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Sample records for 111in implanted zno

  1. Photoluminescence of He-implanted ZnO

    SciTech Connect

    Hamby, D. W.; Lucca, D. A.; Lee, J.-K.; Nastasi, Michael Anthony,

    2004-01-01

    A study of the effects of ion-implanted He{sup +} on the 4.2 K photoluminescence (PL) of ZnO is presented. This investigation is motivated by the need to further understand the effects of damage resulting from the implantation process on the PL of ZnO. For this study, 10 keV He{sup +} ions were implanted at a dose of 2.5 x 10{sup 13}/cm{sup 2} in the (0001) Zn-terminated surface. The implantation process is seen to reduce the overall luminescence efficiency, although the number and relative intensities of the bound-exciton peaks are observed to be similar to that of unimplanted ZnO. The 4.2 K PL of the implanted surface exhibits a broad orange/red peak near 1.86 eV nm and is attributed to damage introduced during the implantation process. This peak is identified as donor-acceptor pair (DAP) luminescence with a thermal activation energy of 11 meV. The 1.86 eV peak is not observed for H-implanted ZnO suggesting that H passivates the implantation-induced defects responsible for this luminescence.

  2. Continuous and Localized Mn Implantation of ZnO

    PubMed Central

    2009-01-01

    We present results derived from continuous and localized 35 keV55Mn+ion implantations into ZnO. Localized implantations were carried out by using self-ordered alumina membranes as masks leading to ordered arrays of implanted volumes on the substrate surfaces. Defects and vacancies in the small implantation volumes of ZnO were generated due to the implantation processes besides the creation of new phases. Rapid thermal annealing was applied in the case of continuous implantation. The samples were characterized by HRSEM, GIXRD, Raman spectroscopy and RBS/C. Magnetic characterization of the samples pointed out appreciable differences among the samples obtained by the different implantation methods. This fact was mainly attributed to the different volume/surface ratios present in the implanted zones as well as to the increase of Mn atom concentrations along the grain frontiers in the nanostructured surfaces. The samples also showed a ferromagnetic transition phase at temperature value higher than room temperature. PMID:20596285

  3. Nanocluster formation in Co/Fe implanted ZnO

    NASA Astrophysics Data System (ADS)

    Bharuth-Ram, K.; Masenda, H.; Doyle, T. B.; Geburt, S.; Ronning, C.

    2015-04-01

    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 59Co ions with respective fluences of 1.15×1016 ions/cm 2 and 4.17×1016 ions/cm 2, followed by implantation of 60 keV 57Fe to a fluence of 0.50×1016/cm 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 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 B/CoFe ion, in good agreement with observations for 5-8 nm sized Co nanoclusters in ZnO.

  4. Thermal stability of ion-implanted ZnO

    SciTech Connect

    Coleman, V; Tan, H; Jagadish, C; Kucheyev, S; Zou, J

    2005-06-16

    Zinc oxide single crystals implanted at room temperature with high-dose (1.4 x 10{sup 17} cm{sup -2}) 300 keV As{sup +} ions are annealed at 1000-1200 C. Damage recovery is studied by a combination of Rutherford backscattering/ channeling spectrometry (RBS/C), cross-sectional transmission electron microscopy (XTEM), and atomic force microscopy (AFM). Results show that such a thermal treatment leads to the decomposition and evaporation of the heavily-damaged layer instead of apparent defect recovery and recrystallization that could be inferred from RBS/C and XTEM data alone. Such a relatively poor thermal stability of heavily-damaged ZnO has significant implications for understanding results on thermal annealing of ion-implanted ZnO.

  5. Crystallographically oriented Zn nanocrystals formed in ZnO by Mn{sup +}-implantation

    SciTech Connect

    Li, Y. J.; Zhang, B.; Lu, W.; Wang, Y.; Zou, J.

    2008-09-29

    The nanostructural characteristics of ZnO implanted with Mn{sup +} to doses ranging from 1x10{sup 15} to 1x10{sup 17} cm{sup -2} are systematically studied for both as-implanted and postannealed cases. The detailed structural characterizations confirmed that the Mn{sup +} implantation and postannealing result in (1) the formation of crystallographically orientated Zn nanocrystals in the ZnO matrix and (2) Mn atoms occupy the Zn sites in ZnO.

  6. Conductivity fluctuations in proton-implanted ZnO microwires.

    PubMed

    Dolgin, B; Lorite, I; Kumar, Y; Esquinazi, P; Jung, G; Straube, B; Heluani, S Perez de

    2016-07-29

    Electric noise can be an important limitation for applications of conducting elements in the nanometer size range. The intrinsic electrical noise of prospective materials for opto-spintronics applications like ZnO has not yet been characterized. In this study, we have investigated the conductivity fluctuations in 10 nm thick current paths produced by proton implantation of ZnO microwires at room temperature. The voltage noise under a constant dc current bias in undoped, as well as in Li-doped microwires, is characterized by [Formula: see text] power spectra with [Formula: see text]. The noise intensity scales with the square of the bias current pointing to bias-independent resistivity fluctuations as a source of the observed noise. The normalized power spectral density appears inversely proportional to the number of carriers in the probed sample volume, in agreement with the phenomenological Hooge law. For the proton-implanted ZnO microwire and at 1 Hz we obtain a normalized power spectral density as low as [Formula: see text] Hz(-1). PMID:27306486

  7. Conductivity fluctuations in proton-implanted ZnO microwires

    NASA Astrophysics Data System (ADS)

    Dolgin, B.; Lorite, I.; Kumar, Y.; Esquinazi, P.; Jung, G.; Straube, B.; Perez de Heluani, S.

    2016-07-01

    Electric noise can be an important limitation for applications of conducting elements in the nanometer size range. The intrinsic electrical noise of prospective materials for opto-spintronics applications like ZnO has not yet been characterized. In this study, we have investigated the conductivity fluctuations in 10 nm thick current paths produced by proton implantation of ZnO microwires at room temperature. The voltage noise under a constant dc current bias in undoped, as well as in Li-doped microwires, is characterized by 1/{f}a power spectra with a∼ 1. The noise intensity scales with the square of the bias current pointing to bias-independent resistivity fluctuations as a source of the observed noise. The normalized power spectral density appears inversely proportional to the number of carriers in the probed sample volume, in agreement with the phenomenological Hooge law. For the proton-implanted ZnO microwire and at 1 Hz we obtain a normalized power spectral density as low as ∼ {10}-11 Hz‑1.

  8. Amorphous clusters in Co implanted ZnO induced by boron pre-implantation

    SciTech Connect

    Potzger, K.; Shalimov, A.; Zhou, S.; Schmidt, H.; Mucklich, A.; Helm, M.; Fassbender, J.; Liberati, M.; Arenholz, E.

    2009-02-09

    We demonstrate the formation of superparamagnetic/ferromagnetic regions within ZnO(0001) single crystals sequently implanted with B and Co. While the pre-implantation with B plays a minor role for the electrical transport properties, its presence leads to the formation of amorphous phases. Moreover, B acts strongly reducing on the implanted Co. Thus, the origin of the ferromagnetic ordering in local clusters with large Co concentration is itinerant d-electrons as in the case of metallic Co. The metallic amorphous phases are non-detectable by common X-ray diffraction.

  9. Determination of Na acceptor level in Na+ ion-implanted ZnO single crystal

    NASA Astrophysics Data System (ADS)

    Wang, Zheng; Liu, Huibin; He, Haiping; Huang, Jingyun; Chen, Lingxiang; Ye, Zhizhen

    2015-03-01

    Ion implantation was used to dope Na acceptor into ZnO single crystals. With three mixed implantation energies, uniform depth distribution of Na ion in the surface region (~300 nm) of ZnO bulk crystals is achieved. Via post-implantation annealing, a donor-acceptor pair recombination band is identified in the low-temperature photoluminescence spectra, from which the energy level of Na-related acceptor in single crystalline ZnO is estimated to be 300 meV. A p-n junction based on this ZnO-Na layer shows rectifying characteristics, confirming the p-type conductivity.

  10. Effects of high-dose hydrogen implantation on defect formation and dopant diffusion in silver implanted ZnO crystals

    NASA Astrophysics Data System (ADS)

    Yaqoob, Faisal; Huang, Mengbing

    2016-07-01

    This work reports on the effects of a deep high-dose hydrogen ion implant on damage accumulation, defect retention, and silver diffusion in silver implanted ZnO crystals. Single-crystal ZnO samples were implanted with Ag ions in a region ˜150 nm within the surface, and some of these samples were additionally implanted with hydrogen ions to a dose of 2 × 1016 cm-2, close to the depth ˜250 nm. Rutherford backscattering/ion channeling measurements show that crystal damage caused by Ag ion implantation and the amount of defects retained in the near surface region following post-implantation annealing were found to diminish in the case with the H implantation. On the other hand, the additional H ion implantation resulted in a reduction of substitutional Ag atoms upon post-implantation annealing. Furthermore, the presence of H also modified the diffusion properties of Ag atoms in ZnO. We discuss these findings in the context of the effects of nano-cavities on formation and annihilation of point defects as well as on impurity diffusion and trapping in ZnO crystals.

  11. Synthesis of ZnO nanocrystals by subsequent implantation of Zn and O species

    SciTech Connect

    Lee, J.K.; Tewell, C.R.; Schulze, R.K.; Nastasi, M.; Hamby, D.W.; Lucca, D.A.; Jung, H.S.; Hong, K.S.

    2005-05-02

    We report the preparation of ZnO nanocrystals embedded in a SiO{sub 2} matrix formed using sequential zinc and oxygen ion implantations. The optical absorption spectra and photoemission spectra of zinc implanted and zinc/oxygen coimplanted silica show that the first zinc implantation produces zinc clusters and that the subsequent oxygen implantation following the zinc implantation rearranges the distribution of zinc and oxygen ions at an atomic level. While thermal annealing of Zn only implanted silica leads to the formation of Zn nanocrystals, thermal annealing of zinc/oxygen coimplanted silica promotes the growth of ZnO nanocrystals. The absorption and photoluminescence spectra show that ZnO nanocrystals form in an amorphous SiO{sub 2} matrix and that their systematic change as a function of annealing temperature corresponds to the typical correlation between the increase of particle size and a redshift in near-band-edge emission.

  12. Structural, electronic and magnetic properties of Er implanted ZnO thin films

    NASA Astrophysics Data System (ADS)

    Murmu, P. P.; Kennedy, J.; Ruck, B. J.; Leveneur, J.

    2015-09-01

    We report the structural, electronic and magnetic properties of Er implanted and annealed ZnO thin films. The effect of annealing in oxygen-deficient and oxygen-rich conditions was investigated. Rutherford backscattering spectrometry results revealed that the Er atoms are located at the implantation depth of around 13 nm, and annealing conditions had no adverse effect on the Er concentration in the layer. Raman spectroscopy results showed peak related to E2(high) mode of ZnO indicating enhanced crystalline quality of the Er implanted and annealed ZnO films. X-ray absorption near edge spectroscopy results demonstrated pre-edge features in O K-edge which are attributed to the structural defects in the films. Room temperature magnetic ordering was observed in Er implanted and annealed films, and is mainly assigned to the intrinsic defects in ZnO.

  13. Impurity-limited lattice disorder recovery in ion-implanted ZnO

    NASA Astrophysics Data System (ADS)

    Azarov, A. Yu.; Svensson, B. G.; Kuznetsov, A. Yu.

    2012-11-01

    The presence of implanted impurities can affect intrinsic defect annihilation or, in macroscopic terms, so-called lattice recovery, specifically in high dose implantation experiments typically applied to radiation hard materials, e.g., ZnO. Correlating diffusion and lattice recovery data, we demonstrate that F bombardment of ZnO results in a unique situation when implantation induced disorder anneals at anomalously low temperatures, specifically due to the F outdiffusion from the disordered region. Control F + B implants resulted in the suppression of F diffusion and stabilization of the lattice disorder providing the evidence for impurity-limited lattice recovery.

  14. Slow positron beam study of hydrogen ion implanted ZnO thin films

    NASA Astrophysics Data System (ADS)

    Hu, Yi; Xue, Xudong; Wu, Yichu

    2014-08-01

    The effects of hydrogen related defect on the microstructure and optical property of ZnO thin films were investigated by slow positron beam, in combination with x-ray diffraction, infrared and photoluminescence spectroscopy. The defects were introduced by 90 keV proton irradiation with doses of 1×1015 and 1×1016 ions cm-2. Zn vacancy and OH bonding (VZn+OH) defect complex were identified in hydrogen implanted ZnO film by positron annihilation and infrared spectroscopy. The formation of these complexes led to lattice disorder in hydrogen implanted ZnO film and suppressed the luminescence process.

  15. Effect of Thermal Annealing on the Characteristics of Phosphorus-Implanted ZnO Crystals

    NASA Astrophysics Data System (ADS)

    Jeong, T. S.; Yu, J. H.; Mo, H. S.; Kim, T. S.; Lim, K. Y.; Youn, C. J.; Hong, K. J.; Kim, H. S.

    2014-07-01

    A P-doped ZnO surface layer on undoped ZnO wafers was prepared by phosphorus (P) ion implantation. Hall effect measurement revealed p-type conduction in such layers annealed at 800°C. This indicates that acceptor levels are present in P-doped ZnO, even though the ZnO is still n-type. Micro-Raman scattering in - z( xy) z geometry was conducted on P-implanted ZnO. The E {2/high} mode shift observed toward the high-energy region was related to compressive stress as a result of P-ion implantation. This compressive stress led to the appearance of an A 1(LO) peak, which is an inactive mode. This A 1(LO) peak relaxed during thermal annealing in ambient oxygen at temperatures higher than 700°C. The P2p3/2 peak observed at 135.6 eV by x-ray photoelectron spectroscopy is associated with chemical bond formation leading to 2(P2O5) molecules. This indicates that implanted P ions substituted Zn sites in the ZnO layer. In photoluminescence spectroscopy, the P-related peaks observed at energies ranging between 3.1 and 3.5 eV originated from (A0, X) emission, because of PZn-2VZn complexes acting as shallow acceptors. The acceptor level was observed to be 126.9 meV above the valence band edge. Observation of this P-related emission indicates that ion implantation results in acceptor levels in the P-doped ZnO layer. This suggests that the P2O5 bonds are responsible for the p-type activity of P-implanted ZnO.

  16. Optical and electrical studies of ZnO thin films heavily implanted with silver ions

    NASA Astrophysics Data System (ADS)

    Lyadov, N. M.; Gumarov, A. I.; Valeev, V. F.; Nuzhdin, V. I.; Khaibullin, R. I.; Faizrakhmanov, I. A.

    2014-12-01

    Thin films of zinc oxide (ZnO) with the thickness of 200 nm have been deposited on quartz substrates by using ion-beam sputtering technique. Then Ag+ ions with the energy of 30 keV have been implanted into as-deposited ZnO films to the fluences in the range of (0.25-1.00)×1017 ions/cm2 to form ZnO:Ag composite layers with different concentrations of the silver impurity. The analysis of the microstructure has shown that the thickness of the ZnO film decreases, and the Ag dopant concentration tends to the saturation with increasing Ag implantation fluence. The ZnO:Ag composite layers reveal the optical selective absorption at the wavelength of the surface plasmon resonance that is typical for silver nanoparticles dispersed in the ZnO matrix. The red shift of the plasmon resonance peak from 480 to 500 nm is observed with the increase in the implantation fluence to 0.75×1017 Ag ions/cm2. Then the absorption peak position starts the backward motion, and the absorption intensity decreases with the subsequent increase in the implantation fluence. The non-monotonic dependence of the absorption peak position on the implantation fluence has been analyzed within of Maxwell Garnet theory and taking into account the strong sputtering of ZnO films during implantation. The ZnO:Ag composite layers exhibit the p-type conductivity indicating that a part of Ag+ ions is in the form of acceptor impurities implanted into the ZnO lattice.

  17. Local structural properties of Co-ion-implanted ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Park, C. I.; Jin, Zhenlan; Jeong, E. S.; Hwang, I. H.; Han, S. W.

    2013-12-01

    We examined the local structural properties around Co and Zn ions in Co-ion-implanted ZnO nanorods by using an X-ray absorption fine structure (XAFS) analysis. Vertically-aligned ZnO nanorods were synthesized on Al2O3 substrates by using a catalyst-free metal-organic chemicalvapor deposition. Co ions (Co+ and Co2+) with energies of 50 and 100 keV and fluxes of 1013 and 1015 particles/cm2 were implanted in the ZnO nanorods, and the ion-implanted ZnO nanorods were annealed at 400-650°C. X-ray absorption near edge structure (XANES) analyses demonstrated that the chemical valence state of the Co ions were mostly 2+. An extended XAFS (EXAFS) analysis revealed that the Co ions were mostly substituted at the Zn sites of ZnO nanorods at a Coion flux of 1015 particles/cm2. However, at a flux of 1013 particles/cm2, Co ions formed Co-O and Co-Co clusters. These results were in contrast to the Co distribution in Co-added ZnO predicted by using a Monte Carlo method.

  18. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    SciTech Connect

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-27

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 {mu}A mM{sup -1} cm{sup -2} and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

  19. Third generation biosensing matrix based on Fe-implanted ZnO thin film

    NASA Astrophysics Data System (ADS)

    Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

    2010-09-01

    Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 μA mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

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

    NASA Astrophysics Data System (ADS)

    Gunnlaugsson, H. P.; Bharuth-Ram, K.; Johnston, K.; Langouche, G.; Mantovan, R.; Mølholt, T. E.; Naidoo, D.; Ólafsson, O.; Weyer, G.

    2015-04-01

    57Fe Emission Mössbauer spectra obtained after low fluence (<1012 cm -2) implantation of 57Mn ( T 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 2+ and Fe 3+ on Zn sites, interstitial Fe and Fe in damage regions (Fe D ). The Fe D component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (˜1015 cm -2)57Fe/ 57Co implanted ZnO and 57Fe 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.

  1. Properties of nitrogen implanted and electron beam annealed bulk ZnO

    SciTech Connect

    Kennedy, J.; Carder, D. A.; Markwitz, A.; Reeves, R. J.

