of photogenerated charge carriers. They also indicate that photodegradation of HA is mainly via the oxidization by HO• (rather than directly by O(2)(-) and h(+)), which is produced mainly by the reactions with h(+). This implies the importance of fabrication a right heterojunction at the interface between the composite materials when they are used for photocatalysis. We envision that this work will help to develop new photocatalysts, as well as to understand better the photocatalytic mechanism.

  3. Enhanced Visible Light Photocatalytic Activity of ZnO Nanowires Doped with Mn2+ and Co2+ Ions

    Science.gov (United States)

    Li, Wei; Wang, Guojing; Chen, Chienhua; Liao, Jiecui; Li, Zhengcao

    2017-01-01

    In this research, ZnO nanowires doped with Mn2+ and Co2+ ions were synthesized through a facile and inexpensive hydrothermal approach, in which Mn2+ and Co2+ ions successfully substituted Zn2+ in the ZnO crystal lattice without changing the morphology and crystalline structure of ZnO. The atomic percentages of Mn and Co were 6.29% and 1.68%, respectively, in the doped ZnO nanowires. The photocatalytic results showed that Mn-doped and Co-doped ZnO nanowires both exhibited higher photocatalytic activities than undoped ZnO nanowires. Among the doped ZnO nanowires, Co-doped ZnO, which owns a twice active visible-light photocatalytic performance compared to pure ZnO, is considered a more efficient photocatalyst material. The enhancement of its photocatalytic performance originates from the doped metal ions, which enhance the light absorption ability and inhibit the recombination of photo-generated electron-hole pairs as well. The effect of the doped ion types on the morphology, crystal lattice and other properties of ZnO was also investigated.

  4. Enhanced Visible Light Photocatalytic Activity of ZnO Nanowires Doped with Mn2+ and Co2+ Ions

    Directory of Open Access Journals (Sweden)

    Wei Li

    2017-01-01

    Full Text Available In this research, ZnO nanowires doped with Mn2+ and Co2+ ions were synthesized through a facile and inexpensive hydrothermal approach, in which Mn2+ and Co2+ ions successfully substituted Zn2+ in the ZnO crystal lattice without changing the morphology and crystalline structure of ZnO. The atomic percentages of Mn and Co were 6.29% and 1.68%, respectively, in the doped ZnO nanowires. The photocatalytic results showed that Mn-doped and Co-doped ZnO nanowires both exhibited higher photocatalytic activities than undoped ZnO nanowires. Among the doped ZnO nanowires, Co-doped ZnO, which owns a twice active visible-light photocatalytic performance compared to pure ZnO, is considered a more efficient photocatalyst material. The enhancement of its photocatalytic performance originates from the doped metal ions, which enhance the light absorption ability and inhibit the recombination of photo-generated electron-hole pairs as well. The effect of the doped ion types on the morphology, crystal lattice and other properties of ZnO was also investigated.

  5. The effect of fe-dopant concentration on ethanol gas sensing properties of fe doped ZnO/ZnO shell/core nanorods

    Science.gov (United States)

    Khayatian, A.; Safa, S.; Azimirad, R.; Kashi, M. Almasi; Akhtarianfar, S. F.

    2016-10-01

    In this paper, Fe-doped ZnO/ZnO shell/core nanostructures were synthesized through a simple two-step method and the effects of Fe dopant concentrations (between 0 and 9 at%) on the structural, optical, electrical and gas sensing properties were investigated. The X-ray diffraction analysis revealed that all of the samples are crystallized in the same wurtzite hexagonal crystal structure with (002) peak as the main orientation. Nevertheless, the morphology of shell/core nanorods remained stable with increasing of Fe dopant, but the crystallinity improved. The ultraviolet-visible spectroscopy analysis showed that the Fe ions have coordination number of 3+ in the ZnO shell layer. The participation of Fe3+ ions into ZnO layer was also confirmed by Current-Voltage (I-V) curves where the resistance of nanorods was reduced with Fe concentration. Moreover, the ethanol-sensing properties of the Fe-doped ZnO/ZnO shell/core nanorod sensors were systematically investigated. According to the results, optimum gas sensing was obtained by the addition of 0.5 at% Fe to ZnO shell layer which lead to significant enhancement in ethanol gas response.

  6. Synthesis and Characterization of Molybdenum Doped ZnO Thin Films by SILAR Deposition Method

    Science.gov (United States)

    Radha, R.; Sakthivelu, A.; Pradhabhan, D.

    2016-08-01

    Molybdenum (Mo) doped zinc oxide (ZnO) thin films were deposited on the glass substrate by Successive Ionic Layer Adsorption and Reaction (SILAR) deposition method. The effect of Mo dopant concentration of 5, 6.6 and 10 mol% on the structural, morphological, optical and electrical properties of n-type Mo doped ZnO films was studied. The X-ray diffraction (XRD) results confirmed that the Mo doped ZnO thin films were polycrystalline with wurtzite structure. The field emission scanning electron microscopy (FESEM) studies shows that the surface morphology of the films changes with Mo doping. A blue shift of the optical band gap was observed in the optical studies. Effect of Mo dopant concentration on electrical conductivity was studied and it shows comparatively high electrical conductivity at 10 mol% of Mo doping concentration.

  7. Synthesis of ZnO doped ceria nanoparticles via azeotropic distillation processing

    Institute of Scientific and Technical Information of China (English)

    SONG Xiao-lan; QU Peng; YANG Hua-ming; QIU Guan-zhou

    2006-01-01

    The synthesis of nano-sized ZnO-doped CeO2 of 20 nm in crystal size by a coprecipitation technique was investigated by different scanning calorimetries/thermalgravimetrics(DSC/TG),X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet (UV) absorbance. Azeotropic distillation processing was performed to effectively eliminate the residual water inside the as-prepared precipitate. Doping of ZnO results in the formation of solid solution. The crystal size of the nanoparticles increases with the increase of the doped ZnO amount,the calcination temperature and time. Doped CeO2 nanoparticles show excellent visible-light property and ultraviolet-absorption activity. Doping of ZnO doesn't not weaken the UV-shielding property of ceria.

  8. Growth of arrays of Al-doped ZnO nanocones by pulsed laser deposition.

    Science.gov (United States)

    Sun, Ye; Addison, Katherine E; Ashfold, Michael N R

    2007-12-12

    Arrays of aligned Al-doped ZnO nanocones have been synthesized by pulsed laser deposition following excimer laser ablation of a ceramic ZnO target containing 2% Al(2)O(3) (by weight). The elemental composition, microstructural and optical properties of the products were examined by laser induced breakdown spectroscopy, electron microscopy, x-ray diffraction and room temperature photoluminescence measurements. The incident laser fluence was identified as a key parameter in nanocone formation. Their tapered morphologies and small tip diameters (approximately 5 nm) suggest that Al-doped ZnO nanocones could find application as field emitters and as a gas sensing material.

  9. Photocatalytic studies of crystal violet dye using mn doped and PVP capped ZnO nanoparticles.

    Science.gov (United States)

    Mittal, Manish; Sharma, Manoj; Pandey, O P

    2014-04-01

    Mn (0.5%, 1%, 1.5% and 2%) doped and undoped ZnO nanoparticles (NPs) capped with PVP (1.0%) were successfully synthesized via co-precipitation approach using zinc acetate, sodium hydroxide and manganese acetate as precursors. Structural analysis was performed by XRD confirming phase purity and crystalline wurtzite structure. TEM results show average particle size 15-20 nm and 22-25 nm for Mn (1%) and Mn (2%) doped ZnO NPs respectively. Manganese (Mn) doping has led to reduction in band gap which facilitate the absorption of radiation in visible region. The Photocatalytic activity of undoped and Mn (0.5%,1%,1.5% and 2%) doped NPs was analyzed via degradation of crystal violet (CV) dye. The crystal violet decomposition rate of undoped and Mn doped NPs were studied under UV-visible region. It is observed from degradation studies that the doping has a pronounced effect on the photocatalytic activity of ZnO NPs. Kinetic studies shows that photo degradation of CV follow a pseudo first-order kinetic law. Experiments for reusability of Mn (1%) doped with PVP (1%) capped ZnO were also performed to determine the stability of as prepared sample. It shows an increase in catalytic activity of NPs by small amount when exposed to UV irradiation for 3 h. Photoluminescence and UV-Visible absorption spectroscopy studies were also performed for studying the effect of UV irradiation on the surface of ZnO NPs.

  10. Influence of laser doping on nanocrystalline ZnO thin films gas sensors

    Directory of Open Access Journals (Sweden)

    Yue Hou

    2017-08-01

    Full Text Available The effect of laser doping of Al on the gas sensing behavior of nanocrystalline ZnO thin films is reported. The doping of Al was carried out by the spin-coating of Al-precursors on nanocrystalline ZnO films followed by a pulsed laser irradiation. The laser-doped films were characterized as a function of laser power density by measuring the optical, structural, electrical, morphological and gas sensing properties of ZnO films. It was found that the laser doping process resulted in an increase of electrical conductivity of ZnO films. The performance of gas sensor was investigated for different concentrations of H2 and NH3 in the air. The results indicate that the laser doping process can be utilized to improve the sensor characteristics such as sensitivity and response time by optimization of laser power density. The optimum laser power is interpreted as the critical power level required to compete the effective doping versus developing the effective grain boundaries. Also, the selectivity of laser-doped ZnO sensors for H2 was studied for a likelihood practical gas mixture composed of H2, NH3 and CH4. It is found that these films can be optimized to develop H2 and NH3 sensors in PPM level with a higher selectivity over other reducing gases.

  11. Ag-doped ZnO nanorods synthesized by two-step method

    Institute of Scientific and Technical Information of China (English)

    Chen Xian-Mei; Ji Yong; Gao Xiao-Yong; Zhao Xian-Wei

    2012-01-01

    A two-step method is adopted to synthesize Ag-doped ZnO nanorods.A ZnO seed layer is first prepared on a glass substrate by thermal decomposition of zinc acetate.Ag-doped ZnO nanorods are then assembled on the ZnO seed layer using the hydrothermal method.The influences of the molar percentage of Ag ions to Zn ions (RAg/Zn) on the structural and optical properties of the ZnO nanorods obtained are carefully studied using X-ray diffractometry,scanning electron microscopy and spectrophotometry.Results indicate that Ag ions enter into the crystal lattice through the substitution of Zn ions.The 〈002〉 c-axis-preferred orientation of the ZnO nanorods decreases as RAg/Zn increases.At RAg/Zn > 1.0%,ZnO nanorods lose their c-axis-preferred orientation and generate Ag precipitates from the ZnO crystal lattice.The average transmissivity in the visible region first increases and then decreases as RAg/Zn increases.The absorption edge is first blue shifted and then red shifted.The influence of Ag doping on the average head face,and axial dimensions of the ZnO nanorods may be optimized to improve the average transmissivity at RAg/Zn < 1.0%.

  12. Enhanced the photocatalytic activity of Ni-doped ZnO thin films: Morphological, optical and XPS analysis

    Science.gov (United States)

    Abdel-wahab, M. Sh.; Jilani, Asim; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-06-01

    Pure and Ni-doped ZnO thin films with different concentration of Ni (3.5 wt%, 5 wt%, 7 wt%) were prepared by DC/RF magnetron sputtering technique. The X-rays diffraction pattern showed the polycrystalline nature of pure and Ni-doped ZnO thin films. The surface morphology of pure and Ni doped ZnO thin films were investigated through atomic force microscope, which indicated the increase in the grain dimension and surface roughness with increasing the Ni doping. The UV-Visible transmission spectra showed the decrease in the transmittance of doped ZnO thin films with the incorporation of Ni dopants. The surface and chemical state analysis of pure and Ni doped ZnO thin films were investigated by X-rays photoelectron spectroscopy (XPS). The photocatalytic activities were evaluated by an aqueous solution of methyl green dye. The tungsten lamp of 500 W was used as a source of visible light for photocatalytic study. The degradation results showed that the Ni-doped ZnO thin films exhibit highly enhanced photocatalytic activity as compared to the pure ZnO thin films. The enhanced photocatalytic activities of Ni-doped ZnO thin films were attributed to the enhanced surface area (surface defects), surface roughness and decreasing the band gap of Ni-doped ZnO thin films. Our work supports the applications of thin film metal oxides in waste water treatment.

  13. (Al, Er) co-doped ZnO nanoparticles for photodegradation of rhodamine blue

    Science.gov (United States)

    Ghomri, R.; Shaikh, M. Nasiruzzaman; Ahmed, M. I.; Bououdina, M.; Ghers, M.

    2016-10-01

    Pure and co-doped (Al, Er) ZnO nanoparticles (NPs) have been synthesized by hydrothermal method using (Zn, Er and Al) nitrates. X-ray diffraction patterns reveal the formation of single phase of ZnO würtzite-type structure. The crystallite size for pure ZnO is in the order of 26.5 nm which decreases up to the range 14.2-22.0 nm after (Al, Er) co-doping. SEM micrographs show that the specimen is composed of regular spherical particles in the nanoscale regime with homogeneous size distribution and high tendency to agglomeration. FTIR spectra exhibit absorption lines located at wavenumbers corresponding to vibration modes between the constituent atoms. Raman spectra recorded under excitation ( λ exc = 632.8 nm) reveal peaks related to modes of transverse and longitudinal optical phonons of the würtzite ZnO structure. The energy band gap E g of ZnO:(Al, Er) NPs ranges in 3.264-3.251 eV. The photocatalytic activity of pure and co-doped (Al, Er) ZnO NPs was evaluated by the photodegradation of rhodamine blue under an irradiation of wavelength 554 nm. It is found that a photodegradation rate above 90 % could be achieved for a period of time of 40 min for pure ZnO and 120 min for (Al, Er) co-doped ZnO. A photodegradation mechanism is proposed.

  14. Nd-doped ZnO monolayer: High Curie temperature and large magnetic moment

    Science.gov (United States)

    Tan, Changlong; Sun, Dan; Zhou, Long; Tian, Xiaohua; Huang, Yuewu

    2016-10-01

    We performed first-principles calculations within density-functional theory to study the structural, electronic, and magnetic properties of Nd-doped ZnO monolayer. The calculated results reveal that Nd-doped ZnO monolayer exhibits stable room temperature ferromagnetism with a large saturation magnetic moment of 3.99 μB per unit in ZnO monolayer. The magnetic property is contributed to the localized f sates of Nd atoms. When two Zn atoms are substituted by two Nd dopants, they tend to form ferromagnetic (FM) coupling and the estimated Curie temperature is higher than room temperature. More interesting, the impurity bands appear within the band gap of ZnO monolayer due to the introduction of Nd dopant. Our results may provide a reference for modifying the material property of ZnO monolayer and are promising as nanoscale building block in spintronic devices.

  15. Transport and structural characterization of solution-processable doped ZnO nanowires

    KAUST Repository

    Noriega, Rodrigo

    2009-08-18

    The use of ZnO nanowires has become a widespread topic of interest in optoelectronics. In order to correctly assess the quality, functionality, and possible applications of such nanostructures it is important to accurately understand their electrical and optical properties. Aluminum- and gallium-doped crystalline ZnO nanowires were synthesized using a low-temperature solution-based process, achieving dopant densities of the order of 1020 cm-3. A non-contact optical technique, photothermal deflection spectroscopy, is used to characterize ensembles of ZnO nanowires. By modeling the free charge carrier absorption as a Drude metal, we are able to calculate the free carrier density and mobility. Determining the location of the dopant atoms in the ZnO lattice is important to determine the doping mechanisms of the ZnO nanowires. Solid-state NMR is used to distinguish between coordination environments of the dopant atoms.

  16. Magnetic study of 0.20(Fe{sub 2}O{sub 3})/0.80(ZnO) nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Typek, J., E-mail: typjan@zut.edu.pl [Institute of Physics, West Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin (Poland); Wardal, K.; Zolnierkiewicz, G. [Institute of Physics, West Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin (Poland); Guskos, N. [Institute of Physics, West Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin (Poland); Solid State Physics, Department of Physics, University of Athens, Panepistimiopolis, 15 784 Zografos, Athens (Greece); Sibera, D.; Narkiewicz, U. [Institute of Chemical and Environment Engineering, West Pomeranian University of Technology, K. Pulaskiego 10, 70-322 Szczecin (Poland)

    2014-06-01

    ZnO nanocrystals doped with Fe{sub 2}O{sub 3} have been synthesized by the calcination method. Ferromagnetic resonance (FMR) and dc magnetization measurements of 0.2(Fe{sub 2}O{sub 3})/0.8(ZnO) nanocomposite have been carried out in the 4–300 K range. The presence of agglomerated magnetic zinc ferrite ZnFe{sub 2}O{sub 4} nanoparticles in 0.2(Fe{sub 2}O{sub 3})/0.8(ZnO) nanocomposite with an average crystallite size of 8 nm was identified by XRD. Temperature dependence of the resonance field, linewidth and the integrated intensity calculated from FMR spectra has been determined. Magnetization measurements in ZFC and FC modes as well as study of hysteresis loops allowed calculating different magnetic characteristics – blocking/freezing temperature, magnetic moment, anisotropy constant and anisotropy field. The observed magnetic properties of 0.2(Fe{sub 2}O{sub 3})/0.8(ZnO) nanocomposite were explained based on the core–shell model of ZnFe{sub 2}O{sub 4} nanoparticles covered by ZnO layer. - Highlights: • ZnFe{sub 2}O{sub 4} nanoparticles in ZnO matrix have been synthesized. • Magnetization and FMR studies in 4–300 K range have been carried out. • Magnetic characteristics of ZnFe{sub 2}O{sub 4} were calculated in terms of core–shell model. • Magnetic phases of ZnFe{sub 2}O{sub 4} nanoparticles have been determined.

  17. Oriented grain growth in ZnO thin films by Iodine doping

    Science.gov (United States)

    Thomas, Deepu; Vattappalam, Sunil C.; Mathew, Sunny; Augustine, Simon

    2015-02-01

    ZnO thin films were prepared by Successive Ionic Layer Adsorption Reaction (SILAR) method. Oriented grain growth in Iodine doped ZnO thin films were studied. The oriented grain growth in samples was studied by comparing the peak intensities from X-ray diffraction data and surface morphology by scanning electron microscopy. It is found that oriented grain growth significantly enhanced by Iodine doping. When the oriented grain growth increases, crystallinity of the thin film improves, resistance and band gap decrease. ZnO thin films having good crystallinity with preferential (002) orientation is a prerequisite for the fabrication of devices like UV diode lasers, acoustic- optic devices etc. A possible mechanism for the oriented grain growth is also investigated. It is inferred that creation of point defects is responsible for the enhanced oriented grain growth in ZnO thin films when doped with iodine.

  18. A vanadium-doped ZnO nanosheets-polymer composite for flexible piezoelectric nanogenerators.

    Science.gov (United States)

    Shin, Sung-Ho; Kwon, Yang Hyeog; Lee, Min Hyung; Jung, Joo-Yun; Seol, Jae Hun; Nah, Junghyo

    2016-01-21

    We report high performance flexible piezoelectric nanogenerators (PENGs) by employing vanadium (V)-doped ZnO nanosheets (NSs) and the polydimethylsiloxane (PDMS) composite structure. The V-doped ZnO NSs were synthesized to overcome the inherently low piezoelectric properties of intrinsic ZnO. Ferroelectric phase transition induced in the V-doped ZnO NSs contributed to significantly improve the performance of the PENGs after the poling process. Consequently, the PENGs exhibited high output voltage and current up to ∼32 V and ∼6.2 μA, respectively, under the applied strain, which are sufficient to directly turn on a number of light emitting diodes (LEDs). The composite approach for PENG fabrication is scalable, robust, and reproducible during periodic bending/releasing over extended cycles. The approach introduced here extends the performance limits of ZnO-based PENGs and demonstrates their potential as energy harvesting devices.

  19. Fabrication and Magnetic Properties of Sn-Doped ZnO Microstructures via Hydrothermal Method.

    Science.gov (United States)

    Farooq, M Hassan; Hussain, Riaz; Iqbal, M Zubair; Shah, M W; Rana, Usman Ali; Khan, Salah Ud-Din

    2016-01-01

    Pure zinc oxide (ZnO) and Sn-doped ZnO hexagonal sheets were synthesized by template free hydrothermal growth mechanism with controlled morphology by using zinc acetate dihydrate (Zn(CH₃COO)₂· 2H₂O), tin chloride pentahydrate (SnCl₄ · 5H₂O), Polyvinylpyrrolidone (PVP) and H₂O as precursors. The structural, physical, chemical, and magnetic characteristics were investigated by X-ray diffraction, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy and alternating gradient magnetometer (AGM), respectively. The average crystalline size of hexagonal phase of ZnO sheets was calculated to be about 34 nm from XRD patterns. Energy dispersive spectroscopy provided the compositional analysis of pure and Sn-doped ZnO. Room temperature ferromagnetism (RTFM) was observed by AGM for pure and Sn-doped ZnO hexagonal plates. RTFM increases monotonically for Sn doping and reaches maximum saturation magnetization 0.045 emu/g for 3% Sn-doped ZnO.

  20. Modulation-Doped In2O3/ZnO Heterojunction Transistors Processed from Solution

    KAUST Repository

    Khim, Dongyoon

    2017-03-15

    This paper reports the controlled growth of atomically sharp In2 O3 /ZnO and In2 O3 /Li-doped ZnO (In2 O3 /Li-ZnO) heterojunctions via spin-coating at 200 °C and assesses their application in n-channel thin-film transistors (TFTs). It is shown that addition of Li in ZnO leads to n-type doping and allows for the accurate tuning of its Fermi energy. In the case of In2 O3 /ZnO heterojunctions, presence of the n-doped ZnO layer results in an increased amount of electrons being transferred from its conduction band minimum to that of In2 O3 over the interface, in a process similar to modulation doping. Electrical characterization reveals the profound impact of the presence of the n-doped ZnO layer on the charge transport properties of the isotype In2 O3 /Li-ZnO heterojunctions as well as on the operating characteristics of the resulting TFTs. By judicious optimization of the In2 O3 /Li-ZnO interface microstructure, and Li concentration, significant enhancement in both the electron mobility and TFT bias stability is demonstrated.

  1. Electrodeposition of Al-doped ZnO nanoflowers with enhanced photocatalytic performance.

    Science.gov (United States)

    She, Guangwei; Chen, Xue; Wang, Yao; Qi, Xiaopeng; Mu, Lixuan; Shi, Wensheng

    2012-03-01

    In this study, Al-doped ZnO nanoflowers were fabricated on conductive substrates via a simple electrodeposition process. The Al-doped ZnO nanoflowers are three-dimensional micro/nano hierarchical structures composed of numerous nanosheets. The chemical composition and crystal structure of the as-synthesized nanoflowers were characterized by EDS, XPS, XRD and HRTEM. It was found that the Al doping led to the decrease of the band gap of ZnO from 3.21 eV to 3.07 eV. Considering the large surface areas, the Al-doped ZnO nanoflowers were used as the photocatalyst for degradation of methyl orange, and exhibited a significantly enhanced performance comparing with the undoped ZnO nanostructures. The good photocatalytic performance should be related to the large surface areas of the nanoflowers and the more free carriers in the Al-doped ZnO, which are introduced by the dopants.

  2. Raman Submicron Spatial Mapping of Individual Mn-doped ZnO Nanorods.

    Science.gov (United States)

    Strelchuk, V; Kolomys, O; Rarata, S; Lytvyn, P; Khyzhun, O; Chey, Chan Oeurn; Nur, Omer; Willander, Magnus

    2017-12-01

    ZnO nanorods (NRs) arrays doped with a large concentration of Mn synthesized by aqueous chemical growth and were characterized by SEM, photoluminescence, Raman scattering, magnetic force microscopy (MFM). By comparison of spectra taken on pure and Mn-doped ZnO NRs, a few new Raman impurity-related phonon modes, resulting from the presence of Mn in the investigated samples. We also present a vibrational and magnetic characterization of individual lying nanorods using Raman and MFM imaging. Confocal scanning micro-Raman mapping of the spatial distribution of intensity and frequency of phonon modes in single Mn-doped ZnO NRs nanorods is presented and analyzed for the first time. Mn-related local vibrational modes are also registered in Raman spectra of the single nanorod, confirming the incorporation of Mn into the ZnO host matrix. At higher Mn concentration the structural transformation toward the spinel phase ZnMn2O4 and Mn3O4 is observed mainly in 2D bottom layers. MFM images of Mn-doped ZnO NR arrays and single nanorod were studied in nanoscale at room temperature and demonstrate magnetic behavior. The circular domain magnetic pattern on top of single nanorod originated to superposition of some separate domains inside rod. This demonstrates that long-range ferromagnetic order is present at room temperature. Aligned Mn-doped ZnO NRs demonstrates that long-range ferromagnetic order and may be applied to future spintronic applications.

  3. Damage annealing in low temperature Fe/Mn implanted ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Gunnlaugsson, H. P. [University of Aarhus, Department of Physics and Astronomy (Denmark); Bharuth-Ram, K., E-mail: kbr@tlabs.ac.za [Durban University of Technology, Physics Department (South Africa); Johnston, K. [PH Department, ISOLDE/CERN (Switzerland); Langouche, G. [University of Leuven, Instituut voor Kern-en Stralings fysika (Belgium); Mantovan, R. [Laboratorio MDM, IMM-CNR (Italy); Mølholt, T. E. [University of Iceland, Science Institute (Iceland); Naidoo, D. [University of the Witwatersrand, School of Physics (South Africa); Ólafsson, O. [University of Iceland, Science Institute (Iceland); Weyer, G. [University of Aarhus, Department of Physics and Astronomy (Denmark)

    2015-04-15

    {sup 57}Fe Emission Mössbauer spectra obtained after low fluence (<10{sup 12} cm {sup −2}) implantation of {sup 57}Mn (T{sub 1/2}= 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe {sup 2+} and Fe {sup 3+} on Zn sites, interstitial Fe and Fe in damage regions (Fe {sub D}). The Fe {sub D} component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (∼10{sup 15} cm {sup −2}){sup 57}Fe/ {sup 57}Co implanted ZnO and {sup 57}Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT.

  4. Enhanced photocatalytic activity of Co doped ZnO nanodisks and nanorods prepared by a facile wet chemical method.

    Science.gov (United States)

    Kuriakose, Sini; Satpati, Biswarup; Mohapatra, Satyabrata

    2014-07-07

    Cobalt doped ZnO nanodisks and nanorods were synthesized by a facile wet chemical method and well characterized by X-ray diffraction, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy, photoluminescence spectroscopy, Raman spectroscopy and UV-visible absorption spectroscopy. The photocatalytic activities were evaluated for sunlight driven degradation of an aqueous methylene blue (MB) solution. The results showed that Co doped ZnO nanodisks and nanorods exhibit highly enhanced photocatalytic activity, as compared to pure ZnO nanodisks and nanorods. The enhanced photocatalytic activities of Co doped ZnO nanostructures were attributed to the combined effects of enhanced surface area of ZnO nanodisks and improved charge separation efficiency due to optimal Co doping which inhibit recombination of photogenerated charge carriers. The possible mechanism for the enhanced photocatalytic activity of Co doped ZnO nanostructures is tentatively proposed.

  5. Improved photovoltaic performance of multiple carbon-doped ZnO nanostructures under UV and visible light irradiation.

    Science.gov (United States)

    Liu, Xianbin; Du, Hejun; Sun, Xiao Wei; Zhan, Zhaoyao; Sun, Gengzhi; Li, Fengji; Zheng, Lianxi; Zhang, Sam

    2014-09-01

    We report synthesis of multiple carbon-doped ZnO nanostructures by using carbon cloth as substrates to obtain multiple hollow ZnO microtube-nanowire structures. X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy analysis clearly show that carbon is doped into ZnO through substitution of carbon for oxygen in the growth and annealing processes. Upon exposure to 633-nm red laser, a distinct photoresponse can be observed, which indicates that carbon doping in ZnO can well extend its light harvesting to visible light region. Furthermore, a prototype of photovoltaic cell was fabricated to demonstrate the photovoltaic performance of multiple carbon-doped ZnO nanostructures under UV and visible light irradiation. This result shows that carbon-doped ZnO can act as effective photoactive materials for photoelectric components.

  6. Magnetic, optical and structural property studies of Mn-doped ZnO nanosheets.

    Science.gov (United States)

    Ahmed, Faheem; Kumar, Shalendra; Arshi, Nishat; Anwar, M S; Kim, Geun Woo; Heo, Si Nae; Byon, Eung Sun; Lee, Sung Hun; Lyu, Nam Jin; Koo, Bon Heun

    2012-07-01

    We report the synthesis of pure and Mn doped ZnO in the form of nanosheets using a simple and single step procedure involving a microwave assisted chemical method. As prepared Mn-doped ZnO nanosheets were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible (UV-Vis), Raman spectroscopy and magnetization measurements. The structural studies using XRD and TEM revealed the absence of Mn-related secondary phases and showed that Mn-doped ZnO comprise a single phase nature with wurtzite structure. FESEM and TEM micrographs show that the average diameter of Mn-ZnO assembled nanosheets is about approximately 50 nm, and the length of a Mn-doped ZnO nanosheet building block which is made up of thin mutilayered sheets is around approximately 300 nm. Concerning the Raman scattering spectra, the shift in peak position of E2 (high) mode toward low frequencies due to the Mn doping could be explained well by means of the spatial correlation model. Magnetic measurements showed that Mn-doped ZnO nanosheets exhibit ferromagnetic ordering at or above room temperature.

  7. Ag-doped ZnO nanoellipsoids: potential scaffold for photocatalytic and sensing applications.

    Science.gov (United States)

    Kumar, Ramesh; Rana, Dilbag; Umar, Ahmad; Sharma, Pankaj; Chauhan, Suvarcha; Chauhan, Mohinder Singh

    2015-05-01

    Well-crystalline Ag-doped ZnO nanoellipsoids (NEs) were synthesized in large quantity and used as effective photocatalyst for the photocatalytic degradation of methyl orange (MO) and efficient electron mediator for the fabrication of highly sensitive, reliable and robust hydrazine chemical sensor. The Ag-doped NEs were synthesized by facile low-temperature (~60°C) solution process and characterized in detail using various characterization techniques. The characterizations revealed that the synthesized nanostructures are well-crystalline, possessing ellipsoidal shapes and were grown in very high density. The photocatalytic activities of these Ag-doped NEs were evaluated by measuring the rate of photodegradation reaction of hazardous methyl orange (MO) dye under UV light irradiation. By comparing the photocatalytic performance of Ag-doped ZnO NEs with those of ZnO nanoflowers, the former was found to be a much superior photocatalyst than the later. Further, Ag-doped ZnO NEs based hydrazine sensor exhibited a high sensitivity of ~9.46 µA/cm(2)µM and detection limit of 0.07 µM in a response time of doped ZnO nanomaterials synthesized by simple solution process holds potential as efficient photocatalysts and efficient electron mediators for the fabrication of robust and highly sensitive chemical sensors.

  8. Solution-based synthesis of cobalt-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Vempati, Sesha [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Shetty, Amitha [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India); Dawson, P., E-mail: p.dawson@qub.ac.uk [School of Mathematics and Physics, Queen' s University Belfast, BT7 1NN (United Kingdom); Nanda, K.K.; Krupanidhi, S.B. [Materials Research Center, Indian Institute of Science, Bangalore 560012 (India)

    2012-12-01

    Undoped and cobalt-doped (1-4 wt.%) ZnO polycrystalline, thin films have been fabricated on quartz substrates using sequential spin-casting and annealing of simple salt solutions. X-ray diffraction (XRD) reveals a wurzite ZnO crystalline structure with high-resolution transmission electron microscopy showing lattice planes of separation 0.26 nm, characteristic of (002) planes. The Co appears to be tetrahedrally co-ordinated in the lattice on the Zn sites (XRD) and has a charge of + 2 in a high-spin electronic state (X-ray photoelectron spectroscopy). Co-doping does not alter the wurzite structure and there is no evidence of the precipitation of cobalt oxide phases within the limits of detection of Raman and XRD analysis. Lattice defects and chemisorbed oxygen are probed using photoluminescence and Raman spectroscopy - crucially, however, this transparent semiconductor material retains a bandgap in the ultraviolet (3.30-3.48 eV) and high transparency (throughout the visible spectral regime) across the doping range. - Highlights: Black-Right-Pointing-Pointer Simple solution-based method for the fabrication of Co-doped ZnO thin films. Black-Right-Pointing-Pointer Evidence for Co substitution on Zn sites in + 2 oxidation state. Black-Right-Pointing-Pointer ZnO, with up to 4% Co doping, retains high transparency across visible spectrum. Black-Right-Pointing-Pointer Quenching of exciton photoluminescence linked to chemisorbed oxygen in Co-doped ZnO.

  9. Defect Chemistry Study of Nitrogen Doped ZnO Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Miami University: Dr. Lei L. Kerr (PI, PD) Wright State University: Dr. David C. Look (PI) and Dr. Zhaoqiang Fang (Co-PI)

    2009-11-29

    Our team has investigated the defect chemistry of ZnO:N and developed a thermal evaporation (vapor-phase) method to synthesis p-type ZnO:N. Enhanced p-type conductivity of nitrogen doped ZnO via nano/micro structured rods and Zn-rich Co-doping process were studied. Also, an extended X-Ray absorption fine structure study of p-type nitrogen doped ZnO was conducted. Also reported are Hall-effect, photoluminescence, and DLTS studies.

  10. Preparation of Al-doped ZnO nanocrystalline aggregates with enhanced performance for dye adsorption

    Science.gov (United States)

    Zhang, Jin; Que, WenXiu; Yuan, Yuan; Zhong, Peng; Liao, YuLong

    2012-07-01

    Al-doped ZnO (AZO) nanocrystalline aggregates (NCAs) were prepared by a low cost colloid chemistry method and effects of the Al-doped concentration on the morphological and structural properties of the AZO NCAs were studied. The dye adsorption ability of the AZO NCAs with various Al-doped concentrations was also investigated. Results indicate that the doping of the Al ions not only does not change the wurtzite structure of the ZnO crystal but also can reduce the crystallite grain size and the particle size distribution of the NCAs, which gives them a higher specific surface area and dye adsorption ability than that of the ZnO NCAs. The as-prepared AZO NCAs would be a promising material to be applied in the dye sensitized solar cells and water treatment.

  11. One-Step Synthesis of Monodisperse In-Doped ZnO Nanocrystals

    Directory of Open Access Journals (Sweden)

    Wang QingLing

    2010-01-01

    Full Text Available Abstract A method for the synthesis of high quality indium-doped zinc oxide (In-doped ZnO nanocrystals was developed using a one-step ester elimination reaction based on alcoholysis of metal carboxylate salts. The resulting nearly monodisperse nanocrystals are well-crystallized with typically crystal structure identical to that of wurtzite type of ZnO. Structural, optical, and elemental analyses on the products indicate the incorporation of indium into the host ZnO lattices. The individual nanocrystals with cubic structures were observed in the 5% In–ZnO reaction, due to the relatively high reactivity of indium precursors. Our study would provide further insights for the growth of doped oxide nanocrystals, and deepen the understanding of doping process in colloidal nanocrystal syntheses.

  12. Preparation and Characterization of Sn-doped ZnO Particles with Low Infrared Emissivity

    Institute of Scientific and Technical Information of China (English)

    赵亮; 朱永平

    2012-01-01

    Sn-doped ZnO particles were successfully synthesized by chemical co-precipitation method.Their morphology,phase,microstructure and infrared emissivity were characterized.The results show that the Sn-doped ZnO particles are of ellipsoid shape,their crystalline structure changed with thermal process temperature,the optimal thermal process temperature and Sn-doped proportion are 1000 ℃ and 15%,respectively,the minimum emissivity values are 0.42,0.28,0.46 and 0.48 corresponding to the infrared wavelengths of 0~∞,3~5,8~14 and 14~20 μm,which indicates that the Sn-doped ZnO particles have the application potential as low infrared emissivity material.

  13. Growth and optical properties of ZnO nanorod arrays on Al-doped ZnO transparent conductive film

    OpenAIRE

    Lin, Suanzhi; Hu, Hailong; Zheng, Weifeng; Qu, Yan; Lai, Fachun

    2013-01-01

    ZnO nanorod arrays (NRAs) on transparent conductive oxide (TCO) films have been grown by a solution-free, catalyst-free, vapor-phase synthesis method at 600°C. TCO films, Al-doped ZnO films, were deposited on quartz substrates by magnetron sputtering. In order to study the effect of the growth duration on the morphological and optical properties of NRAs, the growth duration was changed from 3 to 12 min. The results show that the electrical performance of the TCO films does not degrade after t...

  14. Multi-walled carbon nanotube-supported metal-doped ZnO nanoparticles and their photocatalytic property.

    Science.gov (United States)

    Chen, C S; Liu, T G; Lin, L W; Xie, X D; Chen, X H; Liu, Q C; Liang, B; Yu, W W; Qiu, C Y

    2013-01-01

    A simple and versatile approach has been developed to synthesize multi-walled carbon nanotubes/metal-doped ZnO nanohybrid materials (MWNT/M-doped ZnO) by means of the co-deposition method. The experimental results illuminate that MWNTs can be modified by metal-doped ZnO nanoparticles at 450 °C, such as Mn, Mg, and Co elements. Furthermore, the MWNT/Mg-doped ZnO hybrids have been proven to have a high photocatalytic ability for methyl orange (MO), in which the degraded rate for MO reaches 100 % in 60 min. The enhancement in photocatalytic activity is attributed to the excellent electriconal property of MWNTs and Mg-doping. The resultant MWNT/Mg-doped ZnO nanohybrids have potential applications in photocatalysis and environmental protection.

  15. Growth and characterization of Cl-doped ZnO hexagonal nanodisks

    Science.gov (United States)

    Yousefi, Ramin; Zak, A. K.; Mahmoudian, M. R.

    2011-10-01

    Cl-doped ZnO nanodisks were grown on a Si(111) substrate using a thermal evaporation method. The prepared nanodisks exhibited a hexagonal shape with an average thickness of 50 nm and average diagonal of 270 nm. In addition, undoped ZnO disks with hexagonal shape were grown under the same conditions, but the sizes of these undoped ZnO disks were on the micrometer order. A possible mechanism was proposed for the growth of the Cl-doped ZnO nanodisks, and it was shown that the Cl 1- anions play a crucial role in controlling the size. X-ray diffraction and Raman spectroscopy clearly showed an extension in the crystal lattice of ZnO because of the presence of chlorine. In addition, these nanodisks produced a strong photoluminescence emission peak in the ultraviolet (UV) region and a weak peak in the green region of the electromagnetic spectrum. Furthermore, the UV peak of the Cl-doped ZnO nanodisks was blueshifted with respect to that of the undoped ZnO disks.

  16. Ge doping of FeGa3

    Science.gov (United States)

    Alvarez-Quiceno, J. C.; Cabrera-Baez, M.; Munévar, J.; Micklitz, H.; Bittar, E. M.; Baggio-Saitovitch, E.; Ribeiro, R. A.; Avila, M. A.; Dalpian, G. M.; Osorio-Guillén, J. M.

    2015-03-01

    The intermetallic narrow-gap semiconductor FeGa3 is one of the few Fe-based diamagnetic materials. Experimentally, Ge doping induces a ferromagnetic (FM) state. The mechanism responsible for this FM response is still unestablished, but there are proposals of itinerant magnetism to explain this behavior. Our DFT simulations show that inserting holes induces a delocalized FM response, while inserting electrons induces a localized FM response around some Fe atoms. We also modeled different distributions of Ge substitution and observe that the FM response depends on the Ge concentration and also on the Ge distribution on the Ga sites. We observed that the extra electrons become localized in some specific Fe atoms, rather than delocalized over the entire crystal lattice, as expected from an itinerant model. For experimental probing of this scenario, we have performed 57Fe Mössbauer spectroscopy on flux-grown singlecrystalline samples. The resulting resonance peak shape supports a localized model for ferromagnetism, since it is possible to resolve the presence of two distinct Fe isomer shifts (despite a single crystallographic site), expected to correspond to Fe atoms with high and low magnetic moments. The authors thank Capes, CNPQ and FAPESP for financial support.

  17. Luminescence Properties of Sm3+/Eu3+ Co-Doped ZnO Quantum Dots.

    Science.gov (United States)

    Liu, Fengyi; Li, Hong; Hu, Yajing; Na, Jin; Mou, Yun; Yang, Kun; Ye, Zuhu; Li, Mingyue; Xie, Ya-Hong

    2016-04-01

    In order to improve luminescence properties of semiconductor ZnO quantum dots (QDs), Sm3+/Eu3+ co-doped ZnO QDs have been controllably synthesized by sol-gel method in this paper. ZnO QDs have a spherical shape with mean diameter at about 5-6 nm, which was characterized by high-resolution transmission electron microscopy (HRTEM). ZnO QDs have hexagonal wurtzite structure with parts of Sm3+ and Eu3+ incorporated into the lattice, which was demonstrated by X-ray Diffraction (XRD). Luminescence properties at room temperature (RT) of different amount of Sm3+ and 2 mol% Eu3+ doped ZnO QDs were examined in-depth by optical spectra. In contrast to the Pr3+/Eu3+ co-doped fluorescent performance researched in our previous study, the photoluminescence (PL) spectra indicates the unique luminescence properties of Sm3+/Eu3+ co-doped ZnO QDs. In addition, fluorescence lifetimes were obtained to illustrate the luminous mechanism.

  18. Cu-doped ZnO nanoparticles: Synthesis, structural and electrical properties

    Science.gov (United States)

    Singhal, Sonal; Kaur, Japinder; Namgyal, Tsering; Sharma, Rimi

    2012-04-01

    Pure and Cu doped ZnO nanopowders (5, 10, 15, 20, 25 and 30 at% Cu) have been synthesized using co-precipitation method. Transmission Electron Microscopic analysis has shown the morphology of ZnO nanopowders to be quasi-spherical. Powder X-ray Diffraction studies have revealed the systematic doping of Cu into the ZnO lattice up to 10% Cu, though the peaks corresponding to CuO in 10% Cu are negligibly very small. Beyond this level, there was segregation of a secondary phase corresponding to the formation of CuO. Fourier Transform Infrared spectra have shown a broad absorption band at ∼490 cm-1 for all the samples, which corresponds to the stretching vibration of Zn-O bond. DC electrical resistivity has been found to decrease with increasing Cu content. The activation energy has also been observed to decrease with copper doping i.e. from ∼0.67 eV for pure ZnO to ∼0.41 eV for 30 at% Cu doped ZnO.

  19. Cu-doped ZnO nanoparticles: Synthesis, structural and electrical properties

    Energy Technology Data Exchange (ETDEWEB)

    Singhal, Sonal, E-mail: sonal1174@gmail.com [Department of Chemistry, Panjab University, Chandigarh 160014 (India); Kaur, Japinder; Namgyal, Tsering; Sharma, Rimi [Department of Chemistry, Panjab University, Chandigarh 160014 (India)

    2012-04-15

    Pure and Cu doped ZnO nanopowders (5, 10, 15, 20, 25 and 30 at% Cu) have been synthesized using co-precipitation method. Transmission Electron Microscopic analysis has shown the morphology of ZnO nanopowders to be quasi-spherical. Powder X-ray Diffraction studies have revealed the systematic doping of Cu into the ZnO lattice up to 10% Cu, though the peaks corresponding to CuO in 10% Cu are negligibly very small. Beyond this level, there was segregation of a secondary phase corresponding to the formation of CuO. Fourier Transform Infrared spectra have shown a broad absorption band at {approx}490 cm{sup -1} for all the samples, which corresponds to the stretching vibration of Zn-O bond. DC electrical resistivity has been found to decrease with increasing Cu content. The activation energy has also been observed to decrease with copper doping i.e. from {approx}0.67 eV for pure ZnO to {approx}0.41 eV for 30 at% Cu doped ZnO.