    2010-05-15

    The optical properties of bulk ZnO ion implanted with nitrogen ions, at an energy of 23 keV have been studied as a function of implantation fluence and electron beam (EB) annealing conditions. Nuclear reaction analysis and Raman results have revealed the implanted N concentration and its structural changes with respect to various nitrogen ion fluences. The optical properties of nitrogen implanted bulk ZnO were investigated by low temperature photoluminescence measurements. An enhanced peak at 3.235 eV has been attributed to donor-accepter pair (DAP) emission involving the implanted N acceptor in ZnO. The emission near 3.3085 eV is attributed to a free electron to acceptor transition. We also report a broad band emission feature at {approx}3.09 eV in the nitrogen implanted with 1-2x10{sup 15} ions cm{sup -2} and EB annealed at 800-900 deg. C. This is assigned to a thermally activated nitrogen acceptor transition as it is unique only to nitrogen implanted samples. An ionization energy of 377 meV indicates that this line may correspond to a significantly less shallow acceptor level. In addition an increase in the intensity and dominance of this DAP line in nitrogen implanted samples over the other acceptor transitions was observed with increasing annealing time and temperatures. It is shown that EB annealing offers a method of enhanced nitrogen activation when compared to a more conventional furnace approach.

  2. Deep-level emissions influenced by O and Zn implantations in ZnO

    NASA Astrophysics Data System (ADS)

    Zhao, Q. X.; Klason, P.; Willander, M.; Zhong, H. M.; Lu, W.; Yang, J. H.

    2005-11-01

    A set of bulk ZnO samples implanted with O and Zn at various densities were investigated by photoluminescence. The implantation concentration of O and Zn is varied between 1×1017/cm3 and 5×1019/cm3. The samples were thermally treated in an oxygen gas environment after the implantation. The results clearly show the influence of O and Zn implantations on the deep-level emission. By comparing the photoluminescence spectra for the samples with different implantations, we can conclude that the VZn is responsible to the observed deep-level emission. In addition, a novel transition at the emission energy of 3.08eV at 77K appears in the O-implanted sample with 5×1019/cm3 implantation concentration. The novel emission is tentatively identified as O-antisite OZn.

  3. Deep-level emissions influenced by O and Zn implantations in ZnO

    SciTech Connect

    Zhao, Q.X.; Klason, P.; Willander, M.; Zhong, H.M.; Lu, W.; Yang, J.H.

    2005-11-21

    A set of bulk ZnO samples implanted with O and Zn at various densities were investigated by photoluminescence. The implantation concentration of O and Zn is varied between 1x10{sup 17}/cm{sup 3} and 5x10{sup 19}/cm{sup 3}. The samples were thermally treated in an oxygen gas environment after the implantation. The results clearly show the influence of O and Zn implantations on the deep-level emission. By comparing the photoluminescence spectra for the samples with different implantations, we can conclude that the V{sub Zn} is responsible to the observed deep-level emission. In addition, a novel transition at the emission energy of 3.08 eV at 77 K appears in the O-implanted sample with 5x10{sup 19}/cm{sup 3} implantation concentration. The novel emission is tentatively identified as O-antisite O{sub Zn}.

  4. Ion Implantation in ZnO: Defect Interaction and Impurity Diffusion

    NASA Astrophysics Data System (ADS)

    Yaqoob, Faisal

    In the first part of this research we studied the entropy changes in diffusion prefactor and its effects on diffusion mechanisms and activation energies. We demonstrate a method based on ion implantation and Rutherford backscattering spectroscopy combined with ion channeling (RBS/C) to experimentally determine the diffusion properties of substitutional and interstitial diffusing atoms. The activation energies for each diffusing species are found to be in good agreement with those calculated in previous theoretical studies. The exponential prefactors of the measured diffusion coefficients vary by ten orders of magnitude among substitutional and interstitial diffusing species, allowing us to assign a specific diffusion mechanism to each type of diffusant according to both its diffusion energetics and entropic changes. In addition, the diffusion activation energies and the diffusivity prefactor for the four diffusing species studied are found to follow the Meyer--Neldel relationship with a characteristic excitation energy of ~ 92 meV in ZnO. In another important problem related to the p-doping difficulty in ZnO materials, we studied the effects of ion-implanted hydrogen ions on defect formation and impurity redistribution in ZnO crystals implanted with silver ions. Following Ag ion implantation, the damage level in the ZnO lattice was higher in the sample without H ion implantation than the sample with the H. We found that the damage created to oxygen lattice by the Ag atoms during implantation was higher than the damaged caused to the zinc lattice. Moreover, the Zn lattice recovered faster than the O lattice during thermal annealing. The Ag atoms have higher substitutional fraction in samples without H and increases with annealing temperature. In H implanted samples Ag and H is passivated in defect-related cluster, resulting lower activation of Ag. The diffusion process is affected by H implantation, making it difficult to diffuse to substitutional sites. We discuss

  5. Discrepancy between ambient annealing and H+ implantation in optical absorption of ZnO

    NASA Astrophysics Data System (ADS)

    Lv, Jinpeng; Li, Chundong

    2016-05-01

    The discrepancy between sub-bandgap absorption in ZnO induced by thermal annealing and H+ implantation is investigated in this study for the first time. Results indicate that nonreductive annealing-induced optical absorption is independent of annealing ambient, and can be assigned to VO, whereas the absorption centers caused by H+ implantation and H2 annealing are primarily associated with VO and ionized Zni.

  6. Ionoluminescence study of Zn- and O- implanted ZnO crystals: An additional perspective

    NASA Astrophysics Data System (ADS)

    Epie, E. N.; Chu, W. K.

    2016-05-01

    An investigation into the role of native point defects on the optical properties of ZnO using ion implantation, rapid thermal annealing (RTA) and ionoluminescence (IL) is presented. Low-energy (60 keV) fixed-fluence (8 × 1015 cm-2) Zn- and O- implantation has been used to directly introduce native point defects into ZnO single crystals. It is shown that annealing of implanted samples in Ar at T = 1000 °C for 2 min amplifies the deep band emission (DBE) peak centered around 2.4 eV while at the same time revealing subtle differences not clearly resolved in similar implanted samples treated under prolonged annealing. Particularly, a relative shift in the DBE peak maxima of the O and Zn doped samples subjected to RTA is observed. Gaussian decomposition of the IL spectra show distinct enhancements of the red (1.62 eV) and yellow (2.15 eV) emission bands in the O- implanted sample and the green (2.36 eV) emission band in the Zn- implanted sample. Based on these results, and recent density functional theory (DFT) calculations, we have proposed a possible energy level scheme for some common ZnO native point defects.

  7. NMR Observation of Mobile Protons in Proton-Implanted ZnO Nanorods

    NASA Astrophysics Data System (ADS)

    Park, Jun Kue; Kwon, Hyeok-Jung; Lee, Cheol Eui

    2016-03-01

    The diffusion properties of H+ in ZnO nanorods are investigated before and after 20 MeV proton beam irradiation by using 1H nuclear magnetic resonance (NMR) spectroscopy. Herein, we unambiguously observe that the implanted protons occupy thermally unstable site of ZnO, giving rise to a narrow NMR line at 4.1 ppm. The activation barrier of the implanted protons was found to be 0.46 eV by means of the rotating-frame spin-lattice relaxation measurements, apparently being interstitial hydrogens. High-energy beam irradiation also leads to correlated jump diffusion of the surface hydroxyl group of multiple lines at ~1 ppm, implying the presence of structural disorder at the ZnO surface.

  8. NMR Observation of Mobile Protons in Proton-Implanted ZnO Nanorods

    PubMed Central

    Park, Jun Kue; Kwon, Hyeok-Jung; Lee, Cheol Eui

    2016-01-01

    The diffusion properties of H+ in ZnO nanorods are investigated before and after 20 MeV proton beam irradiation by using 1H nuclear magnetic resonance (NMR) spectroscopy. Herein, we unambiguously observe that the implanted protons occupy thermally unstable site of ZnO, giving rise to a narrow NMR line at 4.1 ppm. The activation barrier of the implanted protons was found to be 0.46 eV by means of the rotating-frame spin-lattice relaxation measurements, apparently being interstitial hydrogens. High-energy beam irradiation also leads to correlated jump diffusion of the surface hydroxyl group of multiple lines at ~1 ppm, implying the presence of structural disorder at the ZnO surface. PMID:26988733

  9. Zn precipitation and Li depletion in Zn implanted ZnO

    NASA Astrophysics Data System (ADS)

    Chan, K. S.; Vines, L.; Li, L.; Jagadish, C.; Svensson, B. G.; Wong-Leung, J.

    2016-07-01

    Ion implantation of Zn substituting elements in ZnO has been shown to result in a dramatic Li depletion of several microns in hydrothermally grown ZnO. This has been ascribed to a burst of mobile Zn interstials. In this study, we seek to understand the reason behind this interstitial mediated transient enhanced diffusion in Li-containing ZnO samples after Zn implantation. ZnO wafers were implanted with Zn to two doses, 5 × 1015 cm-2 and 1 × 1017 cm-2. Secondary ion mass spectrometry was carried out to profile the Li depletion depth for different annealing temperatures between 600 and 800 °C. The 800 °C annealing had the most significant Li depletion of close to 60 μm. Transmission electron microscopy (TEM) was carried out in selected samples to identify the reason behind the Li depletion. In particular, TEM investigations of samples annealed at 750 °C show significant Zn precipitation just below the depth of the projected range of the implanted ions. We propose that the Zn precipitation is indicative of Zn supersaturation. Both the Li depletion and Zn precipitation are competing synchronous processes aimed at reducing the excess Zn interstitials.

  10. ZnO nanoparticles embedded in sapphire fabricated by ion implantation and annealing.

    PubMed

    Xiang, X; Zu, X T; Zhu, S; Wei, Q M; Zhang, C F; Sun, K; Wang, L M

    2006-05-28

    ZnO nanoparticles were fabricated in sapphire (α-Al(2)O(3) single crystal) by Zn ion implantation (48 keV) at an ion fluence of 1 × 10(17) cm(-2) and subsequent thermal annealing in a flowing oxygen atmosphere. Transmission electron microscopy (TEM) analysis revealed that metallic Zn nanoparticles of 3-10 nm in dimensions formed in the as-implanted sample and that ZnO nanoparticles of 10-12 nm in dimensions formed after annealing at 600 °C. A broad absorption band, peaked at 280 nm, appeared in the as-implanted crystal, due to surface plasma resonance (SPR) absorption of metallic Zn nanoparticles. After annealing at 600 °C, ZnO nanoparticles resulted in an exciton absorption peak at 360 nm. The photoluminescence (PL) of the as-implanted sample was very weak when using a He-Cd 325 nm line as the excitation source. However, two emission peaks appeared in the PL spectrum of ZnO nanopraticles, i.e., one ultraviolet (UV) peak at 370 nm and the other a green peak at 500 nm. The emission at 500 nm is stronger and has potential applications in green/blue light-emitting devices. PMID:21727517

  11. Towards p-type doping of ZnO by ion implantation

    SciTech Connect

    Coleman, V; Tan, H H; Jagadish, C; Kucheyev, S; Phillips, M; Zou, J

    2005-01-18

    Zinc oxide is a very attractive material for a range of optoelectronic devices including blue light-emitting diodes and laser diodes. Though n-type doping has been successfully achieved, p-type doing of ZnO is still a challenge that must be overcome before p-n junction devices can be realized. Ion implantation is widely used in the microelectronics industry for selective area doping and device isolation. Understanding damage accumulation and recrystallization processes is important for achieving selective area doping. In this study, As (potential p-type dopant) ion implantation and annealing studies were carried out. ZnO samples were implanted with high dose (1.4 x 10{sup 17} ions/cm{sup 2}) 300 keV As ions at room temperature. Furnace annealing of samples in the range of 900 C to 1200 C was employed to achieve recrystallization of amorphous layers and electrical activation of the dopant. Rutherford backscattering/channeling spectrometry, transmission electron microscopy and cathodolumiescence spectroscopy were used to monitor damage accumulation and annihilation behavior in ZnO. Results of this study have significant implications for p-type doing of ZnO by ion implantation.

  12. Study of the negative magneto-resistance of single proton-implanted lithium-doped ZnO microwires.

    PubMed

    Lorite, I; Zandalazini, C; Esquinazi, P; Spemann, D; Friedländer, S; Pöppl, A; Michalsky, T; Grundmann, M; Vogt, J; Meijer, J; Heluani, S P; Ohldag, H; Adeagbo, W A; Nayak, S K; Hergert, W; Ernst, A; Hoffmann, M

    2015-07-01

    The magneto-transport properties of single proton-implanted ZnO and of Li(7%)-doped ZnO microwires have been studied. The as-grown microwires were highly insulating and not magnetic. After proton implantation the Li(7%) doped ZnO microwires showed a non-monotonous behavior of the negative magneto-resistance (MR) at temperature above 150 K. This is in contrast to the monotonous NMR observed below 50 K for proton-implanted ZnO. The observed difference in the transport properties of the wires is related to the amount of stable Zn vacancies created at the near surface region by the proton implantation and Li doping. The magnetic field dependence of the resistance might be explained by the formation of a magnetic/non-magnetic heterostructure in the wire after proton implantation. PMID:26043764

  13. Study of the negative magneto-resistance of single proton-implanted lithium-doped ZnO microwires

    NASA Astrophysics Data System (ADS)

    Lorite, I.; Zandalazini, C.; Esquinazi, P.; Spemann, D.; Friedländer, S.; Pöppl, A.; Michalsky, T.; Grundmann, M.; Vogt, J.; Meijer, J.; Heluani, S. P.; Ohldag, H.; Adeagbo, W. A.; Nayak, S. K.; Hergert, W.; Ernst, A.; Hoffmann, M.

    2015-06-01

    The magneto-transport properties of single proton-implanted ZnO and of Li(7%)-doped ZnO microwires have been studied. The as-grown microwires were highly insulating and not magnetic. After proton implantation the Li(7%) doped ZnO microwires showed a non-monotonous behavior of the negative magneto-resistance (MR) at temperature above 150 K. This is in contrast to the monotonous NMR observed below 50 K for proton-implanted ZnO. The observed difference in the transport properties of the wires is related to the amount of stable Zn vacancies created at the near surface region by the proton implantation and Li doping. The magnetic field dependence of the resistance might be explained by the formation of a magnetic/non-magnetic heterostructure in the wire after proton implantation.

  14. Annealing of damage and stability of implanted ions in ZnO crystals

    SciTech Connect

    Sonder, E.; Zuhr, R.A.; Valiga, R.E.

    1988-08-01

    The annealing of Bi, Cr, and Mn, implanted in ZnO, has been studied by Rutherford backscattering, ion channeling, and secondary ion mass spectroscopy. Implantation of approx.10/sup 16/ ions/cm/sup 2/ of any of these elements produces large concentrations of Zn interstitials, but no completely amorphous region. The temperature at which these interstitials anneal is a function of the implant species. Other defects produced by the implantation, which give rise to dechanneling and a consequent increased scattering probability in the tails of backscattering spectra, anneal at significantly higher temperature. This annealing is also a function of the implant species. Motion of the implant ions themselves does not occur when the interstitials anneal; it takes place above 700 /sup 0/C for Bi and Mn, and above 1000 /sup 0/C for Cr.

  15. Damage formation and annealing at low temperatures in ion implanted ZnO

    SciTech Connect

    Lorenz, K.; Alves, E.; Wendler, E.; Bilani, O.; Wesch, W.; Hayes, M.

    2005-11-07

    N, Ar, and Er ions were implanted into ZnO at 15 K within a large fluence range. The Rutherford backscattering technique in the channeling mode was used to study in situ the damage built-up in the Zn sublattice at 15 K. Several stages in the damage formation were observed. From the linear increase of the damage for low implantation fluences, an upper limit of the Zn displacement energy of 65 eV could be estimated for [0001] oriented ZnO. Annealing measurements below room temperature show a significant recovery of the lattice starting at temperatures between 80 and 130 K for a sample implanted with low Er fluence. Samples with higher damage levels do not reveal any damage recovery up to room temperature, pointing to the formation of stable defect complexes.

  16. Luminescence and structural properties of defects in ion implanted ZnO

    NASA Astrophysics Data System (ADS)

    Monteiro, T.; Soares, M. J.; Neves, A. J.; Carmo, M. C.; Peres, M.; Cruz, A.; Alves, E.; Wahl, U.; Rita, E.; Munoz-Sanjose, V.; Zuniga-Perez, J.

    2006-03-01

    ZnO substrates and films were intentionally implanted with rare earth and transition metal ions. The influence of the implantation and subsequent air thermal annealing treatments on the structural and optical properties of ZnO samples were studied by using Rutherford backscattering spectrometry and low temperature photoluminescence techniques. Intraionic Tm-related emission was observed for bulk and ZnO films. Similarly, Eu and Tb-doped ZnO films follow the same trend observed in bulk samples. No intraionic related emission was observed for Eu-doped samples even being the ion in Zn sites and for the Tb-doped samples ion segregation was observed for thermal annealing temperatures above 800 °C. For the Mn-doped ZnO bulk samples the lattice recovery follows the same trend to that one observed for the Fe-doped samples, starting near 800 °C being fully recovered at 1050 °C. Although Fe3+ was observed no intraionic Mn-related emission was detected under the used conditions.

  17. Origins of low resistivity in Al ion-implanted ZnO bulk single crystals

    SciTech Connect

    Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2011-06-15

    The origins of low resistivity in Al ion-implanted ZnO bulk single crystals are studied by combining Rutherford backscattering spectroscopy (RBS), nuclear reaction analysis (NRA), photoluminescence (PL), and Van der Pauw methods. The Al-ion implantation (peak concentration: 2.6 x 10{sup 20}cm{sup -3}) into ZnO is performed using a multiple-step energy. The resistivity decreases from {approx}10{sup 4{Omega}} cm for un-implanted ZnO to 1.4 x 10{sup -1{Omega}} cm for as-implanted, and reaches 6.0 x 10{sup -4{Omega}} cm for samples annealed at 1000 deg. C. RBS and NRA measurements for as-implanted ZnO suggest the existence of the lattice displacement of Zn (Zn{sub i}) and O (O{sub i}), respectively. After annealing at 1000 deg. C, the Zn{sub i} related defects remain and the O{sub i} related defects disappear. The origin of the low resistivity in the as-implanted sample is attributed to the Zn{sub i} ({approx}30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]). In contrast, the origin of the low resistivity in the sample annealed at 1000 deg. C is assigned to both of the Zn{sub i} related defects and the electrically activated Al donor. A new PL emission appears at around 3.32 eV after annealing at 1000 deg. C, suggesting electrically activated Al donors.

  18. Equilibrium shape of nano-cavities in H implanted ZnO

    NASA Astrophysics Data System (ADS)

    Chan, K. S.; Vines, L.; Li, L.; Jagadish, C.; Svensson, B. G.; Wong-Leung, J.

    2015-05-01

    Thermally equilibrated nano-cavities are formed in ZnO by H implantation and subsequent high temperature annealing to determine the relative surface formation energies and step energies of ZnO from reverse Wulff construction and related analysis. H adsorption, vicinal surfaces, and surface polarity are found to play an important role in determining the final thermal equilibrium shape of the nano-cavities. Under H coverage, the O-terminated surface shows a significantly lower surface formation energy than the Zn-terminated surface.

  19. Gallium ion implantation greatly reduces thermal conductivity and enhances electronic one of ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Xia, Minggang; Cheng, Zhaofang; Han, Jinyun; Zheng, Minrui; Sow, Chorng-Haur; Thong, John T. L.; Zhang, Shengli; Li, Baowen

    2014-05-01

    The electrical and thermal conductivities are measured for individual zinc oxide (ZnO) nanowires with and without gallium ion (Ga+) implantation at room temperature. Our results show that Ga+ implantation enhances electrical conductivity by one order of magnitude from 1.01 × 103 Ω-1m-1 to 1.46 × 104 Ω-1m-1 and reduces its thermal conductivity by one order of magnitude from 12.7 Wm-1K-1 to 1.22 Wm-1K-1 for ZnO nanowires of 100 nm in diameter. The measured thermal conductivities are in good agreement with those in theoretical simulation. The increase of electrical conductivity origins in electron donor doping by Ga+ implantation and the decrease of thermal conductivity is due to the longitudinal and transverse acoustic phonons scattering by Ga+ point scattering. For pristine ZnO nanowires, the thermal conductivity decreases only two times when its diameter reduces from 100 nm to 46 nm. Therefore, Ga+-implantation may be a more effective method than diameter reduction in improving thermoelectric performance.

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

    PubMed

    Pereira, L M C; Wahl, U; Correia, J G; Van Bael, M J; Temst, K; Vantomme, A; Araújo, J P

    2013-10-16

    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 ° 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 K, irrespective of the Fe concentration and the density of beam-induced defects. With increasing local concentration of Zn-substitutional Fe, strong nearest-cation-neighbor antiferromagnetic interactions favor the antiparallel alignment of the Fe moments. PMID:24025311

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

    NASA Astrophysics Data System (ADS)

    Pereira, L. M. C.; Wahl, U.; Correia, J. G.; Van Bael, M. J.; Temst, K.; Vantomme, A.; Araújo, J. P.

    2013-10-01

    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 Zn1-xFexO 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 ° 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 K, irrespective of the Fe concentration and the density of beam-induced defects. With increasing local concentration of Zn-substitutional Fe, strong nearest-cation-neighbor antiferromagnetic interactions favor the antiparallel alignment of the Fe moments.

  2. Secondary phase segregation in heavily transition metal implanted ZnO

    SciTech Connect

    Schumm, Marcel; Koerdel, Martin; Geurts, Jean; Mueller, Sven; Ronning, Carsten; Dynowska, Elzbieta; Golacki, Zbigniew; Szuszkiewicz, Wojciech

    2009-04-15

    With micro-Raman spectroscopy and x-ray diffraction (XRD), we studied ZnO crystals implanted with Mn, Fe, Co, and Ni, respectively, with implantation concentrations from 4 up to 16 at. %. Using thermal treatments in air up to 700 deg. C, we analyzed the annealing effect on the ZnO crystal lattice as well as the onset of secondary phases and their microstructure on the sample surface. While the 500 deg. C treatment induces a considerable annealing, secondary phases are observed for transition metal (TM) concentrations >=8 at. % after the treatment at 700 deg. C. Their microstructure strongly depends on the TM species. Various stoichiometric and nonstoichiometric TM oxide precipitates as well as elemental TM clusters are identified by their Raman and XRD signatures and their possible magnetic impact is discussed.

  3. Effects of oxygen ion implantation in spray-pyrolyzed ZnO thin films

    NASA Astrophysics Data System (ADS)

    Vijayakumar, K. P.; Ratheesh Kumar, P. M.; Sudha Kartha, C.; Wilson, K. C.; Singh, F.; Nair, K. G. M.; Kashiwaba, Y.

    2006-04-01

    ZnO thin films, prepared using the chemical spray pyrolysis technique, were implanted using 100 keV O+ ions. Both pristine and ion-implanted samples were characterized using X-ray diffraction, optical absorption, electrical resistivity measurements, thermally stimulated current measurements and photoluminescence. Samples retained their crystallinity even after irradiation at a fluence of 1015 ions/cm2. However, at a still higher fluence of 2 × 1016 ions/cm2, the films became totally amorphous. The optical absorption edge remained unaffected by implantation and optical absorption spectra indicated two levels at 460 and 510 nm. These were attributed to defect levels corresponding to zinc vacancies (VZn) and oxygen antisites (OZn), respectively. Pristine samples had a broad photoluminescence emission centred at 517 nm, which was depleted on implantation. In the case of implanted samples, two additional emissions appeared at 425 and 590 nm. These levels were identified as due to zinc vacancies (VZn) and oxygen vacancies (VO), respectively. The electrical resistivity of implanted samples was much higher than that of pristine, while photosensitivity decreased to a very low value on implantation. This can be utilized in semiconductor device technology for interdevice isolation. Hall measurements showed a marked decrease in mobility due to ion implantation, while carrier concentration slightly increased.

  4. Rutherford backscattering and nuclear reaction analyses of hydrogen ion-implanted ZnO bulk single crystals

    NASA Astrophysics Data System (ADS)

    Kaida, T.; Kamioka, K.; Ida, T.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2014-08-01

    The origins of low resistivity in H ion-implanted ZnO bulk single crystals are studied by Rutherford backscattering spectrometry (RBS), nuclear reaction analysis (NRA) photoluminescence (PL), and Van der Pauw methods. The H-ion implantation (peak concentration: 1.45 × 1020 cm-3) into ZnO is performed using a 500 keV implanter. The resistivity decreases from 2.5 × 103 Ω cm for unimplanted ZnO to 6.5 Ω cm for as-implanted one. RBS measurements show that Zn interstitial as a shallow donor is not recognized in as-implanted samples. From photoluminescence measurements, the broad green band emission is observed in as-implanted samples. NRA measurements for as-implanted ZnO suggest the existence of the oxygen interstitial. The origins of the low resistivity in the as-implanted sample are attributed to both the H interstitial as a shallow donor and complex donor between H and disordered O. The activation energy of H related donors estimated from the temperature dependence of carrier concentration is 29 meV.

  5. Dynamic hyperfine interactions in 111In(111Cd)-doped ZnO semiconductor: PAC results supported by ab initio calculations

    NASA Astrophysics Data System (ADS)

    Muñoz, Emiliano L.; Mercurio, Marcio E.; Cordeiro, Moacir R.; Pereira, Luciano F. D.; Carbonari, Artur W.; Rentería, Mario

    2012-08-01

    In this work, we present results of Time-Differential γ-γ Perturbed-Angular-Correlations (PAC) experiments performed in 111Cd-doped ZnO semiconductor. The PAC technique has been applied in order to characterize the electric-field-gradient (EFG) tensor at (111In (EC)→) 111Cd nuclei located, as was later demonstrated, at defect-free cation sites of the ZnO host structure. The PAC experiments were performed in the temperature range of 77-1075 K. At first glance, the unexpected presence of low-intensity dynamic hyperfine interactions was observed, which were analyzed with a perturbation factor based on the Bäverstam and Othaz model. The experimental EFG results were compared with ab initio calculations performed with the Full-Potential Augmented Plane Wave plus local orbital (FP-APW+lo) method, in the framework of the Density Functional Theory (DFT), using the Wien2K code. The presence of the dynamic hyperfine interactions has been analyzed enlightened by the FP-APW+lo calculations of the EFG performed as a function of the charge state of the cell. We could correlate the large strength of the dynamic hyperfine interaction with the strong variation of the EFG due to changes in the electronic charge distribution in the Cd vicinity during the time-window of the PAC measurement. It was also revealed that the Cd impurity decays to a final stable neutral charge state (Cd2+) fast enough (in few ns) to produce the nearly undamped observed PAC spectra.

  6. Intrinsic Point-Defect Balance in Self-Ion-Implanted ZnO

    NASA Astrophysics Data System (ADS)

    Neuvonen, Pekka T.; Vines, Lasse; Svensson, Bengt G.; Kuznetsov, Andrej Yu.

    2013-01-01

    The role of excess intrinsic atoms for residual point defect balance has been discriminated by implanting Zn or O ions into Li-containing ZnO and monitoring Li redistribution and electrical resistivity after postimplant anneals. Strongly Li-depleted regions were detected in the Zn-implanted samples at depths beyond the projected range (Rp) upon annealing ≥600°C, correlating with a resistivity decrease. In contrast, similar anneals of the O-implanted samples resulted in Li accumulation at Rp and an increased resistivity. Control samples implanted with Ar or Ne ions, yielding similar defect production as for the Zn or O implants but with no surplus of intrinsic atoms, revealed no Li depletion. Thus, the depletion of Li shows evidence of excess Zn interstitials (ZnI) being released during annealing of the Zn-implanted samples. These ZnI’s convert substitutional Li atoms (LiZn) into highly mobile interstitial ones leading to the strongly Li-depleted regions. In the O-implanted samples, the high resistivity provides evidence of stable OI-related acceptors.

  7. A study of the structural and magnetic properties of ZnO implanted by Gd ions

    NASA Astrophysics Data System (ADS)

    Macková, A.; Malinský, P.; Sofer, Z.; Šimek, P.; Sedmidubský, D.; Mikulics, M.; Wilhelm, R. A.

    2014-08-01

    The structural and magnetic properties of ZnO (0 0 0 1) single crystals implanted with 200 keV Gd ions up to a fluence of 5 × 1015 cm-2 and subsequently annealed at 800 °C in various atmospheres were studied. The chemical composition and concentration depth profiles of ion-implanted layers were characterised by Rutherford Back-Scattering spectrometry (RBS) and compared to SRIM simulations. The as-implanted Gd depth profiles were found to be broader than those simulated by SRIM, but the projected range coincided well with that simulated. After annealing at 800 °C, the depth profiles became narrower. The structural changes in the layers modified by ion implantation and subsequent annealing were characterised by RBS channelling. The annealing led to partial recrystallisation and a decrease in the number of Gd atoms situated in substitutional positions. Raman spectroscopy showed that the point defects in Zn and O vacancies had been created by implantation and that these defects are most effectively cured after annealing in oxygen atmosphere. AFM analysis was used to determine the surface-morphology changes after the implantation and annealing procedures. The as-implanted samples exhibited ferromagnetism persisting up to room temperature. The annealing procedure led to paramagnetic behaviour, probably caused by the formation of gadolinium clusters.

  8. Silver migration and trapping in ion implanted ZnO single crystals

    NASA Astrophysics Data System (ADS)

    Azarov, Alexander; Vines, Lasse; Rauwel, Protima; Monakhov, Edouard; Svensson, Bengt G.

    2016-05-01

    Potentially, group-Ib elements (Cu, Ag, and Au) incorporated on Zn sites can be used for p-type doping of ZnO, and in the present paper, we use ion implantation to introduce Ag atoms in wurtzite ZnO single crystals. Monitoring the Li behavior, being a residual impurity in the crystals, as a tracer, we demonstrate that Zn interstitials assist the Ag diffusion and lead to Ag pile-up behind the implanted region after annealing above 800 °C. At even higher temperatures, a pronounced Ag loss from the sample surface occurs and concurrently the Ag atoms exhibit a trap-limited diffusion into the crystal bulk with an activation energy of ˜2.6 eV. The dominant traps are most likely Zn vacancies and substitutional Li atoms, yielding substitutional Ag atoms. In addition, formation of an anomalous multipeak Ag distribution in the implanted near-surface region after annealing can be attributed to local implantation-induced stoichiometry disturbances leading to trapping of the Ag atoms by O and Zn vacancies in the vicinity of the surface and in the end-of-range region, respectively.

  9. Compositional and Structural Study of Gd Implanted ZnO Films

    SciTech Connect

    Murmu, Peter P.; Kennedy, John V.; Markwitz, Andreas; Ruck, Ben J.

    2009-07-23

    We report a compositional and structural study of ZnO films implanted with 30 keV Gd ions. The depth profile of the implanted ions, measured by Rutherford backscattering spectrometry, matches predictions of DYNAMIC-TRIM calculations. However, after annealing at temperatures above 550 deg. C the Gd ions are observed to migrate towards the bulk, and at the same time atomic force microscope images of the film surfaces show significant roughening. Raman spectroscopy shows that the annealed films have a reduced number of crystalline defects. The overall results are useful for developing an implantation-annealing regime to produce well characterized samples to investigate magnetism in the ZnO:Gd system.

  10. Electrical, optical, photocatalytic, and bactericidal properties of polyethylene glycol-assisted sol-gel synthesized ZnTiO3-implanted ZnO nanoparticles

    NASA Astrophysics Data System (ADS)

    Karunakaran, Chockalingam; Vinayagamoorthy, Pazhamalai; Jayabharathi, Jayaraman

    2014-12-01

    ZnTiO3-implanted ZnO nanoparticles were prepared by sol-gel method employing polyethylene glycol (PEG) 4000 and 20 000. The high resolution transmission electron micrographs, selected area electron diffraction pattern, energy dispersive x-ray spectra and powder x-ray diffractograms show the prepared materials as core/shell nanoparticles. Increase of the molecular mass of PEG decreases the d-spacing in ZnO of ZnTiO3-implanted ZnO and pristine ZnO nanoparticles. The charge transfer resistances of ZnTiO3-implanted ZnO nanoparticles are larger than those of pristine ZnO and precursor ZnTiO3 nanoparticles. The optical properties of ZnTiO3/ZnO nanoparticles are similar to those of pristine ZnO nanoparticles. The photocatalytic activity of ZnO is enhanced by the presence of ZnTiO3 core in the ZnO lattice. The bactericidal activity of core/shell ZnTiO3/ZnO nanoparticles is not less than that of ZnO nanoparticles.

  11. Lattice location and thermal stability of implanted Fe in ZnO

    SciTech Connect

    Rita, E.; Wahl, U.; Correia, J.G.; Alves, E.; Soares, J.C.

    2004-11-22

    The emission channeling technique was applied to evaluate the lattice location of implanted {sup 59}Fe in single-crystalline ZnO. The angular distribution of {beta}{sup -} particles emitted by {sup 59}Fe was monitored with a position-sensitive electron detector, following 60 keV low dose (2.0x10{sup 13} cm{sup -2}) room-temperature implantation of the precursor isotope {sup 59}Mn. The emission patterns around the [0001], [1102],[1101], and [2113] directions revealed that following annealing at 800 deg. C, 95(8)% of the Fe atoms occupy ideal substitutional Zn sites with rms displacements of 0.06-0.09 A.

  12. Effect of implanted species on thermal evolution of ion-induced defects in ZnO

    SciTech Connect

    Azarov, A. Yu.; Rauwel, P.; Kuznetsov, A. Yu.; Svensson, B. G.; Hallén, A.; Du, X. L.

    2014-02-21

    Implanted atoms can affect the evolution of ion-induced defects in radiation hard materials exhibiting a high dynamic annealing and these processes are poorly understood. Here, we study the thermal evolution of structural defects in wurtzite ZnO samples implanted at room temperature with a wide range of ion species (from {sup 11}B to {sup 209}Bi) to ion doses up to 2 × 10{sup 16} cm{sup −2}. The structural disorder was characterized by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis, and transmission electron microscopy, while secondary ion mass spectrometry was used to monitor the behavior of both the implanted elements and residual impurities, such as Li. The results show that the damage formation and its thermal evolution strongly depend on the ion species. In particular, for F implanted samples, a strong out-diffusion of the implanted ions results in an efficient crystal recovery already at 600 °C, while co-implantation with B (via BF{sub 2}) ions suppresses both the F out-diffusion and the lattice recovery at such low temperatures. The damage produced by heavy ions (such as Cd, Au, and Bi) exhibits a two-stage annealing behavior where efficient removal of point defects and small defect clusters occurs at temperatures ∼500 °C, while the second stage is characterized by a gradual and partial annealing of extended defects. These defects can persist even after treatment at 900 °C. In contrast, the defects produced by light and medium mass ions (O, B, and Zn) exhibit a more gradual annealing with increasing temperature without distinct stages. In addition, effects of the implanted species may lead to a nontrivial defect evolution during the annealing, with N, Ag, and Er as prime examples. In general, the obtained results are interpreted in terms of formation of different dopant-defect complexes and their thermal stability.

  13. Effect of implanted species on thermal evolution of ion-induced defects in ZnO

    NASA Astrophysics Data System (ADS)

    Azarov, A. Yu.; Hallén, A.; Du, X. L.; Rauwel, P.; Kuznetsov, A. Yu.; Svensson, B. G.