  20. Tunable Band Gap Energy of Mn-Doped ZnO Nanoparticles Using the Coprecipitation Technique

    Directory of Open Access Journals (Sweden)

    Tong Ling Tan

    2014-01-01

    Full Text Available A simple coprecipitation technique was introduced to form manganese (Mn doped on zinc oxide (ZnO nanoparticles effectively. Based on our morphological studies, it was revealed that mean particle size was increased while bigger agglomeration of nanoparticles could be observed as the amount of concentration of Mn was increased. Interestingly, it was found that the position of the absorption spectra was shifted towards the lower wavelength (UV region as correlated with the increasing of Mn dopants concentration into ZnO nanoparticles. This result inferred that optimum content of Mn doped into the ZnO nanoparticles was crucial in controlling the visible/UV-responsive of samples. In the present study, 3 mol% of Mn dopants into the ZnO nanoparticles exhibited the better UV as well as visible light-responsive as compared to the other samples. The main reason might be attributed to the modification of electronic structure of ZnO nanoparticles via lattice doping of Mn ions into the lattice, whereas excessive Mn dopants doped on ZnO nanoparticles caused the strong UV-responsive due to the more 3d orbitals in the valence band.

  1. Identification of Fe3+-Li+ complexes in ZnO by means of high-frequency EPR/ENDOR spectroscopy

    Science.gov (United States)

    Kutin, Yu. S.; Mamin, G. V.; Orlinskii, S. B.

    2013-12-01

    Theoretical prediction of a high Curie temperature in ZnO doped with Mn, Fe, and other transition metals has stimulated the investigation of these materials by many research groups. Although charge-compensated Fe3+ centers in ZnO:Fe have been observed by means of EPR and have been known for decades, conclusions on the chemical nature of these defects are still contradictory. Originally, these centers were treated as Fe3+-Li+ complexes with both ions occupying adjacent cationic sites. Recently, however, the centers were interpreted as a substitutional Fe3+ ion with a vacancy at an adjacent zinc or oxygen site (Fe-VZn or Fe-VO). In order to determine the chemical nature of the impurity associated with Fe3+, electron-nuclear double resonance (ENDOR) spectroscopy was used. ENDOR measurements reveal NMR transitions corresponding to nuclei with g-factor gN = 2.171 and spin I = 3/2. This unambiguously shows presence of Li as a charge compensator and also resolves contradictions with the theoretical prediction of the Fe-VO formation energy. The electric field gradients at the 7Li nuclei (within the Fe3+-Li+ complexes) were estimated to be significantly lower than the gradient at undistorted Zn sites.

  2. Study of Doped ZnO Films Synthesized by Combining Vapor Gases and Pulsed Laser Deposition

    Science.gov (United States)

    Zhu, Shen; Su, Ching-Hua; Lehoczky, Sandor L.; George, M. A.

    2000-01-01

    The properties and structure of the ZnO material are similar to those of the GaN. Since an excitonic binding energy of ZnO is about 60 meV, it has strong potential for excitonic lasing at the room temperature. This makes synthesizing ZnO films for applications attractive. However, there are several hurdles in fabricating electro-optical devices from ZnO. One of those is in growing doped p-type ZnO films. Although techniques have been developed for the doping of both p-type and n-type ZnO, this remains an area that can be improved. In this presentation, we will report the experimental results of using both thermal vapor and pulsed laser deposition to grow doped ZnO films. The films are deposited on (0001) sapphire, (001) Si and quartz substrates by ablating a ZnO target. The group III and V elements are introduced into the growth chamber using inner gases. Films are characterized by x-ray diffraction, scanning probe microscopy, energy dispersive spectroscopy, Auger electron spectroscopy, and electrical measurements. The full width at half maximum of theta rocking curves for epitaxial films is less than 0.5 deg. In textured films, it rises to several degrees. Film surface morphology reveals an island growth pattern, but the size and density of these islands vary with the composition of the reactive gases. The electrical resistivity also changes with the doped elements. The relationship between the doping elements, gas composition, and film properties will be discussed.

  3. Surfactant-assisted carbon doping in ZnO nanowires using Poly Ethylene Glycol (PEG)

    Energy Technology Data Exchange (ETDEWEB)

    Amanullah, Malik; Javed, Qurat-ul-Ain, E-mail: Quratulain@sns.nust.edu.pk; Rizwan, Syed

    2016-09-01

    Zinc Oxide (ZnO) provides unique properties owing to its wide bandgap, large resistivity range and possibility to tune the physical properties. The surfactant assisted carbon doping was made possible due to the lowering of surface energy. The ZnO and carbon doped ZnO (C-ZnO) nanowires fabricated by hydrothermal process, Poly Ethylene Glycol (PEG) is used as surfactant in hydrothermal synthesis followed by post growth annealing treatment at 600 °C–700 °C. At 5%–10% of diluted PEG carbon is doped in ZnO. The crystallinity, structural morphology and elemental composition analysis for ZnO and C-ZnO nanowires were carried out using X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy techniques respectively. Carbon doping in ZnO nanowires in the presence of different percentage of surfactant is explained by calculating the change in surface energy with respect to change in PEG molecule concentration. It was found that the surface energy per molecule modulates from 3.92 × 10{sup −8} J/m{sup 2} to 8.16 × 10{sup −7} J/m{sup 2} in the PEG concentration range between 5% and 10%. Our results provides a new theoretical calculations, implemented on real system, to observe the details of PEG-assisted Carbon doping in II-VI semiconductor nanowires. - Highlights: • ZnO and C-ZnO was synthesized by PEG assisted post growth annealing process. • At 5% and 10% of PEG successful synthesis of C-ZnO was found. • XRD, SEM and EDX characterizations confirm the successful synthesis of ZnO and C-ZnO. • Change in surface energy with respect to PEG molecule concentration was calculated.

  4. In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae

    Science.gov (United States)

    Hameed, Abdulrahman Syedahamed Haja; Karthikeyan, Chandrasekaran; Ahamed, Abdulazees Parveez; Thajuddin, Nooruddin; Alharbi, Naiyf S.; Alharbi, Sulaiman Ali; Ravi, Ganasan

    2016-04-01

    Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm‑1 for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls.

  5. In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae.

    Science.gov (United States)

    Hameed, Abdulrahman Syedahamed Haja; Karthikeyan, Chandrasekaran; Ahamed, Abdulazees Parveez; Thajuddin, Nooruddin; Alharbi, Naiyf S; Alharbi, Sulaiman Ali; Ravi, Ganasan

    2016-04-13

    Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm(-1) for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls.

  6. Structural and optoelectronic properties of glucose capped Al and Cu doped ZnO nanostructures

    Directory of Open Access Journals (Sweden)

    Patwari Gunjan

    2016-03-01

    Full Text Available Al and Cu doped ZnO nanoparticles are considered as appropriate for modulation of structural and optoelectronic properties. Al atoms are found to substitute the host Zn whereas Cu dopants mainly segregate in grain boundaries and thereby determine the optical properties. The undoped as well as Al and Cu doped ZnO exhibit spherical well defined particles. The spherical nanoparticles change to rod type structures on co-doping. The average particle size decreases on doping what consequently results in an increment in band gap. Blue shift in UV absorption is governed by the functional group of glucose; further blue shift occurring on metal doping may be attributed to Burstein-Moss effect. PL spectra of doped and undoped ZnO show a dominant near band gap UV emission along with visible emission owing to the defects. The PL peak intensity increases on doping with Cu and Al. The linear I-V characteristics indicate the ohmic behavior of ZnO nanostructures.

  7. Ferromagnetism in laser ablated ZnO and Mn-doped ZnO thin films: A comparative study from magnetization and Hall effect measurements

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen Hoa Hong, E-mail: nguyen.hoahong@univ-tours.f [Laboratoire LEMA, UMR 6157 CNRS - Universite F. Rabelais, Parc de Grandmont, 37200 Tours (France); Chikoidze, Ekaterina; Dumont, Yves [Laboratoire GeMAC, UMR 8635 CNRS - Universite de Versailles, Place A. Briand, 92195 Meudon (France)

    2009-11-15

    Room temperature FM was observed in pristine ZnO thin films grown by pulsed laser deposition on Al{sub 2}O{sub 3} substrates. It seems to originate from other defects but not oxygen vacancies. Magnetization of thinner films is much larger than that of the thicker films, indicating that defects are mostly located at the surface and/or the interface between the film and the substrate. Data on the Fe:ZnO and Mn:ZnO films show that a transition-metal doping does not play any essential role in introducing the magnetism into ZnO. In the case of Mn doping, the magnetic moment could be very slightly enhanced. Hall effect measurements reveal that an incorporation of Mn does not change the carrier type, but decreases the carrier concentration, and increases the Hall mobility, resulting in more resistive Mn:ZnO films. Since no anomalous Hall effect was observed, it is understood that the observed FM is not due to the interaction between the free-carrier and the Mn impurity.

  8. Synthesis of highly efficient antibacterial agent Ag doped ZnO nanorods: Structural, Raman and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Jan, Tariq; Iqbal, Javed, E-mail: javed.saggu@iiu.edu.pk [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University Islamabad (Pakistan); Ismail, Muhammad [Institute of Biomedical and Genetic Engineering (IBGE), Islamabad (Pakistan); Mahmood, Arshad [Nano Devices Labs, National Institute of Lasers and Optronics, Islamabad (Pakistan)

    2014-04-21

    Here, synthesis, structural, morphological, Raman, optical properties and antibacterial activity of undoped and Ag doped ZnO nanorods by chemical co-precipitation technique have been reported. Structural analysis has revealed that Ag doping cannot deteriorate the structure of ZnO and wurtzite phase is maintained. Lattice constants are found to be decreased with the Ag doping. Fourier transform infrared and Raman spectroscopy also confirm the X-ray diffraction results. Scanning electron microscopy results have demonstrated the formation of ZnO nanorods with average diameter and length of 96 nm and 700 nm, respectively. Raman spectroscopy results suggest that the Ag doping enhances the number of defects in ZnO crystal. It has been found from optical study that Ag doping results in positional shift of band edge absorption peak. This is attributed to the successful incorporation of Ag dopant into ZnO host matrix. The antibacterial activity of prepared nanorods has been determined by two different methods and compared to that of undoped ZnO nanorods. Ag doped ZnO nanorods exhibit excellent antibacterial activity as compared to that of undoped ZnO nanorods. This excellent antibacterial activity may be attributed to the presence of oxygen vacancies and Zn{sup 2+} interstitial defects. Our preliminary findings suggest that Ag doped ZnO nanorods can be used externally to control the spreading of infections related with tested bacterial strains.

  9. An Sb-doped p-type ZnO nanowire based random laser diode.

    Science.gov (United States)

    Bashar, Sunayna B; Suja, Mohammad; Morshed, Muhammad; Gao, Fan; Liu, Jianlin

    2016-02-12

    An electrically pumped Sb-doped ZnO nanowire/Ga-doped ZnO p-n homojunction random laser is demonstrated. Catalyst-free Sb-doped ZnO nanowires were grown on a Ga-doped ZnO thin film on a Si substrate by chemical vapor deposition. The morphology of the as-grown titled nanowires was observed by scanning electron microscopy. X-ray photoelectron spectroscopy results indicated the incorporation of Sb dopants. Shallow acceptor states of Sb-doped nanowires were confirmed by photoluminescence measurements. Current-voltage measurements of ZnO nanowire structures assembled from p- and n-type materials showed a typical p-n diode characteristic with a threshold voltage of about 7.5 V. Very good photoresponse was observed in the UV region operated at 0 V and different reverse biases. Random lasing behavior with a low-threshold current of around 10 mA was demonstrated at room temperature. The output power was 170 nW at 30 mA.

  10. Effect of cobalt doping on structural and optical properties of ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, J.; Chanda, A., E-mail: anupamamatsc@gmail.com; Gupta, S.; Shukla, P. [Department of Physics, Dr. Harisingh Gour University, Sagar, M.P-470003 (India); Chandra, V. [Department of Chemistry, Dr. Harisingh Gour University, Sagar, M.P-470003 (India)

    2016-05-23

    Cobalt doped ZnO nanoparticles of uniform sizes were prepared by a chemical method using ZnCl{sub 2} and NaOH as the source materials. The formation of Co-doped ZnO nanoparticles was confirmed by transmission electron microscopy (TEM), high resolution TEM (HR-TEM) and selected area electron diffraction (SAED) studies. The optical properties of obtained products were examined using room temperature UV-visible and FTIR spectroscopy. SAED of cobalt doped ZnO nanoparticles shows homogeneous distribution of nanoparticles with hexagonal structure. The HRTEM image of the Co-doped ZnO nanoparticles reveals a clear lattice spacing of 0.52 nm corresponding to the interplanar spacing of wurtzite ZnO (002) plane. The absorption band at 857 cm{sup −1} in FTIR spectra confirmed the tetrahedral coordination of Zn and a shift of absorption peak to shorter wavelength region and decrease in absorbance with Co doping.is observed in UV-Visible spectra.

  11. Structural, electronic and optical properties of Cu-doped ZnO: experimental and theoretical investigation

    Science.gov (United States)

    Horzum, S.; Torun, E.; Serin, T.; Peeters, F. M.

    2016-06-01

    Experiments are supplemented with ab initio density functional theory (DFT) calculations in order to investigate how the structural, electronic and optical properties of zinc oxide (ZnO) thin films are modified upon Cu doping. Changes in characteristic properties of doped thin films, that are deposited on a glass substrate by sol-gel dip coating technique, are monitored using X-ray diffraction (XRD) and UV measurements. Our ab initio calculations show that the electronic structure of ZnO can be well described by DFT+U/? method and we find that Cu atom substitutional doping in ZnO is the most favourable case. Our XRD measurements reveal that the crystallite size of the films decrease with increasing Cu doping. Moreover, we determine the optical constants such as refractive index, extinction coefficient, optical dielectric function and optical energy band gap values of the films by means of UV-Vis transmittance spectra. The optical band gap of ZnO the thin film linearly decreases from 3.25 to 3.20 eV at 5% doping. In addition, our calculations reveal that the electronic defect states that stem from Cu atoms are not optically active and the optical band gap is determined by the ZnO band edges. Experimentally observed structural and optical results are in good agreement with our theoretical results.

  12. Highly efficient photocatalytic degradation of organic dyes by Cu doped ZnO nanostructures.

    Science.gov (United States)

    Kuriakose, Sini; Satpati, Biswarup; Mohapatra, Satyabrata

    2015-10-14

    Copper doped ZnO nanostructures have been synthesized by a facile wet chemical method. Structural properties of as-synthesized nanomaterials have been studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) with energy dispersive X-ray spectroscopy, while UV-visible absorption spectroscopy and Raman spectroscopy have been used to study their optical properties. Sunlight driven photocatalytic degradation of methylene blue (MB) and methyl orange (MO) dyes in water was used to evaluate the photocatalytic activities of Cu doped ZnO nanostructures using UV-visible absorption spectroscopy. The results showed that there is an optimum Cu doping level which leads to the highly enhanced photocatalytic activity of Cu doped ZnO nanostructures, as compared to pure ZnO nanostructures. A mechanism for the enhanced photocatalytic activity of Cu-ZnO nanostructures is tentatively proposed. The enhanced photocatalytic activity of Cu-ZnO nanostructures is attributed to the combined effects of improved separation of photogenerated charge carriers due to optimal Cu doping in ZnO nanostructures and the formation of ZnO-CuO nanoheterojunctions.

  13. Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

    Science.gov (United States)

    Babar, A. R.; Deshamukh, P. R.; Deokate, R. J.; Haranath, D.; Bhosale, C. H.; Rajpure, K. Y.

    2008-07-01

    Zinc oxide (ZnO) and ZnO : Ga films have been deposited by the spray pyrolysis method onto preheated glass substrates using zinc acetate and gallium nitrate as precursors for Zn and Ga ions, respectively. The effect of Ga doping on the structural, morphological, optical and electrical properties of sprayed ZnO thin films were investigated using x-ray diffraction (XRD), scanning electron microscopy, optical absorption, photoluminescence (PL) and Hall effect techniques. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were oriented along the (0 0 2) plane. Room temperature PL measurements indicate that the deposited films exhibit proper doping of Ga in ZnO lattice. The average transparency in the visible range was around ~85-95% for typical thin film deposited using 2 at% gallium doping. The optical band gap increased from 3.31 to 3.34 eV with Ga doping of 2 at%. The addition of gallium induces a decrease in electrical resistivity of the ZnO : Ga films up to 2 at% gallium doping. The highest figure of merit observed in this present study was 3.09 × 10-3 cm2 Ω-1.

  14. Gallium doping in transparent conductive ZnO thin films prepared by chemical spray pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Babar, A R; Deshamukh, P R; Deokate, R J; Bhosale, C H; Rajpure, K Y [Electrochemical Materials Laboratory, Department of Physics, Shivaji University, Kolhapur 416 004 (India); Haranath, D [National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110 012 (India)], E-mail: rajpure@yahoo.com

    2008-07-07

    Zinc oxide (ZnO) and ZnO : Ga films have been deposited by the spray pyrolysis method onto preheated glass substrates using zinc acetate and gallium nitrate as precursors for Zn and Ga ions, respectively. The effect of Ga doping on the structural, morphological, optical and electrical properties of sprayed ZnO thin films were investigated using x-ray diffraction (XRD), scanning electron microscopy, optical absorption, photoluminescence (PL) and Hall effect techniques. XRD studies reveal that films are polycrystalline with hexagonal (wurtzite) crystal structure. The thin films were oriented along the (0 0 2) plane. Room temperature PL measurements indicate that the deposited films exhibit proper doping of Ga in ZnO lattice. The average transparency in the visible range was around {approx}85-95% for typical thin film deposited using 2 at% gallium doping. The optical band gap increased from 3.31 to 3.34 eV with Ga doping of 2 at%. The addition of gallium induces a decrease in electrical resistivity of the ZnO : Ga films up to 2 at% gallium doping. The highest figure of merit observed in this present study was 3.09 x 10{sup -3} cm{sup 2} {omega}{sup -1}.

  15. Ultrasonic-Assisted Synthesis, Characterization, and Optical Properties of Sb Doped ZnO and Their Photocatalytic Activities

    OpenAIRE

    Anukorn Phuruangrat; Waipawan Kongpet; Oranuch Yayapao; Budsabong Kuntalue; Somchai Thongtem; Titipun Thongtem

    2014-01-01

    Sb doped ZnO nanostructures were synthesized by an ultrasonic-assisted method. Effect of Sb dopant on the structure, morphology, and composition of as-synthesized Sb doped ZnO nanostructures was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, and transmission electron microscopy (TEM). All samples were identified to wurtzite hexagonal ZnO structure. UV-visible spectra of the as-synthesized 3% Sb doped ZnO sample exhibit ...

  16. Structural defects and photoluminescence studies of sol-gel prepared ZnO and Al-doped ZnO films

    Science.gov (United States)

    Sandeep, K. M.; Bhat, Shreesha; Dharmaprakash, S. M.

    2016-11-01

    ZnO and Al-doped ZnO (AZO) films were synthesized using sol-gel spin-coating method. The powder XRD analysis revealed the stress relaxation mechanism upon Al doping in ZnO film. The reduction in the imaginary part of the dielectric constant and suppression of deep level acceptor type octahedral oxygen interstitial defects account for the reduction in carrier concentration in AZO with respect to ZnO. Electrical conductivity measurements and grain boundary conduction model are used to quantify the carrier concentration. From the Commission Internationale d'Eclairge diagram of ZnO and AZO, color parameters like dominant wavelength, color purity and luminosity are determined and reported for the first time. The prepared ZnO and AZO films show considerable blue emission. These films can be used for white light generation.

  17. Large lateral photovoltaic effect observed in nano Al-doped ZnO films.

    Science.gov (United States)

    Lu, Jing; Wang, Hui

    2011-07-18

    Zinc oxide (ZnO), including a variety of metal-doped ZnO, as one kind of most important photoelectric materials, has been widely investigated and received enormous attention for a series of applications. In this work, we report a new finding which we call as lateral photovoltaic effect (LPE) in a nano Al-doped ZnO (ZAO) film based on ZAO/SiO2/Si homo-heterostructure. This large and stable LPE observed in ZAO is an important supplement to the existing ZnO properties. In addition, all data and analyses demonstrate ZAO film can also be a good candidate for new type position-sensitive detector (PSD) devices.

  18. Synthesis and Optical Properties of Ce-doped ZnO

    Institute of Scientific and Technical Information of China (English)

    YANG Jing-hai; WEI Mao-bin; LIU Fu-zhu; GAO Ming; ZHANG Yong-jun; YANG Li-li; LANG Ji-hui; WANG Dan-dan; WANG Ya-xin; LIU Hui-lian; FAN Hou-gang

    2008-01-01

    Abstract ZnO nanorods were synthesized using the sol-gel method, and the effects of annealing temperature and Ce doping on the morphologies and optical properties of ZnO nanostructures were investigated in detail. The XRD measurements showed that the as-synthesized ZnO nanostructures had a hexagonal wurtzite structure. SEM images showed that uniform nanorods formed at 900 ℃. Photoluminescence measurements showed an ultraviolet emission peak and a relatively broad visible light emission peak for the samples sintered at different temperatures. The UV emission peak bathochromically shifted when the annealing temperature rose from 850 to 1000 ℃. Ce doping decreased the synthesized temperature of the ZnO nanorods to 500 ℃, and the UV peaks hypsochromically shifted.

  19. Effect of chlorine doping on electrical and optical properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Chikoidze, E. [Groupe d' Etude de la Matiere Condensee (GEMaC), CNRS, Universite de Versailles-Saint-Quentin, 1 Place Aristide Briand. 92195 Meudon Cedex (France)], E-mail: Ekaterina.chikoidze@cnrs-bellevue.fr; Nolan, M.; Modreanu, M. [Tyndall National Institute, University College Cork, Lee Maltings, Prospect Row, Cork (Ireland); Sallet, V.; Galtier, P. [Groupe d' Etude de la Matiere Condensee (GEMaC), CNRS, Universite de Versailles-Saint-Quentin, 1 Place Aristide Briand. 92195 Meudon Cedex (France)

    2008-09-30

    Chlorine doped ZnO thin films were grown by metal-organic chemical vapour deposition (MOCVD) on sapphire and fused silica substrates. Chlorine is incorporated by substitution of oxygen and acts as a donor, leading to an increase of electron concentration. Transport properties were studied for ZnO thin films with different chlorine content. Hall effect measurements show an increase of electron carrier concentration and a decrease of electron mobility upon increasing the amount of chlorine incorporated in ZnO. The lowest resistivity {rho} = 3.6 x 10{sup -3} {omega} cm was obtained for layers deposited on sapphire substrate. UV-VIS-NIR spectroscopy has been used for the study of optical properties. For all samples, the optical transmittance in the visible range is greater than 80%. First principles computations were applied in order to examine the change in the band gap of ZnO with Cl doping.

  20. Synthesis of yttrium doped nanocrystalline ZnO and its photocatalytic activity in methylene blue degradation

    OpenAIRE

    2016-01-01

    Yttrium doped zinc oxide was prepared by microwave irradiation of Y (NO3)3·6H2O and Zn(NO3)2·4H2O as precursors, in ethanol–water medium. Highly polar ethanol–water medium (30/70, v/v) with hexamine and urea assist the formation of ZnO nuclei very rapidly in a specific fashion. Furthermore, Y3+ ions infiltration into Zn(OH)2 precipitate was facilitated by microwaves (2.45 GHz, 950 W). Yttrium doped nanocrystalline ZnO (ZnO-99 and ZnO-95) was formed with 1 and 5 mol% yttrium precursor. The pow...

  1. EPR investigation of pure and Co-doped ZnO oriented nanocrystals

    Science.gov (United States)

    Savoyant, A.; Alnoor, H.; Bertaina, S.; Nur, O.; Willander, M.

    2017-01-01

    Pure and cobalt-doped zinc oxide aligned nanorods have been grown by the low-temperature (90 °C) aqueous chemical method on amorphous ZnO seed layer, deposited on a sapphire substrate. High crystallinity of these objects is demonstrated by the electron paramagnetic resonance investigation at liquid helium temperature. The successful incorporation of Co2+ ions in substitution of Zn2+ ones in the ZnO matrix has also been confirmed. A drastic reduction of intrinsic ZnO nanorods core defects is observed in the Co-doped samples, which enhances the structural quality of the NRs. The quantification of substitutional Co2+ ions in the ZnO matrix is achieved by comparison with a reference sample. The findings in this study indicate the potential of using the low-temperature aqueous chemical approach for synthesizing material for spintronics applications.

  2. Effect of metal-ion doping on the optical properties of nanocrystalline ZnO thin films

    Science.gov (United States)

    Mendoza-Galván, A.; Trejo-Cruz, C.; Lee, J.; Bhattacharyya, D.; Metson, J.; Evans, P. J.; Pal, U.

    2006-01-01

    Optical properties of metal (Al, Ag, Sb, and Sn)-ion-implanted ZnO films have been studied by ultraviolet-visible spectroscopy and spectroscopic ellipsometric techniques. The effects of metal-ion doping on the optical band gap (Eg), refractive index (n), and extinction coefficient (k) of nanocrystalline ZnO films have been studied for the similar implantation dose of all the metal ions. The ellipsometric spectra of the ion-implanted samples could be well described by considering an air/roughness/ZnO-M (layer 1)/ZnO (layer 2)/glass model. The band gap of ZnO films increases with Al ion doping and decreases with doping of Ag, Sb, and Sn ions. The refractive index of ZnO films in the visible spectral region increases substantially on Sb and Sn ion doping, while it decreases to some extent with Al ion doping.

  3. Synthesis of Al doped ZnO nanoparticles by aqueous coprecipitation

    OpenAIRE

    Giovannelli, Fabien; Ngo Ndimba, P.; Diaz-Chao, P.; Motelica-Heino, Mikael; Raynal, P.I.; Autret, C.; Delorme, F.

    2014-01-01

    International audience; Al-doped ZnO particles were obtained by a simple route: soda addition in aqueous cationic solution. The effects of temperature, hydrolysis duration, reagent concentration and time were investigated. A non-topotactic reaction mechanism, involving firstly the precipitation of various hydroxide compounds depending on the route (low or high pH), followed by the dissolution-recrystallization of the hydroxide species into ZnO was demonstrated. The Al concentration in the fin...

  4. Study of cobalt doping on structural and luminescence properties of nanocrystalline ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Husain, Shahid, E-mail: s.husain@lycos.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Alkhtaby, Lila A.; Bhat, Irshad [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Giorgetti, Emilia; Zoppi, Angela [Istituto dei Sistemi Complessi ISC – CNR Sezione di Firenze, Sesto Fiorentino 50019 Firenze (Italy); Muniz Miranda, Maurizio [Department of Chemistry, University of Firenze, Sesto Fiorentino 50019 Firenze (Italy)

    2014-10-15

    We have synthesized the Zn{sub 1−x}Co{sub x}O (x=0.01, 0.02, 0.03 and 0.05) nanoparticles by the sol–gel method. The adopted sol gel method needs no reaction agent to control the formation of precipitation except ammonia that is used to control the pH. These samples are characterized using x-ray diffraction (XRD), Scanning Electron Microscope (SEM), Ultraviolet/Visible(UV/Vis) spectroscopy, Fluorescence spectroscopy, Raman spectroscopy and Fourier transform infra red (FTIR) spectroscopy. The x-ray diffraction patterns show that all the sample are formed in single phase with a complete solubility of Co ions in the ZnO matrix. SEM micrographs show that the Co doped ZnO nanoparticles are hexagonal with wurtzite structure. We have found slight agglomeration of naoparticles for higher concentration of cobalt. Energy dispersive x-ray spectroscopy (EDS) confirms the presence of Zn, Co and O elements. The particle sizes range between 50 and 60 nm. We have observed a decrease in fluorescence intensity with the increase in Co doping but all the Co doped samples show higher value of intensity as compared to pure ZnO in the visible range of spectrum. Raman spectroscopy reveals that the characteristic intense band of ZnO at 435 cm{sup −1} exhibits a decrease in intensity and slightly red shifts with the Co doping. The overall intensity of the samples shows a decrease with the increase in Co doping. FTIR spectra exhibit that the Zn-O band at ∼497 cm{sup −1} for pure ZnO is shifted to lower frequency with the increase in Co doping. - Highlights: • Cobalt doped ZnO nanoparticles are synthesized through sol gel process. • All the samples show wurtzite crystal symmetry with particle sizes are found to be in the range of from 50 to 60 nm. • The energy band-gap estimated using UV/Vis spectra is found to increase with the Co doping. • Raman spectra reveals that characteristic intense band of ZnO at 436 cm{sup −1} exhibit a red shift with the cobalt doping.

  5. Effect of Co-doping content on hydrothermal derived ZnO array films

    Energy Technology Data Exchange (ETDEWEB)

    He Xinhua, E-mail: imxhhe@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Department of Information Systems, City University of Hong Kong (Hong Kong); Yang Hu; Chen Zhiwu [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Liao, Stephen S Y, E-mail: issliao@cityu.edu.hk [Department of Information Systems, City University of Hong Kong (Hong Kong)

    2012-08-01

    Cobalt doped ZnO films are synthesised using a hydrothermal process. The effect of Co{sup 2+} concentration on morphology, phase composition, crystallisation and spectroscopic characteristics of ZnO films is investigated. The results indicate that both the structure and morphology of the ZnO films evolve with the concentration of cobalt ions incorporated into the lattice. In the presence of a small amount of Co{sup 2+} ions, films are formed that comprise hexagonal ZnO nanorods, oriented with the c-axis perpendicular to the substrate. With increasing amount of Co{sup 2+}, cracks in the ZnO nanorods can be observed and growth in the [0 0 1] direction is significantly inhibited. When the Co{sup 2+} concentration exceeds 0.010 M, ZnO rods with the typical hexagonal structure are no longer observed and instead, ZnO films comprising close-packed grains with an irregular polygonal structure are formed. The epitaxial growth of ZnO films is nearly completely inhibited when the concentration of Co{sup 2+} is increased above 0.050 M. This behaviour can be explained by the selective adsorption of the organic substances in the solution onto the (0 0 1) ZnO crystal face, thus inhibiting growth in the [0 0 1] direction and disrupting the crystallisation of ZnO films. Increasing the Co content deteriorates the crystallisation of ZnO rods and increases tensile stresses present in the ZnO films.

  6. Stability of the Fe3 +  state in ZnO

    DEFF Research Database (Denmark)

    Naidoo, D.; Gunnlaugsson, Haraldur Pall; Mølholt, T.E.

    2013-01-01

    are dominated by the Fe3 +  state exhibiting a slow paramagnetic relaxation. We show that the Fe3 +  state in ZnO saturated by 760 K or storage at room temperature for 12 months, after which they show dominantly the Fe2...... +  state for diffusion and/or annihilation of implantation-induced defects....

  7. Al-doped ZnO seed layer-dependent crystallographic control of ZnO nanorods by using electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hyo-Soo; Choi, Nak-Jung [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Kim, Kyoung-Bo [Department of Metallurgical and Materials Engineering, Inha Technical College, Incheon 402-752 (Korea, Republic of); Kim, Moojin [Department of Renewable Energy, Jungwon University, Goesan-gun, Chungbuk 367-805 (Korea, Republic of); Lee, Sung-Nam, E-mail: snlee@kpu.ac.kr [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of)

    2016-10-15

    Highlights: • Polar and semipolar ZnO NRs were successfully achieved by hydrothermal synthesis. • Semipolar and polar ZnO NRs were grown on ZnO and AZO/m-sapphire, respectively. • Al % of AZO/m-sapphire enhanced the lateral growth rate of polar ZnO NRs. - Abstract: We investigated the effect of an Al-doped ZnO film on the crystallographic direction of ZnO nanorods (NRs) using electrochemical deposition. From high-solution X-ray diffraction measurements, the crystallographic plane of ZnO NRs grown on (1 0 0) ZnO/m-plane sapphire was (1 0 1). The surface grain size of the (100) Al-doped ZnO (AZO) film decreased with increasing Al content in the ZnO seed layer, implying that the Al dopant accelerated the three-dimensional (3D) growth of the AZO film. In addition, it was found that with increasing Al doping concentration of the AZO seed layer, the crystal orientation of the ZnO NRs grown on the AZO seed layer changed from [1 0 1] to [0 0 1]. With increasing Al content of the nonpolar (1 0 0) AZO seed layer, the small surface grains with a few crystallographic planes of the AZO film changed from semipolar (1 0 1) ZnO NRs to polar (0 0 1) ZnO NRs due to the increase of the vertical [0 0 1] growth rate of the ZnO NRs owing to excellent electrical properties.

  8. Room temperature ferromagnetism in Mg-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jaspal, E-mail: jaspal0314@gmail.com; Vashihth, A. [Department of Applied Sciences, Chandigarh University, Gharuan, Mohali-140413 (India); Gill, Pritampal Singh; Verma, N. K. [Nano Research Lab, School of Physics and Materials Science, Thapar University, Patiala-147 004 (India)

    2015-06-24

    Zn{sub 1-x}Mg{sub x}O (x = 0, 0,10) nanoparticles were successfully synthesized using sol-gel method. X-ray diffraction (XRD) confirms that the synthesized nanoparticles possess wurtzite phase having hexagonal structure. Morphological analysis was carried out using transmission electron microscopy (TEM) which depicts the spherical morphology of ZnO nanoparticles. Energy dispersive spectroscopy (EDS) showed the presence of Mg in ZnO nanoparticles. Electron spin resonance (ESR) signal was found to be decreasing with increasing of Mg-doping concentration. The room temperature ferromagnetism was observed in undoped and Mg-doped ZnO nanoparticles. The increase of Mg-doping concentration resulted in decrease of saturation magnetization value which could be attributed to decrease of oxygen vacancies present in host nanoparticles.

  9. Effect of Ag Doping on Optical and Electrical Properties of ZnO Thin Films

    Institute of Scientific and Technical Information of China (English)

    XU Jin; ZHANG Zi-Yu; ZHANG Yang; LIN Bi-Xia; FU Zhu-Xi

    2005-01-01

    @@ ZnO thin films were prepared on p-type Si (100) substrates by the sol-gel process. The influence of Ag doping at a content of 0.002 % on the photoluminescence and current-voltage (Ⅰ - Ⅴ) characteristics of ZnO thin films has been investigated. It is found that Ag doping leads to a pronounced increase in the intensity of near band edge emission at 3.23 eV and a remarkable red shift of the visible broadband at room temperature. The Ⅰ - Ⅴ characteristics of ZnO/p-Si hetero junctions are also changed. These results could be explained by Ag substituting for Zn in Ag doped ZnO thin films.

  10. Synthesis and Characterization of Transition Metals Doped ZnO Nanorods

    Institute of Scientific and Technical Information of China (English)

    G. Murugadoss

    2012-01-01

    Different morphologies of undoped and transition metals (Mn, Co and Ni) doped one-dimensional (ID) ZnO nanocrystals were successfully synthesized by chemical method in an air atmosphere using polyvinylpyrrolidone (PVP) as a surfactant. The structure and optical properties were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), ultraviolet visible (UV-vis) absorption spectra and photoluminescence (PL) spectra. The doped ZnO nanorods exhibited a blue-shifted band gap and enhanced ultraviolet (UV) emission. In addition defect related emission was observed for the doped ZnO.

  11. Role of Ni doping on transport properties of ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Dar, Tanveer Ahmad, E-mail: tanveerphysics@gmail.com; Agrawal, Arpana; Sen, Pratima [Laser Bhawan, School Of Physics, Devi Ahilaya University Takshashila Campus Khandwa Road Indore, Indore-452001 (India)

    2015-06-24

    Nickel doped (Ni=0.05) and undoped Zinc Oxide (ZnO) thin films have been prepared by Pulsed laser deposition (PLD) technique. The structural analysis of the films was done by X-ray diffraction (XRD) studies which reveal absence of any secondary phase in the prepared samples. UV transmission spectra show that Ni doping reduces the transparency of the films. X-ray Photoelectron spectroscopy (XPS) also shows the presence of metallic Ni along with +2 oxidation state in the sample. Low temperature magneto transport properties of the ZnO and NiZnO films are also discussed in view of Khosla fisher model. Ni doping in ZnO results in decrease in magnitude of negative MR.

  12. Gas sensing properties of Al-doped ZnO for UV-activated CO detection

    Science.gov (United States)

    Dhahri, R.; Hjiri, M.; El Mir, L.; Bonavita, A.; Iannazzo, D.; Latino, M.; Donato, N.; Leonardi, S. G.; Neri, G.

    2016-04-01

    Al-doped ZnO (AZO) samples were prepared using a modified sol-gel route and charaterized by means of trasmission electron microscopy, x-ray diffraction and photoluminescence analysis. Resistive planar devices based on thick films of AZO deposited on interdigitated alumina substrates were fabricated and investigated as UV light activated CO sensors. CO sensing tests were performed in both dark and illumination condition by exposing the samples to UV radiation (λ  =  400 nm).Under UV light, Al-doped ZnO gas sensors operated at lower temperature than in dark. Furthermore, by photoactivation we also promoted CO sensitivity and made signal recovery of AZO sensors faster. Results demonstrate that Al-doped ZnO might be a promising sensing material for the detection of CO under UV illumination.

  13. Variable range hopping crossover and magnetotransport in PLD grown Sb doped ZnO thin film

    Science.gov (United States)

    Mukherjee, Joynarayan; Mannam, Ramanjaneyulu; Ramachandra Rao, M. S.

    2017-04-01

    We report on the variable range hopping (VRH) crossover in the electrical transport of Sb doped ZnO (SZO) thin film. Structural, chemical, electrical and magnetotransport properties were carried out on SZO thin film grown by pulsed laser deposition. X-photoelectron spectroscopy study confirms the presence of both Sb3+(33%) and Sb5+(67%) states. Sb doped ZnO thin film shows n-type behavior which is attributed to the formation of SbZn and/or SbZn–VZn defect complex. Temperature dependent resistivity measurement showed that in a low temperature regime (doped ZnO thin films is explained by the Khosla and Fischer model.

  14. Highly doped ZnO films deposited by spray-pyrolysis. Design parameters for optoelectronic applications

    Energy Technology Data Exchange (ETDEWEB)

    Garcés, F.A., E-mail: felipe.garces@santafe-conicet.gov.ar [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Budini, N. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Schmidt, J.A.; Arce, R.D. [Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, Santa Fe S3000GLN (Argentina); Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santiago del Estero 2829, Santa Fe S3000AOM (Argentina)

    2016-04-30

    Synthesis and preparation of ZnO films are relevant subjects for obtaining transparent and conducting layers with interesting applications in optoelectronics and photovoltaics. Optimization of parameters such as dopant type and concentration, deposition time and substrate temperature is important for obtaining ZnO layers with optimal properties. In this work we present a study about the induced effects of deposition time on optical and electrical properties of ZnO thin films. These films were deposited by spray pyrolysis of a suitable Zn precursor, obtained through the sol–gel method. The deposition time has direct incidence on internal stress in the crystal structure, generating defects that may affect transparency and electrical transport into the layers. We performed mosaicity measurements, through X-ray diffraction, and used it as a tool to get an insight on structural characteristics and homogeneity of ZnO layers. Also, through this technique, we analyzed thickness and doping effects on crystallinity and carrier transport properties. - Highlights: • Al-doped ZnO films with high conductivity and moderate Hall mobility were obtained. • Mosaicity between crystalline domains increased with film thickness. • Lattice parameters a and c diminished linearly as a function of Al concentration. • First steps for developing porous silicon/doped ZnO heterojunctions were presented.

  15. Structural and Optical Properties of Eu Doped ZnO Nanorods prepared by Pulsed Laser Deposition

    KAUST Repository

    Alarawi, Abeer

    2014-06-23

    Nano structured wide band gap semiconductors have attracted attention of many researchers due to their potential electronic and optoelectronic applications. In this thesis, we report successful synthesis of well aligned Eu doped ZnO nano-rods prepared, for the first time to our knowledge, by pulsed laser deposition (PLD) without any catalyst. X-ray diffraction (XRD) patterns shows that these Eu doped ZnO nanorods are grown along the c-axis of ZnO wurtzite structure. We have studied the effect of the PLD growth conditions on forming vertically aligned Eu doped ZnO nanorods. The structural properties of the material are investigated using a -scanning electron microscope (SEM). The PLD parameters must be carefully controlled in order to obtain c-axis oriented ZnO nanorods on sapphire substrates, without the use of any catalyst. The experiments conducted in order to identify the optimal growth conditions confirmed that, by adjusting the target-substrate distance, substrate temperature, laser energy and deposition duration, the nanorod size could be successfully controlled. Most importantly, the results indicated that the photoluminescence (PL) properties reflect the quality of the ZnO nanorods. These parameters can change the material’s structure from one-dimensional to two-dimensional however the laser energy and frequency affect the size and the height of the nanorods; the xygen pressure changes the density of the nanorods.

  16. Impressive enhancement in the cell performance of ZnO nanorod-based perovskite solar cells with Al-doped ZnO interfacial modification.

    Science.gov (United States)

    Dong, Juan; Zhao, Yanhong; Shi, Jiangjian; Wei, Huiyun; Xiao, Junyan; Xu, Xin; Luo, Jianheng; Xu, Jing; Li, Dongmei; Luo, Yanhong; Meng, Qingbo

    2014-11-11

    Al-doped ZnO (AZO) modified ZnO nanorods have been applied in CH3NH3PbI3 perovskite solar cells, which can show a positive effect on open circuit voltage and power conversion efficiency. The average power conversion efficiency is improved from 8.5% to 10.07% and the maximum efficiency reaches 10.7%.

  17. Characterization of ZnO Thin Films Doped with Natrium by Sol-Gel Method

    OpenAIRE

    gareso, paulus lobo; Syuhada, Nurnadiyah; Rauf, Nurlaela; Juarlin, Eko; Sugianto; Maddu, Akhirruddin

    2014-01-01

    This article will be presented in the 4Th International conference on Theoretical and applied Physics in Bali for 16-17 October 2014 The characterization of ZnO films doped with natrium by sol-gel spin coating method have been studied using the optical transmittance UV-Vis and X-ray diffraction (X-RD) measurements. The ZnO films were prepared using zinc acetate dehydrate (Zn(CH3COO)2.2H2O), ethanol, and diethanolamine (DEA) as the precursor, solvent, and stabilizer, respectively. For ZnO d...

  18. IMPROVEMENT OF THE CRYSTALLINITY AND OPTICAL PARAMETERS OF ZnO FILM WITH ALUMINUM DOPING

    OpenAIRE

    Ilican, Saliha

    2016-01-01

    In this study, the undoped and Aluminum (Al) doped (1% and 3%) zinc oxide (ZnO) films were prepared by sol gel method via spin coating onto glass substrates. To investigate the structural and optical properties of the films, it was used to X-ray diffractometer and UV-vis spectrophotometer, respectively. The prepared ZnO films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation according to the (002) plane. The crystalline quality of ZnO film was improved by...