    2014-02-01

    Implanted atoms can affect the evolution of ion-induced defects in radiation hard materials exhibiting a high dynamic annealing and these processes are poorly understood. Here, we study the thermal evolution of structural defects in wurtzite ZnO samples implanted at room temperature with a wide range of ion species (from 11B to 209Bi) to ion doses up to 2 × 1016 cm-2. The structural disorder was characterized by a combination of Rutherford backscattering spectrometry, nuclear reaction analysis, and transmission electron microscopy, while secondary ion mass spectrometry was used to monitor the behavior of both the implanted elements and residual impurities, such as Li. The results show that the damage formation and its thermal evolution strongly depend on the ion species. In particular, for F implanted samples, a strong out-diffusion of the implanted ions results in an efficient crystal recovery already at 600 °C, while co-implantation with B (via BF2) ions suppresses both the F out-diffusion and the lattice recovery at such low temperatures. The damage produced by heavy ions (such as Cd, Au, and Bi) exhibits a two-stage annealing behavior where efficient removal of point defects and small defect clusters occurs at temperatures ˜500 °C, while the second stage is characterized by a gradual and partial annealing of extended defects. These defects can persist even after treatment at 900 °C. In contrast, the defects produced by light and medium mass ions (O, B, and Zn) exhibit a more gradual annealing with increasing temperature without distinct stages. In addition, effects of the implanted species may lead to a nontrivial defect evolution during the annealing, with N, Ag, and Er as prime examples. In general, the obtained results are interpreted in terms of formation of different dopant-defect complexes and their thermal stability.

  14. Tunable transport properties of n-type ZnO nanowires by Ti plasma immersion ion implantation

    SciTech Connect

    Liao, L.; Zhang, Z.; Yan, B.; Li, G. P.; Wu, T.; Shen, Z. X.; Yu, T.; Yang, Y.; Cao, H. T.; Chen, L. L.; Tay, B. K.; Sun, X. W.

    2008-10-01

    Single-crystalline, transparent conducting ZnO nanowires were obtained simply by Ti plasma immersion ion implantation (PIII). Electrical transport characterizations demonstrate that the n-type conduction of ZnO nanowire could be tuned by appropriate Ti-PIII. When the energy of PIII is increased, the resistivity of ZnO decreases from 4x10{sup 2} to 3.3x10{sup -3} {omega} cm, indicating a semiconductor-metal transition. The failure-current densities of the metallic ZnO could be up to 2.75x10{sup 7} A/cm{sup 2}. Therefore, this facile method may provide an inexpensive alternative to tin doped indium oxide as transparent conducting oxide materials.

  15. Fabrication of ZnO nanoparticles in SiO{sub 2} by ion implantation combined with thermal oxidation

    SciTech Connect

    Amekura, H.; Umeda, N.; Sakuma, Y.; Kishimoto, N.; Buchal, Ch.

    2005-07-04

    Zinc-oxide (ZnO) nanoparticles (NPs) are fabricated in silica glasses (SiO{sub 2}) by implantation of Zn{sup +} ions of 60 keV up to 1.0x10{sup 17} ions/cm{sup 2} and following thermal oxidation. After the oxidation at 700 deg. C for 1 h, the absorption in the visible region due to Zn metallic NPs disappears and a new absorption edge due to ZnO appears at {approx}3.25 eV. Cross-sectional transmission electron microscopy confirms the formation of ZnO NPs of 5-10 nm in diameter within the near-surface region of {approx}80 nm thick and larger ZnO NPs on the surface. Under He-Cd laser excitation at {lambda}=325 nm, an exciton luminescence peak centered at 375 nm with FWHM of 113 meV was observed at room temperature.

  16. Single phase formation of Co-implanted ZnO thin films by swift heavy ion irradiation: Optical studies

    SciTech Connect

    Kumar, Ravi; Singh, Fouran; Angadi, Basavaraj; Choi, Ji-Won; Choi, Won-Kook; Jeong, Kwangho; Song, Jong-Han; Khan, M. Wasi; Srivastava, J. P.; Kumar, Ajay; Tandon, R. P.

    2006-12-01

    Low temperature photoluminescence and optical absorption studies on 200 MeV Ag{sup +15} ion irradiated Co-implanted ZnO thin films were studied. The Co clusters present in as implanted samples were observed to be dissolved using 200 MeV Ag{sup +15} ion irradiation with a fluence of 1x10{sup 12} ions/cm{sup 2}. The photoluminescence spectrum of pure ZnO thin film was characterized by the I{sub 4} peak due to the neutral donor bound excitons and the broad green emission. The Co-doped ZnO films show three sharp levels and two shoulders corresponding to 3t{sub 2g} and 2e{sub g} levels of crystal field splitted Co d orbitals, respectively. The ultraviolet-visible absorption spectroscopy also shows the systematic variation of band gap after 200 MeV Ag{sup +15} ion irradiation.

  17. Tuning quantum corrections and magnetoresistance in ZnO nanowires by ion implantation.

    PubMed

    Zeng, Y J; Pereira, L M C; Menghini, M; Temst, K; Vantomme, A; Locquet, J-P; Van Haesendonck, C

    2012-02-01

    Using ion implantation, the electrical as well as the magnetotransport properties of individual ZnO nanowires (NWs) can be tuned. The virgin NWs are configured as field-effect transistors which are in the enhancement mode. Al-implanted NWs reveal a three-dimensional metallic-like behavior, for which the magnetoresistance is well described by a semiempirical model that takes into account the presence of doping induced local magnetic moments and of two conduction bands. On the other hand, one-dimensional electron transport is observed in Co-implanted NWs. At low magnetic fields, the anisotropic magnetoresistance can be described in the framework of weak electron localization in the presence of strong spin-orbit scattering. From the weak localization, a large phase coherence length is inferred that reaches up to 800 nm at 2.5 K. The temperature-dependent dephasing is shown to result from a one-dimensional Nyquist noise-related mechanism. At the lowest temperatures, the phase coherence length becomes limited by magnetic scattering. PMID:22214218

  18. Crucial role of implanted atoms on dynamic defect annealing in ZnO

    SciTech Connect

    Azarov, A. Yu.; Kuznetsov, A. Yu.; Svensson, B. G.; Wendler, E.

    2014-02-03

    Processes of defect formation in radiation hard semiconductors exhibiting efficient dynamic annealing are different from those in amorphizible ones, and the latter are generally more well-studied. In the present work, we investigate structural disorder in wurtzite ZnO, which is a radiation hard material, implanted with different ions at room temperature and 15 K. The sample analysis was undertaken by Rutherford backscattering/channeling spectrometry performed in-situ without changing the sample temperature. The fluence dependence of bulk disorder exhibits the so-called IV-stage evolution, where the high fluence regime is characterized by both a strong influence on the damage build-up by the ion type and a reverse temperature effect. A straightforward methodology is demonstrated to differentiate between the contributions of pure ballistic and ion-defect reaction processes in the damage formation.

  19. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO -- a phenomenon related to defects?

    SciTech Connect

    Arenholz, Elke; Zhou, S.; Potzger, K.; Talut, G.; Reuther, H.; Kuepper, K.; Grenzer, J.; Xu, Q.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.

    2008-03-12

    We investigated ZnO(0001) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction.

  20. Characteristic properties of Raman scattering and photoluminescence on ZnO crystals doped through phosphorous-ion implantation

    SciTech Connect

    Jeong, T. S.; Yu, J. H.; Mo, H. S.; Kim, T. S.; Lim, K. Y.; Youn, C. J.; Hong, K. J.

    2014-02-07

    P-doped ZnO was fabricated by means of the ion-implantation method. At the Raman measurement, the blue shift of the E{sub 2}{sup high} mode and A{sub 1}(LO) phonon of the inactive mode were observed after the P-ion implantation. It suggested to be caused by the compressive stress. Thus, Hall effect measurement indicates that the acceptor levels exists in P-doped ZnO while still maintaining n-type ZnO. From the X-ray photoelectron spectroscopy, the chemical bond formation of the P2p{sub 3/2} spectrum consisted of 2(P{sub 2}O{sub 5}) molecules. Therefore, the implanted P ions were substituted to the Zn site in ZnO. From the photoluminescence (PL) spectra, P-related PL peaks were observed in the energy ranges of 3.1 and 3.5 eV, and its origin was analyzed at P{sub Zn}-2V{sub Zn} complexes, acting as a shallow acceptor. With increasing temperatures, the neutral-acceptor bound-exciton emission, (A{sup 0}, X), shows a tendency to quench the intensity and extend the emission linewidth. From the relations of the intensity and the linewidth as a function of temperature, the broadening of linewidth was believed to the result that the vibration mode of E{sub 2}{sup high} participates in the broadening process of (A{sup 0}, X) and the change of luminescent intensity was attributed to the partial dissociation of (A{sup 0}, X). Consequently, these facts indicate that the acceptor levels existed in P-doped ZnO layer by the ion implantation.

  1. Characteristic properties of Raman scattering and photoluminescence on ZnO crystals doped through phosphorous-ion implantation

    NASA Astrophysics Data System (ADS)

    Jeong, T. S.; Yu, J. H.; Mo, H. S.; Kim, T. S.; Lim, K. Y.; Youn, C. J.; Hong, K. J.

    2014-02-01

    P-doped ZnO was fabricated by means of the ion-implantation method. At the Raman measurement, the blue shift of the E2high mode and A1(LO) phonon of the inactive mode were observed after the P-ion implantation. It suggested to be caused by the compressive stress. Thus, Hall effect measurement indicates that the acceptor levels exists in P-doped ZnO while still maintaining n-type ZnO. From the X-ray photoelectron spectroscopy, the chemical bond formation of the P2p3/2 spectrum consisted of 2(P2O5) molecules. Therefore, the implanted P ions were substituted to the Zn site in ZnO. From the photoluminescence (PL) spectra, P-related PL peaks were observed in the energy ranges of 3.1 and 3.5 eV, and its origin was analyzed at PZn-2VZn complexes, acting as a shallow acceptor. With increasing temperatures, the neutral-acceptor bound-exciton emission, (A0, X), shows a tendency to quench the intensity and extend the emission linewidth. From the relations of the intensity and the linewidth as a function of temperature, the broadening of linewidth was believed to the result that the vibration mode of E2high participates in the broadening process of (A0, X) and the change of luminescent intensity was attributed to the partial dissociation of (A0, X). Consequently, these facts indicate that the acceptor levels existed in P-doped ZnO layer by the ion implantation.

  2. Embedment of ZnO nanoparticles in SiO{sub 2} by ion implantation and low-temperature oxidation

    SciTech Connect

    Amekura, H.; Umeda, N.; Boldyryeva, H.; Kishimoto, N.; Buchal, Ch.; Mantl, S.

    2007-02-19

    Samples of silica glass (SiO{sub 2}) implanted with 60 keV Zn ions to a fluence of 1.0x10{sup 17} ions/cm{sup 2} were annealed in oxygen gas to form ZnO nanoparticles (NPs). Although the ZnO NPs were formed mainly on the SiO{sub 2} surface after oxidation at 700 deg. C for 1 h, they were formed inside the SiO{sub 2} substrate after lower temperature and long-duration oxidation at 500 deg. C for {approx}70 h, i.e., the embedment of ZnO NPs in SiO{sub 2} was attained. The embedded NPs show a slightly stronger exciton peak and much weaker defect luminescence than the NPs formed on the surface.

  3. Optical activity and defect/dopant evolution in ZnO implanted with Er

    SciTech Connect

    Azarov, Alexander; Galeckas, Augustinas; Kuznetsov, Andrej; Monakhov, Edouard; Svensson, Bengt G.; Hallén, Anders

    2015-09-28

    The effects of annealing on the optical properties and defect/dopant evolution in wurtzite (0001) ZnO single crystals implanted with Er ions are studied using a combination of Rutherford backscattering/channeling spectrometry and photoluminescence measurements. The results suggest a lattice recovery behavior dependent on ion dose and involving formation/evolution of an anomalous multipeak defect distribution, thermal stability of optically active Er complexes, and Er outdiffusion. An intermediate defect band occurring between the surface and ion-induced defects in the bulk is stable up to 900 °C and has a photoluminescence signature around 420 nm well corresponding to Zn interstitials. The optical activity of the Er atoms reaches a maximum after annealing at 700 °C but is not directly associated to the ideal Zn site configuration, since the Er substitutional fraction is maximal already in the as-implanted state. In its turn, annealing at temperatures above 700 °C leads to dissociation of the optically active Er complexes with subsequent outdiffusion of Er accompanied by the efficient lattice recovery.

  4. Optical activity and defect/dopant evolution in ZnO implanted with Er

    NASA Astrophysics Data System (ADS)

    Azarov, Alexander; Galeckas, Augustinas; Hallén, Anders; Kuznetsov, Andrej; Monakhov, Edouard; Svensson, Bengt G.

    2015-09-01

    The effects of annealing on the optical properties and defect/dopant evolution in wurtzite (0001) ZnO single crystals implanted with Er ions are studied using a combination of Rutherford backscattering/channeling spectrometry and photoluminescence measurements. The results suggest a lattice recovery behavior dependent on ion dose and involving formation/evolution of an anomalous multipeak defect distribution, thermal stability of optically active Er complexes, and Er outdiffusion. An intermediate defect band occurring between the surface and ion-induced defects in the bulk is stable up to 900 °C and has a photoluminescence signature around 420 nm well corresponding to Zn interstitials. The optical activity of the Er atoms reaches a maximum after annealing at 700 °C but is not directly associated to the ideal Zn site configuration, since the Er substitutional fraction is maximal already in the as-implanted state. In its turn, annealing at temperatures above 700 °C leads to dissociation of the optically active Er complexes with subsequent outdiffusion of Er accompanied by the efficient lattice recovery.

  5. Nuclear reaction analysis of Ge ion-implanted ZnO bulk single crystals: The evaluation of the displacement in oxygen lattices

    NASA Astrophysics Data System (ADS)

    Kamioka, K.; Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2014-08-01

    The displacement of oxygen lattices in Ge ion-implanted ZnO bulk single crystals is studied by nuclear reaction analysis (NAR), photoluminescence (PL), and Van der Pauw methods. The Ge ion-implantation (net concentration: 2.6 × 1020 cm-3) into ZnO is performed using a multiple-step energy. The high resistivity of ∼103 Ω cm in un-implanted samples remarkably decreased to ∼10-2 Ω cm after implanting Ge-ion and annealing subsequently. NRA measurements of as-implanted and annealed samples suggest the existence of the lattice displacement of O atoms acting as acceptor defects. As O related defects still remain after annealing, these defects are not attributed to the origin of the low resistivity in 800 and 1000 °C annealed ZnO.

  6. Two shallow donors related to Zn interstitial in S-ion implanted ZnO epitaxial film

    NASA Astrophysics Data System (ADS)

    Kamioka, K.; Kuriyama, K.; Kushida, K.

    2014-06-01

    Two shallow donors are observed in sulfur-ion implanted ZnO epitaxial films on sapphire substrates. The resistivity varies from ~103 Ω cm for un-implanted samples to 1.7×10-2 Ω cm for as-implanted ones. This low resistivity is attributed to zinc interstitial (Zni), corresponding to the activation energy (26 meV) estimated from the temperature dependence of electron concentration. The presence of Zni is evaluated from ion channeling by Rutherford backscattering spectroscopy. The disordered concentration is ~40% of Zn atoms at a maximum point (300 nm) from the surface in as-implanted samples and recovers to ~80% after 1000 °C annealing. In 1000 °C annealed samples, a shallower donor level of 12 meV is observed, suggesting the presence of complex defects consisting of remaining Zni and sulfur atoms replaced to the oxygen atom.

  7. Depth Profiling of N and C in Ion Implanted ZnO and Si Using Deuterium Induced Nuclear Reaction Analysis

    SciTech Connect

    Kennedy, John; Murmu, Peter; Markwitz, Andreas

    2008-11-03

    Nuclear Reaction Analysis (NRA) with deuteron ion beams has been used to probe for ion implanted nitrogen and carbon with high sensitivity in zinc oxide and silicon single crystals. The ion implanted N was measured using 1.4 MeV deuteron ion beams and was found to be in agreement with calculated values. The limit of detection for N in ZnO is 8x10{sup 14} ions cm{sup -2}. Raman measurements of the ion implanted samples showed three additional modes at 275, 504, and 644 cm{sup -1} compared to the un-implanted ZnO crystals. The NRA and Raman results provided information on the N concentration, depth distribution, and structural changes that occur in dependence on the nitrogen ion fluences. The deuterium induced {sup 12}C(d,p){sup 13}C reaction was used to measure the carbon impurity/dose in ion implanted silicon. It was found that the use of a large cold shield (liquid nitrogen trap) in the ion implanter chamber greatly reduces the amount of carbon impurity on the surface of ion implanted silicon. Various implantations with N{sub 2}, O{sub 2}, NO, NO{sub 2} and Pb ions were performed with and without cooling of the liquid nitrogen trap. Simultaneous detection of ppm-level concentrations of {sup 12}C, {sup 16}O and {sup 14}N enables highly sensitive measurement of impurities that may be incorporated during the fabrication process, transport of the samples and/or storage of the samples in air.

  8. Origins of low resistivity and Ge donor level in Ge ion-implanted ZnO bulk single crystals

    SciTech Connect

    Kamioka, K.; Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.

    2013-12-04

    The energy level of Ge in Ge-ion implanted ZnO single crystals is studied by Hall-effect and photoluminescence (PL) methods. The variations in resistivity from ∼10{sup 3} Ωcm for un-implanted samples to ∼10{sup −2} Ωcm for as-implanted ones are observed. The resistivity is further decreased to ∼10{sup −3} Ωcm by annealing. The origins of the low resistivity are attributed to both the zinc interstitial (Zn{sub i}) related defects and the electrical activated Ge donor. An activation energy of Ge donors estimated from the temperature dependence of carrier concentration is 102 meV. In PL studies, the new peak at 372 nm (3.33 eV) related to the Ge donor is observed in 1000 °C annealed samples.

  9. Origins of low resistivity and Ge donor level in Ge ion-implanted ZnO bulk single crystals

    NASA Astrophysics Data System (ADS)

    Kamioka, K.; Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.

    2013-12-01

    The energy level of Ge in Ge-ion implanted ZnO single crystals is studied by Hall-effect and photoluminescence (PL) methods. The variations in resistivity from ˜103 Ωcm for un-implanted samples to ˜10-2 Ωcm for as-implanted ones are observed. The resistivity is further decreased to ˜10-3 Ωcm by annealing. The origins of the low resistivity are attributed to both the zinc interstitial (Zni) related defects and the electrical activated Ge donor. An activation energy of Ge donors estimated from the temperature dependence of carrier concentration is 102 meV. In PL studies, the new peak at 372 nm (3.33 eV) related to the Ge donor is observed in 1000 °C annealed samples.