  19. Preparation and antibacterial properties of titanium-doped ZnO from different zinc salts.

    Science.gov (United States)

    Sun, Tong; Hao, Han; Hao, Wen-Ting; Yi, Shu-Min; Li, Xue-Peng; Li, Jian-Rong

    2014-02-27

    To research the relationship of micro-structures and antibacterial properties of the titanium-doped ZnO powders and probe their antibacterial mechanism, titanium-doped ZnO powders with different shapes and sizes were prepared from different zinc salts by alcohothermal method. The ZnO powders were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), and the antibacterial activities of titanium-doped ZnO powders on Escherichia coli and Staphylococcus aureus were evaluated. Furthermore, the tested strains were characterized by SEM, and the electrical conductance variation trend of the bacterial suspension was characterized. The results indicate that the morphologies of the powders are different due to preparation from different zinc salts. The XRD results manifest that the samples synthesized from zinc acetate, zinc nitrate, and zinc chloride are zincite ZnO, and the sample synthesized from zinc sulfate is the mixture of ZnO, ZnTiO3, and ZnSO4 · 3Zn (OH)2 crystal. UV-vis spectra show that the absorption edges of the titanium-doped ZnO powders are red shifted to more than 400 nm which are prepared from zinc acetate, zinc nitrate, and zinc chloride. The antibacterial activity of titanium-doped ZnO powders synthesized from zinc chloride is optimal, and its minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) are lower than 0.25 g L-1. Likewise, when the bacteria are treated by ZnO powders synthesized from zinc chloride, the bacterial cells are damaged most seriously, and the electrical conductance increment of bacterial suspension is slightly high. It can be inferred that the antibacterial properties of the titanium-doped ZnO powders are relevant to the microstructure, particle size, and the crystal. The powders can damage the cell

  20. Morphological properties of Al-doped ZnO nano/microstructures

    Science.gov (United States)

    Kim, Kyung Ho; Umakoshi, Tomoyuki; Abe, Yoshio; Kawamura, Midori; Kiba, Takayuki

    2016-03-01

    We discussed the morphological properties of Al-doped zinc oxide (Al-ZnO) microrods grown on a ZnO seed layer and precipitation particles and compared them with undoped ZnO samples. The ZnO nanorods grown on a ZnO seed layer were dense and perpendicular to the surface of the substrate, i.e., fluorine-doped tin oxide (FTO). In contrast the Al-ZnO grew as larger microrods, and the rods were sparsely and obliquely arranged. Precipitation particles synthesized in the ZnO solution through homogeneous nucleation had flower-like structures assembled from the rods and individual rods with lengths of several micrometers. Al-ZnO precipitation particles consisted of rods with length of several micrometers and hexagonal nanoplates. Fourier transform infrared (FTIR) analysis results showed that the rods and precipitation particles had the good chemical properties of ZnO. Both size and morphology of the rods could be effectively controlled by adding aluminum nitrate (Al(NO3)3) as dopant in the ZnO rod solution.

  1. Thermoelectric properties of Al-doped ZnO: experiment and simulation

    Science.gov (United States)

    Jantrasee, S.; Moontragoon, P.; Pinitsoontorn, S.

    2016-09-01

    Advancement in doping other elements, such as Ce, Dy, Ni, Sb, In and Ga in ZnO[1], have stimulated great interest for high-temperature thermoelectric application. In this work, the effects of Al-doping in a ZnO system on the electronic structure and thermoelectric properties are presented, by experiment and calculation. Nanosized powders of Zn1-x Al x O (x = 0,0.01, 0.02, 0.03 and 0.06) were synthesized by hydrothermal method. From XRD results, all samples contain ZnO as the main phase and ZnAl2O4 (spinel phase) peaks were visible when Al additive concentrations were just 6 at%. The shape of the samples changed and the particle size decreased with increasing Al concentration. Seebeck coefficients, on the other hand, did not vary significantly. They were negative and the absolute values increased with temperature. However, the electrical resistivity decreased significantly for higher Al content. The electronic structure calculations were carried out using the open-source software package ABINIT[2], which is based on DFT. The energy band gap, density of states of Al-doped ZnO were investigated using PAW pseudopotential method within the LDA + U. The calculated density of states was then used in combination with the Boltzmann transport equation[3] to calculate the thermoelectric parameters of Al-doped ZnO. The electronic band structures showed that the position of the Fermi level of the doped sample was shifted upwards in comparison to the undoped one. After doping Al in ZnO, the energy band gap was decreased, Seebeck coefficient and electrical conductivity were increased. Finally, the calculated results were compared with the experimental results. The good agreement of thermoelectric properties between the calculation and the experimental results were obtained.

  2. Preparation of Ni doped ZnO thin films by SILAR and their characterization

    Science.gov (United States)

    Mondal, S.; Mitra, P.

    2013-02-01

    Pure and nickel (Ni) doped zinc oxide (NZO) thin films were deposited on glass substrates from ammonium zincate bath using successive ion layer adsorption and reaction (SILAR). Characterization techniques such as XRD, TEM, SEM and EDX were utilized to investigate the effect of Ni doping on the microstructure of Ni:ZnO thin films. Structural characterization by X-ray diffraction reveals the polycrystalline nature of the films. Particle size shows slightly decreasing trend with increasing nickel impurification. The average particle size for pure ZnO is 22.75 nm and it reduces to 20.51 nm for 10 % Ni doped ZnO. Incorporation of Ni was confirmed from elemental analysis using EDX. The value of fundamental absorption edge is 3.23 eV for pure ZnO and it decreases to 3.19 eV for 10 % Ni:ZnO. The activation energy barrier value to electrical conduction process increases from 0.261 eV for pure ZnO to 0.293 eV for 10 % Ni doped ZnO.

  3. Hydrothermal fabrication of selectively doped organic assisted advanced ZnO nanomaterial for solar driven photocatalysis.

    Science.gov (United States)

    Namratha, K; Byrappa, K; Byrappa, S; Venkateswarlu, P; Rajasekhar, D; Deepthi, B K

    2015-08-01

    Hydrothermal fabrication of selectively doped (Ag(+)+Pd(3+)) advanced ZnO nanomaterial has been carried out under mild pressure temperature conditions (autogeneous; 150°C). Gluconic acid has been used as a surface modifier to effectively control the particle size and morphology of these ZnO nanoparticles. The experimental parameters were tuned to achieve optimum conditions for the synthesis of selectively doped ZnO nanomaterials with an experimental duration of 4 hr. These selectively doped ZnO nanoparticles were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and scanning electron microscopy (SEM). The solar driven photocatalytic studies have been carried out for organic dyes, i.e., Procion MX-5B dye, Cibacron Brilliant Yellow dye, Indigo Carmine dye, separately and all three mixed, by using gluconic acid modified selectively doped advanced ZnO nanomaterial. The influence of catalyst, its concentration and initial dye concentration resulted in the photocatalytic efficiency of 89% under daylight.

  4. Band Gap Narrowing and Widening of ZnO Nanostructures and Doped Materials.

    Science.gov (United States)

    Kamarulzaman, Norlida; Kasim, Muhd Firdaus; Rusdi, Roshidah

    2015-12-01

    Band gap change in doped ZnO is an observed phenomenon that is very interesting from the fundamental point of view. This work is focused on the preparation of pure and single phase nanostructured ZnO and Cu as well as Mn-doped ZnO for the purpose of understanding the mechanisms of band gap narrowing in the materials. ZnO, Zn0.99Cu0.01O and Zn0.99Mn0.01O materials were prepared using a wet chemistry method, and X-ray diffraction (XRD) results showed that all samples were pure and single phase. UV-visible spectroscopy showed that materials in the nanostructured state exhibit band gap widening with respect to their micron state while for the doped compounds exhibited band gap narrowing both in the nano and micron states with respect to the pure ZnO materials. The degree of band gap change was dependent on the doped elements and crystallite size. X-ray photoelectron spectroscopy (XPS) revealed that there were shifts in the valence bands. From both UV-visible and XPS spectroscopy, it was found that the mechanism for band gap narrowing was due to the shifting of the valance band maximum and conduction band minimum of the materials. The mechanisms were different for different samples depending on the type of dopant and dimensional length scales of the crystallites.

  5. Synthesis and microstructural evolution of BiFeO{sub 3} ceramics modified with ZnO; Sintesis y evolucion microestructural de ceramicas de BiFeO{sub 3} modificadas con ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Bernandrdo, M. S.; Ardiel, T.; Villegas, M.

    2010-07-01

    BiFeO{sub 3} ceramic materials have received a great interest in the last years due to their potential application as multiferroic devices. However, the preparation of BiFeO{sub 3}-based bulk ceramics shows serious difficulties related to the presence of secondary phases and the densification process. These problems result in a high electrical conductivity which up to now limits the technological applications of BiFeO{sub 3}. However, it has been observed experimentally that the conductivity in these ceramics can be reduced by acting on their microstructure. In this framework, the present contribution is focused on the analysis of the microstructural changes promoted by superficial doping of the BiFeO{sub 3} ceramic particles with ZnO. The structural and microstructural characterization of the obtained materials reveals that the addition of ZnO results in a solutedrag effect. Due to this effect the dopant remains segregated at the grain boundaries so inhibiting the grain growth during sintering. (Author)

  6. A facile green antisolvent approach to Cu2+-doped ZnO nanocrystals with visible-light-responsive photoactivities.

    Science.gov (United States)

    Lu, Yi-Hsuan; Lin, Wei-Hao; Yang, Chao-Yao; Chiu, Yi-Hsuan; Pu, Ying-Chih; Lee, Min-Han; Tseng, Yuan-Chieh; Hsu, Yung-Jung

    2014-08-07

    An environmentally benign antisolvent method has been developed to prepare Cu(2+)-doped ZnO nanocrystals with controllable dopant concentrations. A room temperature ionic liquid, known as a deep eutectic solvent (DES), was used as the solvent to dissolve ZnO powders. Upon the introduction of the ZnO-containing DES into a bad solvent which shows no solvation to ZnO, ZnO was precipitated and grown due to the dramatic decrease of solubility. By adding Cu(2+) ions to the bad solvent, the growth of ZnO from the antisolvent process was accompanied by Cu(2+) introduction, resulting in the formation of Cu(2+)-doped ZnO nanocrystals. The as-prepared Cu(2+)-doped ZnO showed an additional absorption band in the visible range (400-800 nm), which conduced to an improvement in the overall photon harvesting efficiency. Time-resolved photoluminescence spectra, together with the photovoltage information, suggested that the doped Cu(2+) may otherwise trap photoexcited electrons during the charge transfer process, inevitably depressing the photoconversion efficiency. The photoactivity of Cu(2+)-doped ZnO nanocrystals for photoelectrochemical water oxidation was effectively enhanced in the visible region, which achieved the highest at 2.0 at% of Cu(2+). A further increase in the Cu(2+) concentration however led to a decrease in the photocatalytic performance, which was ascribed to the significant carrier trapping caused by the increased states given by excessive Cu(2+). The photocurrent action spectra illustrated that the enhanced photoactivity of the Cu(2+)-doped ZnO nanocrystals was mainly due to the improved visible photon harvesting achieved by Cu(2+) doping. These results may facilitate the use of transition metal ion-doped ZnO in other photoconversion applications, such as ZnO based dye-sensitized solar cells and magnetism-assisted photocatalytic systems.

  7. Ultrasonic-assisted degradation of phenazopyridine with a combination of Sm-doped ZnO nanoparticles and inorganic oxidants.

    Science.gov (United States)

    Eskandarloo, Hamed; Badiei, Alireza; Behnajady, Mohammad A; Ziarani, Ghodsi Mohammadi

    2016-01-01

    Pure and samarium doped ZnO nanoparticles were synthesized by a sonochemical method and characterized by TEM, SEM, EDX, XRD, Pl, and DRS techniques. The average crystallite size of pure and Sm-doped ZnO nanoparticles was about 20 nm. The sonocatalytic activity of pure and Sm-doped ZnO nanoparticles was considered toward degradation of phenazopyridine as a model organic contaminant. The Sm-doped ZnO nanoparticles with Sm concentration of 0.4 mol% indicated a higher sonocatalytic activity (59%) than the pure ZnO (51%) and other Sm-doped ZnO nanoparticles. It was believed that Sm(3+) ion with optimal concentration (0.4 mol%) can act as superficial trapping for electrons in the conduction band of ZnO and delayed the recombination of charge carriers. The influence of the nature and concentration of various oxidants, including periodate, hydrogen peroxide, peroxymonosulfate, and peroxydisulfate on the sonocatalytic activity of Sm-doped ZnO nanoparticles was studied. The influence of the oxidants concentration (0.2-1.4 g L(-1)) on the degradation rate was established by the 3D response surface and the 2D contour plots. The results demonstrated that the utilizing of oxidants in combination with Sm-doped ZnO resulting in rapid removal of contaminant, which can be referable to a dual role of oxidants; (i) scavenging the generated electrons in the conduction band of ZnO and (ii) creating highly reactive radical species under ultrasonic irradiation. It was found that the Sm-doped ZnO and periodate combination is the most efficient catalytic system under ultrasonic irradiation.

  8. Room temperature ferromagnetism of Ni, (Ni, Li), (Ni, N)-doped ZnO thin films

    Institute of Scientific and Technical Information of China (English)

    AU; ChakTong

    2010-01-01

    Ni-doped ZnO thin films (Ni concentration up to 10 mol%) were generated on Si (100) substrates by a sol-gel technique. The films showed wurtzite structure and no other phase was found. The chemical state of Ni was found to be bivalent by X-ray photoelectron spectroscopy. The results of magnetic measurements at room temperature indicated that the films were ferromagnetic, and magnetic moment decreased with rise of Ni concentration. The magnetization of Ni (10 mol%)-doped ZnO film annealed in nitrogen was lower than that annealed in argon, suggesting that the density of defects had an effect on ferromagnetism.

  9. Preparation of Aligned ZnO Nanorod Arrays on Sn-Doped ZnO Thin Films by Sonicated Sol-Gel Immersion Fabricated for Dye-Sensitized Solar Cell

    OpenAIRE

    Saurdi, I.; Mamat, M. H.; M. F. Malek; M. Rusop

    2014-01-01

    Aligned ZnO Nanorod arrays are deposited on the Sn-doped ZnO thin film via sonicated sol-gel immersion method. The structural, optical, and electrical properties of the Sn-doped ZnO thin films were investigated. Results show that the Sn-doped ZnO thin films with small grain size (~20 nm), high average transmittance (96%) in visible region, and good resistivity 7.7 × 102 Ω·cm are obtained for 2 at.% Sn doping concentration. The aligned ZnO nanorod arrays with large surface area were also obtai...

  10. Photocatalytic degradation of toluene using sprayed N-doped ZnO thin films in aqueous suspension.

    Science.gov (United States)

    Shinde, S S; Bhosale, C H; Rajpure, K Y

    2012-08-01

    Thin films of N-doped ZnO are synthesized via spray pyrolysis technique in aqueous medium using zinc acetate and ammonium acetate as precursors. Influence of N doping onto photochemical, structural, morphological, optical and thermal properties have been investigated. Structural analysis depicts hexagonal (wurtzite) crystal structure. The effect of N doping on the photocatalytic activity of N-doped ZnO in the degradation of toluene is studied and results are compared with pure ZnO. The results show that the rate of degradation of toluene over N-doped ZnO is higher as compared to that of pure ZnO and increases with increasing N doping up to 10 at.% and then decreases. The enhancement of photocatalytic activity of N-doped ZnO thin films is mainly due to their capability for reducing the electron hole pair recombination. The photocatalytic mineralization of toluene in aqueous solution has been studied by measuring COD and TOC. Possible reaction mechanism pathways during toluene degradation over N-doped ZnO has been proposed.

  11. Synthesis of Na-doped ZnO hollow spheres with improved photocatalytic activity for hydrogen production.

    Science.gov (United States)

    Wu, Zhiwei; Li, Yaguang; Gao, Linjie; Wang, Shufang; Fu, Guangsheng

    2016-07-05

    The fabrication of p-type doped ZnO nanostructures is key in opening up substantial opportunities for the application of ZnO nanostructures. Owing to their stable p-type property, Na ions are the best candidates for ZnO p-type doping. However, Na-doped ZnO nanostructures had never been prepared until now. For the first time, we successfully synthesized Na-doped ZnO ultrathin hollow spheres using an ion adsorption and templating method. The obtained hollow spheres have ultrathin shells, uniform Na elemental distribution and a controllable concentration of doped Na. The energy position of the Fermi level decreased with continuously increasing Na doping concentration, revealing the p-type conductivity of Na-doped ZnO. We demonstrate that the photocatalytic hydrogen generation efficiency (with methanol) using ZnO ultrathin hollow spheres can be enhanced by more than 50 times after Na-doping and that the quantum efficiency can be as high as 13.5%.

  12. p Doping in Expanded Phases of ZnO: An Ab Initio Study

    Science.gov (United States)

    Hapiuk, D.; Marques, Miguel A. L.; Melinon, P.; Flores-Livas, José A.; Botti, Silvana; Masenelli, B.

    2012-03-01

    The issue of p doping in nanostructured cagelike ZnO is investigated by state-of-the-art calculations. Our study is focused on one prototypical structure, namely, sodalite, for which we show that p-type doping is possible for elements of the V, VI, and VII columns of the periodic table. However, some dopants tend to form dimers, thus impairing the stability of this kind of doping. This difference of behavior is discussed, and two criteria are proposed to ensure stable p doping.

  13. First-Principles Study on Magnetic Properties of V-Doped ZnO Nanotubes

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fu-Chun; ZHANG Zhi-Yong; ZHANG Wei-Hu; YAN Jun-Feng; YUN Jiang-Ni

    2009-01-01

    Electronic and magnetic properties of V-doped ZnO nanotubes in which one of Zn2+ ions is substituted by V2+ ions are studied by the first-principles calculations of plane wave ultra-soft pseudo-potential technology based on the spin-density function theory. The computational results reveal that spontaneous magnetization in V-doped (9,0) ZnO nanotubes can be induced without p-type or n-type doping treatment, and the ferromagnetism is isotropic and independent of the chirality and diameter of the nanotubes. It is found that V-doped ZnO nanotubes have large magnetic moments and are ferromagnetic half-metal materials. Moreover, the ferromagnetic coupling among V atoms is generated by O 2p electron spins and V 3d electron spins localized at the exchanging interactions between magnetic transitional metal (TM) impurities. The appearance of ferromagnetism in V-doped ZnO nanotubes gives some reference to fabrication of a transparent ferromagnet which may have a great impact on industrial applications in magneto-optical devices.

  14. Magneto-optical studies on doped and undoped ZnO nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Jankowski, Stephanie; Chen, Limei; Heimbrodt, Wolfram [Department of Physics and Material Science Center, Philipps-University Marburg, Renthof 5, D-35032 Marburg (Germany); Geburt, Sebastian; Ronning, Carsten [Physikalisch-Astronomische Fakultaet, Friedrich-Schiller-Universitaet Jena, Max-Wien-Platz 1, D-07743 Jena (Germany)

    2011-07-01

    High quality ZnO nanowires doped with different content of Manganese and Cobalt as well as ZnO quantum wells embedded between ZnMgO barriers are investigated by magneto photoluminescence and magnetic circular dichroism (MCD) in a split-coil superconducting magnet system. The measurements have been performed in magnetic fields up to 7 Tesla in a temperature range 1.6-300 K. MCD and Zeeman-spectroscopy in the excitonic region have been used to determine the g-factors of the samples. Even in case of transition metal doped ZnO surprisingly small Zeeman-splitting has been found. The reason for the rather small values as well as the change of sign of the g-value will be discussed. The transition metal doped ZnO shows also an interesting difference concerning the optical 3d intra-ionic transitions. Whereas in the Co-doped samples the 3d transitions are observable in case of the Mn-doped samples the Mn-PL is rather vanishing. The physical reasons for the odd behaviour will be discussed.

  15. Characterization of co-doped (In, N): ZnO by indigenous thermopower measurement system

    Science.gov (United States)

    Kedia, Sanjay Kumar; Singh, Anil; Chaudhary, Sujeet

    2016-05-01

    The thermopower measurement of (In, N) co-doped ZnO thin films have been carried out using indigenous high and low temperature thermopower measurement system. The compact thermopower measurement system has been designed, developed, tested in house. The sensitivity and accuracy of indigenous thermopower system have been investigated by measuring thermopower of standard samples like Cu, Ni, Sb etc. It has been also investigated by the comparison of carrier concentration using Hall Effect and Thermopower measurement of these (In, N) co-doped ZnO thin films. The constant temperature gradient between hot and cold junction has been maintained by using the temperature controller. The room temperature and low temperature Seebeck coefficient measurements were performed on these co-doped ZnO samples. A series of experiments have been performed to detect the p-type conductivity in co-doped ZnO thin films, particularly at low temperature. The negative Seebeck coefficient observed down to 40 K established the n-type behavior in these co-doped samples.

  16. Mg-doped ZnO nanoparticles for efficient sunlight-driven photocatalysis.

    Science.gov (United States)

    Etacheri, Vinodkumar; Roshan, Roshith; Kumar, Vishwanathan

    2012-05-01

    Magnesium-doped ZnO (ZMO) nanoparticles were synthesized through an oxalate coprecipitation method. Crystallization of ZMO upon thermal decomposition of the oxalate precursors was investigated using differential scanning calorimetry (DSC) and X-ray diffraction (XRD) techniques. XRD studies point toward a significant c-axis compression and reduced crystallite sizes for ZMO samples in contrast to undoped ZnO, which was further confirmed by HRSEM studies. X-ray photoelectron spectroscopy (XPS), UV/vis spectroscopy and photoluminescence (PL) spectroscopy were employed to establish the electronic and optical properties of these nanoparticles. (XPS) studies confirmed the substitution of Zn(2+) by Mg(2+), crystallization of MgO secondary phase, and increased Zn-O bond strengths in Mg-doped ZnO samples. Textural properties of these ZMO samples obtained at various calcination temperatures were superior in comparison to the undoped ZnO. In addition to this, ZMO samples exhibited a blue-shift in the near band edge photoluminescence (PL) emission, decrease of PL intensities and superior sunlight-induced photocatalytic decomposition of methylene blue in contrast to undoped ZnO. The most active photocatalyst 0.1-MgZnO obtained after calcination at 600 °C showed a 2-fold increase in photocatalytic activity compared to the undoped ZnO. Band gap widening, superior textural properties and efficient electron-hole separation were identified as the factors responsible for the enhanced sunlight-driven photocatalytic activities of Mg-doped ZnO nanoparticles.

  17. Characterization of Undoped and Cu-Doped ZnO Thin Films Deposited on Glass Substrates by Spray Pyrolysis

    Institute of Scientific and Technical Information of China (English)

    Metin Bedir; Mustafa (O)ztas; A. Necmeddin Yazici; E. Vural Kafadar

    2006-01-01

    @@ Undoped and copper doped zinc oxide (ZnO) thin films have been prepared on glass substrates by spray pyrolysis technique. The films were doped with copper using the direct method by addition of a copper salt (CuCl2) in the spray solution of ZnO. Variation of structural, electrical, optical and thermoluminescence (TL) properties with doping concentrations is investigated in detail.

  18. Synthesis and conductivity enhancement of Al-doped ZnO nanorod array thin films.

    Science.gov (United States)

    Hsu, Chih-Hsiung; Chen, Dong-Hwang

    2010-07-16

    Al-doped ZnO (AZO) nanorod array thin films with various Al/Zn molar ratios were synthesized by chemical bath deposition. The resultant AZO nanorods were well-aligned at the glass substrate, growing vertically along the c-axis [001] direction. In addition, they had an average diameter of 64.7 +/- 16.8 nm and an average length of about 1.0 microm with the structure of wurtzite-type ZnO. Analyses of energy dispersive x-ray spectra and x-ray photoelectron spectra indicated that Al atoms had been doped into the ZnO crystal lattice. The doping of Al atoms did not result in significant changes in the structure and crystal orientation, but the electrical resistivity was found to increase first and then decrease with increasing Al content owing to the increase of carrier concentration and the decrease of mobility. In addition, the transmission in the visible region increased but the increase was reduced at higher Al doping levels. After hydrogen treatment, the morphology of the AZO nanorod array thin films remained unchanged. However, the electrical resistivity decreased significantly due to the formation of oxygen vacancies and interstitial hydrogen atoms. When the real Al/Zn molar ratio was about 3.7%, the conductivity was enhanced about 1000 times and a minimum electrical resistivity of 6.4 x 10( - 4) Omega cm was obtained. In addition, the transmission of the ZnO nanorod array thin film in the visible region was significantly increased but the increase was less significant for the AZO nanorod array thin film, particularly at higher Al doping levels. In addition, the current-voltage curves of the thin film devices with ZnO or AZO nanorod arrays revealed that AZO had a higher current response than ZnO and hydrogen treatment led to a more significant enhancement of current responses (about 100-fold).

  19. ZIF-8 derived porous N-doped ZnO with enhanced visible light-driven photocatalytic activity

    Science.gov (United States)

    Feng, Yi; Lu, Haiqiang; Gu, Xiaoli; Qiu, Jianhao; Jia, Mingmin; Huang, Chaobo; Yao, Jianfeng

    2017-03-01

    A facile and simple method was offered to synthesize porous N-doped ZnO via direct calcination of urea and ZIF-8 mixture. From XRD and XPS analysis, nitrogen has been successfully incorporated into ZnO lattices without introducing other N-containing or Zn-containing phases. Such nitrogen doping can enhance the visible-light harvesting ability and inhibit the recombination rate of electron-hole pairs; as a result, improved visible-light driven photocatalytic activity was achieved in N-doped porous ZnO and the photocatalytic activity of N-doped ZnO is 2.58 times higher than that of ZIF-derived pure ZnO.

  20. Formation of Al-doped ZnO thin films on glass by sol-gel process and characterization

    Science.gov (United States)

    Shahid, M. U.; Deen, K. M.; Ahmad, A.; Akram, M. A.; Aslam, M.; Akhtar, W.

    2016-02-01

    In this study, pure ZnO and Al-doped ZnO thin films were developed on glass by sol-gel process followed by drying and annealing in air at 170 and 400 °C, respectively. The surface morphology and structural characteristics were determined through scanning electron microscopy, atomic force microscopy and X-ray diffraction. The Fourier transform infrared spectroscopy validated the formation of Al-doped ZnO film on glass substrate. It was evaluated that 1 at% aluminum (Al) doping in ZnO film showed low electrical resistivity and higher charge carrier concentration due to uniformly dispersed regular shape crystallites as compared to pure ZnO and 2 at% `Al'-doped thin films.

  1. Cl-doped ZnO nanowires with metallic conductivity and their application for high-performance photoelectrochemical electrodes.

    Science.gov (United States)

    Wang, Fei; Seo, Jung-Hun; Li, Zhaodong; Kvit, Alexander V; Ma, Zhenqiang; Wang, Xudong

    2014-01-22

    Doping semiconductor nanowires (NWs) for altering their electrical and optical properties is a critical strategy for tailoring the performance of nanodevices. ZnO NWs grown by hydrothermal method are pervasively used in optoelectronic, photovoltaic, and piezoelectric energy-harvesting devices. We synthesized in situ Cl-doped ZnO NWs with metallic conductivity that would fit seamlessly with these devices and improve their performance. Possible Cl doping mechanisms were discussed. UV-visible absorption spectroscopy confirmed the visible light transparency of Cl-doped ZnO NWs. Cl-doped ZnO NW/TiO2 core/shell-structured photoelectrochemical (PEC) anode was fabricated to demonstrate the application potential of highly conductive ZnO NWs. Higher photocurrent density and overall PEC efficiency compared with the undoped ZnO NW-based device were achieved. The successful doping and low resistivity of ZnO could unlock the potential of ZnO NWs for applications in low-cost flexible transparent electrodes.

  2. A comparative study of magnetic and optical properties of Mn-, Gd-, and Nd-doped ZnO nanowires

    Science.gov (United States)

    Chakraborty, Arup; Jong, Chol-Sam; Ganguli, Nirmal; Dasgupta, I.

    2017-01-01

    We present a comparative study of magnetism and optical properties for 3d transition metal (TM) (Mn)-doped and 4f rare-earth metals (Gd and Nd)-doped ultrathin ZnO nanowires using ab-initio density functional calculation. Our calculations indicate Nd-doped ZnO nanowires with oxygen vacancies are more favorable for ferromagnetism. Calculations including spin-orbit coupling for Nd-doped ZnO nanowires reveal not only giant anisotropy where magnetism parallel to the nanowire axis is found to be favorable but also stabilized ferromagnetism. We have calculated the absorption spectra for Mn-, Gd- and Nd-doped ZnO nanowires and found that the absorption intensity increases upon increasing the concentration of dopant ions. While Mn-doped ZnO nanowire allows absorption of light in the large energy window ranging from visible to ultraviolet, Gd- and Nd-doped systems absorb light primarily in the ultraviolet region. Our result indicates transition-metal-doped as well as rare-earth-doped ZnO nanowires may be ideal for spintronics and optoelectronic devices.

  3. Crystal and electronic structure study of Mn doped wurtzite ZnO nanoparticles

    Institute of Scientific and Technical Information of China (English)

    O.M. Ozkendir; S. Yildirimcan; A. Yuzer; K. Ocakoglu

    2016-01-01

    The change in the crystal and electronic structure properties of wurtzite ZnO nanoparticles was studied according to Mn doping in the powder samples. The investigations were conducted by X-ray Absorption Fine Structure Spectroscopy (XAFS) technique for the samples prepared with different heating and doping processes. Electronic analysis was carried out by the collected data from the X-ray Absorption Near-Edge Structure Spectroscopy (XANES) measurements. Additional crystal structure properties were studied by Extended-XAFS (EXAFS) analysis. Longer heating periods for the undoped wurtzite ZnO samples were determined to own stable crystal geometries. However, for some doped samples, the distortions in the crystal were observed as a result of the low doping amounts of Mn which was treated as an impurity. Besides, the changes in oxygen locations were determined to create defects and distor-tions in the samples.

  4. Crystal and electronic structure study of Mn doped wurtzite ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    O.M. Ozkendir

    2016-08-01

    Full Text Available The change in the crystal and electronic structure properties of wurtzite ZnO nanoparticles was studied according to Mn doping in the powder samples. The investigations were conducted by X-ray Absorption Fine Structure Spectroscopy (XAFS technique for the samples prepared with different heating and doping processes. Electronic analysis was carried out by the collected data from the X-ray Absorption Near-Edge Structure Spectroscopy (XANES measurements. Additional crystal structure properties were studied by Extended-XAFS (EXAFS analysis. Longer heating periods for the undoped wurtzite ZnO samples were determined to own stable crystal geometries. However, for some doped samples, the distortions in the crystal were observed as a result of the low doping amounts of Mn which was treated as an impurity. Besides, the changes in oxygen locations were determined to create defects and distortions in the samples.

  5. Microstructure and optical properties of nitrogen-doped ZnO film

    Institute of Scientific and Technical Information of China (English)

    Zhao Xian-Wei; Gao Xiao-Yong; Chen Xian-Mei; Chen Chao; Zhao Meng-Ke

    2013-01-01

    The nitrogen doping of ZnO film deposited by the magnetron sputtering method is subsequently realized by the hydrothermal synthesis method.The nitrogen-doped ZnO film is preferably (002) oriented.With the increase of hexamethylenetetramine (HMT) solution concentration,the average grain size of the film along the 〈002〉 direction almost immediately decreases and then monotonously increases,conversely,the lattice strain first increases and then decreases.The structural evolution of the film surface from compact and even to sparse and rough is attributed to the enhanced nitrogen doping content in the hydrothermal process.The transmission and photoluminescence properties of the film are closely related to grain size,lattice strain,and nitrogen-related defect arising from the enhanced nitrogen doping content with HMT concentration increasing.

  6. First-principles study on electronic and magnetic properties of N mono-doped and (N, Co) co-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Abbad, A., E-mail: am.ben@voila.fr [Laboratory of Material Valorisation, Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Bentounes, H.A. [Signals and Systems Laboratory (LSS), Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Benstaali, W. [Laboratory of Material Valorisation, Faculty of Sciences and Technology, BP 227, Abdelhamid Ibn Badis University, Mostaganem 27000 (Algeria); Belaidi, A. [Automatic and Systems Analysis Laboratory (LAAS), ENSET, Oran 31000 (Algeria)

    2013-01-15

    Using first principles calculations based on the density functional theory and local spin density approximation, we predict magnetic and electronic properties of N mono-doped and (N-Co) co-doped ZnO for different dopants concentration. The results show that ZnO doped with N concentration of 12.5% is p-type, semi-metallic and ferromagnetic due to the strong hybridization effect between N 2p and O 2p states, with a total magnetic moment of 1 {mu}{sub B} mainly arises from N 2p orbitals. Nevertheless we find a deep and narrow acceptor level, resulting in large acceptor ionization energy of ZnO (N). With increasing N concentration to 25% we find that the impurity energy level is shallow and shifts downward to the direction of low energy, consequentially, the acceptor binding energy is reduced. (N-Co) co-doped ZnO with a concentration of 12.5% for the two dopants is p-type and half-metallic with an important magnetic moment of 3.98 {mu}{sub B}, due to Co 3d and N 2p states. - Highlights: Black-Right-Pointing-Pointer The electronic and magnetic properties of N mono-doped and (N-Co) co-doped ZnO have been investigated. Black-Right-Pointing-Pointer ZnO doped with 12.5% of Nitrogen is p-type and semi-metallic. Black-Right-Pointing-Pointer N-doping can enhance electronic conductivity of N-doped ZnO. Black-Right-Pointing-Pointer We find narrow N-impurity band for N-doped ZnO. Black-Right-Pointing-Pointer The co-doping of Co donors with N-acceptors causes an important change from semi-metallic material to half-metallic one.

  7. Gd doping effect on structural, electrical and magnetic properties of ZnO thin films synthesized by sol-gel spin coating technique

    Science.gov (United States)

    Kumar, Sanjeev; Thangavel, Rajalingam

    2017-03-01

    Nanocrystalline Gd-doped ZnO thin films were deposited on sapphire (0001) substrates using sol-gel spin coating technique. The structural and optical properties of deposited thin films were characterized by X-ray diffraction (XRD) and micro Raman spectroscopy. Structural and optical studies show that the doped Gd ions occupy Zn sites retaining the wurtzite symmetry. Photoluminescence (PL) studies reveal the presence of oxygen vacancies in Gd doped ZnO thin films. The resistivity of Gd doped ZnO thin film decreases with increase in Gd doping upto 4%. Gd-doped ZnO films demonstrate weak magnetic ordering at room temperature.

  8. Optical properties of Mn doped ZnO films and wires synthesized by thermal oxidation of ZnMn alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sima, M., E-mail: msima@infim.ro [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Mihut, L. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania); Vasile, E. [University “Politehnica”of Bucharest, Faculty of Applied Chemistry and Material Science, Department of Oxide Materials and Nanomaterials, No. 1-7 Gh. Polizu Street, 011061 Bucharest (Romania); Sima, Ma.; Logofatu, C. [National Institute of Materials Physics, 105bis Atomistilor Street, 077125 Magurele (Romania)

    2015-09-01

    Mn doped ZnO films and wires, having different manganese concentrations were synthesized by thermal oxidation of the corresponding ZnMn alloy films and wires electrodeposited on a gold substrate. Structural and optical properties were addressed with scanning electron microscopy, X-ray diffraction (XRD), Raman scattering and photoluminescence (PL). To estimate the manganese concentration in Mn doped ZnO films, X-ray photoelectron spectroscopy was used. XRD patterns indicate that the incorporation of Mn{sup 2+} ions into the Zn{sup 2+} site of ZnO lattice takes place. Quenching of the ZnO PL appears due to Mn{sup 2+} ions in the ZnO lattice. Moreover, a significant decrease in the green emission of ZnO is reported in the case of the Mn doped ZnO wire array with a Mn concentration of 1.45%. The wurtzite ZnO has a total of 12 phonon modes, namely, one longitudinal acoustic (LA), two transverse acoustic (TA), three longitudinal optical (LO), and six transverse optical branches. Compared to the undoped ZnO, a gradual up-shift of the Raman lines assigned to the 2LA and A{sub 1} (LO) vibrational modes, from 482 and 567 cm{sup −1} to 532 and 580 cm{sup −1}, respectively, takes place for the Mn doped ZnO films having a Mn concentration between 2 and 15%. Additionally, in the case of the Mn doped ZnO films with 7 and 15% Mn concentration, Raman spectra show the appearance and increase in the relative intensity of the ZnO Raman line assigned to the TA + LO vibrational mode in the 600–750 cm{sup −1} spectral range. For the Mn-doped ZnO wires, the presence of the Raman line peaking at 527 cm{sup −1} confirms the insertion of Mn{sup 2+} ions in ZnO lattice. - Highlights: • Mn doped ZnO films and wires grown by thermal oxidation of ZnMn alloy • Incorporation of Mn{sup 2+} ions into Zn{sup 2+} site of ZnO lattice • Appearance of a strong Raman line in the spectral range 600–800 cm{sup −1} at high Mn concentration • Compensation of the oxygen vacancy at higher

  9. Stress-dependent band gap shift and quenching of defects in Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Bhupendra K; Khare, Neeraj, E-mail: nkhare@physics.iitd.ernet.i [Department of Physics, IIT Delhi, New Dehi-110016 (India)

    2010-11-24

    Al-doped ZnO (AZO) films were deposited on quartz substrates by the ultrasonically assisted chemical vapour deposition technique. The undoped ZnO film was found to be subjected to a stress which increases initially up to 3% Al doping, and then a slight decrease was observed for 5% Al doping. The band gap of AZO shows a blue shift up to 3% of Al doping as compared with the undoped ZnO. The blue shift in the band gap of the AZO films cannot be understood in the framework of Burstein-Moss shift and has been attributed to an increase in the stress present in the film. The photoluminescence spectrum of the undoped ZnO film shows a wide peak in the visible region which is suppressed with a small red shift after Al doping in the ZnO film. A detailed analysis of photoluminescence of ZnO and AZO films indicates suppression of zinc interstitials (Zn{sub i}) and oxygen vacancies (V{sub O}) and creation of oxygen interstitial (O{sub i}) defects after Al doping in ZnO films. X-ray photoelectron spectroscopy study also reveals suppression of oxygen vacancy related defects after Al doping in the ZnO film. The presence of Al in the ZnO matrix seems to change the defect equilibria leading to a suppression of Zn{sub i} and V{sub O} and enhancement of O{sub i} defects. The suppression of Zn{sub i} defects is correlated with the increase in stress in Al-doped ZnO films.

  10. Room-temperature ferromagnetism in Co-doped ZnO thin films prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Belghazi, Y. [Laboratoire de Physique des Materiaux, Faculte des Sciences, B.P. 1014, Rabat (Morocco); IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Schmerber, G. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Colis, S. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Rehspringer, J.L. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Berrada, A. [Laboratoire de Physique des Materiaux, Faculte des Sciences, B.P. 1014, Rabat (Morocco); Dinia, A. [IPCMS-GMI (UMR 7504 du CNRS) (ECPM-ULP), 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France)]. E-mail: aziz.dinia@ipcms.u-strasbg.fr

    2007-03-15

    We report on room-temperature ferromagnetism in Co-doped ZnO thin films grown onto Si(100) and SiO{sub 2} substrates using the spin-coating technique. X-ray diffraction measurements show that the films have the wurtzite structure with a preferential orientation along the c-axis. UV-Visible spectroscopy has shown that the Co{sup 2+} ions are substituted to Zn{sup 2+} ions in ZnO matrix. The analysis of the magnetization measurements indicates that the observed ferromagnetism in ZnO and Co-doped ZnO films is extrinsic and can be due to a pollution.

  11. LiFePO_4/C via fluoride doping

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Non-stoichiometric compound fluoride-doped LiFePO4/C cathode materials were synthesized via solid-state reaction using MgF2 and AlF3 as dopant. The fluoride-doped LiFePO4/C samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical testing. The results show that the materials are well crystallized and fluoride doping cannot change the space structure of LiFePO4. Slight amounts of Fe2O3 with no fluoride impurity were ...

  12. Eradication of Multi-drug Resistant Bacteria by Ni Doped ZnO Nanorods: Structural, Raman and optical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Jan, Tariq [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University Islamabad (Pakistan); Iqbal, Javed, E-mail: javed.saggu@iiu.edu.pk [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University Islamabad (Pakistan); Ismail, Muhammad; Mansoor, Qaisar [Institute of Biomedical and Genetic Engineering (IBGE), Islamabad (Pakistan); Mahmood, Arshad [Nano Devices Labs, National Institute of Lasers and Optronics (NILOP), Islamabad (Pakistan); Ahmad, Amaar [Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University Islamabad (Pakistan)

    2014-07-01

    In this paper, ZnO nanorods doped with varying amounts of Ni have been prepared by chemical co-precipitation technique. Structural investigations provide the evidence that Ni is successfully doped into ZnO host matrix without having any secondary phases. Scanning electron microscopy (SEM) images reveal the formation of rodlike structure of undoped ZnO with average length and diameter of 1 μm and 80 nm, respectively. Raman spectroscopy results show that the E{sub 1}{sup LO} phonons mode band shifts to the higher values with Ni doping, which is attributed to large amount of crystal defects. Ni doping is also found to greatly influence the optical properties of ZnO nanorods. The influence of Ni doping on antibacterial characteristics of ZnO nanorods have been studied by measuring the growth curves of Escherichia coli (E. coli), Methicillin-resistant Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) bacteria in the presence of prepared nanorods. ZnO nanorods antibacterial potency is found to increase remarkably with Ni doping against S. aureus and P. aeruginosa microbials, which might possibly be due to the increase in reactive oxygen species (ROS) generation. Interestingly, it is observed that Ni doped ZnO nanorods completely eradicates these multi-drug resistant bacteria.

  13. Preparation and characterization of sol-gel Al-doped ZnO thin films and ZnO nanowire arrays grown on Al-doped ZnO seed layer by hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jin; Que, Wenxiu [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an, Jiaotong University, Xi' an 710049, Shaanxi (China)

    2010-12-15

    Al-doped ZnO (AZO) nanocrystalline thin films are prepared by a sol-gel technique. Effects of the Al-doped concentration on microstructural, electrical and optical properties of the AZO thin films are studied and discussed. Results indicate that the AZO crystalline thin film with a highly preferred c-axis orientation perpendicular to the substrate is grown, and the AZO thin film with a small crystal grain size of 30-40 nm, high transmittance of above 90% in visible region, and low resistivity of 1.9 x 10{sup -2} {omega} cm can be obtained when the Al-doped concentration is up to 1 at%. Furthermore, ZnO nanowire (ZnO NW) arrays with a large surface area are grown on the sol-gel derived AZO thin film, which acts as a seed layer, by using a hydrothermal method. Optical properties of the grown ZnO NW arrays reveal that a high transmittance in visible region can be obtained, and only a strong UV emission at about 380 nm is observed in the room-temperature photoluminescence spectra, which implies that few crystal defects exist inside the as-assembled ZnO NW arrays. (author)

  14. Hydrothermal growth and properties of rod-like ZnO submicron crystals on Al-doped ZnO seed layers with different Al concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Yeob; Kim, Sung O [Clemson University, Clemson, South Carolina (United States); Kim, Min Su; Yim, Kwang Gug; Leem, Jae Young; Kim, Soa Ram; Nam, Gi Woong [Inje University, Gimhae (Korea, Republic of); Lee, Dong Yul [Samsung LED Co. Ltd., Suwon (Korea, Republic of)

    2012-01-15

    The authors used a sol-gel method to deposit Al-doped ZnO (AZO) thin films on Si substrates and a hydrothermal method to grow ZnO crystals on the as-prepared AZO seed layers. Though the crystallinity of the seed layers was enhanced by Al doping, for Al doping up to 3 at.%, the full width at half maximum (FWHM) of the ZnO (002) diffraction peak increased, resulting in a decrease in the average grain size. The intensity of the ZnO (002) diffraction peak of ZnO crystals grown on AZO seed layers increased as the Al doping concentration was increased to 1.0 at.%. The narrowest FWHM in the photoluminescence spectrum, 132 meV was obtained at an Al doping concentration of 1.0 at.%. These results indicate that the structural and the optical properties of ZnO crystals grown on seed layers can be enhanced by introducing a small amount of an Al dopant into the seed layers.