  10. Controlling the growth of ZnO quantum dots embedded in silica by Zn/F sequential ion implantation and subsequent annealing.

    PubMed

    Ren, F; Zhang, L Y; Xiao, X H; Cai, G X; Fan, L X; Liao, L; Jiang, C Z

    2008-04-16

    We report the formation of embedded ZnO quantum dots (QDs) by Zn and F ion sequential implantation and subsequent annealing. Optical absorption and photoluminescence spectrum measurements, transmission electron microscopy bright field images and selected area electron diffraction patterns indicate that ZnO QDs were formed after annealing in air or vacuum at temperatures higher than 500 °C. Atomic force microscopy images show a comparatively flat surface of the annealed samples, which indicates that only very few Zn atoms are evaporated to the surfaces. The formation of ZnO QDs during the thermal annealing can be attributed to the direct oxidization of Zn nanoparticles by the oxygen molecules in the substrate produced during the implantation of F ions. The quality of ZnO QDs increases with the increase of annealing temperature. PMID:21825624

  11. Ferromagnetism in 200-MeV Ag{sup +15}-ion-irradiated Co-implanted ZnO thin films

    SciTech Connect

    Angadi, Basavaraj; Jung, Y.S.; Choi, Won-Kook; Kumar, Ravi; Jeong, K.; Shin, S.W.; Lee, J.H.; Song, J.H.; Wasi Khan, M.; Srivastava, J.P.

    2006-04-03

    Structural, electrical resistivity, and magnetization properties of 200-MeV Ag{sup +15}-ion-irradiated Co-implanted ZnO thin films are presented. The structural studies show the presence of Co clusters whose size is found to increase with increase of Co implantation. The implanted films were irradiated with 200-MeV Ag{sup +15} ions to fluence of 1x10{sup 12} ions/cm{sup 2}. The Co clusters on irradiation dissolve in the ZnO matrix. The electrical resistivity of the irradiated samples is lowered to half. The magnetization hysteresis measurements show ferromagnetic behavior at 300 K, and the coercive field increases with the Co implantation. The ferromagnetism at room temperature is confirmed by magnetic force microscopy measurements. The results are explained on the basis of the close interplay between the electrical and the magnetic properties.

  12. Up conversion from visible to ultraviolet in bulk ZnO implanted with Tm ions

    SciTech Connect

    Monteiro, T.; Neves, A. J.; Soares, M. J.; Carmo, M.C.; Peres, M.; Alves, E.; Rita, E.

    2005-11-07

    We report on the up-converted ultraviolet near-band edge emission of bulk ZnO generated by visible and ultraviolet photons with energies below the band gap. This up-converted photoluminescence was observed in samples intentionally doped with Tm ions, suggesting that the energy levels introduced by the rare earth ion in the ZnO band gap are responsible for this process.

  13. Characteristics of ZnO Wafers Implanted with 60 keV Sn{sup +} Ions at Room Temperature and at 110 K

    SciTech Connect

    Dang, Giang T.; Taniwaki, Masafumi; Kawaharamura, Toshiyuki; Hirao, Takashi; Nitta, Noriko

    2011-01-07

    ZnO wafers implanted with 60 keV Sn{sup +} ions at room temperature (RT) and at 110 K are investigated by means of X-ray diffraction (XRD) and photoluminescence (PL) techniques. The effect of implantation temperature is evident in the XRD and PL data. A yellow-orange (YO) band near 600 nm appears in the PL spectra of the ZnO wafers implanted to the doses of 4x10{sup 14} and 8x10{sup 14} ions/cm{sup 2} at RT. The intensity of this band increases and the peak position blue-shifts after illumination of the samples with the 325 nm line of a He-Cd laser. The PL data suggests that the CB (conduction band){yields}V{sub O}{sup +} and Zn{sub i}{sup +{yields}}V{sub Zn}{sup -} transitions contribute to the photoemission of the YO band.

  14. Hydrogen interstitial in H-ion implanted ZnO bulk single crystals: Evaluation by elastic recoil detection analysis and electron paramagnetic resonance

    NASA Astrophysics Data System (ADS)

    Kaida, T.; Kamioka, K.; Nishimura, T.; Kuriyama, K.; Kushida, K.; Kinomura, A.

    2015-12-01

    The origins of low resistivity in H ion-implanted ZnO bulk single crystals are evaluated by elastic recoil detection analysis (ERDA), electron paramagnetic resonance (EPR), and Van der Pauw methods. The H-ion implantation (peak concentration: 5.0 × 1015 cm-2) into ZnO is performed using a 500 keV implanter. The maximum of the concentration of the implanted H estimated by a TRIM simulation is at 3600 nm in depth. The resistivity decreases from ∼103 Ω cm for un implanted ZnO to 6.5 Ω cm for as-implanted, 2.3 × 10-1 Ω cm for 200 °C annealed, and 3.2 × 10-1 Ω cm for 400 °C annealed samples. The ERDA measurements can evaluate the concentration of hydrogens which move to the vicinity of the surface (surface to 300 nm or 100 nm) because of the diffusion by the annealing at 200 °C and 400 °C. The hydrogen concentration near the surface estimated using the 2.0 MeV helium beam is ∼3.8 × 1013 cm-2 for annealed samples. From EPR measurements, the oxygen vacancy of +charge state (Vo+) is observed in as-implanted samples. The Vo+ related signal (g = 1.96) observed under no illumination disappears after successive illumination with a red LED and appears again with a blue light illumination. The activation energy of as-implanted, 200 °C annealed, and 400 °C annealed samples estimated from the temperature dependence of carrier concentration lies between 29 meV and 23 meV, suggesting the existence of H interstitial as a shallow donor level.

  15. Revealing the surface origin of green band emission from ZnO nanostructures by plasma immersion ion implantation induced quenching

    SciTech Connect

    Yang, Y.; Sun, X. W.; Tay, B. K.; Cao, Peter H. T.; Wang, J. X.; Zhang, X. H.

    2008-03-15

    Surface defect passivation for ZnO nanocombs (NCBs), random nanowires (RNWs), and aligned nanowires (ANWs) was performed through a metal plasma immersion ion implantation with low bias voltages ranging from 0 to 10 kV, where Ni was used as the modification ion. The depth of surface-originated green band (GB) emission is thus probed, revealing the surface origin of the GB. It is also found that the GB is closely related to oxygen gas content during growth of the nanostructures. The GB origin of NCBs and RNWs grown with higher oxygen content is shallower ({approx}0.5 nm), which can be completely quenched with no bias applied. However, the GB origin of ANWs grown at lower oxygen content is much deeper ({approx}7 nm) with a complete quenching bias of 10 kV. Quenching of the GB can be attributed to passivation of the surface hole or electron trapping sites (oxygen vacancies) by Ni ions.

  16. Temperature dependent formation of ZnO and Zn2SiO4 nanoparticles by ion implantation and thermal annealing

    NASA Astrophysics Data System (ADS)

    Pandey, B.; Weathers, D. L.

    2014-08-01

    ZnO and Zn2SiO4 nanoparticles have been synthesized by dual beam implantation of 45 keV ZnO- molecular ions and 15 keV O- ions into Si (100) substrates at room temperature to fluences of 1 × 1017 and 2 × 1017 ions/cm2, respectively. Implanted samples were annealed at different temperatures in a mixture of Ar and H2 for 1 h. Rutherford backscattering spectrometry (RBS) was used to confirm the implanted ion fluences. The diffusion of Zn and O ions due to annealing was studied by using X-ray photoelectron spectroscopy (XPS). It was observed that at 700 °C annealing temperature, oxygen diffused into the substrate whereas Zn diffused in both directions; at 900 °C, oxygen diffused more into the substrate but the Zn diffused outward toward the surface. X-ray diffraction (XRD) was used to investigate the phase formation and particle sizes. At 700 °C annealing temperature, ZnO phase with an average nanoparticle size of ∼17.5 nm was observed whereas at 900 °C annealing temperature, Zn2SiO4 phase with an average nanoparticle size of ∼19 nm was observed.

  17. Characterization of the lattice defects in Ge-ion implanted ZnO bulk single crystals by Rutherford Backscattering: Origins of low resistivity

    NASA Astrophysics Data System (ADS)

    Kamioka, K.; Oga, T.; Izawa, Y.; Kuriyama, K.; Kushida, K.

    2013-07-01

    A Ge ion implantation using a multiple-step energy into ZnO bulk single crystals is performed (net concentration: 2.6 × 1020 cm-3). The origins of low resistivity of the Ge implanted ZnO samples are studied by Rutherford backscattering spectroscopy (RBS), photoluminescence (PL). The resistivity measured by Van der Pauw method decreases from ˜103 Ωcm for the un-implanted samples to 1.45 × 10-2 Ωcm for the as-implanted samples, originating from the lattice displacement of Zn (Zni) (˜30 meV [Look et al., Phys. Rev. Lett. 82, 2552 (1999)]), the existence of which is revealed by the RBS measurements. In contrast, the 1000 °C annealed samples show the higher resistivity of 6.26 × 10-1 Ωcm, indicating that the Zni related defects decrease but still remain despite the annealing. A new PL emission appears at around 372 nm (3.33 eV) in the annealed samples, suggesting a Ge donor with an activation energy of 100 meV. This value corresponds to the activation energy (102 meV) of a Ge donor estimated from the temperature dependence of carrier concentration. These results suggest that the resistivity in the 1000 °C annealed samples results from both the Zni related defects and the electrically activated Ge donor.

  18. Microstrip structures of ZnO nanoparticle aggregates of millimetric length formed by selected-area ion implantation and thermal oxidation.

    PubMed

    Amekura, H; Wang, H-S; Hishita, S; Pan, J; Kishimoto, N; Buchal, Ch; Mantl, S

    2009-02-11

    Regularly arrayed microstrip regions of width approximately 1.4 microm and length extending up to approximately 5 mm, consisting of ZnO nanoparticles (NPs) of diameter approximately 50 nm, were fabricated on silica substrates by a two-step process: i.e., selected-area ion implantation and thermal oxidation. The implantation of 60 keV Zn ions in periodic microstrip regions via a resist mask generated periodic grooves with large wings on the surface of silica glass, which can be ascribed to the radiation-induced plastic deformation of silica and sputtering loss. This is the lowest record of the electronic energy loss (S(e)) value to induce the radiation-induced plastic deformation of silica, while no or very low threshold energy has been predicted from a recent study. After thermal oxidation at 700 degrees C for 1 h, the groove structures with the wings disappeared, and periodic microstrips of ZnO nanoparticle aggregates up to 5 mm long appeared on the surface of the substrate. A clear free-exciton peak due to ZnO NPs is observed from these microstrip structures both in optical absorption and photoluminescence spectra. PMID:19417379

  19. Study of non-linear Hall effect in nitrogen-grown ZnO microstructure and the effect of H{sup +}-implantation

    SciTech Connect

    Kumar, Yogesh Bern, Francis; Barzola-Quiquia, Jose; Lorite, Israel; Esquinazi, Pablo

    2015-07-13

    We report magnetotransport studies on microstructured ZnO film grown by pulsed laser deposition in N{sub 2} atmosphere on a-plane Al{sub 2}O{sub 3} substrates and the effect of low energy H{sup +}-implantation. Non-linearity has been found in the magnetic field dependent Hall resistance, which decreases with temperature. We explain this effect with a two-band model assuming the conduction through two different parallel channels having different types of charge carriers. Reduced non-linearity after H{sup +}-implantation in the grown film is due to the shallow-donor effect of hydrogen giving rise to an increment in the electron density, reducing the effect of the other channel.

  20. Development of novel implants with self-antibacterial performance through in-situ growth of 1D ZnO nanowire.

    PubMed

    Wang, Wenhao; Li, Tak Lung; Wong, Hoi Man; Chu, Paul K; Kao, Richard Y T; Wu, Shuilin; Leung, Frankie K L; Wong, Tak Man; To, Michael K T; Cheung, Kenneth M C; Yeung, Kelvin W K

    2016-05-01

    To prevent the attachment of bacteria to implant surfaces, the 1D zinc oxide nanowire-coating has been successfully developed on material surfaces by using a custom-made hydrothermal approach. The chemical nature, surface topography and wettability of spike-like 1D ZnO nanowire-coating are comprehensively investigated. The anti-adhesive and antimicrobial properties of 1D nanowire-coating are tested against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli by using in vitro live/dead staining and scanning electron microscopy. We find that the adhesion of bacteria can be reduced via the special spike-like topography and that the release of Zn(2+) ions can help suppress the growth of attached bacteria. Furthermore, the antimicrobial effect is also evaluated under in vivo conditions by using a rat model infected with bioluminescent S. aureus. The amount of live bacteria in the rat implanted with a nanowire-coated sample is less than that of the control at various time points. Hence, it is believed that the nanowire-coated material is promising for application in orthopaedic implantation after the long-term animal studies have been completed. PMID:26918511

  1. Characteristic local association of In impurities dispersed in ZnO

    NASA Astrophysics Data System (ADS)

    Sato, W.; Komatsuda, S.; Ohkubo, Y.

    2012-12-01

    Local environments in 0.5 at.% In-doped ZnO were investigated by means of the time-differential perturbed angular correlation (TDPAC) method. In a comparative study, using the 111Cd probe nuclei as the decay products of different parents, 111In and 111mCd, we found that 111In microscopically forms a unique structure with nonradioactive In ion(s) dispersed in ZnO, whereas 111mCd has no specific interaction with the In impurities. The spectral damping of the TDPAC spectra is attributed to the aftereffect following the EC decay of 111In. It was demonstrated from the aftereffect that the local density and/or mobility of conduction electrons at the 111In probe site in the In-doped ZnO is lowered due to the characteristic structure locally formed by the dispersed In ion(s).

  2. PAC studies on impurities in ZnO

    NASA Astrophysics Data System (ADS)

    Deubler, S.; Meier, J.; Schütz, R.; Witthuhn, W.

    1992-01-01

    Acceptor-donor pairs in ZnO are studied by the perturbed angular correlation spectroscopy (PAC) using radioactive 111In/ 111Cd probe atoms. In undoped ZnO the trapping of O-vacancies as well as the trapping of Zn-interstitials at the probe atoms which are located at substitutional Zn sites is observed after different sample treatments. In Cu-, Li-, and Na-doped ZnO the acceptor impurities form complexes with the In donors. The structure of these complexes is given and compared with theoretical calculations.

  3. Growth of a Novel Nanostructured ZnO Urchin: Control of Cytotoxicity and Dissolution of the ZnO Urchin.

    PubMed

    Imani, Roghayeh; Drašler, Barbara; Kononenko, Veno; Romih, Tea; Eleršič, Kristina; Jelenc, Janez; Junkar, Ita; Remškar, Maja; Drobne, Damjana; Kralj-Iglič, Veronika; Iglič, Aleš

    2015-12-01

    The applications of zinc oxide (ZnO) nanowires (NWs) in implantable wireless devices, such as diagnostic nanobiosensors and nanobiogenerators, have recently attracted enormous attention due to their unique properties. However, for these implantable nanodevices, the biocompatibility and the ability to control the behaviour of cells in contact with ZnO NWs are demanded for the success of these implantable devices, but to date, only a few contrasting results from their biocompatibility can be found. There is a need for more research about the biocompatibility of ZnO nanostructures and the adhesion and viability of cells on the surface of ZnO nanostructures. Here, we introduce synthesis of a new nature-inspired nanostructured ZnO urchin, with the dimensions of the ZnO urchin's acicula being controllable. To examine the biocompatibility and behaviour of cells in contact with the ZnO urchin, the Madin-Darby canine kidney (MDCK) epithelial cell line was chosen as an in vitro experimental model. The results of the viability assay indicated that, compared to control, the number of viable cells attached to the surface of the ZnO urchin and its surrounding area were reduced. The measurements of the Zn contents of cell media confirmed ZnO dissolution, which suggests that the ZnO dissolution in cell culture medium could lead to cytotoxicity. A purposeful reduction of ZnO cytotoxicity was achieved by surface coating of the ZnO urchin with poly(vinylidene fluorid-co-hexafluoropropylene) (PVDF-HFP), which changed the material matrix to slow the Zn ion release and consequently reduce the cytotoxicity of the ZnO urchin without reducing its functionality. PMID:26573932

  4. Growth of a Novel Nanostructured ZnO Urchin: Control of Cytotoxicity and Dissolution of the ZnO Urchin

    NASA Astrophysics Data System (ADS)

    Imani, Roghayeh; Drašler, Barbara; Kononenko, Veno; Romih, Tea; Eleršič, Kristina; Jelenc, Janez; Junkar, Ita; Remškar, Maja; Drobne, Damjana; Kralj-Iglič, Veronika; Iglič, Aleš

    2015-11-01

    The applications of zinc oxide (ZnO) nanowires (NWs) in implantable wireless devices, such as diagnostic nanobiosensors and nanobiogenerators, have recently attracted enormous attention due to their unique properties. However, for these implantable nanodevices, the biocompatibility and the ability to control the behaviour of cells in contact with ZnO NWs are demanded for the success of these implantable devices, but to date, only a few contrasting results from their biocompatibility can be found. There is a need for more research about the biocompatibility of ZnO nanostructures and the adhesion and viability of cells on the surface of ZnO nanostructures. Here, we introduce synthesis of a new nature-inspired nanostructured ZnO urchin, with the dimensions of the ZnO urchin's acicula being controllable. To examine the biocompatibility and behaviour of cells in contact with the ZnO urchin, the Madin-Darby canine kidney (MDCK) epithelial cell line was chosen as an in vitro experimental model. The results of the viability assay indicated that, compared to control, the number of viable cells attached to the surface of the ZnO urchin and its surrounding area were reduced. The measurements of the Zn contents of cell media confirmed ZnO dissolution, which suggests that the ZnO dissolution in cell culture medium could lead to cytotoxicity. A purposeful reduction of ZnO cytotoxicity was achieved by surface coating of the ZnO urchin with poly(vinylidene fluorid-co-hexafluoropropylene) (PVDF-HFP), which changed the material matrix to slow the Zn ion release and consequently reduce the cytotoxicity of the ZnO urchin without reducing its functionality.