  15. Enhanced photovoltaic performance of ZnO nanorod-based dye-sensitized solar cells by using Ga doped ZnO seed layer

    Energy Technology Data Exchange (ETDEWEB)

    Dou, Yuanyao [State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044 (China); Department of Applied Physics, College of Physics, Chongqing University, Chongqing 401331 (China); Wu, Fang, E-mail: fang01234@163.com [State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044 (China); Department of Applied Physics, College of Physics, Chongqing University, Chongqing 401331 (China); Mao, Caiying [Department of Applied Physics, College of Physics, Chongqing University, Chongqing 401331 (China); Fang, Liang, E-mail: lfang@cqu.edu.cn [State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044 (China); Department of Applied Physics, College of Physics, Chongqing University, Chongqing 401331 (China); Guo, Shengchun [Department of Applied Physics, College of Physics, Chongqing University, Chongqing 401331 (China); Zhou, Miao [State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044 (China)

    2015-06-05

    Highlights: • ZnO nanorods were grown on Ga-doped ZnO seed layers using hydrothermal method. • Using the ZnO nanorods as photoanodes for fabricated dye-sensitized solar cells. • The highest η of 1.23% can be achieved in a DSSC with 3 at.% Ga-doped in seeds. • The effects of ZnO seed layers on electron transport properties were investigated. • The enhancement performance of DSSCs contributed to higher dye loading and η{sub cc}. - Abstract: Zinc oxide (ZnO) nanorod arrays were grown on FTO substrates with a Ga-doped ZnO (GZO) seed layer by a hydrothermal method. GZO seed layers were obtained via sol–gel technology with Ga concentration in the range of 0–4 at.%. The dye sensitized solar cells (DSSCs) using ZnO nanorod arrays as the photoanode layers were prepared. The effect of Ga dopant concentrations in ZnO seed layer on the morphology features of ZnO nanorod arrays and the performance of DSSCs were systematically investigated. Results indicate that the average diameter and density of ZnO nanorod arrays decrease with increasing Ga concentration, but their length shows an opposite trend. The photocurrent density–voltage (J–V) characteristics reveal that the DSSCs with GZO seed layer exhibit significantly improved photovoltaic performance. In particular, the highest energy conversion efficiency (η) of 1.23% can be achieved in a DSSC with 3 at.% Ga doping, which is increased by 86.36% compared with that of the undoped DSSC. The external quantum efficiency (EQE) spectra and electrochemical impedance spectroscopy (EIS) were employed to explore the photon-to-electron conversion process in DSSCs. It is demonstrated that the performance enhancement of DSSCs based on GZO seed layer can be attributed to higher amount of dye loading, more efficient electron transportation and better electrons collection efficiency.

  16. Li and Ag Co-Doped ZnO Photocatalyst for Degradation of RO 4 Dye Under Solar Light Irradiation.

    Science.gov (United States)

    Dhatshanamurthi, P; Shanthi, M

    2016-06-01

    The synthesis of Li doped Ag-ZnO (Li-Ag-ZnO) has been successfully achieved by a sonochemically assisted precipitation-decomposition method. The synthesized catalyst was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), X-ray photoelectron spectra (XPS) and BET surface area measurements. The photocatalytic activity of Li-Ag-ZnO was investigated for the degradation of Reactive orange 4 (RO 4) dye in aqueous solution under solar light irradiation. Co-dopants shift the absorbance of ZnO to the visible region. Li-Ag-ZnO is found to be more efficient than Ag-ZnO, Li-ZnO, commercial ZnO and prepared ZnO at pH 7 for the mineralization of RO 4 dye under solar light irradiation. The influences of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo-mineralization of RO 4 have been analyzed. The mineralization of RO 4 dye has been confirmed by COD measurements. A degradation mechanism is proposed for the degradation of RO 4 under solar light. The catalyst was found to be more stable and reusable.

  17. Optoelectronics and formaldehyde sensing properties of tin-doped ZnO thin films

    Science.gov (United States)

    Prajapati, C. S.; Kushwaha, Ajay; Sahay, P. P.

    2013-11-01

    Sn-doped ZnO thin films were deposited on clean glass substrates using the chemical spray pyrolysis technique. XRD analyses confirm stable ZnO hexagonal wurtzite structure of the films with crystallite size in the range of 20-28 nm. The surface roughness of the films increases on Sn doping, which favors to higher adsorption of oxygen species on the film surface, resulting in higher gas response. Optical studies reveal that the band gap decreases on Sn doping. All the films show near band edge emission, and on Sn doping the luminescence peak intensity has been found to increase. Photocurrent in the 1.5 at.% doped film enhances about three times to that observed in the undoped ZnO film. Among all the films examined, the 1.5 at.% Sn-doped film exhibits the maximum response (˜94.5 %) at the operating temperature of 275 °C for 100 ppm concentration of formaldehyde, which is much higher than the response (˜35 %) in the undoped film. The gas response of the film is attributed to the chemisorption of oxygen on the film surface and the subsequent reaction between the adsorbed oxygen species and the formaldehyde molecules.

  18. Preparation of manganese-doped ZnO thin films and their characterization

    Indian Academy of Sciences (India)

    S Mondal; S R Bhattacharyya; P Mitra

    2013-04-01

    In this study, pure and manganese-doped zinc oxide (Mn:ZnO) thin films were deposited on quartz substrate following successive ion layer adsorption and reaction (SILAR) technique. The film growth rate was found to increase linearly with number of dipping cycle. Characterization techniques of XRD, SEM with EDX and UV–visible spectra measurement were done to investigate the effect of Mn doping on the structural and optical properties of Mn:ZnO thin films. Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing manganese incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing manganese impurification. The average particle size for pure ZnO is 29.71nm and it reduces to 23.76nm for 5%Mn-doped ZnO. The strong preferred c-axis orientation is lost due to manganese (Mn) doping. The degree of polycrystallinity increases and the average microstrain in the films decreases with increasing Mn incorporation. Incorporation of Mn was confirmed from elemental analysis using EDX. As the Mn doping concentration increases the optical bandgap of the films decreases for the range of Mn doping reported here. The value of fundamental absorption edge is 3.22 eV for pure ZnO and it decreases to 3.06 eV for 5%Mn:ZnO.

  19. Enhanced photoelectrochemical and optical performance of ZnO films tuned by Cr doping

    Science.gov (United States)

    Salem, M.; Akir, S.; Massoudi, I.; Litaiem, Y.; Gaidi, M.; Khirouni, K.

    2017-04-01

    In this paper, pure and Cr-doped nanostructured Zinc oxide thin films were synthesized by simple and low cost co-precipitation and spin-coating method with Cr concentration varying between 0.5 and 5 at.%. Crystalline structure of the prepared films was investigated by X-ray diffraction (XRD) and Raman spectroscopy techniques. XRD analysis indicated that the films were indexed as the hexagonal phase of wurtzite-type structure and demonstrated a decrease in the crystallite size with increasing Cr doping content. Cr doping revealed a significant effect on the optical measurements such as transmission and photoluminescence properties. The optical measurements indicated that Cr doping decreases the optical band gap and it has been shifted from 3.41 eV for pure ZnO film to 3.31 eV for 5 at.% Cr-doped one. The photoelectrochemical (PEC) sensing characteristics of Cr-doped ZnO layers were investigated. Amongst all photo-anodes with different Cr dopant concentration, the 2 at.% Cr incorporated ZnO films exhibited fast response and higher photoconduction sensitivity.

  20. Electronic structure and optical properties of Al-doped ZnO.

    Science.gov (United States)

    Qu, Xiurong; Lü, Shuchen; Jia, Dechang; Fu, Shufang

    2011-11-01

    Impure ZnO materials are of great interest in optic and electronic applications. In this work, the effects of Al-doping on the electronic structures of ZnO system are investigated in detail. We find that the crystal structure strains significantly due to the introduction of Al impurity. On the other hand, the electronic band structures show that the position of the Fermi level moves upwards and the bands split near the band gap due to the introduction of Al. This is attributed to the interaction between Al3p and Zn4s orbital, which tend to drive the system towards semimetal. Photoluminescence (PL) studies indicate that the Al-doped ZnO samples have a high density of defects. This can be explained qualitatively by the above analysis on electronic structure.

  1. Influence of Bi doping on the electrical and optical properties of ZnO thin films

    Science.gov (United States)

    Abed, S.; Bougharraf, H.; Bouchouit, K.; Sofiani, Z.; Derkowska-Zielinska, B.; Aida, M. S.; Sahraoui, B.

    2015-09-01

    Transparent conducting ZnO doped Bi thin films were prepared on glass substrates by ultrasonic spray method. The influence of Bi doping concentration on the structural, optical and nonlinear optical properties of ZnO thin films was studied. The X-ray diffraction (XRD) analysis show that all studied films have a hexagonal wurtzite structure and are preferentially oriented along the c-axis from substrate surface. Optical transmittance measurements show that all samples have average 80% transparency in the visible light. Optical band gap values range between 3.14 and 3.28 eV. ZnO film with 3 wt% of Bi showed the highest electrical conductivity. In addition, the second and third order nonlinear susceptibilities were determined and their values have been calculated.

  2. Tunable surface plasmon resonance and enhanced electrical conductivity of In doped ZnO colloidal nanocrystals

    Science.gov (United States)

    Ghosh, Sirshendu; Saha, Manas; de, S. K.

    2014-05-01

    We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The dopant induced shape evolution changes the hexagonal pyramid structured ZnO to a platelet like structure upon 8% In doping. The introduction of trivalent In3+ into the ZnO lattice and consequent substitution of divalent Zn2+ generates free electrons in the conduction band which produces a plasmonic resonance in the infrared region. The electron concentration controls plasmon frequency as well as the band gap of host ZnO. The variation of the band gap and the modification of the conduction band have been explained by the Burstein-Moss effect and Mie's theory respectively. The In dopant changes the defect chemistry of pure ZnO nanocrystals which has been studied by photoluminescence and other spectroscopic measurements. The nanocrystals are highly stable in the organic medium and can be deposited as a crack free thin film on different substrates. Careful ligand exchange and thermal annealing of the spin cast film lead to a good conductive film (720 Ω per square to 120 Ω per square) with stable inherent plasmonic absorption in the infrared and 90% transmittance in the visible region. A temperature induced metal-semiconductor transition was found for doped ZnO nanocrystals. The transition temperature shifts to a lower temperature with increase of the doping concentration.We report a new synthesis process of colloidal indium (In) doped zinc oxide (ZIO) nanocrystals by a hot injection technique. By fine tuning the synthesis we reached the same nucleation temperature for indium oxide and zinc oxide which helped us to study a dopant precursor dependent In incorporation into the ZnO matrix by using different In sources. The

  3. Raman Spectroscopy and Magnetic Properties of Mn-Doped ZnO Bulk Single Crystal

    Institute of Scientific and Technical Information of China (English)

    HE Qing-Bo; XU Jia-Yue; LI Xin-Hua; A.Kamzin; L.Kamzina

    2007-01-01

    Mn doped ZnO bulk single crystals are grown by the modified Bridgman method.The as-grown crystals are red in colour.The additional Raman mode observed at 524 cm-1 is attributed to the Mn ions incorporating into ZnO crystal.The crystal exhibited paramagnetic under lower applied fleld below 2280 Oe.Then diamagnetism is observed in the crystal when the magnetic field rises up and becomes dorainant under applied field above 5270 Oe.The magnetic susceptibility dependence on the temperature follows a Curie law indicating a typical paramagnetic characteristic under an applied field of 2kOe.No ferromagnetic ordering is observed in the as-grown Mn-doped ZnO crystal.

  4. Surface morphology and photoluminescence studies of Sb-doped ZnO layers grown using MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Sartel, Corinne; Haneche, Nadia; Jomard, Francois; Lusson, Alain; Vilar, Christele; Laroche, Jean-Michel; Galtier, Pierre; Sallet, Vincent [Groupe d' Etude de la Matiere Condensee (GEMaC), CNRS-Universite de Versailles Saint Quentin, Meudon (France)

    2010-07-15

    ZnO and ZnO:Sb films were deposited using low pressure metal organic chemical vapor deposition on C- and R-oriented sapphire and O-polar ZnO substrates. Surface morphologies were studied using scanning electron microscopy. Whereas ZnO films grown on C-sapphire show a rough surface and hexagonal rods, the doped ZnO:Sb layers exhibit a relatively smoother surface, indicating a possible surfactant effect of antimony. The secondary ion mass spectrometry measurements permit to determine the antimony profile in the doped layers. Sb concentrations from 10{sup 18} to 10{sup 20} at/cm{sup 3} were measured, depending on the growth conditions and substrate nature. Photoluminescence spectra exhibit donor-acceptor pair emission at 3.22 eV. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  5. Enhanced luminescence in Eu-doped ZnO nanocrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Keigo, E-mail: ksuzuki@murata.com; Murayama, Koji; Tanaka, Nobuhiko [Murata Manufacturing Co., Ltd., 10-1, Higashikotari 1-chome, Nagaokakyo, Kyoto 617-8555 (Japan)

    2015-07-20

    We found an enhancement of Eu{sup 3+} emissions in Eu-doped ZnO nanocrystalline films fabricated by microemulsion method. The Eu{sup 3+} emission intensities were increased by reducing annealing temperatures from 633 K to 533 K. One possible explanation for this phenomenon is that the size reduction enhances the energy transfer from ZnO nanoparticles to Eu{sup 3+} ions. Also, the shift of the charge-transfer band into the low-energy side of the absorption edge is found to be crucial, which seems to expedite the energy transfer from O atoms to Eu{sup 3+} ions. These findings will be useful for the material design of Eu-doped ZnO phosphors.

  6. Structural and photoluminescence properties of Ce, Dy, Er-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Jayachandraiah, C. [Department of Physics, JNTU, Anantapur-515002 (India); Kumar, K. Siva [Department of Advanced Materials Science and Engineering, Dankook University, Cheonan, Chungnam 330-714 (Korea, Republic of); Krishnaiah, G., E-mail: ginnerik@gmail.com [Govt. Degree College, Puttur, Chittoor-517 583 (India)

    2015-06-24

    Undoped ZnO and rare earth elements (Ce, Dy and Er with 2 at. %) doped nanoparticles were synthesized by wet chemical co-precipitation method at 90°C with Polyvinylpyrrolidone (PVP) as capping agent. The structural, morphological, compositional and photoluminescence studies were performed with X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDS), FTIR spectroscopy and Photoluminescence (PL) respectively. XRD results revealed hexagonal wurtzite structure with average particle size around 18 nm - 14 nm and are compatible with TEM results. EDS confirm the incorporation of Ce, Dy and Er elements into the host ZnO matrix and is validated by FTIR analysis. PL studies showed a broad intensive emission peak at 558 nm in all the samples. The intensity for Er- doped ZnO found maximum with additional Er shoulder peaks at 516nm and 538 nm. No Ce, Dy emission centers were found in spectra.

  7. Study on Ni-doped ZnO films as gas sensors

    Science.gov (United States)

    Rambu, A. P.; Ursu, L.; Iftimie, N.; Nica, V.; Dobromir, M.; Iacomi, F.

    2013-09-01

    Ni doped ZnO films were obtained by spin coating, using zinc acetate and nickel acetate as starting materials and N,N-dimethylformamide as solvent. The X-ray diffraction (XRD) analysis indicates that, spin coated films posses a polycrystalline structure. Ni doped ZnO films are single phase and no trace of nickel metal or binary zinc nickel phases are observed. The values of some structural parameters (crystallite size, surface roughness) are varying with the variation of Ni concentration. The sensitivity of Ni:ZnO films, at three different gasses (ammonia, liquefied petroleum gas and ethanol) was investigated. Obtained results indicate that our films are most sensitive to ammonia, the operating temperature was found to be 190 °C and the response time is 35 s. The gas sensitivity was found to depend on the Ni concentration in ZnO films.

  8. Resistive switching characteristics of a compact ZnO nanorod array grown directly on an Al-doped ZnO substrate

    Science.gov (United States)

    Yoo, E. J.; Shin, J. Y.; Yoon, T. S.; Kang, C. J.; Choi, Y. J.

    2016-07-01

    ZnO’s resistive switching properties have drawn much attention because ZnO has a simple chemical composition and is easy to manipulate. The propulsion mechanism for resistive switching in ZnO is based on a conducting filament that consists of oxygen vacancies. In the case of film structure, the random formation of the conducting filaments occasionally leads to unstable switching characteristics. Limiting the direction in which the conducting filaments are formed is one way to solve this problem. In this study, we demonstrate reliable resistive switching behavior in a device with an Au/compact ZnO nanorod array/Al-doped ZnO structure with stable resistive switching over 105 cycles and a long retention time of 104 s by confining conducting filaments along the boundaries between ZnO nanorods. The restrictive formation of conducting filaments along the boundaries between ZnO nanorods is observed directly using conductive atomic force microscopy.

  9. Electronic Structure and Magnetism of Mn-Doped ZnO Nanowires

    Science.gov (United States)

    Zhang, Fuchun; Chao, Dandan; Cui, Hongwei; Zhang, Weihu; Zhang, Weibin

    2015-01-01

    The geometric structures, electronic and magnetic properties of Mn-doped ZnO nanowires were investigated using density functional theory. The results indicated that all the calculated energy differences were negative, and the energy of the ground state was 0.229 eV lower than ferromagnetic coupling, which show higher stability in antiferromagnetic coupling. The calculated results indicated that obvious spin splitting phenomenon occurred near the Femi level. The Zn atoms on the inner layer of ZnO nanowires are easily substituted by Mn atoms along the [0001] direction. It was also shown that the Mn2+-O2−-Mn2+ magnetic coupling formed by intermediate O atom was proved to be caused by orbital hybridization between Mn 3d and O 2p states. The magnetic moments were mainly attributed to the unpaired Mn 3d orbitals, but not relevant with doping position of Mn atoms. Moreover, the optical properties of Mn-doped ZnO nanowires exhibited a novel blue-shifted optical absorption and enhanced ultraviolet-light emission. The above results show that the Mn-doped ZnO nanowires are a new type of magneto-optical materials with great promise.

  10. Structural, spectroscopic and magnetic characterization of undoped, Ni{sup 2+} doped ZnO nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Babu, B.; Sundari, G. Rama; Ravindranadh, K.; Yadav, M. Rajesh; Ravikumar, R.V.S.S.N., E-mail: rvssn@yahoo.co.in

    2014-12-15

    Structural, magnetic and optical properties of undoped and Ni{sup 2+} doped ZnO nanopowders have been prepared by sonochemical assistance. Powder XRD studies confirm the hexagonal structure of both undoped and Ni{sup 2+} doped of ZnO nanopowders and its average crystallite sizes are evaluated. Optical absorption and Electron Paramagnetic Resonance spectral data confirmed the site symmetry for Ni{sup 2+} ions as octahedral. Photoluminescence spectra exhibited the emission bands in ultraviolet and blue regions at an excitation wavelength of 328 nm. FT-IR spectra showed the characteristic vibrational bands of Zn–O. Vibrating sample magnetometer was used for the magnetic property investigations and indicates room temperature ferromagnetism which is intrinsic in nature and attributed to oxygen and/or Zn deficiencies. - Highlights: • Undoped and Ni{sup 2+} doped ZnO nanopowders were synthesized by sonochemical assistance. • PL spectra exhibited violet and blue emissions which shows good optical properties. • From optical and EPR studies, site symmetry of dopant is octahedral in host lattice. • Room temperature ferromagnetism is observed in both undoped and Ni-doped ZnO.

  11. Doping effect on the optical properties of ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Stoehr, M. [Frederick Seitz Materials Research Laboratory, University of Illinois,104 South Goodwin Avenue, Urbana, IL 61801 (United States); Institut Universitaire de Technologie, Universite de Haute Alsace, 61 rue Albert Camus, 68093 Mulhouse Cedex (France); Juillaguet, S. [Groupe d' Etude des Semi-conducteurs, Universite Montpellier II, Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Kyaw, T.M.; Wen, J.G. [Institut Universitaire de Technologie, Universite de Haute Alsace, 61 rue Albert Camus, 68093 Mulhouse Cedex (France)

    2007-04-15

    High quality undoped and Ga{sub 2}O{sub 3} or In{sub 2}O{sub 3} doped ZnO nanostructures are grown by chemical vapor transport and condensation. The doping effect on the optical properties is investigated by photoluminescence. At room temperature, photoluminescence on Ga{sub 2}O{sub 3} doped ZnO nanostructures reveals an enhancement of the ultraviolet near band edge emission at 390 nm, while the intensity of the deep level emission at 530 nm weakens. At 5 K, an intense neutral-donor-bound exciton (D{sup 0}X) line dominates the undoped and doped ZnO photoluminescence spectra. The presence of well resolved two-electron satellite lines allow to determine the type of donors. At 5 K, the results indicate that ZnO nanostructures grown with 10% of Ga{sub 2}O{sub 3} display an excellent optical quality, proved by an intense D{sup 0}X line, a high intensity ratio between the D{sup 0}X line and the deep level emission as well as the presence of numerous phonon replicas of the main lines. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Pulsed laser deposition of aluminum-doped ZnO films at 355 nm

    DEFF Research Database (Denmark)

    Holmelund, E.; Schou, Jørgen; Thestrup Nielsen, Birgitte;

    2004-01-01

    Conducting, transparent films of aluminium-doped ZnO (AZO) have been produced at the laser wavelength 355 nm. The most critical property, the electric resistivity, is up to a factor of 8 above that for films produced at shorter wavelengths. In contrast, the transmission of visible light through...

  13. Structural and electrical properties of atomic layer deposited Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Do-Joong; Kim, Hyun-Mi; Kwon, Jang-Yeon; Choi, Hyoji [Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); Kim, Soo-Hyun [School of Materials Science and Engineering, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 712-749 (Korea, Republic of); Kim, Ki-Bum [Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of); WCU Hybrid Materials Program, Department of Materials Science and Engineering, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-742 (Korea, Republic of)

    2011-02-08

    Structural and electrical properties of Al-doped ZnO (AZO) films deposited by atomic layer deposition (ALD) are investigated to study the extrinsic doping mechanism of a transparent conducting oxide. ALD-AZO films exhibit a unique layer-by-layer structure consisting of a ZnO matrix and Al{sub 2}O{sub 3} dopant layers, as determined by transmission electron microscopy analysis. In these layered AZO films, a single Al{sub 2}O{sub 3} dopant layer deposited during one ALD cycle could provide {approx}4.5 x 10{sup 13} cm{sup -2} free electrons to the ZnO. The effective field model for doping is suggested to explain the decrease in the carrier concentration of ALD-AZO films when the interval between the Al{sub 2}O{sub 3} layers is reduced to less than {approx}2.6 nm (>3.4 at% Al). By correlating the electrical and structural properties, an extrinsic doping mechanism of ALD-AZO films is proposed in which the incorporated Al atoms take oxygen from the ZnO matrix and form doubly charged donors, such as oxygen vacancies or zinc interstitials. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Electronic Structure and Magnetism of Mn-Doped ZnO Nanowires

    Directory of Open Access Journals (Sweden)

    Fuchun Zhang

    2015-05-01

    Full Text Available The geometric structures, electronic and magnetic properties of Mn-doped ZnO nanowires were investigated using density functional theory. The results indicated that all the calculated energy differences were negative, and the energy of the ground state was 0.229 eV lower than ferromagnetic coupling, which show higher stability in antiferromagnetic coupling. The calculated results indicated that obvious spin splitting phenomenon occurred near the Femi level. The Zn atoms on the inner layer of ZnO nanowires are easily substituted by Mn atoms along the [0001] direction. It was also shown that the Mn2+-O2−-Mn2+ magnetic coupling formed by intermediate O atom was proved to be caused by orbital hybridization between Mn 3d and O 2p states. The magnetic moments were mainly attributed to the unpaired Mn 3d orbitals, but not relevant with doping position of Mn atoms. Moreover, the optical properties of Mn-doped ZnO nanowires exhibited a novel blue-shifted optical absorption and enhanced ultraviolet-light emission. The above results show that the Mn-doped ZnO nanowires are a new type of magneto-optical materials with great promise.

  15. Influence of process parameters on band gap of AI-doped ZnO film

    Institute of Scientific and Technical Information of China (English)

    Diqiu HUANG; Xiangbin ZENG; Yajuan ZHENG; Xiaojin WANG; Yanyan YANG

    2013-01-01

    This paper presents the influence of process parameters, such as argon (Ar) flow rate, sputtering power and substrate temperature on the band gap of Al-doped ZnO film, Al-doped ZnO thin films were fabricated by radio frequency (RF) magnetron sputtering technology and deposited on polyimide and glass substrates. Under different Ar flow rates varied from 30 to 70 sccm, the band gap of thin films were changed from 3.56 to 3.67 eV. As sputtering power ranged from 125 to 200 W, the band gap was varied from 3.28 to 3.82 eV; the band gap was between 3.41 and 3.88 eV as substrate temperature increases from 150℃ to 300℃. Furthermore, the correlation between carrier concentration and band gap was investigated by HALL. These results demonstrate that the band gap of the Al-doped ZnO thin film can be adjusted by changing the Ar flow rate, sputtering power and substrate temperature, which can improve the performance of semiconductor devices related to Al-doped ZnO thin film.

  16. Microstructural and photoluminescence properties of sol–gel derived Tb3+ doped ZnO nanocrystals

    CSIR Research Space (South Africa)

    Kabongo, GL

    2014-04-01

    Full Text Available to further elucidate the wurtzitic structure of the prepared samples. PL study revealed that among different Tb(sup3+) concentrations, 0.5 mol% Tb(sup3+) doped ZnO nanoparticles showed clear emission from the dopant originating from the 4f–4f intra...

  17. CdS quantum dots sensitized Cu doped ZnO nanostructured thin films for solar cell applications

    Science.gov (United States)

    Poornima, K.; Gopala Krishnan, K.; Lalitha, B.; Raja, M.

    2015-07-01

    ZnO nanorods and Cu doped ZnO nanorods thin films have been prepared by simple hydrothermal method. CdS quantum dots are sensitized with Cu doped ZnO nanorod thin films using successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction study reveals that ZnO nanorods, and CdS quantum dot sensitized Cu doped ZnO nanorods exhibit hexagonal structure. The scanning electron microscope image shows the presence of ZnO nanorods. The average diameter and length of the aligned nanorod is 300 nm and 1.5 μm respectively. The absorption spectra shows that the absorption edge of CdS quantum dot sensitized ZnO nanorod thin film is shifted toward longer wavelength region when compared to the absorption edge of ZnO nanorods film. The conversion efficiency of the CdS quantum dot sensitized Cu doped ZnO nanorod thin film solar cell is 1.5%.

  18. Ferromagnetism of Mn-doped ZnO nanoparticles prepared by sol-gel process at room temperature

    Institute of Scientific and Technical Information of China (English)

    HUANG Gui-jun; WANG Jin-bin; ZHONG Xiang-li; ZHOU Gong-cheng; YAN Hai-long

    2006-01-01

    Mn-doped ZnO diluted magnetic semiconductor nanoparticles are prepared by an ultrasonic assisted sol gel process. Transmission electron microscopy shows pseudo-hexagonal nanoparticles with an average size of about 24 nm. From the analysis of X-ray diffraction,the Mn-doped ZnO nanoparticles are identified to be a wurtzite structure without any impurity phases. The magnetic properties are measured by using su perconducting quantum interference device. For the ZnO with 2 % Mn doping concentration, a good hyster esis loop indicates fine ferromagnetism with a Curie temperature higher than 350 K.

  19. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films.

    Science.gov (United States)

    Sreedharan, Remadevi Sreeja; Ganesan, Vedachalaiyer; Sudarsanakumar, Chellappan Pillai; Bhavsar, Kaushalkumar; Prabhu, Radhakrishna; Mahadevan Pillai, Vellara Pappukutty Pillai

    2015-01-01

    Background : Zinc oxide (ZnO) is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods : Europium oxide (Eu2O3) doped ZnO films are prepared on quartz substrate using radio frequency (RF) magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV)-visible spectroscopy and photoluminescence (PL) spectroscopy. Results : XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15-22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion : Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications.

  20. Highly textured and transparent RF sputtered Eu2O3 doped ZnO films

    Directory of Open Access Journals (Sweden)

    Remadevi Sreeja Sreedharan

    2015-03-01

    Full Text Available Background: Zinc oxide (ZnO is a wide, direct band gap II-VI oxide semiconductor. ZnO has large exciton binding energy at room temperature, and it is a good host material for obtaining visible and infrared emission of various rare-earth ions. Methods: Europium oxide (Eu2O3 doped ZnO films are prepared on quartz substrate using radio frequency (RF magnetron sputtering with doping concentrations 0, 0.5, 1, 3 and 5 wt%. The films are annealed in air at a temperature of 773 K for 2 hours. The annealed films are characterized using X-ray diffraction (XRD, micro-Raman spectroscopy, atomic force microscopy, ultraviolet (UV-visible spectroscopy and photoluminescence (PL spectroscopy. Results: XRD patterns show that the films are highly c-axis oriented exhibiting hexagonalwurtzite structure of ZnO. Particle size calculations using Debye-Scherrer formula show that average crystalline size is in the range 15–22 nm showing the nanostructured nature of the films. The observation of low- and high-frequency E2 modes in the Raman spectra supports the hexagonal wurtzite structure of ZnO in the films. The surface morphology of the Eu2O3 doped films presents dense distribution of grains. The films show good transparency in the visible region. The band gaps of the films are evaluated using Tauc plot model. Optical constants such as refractive index, dielectric constant, loss factor, and so on are calculated using the transmittance data. The PL spectra show both UV and visible emissions. Conclusion: Highly textured, transparent, luminescent Eu2O3 doped ZnO films have been synthesized using RF magnetron sputtering. The good optical and structural properties and intense luminescence in the ultraviolet and visible regions from the films suggest their suitability for optoelectronic applications.

  1. Effect of gallium concentrations on the morphologies, structural and optical properties of Ga-doped ZnO nanostructures.

    Science.gov (United States)

    Algarni, H; El-Gomati, M M; Al-Assiri, M S

    2014-07-01

    The effect of gallium ion concentrations (0.5 and 2%) on the morphologies, structural and optical properties of Ga-doped ZnO nanostructures are presented. Ga-doped ZnO nanostructures were synthesized on silicon substrates by simple thermal evaporation process using metallic zinc and Ga powders in the presence of oxygen. Interestingly, it was observed that Ga-ions incorporation in ZnO nanomaterials play an important role on the growth kinetics and hence on the morphologies of as-grown Ga-doped ZnO nanostructures. It was seen that at low Ga-concentration, needle-shaped Ga-doped ZnO nanostructures are formed, presumably by subsequent stacking of hexagonal plates. However, when increasing the Ga-concentration, multipods of Ga-doped ZnO were grown. In addition to the morphologies, incorporating Ga-ions into ZnO also affect the room-temperature photoluminescence properties. Therefore, at lower Ga-ion concentration, an intense UV emission was observed while at high Ga-concentration a deep level emission was seen in the room-temperature photoluminescence spectra. This research demonstrates that by controlling the Ga-ion concentration the morphologies and optical properties of ZnO nanomaterials can be tailored.

  2. Electrical transport and Al doping efficiency in nanoscale ZnO films prepared by atomic layer deposition

    NARCIS (Netherlands)

    Wu, Y.; Hermkens, P.M.; Loo, B.W.H. van de; Knoops, H.C.M.; Potts, S.E.; Verheijen, M.A.; Roozeboom, F.; Kessels, W.M.M.

    2013-01-01

    In this work, the structural, electrical, and optical properties as well as chemical bonding state of Al-doped ZnO films deposited by atomic layer deposition have been investigated to obtain insight into the doping and electrical transport mechanisms in the films. The range in doping levels from 0%

  3. Laser induced photoconductivity in sol–gel derived Al doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Eskandari, F.; Ranjbar, M., E-mail: ranjbar@cc.iut.ac.ir; Kameli, P.; Salamati, H.

    2015-11-15

    In this paper Al doped ZnO (AZO) thin films with 0, 3, 6 and 12 at. % Al concentration were prepared by sol–gel method on glass substrates. The deposited films were annealed at different temperatures of 300, 350, 400, 450 and 500 °C for 1 h in air. X-ray diffraction (XRD) showed wurtzite crystalline structure for the films annealed above 400 °C. The films were subsequently irradiated by beams of excimer (KrF, λ = 248 nm) laser. The evolution of crystal structure, surface morphology and optical properties were studied using XRD, filed emission scanning electron microscope (FE-SEM) and UV–Vis spectrophotometer, respectively. Real-time measurement of electrical conductivity during laser irradiation showed a transient or persistent photoconductivity effect. The effect of laser energy on this photoconductivity was also investigated. Based on the observed photoluminescence (PL) and X-ray photoelectron spectroscopy (XPS), the observed photoconductivity effect was described. - Highlights: • AZO (0–12 at. % Al) films were prepared by sol–gel method and annealed at different temperatures. • Excimer laser (λ = 248 nm) irradiation leads to improvement of crystalline structure. • Average optical transmission doesn't change and optical gap decreases by irradiation. • Photoconductivity was investigated by real-time measurement of electrical resistance. • Sample of 6% Al annealed at 450–500 °C showed the best photoconductivity effect.

  4. The shift of optical band gap in W-doped ZnO with oxygen pressure and doping level

    Energy Technology Data Exchange (ETDEWEB)

    Chu, J. [Department of Physics, University of Puerto Rico, San Juan, PR 00936-8377 (Puerto Rico); Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Science, Chongqing 400714 (China); Peng, X.Y.; Dasari, K.; Palai, R. [Department of Physics, University of Puerto Rico, San Juan, PR 00936-8377 (Puerto Rico); Feng, P., E-mail: p.feng@upr.edu [Department of Physics, University of Puerto Rico, San Juan, PR 00936-8377 (Puerto Rico)

    2014-06-01

    Highlights: • CVD–PLD co-deposition technique was used. • Better crystalline of the ZnO samples causes the redshift of the optical band gap. • Higher W concentration induces blueshift of the optical band gap. - Abstract: Tungsten-doped (W-doped) zinc oxide (ZnO) nanostructures were synthesized on quartz substrates by pulsed laser and hot filament chemical vapor co-deposition technique under different oxygen pressures and doping levels. We studied in detail the morphological, structural and optical properties of W-doped ZnO by SEM, XPS, Raman scattering, and optical transmission spectra. A close correlation among the oxygen pressure, morphology, W concentrations and the variation of band gaps were investigated. XPS and Raman measurements show that the sample grown under the oxygen pressure of 2.7 Pa has the maximum tungsten concentration and best crystalline structure, which induces the redshift of the optical band gap. The effect of W concentration on the change of morphology and shift of optical band gap was also studied for the samples grown under the fixed oxygen pressure of 2.7 Pa.

  5. Nickel tetraphenylporphyrin doping into ZnO nanoparticles for flexible dye-sensitized solar cell application

    Science.gov (United States)

    Shamimul Haque Choudhury, Mohammad; Kato, Shinya; Kishi, Naoki; Soga, Tetsuo

    2017-04-01

    In this study, we report on ZnO-based flexible dye-sensitized solar cells (DSCs) doped with different concentrations of 5,10,15,20-tetraphenyl-21H,23H-porphyrin nickel(II) (NiTPP). The photoelectrodes were prepared by blade coating, followed by a hot-compression technique. The effects of NiTPP doping on the surface morphology, structural, optical, and photovoltaic properties were studied. The surface morphology was observed by scanning electron microscopy (SEM), which confirmed the presence of NiTPP particles and also some aggregated particles visible at higher doping concentrations. The structural properties were examined by X-ray diffraction analysis and Raman spectroscopy, which confirmed the hexagonal wurtzite ZnO structure. The crystallite size of the ZnO nanoparticles (NPs) increased while the lattice strain decreased with increasing NiTPP doping concentration. The increment in the crystallite size might have induced light scattering inside the film to some extent. Optical absorption spectra showed the broadening of the spectrum in the lower-wavelength region, and a new absorption peak appeared (at 422 nm) as an effect of NiTPP doping. The red and blue shifts were observed for that peak as an effect of various doping concentrations. The Raman study of the films showed that there is no significant changes in the ZnO or NiTPP crystallite structure because of the NiTPP doping at different concentrations. Photocurrent-voltage (I-V) analysis showed that the 0.7%-NiTPP-doped cell attained the highest light-to-electric conversion efficiency of 2.7% in this investigation, which was about 42% higher than that of a non-NiTPP-doped cell.

  6. Eu-doped ZnO nanowire arrays grown by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Lupan, O., E-mail: oleg-lupan@chimie-paristech.fr [Laboratoire d’Electrochimie, Chimie des Interfaces et Modélisation pour l’Energie (LECIME), UMR-7575, ENSCP-Chimie Paristech, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); Laboratoire de Chimie de la Matière Condensée de Paris, UMR 7574, ENSCP, 11 rue P. et M. Curie, 75231 Paris cedex 05 (France); Department of Physics, University of Central Florida, Orlando, FL 32816 (United States); Department of Microelectronics and Semiconductor Devices, Technical University of Moldova, 168 Stefan cel Mare Blvd., Chisinau MD-2004, Republic of Moldova (Moldova, Republic of); Pauporté, T., E-mail: thierry-pauporte@chimie-paristech.fr [Laboratoire d’Electrochimie, Chimie des Interfaces et Modélisation pour l’Energie (LECIME), UMR-7575, ENSCP-Chimie Paristech, 11 rue Pierre et Marie Curie, 75231 Paris cedex 05 (France); Viana, B.; Aschehoug, P. [Laboratoire de Chimie de la Matière Condensée de Paris, UMR 7574, ENSCP, 11 rue P. et M. Curie, 75231 Paris cedex 05 (France); Ahmadi, M.; Cuenya, B. Roldan; Rudzevich, Y.; Lin, Y.; Chow, L. [Department of Physics, University of Central Florida, Orlando, FL 32816 (United States)

    2013-10-01

    The preparation of efficient light emitting diodes requires active optical layers working at low voltage for light emission. Trivalent lanthanide doped wide-bandgap semiconducting oxide nanostructures are promising active materials in opto-electronic devices. In this work we report on the electrochemical deposition (ECD) of Eu-doped ZnO (ZnO:Eu) nanowire arrays on glass substrates coated with F-doped polycrystalline SnO{sub 2}. The structural, chemical and optical properties of ZnO:Eu nanowires have been systematically characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and photoluminescence. XRD results suggest the substitution of Zn{sup 2+} by Eu ions in the crystalline lattice. High-resolution TEM and associated electron diffraction studies indicate an interplanar spacing of 0.52 nm which corresponds to the (0 0 0 1) crystal plane of the hexagonal ZnO, and a growth along the c-direction. The ZnO:Eu nanowires have a single crystal structure, without noticeable defects. According to EDX, SIMS and XPS studies, cationic Eu species are detected in these samples showing the incorporation of Eu into the ZnO matrix. The oxidation states of europium ions in the nanowires are determined as +3 (74%) and +2 (26%). Photoluminescence studies demonstrated red emission from the Eu-doped ZnO nanowire arrays. When Eu was incorporated during the nanowire growth, the sharp {sup 5}D{sub 0}–{sup 7}F{sub 2} transition of the Eu{sup 3+} ion at around 612 nm was observed. These results suggest that Eu doped ZnO nanowires could pave the way for efficient, multispectral LEDs and optical devices.

  7. Photoluminescence and Raman studies for the confirmation of oxygen vacancies to induce ferromagnetism in Fe doped Mn:ZnO compound

    Energy Technology Data Exchange (ETDEWEB)

    Das, J., E-mail: jayashree304@gmail.com [Department of Physics, Silicon Institute of Technology, Bhubaneswar 751024, Odisha (India); Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710 (South Africa); Mishra, D.K. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710 (South Africa); Department of Physics, Institute of Technical Education and Research, Siksha ‘O’ Anusandhan University, Khandagiri Square, Bhubaneswar 751030, Odisha (India); Srinivasu, V.V. [Department of Physics, College of Science, Engineering and Technology, University of South Africa, Johannesburg 1710 (South Africa); Sahu, D.R. [Amity Institute of Nanotechnology, Amity University, Noida (India); Roul, B.K. [Institute of Materials Science, Planetarium Building, Acharya Vihar, Bhubaneswar, Odisha (India)

    2015-05-15

    With a motivation to compare the magnetic property, we synthesised undoped, transition metal (TM) Mn doped and (Mn:Fe) co-doped ZnO ceramics in the compositions ZnO, Zn{sub 0.98}Mn{sub 0.02}O and Zn{sub 0.96}(Mn{sub 0.02}Fe{sub 0.02})O. Systematic investigations on the structural, microstructural, defect structure and magnetic properties of the samples were performed. Low temperature as well as room temperature ferromagnetism has been observed for all our samples, however, enhanced magnetisation at room temperature has been noticed when ZnO is co-doped with Fe along with Mn. Particularly the sample with the composition Zn{sub 0.96}Mn{sub 0.02}Fe{sub 0.02}O showed a magnetisation value more than double of the sample with composition Zn{sub 0.98}Mn{sub 0.02}O, indicating long range strong interaction between the magnetic impurities leading to higher ferromagnetic ordering. Raman and PL studies reveal presence of higher defects in form of oxygen vacancy clusters created in the sample due to Fe co doping. PL study also reveals enhanced luminescence efficiency in the co doped sample. Temperature dependent magnetisation study of this sample shows the spin freezing temperature around 39 K indicating the presence of small impurity phase of Mn{sub 2−x}Zn{sub x}O{sub 3} type. Electron Spin Resonance signal obtained supports ferromagnetic state in the co doped sample. Enhancement of magnetisation is attributed to interactions mediated by magnetic impurities through large number of oxygen vacancies created by Fe{sup 3+} ions forming bound magnetic polarons (BMP) and facilitating long range ferromagnetic ordering in the co- doped system. - Highlights: • Comparison of magnetic property of ZnO, Zn{sub 0.98}Mn {sub 0.02}O and Zn{sub 0.96}(Mn{sub 0.02}Fe{sub 0.02})O. • Observation of enhanced magnetisation at room temperature in (Mn,Fe) doped ZnO. • Raman and PL studies reveal presence of higher oxygen vacancy clusters. • Electron Spin Resonance signal supports

  8. Room temperature DC magnetron sputtering deposition and field emission of Al-doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Fan; Cai, Xing-Min; Zhang, Dong-Ping; Fan, Ping; Liu, Li-Jun [School of Physical Science and Technology and Shenzhen Key Laboratory of Sensor Technologies, Shenzhen University, Shenzhen 518060 (China); Dai, Fu-Ping [Department of Applied Physics, Northwestern Polytechnic University, Xian 710072 (China)

    2011-08-15

    Al doped ZnO films were prepared by reactive direct current (DC) magnetron sputtering at room temperature. The targets were metallic Al and Zn while the gases were Ar and O{sub 2}. X-ray diffraction (XRD) shows that the films are of hexagonal structure and Al is successfully doped into ZnO without secondary phases detected. Raman scattering spectra of the films contain the E{sub 1} mode of ZnO. Seebeck effect shows that the films are n-type and four probe instrument shows that the films are very resistive. The high resistivity is due to the compensation of acceptors such as oxygen vacancies and substitutional nitrogen atoms. The acceptors reduce the electron density and increase the work function of ZnO, which therefore weakens the field emission of Al doped ZnO films. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Influence of In doping on electro-optical properties of ZnO films

    Indian Academy of Sciences (India)

    A P Rambu; D Sirbu; A V Sandu; G Prodan; V Nica

    2013-04-01

    Thin metallic films of Zn and In/Zn were deposited onto glass substrates by thermal evaporation under vacuum. The metallic films were submitted to a thermal oxidation in air, at 623 K, for different oxidation times (30–90 min), in order to be oxidized. Structural andmorphological analyses (X-ray diffraction, transmission electron microscopy and scanning electron microscopy) revealed that the obtained undoped and In-doped ZnO thin films possess a polycrystalline structure. Transmission spectra were recorded in spectral domain from 280 to 1400 nm. The influence of In doping and oxidation parameters as well, on the optical parameters (transmittance, optical bandgap, Urbach energy) were analysed. It was clearly evidenced that by In doping, the optical properties of ZnO films were improved. The temperature dependence of electrical conductivity was studied using surface-type cells with Ag electrodes. The obtained results indicate that In-doped ZnO films exhibit an enhancement of electrical conductivity with few orders of magnitude when compared with non-doped ones.

  10. Enhanced piezoelectric output voltage and Ohmic behavior in Cr-doped ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Nidhi [Crystal Lab, Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Department of Electronics, SGTB Khalsa College, University of Delhi, Delhi 110007 (India); Ray, Geeta; Godara, Sanjay; Gupta, Manoj K. [Crystal Lab, Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Kumar, Binay, E-mail: bkumar@physics.du.ac.in [Crystal Lab, Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2014-11-15

    Highlights: • Low cost highly crystalline Cr-doped ZnO nanorods were synthesized. • Enhancement in dielectric, piezoelectric and ferroelectric properties were observed. • A high output voltage was obtained in AFM. • Cr-doping resulted in enhanced conductivity and better Ohmic behavior in ZnO/Ag contact. - Abstract: Highly crystalline Cr-doped ZnO nanorods (NRs) were synthesized by solution technique. The size distribution was analyzed by high resolution tunneling electron microscope (HRTEM) and particle size analyzer. In atomic force microscope (AFM) studies, peak to peak 8 mV output voltage was obtained on the application of constant normal force of 25 nN. It showed high dielectric constant (980) with phase transition at 69 °C. Polarization vs. electric field (P–E) loops with remnant polarization (6.18 μC/cm{sup 2}) and coercive field (0.96 kV/cm) were obtained. In I–V studies, Cr-doping was found to reduce the rectifying behavior in the Ag/ZnO Schottky contact which is useful for field effect transistor (FET) and solar cell applications. With these excellent properties, Cr-doped ZnO NRs can be used in nanopiezoelectronics, charge storage and ferroelectric applications.

  11. The magnetic ordering in high magnetoresistance Mn-doped ZnO thin films

    KAUST Repository

    Venkatesh, S.

    2016-03-24

    We studied the nature of magnetic ordering in Mn-doped ZnO thin films that exhibited ferromagnetism at 300 K and superparamagnetism at 5 K. We directly inter-related the magnetisation and magnetoresistance by invoking the polaronpercolation theory and variable range of hopping conduction below the metal-to-insulator transition. By obtaining a qualitative agreement between these two models, we attribute the ferromagnetism to the s-d exchange-induced spin splitting that was indicated by large positive magnetoresistance (∼40 %). Low temperature superparamagnetism was attributed to the localization of carriers and non-interacting polaron clusters. This analysis can assist in understanding the presence or absence of ferromagnetism in doped/un-doped ZnO.

  12. Voltage threshold behaviors of ZnO nanorod doped liquid crystal cell

    Institute of Scientific and Technical Information of China (English)

    Guo Yubing; Chen Yonghai; Xiang Ying; and Qu Shengchun

    2011-01-01

    With ZnO nanorods doped in only one poly (vinyl alcohol) (PVA) layer,we observed different threshold voltages with reverse DC voltages for a liquid crystal cell.The length and diameter of the ZnO nanorod used in our experiment were about 180 nm and 20 nm,respectively.When the PVA layer on the anodic side was doped,the threshold voltage was larger than that of the pure cell; conversely,when the PVA layer on the cathodic side was doped,the threshold voltage was smaller than that of the pure cell.These results can be explained by the internal electric field model.We also observed a resonance phenomenon with a low frequency AC voltage.

  13. Structural, morphological and photoluminescence properties of W-doped ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Ngom, B.D., E-mail: bdngom@tlabs.ac.za [Groupes de physique du Solide et Sciences des Materiaux (GPSSM), Faculte des Sciences et Techniques Universite Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal); NANO-Sciences Laboratories, Materials Research Group, iThemba LABS, National Research Foundation (South Africa); Sakho, O. [Groupes de physique du Solide et Sciences des Materiaux (GPSSM), Faculte des Sciences et Techniques Universite Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal); Manyala, N. [Department of Physics, Institute of Materials, University of Pretoria, Pretoria (South Africa); Kana, J.B. [Departement de physique, Universite Yaounde 1, Yaounde (Cameroon); Mlungisi, N. [NANO-Sciences Laboratories, Materials Research Group, iThemba LABS, National Research Foundation (South Africa); Guerbous, L. [Nuclear Research Center of Algiers - CRNA, 02 Bd Frantz Fanon BP 399 Alger Gare, Algiers (Algeria); Fasasi, A.Y. [Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Osun State (Nigeria); Maaza, M. [NANO-Sciences Laboratories, Materials Research Group, iThemba LABS, National Research Foundation (South Africa); Beye, A.C. [Groupes de physique du Solide et Sciences des Materiaux (GPSSM), Faculte des Sciences et Techniques Universite Cheikh Anta Diop de Dakar (UCAD), B.P. 25114, Dakar-Fann Dakar (Senegal)

    2009-05-30

    W-doped ZnO nanostructures were synthesized at substrate temperature of 600 deg. C by pulsed laser deposition (PLD), from different wt% of WO{sub 3} and ZnO mixed together. The resulting nanostructures have been characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and photoluminescence for structural, surface morphology and optical properties as function of W-doping. XRD results show that the films have preferred orientation along a c-axis (0 0 L) plane. We have observed nanorods on all samples, except that W-doped samples show perfectly aligned nanorods. The nanorods exhibit near-band-edge (NBE) ultraviolet (UV) and violet emissions with strong deep-level blue emissions and green emissions at room temperature.

  14. Photocatalytic enhancement of Mg-doped ZnO nanocrystals hybridized with reduced graphene oxide sheets

    Institute of Scientific and Technical Information of China (English)

    Linqin Wang; Yan Wun; Fangyuan Chen; Xiang Yang

    2014-01-01

    Hybridization of Mg-doped ZnO and reduced graphene oxide (MZO-RGO) were synthesized through one pot reaction process. Crystallization of MZO-RGO upon thermal decomposition of the stearate precursors was investigated by X-ray diffraction technique. XRD studies point toward the particles size with 10-15 nm, which was confirmed by transmittance electronic microscopy, and also indicates that graphene oxide has been directly reduced into its reduced state graphene during the synthesis. Graphene hybridized MZO photocatalyst showed enhanced catalytic activity for the degradation of methylene blue (MB). The degree of photocatalytic activity enhancement strongly depended both on the coverage of graphene on the surface of MZO nanoparticles and the Mg doping concentration. The sample of 2 wt%graphene hybridized 5 at%Mg-doped ZnO showed the highest photocatalytic activity, which remained good photocatalytic activity after nine cycling runs.

  15. Linear and nonlinear optical investigations of nano-scale Si-doped ZnO thin films: spectroscopic approach

    Science.gov (United States)

    Jilani, Asim; Abdel-wahab, M. Sh.; Zahran, H. Y.; Yahia, I. S.; Al-Ghamdi, Attieh A.

    2016-09-01

    Pure and Si-doped ZnO (SZO) thin films at different concentration of Si (1.9 and 2.4 wt%) were deposited on highly cleaned glass substrate by radio frequency (DC/RF) magnetron sputtering. The morphological and structural investigations have been performed by atomic force electron microscope (AFM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy was employed to study the composition and the change in the chemical state of Si-doped ZnO thin films. The optical observations like transmittance, energy band gap, extinction coefficient, refractive index, dielectric loss of pure and Si-doped ZnO thin films have been calculated. The linear optical susceptibility, nonlinear refractive index, and nonlinear optical susceptibility were also studied by the spectroscopic approach rather than conventional Z-scan method. The energy gap of Si-doped ZnO thin films was found to increase as compared to pure ZnO thin films. The crystallinity of the ZnO thin films was effected by the Si doping. The O1s spectra in pure and Si-doped ZnO revealed the bound between O-2 and Zn+2 ions and reduction in the surface oxygen with the Si doping. The chemical state analysis of Si 2p showed the conversation of Si to SiOx and SiO2. The increase in the first-order linear optical susceptibility χ (1) and third-order nonlinear optical susceptibility χ (3) was observed with the Si doping. The nonlinear studies gave some details about the applications of metal oxides in nonlinear optical devices. In short, this study showed that Si doping through sputtering has effected on the structural, surface and optical properties of ZnO thin films which could be quite useful for advanced applications such as metal-oxide-based optical devices.

  16. Magnetic properties in (Mn,Fe)-codoped ZnO nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Huawei [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Lu, Pengfei, E-mail: photon.bupt@gmail.com [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Cong, Zixiang [School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100976 (China); Yu, Zhongyuan; Cai, Ningning; Zhang, Xianlong [Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), Ministry of Education, Beijing 100876 (China); Gao, Tao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Wang, Shumin [Photonics Laboratory, Department of Microtechnology and Nanoscience, Chalmers University of Technology, 41296 Gothenburg (Sweden); State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2013-12-02

    Using the first-principles density functional theory, we have studied the electronic structures and magnetic properties of Mn/Fe codoped ZnO nanowires systematically. The calculated results of formation energy indicate that the configuration of the lowest energy where Mn and Fe atoms form nearest neighbors on the outer cylindrical surface layer along the [0001] direction, will be determined. The magnetic coupling of 8 types of Mn/Fe codoped ZnO nanowires was investigated and ferromagnetic state was found in certain configurations. The mechanism is from the fierce hybridization between 3d of Mn and Fe with O 2p near the Fermi level. The relative energy difference for configuration VIII is 0.221 eV, which indicates that room temperature ferromagnetism could be obtained in such a system and Mn/Fe codoped ZnO nanowires are a promising nanoscale spintronic material. - Highlights: • The stable structure prefers that Mn/Fe form nearest neighbors on the outer surface. • The fierce p–d hybridization is responsible for ferromagnetic (FM) coupling. • Mn/Fe codoped ZnO nanowire is a promising FM semiconductor material.

  17. Electronic and Optical Properties of Substitutional and Interstitial Si-Doped ZnO

    Directory of Open Access Journals (Sweden)

    Tsu-Ping Shen

    2012-10-01

    Full Text Available This study investigates the formation energies, electronic structures, and optical properties of pure and Si-doped ZnO using density functional theory and the Hubbard U (DFT + Ud + Up method. The difference in lattice constants between calculated results and experimental measurements is within 1%, and the calculated band gap of pure ZnO is in excellent agreement with experimental values. This study considers three possible Si-doped ZnO structures including the substitution of Si for Zn (Sis(Zn, interstitial Si in an octahedron (Sii(oct, and interstitial Si in a tetrahedron (Sii(tet. Results show that the formation energy of Sis(Zn defects is the lowest, indicating that Sis(Zn defects are formed more easily than Sii(oct and Sii(tet. All three of the Si defect models exhibited n-type conductive characteristics, and except for the Sii(oct mode the optical band gap expanded beyond that of pure ZnO. In both the Sii(oct and Sii(tet models, a heavier effective mass decreased carrier mobility, and deeper donor states significantly decreased transmittance. Therefore, the existence of interestitial Si atoms was bad for the electric and optical properties of ZnO.

  18. Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases.

    Science.gov (United States)

    Dilonardo, Elena; Penza, Michele; Alvisi, Marco; Di Franco, Cinzia; Palmisano, Francesco; Torsi, Luisa; Cioffi, Nicola

    2016-01-01

    A one-step electrochemical method based on sacrificial anode electrolysis (SAE) was used to deposit stabilized gold nanoparticles (Au NPs) directly on the surface of nanostructured ZnO powders, previously synthesized through a sol-gel process. The effect of thermal annealing temperatures (300 and 550 °C) on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO) was investigated. Transmission and scanning electron microscopy (TEM and SEM), as well as X-ray photoelectron spectroscopy (XPS), revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

  19. Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

    Directory of Open Access Journals (Sweden)

    Elena Dilonardo

    2016-01-01

    Full Text Available A one-step electrochemical method based on sacrificial anode electrolysis (SAE was used to deposit stabilized gold nanoparticles (Au NPs directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO was investigated. Transmission and scanning electron microscopy (TEM and SEM, as well as X-ray photoelectron spectroscopy (XPS, revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

  20. Antibacterial properties of F-doped ZnO visible light photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Podporska-Carroll, Joanna, E-mail: joannapcarroll@gmail.com [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); Myles, Adam [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin St., Dublin (Ireland); Quilty, Brid [School of Biotechnology, Dublin City University, Dublin (Ireland); McCormack, Declan E.; Fagan, Rachel [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); School of Chemical and Pharmaceutical Sciences, Dublin Institute of Technology, Kevin St., Dublin (Ireland); Hinder, Steven J. [The Surface Analysis Laboratory, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, Department of Biomedical, Chemical and Environmental Engineering (DBCEE), 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Pillai, Suresh C., E-mail: Pillai.Suresh@itsligo.ie [Center for Research in Engineering Surface Technology (CREST), DIT FOCAS Institute, Kevin St., Dublin (Ireland); Nanotechnology Research Group, Department of Environmental Science, PEM Centre, Institute of Technology Sligo, Sligo (Ireland)

    2017-02-15

    Highlights: • F doped ZnO nano-powders were obtained by a modified sol–gel method. • These materials were found to be effective against S. aureus and E. coli. • Enhanced visible light photocatalytic and antimicrobial properties were obtained. • The toxic effect of ZnO on bacteria can be due to the release of zinc cations. • Production of reactive oxidation species influences bacterial viability. - Abstract: Nanocrystalline ZnO photocatalysts were prepared by a sol–gel method and modified with fluorine to improve their photocatalytic anti-bacterial activity in visible light. Pathogenic bacteria such as Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) were employed to evaluate the antimicrobial properties of synthesized materials. The interaction with biological systems was assessed by analysis of the antibacterial properties of bacteria suspended in 2% (w/w) powder solutions. The F-doping was found to be effective against S. aureus (99.99% antibacterial activity) and E. coli (99.87% antibacterial activity) when irradiated with visible light. Production of reactive oxygen species is one of the major factors that negatively impact bacterial growth. In addition, the nanosize of the ZnO particles can also be toxic to microorganisms. The small size and high surface-to-volume ratio of the ZnO nanoparticles are believed to play a role in enhancing antimicrobial activity.

  1. Some physical investigations on hexagonal-shaped nanorods of lanthanum-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Mrabet, C.; Kamoun, O.; Boukhachem, A., E-mail: abdelwaheb.boukhachem@laposte.net; Amlouk, M.; Manoubi, T.

    2015-11-05

    Lanthanum-doped Zinc oxide (ZnO:La) thin films were successfully grown on glass substrates by the spray pyrolysis technique at 460 °C. Alternatively, some of the obtained films were doped with lanthanum at the molar rates of: 1, 2, 3 and 4%. The structural properties of the prepared samples were characterized by X-ray diffraction (XRD) technique and scanning electron microscopy (SEM). It is shown that ZnO:La thin films crystallize in hexagonal wurtzite structure with a preferred orientation of the crystallites along (002) direction. Also, Raman spectroscopy shows the bands corresponding to ZnO structure and confirms the presence of La{sub 2}O{sub 3} secondary phase. Furthermore, it is found that the lattice parameters a and c of La-doped ZnO films decrease with La content. UV–vis measurements show that the average transmittance of the ZnO:La thin films is 75% and the average reflectance is less than 25% in the visible range. In the same line, it is noted that the optical band gap, Urbach energy, and the optical constants are significantly influenced by the lanthanum incorporation. The photoluminescence (PL) measurements exhibit emission in the visible region (a strong band located around 480 nm and a weak band around 420 nm). The intensity of level emission varies with La doping. Moreover, it is observed a significant variation of both electrical resistivity and activation energy with La concentration. The electrical conductivity of films dependence of temperature was measured to reach the dominant conductivity mechanism. - Highlights: • La doped ZnO nanorods have been synthesized by facile spray pyrolysis method. • Influences of doping on the surface and optical properties of the ZnO films were investigated. • The photoluminescence show the effect of La incorporation on optical properties. • La doped ZnO films indicate high transparency in visible range. • Highly c-axis oriented ZnO nanorods were grown on glass substrates.

  2. Preparation and characterization of undoped and cobalt doped ZnO for antimicrobial use.

    Science.gov (United States)

    Stoica, Angelica Oprea; Andronescu, Ecaterina; Ghitulica, Cristina Daniela; Voicu, Georgeta; Grumezescu, Alexandru Mihai; Popa, Marcela; Chifiriuc, Mariana Carmen

    2016-08-30

    The objective of this study was to carry out the synthesis by sol-gel method of undoped and cobalt doped ZnO, with different cobalt concentrations (0.5-5mol%), using as stabilizer monoethanolamine (MEA) in a molar ratio ZnO:MEA=1:2. The dry gel was thermally treated at 500°C/5h, respectively at 1100°C/30min. All the thermal treated samples were of wurtzite type with an hexagonal structure. The doping with Co(2+) induced change of lattice parameters and of crystallite size, proving the successful interleaving of Co(2+) into the ZnO lattice. From the morphological point of view, the thermal treatment at 1100°C/30min led to a higher degree of compactness of the ZnO granules. At 500°C/5h there were formed polyhedral or spherical nanometric particles (25-50nm) which have been agglomerated into aggregates with sizes over 1μm. From the biological point of view, the quantitative analyses of antimicrobial activity have shown that the ZnO doped with cobalt has inhibited the ability of the Bacillus subtilis and Escherichia coli bacterial strains to colonize the inert substrate and therefore, can be used in the design of new antimicrobial strategies.

  3. Structural and electronic properties of Eu- and Pd-doped ZnO

    Directory of Open Access Journals (Sweden)

    Zhang Yuebin

    2011-01-01

    Full Text Available Abstract Doping ZnO with rare earth and 4d transition elements is a popular technique to manipulate the optical properties of ZnO systems. These systems may also possess intrinsic ferromagnetism due to their magnetic moment borne on 4f and 4d electrons. In this work, the structural, electronic, and magnetic properties of Eu- and Pd-doped ZnO were investigated by the ab initio density functional theory methods based on generalized gradient approximation. The relative stability of incorporation sites of the doped elements in the ZnO host lattice was studied. The ground state properties, equilibrium bond lengths, and band structures of both the ZnO:Eu and ZnO:Pd systems were also investigated. The total and partial densities of electron states were also determined for both systems. It was found that in the ZnO:Eu system, ambient ferromagnetism can be induced by introducing Zn interstitial which leads to a carrier-mediated ferromagnetism while the ZnO:Pd system possesses no ferromagnetism. PACS 31.15.E-, 75.50.Pp, 75.30Hx

  4. Co-doped branched ZnO nanowires for ultraselective and sensitive detection of xylene.

    Science.gov (United States)

    Woo, Hyung-Sik; Kwak, Chang-Hoon; Chung, Jae-Ho; Lee, Jong-Heun

    2014-12-24

    Co-doped branched ZnO nanowires were prepared by multistep vapor-phase reactions for the ultraselective and sensitive detection of p-xylene. Highly crystalline ZnO NWs were transformed into CoO NWs by thermal evaporation of CoCl2 powder at 700 °C. The Co-doped ZnO branches were grown subsequently by thermal evaporation of Zn metal powder at 500 °C using CoO NWs as catalyst. The response (resistance ratio) of the Co-doped branched ZnO NW network sensor to 5 ppm p-xylene at 400 °C was 19.55, which was significantly higher than those to 5 ppm toluene, C2H5OH, and other interference gases. The sensitive and selective detection of p-xylene, particularly distinguishing among benzene, toluene, and xylene with lower cross-responses to C2H5OH, can be attributed to the tuned catalytic activity of Co components, which induces preferential dissociation of p-xylene into more active species, as well as the increase of chemiresistive variation due to the abundant formation of Schottky barriers between the branches.

  5. Ferromagnetism induced by the charge transfer in Al-doped ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yanyu; Zhou, Wei; Wu, Ping, E-mail: pingwu@tju.edu.cn

    2014-12-05

    Highlights: • A systematical investigation has been carried out on Zn{sub 1−x}Al{sub x}O system. • Our results confirm that Zn{sub 1−x}Al{sub x}O nanoparticles are magnetic. • The magnetism originates from charge transfer between different cations. • The accordant conclusion is drawn both theoretically and experimentally. • The ferromagnetism would render it to realize more comprehensive applications. - Abstract: The mechanism of ferromagnetism in Al-doped ZnO was investigated both theoretically and experimentally. The density functional theory calculations were carried out to explore the electronic structure origin of ferromagnetism. The Al dopants both doping in a bulk ZnO and absorbing on the ZnO surface are taken into account. Based on the Bader charge analysis for the clear and adsorbed ZnO surface, it is found that the ionic state of Zn decreases after Al doping. The corresponding room temperature ferromagnetism was also confirmed by experiments. Moreover, the experimental analysis rules out that the ferromagnetism results from zinc vacancy or oxygen vacancy. Thus, the physical origin of the induced magnetism was indicated originating from the charge transfer between Zn atoms and adsorbed Al atoms.

  6. Room temperature ferromagnetism in Cd-doped ZnO thin films through defect engineering

    Energy Technology Data Exchange (ETDEWEB)

    Debbichi, M., E-mail: mourad_fsm@yahoo.fr [Laboratoire de la matière condensée et nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Souissi, M. [College of Arts and Science Nayriya, Dammam University, 31441 Dammam (Saudi Arabia); Fouzri, A. [Laboratoire Physico-Chimie des Matériaux, Unité de Service Commun de Recherche ‘‘High Resolution X-ray Diffractometer’’, Département de Physique, Université de Monastir, Faculté des Sciences de Monastir, Avenue de l’Environnement, 5019 Monastir (Tunisia); Schmerber, G. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) UMR 7504 CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France); Said, M. [Laboratoire de la matière condensée et nanosciences, Département de Physique, Faculté des Sciences de Monastir, 5019 Monastir (Tunisia); Alouani, M. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS) UMR 7504 CNRS-Université de Strasbourg, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France)

    2014-06-15

    Highlights: • ZnO:Cd thin film grown on c-sapphire substrate by MOCVD method. • RTFM in ZnO:Cd thin film is detected by SQUID magnetometer measurement. • DFT theory is conducted to elucidate the mechanism of RTFM in Cd-doped ZnO. - Abstract: Room-temperature ferromagnetism is detected in undoped and cadmium-doped ZnO (ZnO:Cd) thin film grown on c-plane sapphire substrate by metal–organic chemical vapor deposition method. To elucidate the origin of ferromagnetism, a theoretical study based on density functional theory is conducted, focusing on the role of the neutral cation vacancy on the appearance of magnetism in Cd-doped ZnO thin film. The calculations revealed that Cd substitution at Zn sites contributes to the long-ranged ferromagnetism in ZnO by lowering the formation energy of Zn vacancies and thereby stabilizing Zn vacancies from which the magnetic moments originate.

  7. Microstructural analysis and thermoelectric properties of Sn-Al co-doped ZnO ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Hoemke, Joshua, E-mail: jhoemke@sigma.t.u-tokyo.ac.jp; Tochigi, Eita; Shibata, Naoya; Ikuhara, Yuichi [Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Khan, Atta Ullah; Mori, Takao [National Institute of Materials Science (NIMS) 1-1 Namiki, Tsukuba 305-0044 (Japan); Yoshida, Hidehiro; Sakka, Yoshio [National Institute of Materials Science (NIMS), 1–2–1 Sengen, Tsukuba, 305–0047 (Japan)

    2016-08-26

    Sn-Al co-doped polycrystalline ZnO ceramics were prepared by sintering in air. Phase and microstructure analysis was performed by X-ray diffraction and SEM-EDS and thermoelectric properties were measured. XRD analysis showed a ZnO primary phase as well as secondary phase peaks due to the formation of a Zn{sub 2}SnO{sub 4} spinel phase or SnO{sub 2}(ZnO:Sn-Al){sub m} intergrowth phase. SEM analysis revealed a dense microstructure with a small number of nanometric pores, consistent with the measured density of 5.48 g/cm{sup 3}. An activated electrical conductivity characteristic of a semiconducting material was observed as well as a negative Seebeck coefficient with both values increasing in absolute value from RT to 730 °C. The power factor had a maximum value of 3.73×10{sup −4} W m{sup −1} K{sup −2} at 730 °C. Thermal conductivity measurements showed a significant reduction over the measured temperature range compared to undoped ZnO. This could be attributed to grain size reduction, the formation of a nanoscale secondary phase or a reduction in crystallinity caused by Sn-Al co-doping. A maximum ZT of 0.06 was obtained at 750 °C for the Sn-Al co-doped ZnO ceramics.

  8. Microstructural and Mechanical Studies of PVA Doped with ZnO and WO3 Composites Films

    Directory of Open Access Journals (Sweden)

    N. B. Rithin Kumar

    2014-01-01

    Full Text Available Polymer composites of ZnO and WO3 nanoparticles doped polyvinyl alcohol (PVA matrix have been prepared using solvent casting method. The microstructural properties of prepared films were studied using FTIR, XRD, SEM, and EDAX techniques. In the doped PVA, many irregular shifts in the FTIR spectra have been observed and these shifts in bands can be understood on the basis of intra/intermolecular hydrogen bonding with the adjacent OH group of PVA. The chemical composition, phase homogeneity, and morphology of the polymer composites of the polymer film were studied using EDAX and SEM. These data indicate that the distribution of nanosized ZnO and WO3 dopants is uniform and confirm the presence of ZnO and WO3 in the film. The crystal structure and crystallinity of polymer composites were studied by XRD. It was found that the change in structural repositioning and crystallinity of the composites takes place due to the interaction of dopants and also due to complex formation. The mechanical studies of doped polymer films were carried out using universal testing machine (UTM at room temperature, indicating that the addition of the ZnO and WO3 with weight percentage concentration equal to 14% increases the tensile strength and Young’s modulus.

  9. Effect of Sb-doping on the morphology and dielectric properties of chrysanthemum-like ZnO nanowire clusters

    Institute of Scientific and Technical Information of China (English)

    Yan Jun-Feng; You Tian-Gui; Zhang Zhi-Yong; Tian Jiang-Xiao; Yun Jiang-Ni; Zhao Wu

    2012-01-01

    Chrysanthemum-like ZnO nanowire clusters with different Sb-doping concentrations were prepared using a hydrothermal process. The microstructures,morphologies,and dielectric properties of the as-prepared products were characterized by X-ray diffraction (XRD),high-resolution transmission electron microscopy (HRTEM),field emission environment scanning electron microscope (FEESEM),and microwave vector network analyzer respectively.The results indicate that the as-prepared products are Sb-doped ZnO single crystallines with a hexagonal wurtzite structure,the flower bud saturation degree Fd is obviously different from that of the pure ZnO nanowire clusters,the good dielectric loss property is found in Sb-doped ZnO products with low density,and the dielectric loss tangent tanδe increases with the increase of the Sb-doping concentration in a certain concentration range.

  10. Enhanced photocatalytic activity of Ce-doped ZnO nanopowders synthesized by combustion method

    Institute of Scientific and Technical Information of China (English)

    洪樟连

    2015-01-01

    Facile and fast combustion method was used to synthesize ZnO and Ce-doped ZnO (CZO) nanocrystalline powders photo-catalysts with different cerium concentrations (0.5 wt.%–10.0 wt.%) followed by calcination at 700 ºC for 3 h. The prepared samples were characterized by a variety of characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) combined with energy dispersive X-ray diffraction (EDX), transmission electron microscopy (TEM), UV-visible spectroscopy, BET surface area analyser and photoluminescence spectroscopy (PL), to study the crystal structure, surface morphology, chemical compo-sition and optical properties. It was observed from XRD results that synthesized powders had hexagonal wurtzite structure with the smallest crystallite size about 13 nm. Absorption spectra showed that cerium doping enhanced the light absorption properties towards the visible light region. Photoluminescence spectra for Ce-doped ZnO samples exhibited relatively weak near band edge (NBE) emis-sion peaks as compared to that of pristine ZnO. The photocatalytic activities of the prepared samples were evaluated by photocatalytic degradation of Rhodamine B (RhB) under UV light and visible light (λ≥420 nm) irradiation. The textile mill effluent containing or-ganic matters was also treated under sunlight using photocatalysis and the reduction in the chemical oxygen demand (COD) of the treated effluent revealed a complete destruction of the organic molecules along with colour removal. The results showed that the CZO photocatalyst doped with 3.0 wt.% cerium exhibited four times enhanced photocatalytic activity compared to pure ZnO. The en-hanced photocatalytic activity could be attributed to extended visible light absorption and inhibition of the electron-hole pair’s recom-bination.

  11. Performance Evaluation of ZnO based Rare Earth Element Doped Thin Films

    Directory of Open Access Journals (Sweden)

    Manish Sharma

    2013-10-01

    Full Text Available In DMS materials, a small fraction of a host semiconductor cation is substituted by magnetic ions. We chose as semiconducting host the transparent ZnO, with a bandgap of 3.3 eV at room temperature. Studies on ZnO doped with 3d transition metals indicated only small magnetic moments. The more recent results for Gd in GaN, indicating high magnetic moments, motivated us to investigate ZnO thin films doped with rare earth (RE metal ions. For the 3d transition metals, the 3d electrons are exterior and delocalized; leading to strong direct exchange interactions and high Curie temperatures, but often the orbital momentum is zero, leading to small total magnetic moments per atom. In RE metals, the 4f electrons are localized, exchange interactions are indirect, via 5d or 6s conduction electrons, but the high orbital momentum is leading to high total magnetic moments per atom, like 3.27μB for Nd. The Curie point for Nd is 19 K. In this paper we present the results of our study on ZnO films doped with Nd. Hall measurements are performed to investigate the electrical properties of films. Here we prepared and investigated ZnO films doped with different concentration of Nd. The films are grown on a-plane Al2O3 or SiO2 substrates. Hall investigations of electrical properties revealed the presence of a degenerate, highly conducting, film–substrate interface layer for the films grown on Al2O3; such an effect can be avoided, for example, by using SiO2 substrates. Magnetotransport measurements indicated no anomalous Hall effect, but a pronounced negative magneto resistance ratio that can be interpreted as a paramagnetic response of the system to the applied magnetic field. We would like to proceed with the surface sensitive techniques for investigating magnetic properties of ZnO:RE thin films.

  12. Green coloration of Co-doped ZnO explained from structural refinement and bond considerations.

    Science.gov (United States)

    Gaudon, M; Toulemonde, O; Demourgues, A

    2007-12-24

    ZnO doped with Co2+ has been prepared by a Pechini process and investigated in terms of crystallographic structure and UV-visible properties. We emphasize for the first time a splitting of the ZnO band gap in two "sub-band gaps" (never clearly mentioned until now) which is fully interpreted basing on the iono-covalent nature of the O-Zn bonds. An anticipative approach of the potential structure relaxations was discussed from exchanged effective charge per bond calculated with the purely ionic Brown and Altermatt model.

  13. Many-body electronic structure calculations of Eu-doped ZnO

    Science.gov (United States)

    Lorke, M.; Frauenheim, T.; da Rosa, A. L.

    2016-03-01

    The formation energies and electronic structure of europium-doped zinc oxide has been determined using DFT and many-body G W methods. In the absence of intrisic defects, we find that the europium-f states are located in the ZnO band gap with europium possessing a formal charge of 2+. On the other hand, the presence of intrinsic defects in ZnO allows intraband f -f transitions otherwise forbidden in atomic europium. This result corroborates with recently observed photoluminescence in the visible red region S. Geburt et al. [Nano Lett. 14, 4523 (2014), 10.1021/nl5015553].

  14. Research Update: Doping ZnO and TiO2 for solar cells

    Directory of Open Access Journals (Sweden)

    Robert L. Z. Hoye

    2013-12-01

    Full Text Available ZnO and TiO2 are two of the most commonly used n-type metal oxide semiconductors in new generation solar cells due to their abundance, low-cost, and stability. ZnO and TiO2 can be used as active layers, photoanodes, buffer layers, transparent conducting oxides, hole-blocking layers, and intermediate layers. Doping is essential to tailor the materials properties for each application. The dopants used and their impact in solar cells are reviewed. In addition, the advantages, disadvantages, and commercial potential of the various fabrication methods of these oxides are presented.

  15. Electrical and mechanical properties of ZnO doped silver-molybdate glass-nanocomposite system

    Science.gov (United States)

    Kundu, Ranadip; Roy, Debasish; Bhattacharya, Sanjib

    2016-05-01

    Zno doped silver-molybdate glass-nanocomposites, 0.3 Ag2O - 0.7 [0.075 ZnO - 0.925 MoO3] have been prepared by melt-quenching method. Ionic conductivity of these glass-nanocomposites has been measured in wide temperature and frequency windows. Vicker's hardness methods have been employed to study micro-hardness of the as-prepared samples. Heat-treated counterparts for this glass-nanocomposites system has been analyzed in different temperature to observe the changes in conductivity as well as micro-hardness for that system.

  16. Turn-off of fluorescence of styryl phenanthrimidazole on doping ZnO nanoparticles with Ce(3+).

    Science.gov (United States)

    Jayabharathi, J; JebaSingh, I; Arunpandiyan, A; Karunakaran, C

    2015-01-25

    ZnO nanoparticles were doped with Ce(3+) by sol-gel synthesis and characterized by high-resolution scanning electron microscopy (HR-SEM), powder X-ray diffraction (XRD) and UV-visible diffuse reflectance (DRS) and photoluminescence (PL) spectroscopies. The dynamics of photoinduced electron injection from styryl phenanthrimidazole to Ce(3+)-doped ZnO nanoparticles has been studied by absorption, fluorescence and lifetime spectroscopic methods. Both the absorption and fluorescence quenching results suggest association between Ce(3+)-doped ZnO and the phenanthrimidazole. The free energy change (ΔGet) for electron injection has been calculated. The critical energy transfer distance between the phenanthrimidazole and Ce(3+)-doped ZnO nanoparticles has been deduced. In contrast to our earlier observation of enhancement of fluorescence of the phenanthrimidazole by ZnO nanoparticles, doping ZnO with Ce(3+) turns off its fluorescence. These findings provide a method to test the presence of Ce(3+) in ZnO nanocrystals. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Photoluminescence on cerium-doped ZnO nanorods produced under sequential atomic layer deposition-hydrothermal processes

    Science.gov (United States)

    Cervantes-López, J. L.; Rangel, R.; Espino, J.; Martínez, E.; García-Gutiérrez, R.; Bartolo-Pérez, P.; Alvarado-Gil, J. J.; Contreras, O. E.

    2017-01-01

    Doped and undoped ZnO nanorod arrays were produced combining atomic layer deposition and hydrothermal processes. First, a ZnO layer with preferential orientation normal to the c-axis was grown on the substrate by means of the decomposition of diethylzinc; subsequently, the nanorod arrays were produced through solvothermal process using a solution of Zn(NO3)2 as precursor. Doped ZnO nanorods were produced using Ce(C2H3O2)3·H2O as dopant agent precursor. Undoped and Ce-doped ZnO nanorod arrays showed high-intensity photoluminescence. The doping concentration of x = 0.04 (Zn1- x Ce x O) displayed the highest photoluminescence. Undoped ZnO showed an intense UV peak centered at 382 nm with a narrow full wide half maximum of 33 nm. Ce-doped ZnO PL spectra contain three bands, one signal in the UV region centered at 382 nm, other centered at 467 nm in the near-green region and other one emission centered at 560 nm. The results herein exposed demonstrate the capability to produce high-quality ZnO and Zn1- x Ce x O films.

  18. Photorefractive Effect of a Liquid Crystal Cell with a ZnO Nanorod Doped in Only One PVA Layer

    Institute of Scientific and Technical Information of China (English)

    GUO Yu-Bing; CHEN Yong-Hai; XIANG Ying; QU Sheng-Chun; WANG Zhan-Guo

    2011-01-01

    We observe obviously different diffraction efficiencies with forward and reverse dc voltages in a forced-light-scattering (FLS) experiment for a cell with ZnO nanorod doped in only one poly (vinyl alcohol) (PVA) layer. When a dc voltage with a positive pole on the ZnO nanorod doped side is applied, the excited charge carriers primarily move along the transverse direction, which results in a higher diffraction efficiency. Conversely, when the dc voltage with a negative pole on the ZnO nanorod doped side is applied, the excited charge carriers primarily move along the longitudinal direction, which leads to a lower diffraction efficiency. A largest diffraction efficiency of about 9% is achieved in the ZnO nanorod doped liquid crystal cell.%@@ We observe obviously different diffraction efficiencies with forward and reverse do voltages in a forced-light-scattering(FLS)experiment for a cell with ZnO nanorod doped in only one poly(vinyl alcohol)(PVA)layer.When a do voltage with a positive pole on the ZnO nanorod doped side is applied,the excited charge carriers primarily move along the transverse direction,which results in a higher diffraction efficiency.Conversely,when the do voltage with a negative pole on the ZnO nanorod doped side is applied,the excited charge carriers primarily move along the longitudinal direction,which leads to a lower diffraction efficiency.A largest diffraction efficiency of about 9%is achieved in the ZnO nanorod doped liquid crystal cell.

  19. Band gap engineering and enhanced photoluminescence of Mg doped ZnO nanoparticles synthesized by wet chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Arshad, Mohd; Meenhaz Ansari, Mohd [Department of Applied Physics, Aligarh Muslim University, Aligarh (India); Ahmed, Arham S. [Department of Physics, Aligarh Muslim University, Aligarh (India); Tripathi, Pushpendra [Department of Applied Physics, Aligarh Muslim University, Aligarh (India); Ashraf, S.S.Z. [Department of Physics, Aligarh Muslim University, Aligarh (India); Naqvi, A.H. [Department of Applied Physics, Aligarh Muslim University, Aligarh (India); Azam, Ameer, E-mail: azam222@rediffmail.com [Department of Applied Physics, Aligarh Muslim University, Aligarh (India)

    2015-05-15

    In the present investigations Mg doped ZnO nanoparticles were synthesized using sol–gel method. Mg doping in nanoparticles was found to be a good method for tuning of band gap and photoluminescence of ZnO nanoparticles. Simultaneously, Mg doping also inhibited the growth of particle size and it decreased from 36.1 to 13.5 nm with the increase in doping concentration from 0% to 12%. Optical band gap was found to increase from 3.23 to 3.47 eV and photoluminescence studies revealed that visible PL emission was enhanced with doping concentration. - Highlights: • Significant decrease in particle size with Mg doping. • Increase in band gap with Mg doping. • Enhanced luminescence as a result of Mg doping.

  20. Comparison of two innovative precipitation systems for ZnO and Al-doped ZnO nanoparticle synthesis

    Directory of Open Access Journals (Sweden)

    Anne Aimable

    2010-09-01

    Full Text Available This study presents a comparative approach to investigate the potentials of two innovative methods for the synthesis of ZnO and Al-doped ZnO. The first method is a precipitation system working in mild hydrothermal conditions (90°C using a tubular reactor (Segmented Flow Tubular Reactor, SFTR. The second method is a microwave-assisted hydrothermal process working at 250°C - 38 atmospheres. Nanocrystalline ZnO with a high specific surface area (49–68 m2/g was obtained with both systems. Smaller equiaxed particles (50–70 nm were obtained with the SFTR, with an excellent homogeneity in size and morphology, which was attributed to an excellent control of the process parameters (mixing, temperature, volume of reaction. A higher luminescence signal was measured on these samples. The microwave method leads to particles with a higher crystallinity due to the temperature of the reaction. A significant effect of the aluminum was observed, which reduces the crystal growth to produce equiaxed morphologies. This effect was enhanced by adding poly(acrylic acid (PAA.

  1. Comparative studies of Al-doped ZnO and Ga-doped ZnO transparent conducting oxide thin films

    OpenAIRE

    Jun, Min-Chul; Park, Sang-Uk; Koh, Jung-Hyuk

    2012-01-01

    We have investigated the influences of aluminum and gallium dopants (0 to 2.0 mol%) on zinc oxide (ZnO) thin films regarding crystallization and electrical and optical properties for application in transparent conducting oxide devices. Al- and Ga-doped ZnO thin films were deposited on glass substrates (corning 1737) by sol–gel spin-coating process. As a starting material, AlCl3⋅6H2O, Ga(NO3)2, and Zn(CH3COO)2⋅2H2O were used. A lowest sheet resistance of 3.3 × 103 Ω/□ was obtained for the GZO ...

  2. Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

    KAUST Repository

    Maller, Robert

    2016-05-24

    The measured structural, optical and electrical properties of Al, Ga and In doped ZnO films deposited using spray pyrolysis are reported over the doping range 0.1 - 3 atomic percent (at. %). Over the entire doping series highly transparent, polycrystalline thin films are prepared. Using the AC Hall effect we probe the electronic properties of our doped films separating the impact of doping on the measured charge carrier concentrations and Hall mobility, with an emphasis on the low doping, < 1 at. %, range. In this doping range highly resistive films are formed and we highlight AC Hall as a reliable and highly reproducible technique for analysing the doping mechanism. The implementation of a simple, post-deposition heat treatment of our AZO films creates typical films with charge carrier concentrations exceeding > 1019 cm-3 and electron mobilities over 10 cm2/Vs. We describe in detail the nature of the defect chemistry and the role of intrinsic defects, particularly traps, and show that despite significant variations in dopant species and grain boundary concentrations that the defect chemistry dominates the electrical characteristics.

  3. Effects of Fe fine powders doping on hot deformed NdFeB magnets

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Min, E-mail: linm@nimte.ac.cn [Ningbo Institute of Material Technology & Engineering Chinese Academy of Science, Ningbo 315201 (China); Wang, Huijie [Ningbo Jinji Strong Magnetic Material Company, Ningbo 315041 (China); Zheng, Jingwu [Zhejiang University of Technology, Hangzhou 310014 (China); Yan, Aru [Ningbo Institute of Material Technology & Engineering Chinese Academy of Science, Ningbo 315201 (China)

    2015-04-01

    The composite NdFeB magnets with blending melt-spun flakes and Fe fine powders were prepared by the hot-pressed and hot-deformed route. Characterizations of the hot-deformed NdFeB magnets affected by the doped Fe powders were tested. The doped Fe powders decrease the hot-deformed pressure when the strain is between 15 and 50%. XRD patterns show that the doped Fe powders have little influence on the c-axis alignment of hot-deformed NdFeB magnets in the press direction. The B{sub r} and the (BH){sub max} get improved when the doped Fe powders are less than 3 wt%. The doped Fe of hot-deformed NdFeB magnets exists in the elongated state and the spherical state surrounded by the Nd-rich phase. With the Fe fraction increasing, the potential of magnet moves to the positive direction and the diameter of the Nyquist arc becomes larger, which indicate that the corrosion resistance improved effectively. The bending strength was enhanced by the elongated α-Fe phase embedded in the matrix 2:14:1 phase. - Highlights: • The doped Fe powders have little influence on the c-axis alignment of magnets. • The elongated Fe powders are more than the spherical Fe powders in the magnets. • The corrosion resistance is improved effectively with the increasing Fe fraction. • The bending strength is enhanced by the elongated α-Fe phase embedded in the matrix.

  4. XPS studies and photocurrent applications of alkali-metals-doped ZnO nanoparticles under visible illumination conditions

    Science.gov (United States)

    Saáedi, Abdolhossein; Yousefi, Ramin; Jamali-Sheini, Farid; Zak, Ali Khorsand; Cheraghizade, Mohsen; Mahmoudian, M. R.; Baghchesara, Mohammad Amin; Dezaki, Abbas Shirmardi

    2016-05-01

    The present work is a study about a relationship between X-ray photoelectron spectrometer (XPS) results and photocurrent intensity of alkali-metals-elements doped ZnO nanoparticles, which is carried out under visible illumination conditions. The nanoparticles were synthesized by a simple sol-gel method. Structure and morphology studies of the NPs were carried out by X-ray diffraction analysis (XRD) and transmission electron microscopy (TEM). The effect of doping on the optical band-gap was investigated by using UV-visible spectrometer. The absorption peak of the doped ZnO NPs was red-shifted with respect to that of the undoped ZnO NPs. After that, the photocurrent application of the products was examined under a white light source at 2 V bias. The photocurrent results showed that, the current intensity of the ZnO NPs was increased by doping materials. However, K-doped ZnO NPs showed the highest photocurrent intensity. Finally, a discussion was carried out about the obtained photocurrent results by the O-1s spectra of the XPS of the samples. Our results suggest that the alkali-metals-doped ZnO NPs exhibit considerable promise for highly sensitive visible-light photodetectors.