  5. Iliac artery mural thrombus formation. Effect of antiplatelet therapy on 111In-platelet deposition in baboons

    SciTech Connect

    Hanson, S.R.; Paxton, L.D.; Harker, L.A.

    1986-09-01

    To measure the rate, extent, and time course of arterial mural thrombus formation in vivo and to assess the effects of antiplatelet therapy in that setting, we have studied autologous /sup 111/In-platelet deposition induced by experimental iliac artery aneurysms in baboons. Scintillation camera imaging analyses were performed at 1, 24, 48, and 72 hours after implantation of the device. Correction for tissue attenuation was determined by using a small, comparably located /sup 111/In source implanted at the time of surgery. In five animals, /sup 111/In-platelet activity accumulated progressively after device implantation, reaching a maximum after the third day. Repeat image analysis carried out 2 weeks after the surgical procedure also showed progressive accumulation of /sup 111/In-platelets over 3 days but at markedly reduced amounts as compared with the initial study. In five additional animals, treatment with a combination of aspirin and dipyridamole begun 1 hour after surgical implantation reduced /sup 111/In-platelet deposition to negligible levels by the third day. Although platelet survival time was shortened and platelet turnover was reciprocally increased in all operated animals, platelet survival and turnover were not affected by antiplatelet therapy. We conclude that, in contrast to platelet survival and turnover measurements, /sup 111/In-platelet imaging is a reliable and sensitive method for localizing and quantifying focal arterial thrombi and for assessing the effects of antiplatelet therapy.

  6. Effect of laser annealing using high repetition rate pulsed laser on optical properties of phosphorus-ion-implanted ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Shimogaki, Tetsuya; Ofuji, Taihei; Tetsuyama, Norihiro; Okazaki, Kota; Higashihata, Mitsuhiro; Nakamura, Daisuke; Ikenoue, Hiroshi; Asano, Tanemasa; Okada, Tatsuo

    2014-02-01

    The effect of high repetition rate pulsed laser annealing with a KrF excimer laser on the optical properties of phosphorus-ion-implanted zinc oxide nanorods has been investigated. The recovery levels of phosphorus-ion-implanted zinc oxide nanorods have been measured by photoluminescence spectra and cathode luminescence images. Cathode luminescence disappeared over 300 nm below the surface due to the damage caused by ion implantation with an acceleration voltage of 25 kV. When the annealing was performed at a low repetition rate of the KrF excimer laser, cathode luminescence was recovered only in a shallow area below the surface. The depth of the annealed area was increased along with the repetition rate of the annealing laser. By optimizing the annealing conditions such as the repetition rate, the irradiation fluence and so on, we have succeeded in annealing the whole damaged area of over 300 nm in depth and in observing cathode luminescence. Thus, the effectiveness of high repetition rate pulsed laser annealing on phosphorus-ion-implanted zinc oxide nanorods was demonstrated.

  7. ZnO quantum dots-decorated ZnO nanowires for the enhancement of antibacterial and photocatalytic performances

    NASA Astrophysics Data System (ADS)

    Wu, Jyh Ming; Tsay, Li-Yi

    2015-10-01

    We demonstrate highly antibacterial activities for killing off Staphylococcus aureus and Escherichia coli using ZnO nanowires decorated with ZnO quantum dots (so-called ZnO QDs/NWs) under visible-light irradiation and dark conditions. The average size of the ZnO QDs is in the range of 3-5 nm; these were uniformly dispersed on the ZnO nanowires’ surface to form the ZnO QDs/NWs. A significant blue-shift effect was observed using photoluminescence (PL) spectra. The size of the ZnO QDs is strongly dependent on the material’s synthesis time. The ZnO QDs/NWs exhibited an excellent photocatalytic activity under visible-light irradiation. The ZnO QDs’ active sites (i.e. the O-H bond and Zn2+) accelerate the photogenerated-carrier migration from the QDs to the NWs. As a consequence, the electrons reacted with the dissolved oxygen to form oxygen ions and produced hydroperoxyl radicals to enhance photocatalytic activity. The antibacterial activities (as indicated by R-factor-inhibiting activity) of the ZnO QDs/NWs for killing off Staphylococcus aureus and Escherichia coli is around 4.9 and 5.5 under visible-light irradiation and dark conditions, respectively. The hydroxyl radicals served as an efficient oxidized agent for decomposing the organic dye and microorganism species. The antibacterial activities of the ZnO QDs/NWs in the dark may be attributed to the Zn2+ ions that were released from the ZnO QDs and infused into the microbial solution against the growth of bacteria thus disrupting the microorganism. The highly antibacterial and photocatalytic activity of the ZnO QDs/NWs can be well implanted on a screen window, thus offering a promising solution to inhibit the spread of germs under visible-light and dark conditions.

  8. Green emission in carbon doped ZnO films

    SciTech Connect

    Tseng, L. T.; Yi, J. B. Zhang, X. Y.; Xing, G. Z.; Luo, X.; Li, S.; Fan, H. M.; Herng, T. S.; Ding, J.; Ionescu, M.

    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.

  9. Green emission in carbon doped ZnO films

    NASA Astrophysics Data System (ADS)

    Tseng, L. T.; Yi, J. B.; Zhang, X. Y.; Xing, G. Z.; Fan, H. M.; Herng, T. S.; Luo, X.; Ionescu, M.; Ding, J.; Li, S.

    2014-06-01

    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.

  10. Ferromagnetism in Co- and Mn-doped ZnO

    NASA Astrophysics Data System (ADS)

    Theodoropoulou, N. A.; Hebard, A. F.; Norton, D. P.; Budai, J. D.; Boatner, L. A.; Lee, J. S.; Khim, Z. G.; Park, Y. D.; Overberg, M. E.; Pearton, S. J.; Wilson, R. G.

    2003-12-01

    Bulk single crystals of Sn-doped ZnO were implanted with Co or Mn at doses designed to produce transition metal concentrations of 3-5 at.% in the near-surface (˜2000 Å) region. The implantation was performed at ˜350 °C to promote dynamic annealing of ion-induced damage. Following annealing at 700 °C, temperature-dependent magnetization measurements showed ordering temperatures of ˜300 K for Co- and ˜250 K for Mn-implanted ZnO. Clear hysteresis loops were obtained at these temperatures. The coercive fields were ⩽100 Oe for all measurement temperatures. X-ray diffraction showed no detectable second phases in the Mn-implanted material. One plausible origin for the ferromagnetism in this case is a carrier-induced mechanism. By sharp contrast, the Co-implanted material showed evidence for the presence of Co precipitates with hexagonal symmetry, which is the cause of the room temperature ferromagnetism. Our results are consistent with the stabilization of ferromagnetic states by electron doping in transition metal-doped ZnO predicted by Sato and Katayama-Yoshida [Jpn. J. Appl. Phys. 40 (2001) L334]. This work shows the excellent promise of Mn-doped ZnO for potential room temperature spintronic applications.

  11. Immunoscintigraphy with 111In antimyosin Fab.

    PubMed

    Morguet, A J; Munz, D L; Kreuzer, H; Emrich, D

    1990-11-01

    Monoclonal 111In antimyosin Fab is a marker for myocytes which have lost their membrane integrity. Because of the slow blood pool clearance of the radiopharmaceutical, imaging is usually started 24-48 h after intravenous injection of 74 MBq of the tracer. This long postinjection interval restricts its utilization in the primary diagnosis of acute myocardial infarction. However, antimyosin may help to differentiate between necrotic and viable myocardium in the subacute stage of incomplete myocardial infarction. Serial endomyocardial biopsy for early detection of transplant rejection after heart transplantation may be partially replaced or supplemented by antimyosin scintigraphy. The compound may facilitate the diagnosis of myocarditis. Other potential indications may be prognostic assessment of dilated cardiomyopathy, monitoring cardiotoxic side-effects of chemotherapeutics, recognition of cardiac contusion as well as diagnosis of rhabdo- and leiomyosarcoma. In specific clinical situations 111In antimyosin Fab immunoscintigraphy may provide valuable diagnostic information. PMID:2277688

  12. Control of optical and electrical properties of ZnO nanocrystals by nanosecond-laser annealing

    NASA Astrophysics Data System (ADS)

    Shimogaki, T.; Ofuji, T.; Tetsuyama, N.; Kawahara, H.; Higashihata, M.; Ikenoue, H.; Nakamura, D.; Okada, T.

    2014-03-01

    Effects of laser annealing on electrical and optical properties of Zinc oxide (ZnO) nanocrystals, which are expected as building blocks for optoelectronic devices, have been investigated in this study. In the case of fabricating p-n junction in single one-dimensional ZnO nanocrystal, phosphorus-ions implanted p-type ZnO nanocrystals were recrystallized and recovered in the optical properties by nanosecond-laser annealing using a KrF excimer laser. Antimony-doped p-type ZnO nanocrystals were synthesized by irradiating laminated structure which antimony thin film were deposited on ZnO nanocrystals with the laser beam. Additionally, it is possible to control the growth rate of ZnO nanowires by using laser annealing. Irradiating with pulsed laser a part of ZnO buffer layer deposited on the a-cut sapphire substrate, then ZnO nanowires were grown on the ZnO buffer layer by the nanoparticle assisted pulsed laser deposition method. As a result, the clear boundary of the laser annealed and non-laser annealed area was appeared. It was observed that ZnO nanowires were grown densely at non-laser annealed area, on the other hand, sparse ones were grown at the laser-annealed region. In this report, the possibility of laser annealing techniques to establish the stable and reliable fabrication process of ZnO nanowires-based LD and LED are discussed on the basis of experimental results.

  13. Killing of human lung cancer cells using a new ( sup 111 In)bleomycin complex ( sup 111 In)BLMC

    SciTech Connect

    Hou, D.Y.; Hamburger, A.W.; Beach, J.L.; Maruyama, Y. )

    1989-01-01

    The ability of a ({sup 111}In)bleomycin complex (({sup 111}In)BLMC) to kill five cell lines of human lung cancer (small cell lung cancer) was investigated. Cells were exposed to either 0.9% NaCl, ({sup 111}In)Cl3, BLM, ({sup 111}In)BLMC, nonradioactive InCl3, or In-BLMC for 60 minutes, plated in soft agarose, and assessed for colony formation. ({sup 111}In)BLMC (40-200 microCi carried by 15-25 micrograms BLM/ml) was more cytotoxic than BLM (15-25 micrograms BLM/ml) by a factor of 1.6-5.3 for five cell lines. The percent survival of N417 cells was 28.4 for ({sup 111}In)BLMC (40 microCi/15 micrograms BLM/ml) and 54.3 for BLM (15 micrograms/ml); 1.9 for ({sup 111}In)BLMC (200 microCi/25 micrograms BLM/ml), and 10.0 for BLM (25 micrograms/ml). {sup 111}InCl3 (200 microCi/ml) and nonradioactive InCl3 failed to inhibit colony formation. The new ({sup 111}In)BLMC may be useful for therapy of some lung cancer patients.

  14. Characterization of ZnO and Zn0.95Co0.05O prepared by sol-gel method using PAC spectroscopy

    NASA Astrophysics Data System (ADS)

    Mercurio, M. E.; Carbonari, A. W.; Cordeiro, M. R.; Saxena, R. N.

    The measurement of the electric field gradient (efg) with PAC spectroscopy was used to follow the heat treatment during the preparation of ZnO samples using sol-gel method. In particular, the investigation was carried out on samples of intrinsically n-type II-VI wurtzite semiconductor ZnO and Co-doped Zn0.95Co0.05O samples prepared by sol-gel methodology from pure metallic Zn(99.9999%). Carrier-free 111In nuclei were introduced in the samples by thermal diffusion. 111In solution was added to the precursor sol-gel solution prior to the formation of gel material. PAC measurements were carried out to follow the formation of the ZnO. Two undoped ZnO samples, which were heated in air and argon atmosphere, show different results. PAC measurements were also used to follow the 111In diffusion in a commercially purchased ZnO (99.99%) sample as well as to compare the results with the measurements taken with sol-gel prepared samples. The results show that samples prepared by sol-gel process followed by heating in argon produce better quality ZnO samples. The results also show that the Co atoms in Zn0.95Co0.05O are in substitutional sites.

  15. Characterization of ZnO and Zn0.95Co0.05O prepared by sol-gel method using PAC spectroscopy

    NASA Astrophysics Data System (ADS)

    Mercurio, M. E.; Carbonari, A. W.; Cordeiro, M. R.; Saxena, R. N.

    2007-07-01

    The measurement of the electric field gradient (efg) with PAC spectroscopy was used to follow the heat treatment during the preparation of ZnO samples using sol-gel method. In particular, the investigation was carried out on samples of intrinsically n-type II-VI wurtzite semiconductor ZnO and Co-doped Zn0.95Co0.05O samples prepared by sol-gel methodology from pure metallic Zn(99.9999%). Carrier-free 111In nuclei were introduced in the samples by thermal diffusion. 111In solution was added to the precursor sol-gel solution prior to the formation of gel material. PAC measurements were carried out to follow the formation of the ZnO. Two undoped ZnO samples, which were heated in air and argon atmosphere, show different results. PAC measurements were also used to follow the 111In diffusion in a commercially purchased ZnO (99.99%) sample as well as to compare the results with the measurements taken with sol-gel prepared samples. The results show that samples prepared by sol-gel process followed by heating in argon produce better quality ZnO samples. The results also show that the Co atoms in Zn0.95Co0.05O are in substitutional sites.

  16. Theoretical and experimental investigation of possible ferromagnetic ordering in wide band gap ZnO and related systems

    NASA Astrophysics Data System (ADS)

    Sarkar, A.; Sanyal, D.; Dechoudhury, S.; Bhowmick, D.; Rakshit, T.; Chakrabarti, A.

    2016-07-01

    Room temperature ferromagnetic ordering has been induced in the ZnO thin film by 26 keV C ion implantation. Several orders of resistivity reduction have been observed after C implantation. Ab initio calculations in the frame work of density functional theory indicates that C substitution at the oxygen vacancy site can induce magnetic moment in ZnO. C substitution at zinc vacancy site cannot produce any ferromagnetic moment although zinc vacancy in undoped ZnO induces the same. It has also been shown that ferromagnetic ZnO with sufficient hole concentration at room temperature cannot be realized by adjusting native vacancies only. After C substitution in the system, donor like states appear near the conduction band causing more n-type character compared to undoped ZnO.

  17. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  18. The identification and nature of bound exciton I-line PL systems in ZnO

    SciTech Connect

    Johnston, K.; Cullen, J.; Henry, M. O.; McGlynn, Enda; Khawaga, Rehab I.

    2013-12-04

    The chemical identification of donor bound excitons in ZnO has been studied using radioactive ions. Implantations of {sup 117}Ag - which decays to radioactive Cd and In - have enabled the identification of the I{sub 2} optical feature as being the ionized donor counterpart of I{sub 9}, one of the most prominent optical features in the photoluminescence spectrum of ZnO. Both of these lines are consistent with In occupying a Zn site.

  19. The identification and nature of bound exciton I-line PL systems in ZnO

    NASA Astrophysics Data System (ADS)

    Johnston, K.; Cullen, J.; Henry, M. O.; McGlynn, Enda; Khawaga, Rehab I.

    2013-12-01

    The chemical identification of donor bound excitons in ZnO has been studied using radioactive ions. Implantations of 117Ag - which decays to radioactive Cd and In - have enabled the identification of the I2 optical feature as being the ionized donor counterpart of I9, one of the most prominent optical features in the photoluminescence spectrum of ZnO. Both of these lines are consistent with In occupying a Zn site.

  20. Hydrogen-Induced Plastic Deformation in ZnO

    NASA Astrophysics Data System (ADS)

    Lukáč, F.; Čížek, J.; Vlček, M.; Procházka, I.; Anwand, W.; Brauer, G.; Traeger, F.; Rogalla, D.; Becker, H.-W.

    In the present work hydrothermally grown ZnO single crystals covered with Pd over-layer were electrochemically loaded with hydrogen and the influence of hydrogen on ZnO micro structure was investigated by positron annihilation spectroscopy (PAS). Nuclear reaction analysis (NRA) was employed for determination of depth profile of hydrogen concentration in the sample. NRA measurements confirmed that a substantial amount of hydrogen was introduced into ZnO by electrochemical charging. The bulk hydrogen concentration in ZnO determined by NRA agrees well with the concentration estimated from the transported charge using the Faraday's law. Moreover, a subsurface region with enhanced hydrogen concentration was found in the loaded crystals. Slow positron implantation spectroscopy (SPIS) investigations of hydrogen-loaded crystal revealed enhanced concentration of defects in the subsurface region. This testifies hydrogen-induced plastic deformation of the loaded crystal. Absorbed hydrogen causes a significant lattice expansion. At low hydrogen concentrations this expansion is accommodated by elastic straining, but at higher concentrations hydrogen-induced stress exceeds the yield stress in ZnO and plastic deformation of the loaded crystal takes place. Enhanced hydrogen concentration detected in the subsurface region by NRA is, therefore, due to excess hydrogen trapped at open volume defects introduced by plastic deformation. Moreover, it was found that hydrogen-induced plastic deformation in the subsurface layer leads to typical surface modification: formation of hexagonal shape pyramids on the surface due to hydrogen-induced slip in the [0001] direction.

  1. Osteomyelitis complicating fracture: pitfalls of /sup 111/In leukocyte scintigraphy

    SciTech Connect

    Kim, E.E.; Pjura, G.A.; Lowry, P.A.; Gobuty, A.H.; Traina, J.F.

    1987-05-01

    /sup 111/In-labeled leukocyte imaging has shown greater accuracy and specificity than alternative noninvasive methods in the detection of uncomplicated osteomyelitis. Forty patients with suspected osteomyelitis complicating fractures (with and without surgical intervention) were evaluated with /sup 111/In-labeled leukocytes. All five patients with intense focal uptake, but only one of 13 with no uptake, had active osteomyelitis. However, mild to moderate /sup 111/In leukocyte uptake, observed in 22 cases, indicated the presence of osteomyelitis in only four of these; the other false-positive results were observed in noninfected callus formation, heterotopic bone formation, myositis ossificans, and sickle-cell disease. These results suggest that /sup 111/In-labeled leukocyte imaging is useful for the evaluation of suspected osteomyelitis complicating fracture but must be used in conjunction with clinical and radiographic correlation to avoid false-positive results.

  2. Development of 111In-labeled porphyrins for SPECT imaging

    PubMed Central

    Sadeghi, Shaghayegh; Mirzaei, Mohammad; Rahimi, Mohammad; Jalilian, Amir R.

    2014-01-01

    Objective(s): The aim of this research was the development of 111In-labeled porphyrins as possible radiopharmaceuticals for the imaging of tumors. Methods: Ligands, 5, 10, 15, 20-tetrakis (3, 5-dihydroxyphenyl) porphyrin) (TDHPP), 5, 10, 15, 20-tetrakis (4-hydroxyphenyl) porphyrin (THPP) and 5, 10, 15, 20-tetrakis (3,4-dimethoxyphenyl) porphyrin) (TDMPP) were labeled with 111InCl3 (produced from proton bombardment of natCd target) in 60 min at 80 ºC. Quality control of labeled compounds was performed via RTLC and HPLC followed by stability studies in final formulation and presence of human serum at 37 ºC for 48 h as well as partition coefficient determination. The biodistribution studies performed using tissue dissection and SPECT imaging up to 24h. Results: The complexes were prepared with more than 99% radiochemical purity (HPLC and RTLC) and high stability to 48 h. Partition coefficients (calculated as log P) for 111In-TDHPP, 111In-THPP and 111In-TDMPP were 0.88, 0.8 and 1.63 respectively. Conclusion: Due to urinary excretion with fast clearance for 111In-TDMPP, this complex is probably a suitable candidate for considering as a possible tumor imaging agent. PMID:27408865

  3. Cochlear Implants

    MedlinePlus

    ... electrodes are inserted. The electronic device at the base of the electrode array is then placed under ... FDA approval for implants The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults ...

  4. Goserelin Implant

    MedlinePlus

    Goserelin implant is used in combination with radiation therapy and other medications to treat localized prostate cancer and is ... treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications called gonadotropin- ...

  5. Cochlear Implants

    MedlinePlus

    A cochlear implant is a small, complex electronic device that can help to provide a sense of sound. People who are ... of-hearing can get help from them. The implant consists of two parts. One part sits on ...

  6. Carmustine Implant

    MedlinePlus

    Carmustine implant is used along with surgery and sometimes radiation therapy to treat malignant glioma (a certain type of ... Carmustine implant comes as a small wafer that is placed in the brain by a doctor during surgery to ...

  7. Breast Implants

    MedlinePlus

    ... Updated Safety Information (Consumer Article) FDA Provides Updated Safety Data on Silicone Gel-Filled Breast Implants (Press Announcement) [ARCHIVED] Breast Implant Guidance for Industry (2006) Post Approval Studies Webpage Freedom of Information ...

  8. Cochlear implant

    MedlinePlus

    ... antenna. This part of the implant receives the sound, converts the sound into an electrical signal, and sends it to ... implants allow deaf people to receive and process sounds and speech. However, these devices do not restore ...

  9. /sup 111/In-/sup 109/In mass difference

    SciTech Connect

    Takagui, E.M.; Dietzsch, O.

    1980-04-01

    A measurement of the difference of Q values for the /sup 108/Cd(/sup 3/He,d)/sup 109/In and the /sup 110/Cd(/sup 3/He,d)/sup 111/In reactions shows a significant discrepancy with the value from the 1977 Atomic Mass Tables. We find Q(/sup 110/Cd(/sup 3/He,d)/sup 111/In) -Q(/sup 108/Cd(/sup 3/He,d)/sup 109/In)=806.5 +- 2.6 keV, leading to a new improved mass excess difference for /sup 111/In-/sup 109/In of -1904.5 +- 7.5 keV.

  10. Osteogenic activity and antibacterial effect of zinc ion implanted titanium.

    PubMed

    Jin, Guodong; Cao, Huiliang; Qiao, Yuqin; Meng, Fanhao; Zhu, Hongqin; Liu, Xuanyong

    2014-05-01

    Titanium (Ti) and its alloys are widely used as orthopedic and dental implants. In this work, zinc (Zn) was implanted into oxalic acid etched titanium using plasma immersion ion implantation technology. Scanning electron microscopy and X-ray photoelectron spectroscopy were used to investigate the surface morphology and composition of Zn-implanted titanium. The results indicate that the depth profile of zinc in Zn-implanted titanium resembles a Gaussian distribution, and zinc exists in the form of ZnO at the surface whereas in the form of metallic Zn in the interior. The Zn-implanted titanium can significantly stimulate proliferation of osteoblastic MC3T3-E1 cells as well as initial adhesion, spreading activity, ALP activity, collagen secretion and extracellular matrix mineralization of the rat mesenchymal stem cells. The Zn-implanted titanium presents partly antibacterial effect on both Escherichia coli and Staphylococcus aureus. The ability of the Zn-implanted titanium to stimulate cell adhesion, proliferation and differentiation as well as the antibacterial effect on E. coli can be improved by increasing implantation time even to 2 h in this work, indicating that the content of zinc implanted in titanium can easily be controlled within the safe concentration using plasma immersion ion implantation technology. The Zn-implanted titanium with excellent osteogenic activity and partly antibacterial effect can serve as useful candidates for orthopedic and dental implants. PMID:24632388

  11. Monitoring of cardiac antirejection therapy with /sup 111/In lymphocytes

    SciTech Connect

    Lerch, R.A.; Bergmann, S.R.; Carlson, E.M.; Saffitz, J.E.; Sobel, B.E.

    1982-06-01

    To determine whether lymphocytes labeled with /sup 111/In permit noninvasive assessment of antirejection therapy, we performed 40 allogeneic heterotopic cardiac transplants in rats. Antirejection therapy with azathioprine (30 mg/kg) and sodium salicylate (200 mg/kg) prolonged contractile function of the graft from 7.5 +/- 1.5 (s.d.) days in controls to 19.4 +/- 3.7 days in treated animals. Six to seven days after transplantation, autologous lymphocytes labeled with /sup 111/In were injected intravenously in seven untreated and eight treated rats. Scintigraphy and organ counting were performed 24 hr after administration of labeled cells. At sacrifice all grafts in untreated rats exhibited contractile failure, whereas grafts in all treated rats were beating well. Transplants in untreated recipients exhibited marked accumulation of /sup 111/In lymphocytes detectable scintigraphically, with ratios of 7.7 +/- 1.9 for the activity in the transplant over that in the native heart (HT/HO), as obtained by well counting. In contrast, accumulation was not scintigraphically detectable in transplants of treated rats, with HT/HO ratios of 2.6 +/- 1.8 (p less than 0.005). The results suggested that imaging with /sup 111/In-labeled lymphocytes will permit noninvasive assessment of antirejection therapy.

  12. Lattice sites of Na dopants in ZnO

    NASA Astrophysics Data System (ADS)

    Wahl, U.; Correia, J. G.; Amorim, L.; Decoster, S.; da Silva, M. R.; Pereira, L. M. C.

    2016-09-01

    The angular distribution of β ‑ particles emitted by the radioactive isotope 24Na was monitored following implantation into ZnO single crystals at fluences above 5 × 1012 cm‑2 at CERN’s ISOLDE facility. We identified sodium on two distinct sites: on substitutional Zn sites and on interstitial sites that are close to the so-called octahedral site. The interstitial Na was to a large extent already converted to substitutional Na for annealing at 200 °C, from which an activation energy of 0.8–1.3 eV, most likely around 1.2 eV, is estimated for the migration of interstitial Na in ZnO.

  13. Hyperfine fields in ZnO studied under uni- and biaxial pressure

    NASA Astrophysics Data System (ADS)

    Przewodnik, R.; Kessler, P.; Vianden, R.

    2013-05-01

    The II-VI semiconductor ZnO has many potential applications in optoelectronic and sensor devices. When used as a transparent conducting contact it is often grown epitaxially onto a different substrate with the consequence that the layers are biaxially strained due to lattice mismatch. Similarly, impurity-implanted layers can lead to the development of local strain fields. Strain usually changes the electronic properties of layers and/ or implanted crystal regions. Detailed knowledge about local strain and its influence on the crystal fields is therefore helpful in predicting changes in crystal properties. The perturbed angular correlation technique was applied to study the electric field gradient (EFG) at the site of implanted In dopants in ZnO under uniaxial and biaxial strain. The observed linear change of the EFG with pressure and a change in symmetry due to compression perpendicular to the c-axis could be well reproduced by theoretical calculations using the point charge model.

  14. Advances in methods to obtain and characterise room temperature magnetic ZnO

    SciTech Connect

    Lorite, I.; Kumar, P.; Esquinazi, P.; Straube, B.; Villafuerte, M.; Ohldag, H.; Rodríguez Torres, C. E.; Perez de Heluani, S.; Antonov, V. N.; Bekenov, L. V.; Ernst, A.; and others

    2015-02-23

    We report the existence of magnetic order at room temperature in Li-doped ZnO microwires after low energy H{sup +} implantation. The microwires with diameters between 0.3 and 10 μm were prepared by a carbothermal process. We combine spectroscopy techniques to elucidate the influence of the electronic structure and local environment of Zn, O, and Li and their vacancies on the magnetic response. Ferromagnetism at room temperature is obtained only after implanting H{sup +} in Li-doped ZnO. The overall results indicate that low-energy proton implantation is an effective method to produce the necessary amount of stable Zn vacancies near the Li ions to trigger the magnetic order.

  15. Advances in methods to obtain and characterise room temperature magnetic ZnO

    NASA Astrophysics Data System (ADS)

    Lorite, I.; Straube, B.; Ohldag, H.; Kumar, P.; Villafuerte, M.; Esquinazi, P.; Rodríguez Torres, C. E.; Perez de Heluani, S.; Antonov, V. N.; Bekenov, L. V.; Ernst, A.; Hoffmann, M.; Nayak, S. K.; Adeagbo, W. A.; Fischer, G.; Hergert, W.

    2015-02-01

    We report the existence of magnetic order at room temperature in Li-doped ZnO microwires after low energy H+ implantation. The microwires with diameters between 0.3 and 10 μm were prepared by a carbothermal process. We combine spectroscopy techniques to elucidate the influence of the electronic structure and local environment of Zn, O, and Li and their vacancies on the magnetic response. Ferromagnetism at room temperature is obtained only after implanting H+ in Li-doped ZnO. The overall results indicate that low-energy proton implantation is an effective method to produce the necessary amount of stable Zn vacancies near the Li ions to trigger the magnetic order.

  16. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.

  17. High Productivity Implantation ''PARTIAL IMPLANT''

    SciTech Connect

    Hino, Masayoshi; Miyamoto, Naoki; Sakai, Shigeki; Matsumoto, Takao

    2008-11-03

    The patterned ion implantation 'PARTIAL IMPLANT' has been developed as a productivity improvement tool. The Partial Implant can form several different ion dose areas on the wafer surface by controlling the speed of wafer moving and the stepwise rotation of twist axis. The Partial Implant system contains two implant methods. One method is 'DIVIDE PARTIAL IMPLANT', that is aimed at reducing the consumption of the wafer. The Divide Partial Implant evenly divides dose area on one wafer surface into two or three different dose part. Any dose can be selected in each area. So the consumption of the wafer for experimental implantation can be reduced. The second method is 'RING PARTIAL IMPLANT' that is aimed at improving yield by correcting electrical characteristic of devices. The Ring Partial Implant can form concentric ion dose areas. The dose of wafer external area can be selected to be within plus or minus 30% of dose of wafer central area. So the electrical characteristic of devices can be corrected by controlling dose at edge side on the wafer.

  18. [Implant allergies].

    PubMed

    Thomas, P; Thomsen, M

    2010-03-01

    An increasing number of patients receive and benefit from osteosynthesis materials or artificial joint replacement. The most common complications are mechanical problems or infection. Metals like nickel, chromium and cobalt as well as bone cement components like acrylates and gentamicin are potential contact allergens which can cause intolerance reactions to implants. Eczema, delayed wound/bone healing, recurrent effusions, pain and implant loosening all have been described as manifestation of implant allergy. In contrast to the high incidence of cutaneous metal allergy, allergies associated with implants are rare. Diagnosis of metal implant allergy is still difficult. Thus differential diagnoses--in particular infection--have to be excluded and a combined approach of allergologic diagnostics by patch test and histopathology of peri-implant tissue is recommended. It is still unknown which conditions induce allergic sensitization to implants or trigger peri-implant allergic reactions in the case of preexisting cutaneous metal allergy. Despite the risk of developing complications being unclear, titanium based osteosynthesis materials are recommended for metal allergic patients and the use of metal-metal couplings in arthroplasty is not recommended for such patients. If the regular CoCr-polyethylene articulation is employed, the patient should give informed written consent. PMID:20204719

  19. Standardisation and half-life measurements of (111)In.

    PubMed

    Dziel, Tomasz; Listkowska, Anna; Tymiński, Zbigniew

    2016-03-01

    The standardisation of (111)In by 4π(LS)-γ coincidence and anticoincidence counting is presented. Absolute measurements were performed for samples with different concentrations of carrier solution and for different window settings in the gamma channel. The radioactive concentration of the master solution determined on the same reference date was consistent for all measurements performed. The evaluated typical uncertainty was 0.43%. The half-life of (111)In was determined using a time series of measurements performed with an ionisation chamber. A least squares fit of the measured data resulted in a half-life of 2.8067 (34) days consistent with Decay Data Evaluation Project recommended value (0.064% higher than the DDEP value). PMID:26651174

  20. Minority anion substitution by Ni in ZnO

    SciTech Connect

    Pereira, L. M. C.; Amorim, L. M.; Decoster, S.; Temst, K.; Vantomme, A.; Wahl, U.; Correia, J. G.; Silva, D. J.; Bosne, E.; Silva, M. R. da

    2013-08-26

    We report on the lattice location of implanted Ni in ZnO using the β{sup −} emission channeling technique. In addition to the majority substituting for the cation (Zn), a significant fraction of the Ni atoms occupy anion (O) sites. Since Ni is chemically more similar to Zn than it is to O, the observed O substitution is rather puzzling. We discuss these findings with respect to the general understanding of lattice location of dopants in compound semiconductors. In particular, we discuss potential implications on the magnetic behavior of transition metal doped dilute magnetic semiconductors.

  1. Determination of secondary ion mass spectrometry relative sensitivity factors for polar and non-polar ZnO

    SciTech Connect

    Laufer, Andreas; Volbers, Niklas; Eisermann, Sebastian; Meyer, Bruno K.; Potzger, Kay; Geburt, Sebastian; Ronning, Carsten

    2011-11-01

    Zinc oxide (ZnO) is regarded as a promising material for optoelectronic devices, due to its electronic properties. Solely, the difficulty in obtaining p-type ZnO impedes further progress. In this connection, the identification and quantification of impurities is a major demand. For quantitative information using secondary ion mass spectrometry (SIMS), so-called relative sensitivity factors (RSF) are mandatory. Such conversion factors did not yet exist for ZnO. In this work, we present the determined RSF values for ZnO using primary (ion implanted) as well as secondary (bulk doped) standards. These RSFs have been applied to commercially available ZnO substrates of different surface termination (a-plane, Zn-face, and O-face) to quantify the contained impurities. Although these ZnO substrates originate from the same single-crystal, we observe discrepancies in the impurity concentrations. These results cannot be attributed to surface termination dependent RSF values for ZnO.

  2. [Pharmacokinetic substantiation of the use of 111In-citrate in bone marrow studies].

    PubMed

    Korsunskiĭ, V N; Tarasenko, Iu I; Koval'chuk, N D; Kosheleva, I Iu; Popov, V I

    1986-07-01

    Soviet radiopharmaceutical 111In-citrin has been studied to define its possible application for marrow visualization. 111In-citrin has been shown to accumulate in the red marrow, parenchymal organs and to be excreted from animal organism by urinary system predominately. 111In-citrin has advantages in defining the nuclide concentrations in marrow blood and serum as compared with colloid preparations and 111In-chloride. 111In-citrin is supposed to be an adequate radiopharmaceutical preparation for visualization of the red marrow. PMID:3736386

  3. Goserelin Implant

    MedlinePlus

    ... which the type of tissue that lines the uterus [womb] grows in other areas of the body ... with the treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications ...

  4. Ion Implantation

    NASA Astrophysics Data System (ADS)

    Langouche, G.; Yoshida, Y.

    In this tutorial we describe the basic principles of the ion implantation technique and we demonstrate that emission Mössbauer spectroscopy is an extremely powerful technique to investigate the atomic and electronic configuration around implanted atoms. The physics of dilute atoms in materials, the final lattice sites and their chemical state as well as diffusion phenomena can be studied. We focus on the latest developments of implantation Mössbauer spectroscopy, where three accelerator facilities, i.e., Hahn-Meitner Institute Berlin, ISOLDE-CERN and RIKEN, have intensively been used for materials research in in-beam and on-line Mössbauer experiments immediately after implantation of the nuclear probes.

  5. Dental Implants

    MedlinePlus Videos and Cool Tools

    ... facts so you can make an informed decision as to whether dental implants are right for your ... the jaw bone. It’s obviously not the same as the original connection , but functions just the same. ...

  6. Cochlear Implants

    MedlinePlus

    ... additional visits are needed for activating, adjusting, and programming the various electrodes that have been implanted. Also, ... to the center for checkups once the final programming is made to the speech processor. Both children ...

  7. Histrelin Implant

    MedlinePlus

    ... bone growth and development of sexual characteristics) in girls usually between 2 and 8 years of age ... MRI scans (radiology techniques designed to show the images of body structures) to find the implant when ...