  5. The structural and mechanical behaviours of Boron-doped ZnO nanostructures

    Science.gov (United States)

    Senol, Abdulkadir; Demirozu Senol, Sevim; Ozturk, Ozgur; Asikuzun, Elif; Tasci, Ahmet Tolga; Terzioglu, Cabir

    2015-03-01

    Undoped and Boron (B)-doped Zinc Oxide (ZnO) nanopowders were synthesized by Hydrothermal method. The structural and mechanical behaviours of B doped ZnO (Zn1-xBx O, x =0, 0.05, 0.07, 0.11) were systematically examined. The crystal structure, phases, sizes and microstructure of Zn1-xBx O powder samples characterized by using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). Microhardness values of all B doped ZnO powders were measured with different loads (0.245, 0.490, 0.980, 1.960 ve 2.940 N) using a digital Vickers microhardness tester. The experimental microhardness data were used to determine elastic modules, yield strength, and fracture toughness value of the samples. Additionally, the experimental results were analyzed using the various theoretical models namely, Kick's Law, Elastic/Plastic Deformation (EPD) models, Proportional Specimen Resistance (PSR), and Hays-Kendall (HK) approach. The Vickers microhardness measurements revealed that hardness of Zn1-xBx O powder samples increased with B doping. This research partially supported by Abant Izzet Baysal University Scientific Research Projects Coordination Department under the Grant No. BAP-2013.03.02.609.

  6. Formulation and Characterization of Cu Doped ZnO Thick Films as LPG Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. V. PATIL

    2010-12-01

    Full Text Available Thick films of pure and various concentrations (1 wt. %, 3 wt. %, 5 wt. %, 7 wt. % and 10 wt. % of Cu-doped ZnO were prepared on alumina substrates using a screen printing technique. These films were fired at a temperature of 700ºC for two hours in an air atmosphere. Morphological, compositional and structural properties of the samples were obtained using the scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDAX and X-ray diffraction techniques respectively. The LPG gas sensing properties of these thick films were investigated at different operating temperatures and LPG gas concentrations. The surface resistance of thick films decreases when exposed to LPG gas. The Cu doped films show significant sensitivity to LPG gas than pure ZnO film. 5 wt. % Cu-doped ZnO film was found to be more sensitive (87.3 % to LPG gas exposed at 300 oC than other doping concentrations with fast response and recovery time.

  7. Effect of Sb2O3-doped on optical absorption of ZnO thin film

    Institute of Scientific and Technical Information of China (English)

    CHANG Chun-rong; LI Zi-quan; XU Yun-yun

    2006-01-01

    Sb2O3 doped ZnO thin film was prepared by RF magnetron sputtering technique.The influence of Sb2O3 on the structure and the optical absorption of ZnO thin film was studied by XPS,XRD apparatuses and UV-Vis spectrophotometer.The results show that doped Sb2O3 has affected atomic and electronic structures,growth modes of crystal grains and optical absorption of ZnO.The element Sb exists in many forms in the film including transpositional atoms and compounds such as Sb2O3,Zn7Sb2O14 etc.ZnO crystal grains grow in mixing directions.The lattice relaxation and the content of second phases increase when more Sb is doped.The UVA absorption of doped ZnO thin film increases obviously.The ultraviolet absorption peak narrows,absorption intensity increases,the absorption margin becomes steep and moves to shorter wavelength of about 5 nm,and the visible absorption increases in some sort.

  8. High performance Ce-doped ZnO nanorods for sunlight-driven photocatalysis

    Directory of Open Access Journals (Sweden)

    Bilel Chouchene

    2016-09-01

    Full Text Available Ce-doped ZnO (ZnO:Ce nanorods have been prepared through a solvothermal method and the effects of Ce-doping on the structural, optical and electronic properties of ZnO rods were studied. ZnO:Ce rods were characterized by XRD, SEM, TEM, XPS, BET, DRS and Raman spectroscopy. 5% Ce-doped ZnO rods with an average length of 130 nm and a diameter of 23 nm exhibit the highest photocatalytic activity for the degradation of the Orange II dye under solar light irradiation. The high photocatalytic activity is ascribed to the substantially enhanced light absorption in the visible region, to the high surface area of ZnO:Ce rods and to the effective electron–hole pair separation originating from Ce doping. The influence of various experimental parameters like the pH, the presence of salts and of organic compounds was investigated and no marked detrimental effect on the photocatalytic activity was observed. Finally, recyclability experiments demonstrate that ZnO:Ce rods are a stable solar-light photocatalyst.

  9. High performance Ce-doped ZnO nanorods for sunlight-driven photocatalysis.

    Science.gov (United States)

    Chouchene, Bilel; Ben Chaabane, Tahar; Balan, Lavinia; Girot, Emilien; Mozet, Kevin; Medjahdi, Ghouti; Schneider, Raphaël

    2016-01-01

    Ce-doped ZnO (ZnO:Ce) nanorods have been prepared through a solvothermal method and the effects of Ce-doping on the structural, optical and electronic properties of ZnO rods were studied. ZnO:Ce rods were characterized by XRD, SEM, TEM, XPS, BET, DRS and Raman spectroscopy. 5% Ce-doped ZnO rods with an average length of 130 nm and a diameter of 23 nm exhibit the highest photocatalytic activity for the degradation of the Orange II dye under solar light irradiation. The high photocatalytic activity is ascribed to the substantially enhanced light absorption in the visible region, to the high surface area of ZnO:Ce rods and to the effective electron-hole pair separation originating from Ce doping. The influence of various experimental parameters like the pH, the presence of salts and of organic compounds was investigated and no marked detrimental effect on the photocatalytic activity was observed. Finally, recyclability experiments demonstrate that ZnO:Ce rods are a stable solar-light photocatalyst.

  10. Doping effect on SILAR synthesized crystalline nanostructured Cu-doped ZnO thin films grown on indium tin oxide (ITO) coated glass substrates and its characterization

    Science.gov (United States)

    Dhaygude, H. D.; Shinde, S. K.; Velhal, Ninad B.; Takale, M. V.; Fulari, V. J.

    2016-08-01

    In the present study, a novel chemical route is used to synthesize the undoped and Cu-doped ZnO thin films in aqueous solution by successive ionic layer adsorption and reaction (SILAR) method. The synthesized thin films are characterized by x-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray analysis (EDAX), contact angle goniometer and UV-Vis spectroscopic techniques. XRD study shows that the prepared films are polycrystalline in nature with hexagonal crystal structure. The change in morphology for different doping is observed in the studies of FE-SEM. EDAX spectrum shows that the thin films consist of zinc, copper and oxygen elements. Contact angle goniometer is used to measure the contact angle between a liquid and a solid interface and after detection, the nature of the films is initiated from hydrophobic to hydrophilic. The optical band gap energy for direct allowed transition ranging between 1.60-2.91 eV is observed.

  11. Cu-doped ZnO nanoporous film for improved performance of CdS/CdSe quantum dot-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Myeong-Soo; Son, Min-Kyu; Kim, Soo-Kyoung; Park, Songyi; Prabakar, Kandasamy; Kim, Hee-Je, E-mail: heeje@pusan.ac.kr

    2014-11-03

    Copper (Cu) doped zinc oxide (ZnO) powders were synthesized by co-precipitation method with different at% (0 and 0.5 at%) of Cu dopant. Cu-doped ZnO nanoporous (NP) films were fabricated to enhance the performance of the ZnO based cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dot-sensitized solar cells (QDSSCs). The existence of Cu ions in the Cu-doped ZnO NP film was detected by X-ray fluorescence. The surface morphology, microstructure and crystal structure of Cu-doped ZnO NP films were analyzed by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The optical property of CdS/CdSe co-sensitized Cu-doped ZnO NP film was studied by UV–vis absorption spectroscopy. The photovoltaic performance and electrical property of Cu-doped ZnO CdS/CdSe QDSSCs were studied by current–voltage characteristic curves and electrochemical impedance spectroscopy under air mass 1.5 condition. As a result, short circuit current density and fill factor increased from 9.074 mA/cm{sup 2} and 0.403 to 9.865 mA/cm{sup 2} and 0.427 respectively, based on the enhanced absorbance and electron transport by Cu-doping. This led to the increasing light conversion efficiency from 2.27% to 2.61%. - Highlights: • Cu-doped ZnO powders were synthesized by co-precipitation method. • Cu-doped ZnO nanoporous films with high crystallinity were uniformly deposited. • Absorbance of Cu-doped ZnO nanoporous film was enhanced. • Electron conductivity of Cu-doped ZnO nanoporous film was enhanced. • Performance of Cu-doped ZnO CdS/CdSe QDSSC was improved.

  12. Synthesis and stress relaxation of ZnO/Al-doped ZnO core-shell nanowires.

    Science.gov (United States)

    Wang, Hong-Bo; Ma, Fei; Li, Qian-Qian; Dong, Ce-Zhou; Ma, Da-Yan; Wang, Hong-Tao; Xu, Ke-Wei

    2013-04-07

    Doping nanostructures is an effective method to tune their electrical and photoelectric properties. Taking ZnO nanowires (NWs) as a model system, we demonstrate that atomic layer deposition (ALD) can be adopted for the realization of a doping process by the homo-epitaxial growth of a doped shell on the NW core. The Al-doped ZnO NWs have a layered superlattice structure with dopants mainly occupying the interstitial positions. After annealing, Al(3+) ions diffuse into the ZnO matrix and occupy substitutional locations, which is desirable for dopant activation. The stress accumulated during epitaxial growth is relaxed by the nucleation of dislocations, dislocation dipoles and anti-phase boundaries. We note that the proposed method can be easily adopted for doping different types of nanostructures, and fabricating superlattices and multiple quantum wells on NWs in a controllable way.

  13. Effects of Al Doping on the Properties of ZnO Thin Films Deposited by Atomic Layer Deposition.

    Science.gov (United States)

    Zhai, Chen-Hui; Zhang, Rong-Jun; Chen, Xin; Zheng, Yu-Xiang; Wang, Song-You; Liu, Juan; Dai, Ning; Chen, Liang-Yao

    2016-12-01

    The tuning of structural, optical, and electrical properties of Al-doped ZnO films deposited by atomic layer deposition technique is reported in this work. With the increasing Al doping level, the evolution from (002) to (100) diffraction peaks indicates the change in growth mode of ZnO films. Spectroscopic ellipsometry has been applied to study the thickness, optical constants, and band gap of AZO films. Due to the increasing carrier concentration after Al doping, a blue shift of band gap and absorption edge can be observed, which can be interpreted by Burstein-Moss effect. The carrier concentration and resistivity are found to vary significantly among different doping concentration, and the optimum value is also discussed. The modulations and improvements of properties are important for Al-doped ZnO films to apply as transparent conductor in various applications.

  14. Effects of Al Doping on the Properties of ZnO Thin Films Deposited by Atomic Layer Deposition

    Science.gov (United States)

    Zhai, Chen-Hui; Zhang, Rong-Jun; Chen, Xin; Zheng, Yu-Xiang; Wang, Song-You; Liu, Juan; Dai, Ning; Chen, Liang-Yao

    2016-09-01

    The tuning of structural, optical, and electrical properties of Al-doped ZnO films deposited by atomic layer deposition technique is reported in this work. With the increasing Al doping level, the evolution from (002) to (100) diffraction peaks indicates the change in growth mode of ZnO films. Spectroscopic ellipsometry has been applied to study the thickness, optical constants, and band gap of AZO films. Due to the increasing carrier concentration after Al doping, a blue shift of band gap and absorption edge can be observed, which can be interpreted by Burstein-Moss effect. The carrier concentration and resistivity are found to vary significantly among different doping concentration, and the optimum value is also discussed. The modulations and improvements of properties are important for Al-doped ZnO films to apply as transparent conductor in various applications.

  15. Synthesis and characterization of surfactant assisted Mn2+ doped ZnO nanocrystals

    Directory of Open Access Journals (Sweden)

    N. Shanmugam

    2016-09-01

    Full Text Available We report the synthesis and characterization of Mn doped ZnO nanocrystals, both in the free standing and PVP capped particle forms. The nanocrystals size could be controlled by capping them with polyvinylpyrollidone and was estimated by X-ray diffraction and transmission electron microscopy. The chemical compositions of the products were characterized by FT-IR spectroscopy. UV–Vis absorption spectroscopy measurements reveal that the capping of ZnO leads to blue shift due to quantum confinement effect. The morphology of the particles was evaluated by Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM. Both the Thermo Gravimetric Analysis (TGA and Differential Thermal Analysis (DTA curves of the ZnO show no further weight loss and thermal effect at a temperature above 510 °C.

  16. Enhancement of exciton radiative recombination for In-doped ZnO nanowires with aluminum cylindrical micropillars

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jen-Cheng; Liang, Yu-Ting; Cheng, Fang-Ching; Fang, Chia-Hui; Chen, Hung-Ing; Tsai, Chung-Yuan [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan, ROC (China); Jiang, Joe-Air [Department of Bio-Industrial Mechatronics Engineering, National Taiwan University, Taipei 106, Taiwan, ROC (China); Nee, Tzer-En, E-mail: neete@mail.cgu.edu.tw [Graduate Institute of Electro-Optical Engineering and Department of Electronic Engineering, Chang Gung University, 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan 333, Taiwan, ROC (China)

    2013-04-15

    Zinc oxide (ZnO) has attracted intensive research effort in recent years, due to its unique properties and versatile applications. Recent work on the conservation of surface plasmon (SP) and light through period metal arrays has elucidated the propagation of SP resonance behavior. In this paper, we discuss the enhancement of exciton radiative recombination of the ZnO nanowires with Al cylindrical micropillars. Optical characterization of exciton interacted with SP resonance for indium-doped ZnO nanowires with Al cylindrical micropillars has been also investigated. From photoluminescence spectra of In-doped ZnO nanowires, it is found that the In-doped ZnO nanowires have a blue emission at 425 nm, which resulted from the ZnO band-to-band transition. Prior to the arrays of samples were annealed, a broad green emission centered at 500 nm was observed, which is attributed to ZnO native point defects. The relatively strong green band emission results from the radiative recombination that arises from the ionized oxygen vacancy and surface-defect related luminescence. Compare the In-doped ZnO on Si substrate, the enhancement of PL intensity for In-doped ZnO with deposited Al pattern film can be attributed to strong interaction with SP resonance and exciton over a broad temperature range. These experimental results indicate that Al cylindrical micropillars can significantly enhance carrier confinement and increase the quantum efficiency of In-doped ZnO/Al heterostructures due to the interaction of SP resonance between the In-doped ZnO nanowires and Al cylindrical micropillar structures, the surface-defect related luminescence, and the auxiliary test structures with variable micropillar parameters. -- Highlights: ► We examine the exciton radiative recombination of the ZnO nanowires. ► Al cylindrical micropillars affect the carrier recombination of ZnO/Al structures. ► The interaction of SP resonance between In-doped ZnO nanowire and Al pattern film. ► The carrier

  17. Ba-DOPED ZnO MATERIALS: A DFT SIMULATION TO INVESTIGATE THE DOPING EFFECT ON FERROELECTRICITY

    Directory of Open Access Journals (Sweden)

    Luis H. da S. Lacerda

    2016-04-01

    Full Text Available ZnO is a semiconductor material largely employed in the development of several electronic and optical devices due to its unique electronic, optical, piezo-, ferroelectric and structural properties. This study evaluates the properties of Ba-doped wurtzite-ZnO using quantum mechanical simulations based on the Density Functional Theory (DFT allied to hybrid functional B3LYP. The Ba-doping caused increase in lattice parameters and slight distortions at the unit cell angle in a wurtzite structure. In addition, the doping process presented decrease in the band-gap (Eg at low percentages suggesting band-gap engineering. For low doping amounts, the wavelength characteristic was observed in the visible range; whereas, for middle and high doping amounts, the wavelength belongs to the Ultraviolet range. The Ba atoms also influence the ferroelectric property, which is improved linearly with the doping amount, except for doping at 100% or wurtzite-BaO. The ferroelectric results indicate the ZnO:Ba is an strong option to replace perovskite materials in ferroelectric and flash-type memory devices.

  18. Sn doping induced enhancement in the activity of ZnO nanostructures against antibiotic resistant S. aureus bacteria

    Directory of Open Access Journals (Sweden)

    Jan T

    2013-09-01

    Full Text Available Tariq Jan,1 Javed Iqbal,1 Muhammad Ismail,2 M Zakaullah,3 Sajjad Haider Naqvi,4 Noor Badshah51Laboratory of Nanoscience and Technology, Department of Physics, International Islamic University, Islamabad, Pakistan; 2Institute of Biomedical and Genetic Engineering, Islamabad, Pakistan; 3Department of Physics, Quaid-i-Azam University, Islamabad, Pakistan; 4Department of Biochemistry, University of Karachi, Karachi, Pakistan; 5Department of Basic Science, University of Engineering and Technology, Peshawar, PakistanAbstract: Highly ionic metal oxide nanostructures are attractive, not only for their physiochemical properties but also for antibacterial activity. Zinc oxide (ZnO nanostructures are known to have inhibitory activity against many pathogens but very little is known about doping effects on it. The antibacterial activity of undoped ZnO and tin (Sn doped ZnO nanostructures synthesized by a simple, versatile, and wet chemical technique have been investigated against Escherichia coli, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa bacterial strains. It has been interestingly observed that Sn doping enhanced the inhibitory activity of ZnO against S. aureus more efficiently than the other two bacterial strains. From cytotoxicity and reactive oxygen species (ROS production studies it is found that Sn doping concentration in ZnO does not alter the cytotoxicity and ROS production very much. It has also been observed that undoped and Sn doped ZnO nanostructures are biosafe and biocompatible materials towards SH-SY5Y Cells. The observed behavior of ZnO nanostructures with Sn doping is a new way to prevent bacterial infections of S. aureus, especially on skin, when using these nanostructures in creams or lotions in addition to their sunscreen property as an ultraviolet filter. Structural investigations have confirmed the formation of a single phase wurtzite structure of ZnO. The morphology of ZnO nanostructures is found to vary

  19. Structural characterization and EXAFS wavelet analysis of Yb doped ZnO by wet chemistry route

    Energy Technology Data Exchange (ETDEWEB)

    Otal, Eugenio H., E-mail: eugenio.otal@citedef.gob.ar [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Laboratory for Materials Science and Technology, FRSC-UTN, Av. Inmigrantes 555, Río Gallegos 9400 (Argentina); Sileo, Elsa [INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Aguirre, Myriam H. [Dept. of Physics Condensed Matter, University of Zaragoza (Spain); Laboratory of Advanced Microscopy (LMA), Institute of Nanoscience of Aragón (INA), University of Zaragoza (Spain); Fabregas, Ismael O. [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Kim, Manuela [Division of Porous Materials, UNIDEF, CITEDEF, CONICET, S.J.B de la Salle 4397, Villa Martelli (B1603ALO), Buenos Aires (Argentina); Laboratory for Materials Science and Technology, FRSC-UTN, Av. Inmigrantes 555, Río Gallegos 9400 (Argentina)

    2015-02-15

    Highlights: • Optical and electrical properties of ZnO are influenced by lanthanide doping. • Optical and electrical properties of ZnO are influenced by lanthanide positioning. • Yb is incorporated in the O{sub h} sites of the wurtzite structure. • There is not Yb{sub 2}O{sub 3} clustering or segregation for treatments below 800 °C. - Abstract: Lanthanide doped ZnO are interesting materials for optical and electrical applications. The wide band gap of this semiconductor makes it transparent in the visible range (E{sub gap} = 3.2 eV), allowing a sharp emission from intra shell transition from the lanthanides. From the electrical side, ZnO is a widely used material in varistors and its electrical properties can be tailored by the inclusion of lanthanides. Both applications are influenced by the location of the lanthanides, grain boundaries or lattice inclusion. Yb doped ZnO samples obtained by wet chemistry route were annealed at different temperatures and characterized by Transmission Electron Microscopy (TEM), X-ray Diffraction (XRD), Rietveld refinement of XRD data, and X-ray Absorption Fine Structure (XAFS). These techniques allowed to follow the changes occurred in the matrix and the Yb environment. The use of the Cauchy continuous wavelet transform allowed identifying a second coordination shell composed of Zn atoms, supporting the observations from XRD Rietveld refinement and XAFS fittings. The information obtained confirmed the incorporation of Yb in O{sub h} sites of the wurtzite structure without Yb{sub 2}O{sub 3} clustering in the lattice.

  20. Luminescence properties and decay kinetics of nano ZnO powder doped with cerium ions

    Energy Technology Data Exchange (ETDEWEB)

    Panda, Nihar Ranjan, E-mail: nihar@iitbbs.ac.in [Indian Institute of Technology Bhubaneswar, Bhubaneswar 751013, Orissa (India); Acharya, B.S., E-mail: bsacharya1950@gmail.com [Department of Physics, C.V. Raman College of Engineering, Bhubaneswar 752054, Orissa (India); Singh, Th. Basanta [Luminescence Dating Laboratory, Manipur University, Imphal 795003 (India); Gartia, R.K. [Department of Physics, Manipur University, Imphal 795003 (India)

    2013-04-15

    ZnO nanopowders doped with cerium ions (1.2 and 1.5 at. wt.%) were synthesized through soft solution route using ultrasound. Sonication has been found to be an effective way for doping rare earth ions like cerium into ZnO. This was confirmed from energy dispersive analysis of X-rays (EDAX) measurement. Further, optical absorption and photoluminescence (PL) measurements corroborate this finding. X-ray diffraction (XRD) studies show the increase of crystallite size and unit cell volume with doping of cerium ions. Formation of fibrous structure of ZnO:Ce was observed from the transmission electron microscopy (TEM) measurements. Although the structural measurements indicate Ce{sup 4+} ion occupying substitutional site in ZnO, PL and absorption studies confirmed the presence of Ce{sup 3+} ion in the powder. The coexistence of Ce{sup 3+} and Ce{sup 4+} ions has been explained on the basis of conversion of Ce{sup 3+} to Ce{sup 4+} in the oxidizing environment. Thermoluminescence (TL) and photo-stimulated decay of luminescence (PSDL) decay studies give an idea of various trapping levels present in the band gap of ZnO. These traps release electrons during optical stimulation to give bimolecular kinetics in nano ZnO:Ce powders. -- Highlights: ► Sonication: an effective way of incorporation of cerium ions into ZnO. ► Site dependent characteristic emission of cerium. ► Energy transfer from host lattice to cerium ions. ► Mono and bimolecular kinetics of ZnO:Ce.

  1. On the transparent conducting oxide Al doped ZnO: First Principles and Boltzmann equations study

    Energy Technology Data Exchange (ETDEWEB)

    Slassi, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Naji, S. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Department of Physics, Faculty of Science, Ibb University, Ibb (Yemen); Benyoussef, A. [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco); Hamedoun, M., E-mail: hamedoun@hotmail.com [Institute of Nanomaterials and Nanotechnology, MAScIR, Rabat (Morocco); El Kenz, A. [LMPHE (URAC 12), Faculté des Sciences, Université Mohammed V-Agdal, Rabat (Morocco)

    2014-08-25

    Highlights: • The incorporation of Al in ZnO increases the optical band edge absorption. • Incorporated Al creates shallow donor states of Al-3s around Fermi level. • Transmittance decreases in the visible and IR regions, while it increases in the UV region. • Electrical conductivity increases and reaches almost the saturation for high concentration of Al. - Abstract: We report, in this work, a theoretical study on the electronic, optical and electrical properties of pure and Al doped ZnO with different concentrations. In fact, we investigate these properties using both First Principles calculations within TB-mBJ approximation and Boltzmann equations under the constant relaxation time approximation for charge carriers. It is found out that, the calculated lattice parameters and the optical band gap of pure ZnO are close to the experimental values and in a good agreement with the other theoretical studies. It is also observed that, the incorporations of Al in ZnO increase the optical band edge absorption which leads to a blue shift and no deep impurities levels are induced in the band gap as well. More precisely, these incorporations create shallow donor states around Fermi level in the conduction band minimum from mainly Al-3s orbital. Beside this, it is found that, the transmittance is decreased in the visible and IR regions, while it is significantly improved in UV region. Finally, our calculations show that the electrical conductivity is enhanced as a result of Al doping and it reaches almost the saturation for high concentration of Al. These features make Al doped ZnO a transparent conducting electrode for optoelectronic device applications.

  2. Structural and optical properties of Na doped ZnO nanocrystals: Application to solar photocatalysis

    Science.gov (United States)

    Tabib, Asma; Bouslama, Wiem; Sieber, Brigitte; Addad, Ahmed; Elhouichet, Habib; Férid, Mokhtar; Boukherroub, Rabah

    2017-02-01

    Na doped ZnO nanocrystals (NCs) were successfully produced by sol-gel process and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), Raman scattering, UV-vis diffuse reflectance spectroscopy and photoluminescence (PL). XRD analysis indicated that all the prepared samples present pure hexagonal wurtzite structure without any Na related phases. The lattice distortion, calculated using Williamson hall equation, induces stress and a reduction of NCs size from 71.4 to 24.5 nm. TEM images showed NCs with hexagonal shape and a rather uniform size distribution. The selected area electron diffraction (SAED) patterns confirmed the high crystal quality along the direction and is consistent with the hexagonal wurtzite structure of ZnO. The Raman spectra are dominated by E2high mode of ZnO. High Na doping shows the occurrence of anomalous local vibrational Raman modes close to 270 and 513 cm-1 that are related to intrinsic host lattice defects and distortion, respectively. Optical band gap was found to vary with Na content. Photoluminescence (PL) spectra indicate the presence of a high density of defects in ZnO NCs which are mainly oxygen vacancies. Finally, the obtained NCs were used as a photocatalyst to degrade Rhodamine B (RhB) in solution, under solar irradiation. Na doping enhances the photocatalytic activity of ZnO NCs till an optimum concentration of 0.5% where a full degradation was observed after 120 min of sun light irradiation. Furthermore, this sample presents a good cycling stability and reusability. Based on scavangers test, it was found that both superoxide and hydroxyl oxidizing radicals are mainly actives.

  3. Formation of polar surfaces in microstructured ZnO by doping with Cu and applications in photocatalysis using visible light

    Energy Technology Data Exchange (ETDEWEB)

    Pawar, Rajendra C.; Choi, Da-Hyun; Lee, Jai-Sung; Lee, Caroline S., E-mail: sunyonglee@hanyang.ac.kr

    2015-02-01

    We report the synthesis of copper-doped zinc oxide microstructures with a large amount of polar surfaces using a single-step facile chemical method by collecting powders of zinc oxide (ZnO) microstructures. It was found that rod-like morphology of ZnO transformed into disk and sphere-like structure with nanosheets. Hollow disk-like structures were formed due to the surface etching properties of Cl{sup −} ions in the copper chloride precursor. The photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB) dyes was measured under irradiation with visible light using the structures as catalysts. The Cu-doped ZnO exhibited better photodegradation properties than did undoped ZnO. The enhanced performance is attributed to the existence of (001) polar surfaces, oxygen vacancies, and increased optical absorbance at visible wavelengths, which is consistent with the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), room temperature photoluminescence (PL), and optical absorbance measurements. These favorable photocatalytic properties of the doped microstructures demonstrate their potential for use in wastewater treatment. - Graphical abstract: Graphical abstract shows the electron transfer mechanism under visible light for Cu-doped ZnO microstructures and the photocatalytic degradation of dye. - Highlights: • Cu induced microstructures of ZnO with polar surfaces. • Methylene blue degradation under visible light irradiation. • Room temperature ferromagnetism due to oxygen vacancies in ZnO. • 7% Cu–ZnO has highest photocatalytic activity.

  4. Effect of Sr doping on the electronic band structure and optical properties of ZnO: A first principle calculation

    Science.gov (United States)

    Mahmood, Asad; Tezcan, Fatih; Kardaş, Gülfeza; Karadaǧ, Faruk

    2017-09-01

    Incorporating impurities in ZnO provide opportunities to manipulate its electronic and optical properties, which can be exploited for optoelectronic device applications. Among various elements doped in ZnO crystal structure, limited attempts have been accounted for the Sr-doped ZnO system. Further, no theoretical evidence has been reported so far to explore the Sr-doped ZnO frameworks. Here, we report first principle study for the pure and Sr-doped ZnO (Zn1-xSrxO) structure. We employed the Perdew-Burke-Ernzerhof exchange-correlation function parameters in generalized gradient approximations. In light of these estimations, we calculated the electronic band gap, density of states, and optical parameters, for example, absorption, dielectric functions, reflectivity, refractive index, and energy-loss. The studies suggested that Sr incorporation expanded the optical band gap of ZnO. In addition, the energy-loss significantly increased with Sr content which might be associated with an increase in the degree of disorder in the crystal lattice with Sr incorporation. Also, significant changes were seen in the optical properties of ZnO with Sr content in the low energy region. The theoretical results were likewise compared with the previously reported experimental data.

  5. Preparation of Al-doped ZnO films by aqueous solution process using a continuous circulation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Miyake, Masao; Fukui, Hiroshi; Hirato, Tetsuji [Graduate School of Energy, Kyoto University, Yoshida-hommachi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2012-05-15

    The fabrication of Al-doped ZnO films by an aqueous solution process using a continuous circulation reactor was studied. By heating ZnO-saturated ammonia solutions containing 2-10 mM Al(NO{sub 3}){sub 3} with pH 10.7 at 90 C under ambient pressure, polycrystalline ZnO films with Al content of 1-2 at.% were deposited. The carrier concentration of ZnO films increased with increasing Al content, indicating that Al was successfully incorporated into the ZnO crystals. The Al-doped ZnO films had carrier concentrations of 10{sup 19}-10{sup 20} cm{sup -3} and mobilities of 0.7-7 cm{sup 2}/V/s after annealing at 300 C in air. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Synthesis and characterization of nanostructured undoped and Sn-doped ZnO thin films via sol–gel approach

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, H., E-mail: cihataydin_26@hotmail.com [Department of Metallurgical and Materials Engineering, Engineering Faculty, Tunceli University, Tunceli 62000 (Turkey); El-Nasser, H.M. [Department of Physics, Al al-Bayt University, Mafraq (Jordan); Aydin, C. [Department of Metallurgy and Materials Engineering, Faculty of Technology, Firat University, Elazig 23119 (Turkey); Al-Ghamdi, Ahmed A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Yakuphanoglu, F. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Department of Physics, Faculty of Science, Firat University, Elazig 23119 (Turkey); Nanoscience and Nanotechnology Laboratory, Firat University, Elazig 23119 (Turkey)

    2015-09-30

    Graphical abstract: - Highlights: • Sn-doped ZnO films were prepared via facile sol–gel spin coating method. • The grain size of the films changes from 39.23 to 71.84 nm with Sn doping. • The refractive index dispersion of the films obeys the single oscillator model. - Abstract: Thin films of Sn-doped ZnO were prepared via facile sol–gel spin coating method. The structural and optical properties of the films were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV-VIS-NIR spectrophotometer. The X-ray results confirmed that all the ZnO thin films are polycrystalline with a hexagonal wurtzite structure with a preferential orientation of (002) plane. The crystallite size and lattice parameter values of the films were obtained. Atomic force microscopy results indicate that the Sn-doped ZnO films have the nanostructure. The grain size values of the films were found to vary from 39.23 to 71.84 nm with Sn doping. The nanostructure of the Sn-doped ZnO films was also confirmed by scanning electron microcopy. The optical bandgaps of the films were calculated for the various Sn contents. The refractive index dispersion curves obey the single oscillator model. The optical constants and dispersion parameters of the ZnO films were changed with Sn doping. The obtained results suggest that the structural and optical properties of ZnO films can be controlled by Sn doping.

  7. Effect of Mn doping on structural and optical properties of sol gel derived ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Husain, Shahid, E-mail: s.husain@lycos.com [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Alkhtaby, Lila A. [Department of Physics, Aligarh Muslim University, Aligarh 202002 (India); Giorgetti, Emilia [Istituto dei Sistemi Complessi ISC-CNR Sezione di Firenze, Sesto Fiorentino 50019, Firenze (Italy); Zoppi, Angela; Muniz Miranda, Maurizio [Department of Chemistry, University of Firenze, Sesto Fiorentino 50019, Firenze (Italy)

    2014-01-15

    We have synthesized the Zn{sub 1−x} Mn{sub x} O (x=0.01, 0.02, 0.03 and 0.05) nanoparticles by the sol–gel method. These samples are characterized using x-ray diffraction (XRD), Scanning Electron Microscope (SEM), Ultraviolet/Visible (UV/Vis) spectroscopy, Fluorescence spectroscopy, Raman spectroscopy and Fourier transform infra red (FTIR) spectroscopy. The x-ray diffraction patterns show that all the samples are formed in single phase with a complete solubility of Mn ions in the ZnO matrix. SEM micrographs show that the Mn doped ZnO nanoparticles are hexagonal with wurtzite structure.The particle sizes range between 18 and 35 nm. We have observed a decrease in fluorescence intensity on Mn doping and all the Mn doped samples show lower value of intensity as compared to pure ZnO in the visible range of spectrum. Raman spectroscopy reveals that the characteristic intense band of ZnO at 435 cm{sup −1} exhibits a decrease in intensity and slightly red shifts for 5% Mn doping. FTIR spectra exhibit additional bands on Mn doping as compared to pure ZnO. -- Highlights: • Mn doped ZnO nanoparticels are synthesized through sol gel process. • All the samples show wurtzite crystal symmetry with particle sizes which are found to be in the range from 18 to 35 nm. • The energy band-gap estimated using UV/Vis spectra is found to increase with the Mn doping. • Raman spectra reveal that characteristic intense band of ZnO at 436 cm{sup −1} exhibit a decrease in intensity but peak position does not shift with Mn doping.

  8. Structural, morphological, optical and opto-thermal properties of Ni-doped ZnO thin films using spray pyrolysis chemical technique

    Indian Academy of Sciences (India)

    S Rajeh; A Barhoumi; A Mhamdi; G Leroy; B Duponchel; M Amlouk; S Guermazi

    2016-02-01

    Nickel-doped zinc oxide thin films (ZnO : Ni) at different percentages were deposited on glass substrates using a chemical spray technique. The effect of Ni concentration on the structural, morphological, optical and photoluminescence (PL) properties of the ZnO : Ni thin films were investigated. X-ray diffraction analysis revealed that all films consist of single phase ZnO and was well crystallized in würtzite phase with the crystallites preferentially oriented towards the (002) direction parallel to the c-axis. The optical transmittance measurement was found to be higher than 90%, the optical band gap values of ZnO thin films decreased after doping from 3.29 to 3.21 eV. A noticeable change in optical constants was observed between undoped and Ni-doped ZnO. Room-temperature PL is observed for ZnO, and Ni-doped ZnO thin films.

  9. Effects of annealing on the ferromagnetism and photoluminescence of Cu-doped ZnO nanowires

    Science.gov (United States)

    Xu, H. J.; Zhu, H. C.; Shan, X. D.; Liu, Y. X.; Gao, J. Y.; Zhang, X. Z.; Zhang, J. M.; Wang, P. W.; Hou, Y. M.; Yu, D. P.

    2010-01-01

    Room temperature ferromagnetic Cu-doped ZnO nanowires have been synthesized using the chemical vapor deposition method. By combining structural characterizations and comparative annealing experiments, it has been found that both extrinsic (CuO nanoparticles) and intrinsic (Zn1-xCuxO nanowires) sources are responsible for the observed ferromagnetic ordering of the as-grown samples. As regards the former, annealing in Zn vapor led to a dramatic decrease of the ferromagnetism. For the latter, a reversible switching of the ferromagnetism was observed with sequential annealings in Zn vapor and oxygen ambience respectively, which agreed well with previous reports for Cu-doped ZnO films. In addition, we have for the first time observed low temperature photoluminescence changed with magnetic properties upon annealing in different conditions, which revealed the crucial role played by interstitial zinc in directly mediating high Tc ferromagnetism and indirectly modulating the Cu-related structured green emission via different charge transfer transitions.

  10. Phase Pure Synthesis and Morphology Dependent Magnetization in Mn Doped ZnO Nanostructures

    Directory of Open Access Journals (Sweden)

    Murtaza Saleem

    2014-01-01

    Full Text Available Zn0.95Mn0.05O nanostructures were synthesized using sol gel derived autocombustion technique. As-burnt samples were thermally annealed at different temperatures (400, 600, and 800°C for 8 hours to investigate their effect on structural morphology and magnetic behavior. X-ray diffraction and scanning electron microscopic studies demonstrated the improvement in crystallinity of phase pure wurtzite structure of Mn doped ZnO with variation of annealing temperature. Energy dispersive X-ray elemental compositional analysis confirmed the exact nominal compositions of the reactants. Electrical resistivity measurements were performed with variation in temperature, which depicted the semiconducting nature similar to parent ZnO after 5 at% Mn doping. Magnetic measurements by superconducting quantum interference device detected an enhanced trend of ferromagnetic interactions in thermally annealed compositions attributed to the improved structural morphology and crystalline refinement process.

  11. Progress in ZnO Acceptor Doping: What Is the Best Strategy?

    Directory of Open Access Journals (Sweden)

    Judith G. Reynolds

    2014-01-01

    Full Text Available This paper reviews the recent progress in acceptor doping of ZnO that has been achieved with a focus toward the optimum strategy. There are three main approaches for generating p-type ZnO: substitutional group IA elements on a zinc site, codoping of donors and acceptors, and substitution of group VA elements on an oxygen site. The relevant issues are whether there is sufficient incorporation of the appropriate dopant impurity species, does it reside on the appropriate lattice site, and lastly whether the acceptor ionization energy is sufficiently small to enable significant p-type conduction at room temperature. The potential of nitrogen doping and formation of the appropriate acceptor complexes is highlighted although theoretical calculations predict that nitrogen on an oxygen site is a deep acceptor. We show that an understanding of the growth and annealing steps to achieve the relevant acceptor defect complexes is crucial to meet requirements.

  12. Monte Carlo simulation of magnetic phase transitions in Mn-doped ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Drissi, L.B., E-mail: ldrissi@ictp.it [INANOTECH, Institute of Nanomaterials and Nanotechnology (MAScIR), Rabat (Morocco); International Centre for Theoretical Physics, ICTP, Trieste (Italy); Benyoussef, A. [INANOTECH, Institute of Nanomaterials and Nanotechnology (MAScIR), Rabat (Morocco); Laboratoire de Magnetisme et PHE, Faculte des Sciences, Universite Mohammed V, Rabat (Morocco); Saidi, E.H. [INANOTECH, Institute of Nanomaterials and Nanotechnology (MAScIR), Rabat (Morocco); LPHE, Modelisation et Simulation, Faculte des Sciences, Universite Mohammed V, Rabat (Morocco); CPM, Centre of Physics and Mathematics-Rabat (Morocco); Bousmina, M. [INANOTECH, Institute of Nanomaterials and Nanotechnology (MAScIR), Rabat (Morocco)

    2011-12-15

    The magnetic properties of Mn-doped ZnO semiconductor have been investigated using the Monte Carlo method within the Ising model. The temperature dependences of the spontaneous magnetization, specific heat and magnetic susceptibility have been constructed for different concentrations of magnetic dopant Mn and different carrier concentrations. The exact values of Mn concentration and carrier concentration at which high temperature transition occurs are determined. An alternative for the explanation of some controversies concerning the existence and the nature of magnetism in Mn diluted in ZnO systems is given. Other features are also studied. - Highlights: > Mn-doped ZnO is well investigated by ab-initio, but we are not aware of any studies using Monte Carlo. > We aim to shed more light on ambiguities concerning reports of ferromagnetism in ZnO diluted by Mn. > We use MC that gives more precise results than effective field theory that over estimates T{sub Curie}. > We study the effect of magnetic impurities and hole carriers on the existence and nature of ferromagnetism. > We give the exact values of carriers' concentration that perform magnetic order and those to avoid.

  13. Growth and characterization of ZnO nanorod arrays on boron-doped diamond films by low temperature hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gao Shiyong, E-mail: gaoshiyong@gmail.com [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Li Dongmei; Li Yingai; Lv Xianyi [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Wang Jinzhong; Li Hongtao; Yu Qingjiang; Guo Fengyun; Zhao Liancheng [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer Large-scale ZnO nanorods arrays were grown on boron-doped diamond films. Black-Right-Pointing-Pointer The growth behavior of ZnO nanorods is independent of diamond facets. Black-Right-Pointing-Pointer ZnO nanorods show good optical properties and crystal quality. - Abstract: A facile hydrothermal method has been developed to grow large-scale ZnO nanorods arrays (NRs) on boron-doped diamond (BDD) films at a low temperature of 95 Degree-Sign C. The ZnO nanorods with average diameter of 200 nm are single-crystal hexagonal structure and grow along the [0 0 1] direction. The thin ZnO film plays a key role in driving the nucleation and growth of the ZnO NRs on BDD films. It has been demonstrated that the ZnO nanorods are grown vertically on diamond facets, and this growth behavior is independent of types of diamond facets. The growth mechanism and room temperature photoluminescence (PL) properties of ZnO NRs are investigated.

  14. Effect of seed layer on the self assembly of spray pyrolyzed Al-doped ZnO nanoparticles

    Directory of Open Access Journals (Sweden)

    Charu Dwivedi

    2013-03-01

    Full Text Available Al-doped ZnO (AlZO nanorod arrays and nanostructures were fabricated on seed coated glass substrates via CoSP (Continuous Spray Pyrolysis reactor. The as-synthesized aluminium doped ZnO nanoparticles and nanorods were analyzed through different characterization techniques. There were no significant changes found in the structure with doping of Al but the morphology of the film changed to branched nanorods and nanosheets with the change in seed solution and annealing temperature, respectively. Also, the current–voltage curves of the ZnO and AZO nanorod arrays was measured and it was found that the current response of AZO nanorods was higher than that of ZnO nanorods, proving the Al incorporation as a dopant.

  15. High sensitivity ethanol gas sensor based on Sn - doped ZnO under visible light irradiation at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Peishuo; Pan, Guofeng; Zhang, Bingqiang; Zhen, Jiali; Sun, Yicai, E-mail: pgf@hebut.edu.cn [Institute of Microelectronic, Hebei University of Technology, Tianjin (China)

    2014-07-15

    Pure ZnO and 5at%, 7at%, 9at% Sn - doped ZnO materials are prepared by the chemical co - precipitation method. They were annealed by furnace at temperature range of 300 - 700ºC in air for 1h. The ZnO materials are characterized by X - ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that the Sn - doped ZnO materials appear rough porous structures. The maximum sensitivity can be achieved by doping the amount of 7 at%. It has much better sensing performance towards ethanol vapor under visible light irradiation. The response and recovery time are ~1s and ~5s, respectively. The mechanism for the improvement in the sensing properties can be explained with the surface adsorption theory and the photoactivation theory. (author)

  16. Optical and magnetic properties of Yb ion-doped cobalt-based ZnO nanoparticles for DMS applications

    Indian Academy of Sciences (India)

    T Thangeeswari; M Priya; J Velmurugan; N Padmanathan

    2015-09-01

    Well-crystalline structured ZnO nanoparticles with cobalt (Co) and ytterbium (Yb) multiple ions doping were successfully synthesized by the chemical precipitation technique. The structures, optical and magnetic properties of the samples were analysed with X-ray diffraction (XRD), UV–visible spectroscopy and magnetic measurements, respectively. In the XRD pattern of the pure ZnO and Yb co-doped samples, the formation of highly crystalline phase of pure ZnO was observed even at high Yb concentration. UV–vis spectra show a strong UV absorbance for all the samples with different absorbance maxima. Magnetic characterizations have shown that the sample with 1% Yb co-doped ZnO: Co nanoparticles exhibited a clear ferromagnetic (FM) behaviour at room temperature. The X-ray photoelectron spectral peaks for Yb 4f ions reveal Yb occupation of both Yb3+ as well as Yb2+ states. Hence, it can be confirmed that a clear FM behaviour at room temperature was exhibited by an imbalanced valence state of Yb that strongly interacted with the Co2+. When compared to the Co-doped ZnO, Yb co-doped ZnO exhibits a clear ferromagnetism at room temperature with high coercivity due to the contribution of both 3d and 4f exchange interaction with the host matrix.

  17. Annealed Ce{sup 3+}-doped ZnO flower-like morphology synthesized by chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Koao, Lehlohonolo F., E-mail: koaolf@ufs.ac.za [Department of Physics, University of the Free State (Qwa Qwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, Francis B.; Tsega, Moges [Department of Physics, University of the Free State (Qwa Qwa campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, Hendrik C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2016-01-01

    We have successfully synthesized ZnO:xmol% Ce{sup 3+} (0≤x≤10 mol%) doped nanopowders via the chemical bath deposition method (CBD) technique at low temperature (80 °C) and annealed in air at 700 °C. The X-ray diffraction patterns showed that all the undoped and Ce-doped ZnO nanopowders have a hexagonal wurtzite polycrystalline structure with an average crystallite size of about 46 nm. Weak diffraction peaks related mainly to cerium oxide were also detected at higher concentrations of Ce{sup 3+} (x=5–10 mol%). The scanning electron microscopy study revealed that the nanopowder samples were assembled in flower-shaped undoped ZnO and pyramid-shaped Ce{sup 3+}-doped ZnO nanostructures. The UV–vis spectra showed that the absorption edges shifted slightly to the longer wavelengths with the increase in the Ce{sup 3+} ions concentration. Moreover, the photoluminescence (PL) results showed a relative weak visible emission for the Ce{sup 3+}-doped ZnO nanoparticles compared to the undoped ZnO. The effects of Ce{sup 3+}-doping on the structure and PL of ZnO nanopowders are discussed in detail.

  18. Room temperature enhanced red emission from novel Eu{sup 3+} doped ZnO nanocrystals uniformly dispersed in nanofibers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yongzhe; Wang Qijie [School of Electrical and Electronic Engineering and School of Physical and Mathematical Sciences, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore); Liu Yanxia; Li Xiaodong; Xie Erqing, E-mail: QJWANG@ntu.edu.sg [School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000 (China)

    2011-10-14

    Achieving red emission from ZnO-based materials has long been a goal for researchers in order to realize, for instance, full-color display panels and solid-state light-emitting devices. However, the current technique using Eu{sup 3+} doped ZnO for red emission generation has a significant drawback in that the energy transfer from ZnO to Eu{sup 3+} is inefficient, resulting in a low intensity red emission. In this paper, we report an efficient energy transfer scheme for enhanced red emission from Eu{sup 3+} doped ZnO nanocrystals by fabricating polymer nanofibers embedded with Eu{sup 3+} doped ZnO nanocrystals to facilitate the energy transfer. In the fabrication, ZnO nanocrystals are uniformly dispersed in polymer nanofibers prepared by the high electrical field electrospinning technique. Enhanced red emission without defect radiation from the ZnO matrix is observed. Three physical mechanisms for this observation are provided and explained, namely a small ZnO crystal size, uniformity distribution of ZnO nanocrystals in polymers (PVA in this case), and strong bonding between ZnO and polymer through the -OH group bonding. These explanations are supported by high resolution transmission emission microscopy measurements, resonant Raman scattering characterizations, photoluminescence spectra and photoluminescence excitation spectra measurements. In addition, two models exploring the 'accumulation layer' and 'depletion layer' are developed to explain the reasons for the more efficient energy transfer in our ZnO nanocrystal system compared to that in the previous reports. This study provides an important approach to achieve enhanced energy transfer from nanocrystals to ions which could be widely adopted in rare earth ion doped materials. These discoveries also provide more insights into other energy transfer problems in, for example, dye-sensitized solar cells and quantum dot solar cells.

  19. Room temperature enhanced red emission from novel Eu3 + doped ZnO nanocrystals uniformly dispersed in nanofibers

    Science.gov (United States)

    Zhang, Yongzhe; Liu, Yanxia; Li, Xiaodong; Jie Wang, Qi; Xie, Erqing

    2011-10-01

    Achieving red emission from ZnO-based materials has long been a goal for researchers in order to realize, for instance, full-color display panels and solid-state light-emitting devices. However, the current technique using Eu3 + doped ZnO for red emission generation has a significant drawback in that the energy transfer from ZnO to Eu3 + is inefficient, resulting in a low intensity red emission. In this paper, we report an efficient energy transfer scheme for enhanced red emission from Eu3 + doped ZnO nanocrystals by fabricating polymer nanofibers embedded with Eu3 + doped ZnO nanocrystals to facilitate the energy transfer. In the fabrication, ZnO nanocrystals are uniformly dispersed in polymer nanofibers prepared by the high electrical field electrospinning technique. Enhanced red emission without defect radiation from the ZnO matrix is observed. Three physical mechanisms for this observation are provided and explained, namely a small ZnO crystal size, uniformity distribution of ZnO nanocrystals in polymers (PVA in this case), and strong bonding between ZnO and polymer through the -OH group bonding. These explanations are supported by high resolution transmission emission microscopy measurements, resonant Raman scattering characterizations, photoluminescence spectra and photoluminescence excitation spectra measurements. In addition, two models exploring the 'accumulation layer' and 'depletion layer' are developed to explain the reasons for the more efficient energy transfer in our ZnO nanocrystal system compared to that in the previous reports. This study provides an important approach to achieve enhanced energy transfer from nanocrystals to ions which could be widely adopted in rare earth ion doped materials. These discoveries also provide more insights into other energy transfer problems in, for example, dye-sensitized solar cells and quantum dot solar cells.

  20. First-principles study and electronic structures of Mn-doped ultrathin ZnO nanofilms

    Institute of Scientific and Technical Information of China (English)

    E. Salmani; A. Benyoussef; H. Ez-Zahraouy; E. H. Saidi; O. Mounkachi

    2012-01-01

    The first-principles density functional calculation is used to investigate the electronic structures and magnetic properties of Mn-doped and N-co-doped ZnO nanofilms.The band structure calculation shows that the band gaps of ZnO films with 2,4,and 6 layers are larger than the band gap of the bulk with wurtzite structure and decrease with the increase of film thickness.However,the four-layer ZnO nanofilms exhibit ferromagnetic phases for Mn concentrations less than 24% and 12% for Mn-doping performed in the whole layers and two layers of the film respectively,while they exhibit spin glass phases for higher Mn concentrations.It is also found,on the one hand,that the spin glass phase turns into the ferromagnetic one,with the substitution of nitrogen atoms for oxygen atoms,for nitrogen concentrations higher than 16% and 5% for Mn-doping performed in the whole layers and two layers of the film respectively.On the other hand,the spin-glass state is more stable for ZnO bulk containing 5% of Mn impurities,while the ferromagnetic phase is stable by introducing the p-type carriers into the bulk system.Moreover,it is shown that using the effective field theory for ferromagnetic system,the Curie temperature is close to the room temperature for the undamped Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction.

  1. Al doped ZnO thin films - microstructure, physical and sensor properties

    Science.gov (United States)

    Starbov, N.; Balabanov, S.; Bineva, I.; Rachkova, A.; Krumov, E.; Starbova, K.

    2012-12-01

    Thin ZnO films doped with Al are deposited by spray pyrolysis onto glass substrates using starting solution of Zn-acetate + n.AlCl (where 0.1 detection of noxious gases is checked via resistivity measurements under saturated vapours of ethanol, acetone, ammonia, dimethylamine and formalin at room temperature. Finally the results obtained are discussed concerning the application of the ZnO:Al films studied in the field of sensor technique.

  2. Study on synthesis and optical properties of Al-doped ZnO hierarchical nanostructures

    OpenAIRE

    2011-01-01

    Highly densified Al-doped ZnO (denoted as Al-ZnO) hierarchical nanostructures were synthesized on transparent quartz substrate by chemical vapor deposition. It is found that the heating temperature plays a key role on controlling the morphologies of the Al-ZnO hierarchical nanostructures through a temperature dependent migration of Al atoms. Such uneven distribution of Al element in the hierarchical nanostructures is clearly evidenced by the x-ray photoelectron spectrum (XPS) measurements. Th...

  3. Cr-N CO-DOPED ZnO NANOPARTICLES: SYNTHESIS ...

    African Journals Online (AJOL)

    BCSE

    Here we report the synthesis of CrN co-doped ZnO for the first time. ... detoxification of organic dye effluents have taken an increasingly important ... the transition pH range 1.2-2.8, 7.8-9.8 is red to yellow and yellow to blue, respectively. ... 0.1 g of the photocatalyst was dispersed in 50 mL of deionized .... 54 cm-1 are due.

  4. Heteroepitaxial Growth and Doping of ZnO for Optoelectronic Applications

    Science.gov (United States)

    2005-08-19

    nanostructures using several growth proceses , and p-doping 1) chemical solution based synthesis, 2) rf sputtering, 3) pulse and laser deposition (PLD), 4...was refluxed at 1100 C for about half an hour. Part of the solution was heated to make the powder and other part was used for thin films deposition by... parts of the dielectric constants measured on ZnO and ZnCoO films were consistent with the values measured by other methods in literature, indicating

  5. Highly Branched Sn-Doped ZnO Nanostructures for Sunlight Driven Photocatalytic Reactions

    Directory of Open Access Journals (Sweden)

    Yangyang Liu

    2014-01-01

    Full Text Available Ultralong, highly branched Sn-doped zinc oxide (ZnO nanostructures were fabricated using a simple substrate-free chemical vapor deposition (CVD method. The nanostructures exhibited efficient photocatalytic activities in degradation of methylene blue (MB under natural sunlight. 100% of MB with the concentration of 10 mg/L could be completely removed within 36 minutes. Possible reasons for the enhanced photocatalytic effect were analyzed.

  6. Highly Branched Sn-Doped ZnO Nanostructures for Sunlight Driven Photocatalytic Reactions

    OpenAIRE

    2014-01-01

    Ultralong, highly branched Sn-doped zinc oxide (ZnO) nanostructures were fabricated using a simple substrate-free chemical vapor deposition (CVD) method. The nanostructures exhibited efficient photocatalytic activities in degradation of methylene blue (MB) under natural sunlight. 100% of MB with the concentration of 10 mg/L could be completely removed within 36 minutes. Possible reasons for the enhanced photocatalytic effect were analyzed.

  7. Are Fe and Co implanted ZnO and III-nitride semiconductors magnetic?

    CERN Document Server

    AUTHOR|(CDS)2081284; Bharuth-Ram, Krish

    The chemical nature, lattice site locations and magnetic behaviour of Fe and/or Co ions implanted in nitrides (GaN, AlN, and InN) and in ZnO have been investigated using Mössbauer spectroscopy and vibrating sample magnetometer (VSM) techniques. Mössbauer data on nitride and $^{56}$Fe pre-implanted ZnO samples were obtained from emission Mössbauer spectroscopy (eMS) measurements at the ISOLDE facility, CERN, following the implantation of radioactive $^{57}$Mn$^{*}$ which $\\beta$$^{-}$decays to the 14.4 keV Mössbauer state of $^{57}$Fe. In addition, conversion electron Mössbauer spectroscopy (CEMS) data were collected on ZnO single crystals co-implanted with $^{57}$Fe + $^{56}$Fe and $^{57}$Fe + $^{59}$Co ions in a box profile. Emission Mössbauer spectra obtained for GaN and AlN reveal magnetic structure in the ‘wings’ assigned to high spin Fe$^{3+}$ weakly coupled to the lattice showing spin-lattice relaxation effects. The observed spin-relaxation rate (τ$^{-1}$) closely follows a ${T}^{2}$ temperat...

  8. Origin of carrier scattering in polycrystalline Al-doped ZnO films

    Science.gov (United States)

    Jia, Junjun; Oka, Nobuto; Kusayanagi, Minehide; Nakatomi, Satoshi; Shigesato, Yuzo

    2014-10-01

    We observed the carrier transport phenomena in polycrystalline Al-doped ZnO (AZO) films with carrier densities ranging from 2.0 × 1019 to 1.1 × 1021 cm-3. A comparison of the optical carrier density and Hall carrier density indicates that the conduction band in AZO films is nonparabolic above 2.0 × 1020 cm-3. A transition from grain boundary scattering to ionized impurity scattering is observed at a doping level of ˜4.0 × 1020 cm-3. The trap density at the grain boundary increases with increasing Al concentration in the films, implying that the doping level plays a decisive role in the trap density. The excellent fitting of the optical mobility and carrier density using the Brooks-Herring model shows that the acceptor concentration increases with increasing doping level.

  9. Al-doped ZnO Thin Films for Ethanol Sensors

    Science.gov (United States)

    Nulhakim, Lukman; Nugraha; Nuruddin, Ahmad; Suyatman; Yuliarto, Brian

    2011-12-01

    Al doped ZnO (AZO) is done to understand the effect of Al dopant on ZnO. The sensor response condition will be analyzed for ethanol detection. Chemical Bath Deposition (CBD) method is used to fabrication pure ZnO and AZO thin films. Al dopant concentrations used in this study is 2.9 at% Al. The crystallinity, composition and morphology were investigated by using XRD, EDS and SEM. The ZnO and AZO gas sensors were exposed to different concentrations of ethanol at room temperature, 2.5%, 5% and 7.5% volume ethanol, respectively. The sensor response at low concentrations (2.5% V) for pure ZnO sample is 70.88% and 88.57% for high concentrations of ethanol (7.5% V). The highest sensor response for AZO sample is 95.29% at low concentrations (2.5% V) and 96.68% V at the high concentration (7.5% V).

  10. Ferromagnetic Ni-doped ZnO nanoparticles synthesized by a chemical precursor method

    Directory of Open Access Journals (Sweden)

    Jeevan Jadhav

    2013-06-01

    Full Text Available A simple chemical synthesis method of pristine ZnO and Ni-doped ZnO (NixZn1-xO; x = 0.01-0.05 nanoparticles is reported. Structural and morphological properties of the synthesized nanoparticles have been studied using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, vibrating sample magnetometer (VSM, and high-resolution transmission electron microscopy (HRTEM. Average crystallite size calculated from XRD peak widths using Debye Scherrer’s formula comes out to be 12 nm, 8 nm and 10 nm in pristine ZnO, Ni0.01Zn0.99O, and Ni0.05Zn0.95O samples, respectively. HRTEM images clearly show high crystalline order in the derived nanoparticles with particle size of 15-18 nm, which are in good agreement with the XRD results. Magnetic measurements reveal that the incorporation of Ni2+ cations into the ZnO lattice results in induced room-temperature ferromagnetism in the otherwise non-magnetic ZnO.

  11. Synthesis and characterization of ZnO-TiO2 nanopowders doped with fe via sol-gel method and their application in photocatalytic degradation of anionic surfactant

    Science.gov (United States)

    Giahi, M.; Saadat Niavol, S.; Taghavi, H.; Meskinfam, M.

    2015-12-01

    ZnO and 0, 5, and 10 mol % Fe-doped ZnO-TiO2 nanopowders were synthesized by the sol-gel Pechini method. The successful synthesis of coupled ZnO-TiO2 nanopowders was evident by XRD. Scanning electron microscopy (SEM) revealed that the Fe ions were well incorporated into the ZnO-TiO2 crystal lattice. The photocatalytic degradation of anionic surfactant (linear alkylbenzene sulfonate (LABS), was investigated in aqueous solution using ZnO and Fe-doped ZnO-TiO2 nanoparticles. The degradation was studied under different conditions such as the Fe3+ concentration, amount of photocatalyst, irradiation time, pH, initial concentration and presence of electron acceptor. The results showed that photocatalytic degradation of LABS was strongly influenced by these parameters. The best conditions for the photocatalytic degradation of LABS were obtained. It is found that under UV light irradiation, Fe-doping of ZnO-TiO2 increases the efficiency of its photocatalytic activity in degradation of LABS than pure ZnO and ZnO-TiO2.

  12. Tapered Optical Fiber Humidity Sensor Coated with Nano-crystalline ZnO Doped with KCI

    Directory of Open Access Journals (Sweden)

    Sivacoumar Rajalingam

    2015-03-01

    Full Text Available In this research study we have targeted to fabricate a tapered optical fiber coated with zinc oxide doped with KCl to improve the humidity sensing capability of zinc oxide. The optical fiber was tapered through chemical etching method by HF acid (49.5%. The nano-crystalline Zinc Oxide (ZnO was synthesized using single molecular precursor method doped with KCl. The resulting material was characterized with Fourier Transform Infrared spectroscopy (FTIR, X-Ray Diffractometry (XRD and Scanning Electron Microscopy (SEM. The sensing mechanism of this sensor is based on the change of the optical properties of the coating when the relative humidity increases. The humidity sensing characteristic has been estimated by measuring the Optical Permeability (OP as a function of percentage of Relative Humidity (%RH in the ranging from 5 to 98% inside a closed chamber. The tapered optical fiber tested with an overlay coating at the optimal working point achieves better sensitivity. The experimental results show that the 5.7 wt% KCl doped ZnO nano-fibers hold super-rapid response and recovery than normal ZnO coating.

  13. Ferromagnetism in Gd doped ZnO nanowires: A first principles study

    KAUST Repository

    Aravindh, S. Assa

    2014-12-19

    In several experimental studies, room temperature ferromagnetism in Gd-doped ZnO nanostructures has been achieved. However, the mechanism and the origin of the ferromagnetism remain controversial. We investigate the structural, magnetic, and electronic properties of Zn 48O48 nanowires doped with Gd, using density functional theory. Our findings indicate that substitutionally incorporated Gd atoms prefer occupying the surface Zn sites. Moreover, the formation energy increases with the distance between Gd atoms, signifying that no Gd-Gd segregation occurs in the nanowires within the concentration limit of ≤2%. Gd induces ferromagnetism in ZnO nanowires with magnetic coupling energy up to 21 meV in the neutral state, which increases with additional electron and O vacancy, revealing the role of carriers in magnetic exchange. The potential for achieving room temperature ferromagnetism and high TC in ZnO:Gd nanowires is evident from the large ferromagnetic coupling energy (200 meV) obtained with the O vacancy. Density of states shows that Fermi level overlaps with Gd f states with the introduction of O vacancy, indicating the possibility of s-f coupling. These results will assist in understanding experimental findings in Gd-doped ZnO nanowires.

  14. Magnetic Properties of Gadolinium-Doped ZnO Films and Nanostructures

    KAUST Repository

    Roqan, Iman S.

    2016-08-29

    The magnetic properties of Gd-doped ZnO films and nanostructures are important to the development of next-generation spintronic devices. Here, we elucidate the significant role played by Gd-oxygen-deficiency defects in mediating/inducing ferromagnetic coupling in in situ Gd-doped ZnO thin films deposited at low oxygen pressure by pulsed laser deposition (PLD). Samples deposited at higher oxygen pressures exhibited diamagnetic responses. Vacuum annealing was used on these diamagnetic samples (grown at a relatively high oxygen pressures) to create oxygen- deficiency defects with the aim of demonstrating reproducibility of room-temperature ferromagnetism (RTFM). Samples annealed at oxygen environment exhibited super‐ paramagnetism and blocking-temperature effects. The samples possessed secondary phases; Gd segregation led to superparamagnetism. Theoretical studies showed a shift of the 4f level of Gd to the conduction band minimum (CBM) in Gd-doped ZnO nanowires, which led to an overlap with the Fermi level, resulting in strong exchange coupling and consequently RTFM.

  15. Observation of low field microwave absorption in co-doped ZnO system

    Science.gov (United States)

    Mahule, Tebogo S.; Srinivasu, Vijaya V.; Das, Jayashree

    2016-10-01

    Room temperature low field microwave absorption (LFMA) in magnetic materials find application in microwave absorbers and low field sensors. However not all the magnetic materials show LFMA and the phenomenon is not fully understood. We report on the observation of low field microwave absorption (LFMA) or the non-resonant microwave absorption (NRMA) in the transition metal (TM) co-doped ZnO samples of the composition Zn1-x(TM:TM)xO synthesized by solid state reaction technique. LFMA peaks and hysteresis matches very well with that of the magnetization hysteresis loop and the anisotropy fields at room temperature similar to the reports in the literature for other magnetic systems. However we show through our careful experiments that such a correlation between LFMA and the magnetization does not survive at low temperatures and particularly at 10 K the LFMA hysteresis collapses in our TM co-doped ZnO system; whereas the magnetization hysteresis loop becomes very big and anisotropy field becomes bigger in the range of kOe. We interpret the LFMA as field dependent surface impedance or eddy current losses, in terms of a possible role of anomalous hall resistivity that follows magnetization and the ordinary hall resistivity that only follows the applied field. We then argue that LFMA accordingly follows magnetization or applied field when AHE or OHE dominates respectively. Also we confirm the absence of LFMA signals in the rare earth co-doped ZnO system.

  16. Ethanol gas sensing properties of Al2O3-doped ZnO thick film resistors

    Indian Academy of Sciences (India)

    D R Patil; L A Patil; D P Amalnerkar

    2007-12-01

    The characterization and ethanol gas sensing properties of pure and doped ZnO thick films were investigated. Thick films of pure zinc oxide were prepared by the screen printing technique. Pure zinc oxide was almost insensitive to ethanol. Thick films of Al2O3 (1 wt%) doped ZnO were observed to be highly sensitive to ethanol vapours at 300°C. Aluminium oxide grains dispersed around ZnO grains would result into the barrier height among the grains. Upon exposure of ethanol vapours, the barrier height would decrease greatly leading to drastic increase in conductance. It is reported that the surface misfits, calcination temperature and operating temperature can affect the microstructure and gas sensing performance of the sensor. The efforts are, therefore, made to create surface misfits by doping Al2O3 into zinc oxide and to study the sensing performance. The quick response and fast recovery are the main features of this sensor. The effects of microstructure and additive concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of ethanol vapours were studied and discussed.

  17. Structural; morphological; optical and magnetic properties of Mn doped ferromagnetic ZnO thin film

    Science.gov (United States)

    Karmakar, R.; Neogi, S. K.; Banerjee, Aritra; Bandyopadhyay, S.

    2012-12-01

    The structural, optical and magnetic properties of the Zn1-xMnxO (0 disorder developed in the samples due to Mn doping. The films are of single phase in nature; no formation of any secondary phase has been detected from structural analysis. Absence of magnetic impurity phase in these films has been confirmed from morphological study also. Increasing tendency of lattice parameters and unit cell volume has been observed with increasing Mn doping concentration. The incorporation of Mn2+ ions introduces disorder in the system. That also leads to slight degradation in crystalline quality of the films with increasing doping. The grain size reduces with increase in Mn doping proportion. The band gaps shows red shift with doping and the width of localized states shows an increasing tendency with doping concentration. It is due to the formation of impurity band and trapping of Mn atoms, which leads to the generation of the defect states within the forbidden band. Photoluminescence (PL) spectra show gradual decrease of intensity of exitonic and defect related peaks with increasing Mn doping. Defect mediated intrinsic ferromagnetism has been observed even at room temperature for 5 at% Mn doped ZnO film. The strong presence of antiferromagnetic (AFM) interaction reduces the observed ferromagnetic moments.

  18. Superconductivity in Co-doped SmFeAsO

    Energy Technology Data Exchange (ETDEWEB)

    Qi Yanpeng; Gao Zhaoshun; Wang Lei; Wang Dongliang; Zhang Xianping; Ma Yanwei [Key Laboratory of Applied Superconductivity, Institute of Electrical Engineering, Chinese Academy of Sciences, PO Box 2703, Beijing 100190 (China)], E-mail: ywma@mail.iee.ac.cn

    2008-11-15

    Here we report the synthesis and characterizations of SmFe{sub 1-x}Co{sub x}AsO (x = 0.10, 0.15) for the first time. The parent compound SmFeAsO itself is not superconducting but shows an antiferromagnetic order near 150 K, which must be suppressed by doping before superconductivity emerges. With Co doping in the FeAs planes, antiferromagnetic order is destroyed and superconductivity occurs at 15.2 K. Similar to LaFe{sub 1-x}Co{sub x}AsO, the SmFe{sub 1-x}Co{sub x}AsO system appears to tolerate considerable disorder in the FeAs planes. This result is important, suggesting a different mechanism for cuprate superconductors compared to the iron-based arsenide ones.

  19. The structural and electrical properties of Ga-doped ZnO and Ga, B-codoped ZnO thin films: The effects of additional boron impurity

    Energy Technology Data Exchange (ETDEWEB)

    Abduev, Aslan Kh.; Akhmedov, Akmed K.; Asvarov, Abil Sh. [Institute of Physics, DSC of RAS, Yaragskogo Street, 94, Makhachkala 367003 (Russian Federation)

    2007-02-15

    Transparent conducting films of Ga-doped ZnO (GZO) and Ga-, B-codoped ZnO (GZOB) were deposited by dc magnetron sputtering. The dependence of the electrical and structural properties on the type of doping (Ga-doping or Ga-, B-codoping) and substrate temperature were investigated. Microstructural analysis suggests that the substrate temperature and the type of doping modify the microstructure and surface morphology of thin films. GZOB films grown at 200{sup o}C showed a dense structure without columns, a low-resistivity value of 4.2x10{sup -4}{omega}cm, and a visible transmission of 90% with a thickness of 200nm. In addition, the thermal stability of resistivity of GZOB films was greater than one of GZO films. (author)

  20. Mg doping induced high structural quality of sol–gel ZnO nanocrystals: Application in photocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Abed, Chayma; Bouzidi, Chaker [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, BP 95, Hammam-Lif 2050 (Tunisia); Elhouichet, Habib, E-mail: Habib.elhouichet@fst.rnu.tn [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, BP 95, Hammam-Lif 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université Tunis El Manar, Tunis 2092 (Tunisia); Gelloz, Bernard [Graduate School of Engineering, Nagoya University, 2-24-16 Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Ferid, Mokhtar [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des Matériaux, BP 95, Hammam-Lif 2050 (Tunisia)

    2015-09-15

    Highlights: • ZnO nancrystals doped with Mg were prepared from sol–gel method. • Structural and optical properties of ZnO:Mg nanocrystals were investigated. • Good crystalline quality of ZnO nanocrystals was reported after Mg doping. • Good photocatalytic activity of Mg doped ZnO nanocrystals was demonstrated under sun light illumination. - Abstract: Undoped and Mg doped ZnO nanocrystals (NCs) ZnO:x%Mg (x = 1, 2, 3, and 5) were synthesized using sol–gel method. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectivity, and photoluminescence (PL). XRD analysis demonstrates that all prepared samples present pure hexagonal wurtzite structure without any Mg related phases. The NCs size varies from 26.82 nm to 42.96 nm with Mg concentrations; it presents an optimal value for 2% of Mg. The Raman spectra are dominated by the E{sub 2high} mode. For highly Mg doping (5%), the occurrence of silent B{sub 1(low)} mode suggested that the Mg ions do substitute at Zn sites in the ZnO lattice The band gap energy was estimated from both Tauc and Urbach methods and found to be 3.39 eV for ZnO:2%Mg. The PL spectra exhibit two emission bands in the UV and visible range. Their evolution with Mg doping reveals the reduction of defect density in ZnO at low Mg doping by filling Zn vacancies. In addition, it was found that further Mg doping, above 2%, improves the photocatalytic activity of ZnO NCs for photodegradation of Rhodamine B (RhB) under sunlight irradiation. The efficient electron–hole separation is the main factor responsible for the enhancement of photocatalytic performance of Mg doped ZnO NCs. Through this work, we show that by varying the Mg contents in ZnO, this material can be a potential candidate for both optoelectronic and photocatalytic applications.

  1. Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation.

    Science.gov (United States)

    Maleki, Afshin; Safari, Mahdi; Shahmoradi, Behzad; Zandsalimi, Yahya; Daraei, Hiua; Gharibi, Fardin

    2015-11-01

    In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2%) observed using 1.5% Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation.

  2. Comparative studies of Al-doped ZnO and Ga-doped ZnO transparent conducting oxide thin films.

    Science.gov (United States)

    Jun, Min-Chul; Park, Sang-Uk; Koh, Jung-Hyuk

    2012-11-22

    We have investigated the influences of aluminum and gallium dopants (0 to 2.0 mol%) on zinc oxide (ZnO) thin films regarding crystallization and electrical and optical properties for application in transparent conducting oxide devices. Al- and Ga-doped ZnO thin films were deposited on glass substrates (corning 1737) by sol-gel spin-coating process. As a starting material, AlCl3⋅6H2O, Ga(NO3)2, and Zn(CH3COO)2⋅2H2O were used. A lowest sheet resistance of 3.3 × 103 Ω/□ was obtained for the GZO thin film doped with 1.5 mol% of Ga after post-annealing at 650°C for 60 min in air. All the films showed more than 85% transparency in the visible region. We have studied the structural and microstructural properties as a function of Al and Ga concentrations through X-ray diffraction and scanning electron microscopy analysis. In addition, the optical bandgap and photoluminescence were estimated.

  3. Influence of Al-doped ZnO and Ga-doped ZnO substrates on third harmonic generation of gold nanoparticles

    Science.gov (United States)

    Kityk, I. V.; AlZayed, N. S.; Kobayashi, Kei; Chen, Xiaomei; Oyama, Munetaka; El-Naggar, A. M.; Albassam, A. A.

    2015-07-01

    Principal role of substrate types on the nonlinear optical properties of Au NP was investigated. Third harmonic generation (THG) studies were carried out for Au NP deposited on the Al-doped ZnO (AuNP/AZO) and Ga-doped ZnO (AuNP/GZO) substrates at fundamental wavelength of 20 ns Er:glass laser (generating at 1540 nm wavelength) during photostimulation by the 532 nm 15 ns laser pulses. Sizes of Au NP were 5 nm, 10 nm, 20 nm, and 30 nm. The output signal was registered at 513 nm. The photoinduced power density was increased from 0 up to 800 MW/cm2. So in our work we explore the role of the substrate on the optically stimulated non-linear optical properties during simultaneous photo stimulation near the inter-band transition. The results were studied depending on the type of substrate and the sizes of the deposited nanoparticles. The analysis was done within a framework of interaction between the photoinduced light and SPR wavelengths. Control of the photoinduced temperature was done.

  4. Structural and Magnetic Properties of Mn doped ZnO Thin Film Deposited by Pulsed Laser Deposition

    KAUST Repository

    Baras, Abdulaziz

    2011-07-01

    Diluted magnetic oxide (DMO) research is a growing field of interdisciplinary study like spintronic devices and medical imaging. A definite agreement among researchers concerning the origin of ferromagnetism in DMO has yet to be reached. This thesis presents a study on the structural and magnetic properties of DMO thin films. It attempts to contribute to the understanding of ferromagnetism (FM) origin in DMO. Pure ZnO and Mn doped ZnO thin films have been deposited by pulsed laser deposition (PLD) using different deposition conditions. This was conducted in order to correlate the change between structural and magnetic properties. Structural properties of the films were characterized using x-ray diffraction (XRD) and scanning electron microscopy (SEM). The superconducting quantum interference device (SQUID) was used to investigate the magnetic properties of these films. The structural characterizations showed that the quality of pure ZnO and Mn doped ZnO films increased as oxygen pressure (PO) increased during deposition. All samples were insulators. In Mn doped films, Mn concentration decreased as PO increased. The Mn doped ZnO samples were deposited at 600˚C and oxygen pressure from 50-500mTorr. All Mn doped films displayed room temperature ferromagnetism (RTFM). However, at 5 K a superparamagnetic (SPM) behavior was observed in these samples. This result was accounted for by the supposition that there were secondary phase(s) causing the superparamagnetic behavior. Our findings hope to strengthen existing research on DMO origins and suggest that secondary phases are the core components that suppress the ferromagnetism. Although RTFM and SPM at low temperature has been observed in other systems (e.g., Co doped ZnO), we are the first to report this behavior in Mn doped ZnO. Future research might extend the characterization and exploration of ferromagnetism in this system.

  5. Transmission electron microscopy of solution-processed, intrinsic and Al-doped ZnO nanowires for transparent electrode fabrication.

    Science.gov (United States)

    Kusinski, G J; Jokisaari, J R; Noriega, R; Goris, L; Donovan, M; Salleo, A

    2010-03-01

    A solution-based chemistry was used to synthesize intrinsic and Al-doped (1% and 5% nominal atomic concentration of Al) ZnO nanostructures. The nanowires were grown at 300 degrees C in trioctylamine by dissolving Zn acetate and Al acetate. Different doping conditions gave rise to different nanoscale morphologies. The effect of a surfactant (oleic acid) was also investigated. An electron microscopy study correlating morphology, aspect ratio and doping of the individual ZnO wires to the electrical properties of the spin coated films is presented. HRTEM revealed single crystalline [0001] wires.

  6. 过渡金属掺杂ZnO纳米光催化剂对四环素的光催化降解%Effects of transition metal doping on the ZnO photocatalytic degradation of the tetracycline

    Institute of Scientific and Technical Information of China (English)

    关卫省; 宋优男; 霍鹏伟; 杨莉

    2012-01-01

    The article is intended to introduce our work on preparing the Fe-doped, Co-doped, and other similar-doped photocatalysts via a hydrothermal synthesis method as well as the effect of transition metal doped on the ZnO Photocatalytic degradation of the tetracy-cline. Considering the above said research needs, we have characterized the products concerned by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) , and ultraviolet and visible diffusion reflectance spectra (UV - Vis DRS) . It is also from our research needs that we have evaluated the photocatalytic degradation activities of the antibiotics by using catalysts we have developed under the sunlight and under a xenon lamp (A = 250 - 800 nm) irradiation. We have investigated the effects of the above mentioned transition metals, their concentrations, and the ratio of the two metals in co-doped ZnO samples on the photocatalytic efficiency. The results of our investigation and analysis have shown that the products prepared are all hexagonal wurtzite in structure of ZnO, whose crystallization tends to decrease with the increase of the transition metal ions doping concentration. We have also found that under the single transition metal ion doped, Co doping and Ni doping tend to defect the photocatalytic activity of ZnO. However, the photocatalytic activity of Fe-doped ZnO photocatalysi samples can thus be greatly improved. To be exact, when the doping concentration is kept at 7%, the Fe/ZnO sample would like to exhibit the highest photocatalytic degradation rate. In addition, the UV - Vis results show that the absorbance spectra of ZnO tends to have a red shift with doping ol Fe, whose range tends to extend with the increase of Fe doping concentration. Moreover, the photocatalytie performance of Fe - Co co-doped and Fe - Ni co-doped ZnO samples proves to be better than that of Fe doped ZnO, with the photocatalytie activity of 3% Fe - 1% Ni/ZnO being highest. Furthermore, the photocatalytic degradation

  7. Enhanced Photoluminescence and Raman Properties of Al-Doped ZnO Nanostructures Prepared Using Thermal Chemical Vapor Deposition of Methanol Assisted with Heated Brass

    Science.gov (United States)

    Thandavan, Tamil Many K.; Gani, Siti Meriam Abdul; San Wong, Chiow; Md. Nor, Roslan

    2015-01-01

    Vapor phase transport (VPT) assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn) was used to prepare un-doped and Al-doped zinc oxide (ZnO) nanostructures (NSs). The structure and morphology were characterized by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). Photoluminescence (PL) properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni), oxygen interstitials (Oi), zinc vacancy (Vzn), singly charged zinc vacancy (VZn-), oxygen vacancy (Vo), singly charged oxygen vacancy (Vo+) and oxygen anti-site defects (OZn) in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE) and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs. PMID:25756598

  8. Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

    Directory of Open Access Journals (Sweden)

    Tamil Many K Thandavan

    Full Text Available Vapor phase transport (VPT assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn was used to prepare un-doped and Al-doped zinc oxide (ZnO nanostructures (NSs. The structure and morphology were characterized by field emission scanning electron microscopy (FESEM and x-ray diffraction (XRD. Photoluminescence (PL properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni, oxygen interstitials (Oi, zinc vacancy (Vzn, singly charged zinc vacancy (VZn-, oxygen vacancy (Vo, singly charged oxygen vacancy (Vo+ and oxygen anti-site defects (OZn in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

  9. Enhanced photoluminescence and Raman properties of Al-Doped ZnO nanostructures prepared using thermal chemical vapor deposition of methanol assisted with heated brass.

    Science.gov (United States)

    Thandavan, Tamil Many K; Gani, Siti Meriam Abdul; San Wong, Chiow; Md Nor, Roslan

    2015-01-01

    Vapor phase transport (VPT) assisted by mixture of methanol and acetone via thermal evaporation of brass (CuZn) was used to prepare un-doped and Al-doped zinc oxide (ZnO) nanostructures (NSs). The structure and morphology were characterized by field emission scanning electron microscopy (FESEM) and x-ray diffraction (XRD). Photoluminescence (PL) properties of un-doped and Al-doped ZnO showed significant changes in the optical properties providing evidence for several types of defects such as zinc interstitials (Zni), oxygen interstitials (Oi), zinc vacancy (Vzn), singly charged zinc vacancy (VZn-), oxygen vacancy (Vo), singly charged oxygen vacancy (Vo+) and oxygen anti-site defects (OZn) in the grown NSs. The Al-doped ZnO NSs have exhibited shifted PL peaks at near band edge (NBE) and red luminescence compared to the un-doped ZnO. The Raman scattering results provided evidence of Al doping into the ZnO NSs due to peak shift from 145 cm-1 to an anomalous peak at 138 cm-1. Presence of enhanced Raman signal at around 274 and 743 cm-1 further confirmed Al in ZnO NSs. The enhanced D and G band in all Al-doped ZnO NSs shows possible functionalization and doping process in ZnO NSs.

  10. Effect of doping on structural and optical properties of ZnO nanoparticles: study of antibacterial properties

    Science.gov (United States)

    Maddahi, P.; Shahtahmasebi, N.; Kompany, A.; Mashreghi, M.; Safaee, S.; Roozban, F.

    2014-06-01

    Sol-gel method was successfully used for synthesis of ZnO nanoparticles doped with 10 % Mg or Cu. The structure, morphology and optical properties of the prepared nanoparticles were studied as a function of doping content. The synthesized ZnO:(Mg/Cu) samples were characterized using XRD, TEM, FTIR and UV-Vis spectroscopy techniques. The samples show hexagonal wurtzite structure, and the phase segregation takes place for Cu doping. Optical studies revealed that Mg doping increases the energy band gap while Cu incorporation results in decrease of the band gap. The antibacterial activities of the nanoparticles were tested against Escherichia coli (Gram negative bacteria) cultures. It was found that both pure and doped ZnO nanosuspensions show good antibacterial activity which increases with copper doping, and slightly decreases with adding Mg.

  11. Tailoring Energy Bandgap of Al Doped ZnO Thin Films Grown by Vacuum Thermal Evaporation Method.

    Science.gov (United States)

    Vyas, Sumit; Singh, Shaivalini; Chakrabarti, P

    2015-12-01

    The paper presents the results of our experimental investigation pertaining to tailoring of energy bandgap and other associated characteristics of undoped and Al doped ZnO (AZO) thin film by varying the atomic concentration of Al in ZnO. Thin films of ZnO and ZnO doped with Al (1, 3, and 5 atomic percent (at.%)) were deposited on silicon substrate for structural characterization and on glass substrate for optical characterization. The dependence of structural and optical properties of Al doped ZnO on the atomic concentration of Al added to ZnO has been reported. On the basis of the experimental results an empirical formula has been proposed to calculate the energy bandgap of AZO theoretically in the range of 1 to 5 at.% of Al. The study revealed that AZO films are composed of smaller and larger number of grains as compared to pure ZnO counterpart and density of the grains was found to increase as the Al concentration increased (from 1 to 5 at.%). The transmittance in the visible region was greater than 90% and found to increase with increasing Al concentration up to 5 at.%. The optical bandgap was found to increase initially with increase in atomic concentration of Al concentration up to 3 at.% and decrease thereafter with increasing concentration of Al.

  12. Boron doped nanostructure ZnO films deposited by ultrasonic spray pyrolysis

    Science.gov (United States)

    Karakaya, Seniye; Ozbas, Omer

    2015-02-01

    ZnO is an II-VI compound semiconductor with a wide direct band gap of 3.3 eV at room temperature. Doped with group III elements (B, Al or Ga), it becomes an attractive candidate to replace tin oxide (SnO2) or indium tin oxide (ITO) as transparent conducting electrodes in solar cell devices and flat panel display due to competitive electrical and optical properties. In this work, ZnO and boron doped ZnO (ZnO:B) films have been deposited onto glass substrates at 350 ± 5 °C by a cost-efficient ultrasonic spray pyrolysis technique. The optical, structural, morphological and electrical properties of nanostructure undoped and ZnO:B films have been investigated. Electrical resistivity of films has been analyzed by four-probe technique. Optical properties and thicknesses of the films have been examined in the wavelength range 1200-1600 nm by using spectroscopic ellipsometry (SE) measurements. The optical constants (refractive index (n) and extinction coefficient (k)) and the thicknesses of the films have been fitted according to Cauchy model. The optical method has been used to determine the band gap value of the films. Transmission spectra have been taken by UV spectrophotometer. It is found that both ZnO and ZnO:B films have high average optical transmission (≥80%). X-ray diffraction (XRD) patterns indicate that the obtained ZnO has a hexagonal wurtzite type structure. The morphological properties of the films were studied by atomic force microscopy (AFM). The surface morphology of the nanostructure films is found to depend on the concentration of B. As a result, ZnO:B films are promising contender for their potential use as transparent window layer and electrodes in solar cells.

  13. Growth and optical properties of ZnO nanorod arrays on Al-doped ZnO transparent conductive film.

    Science.gov (United States)

    Lin, Suanzhi; Hu, Hailong; Zheng, Weifeng; Qu, Yan; Lai, Fachun

    2013-04-08

    ZnO nanorod arrays (NRAs) on transparent conductive oxide (TCO) films have been grown by a solution-free, catalyst-free, vapor-phase synthesis method at 600°C. TCO films, Al-doped ZnO films, were deposited on quartz substrates by magnetron sputtering. In order to study the effect of the growth duration on the morphological and optical properties of NRAs, the growth duration was changed from 3 to 12 min. The results show that the electrical performance of the TCO films does not degrade after the growth of NRAs and the nanorods are highly crystalline. As the growth duration increases from 3 to 8 min, the diffuse transmittance of the samples decreases, while the total transmittance and UV emission enhance. Two possible nanorod self-attraction models were proposed to interpret the phenomena in the sample with 9-min growth duration. The sample with 8-min growth duration has the highest total transmittance of 87.0%, proper density about 75 μm-2, diameter about 26 nm, and length about 500 nm, indicating that it can be used in hybrid solar cells.

  14. Lanthanum and zirconium co-doped ZnO nanocomposites: synthesis, characterization and study of photocatalytic activity.

    Science.gov (United States)

    Moafi, Hadi Fallah; Zanjanchi, Mohammad Ali; Shojaie, Abdollah Fallah

    2014-09-01

    Nanocomposits of zinc oxide co-doped with lanthanum and zirconium were prepared using the modified sol-gel method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), and BET surface area measurement. For comparison, the La and Zr mono doped ZnO have also been prepared under the same conditions. The XRD results revealed that all the materials showed a hexagonal wurtzite crystal structure. It was found that the particle size of La-Zr-doped ZnO is much smaller as compared to that of pure ZnO. The effect of operational parameters such as, doping concentration, catalyst loading, pH and initial concentration of methylene blue on the extent of degradation was investigated. The photocatalytic activity of the undoped ZnO, mono-doped and La-Zr-ZnO photocatalysts was evaluated by the photocatalytic degradation of methylene blue in aqueous solution. The presence of lanthanium and/or zirconium causes a red shift in the absorption band of ZnO. The results show that the photocatalytic activity of the La-Zr-ZnO photocatalyst is much higher than that of undoped and mono-doped ZnO, resulting from the La and Zr synergistic effect. The co-operation of the lanthanum and zirconium ion leads to the narrowing of the band gap and greatly improves the photocatalytic activity. The photocatalyst co-doped with lanthanum and zirconium 4 mol% shows the best photoactivity and photodecomposition efficiencies were improved by 92% under UV-Vis irradiation at the end of 30 min, compared with the pure and mono doped samples.

  15. An optical study of the D-D neutron irradiation-induced defects in Co-and Cu-doped ZnO wafers

    Institute of Scientific and Technical Information of China (English)

    Wang Yun-Bo; Li Gong-Ping; Xu Nan-Nan; Pan Xiao-Dong

    2013-01-01

    Room-temperature photoluminescence and optical transmittance spectroscopy of Co-doped (1 × 1014,5 × 1016,and 1 × 1017 cm-2) and Cu-doped (5 × 1016 cm-2) ZnO wafers irradiated by D-D neutrons (fluence of 2.9 x 1010 cm-2) have been investigated.After irradiation,the Co or Cu metal and oxide clusters in doped ZnO wafers are dissolved,and the würtzite structure of ZnO substrate for each sample remains unchanged and keeps in high c-axis preferential orientation.The degree of irradiation-induced crystal disorder reflected from the absorption band tail parameter (E0) is far greater for doped ZnO than the undoped one.Under the same doping concentration,the Cu-doped ZnO wafer has much higher irradiation-induced disorder than the Co-doped one.Photoluminescence measurements indicate that the introduction rate of both the zinc vacancy and the zinc interstitial is much higher for the doped ZnO wafer with a high doping level than the undoped one.In addition,both crystal lattice distortion and defect complexes are suggested to be formed in doped ZnO wafers.Consequently,the Co-or Cu-doped ZnO wafer (especially with a high doping level) exhibits very low radiation hardness compared with the undoped one,and the Cu-doped ZnO wafer is much less radiation-hard than the Co-doped one.

  16. ZnO nanowires array grown on Ga-doped ZnO single crystal for dye-sensitized solar cells.

    Science.gov (United States)

    Hu, Qichang; Li, Yafeng; Huang, Feng; Zhang, Zhaojun; Ding, Kai; Wei, Mingdeng; Lin, Zhang

    2015-06-23

    High quality ZnO nanowires arrays were homoepitaxial grown on Ga-doped ZnO single crystal (GZOSC), which have the advantages of high conductivity, high carrier mobility and high thermal stability. When it was employed as a photoanode in the DSSCs, the cell exhibited a 1.44% power-conversion efficiency under the illumination of one sun (AM 1.5G). The performance is superior to our ZnO nanowires/FTO based DSSCs under the same condition. This enhanced performance is mainly attributed to the perfect interface between the ZnO nanowires and the GZOSC substrate that contributes to lower carrier scattering and recombination rates compared with that grown on traditional FTO substrate.

  17. Sodium and potassium doped P-type ZnO films by sol-gel spin-coating technique

    Science.gov (United States)

    Au, Benedict Wen-Cheun; Chan, Kah-Yoong

    2017-07-01

    Zinc oxide (ZnO) is a promising material in a variety of applications including sensors, transistors and solar cells. Many researchers studied N-type ZnO films and reported enhanced properties. On the other hand, P-type ZnO films were rarely attempted due to the self-compensation effect. Success in achieving P-type ZnO films is important as it will pave the way for more advanced complementary devices. In this work, P-type sodium and potassium doped ZnO films were fabricated on glass substrates with doping concentration between 0 and 25 at.%. The influences of doping concentration on surface morphology, structural, optical and electrical properties were investigated using atomic force microscopy, X-ray diffraction spectroscopy, energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometer, photoluminescence spectroscopy and Hall-effect electrical transport measurement system. The distinctive behavior of P-type ZnO films with different doping concentrations will be discussed.

  18. Boron-doped MnTe semiconductor-sensitized ZnO solar cells

    Indian Academy of Sciences (India)

    Auttasit Tubtimtae; Suwanna Sheangliw; Kritsada Hongsith; Supab Choopun

    2014-10-01

    We studied the photovoltaic performance of boron-doped MnTe semiconductor-sensitized solar cells (B-doped MnTe SSCs). The B-doped MnTe semiconductor was grown on ZnO using two stages of the successive ionic layer adsorption and reaction (SILAR) technique. The two phases of B-doped semiconductor nanoparticles (NPs), i.e. MnTe and MnTe2 were observed with a diameter range of approximately 15–30 nm. The result of the energy conversion efficiency of the sample with boron doping was superior compared to that of an undoped sample, due to the substantial change in the short-circuit current density and the open-circuit voltage. In addition, plots of ( ℎ )2 vs ℎ with band gaps of 1.30 and 1.27 eV were determined for the undoped and B-doped MnTe NPs, respectively. It can be noted that the boron doping effects with the change in the band gap and lead to an improvement in the crystalline quality and also intimate contact between the larger sizes of MnTe NPs. Hence, a noticeably improved photovoltaic performance resulted. However, this kind of semiconductor sensitizer can be further extended by experiments on yielding a higher power conversion efficiency and greater stability of the device.

  19. Engineering of electronic and optical properties of ZnO thin films via Cu doping

    Institute of Scientific and Technical Information of China (English)

    Zhang Guo-Heng; Deng Xiao-Yan; Xue Hua; Xiang Gang

    2013-01-01

    ZnO thin films doped with different Cu concentrations are fabricated by reactive magnetron sputtering technique.XRD analysis indicates that the crystal quality of the ZnO:Cu film can be enhanced by a moderate level of Cu-doping in the sputtering process.The results of XPS spectra of zinc,oxygen,and copper elements show that Cu-doping has an evident and complicated effect on the chemical state of oxygen,but little effect on those of zinc and copper.Interestingly,further investigation of the optical properties of ZnO:Cu samples shows that the transmittance spectra exhibit both red shift and blue shift with the increase of Cu doping,in contrast to the simple monotonic behavior of the Burstein-Moss effect.Analysis reveals that this is due to the competition between oxygen vacancies and intrinsic and surface states of oxygen in the sample.Our result may suggest an effective way of tuning the bandgap of ZnO samples.

  20. Exploration of Al-Doped ZnO in Photovoltaic Thin Films

    Science.gov (United States)

    Ciccarino, Christopher; Sahiner, M. Alper

    The electrical properties of Al doped ZnO-based thin films represent a potential advancement in the push for increasing solar cell efficiency. Doping with Aluminum will theoretically decrease resistivity of the film and therefore achieve this potential as a viable option in the P-N junction phase of photovoltaic cells. The n-type semi-conductive characteristics of the ZnO layer will theoretically be optimized with the addition of Aluminum carriers. In this study, Aluminum doping concentrations ranging from 1-3% by mass were produced, analyzed, and compared. Films were developed onto ITO coated glass using the Pulsed Laser Deposition technique. Target thickness was 250 nm and ellipsometry measurements showed uniformity and accuracy in this regard. Active dopant concentrations were determined using Hall Effect measurements. Efficiency measurements showed possible applications of this doped compound, with upwards of 7% efficiency measured, using a Keithley 2602 SourceMeter set-up. XRD scans showed highly crystalline structures, with effective Al intertwining of the hexagonal wurtzile ZnO molecular structure. This alone indicates a promising future of collaboration between these two materials.

  1. Determining the thermophysical properties of Al-doped ZnO nanoparticles by the photoacoustic technique

    Institute of Scientific and Technical Information of China (English)

    T.A.El-Brolossy; O.Saber; S.S.Ibrahim

    2013-01-01

    The thermal conductivity and specific heat capacity of undoped and Al-doped (1-10 at.%) ZnO nanoparticles prepared using the solvent thermal method are determined by measuring both thermal diffusivity and thermal effusivity of a pressed powder compact of the prepared nanoparticles by using the laser-induced photoacoustic technique.The impact of Al doping versus the microstructure of the samples on such thermal parameters has been investigated.The results reveal an obvious enhancement in the specific heat capacity when decreasing the particle size,while the effect of Al doping on the specific heat capacity is minor.The measured thermal conductivities are about one order of magnitude smaller than that of the bulk ZnO due to several nested reducing heat transfer mechanisms.The results also show that Al doping significantly influences the thermal resistance.Using a simple thermal impedance model,the added thermal resistance due to Al dopant has been estimated.

  2. Structural, electrical and optical studies on ruthenium doped ZnO pellets for device applications

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Arindam [Department of Physics, National Institute of Technology Silchar, Assam 788010 (India); Department of Physics, Don Bosco College, Tura, Meghalaya 794002 (India); Kumari, Navnita [Department of Physics, Indian Institute of Technology, Delhi 110016 (India); Tewari, Sujit [Department of Physics, Karimganj College, Karimganj, Assam 788710 (India); Bhattacharjee, Ayon, E-mail: ayonbh@gmail.com [Department of Physics, National Institute of Technology Silchar, Assam 788010 (India); Department of Physics, National Institute of Technology Meghalaya, Shillong 793003 (India)

    2015-06-15

    Highlights: • Synthesis of polycrystalline ZnO by chemical route. • Change in crystallite size with increasing doping concentration. • Dopant dependency of ac conductivity. • Inter-band transitions at the fundamental edge. • Bowing/narrowing of the bandgap with doping. - Abstract: Doped and undoped specimens of nano-particulate ZnO with 0.5 wt% and 1 wt% ruthenium were prepared through a chemical route. Structural characterization of the samples performed with XRD established that all the nanoparticles are of zinc oxide having polycrystalline nature. Morphological studies were conducted using FESEM to confirm the grain size and texture. Electrical measurements showed that the ac conductivity increases with frequency but decreases with increasing ruthenium concentration, making it a potential option for device applications. It is found that the absorbance does not significantly change with doping. The above fact is further confirmed from the bandgap calculations using the reflectance graphs. A decrease of bandgap from 3.42 to 3.19 eV with increasing Ru concentration is observed making it an important and advantageous material for potential visible light photocatalytic applications involving metal oxide nanostructures.

  3. Characterization of Fe$^{3+}$-doped silver phosphate glasses

    Indian Academy of Sciences (India)

    B P CHOUDHARY; N B SINGH

    2016-12-01

    The relationship among the composition, structure and selected properties for five series of silver phosphate glasses containing 0, 5, 10, 15 and 20wt% Fe$_2$O$_3$ has been investigated. The synthesized glasses have been characterized using different experimental techniques. X-ray diffraction studies revealed that the glasses are amorphous in nature. IR spectral studies have shown the presence of characteristic P–O–P linkages of linear phosphate chains,presence of O–P–O units in the phosphate tetrahedral and the formation of P–O–Fe bonds in the doped glass. It is also confirmed that due to doping of Fe$_2$O$_3$, loosening of glassy structure occurred and the glass became more disordered. Differential scanning calorimetric (DSC) studies revealed that glass transition temperature increased with Fe$_2$O$_3$ concentration. Scanning electron microscopic studies have shown that Fe$_2$O$_3$ doping modifies the microstructures of the glass and at lower concentration of dopant, a nanostructure is obtained. Electrical conductivity measurements from 303 to 373 K in a frequency range from 100 Hz to 5 MHz have indicated that all glasses are ionic conductors with Ag$^+$ ions as the charge carrier. Fe$_2$O$_3$ doping in silver phosphate glass increased the electrical conductivities. Results have shown that dielectric constants increased with the increase of temperature at all the frequencies; a.c. and d.c. conductivities have been separated and a Cole–Cole plot is also drawn. Dielectric losses in all the glasses decreased with frequency at a particular temperature. It is found that Ag$_2$O–P$_2$O$_5$ glass doped with 5wt% Fe$_2$O$_3$ gives high OCV value and the doped glass can be used as an electrolyte for solid-state batteries.

  4. Enhanced gas sensing performance of Li-doped ZnO nanoparticle film by the synergistic effect of oxygen interstitials and oxygen vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jianwei; Xie, Changsheng, E-mail: csxie@mail.hust.edu.cn; Yang, Li; Zhang, Shunping; Zhang, Guozhu; Cai, Ziming

    2015-03-01

    Highlights: • Lithium can enhance the sensing performance of ZnO. • The effects of Li doping were investigated using temperature dependent conductivity measurements. • Li doped ZnO can induce two forms of oxygen defects: oxygen vacancies and oxygen interstitials. • The synergistic effect of oxygen vacancies and oxygen interstitials is responsible for the sensing performance enhancement of Li doped ZnO. - Abstract: Li doped ZnO (Zn{sub 1−x}Li{sub x}O) nanoparticles with different content were synthesized. X-ray photoelectron spectroscopy (XPS) indicated that the ratio of oxygen to zinc for ZnO increased with increasing of Li content from x = 0 to 0.2, which had been attributed to the introduction of oxygen interstitial by Li dopant. The sensing performance and the temperature-dependent conductivity were investigated. It is observed that Li doped ZnO showed higher sensitivity and selectivity compared to the undoped ZnO. The 0.1 Li doped ZnO performed the maximum responses of 71.5 and 40.2 for 100 ppm methanol and formaldehyde, respectively, at 350 °C. The research showed that the oxygen vacancies served as active sites which supported the oxygen adsorption and reaction, oxygen interstitials served as active sites to oxidize the reducing gases and produce electrons. The enhanced sensing performance of Li doped ZnO was attributed to the synergistic effect of oxygen interstitials and oxygen vacancies.

  5. Magnetic and photocatalytic response of Ag-doped ZnFeO nano-composites for photocatalytic degradation of reactive dyes in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Mahmood, Asif, E-mail: ahayat@ksu.edu.sa [College of Engineering, Department of Chemical Engineering, King Saud University, Riyadh (Saudi Arabia); Ramay, Shahid Mahmood [College of Science, Department of Physics and Astronomy, King Saud University, Riyadh (Saudi Arabia); Al-Zaghayer, Yousef S. [College of Engineering, Department of Chemical Engineering, King Saud University, Riyadh (Saudi Arabia); Industrial Catalysts Research Chair, King Saud University, Riyadh 11421 (Saudi Arabia); Imran, Muhammad [College of Engineering, Department of Chemical Engineering, King Saud University, Riyadh (Saudi Arabia); Atiq, Shahid [Centre of Excellence in Solid State Physics, University of the Punjab, New Campus, Lahore 54590 (Pakistan); Al-Johani, Meshal S. [Energy Research Institute, King Abdulaziz City for Science and Technology (KACST), Riyadh 11442 (Saudi Arabia)

    2014-11-25

    Highlights: • Self-consistent sol–gel based auto-combustion route was used. • Photocatalytic degradation of reactive dyes in aqueous solution was investigated. • Due to Ag doping, band gap reduced. • Activity of Ag-doped samples was higher than that of un-doped ones. - Abstract: To investigate the photocatalytic degradation of reactive dyes in aqueous solution, pure ZnO and Fe/Ag-doped magnetic photocatalysts having nominal compositions of Zn{sub 0.95−x}Fe{sub 0.05}Ag{sub x}O (x = 0.0, 0.05 and 0.1) have been synthesized via self-consistent sol–gel based auto-combustion route. Thermally stable samples were subsequently confirmed to exhibit wurtzite type hexagonal structure, characteristic of ZnO. The nature of chemical bonding was elaborated by Fourier transform analysis. Electron microscopic techniques were employed to investigate the structural morphology and to evaluate the particle size. Ferromagnetic nature of the Fe/Ag doped samples was revealed by vibrating sample magnetometry, enabling the photocatalytic samples to be re-collected magnetically for repeated usage. The enhanced photocatalytic activity in the degradation of methylene blue under UV light irradiation with 5 and 10 wt.% Ag/ZnFeO has been observed validating the potential applications of these materials in the field of photo-degradation of organic pollutants.

  6. Effect of substrate temperature on transparent conducting Al and F co-doped ZnO thin films prepared by rf magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Fang-Hsing, E-mail: fansen@dragon.nchu.edu.tw; Chang, Chiao-Lu

    2016-05-01

    Highlights: • Al and F co-doped ZnO (AFZO) thin films were prepared by rf magnetron sputtering. • Effects of substrate temperature on properties of AFZO films were investigated. • The AFZO films show a typical hexagonal wurtzite structure and are (0 0 2) oriented. • The AFZO thin film prepared at 200 °C exhibits a low resistivity of 2.88 × 10{sup −4} Ω-cm. • The average visible transmittances of all the AFZO thin films exceed 92%. - Abstract: ZnO is a wide bandgap semiconductor that has many potential applications such as solar cells, thin film transistors, light emitting diodes, and gas/biological sensors. In this study, a composite ceramic ZnO target containing 1 wt% Al{sub 2}O{sub 3} and 1.5 wt% ZnF{sub 2} was prepared and used to deposit transparent conducting Al and F co-doped zinc oxide (AFZO) thin films on glass substrates by radio frequency magnetron sputtering. The effect of substrate temperatures ranging from room temperature (RT) to 200 °C on structural, morphological, electrical, chemical, and optical properties of the deposited thin films were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), Hall effect measurement, X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and UV–vis spectrophotometer. The XRD results showed that all the AFZO thin films had a (0 0 2) diffraction peak, indicating a typical wurtzite structure with a preferential orientation of the c-axis perpendicular to the substrate. The FE-SEM and AFM analyses indicated that the crystallinity and grain size of the films were enhanced while the surface roughness decreased as the substrate temperature increased. Results of Hall effect measurement showed that Al and F co-doping decreased the resistivity more effectively than single-doping (either Al or F doping) in ZnO thin films. The resistivity of the AFZO thin films decreased from 5.48 × 10{sup −4} to 2.88 × 10{sup −4}

  7. Influence of Ce doping on microstructure of ZnO nanoparticles and their acetone sensing properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, F.M.; Li, X.B. [College of Physics and Electronic Engineering, Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, Northwest Normal University, Lanzhou, Gansu 730070 (China); National Laboratory of Solid State Microstructures & Eco-Materials and Renewable Energy Research Center (ERERC) at Department of Physics, Nanjing University, Nanjing 210093 (China); Ma, S.Y., E-mail: lifaming1108074@sina.com [College of Physics and Electronic Engineering, Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, Northwest Normal University, Lanzhou, Gansu 730070 (China); Chen, L.; Li, W.Q.; Zhu, C.T.; Xu, X.L. [College of Physics and Electronic Engineering, Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, Northwest Normal University, Lanzhou, Gansu 730070 (China); Chen, Y. [Northwest University for Nationality, Lanzhou, Gansu 730030 (China); Li, Y.F.; Lawson, G. [Atech Systems, 6110 W. Highway 290, Austin, TX 78735 (United States)

    2015-11-15

    Electrospinning technology was generally used to synthesis nanofiber, here we use it to fabricate pure ZnO nanoparticles (ZnO NPs) and Ce-doped (0.1 wt%, 0.8 wt%, 1.5 wt%) ZnO nanoparticles (ZnO:Ce NPs) via decrease the molecular weight of PVP in precursor liquid. Their microstructures were characterized by X-ray diffraction, scanning electron microscopy, Brunauer-Emmet-Teller and photoluminescence spectra. The results clearly indicated that the 0.8 wt% ZnO:Ce NPs shows smaller average grain size (70 nm) and a higher specific surface area (21.5 m{sup 2}/g). The testing on gas sensing performance revealed that the 0.8 wt% ZnO:Ce NPs based sensor shows the highest response values and a well selectivity to acetone. The response and recovery time of ZnO NPs based sensors to 100 ppm acetone was about 13 and 7 s while these are about 10 and 9 s in ZnO:Ce NPs based sensors, respectively. These results demonstrated that the 0.8 wt% ZnO:Ce NPs based sensor can rapidly be detect and distinguish accurately acetone in ambient air. Moreover, the sensor shows good long-term stability and reproducibility of response. The sensing mechanism was also discussed and the results indicated that the gas diffusing channels and the electron depleted layer of the ZnO NPs based sensor was increased markedly after Ce-doped, which results in the response of the ZnO:Ce NPs based sensor increased. - Highlights: • The loose mesostructured provide more channel for gas diffusion. • Smaller average grain size (70 nm) and higher specific surface area (21.5 m{sup 2}/g). • The response and recovery time of ZnO:Ce NPs based sensor was about 10 and 9 s. • Suitable Ce-doped could improve the response of the ZnO NPs base sensors.

  8. Magnetic study of Fe{sub 2}O{sub 3}/ZnO nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Guskos, N. [Solid State Section, Department of Physics, University of Athens, Panepistimiopolis 15-784 (Greece); Institute of Physics, Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin (Poland); Glenis, S. [Solid State Section, Department of Physics, University of Athens, Panepistimiopolis 15-784 (Greece); Zolnierkiewicz, G. [Institute of Physics, Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin (Poland); Typek, J., E-mail: typjan@zut.edu.p [Institute of Physics, Pomeranian University of Technology, Al. Piastow 48, 70-311 Szczecin (Poland); Sibera, D.; Kaszewski, J.; Moszynski, D. [Institute of Chemical and Environmental Engineering, Pomeranian University of Technology, Al. Piastow 17, 70-310 Szczecin (Poland); Lojkowski, W. [Institute of High Pressure Physics of the Polish Academy of the Sciences, SokoLowska 29/37, 01-142 Warszawa (Poland); Narkiewicz, U. [Institute of Chemical and Environmental Engineering, Pomeranian University of Technology, Al. Piastow 17, 70-310 Szczecin (Poland)

    2010-09-15

    Fine particles of Fe{sub 2}O{sub 3}/ZnO were synthesized by wet chemical method. The morphological and structural properties of the mixed system were investigated by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. The major phase was determined to be the cubic spinel phase of {gamma}-Fe{sub 2}O{sub 3} maghemite with mean crystalline size of about 20 nm together with small amounts of hexagonal ZnO and ZnFe{sub 2}O{sub 4}. The magnetic properties of the material were investigated by ferromagnetic resonance (FMR) in the temperature range from liquid helium to room temperature. An asymmetric and very intense FMR signal was recorded exhibiting strong shift to low magnetic fields with decrease in temperature. Analysis of the FMR spectra in terms of two separate line components indicates the presence of strongly anisotropic interactions.

  9. Structural and Optical Properties of Group III Doped Hydrothermal ZnO Thin Films

    Science.gov (United States)

    Mughal, Asad J.; Carberry, Benjamin; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.

    2017-03-01

    In this work, we employ a simple two-step growth technique to deposit impurity doped heteroepitaxial thin films of (0001) ZnO onto (111) MgAl2O4 spinel substrates through a combination of atomic layer deposition (ALD) and hydrothermal growth. The hydrothermal layer is doped with Al, Ga, and In through the addition of their respective nitrate salts. We evaluated the effect that varying the concentrations of these dopants has on both the structural and optical properties of these films. It was found that the epitaxial ALD layer created a ZnO}} } . out-of-plane orientation and a ZnO}} } . in-plane orientation between the film and substrate. The rocking curve line widths ranged between 0.75° and 1.80° depending on dopant concentration. The optical bandgap determined through the Tauc method was between 3.28 eV and 3.39 eV and showed a Burstein-Moss shift with increasing dopant concentration.

  10. High-quality ZnO growth, doping, and polarization effect

    Science.gov (United States)

    Kun, Tang; Shulin, Gu; Jiandong, Ye; Shunming, Zhu; Rong, Zhang; Youdou, Zheng

    2016-03-01

    The authors have reported their recent progress in the research field of ZnO materials as well as the corresponding global advance. Recent results regarding (1) the development of high-quality epitaxy techniques, (2) the defect physics and the Te/N co-doping mechanism for p-type conduction, and (3) the design, realization, and properties of the ZnMgO/ZnO hetero-structures have been shown and discussed. A complete technology of the growth of high-quality ZnO epi-films and nano-crystals has been developed. The co-doping of N plus an iso-valent element to oxygen has been found to be the most hopeful path to overcome the notorious p-type hurdle. High mobility electrons have been observed in low-dimensional structures utilizing the polarization of ZnMgO and ZnO. Very different properties as well as new physics of the electrons in 2DEG and 3DES have been found as compared to the electrons in the bulk. Project supported by the National Natural Science Foundation of China (Nos. 61025020, 61274058, 61322403, 61504057, 61574075), the Natural Science Foundation of Jiangsu Province (Nos. BK2011437, BK20130013, BK20150585), the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Fundamental Research Funds for the Central Universities.

  11. Structural and Optical Properties of Group III Doped Hydrothermal ZnO Thin Films

    Science.gov (United States)

    Mughal, Asad J.; Carberry, Benjamin; Speck, James S.; Nakamura, Shuji; DenBaars, Steven P.

    2017-01-01

    In this work, we employ a simple two-step growth technique to deposit impurity doped heteroepitaxial thin films of (0001) ZnO onto (111) MgAl2O4 spinel substrates through a combination of atomic layer deposition (ALD) and hydrothermal growth. The hydrothermal layer is doped with Al, Ga, and In through the addition of their respective nitrate salts. We evaluated the effect that varying the concentrations of these dopants has on both the structural and optical properties of these films. It was found that the epitaxial ALD layer created a ZnO}} } out-of-plane orientation and a ZnO}} } in-plane orientation between the film and substrate. The rocking curve line widths ranged between 0.75° and 1.80° depending on dopant concentration. The optical bandgap determined through the Tauc method was between 3.28 eV and 3.39 eV and showed a Burstein-Moss shift with increasing dopant concentration.

  12. Pulsed laser deposited Al-doped ZnO thin films for optical applications

    Directory of Open Access Journals (Sweden)

    Gurpreet Kaur

    2015-02-01

    Full Text Available Highly transparent and conducting Al-doped ZnO (Al:ZnO thin films were grown on glass substrates using pulsed laser deposition technique. The profound effect of film thickness on the structural, optical and electrical properties of Al:ZnO thin films was observed. The X-ray diffraction depicts c-axis, plane (002 oriented thin films with hexagonal wurtzite crystal structure. Al-doping in ZnO introduces a compressive stress in the films which increase with the film thickness. AFM images reveal the columnar grain formation with low surface roughness. The versatile optical properties of Al:ZnO thin films are important for applications such as transparent electromagnetic interference (EMI shielding materials and solar cells. The obtained optical band gap (3.2–3.08 eV was found to be less than pure ZnO (3.37 eV films. The lowering in the band gap in Al:ZnO thin films could be attributed to band edge bending phenomena. The photoluminescence spectra gives sharp visible emission peaks, enables Al:ZnO thin films for light emitting devices (LEDs applications. The current–voltage (I–V measurements show the ohmic behavior of the films with resistivity (ρ~10−3 Ω cm.

  13. Preparation of cadmium-doped ZnO thin films by SILAR and their characterization

    Indian Academy of Sciences (India)

    S Mondal; P Mitra

    2012-10-01

    Cadmium-doped zinc oxide (Cd : ZnO) thin films were deposited from sodium zincate bath following a chemical dipping technique called successive ion layer adsorption and reaction (SILAR). Structural characterization by X-ray diffraction reveals that polycrystalline nature of the films increases with increasing cadmium incorporation. Particle size evaluated using X-ray line broadening analysis shows decreasing trend with increasing cadmium impurification. The average particle size for pure ZnO is 36.73nm and it reduces to 29.9 nm for 10% Cd:ZnO, neglecting strain broadening. The strong preferred c-axis orientation is lost due to cadmium doping and degree of polycrystallinity of the films also increases with increasing Cd incorporation. Incorporation of cadmium was confirmed from elemental analysis using EDX. The optical bandgap of the films decreases with increasing Cd dopant. The value of fundamental absorption edge is 3.18 eV for pure ZnO and it decreases to 3.11 eV for 10% Cd:ZnO.

  14. Significant mobility enhancement in extremely thin highly doped ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Look, David C., E-mail: david.look@wright.edu [Semiconductor Research Center, Wright State University, 3640 Colonel Glenn Hwy., Dayton, Ohio 45435 (United States); Wyle Laboratories, Inc., 2601 Mission Point Blvd., Dayton, Ohio 45431 (United States); Air Force Research Laboratory Sensors Directorate, 2241 Avionics Circle, Wright-Patterson AFB, Ohio 45433 (United States); Heller, Eric R. [Air Force Research Laboratory Materials and Manufacturing Directorate, 3005 Hobson Way, Wright-Patterson AFB, Ohio 45433 (United States); Yao, Yu-Feng; Yang, C. C., E-mail: ccycc@ntu.edu.tw [Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan (China)

    2015-04-13

    Highly Ga-doped ZnO (GZO) films of thicknesses d = 5, 25, 50, and 300 nm, grown on 160-nm ZnO buffer layers by molecular beam epitaxy, had 294-K Hall-effect mobilities μ{sub H} of 64.1, 43.4, 37.0, and 34.2 cm{sup 2}/V-s, respectively. This extremely unusual ordering of μ{sub H} vs d is explained by the existence of a very high-mobility Debye tail in the ZnO, arising from the large Fermi-level mismatch between the GZO and the ZnO. Scattering theory in conjunction with Poisson analysis predicts a Debye-tail mobility of 206 cm{sup 2}/V-s at the interface (z = d), falling to 58 cm{sup 2}/V-s at z = d + 2 nm. Excellent fits to μ{sub H} vs d and sheet concentration n{sub s} vs d are obtained with no adjustable parameters.

  15. Effects of free electrons and quantum confinement in ultrathin ZnO films: a comparison between undoped and Al-doped ZnO.

    Science.gov (United States)

    Li, X D; Chen, T P; Liu, P; Liu, Y; Leong, K C

    2013-06-17

    Band gaps and exciton binding energies of undoped and Al-doped ZnO thin films were determined from optical absorption measurement based on the Elliott's exciton absorption theory. As compared to the undoped films, the doped films exhibit a band gap expansion and a reduction in the exciton binding energies due to the free electron screening effect, which suppresses the excitonic absorption and results in a blue shift of the absorption edge. The undoped and doped films show the same quantum size dependence, i.e. both the exciton binding energies and band gap energies increase with decreasing grain size of the oxides.

  16. Epitaxial Properties of Co-Doped ZnO Thin Films Grown by Plasma Assisted Molecular Beam Epitaxy

    Institute of Scientific and Technical Information of China (English)

    CAO Qiang; DENG Jiang-Xia; LIU Guo-Lei; CHEN Yan-Xue; YAN Shi-Shen

    2007-01-01

    High quality Co-doped ZnO thin films are grown on single crystalline Al2O3(0001) and ZnO(0001) substrates by oxygen plasma assisted molecular beam epitaxy at a relatively lower substrate temperature of 450 ℃. The epitaxial conditions are examined with in-situ reflection high energy electron diffraction (RHEED) and ex-situ high resolution x-ray diffraction (HRXRD). The epitaxial thin films are single crystal at film thickness smaller than 500nm and nominal concentration of Co dopant up to 20%. It is indicated that the Co cation is incorporated into the ZnO matrix as Co2+ substituting Zn2+ ions. Atomic force microscopy shows smooth surfaces with rms roughness of 1.9nm. Room-temperature magnetization measurements reveal that the Co-doped ZnO thin films are ferromagnetic with Curie temperatures TC above room temperature.

  17. A CEMS search for precipitate formation in 57Fe implanted ZnO

    Science.gov (United States)

    Bharuth-Ram, Krishanlal; Masenda, Hilary; Doyle, Terence B.; Geburt, Sebastian; Ronning, Carsten; Gunnlaugsson, Harald Palle

    2012-03-01

    Conversion electron Mössbauer Spectroscopy measurements have been made on ZnO single crystals implanted with 60 keV 57Fe to 4 and 8 at.% peak concentrations, and annealed up to 800°C. The spectra show quite strong changes with annealing, but no evidence of magnetic components, thus precluding the formation of large sized precipitates or secondary phases. Above an annealing temperature of 650°C, the dominant spectral component is a doublet with hyperfine parameters typical of Fe3 + , which is attributed to Fe3 + ions in nano-precipitates ˜5 nm in size.

  18. Effect of deposition parameters and strontium doping on characteristics of nanostructured ZnO thin film by chemical bath deposition method

    Energy Technology Data Exchange (ETDEWEB)

    Sheeba, N. H., E-mail: sheebames.naser@gmail.com [M.E.S. Asmabi College, P. Vemballur, Thrissur, Kerala (India); Naduvath, J., E-mail: johnsnaduvath@gmail.com [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology, Mumbai (India); Abraham, A., E-mail: anithakklm@gmail.com; Philip, R. R., E-mail: reenatara@rediffmail.com [Thin Film Research Lab, U.C. College, Aluva, Kerala (India); Weiss, M. P., E-mail: matthew@hope.edu, E-mail: zachary.diener@hope.edu, E-mail: remillard@hope.edu, E-mail: deyoung@hope.edu; Diener, Z. J., E-mail: matthew@hope.edu, E-mail: zachary.diener@hope.edu, E-mail: remillard@hope.edu, E-mail: deyoung@hope.edu; Remillard, S. K., E-mail: matthew@hope.edu, E-mail: zachary.diener@hope.edu, E-mail: remillard@hope.edu, E-mail: deyoung@hope.edu; DeYoung, P. A., E-mail: matthew@hope.edu, E-mail: zachary.diener@hope.edu, E-mail: remillard@hope.edu, E-mail: deyoung@hope.edu [Hope Ion Beam Accelerator Laboratory, Hope College, Holland, MI (United States)

    2014-10-15

    Polycrystalline thin films of ZnO and Sr-doped ZnO (ZnO:Sr) on ultrasonically cleaned soda lime glass substrates are synthesized through successive ionic layer adsorption and reaction. The XRD profiles of ZnO and ZnO:Sr films prepared at different number of deposition cycles exhibit hexagonal wurtzite structure with preferred orientation along (002) direction. The crystallites are found to be nano sized, having variation in size with the increase in number of depositions cycles and also with Sr doping. Optical absorbance studies reveal a systematically controllable blueshift in band gap of Sr-doped ZnO films. SEM images indicate enhanced assembling of crystallites to form elongated rods as number of dips increased in Sr doped ZnO. The films are found to be n-type with the Sr doping having little effect on the electrical properties.

  19. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning.

    Science.gov (United States)

    Zhang, H D; Yu, M; Zhang, J C; Sheng, C H; Yan, X; Han, W P; Liu, Y C; Chen, S; Shen, G Z; Long, Y Z

    2015-06-21

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  20. Effect of deposition parameters and strontium doping on characteristics of nanostructured ZnO thin film by chemical bath deposition method

    Science.gov (United States)

    Sheeba, N. H.; Naduvath, J.; Abraham, A.; Weiss, M. P.; Diener, Z. J.; Remillard, S. K.; DeYoung, P. A.; Philip, R. R.

    2014-10-01

    Polycrystalline thin films of ZnO and Sr-doped ZnO (ZnO:Sr) on ultrasonically cleaned soda lime glass substrates are synthesized through successive ionic layer adsorption and reaction. The XRD profiles of ZnO and ZnO:Sr films prepared at different number of deposition cycles exhibit hexagonal wurtzite structure with preferred orientation along (002) direction. The crystallites are found to be nano sized, having variation in size with the increase in number of depositions cycles and also with Sr doping. Optical absorbance studies reveal a systematically controllable blueshift in band gap of Sr-doped ZnO films. SEM images indicate enhanced assembling of crystallites to form elongated rods as number of dips increased in Sr doped ZnO. The films are found to be n-type with the Sr doping having little effect on the electrical properties.

  1. Fabrication and photoelectric properties of La-doped p-type ZnO nanofibers and crossed p-n homojunctions by electrospinning

    Science.gov (United States)

    Zhang, H. D.; Yu, M.; Zhang, J. C.; Sheng, C. H.; Yan, X.; Han, W. P.; Liu, Y. C.; Chen, S.; Shen, G. Z.; Long, Y. Z.

    2015-06-01

    La-doped p-type ZnO nanofibers were successfully synthesized by electrospinning, followed by calcination. The microstructure and morphology of the La-doped ZnO nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The field effect curve of individual nanofibers confirms that the resulting La-doped ZnO fibers are p-type semiconductors. The doping mechanism is discussed. Furthermore, crossed p-n homojunction nanofibers were also prepared based on electrospun La-doped p-type ZnO and n-type pure ZnO fibers. The current-voltage curve shows the typical rectifying characteristic of a p-n homojunction device. The turn-on voltage appears at about 2.5 V under the forward bias and the reverse current is impassable.

  2. Structural, chemical and optical evaluation of Cu-doped ZnO nanoparticles synthesized by an aqueous solution method

    Energy Technology Data Exchange (ETDEWEB)

    Iribarren, A., E-mail: augusto@imre.oc.uh.cu [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba); Hernández-Rodríguez, E. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba); Maqueira, L. [Instituto de Ciencia y Tecnología de Materiales (IMRE), Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba); Facultad de Química, Universidad de La Habana, Zapata y G, Vedado, Plaza, La Habana 10400 (Cuba)

    2014-12-15

    Highlights: • Cu-doped ZnO nanoparticles obtained by chemical synthesis. • Substitutional or interstitial Cu into ZnO lead specific structural, chemical, and optical changes. • Incorporation efficiency of Cu atoms in ZnO as a function of the Cu concentration in the precursor dissolution. - Abstract: In this work a study of ZnO and Cu-doped ZnO nanoparticles obtained by chemical synthesis in aqueous media was carried out. Structural analysis gave the dominant presence of wurtzite ZnO phase forming a solid solution Zn{sub 1−x}Cu{sub x}O. For high Cu doping CuO phase is also present. For low Cu concentration the lattice shrinks due to Cu atoms substitute Zn atoms. For high Cu concentration the lattice enlarges due to predominance of interstitial Cu. From elemental analysis we determined and analyzed the incorporation efficiency of Cu atoms in Zn{sub 1−x}Cu{sub x}O as a function of the Cu concentration in the precursor dissolution. Combining structural and chemical results we described the Cu/Zn precursor concentrations r{sub w} in which the solid solution of Cu in ZnO is predominant. In the region located at r{sub w} ≈ 0.2–0.3 it is no longer valid. For Cu/Zn precursor concentration r{sub w} > 0.3 interstitial Cu dominates, and some amount of copper oxide appears. As the Cu concentration increases, the effective size of nanoparticles decreases. Photoluminescence (PL) measurements of the Cu-doped ZnO nanoparticles were carried out and analyzed.

  3. Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells.

    Science.gov (United States)

    Akhtar, Mohd Javed; Alhadlaq, Hisham A; Alshamsan, Aws; Majeed Khan, M A; Ahamed, Maqusood

    2015-09-08

    We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

  4. Controllable hydrothermal synthesis of ZnO nanowires arrays on Al-doped ZnO seed layer and patterning of ZnO nanowires arrays via surface modification of substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Jin [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Que Wenxiu, E-mail: wxque@mail.xjtu.edu.cn [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Jia Qiaoying [Electronic Materials Research Laboratory, School of Electronic and Information Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China); Ye Xiangdong; Ding Yucheng [State Key Laboratory of Manufacturing Systems Engineering, Xi' an Jiaotong University, Xi' an 710049, Shaanxi (China)

    2011-09-15

    ZnO nanowire (NW) arrays are assembled on the Al-doped ZnO (AZO) seed layer by a hydrothermal process. Effects of the temperature and growth time of the hydrothermal process on morphological and photoluminescence properties of the as-assembled ZnO NW arrays are characterized and studied. Results indicate that the length and diameter of the ZnO NWs increase with a lengthening of the growth time at 80 deg. C and the hydrothermal temperature has a significant effect on the growth rate and the photoluminescence properties of the ZnO NW arrays. The patterned AZO seed layer is fabricated on a silicon substrate by combining a sol-gel process with an electron-beam lithography process, as well as a surface fluorination technique, and then the ZnO NW arrays are selectively grown on those patterned regions of the AZO seed layer by the hydrothermal process. Room-temperature photoluminescence spectra of the patterned ZnO NW arrays shows that only a strong UV emission at about 380 nm is observed, which implies that few crystal defects exist inside the as-grown ZnO NW arrays.

  5. Effect of Annealing Temperature on Structural and Optical Properties of N-Doped ZnO Films

    Institute of Scientific and Technical Information of China (English)

    ZHONG Sheng; ZHANG Wei-Ying; WU Xiao-Peng; LIN Bi-Xia; FU Zhu-Xi

    2008-01-01

    Nitrogen-doped ZnO (ZnO: N) films are prepared by thermal oxidation of sputtered Zn,3N,2 layers on Al,2O,3 substrates. The correlation between the structural and optical properties of ZnO: N films and annealing temperatures is investigated. X-ray diffraction result demonstrates that the as-sputtered Zn,3N,2 films are transformed into ZnO: N films after annealing above 600℃. X-ray photoelectron spectroscopy reveals that nitrogen has two chemical states in the ZnO: N films: the No acceptor and the double donor(N2)o. Due to the No acceptor, the hole concentration in the film annealed at 700℃ is predicted to be highest, which is also confirmed by Hall effect measurement. In addition, the temperature dependent photoluminescence spectra allow to calculate the nitrogen acceptor binding energy.

  6. Structural and room temperature ferromagnetic properties of Ni doped ZnO nanoparticles via low-temperature hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kun; Liu, Changzhen, E-mail: liuchangzhen94@163.com; Chen, Rui; Fang, Xiaoxiang; Wu, Xiuling; Liu, Jie

    2016-12-01

    A series of Zn{sub 1−x}Ni{sub x}O (x=0, 1%, 3%, 5%) nanoparticles have been synthesized via a low-temperature hydrothermal method. Influence of Ni doping concentration on the structure, morphology, optical properties and magnetism of the samples was investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis spectrophotometer and vibrating sample magnetometer instruments. The results show that the undoped and doped ZnO nanoparticles are both hexagonal wurtzite structures. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The images of SEM reveal that the structure of pure ZnO and Ni doped samples are nanoparticles which intended to form flakes with thickness of few nanometers, being overlain with each one to develop the network with some pores and voids. Based on the ultraviolet–visible (UV–vis) spectroscopy analysis, it indicates that the band gap energy decreases with the increasing concentration of Ni. Furthermore, The Ni doped ZnO samples didn't exhibit higher ultraviolet-light-driven photocatalytic activity compared to the undoped ZnO sample. Vibrating sample magnetometer was used for the magnetic property investigations, and the result indicates that room temperature ferromagnetism property of 3% Ni doped sample is attributed to oxygen vacancy and interaction between doped ions.

  7. Structural and room temperature ferromagnetic properties of Ni doped ZnO nanoparticles via low-temperature hydrothermal method

    Science.gov (United States)

    Xu, Kun; Liu, Changzhen; Chen, Rui; Fang, Xiaoxiang; Wu, Xiuling; Liu, Jie

    2016-12-01

    A series of Zn1-xNixO (x=0, 1%, 3%, 5%) nanoparticles have been synthesized via a low-temperature hydrothermal method. Influence of Ni doping concentration on the structure, morphology, optical properties and magnetism of the samples was investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV-vis spectrophotometer and vibrating sample magnetometer instruments. The results show that the undoped and doped ZnO nanoparticles are both hexagonal wurtzite structures. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The images of SEM reveal that the structure of pure ZnO and Ni doped samples are nanoparticles which intended to form flakes with thickness of few nanometers, being overlain with each one to develop the network with some pores and voids. Based on the ultraviolet-visible (UV-vis) spectroscopy analysis, it indicates that the band gap energy decreases with the increasing concentration of Ni. Furthermore, The Ni doped ZnO samples didn't exhibit higher ultraviolet-light-driven photocatalytic activity compared to the undoped ZnO sample. Vibrating sample magnetometer was used for the magnetic property investigations, and the result indicates that room temperature ferromagnetism property of 3% Ni doped sample is attributed to oxygen vacancy and interaction between doped ions.

  8. Microstructure and characterization of Al-doped ZnO films prepared by RF power sputtering on Al and ZnO targets

    Energy Technology Data Exchange (ETDEWEB)

    Tseng, Chun-An [Department of Mechanical Engineering, National Central University, Taiwan (China); Lin, Jing-Chie, E-mail: jclincom@cc.ncu.edu.tw [Department of Mechanical Engineering, National Central University, Taiwan (China); Institute of Material Science and Engineering, National Central University, Taiwan (China); Chang, Yu-Fong [Depar