  8. 16. VIEW LOOKING NORTHEAST AT BUILDING 11 (111) IN 1952. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. VIEW LOOKING NORTHEAST AT BUILDING 11 (111) IN 1952. IN 1952, BUILDINGS 11 (111), 12 (121), 21 (221), 22 (122), 23 (123), AND 42 (442) WERE OCCUPIED. BUILDINGS 91 (991) AND 81 (881) WERE OPERATIONAL. BUILDINGS 44 (444) AND 71 (771) WERE UNDER CONSTRUCTION. THE TOTAL COST FOR CONSTRUCTION BY 1952 WAS $2.5 MILLION. BY SEPTEMBER OF 1953, AUSTIN COMPANY HAD COMPLETED 21 BUILDINGS FOR AN APPROXIMATE COST OF $43.3 MILLION (1952). - Rocky Flats Plant, Bounded by Indiana Street & Routes 93, 128 & 72, Golden, Jefferson County, CO

  9. In situ 111In-doping for achieving biocompatible and non-leachable 111In-labeled Fe3O4 nanoparticles.

    PubMed

    Zeng, Jianfeng; Jia, Bing; Qiao, Ruirui; Wang, Chao; Jing, Lihong; Wang, Fan; Gao, Mingyuan

    2014-02-28

    The present study reports a new approach for synthesizing (111)In-radiolabeled biocompatible Fe3O4 nanoparticles. Radioactive (111)In is doped in situ into the lattice of Fe3O4 nanoparticles to achieve robust radiolabeling for accurately tracing PEGylated Fe3O4 particles in vivo. PMID:24430864

  10. Defects in ZnO

    NASA Astrophysics Data System (ADS)

    McCluskey, M. D.; Jokela, S. J.

    2009-10-01

    Zinc oxide (ZnO) is a wide band gap semiconductor with potential applications in optoelectronics, transparent electronics, and spintronics. The high efficiency of UV emission in this material could be harnessed in solid-state white lighting devices. The problem of defects, in particular, acceptor dopants, remains a key challenge. In this review, defects in ZnO are discussed, with an emphasis on the physical properties of point defects in bulk crystals. As grown, ZnO is usually n-type, a property that was historically ascribed to native defects. However, experiments and theory have shown that O vacancies are deep donors, while Zn interstitials are too mobile to be stable at room temperature. Group-III (B, Al, Ga, and In) and H impurities account for most of the n-type conductivity in ZnO samples. Interstitial H donors have been observed with IR spectroscopy, while substitutional H donors have been predicted from first-principles calculations but not observed directly. Despite numerous reports, reliable p-type conductivity has not been achieved. Ferromagnetism is complicated by the presence of secondary phases, grain boundaries, and native defects. The famous green luminescence has several possible origins, including Cu impurities and Zn vacancies. The properties of group-I (Cu, Li, and Na) and group-V (N, P, As, and Sb) acceptors, and their complexes with H, are discussed. In the future, doping of ZnO nanocrystals will rely on an understanding of these fundamental properties.

  11. The Hg isoelectronic defect in ZnO

    SciTech Connect

    Cullen, J.; McGlynn, E. Henry, M. O.; Johnston, K.; Dunker, D.; Bayer, M.; Yakovlev, D. R.

    2013-11-21

    We report a study of the luminescence due to Hg in ZnO, concentrating on the main zero phonon line (ZPL) at 3.2766(1) eV and its associated phonon sidebands. For a sample implanted with radioactive {sup 192}Hg, the ZPL intensity, normalised to that of shallow bound exciton emission, is observed to decrease with an equivalent half-life of 4.5(1) h, very close to the 4.85(20) h half-life of {sup 192}Hg. ZnO implanted with stable Hg impurities produces the same luminescence spectrum. Temperature dependent measurements confirm that the zero phonon line is a thermalizing doublet involving one allowed and one largely forbidden transition from excited states separated by 0.91(1) meV to a common ground state. Uniaxial stress measurements show that the allowed transition takes place from an orbitally degenerate excited state to a non-degenerate ground state in a centre of trigonal (C{sub 3v}) symmetry while the magneto-optical properties are characteristic of electron-hole pair recombination at an isoelectronic defect. The doublet luminescence is assigned to bound exciton recombination involving exchange-split Γ{sub 5} and Γ{sub 1,2} excited states (using C{sub 6v} symmetry labels; Γ{sub 3} and Γ{sub 1,2} using C{sub 3v} labels) at isoelectronic Hg impurities substituting for Zn in the crystal. The electron and hole g values deduced from the magneto-optical data indicate that this Hg impurity centre in ZnO is hole-attractive.

  12. The Hg isoelectronic defect in ZnO

    NASA Astrophysics Data System (ADS)

    Cullen, J.; Johnston, K.; Dunker, D.; McGlynn, E.; Yakovlev, D. R.; Bayer, M.; Henry, M. O.

    2013-11-01

    We report a study of the luminescence due to Hg in ZnO, concentrating on the main zero phonon line (ZPL) at 3.2766(1) eV and its associated phonon sidebands. For a sample implanted with radioactive 192Hg, the ZPL intensity, normalised to that of shallow bound exciton emission, is observed to decrease with an equivalent half-life of 4.5(1) h, very close to the 4.85(20) h half-life of 192Hg. ZnO implanted with stable Hg impurities produces the same luminescence spectrum. Temperature dependent measurements confirm that the zero phonon line is a thermalizing doublet involving one allowed and one largely forbidden transition from excited states separated by 0.91(1) meV to a common ground state. Uniaxial stress measurements show that the allowed transition takes place from an orbitally degenerate excited state to a non-degenerate ground state in a centre of trigonal (C3v) symmetry while the magneto-optical properties are characteristic of electron-hole pair recombination at an isoelectronic defect. The doublet luminescence is assigned to bound exciton recombination involving exchange-split Γ5 and Γ1,2 excited states (using C6v symmetry labels; Γ3 and Γ1,2 using C3v labels) at isoelectronic Hg impurities substituting for Zn in the crystal. The electron and hole g values deduced from the magneto-optical data indicate that this Hg impurity centre in ZnO is hole-attractive.

  13. Electrical properties of ZnO single nanowires

    NASA Astrophysics Data System (ADS)

    Stiller, Markus; Barzola-Quiquia, José; Zoraghi, Mahsa; Esquinazi, Pablo

    2015-10-01

    We have investigated the electrical resistance R(T) of ZnO nanowires of ≈ 400 nm diameter as a function of temperature, between 30 K and 300 K, and frequency in the range 40 Hz to 30 MHz. The measurements were done on the as-prepared and after low-energy proton implantation at room temperature. The temperature dependence of the resistance of the wire, before proton implantation, can be well described by two processes in parallel. One process is the fluctuation induced tunneling conductance (FITC) and the other the usual thermally activated process. The existence of a tunneling conductance was also observed in the current-voltage (I-V) results, and can be well described by the FITC model. Impedance spectroscopy measurements in the as-prepared state and at room temperature, indicate and support the idea of two contributions of these two transport processes in the nanowires. Electron backscatter diffraction confirms the existence of different crystalline regions. After the implantation of H+ a third thermally activated process is found that can be explained by taking into account the impurity band splitting due to proton implantation.

  14. Al-doped ZnO nanocrystals

    NASA Astrophysics Data System (ADS)

    Kadam, Pratibha; Agashe, Chitra; Mahamuni, Shailaja

    2008-11-01

    Al3+-doped ZnO nanocrystals were differently obtained by wet chemical and an electrochemical route. An increase in forbidden gap due to change in crystal size and also due to Al3+ doping in ZnO is critically analyzed. The Moss-Burstein type shift in Al3+-doped ZnO nanocrystals provides an evidence of successful Al3+ doping in ZnO nanocrystals. The possibility of varying the carrier concentration in ZnO nanocrystals is the indirect implication of the present investigations.

  15. A Comparison of ZnO and ZnO(-)

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Partridge, Harry; Arnold, James (Technical Monitor)

    1998-01-01

    Ab initio electronic structure calculations are performed to support and to help interpret the experimental work reported in the proceeding manuscript. The CCSD(T) approach, in conjunction with a large basis set, is used to compute spectroscopic constants for the X(exp 1)Epsilon(+) and (3)II states of ZnO and the X(exp 2)Epsilon(+) state of ZnO(-). The spectroscopic constants, including the electron affinity, are in good agreement with experiment. The ZnO EA is significantly larger than that of O, thus relative to the atomic ground state asymptotes, ZnO(-) has a larger D(sub o) than the (1)Epsilon(+) state, despite the fact that the extra electron goes into an antibonding orbital. The changes in spectroscopic constants can be understood in terms of the X(exp 1)Epsilon(+) formally dissociating to Zn (1)S + O (1)D while the (3)II and (2)Epsilon(+) states dissociate to Zn (1)S + O (3)P and Zn (1) and O(-) (2)P, respectively.

  16. Nonstoichiometric zinc oxide and indium-doped zinc oxide: Electrical conductivity and {sup 111}In-TDPAC studies

    SciTech Connect

    Wang, R.; Sleight, A.W.; Platzer, R.; Gardner, J.A.

    1996-02-15

    Indium-doped zinc oxide powders have been prepared which show room-temperature electrical conductivities as high as 30 {Omega}{sup {minus}1} cm{sup {minus}1}. The indium doping apparently occurs as Zn{sub 1-x}In{sub x}O,Zn{sub 1-y}In{sub y}O{sub 1+y/2}, or a combination of these. Optimum conductivity occurs for Zn{sub 1-x}In{sub x}O where the maximum value of x obtained was about 0.5 at%. The degrees of sample reduction were determined by iodimetric titration. Time differential perturbed angular correlation (TDPAC) spectroscopy on indium doped zinc oxide is consistent with indium substituting at normal zinc sites in the ZnO lattice. TDPAC studies on zinc oxide annealed under zinc vapors show a second environment for the {sup 111}In probe. In this case, there is an unusually high temperature dependence of the electric field gradient which may be caused by a nearby zinc interstitial. An important conclusion of this work is that zinc interstitials are not ionized and do not therefore contribute significantly to the increased conductivity of reduced zinc oxide.

  17. Flexible, transparent and exceptionally high power output nanogenerators based on ultrathin ZnO nanoflakes

    NASA Astrophysics Data System (ADS)

    van Ngoc, Huynh; Kang, Dae Joon

    2016-02-01

    Novel nanogenerator structures composed of ZnO nanoflakes of less than 10 nm thickness were fabricated using a novel method involving a facile synthetic route and a rational design. The fabricated nanogenerators exhibited a short-circuit current density of 67 μA cm-2, a peak-to-peak open-circuit voltage of 110 V, and an overall output power density exceeding 1.2 mW cm-2, and to the best of our knowledge, these are the best values that have been reported so far in the literature on ZnO-based nanogenerators. We demonstrated that our nanogenerator design could instantaneously power 20 commercial green light-emitting diodes without any additional energy storage processes. Both the facile synthetic route for the ZnO nanoflakes and the straightforward device fabrication process present great scaling potential in order to power mobile and personal electronics that can be used in smart wearable systems, transparent and flexible devices, implantable telemetric energy receivers, electronic emergency equipment, and other self-powered nano/micro devices.Novel nanogenerator structures composed of ZnO nanoflakes of less than 10 nm thickness were fabricated using a novel method involving a facile synthetic route and a rational design. The fabricated nanogenerators exhibited a short-circuit current density of 67 μA cm-2, a peak-to-peak open-circuit voltage of 110 V, and an overall output power density exceeding 1.2 mW cm-2, and to the best of our knowledge, these are the best values that have been reported so far in the literature on ZnO-based nanogenerators. We demonstrated that our nanogenerator design could instantaneously power 20 commercial green light-emitting diodes without any additional energy storage processes. Both the facile synthetic route for the ZnO nanoflakes and the straightforward device fabrication process present great scaling potential in order to power mobile and personal electronics that can be used in smart wearable systems, transparent and flexible

  18. Cochlear Implants

    MedlinePlus

    ... outside of the body, behind the ear. A second part is surgically placed under the skin. An implant does not restore normal hearing. It can help a person understand speech. Children and adults can benefit from them. National Institute on Deafness and Other Communication Disorders

  19. Cochlear implant

    MedlinePlus

    ... are sent along the auditory nerve to the brain. A deaf person does not have a functioning inner ear. A cochlear implant tries to replace the function of the inner ear by ... signals to the brain. Sound is picked up by a microphone worn ...

  20. Acceptors in ZnO

    SciTech Connect

    McCluskey, Matthew D. Corolewski, Caleb D.; Lv, Jinpeng; Tarun, Marianne C.; Teklemichael, Samuel T.; Walter, Eric D.; Norton, M. Grant; Harrison, Kale W.; Ha, Su

    2015-03-21

    Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on acceptors. In this paper, Cu, N, and Li acceptor impurities are discussed. Experimental evidence indicates these point defects have acceptor levels 3.2, 1.4, and 0.8 eV above the valence-band maximum, respectively. The levels are deep because the ZnO valence band is quite low compared to conventional, non-oxide semiconductors. Using MoO{sub 2} contacts, the electrical resistivity of ZnO:Li was measured and showed behavior consistent with bulk hole conduction for temperatures above 400 K. A photoluminescence peak in ZnO nanocrystals is attributed to an acceptor, which may involve a Zn vacancy. High field (W-band) electron paramagnetic resonance measurements on the nanocrystals revealed an axial center with g{sub ⊥} = 2.0015 and g{sub //} = 2.0056, along with an isotropic center at g = 2.0035.

  1. Acceptors in ZnO

    SciTech Connect

    Mccluskey, Matthew D.; Corolewski, Caleb; Lv, Jinpeng; Tarun, Marianne C.; Teklemichael, Samuel T.; Walter, Eric D.; Norton, M. G.; Harrison, Kale W.; Ha, Su Y.

    2015-03-21

    Zinc oxide (ZnO) has potential for a range of applications in the area of optoelectronics. The quest for p-type ZnO has focused much attention on acceptors. In this paper, Cu, N, and Li acceptor impurities are discussed. Experimental evidence shows that these point defects have acceptor levels 3.2, 1.5, and 0.8 eV above the valence-band maximum, respectively. The levels are deep because the ZnO valence band is quite low compared to conventional, non-oxide semiconductors. Using MoO2 contacts, the electrical resistivity of ZnO:Li was measured and showed behavior consistent with bulk hole conduction for temperatures above 400 K. A photoluminescence peak in ZnO nanocrystals has been attributed to an acceptor, which may involve a zinc vacancy. High field (W-band) electron paramagnetic resonance measurements on the nanocrystals revealed an axial center with g = 2.0033 and g = 2.0075, along with an isotropic center at g = 2.0053.

  2. Homoepitaxial ZnO Film Growth

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C-H; Lehoczky, S. L.; Harris, M. T.; Callahan, M. J.; McCarty, P.; George, M. A.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    ZnO films have high potential for many applications, such as surface acoustic wave filters, UV detectors, and light emitting devices due to its structural, electrical, and optical properties. High quality epitaxial films are required for these applications. The Al2O3 substrate is commonly used for ZnO heteroepitaxial growth. Recently, high quality ZnO single crystals are available for grow homoepitaxial films. Epitaxial ZnO films were grown on the two polar surfaces (O-face and Zn-face) of (0001) ZnO single crystal substrates using off-axis magnetron sputtering deposition. As a comparison, films were also deposited on (0001) Al2O3 substrates. It was found that the two polar ZnO surfaces have different photoluminescence (PL) spectrum, surface structure and morphology, which strongly influence the epitaxial film growth. The morphology and structure of homoepitaxial films grown on the ZnO substrates were different from heteroepitaxial films grown on the Al2O3. An interesting result shows that high temperature annealing of ZnO single crystals will improve the surface structure on the O-face surface rather than the opposite surface. The measurements of PL, low-angle incident x-ray diffraction, and atomic force microscopy of ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth.

  3. Preparation of new morphological ZnO and Ce-doped ZnO

    SciTech Connect

    Chelouche, A.; Djouadi, D.; Aksas, A.

    2013-12-16

    ZnO micro-tori and cerium doped hexangulars ZnO have been prepared by the sol-gel method under methanol hypercritical conditions of temperature and pressure. X-ray diffraction (XRD) measurement has revealed the high crystalline quality and the nanometric size of the samples. Scanning electron microscopy (SEM) has shown that the ZnO powder has a torus-like shape while that of ZnO:Ce has a hexangular-like shape, either standing free or inserted into the cores of ZnO tori. Transmission electron microscopy (TEM) has revealed that the ZnO particles have sizes between 25 and 30 nm while Ce-doped ZnO grains have diameters ranging from 75 nm to 100 nm. Photoluminescence spectra at room temperature of the samples have revealed that the introduction of cerium in ZnO reduces the emission intensity lines, particularly the ZnO red and green ones.

  4. p type doping of zinc oxide by arsenic ion implantation

    SciTech Connect

    Braunstein, G.; Muraviev, A.; Saxena, H.; Dhere, N.; Richter, V.; Kalish, R.

    2005-11-07

    p type doping of polycrystalline ZnO thin films, by implantation of arsenic ions, is demonstrated. The approach consisted of carrying out the implantations at liquid-nitrogen temperature ({approx}-196 deg. C), followed by a rapid in situ heating of the sample, at 560 deg. C for 10 min, and ex situ annealing at 900 deg. C for 45 min in flowing oxygen. p type conductivity with a hole concentration of 2.5x10{sup 13} cm{sup -2} was obtained using this approach, following implantation of 150 keV 5x10{sup 14} As/cm{sup 2}. A conventional room-temperature implantation of 1x10{sup 15} As/cm{sup 2}, followed by the same ex situ annealing, resulted in n type conductivity with a carrier concentration of 1.7x10{sup 12} cm{sup -2}.

  5. Effect of ZnO morphology on affecting bactericidal property of ultra high molecular weight polyethylene biocomposite.

    PubMed

    Sharma, Rajeev Kumar; Agarwal, Meenakshi; Balani, Kantesh

    2016-05-01

    Bacterial infection of implants can be controlled by selective trapping of bacteria, followed with consequent killing by targeted antibacterial agents. Herein, the role of various ZnO morphologies, viz. micro-rods (R), nanoparticles (NP), and micro-disks (D) on antibacterial efficacy of ZnO via release of Zn(2+) and H2O2 is assessed, both as isolated powders and via incorporating them in cytocompatible ultra high molecular weight polyethylene (UHMWPE). Though ZnO is antibacterial, interestingly, all ZnO morphologies elicited a supportive growth of gram-negative bacteria (Escherichia coli) in culture medium (until 28-35μg/ml). But, all ZnO morphologies did elicit bactericidal effect on gram positive bacteria (Staphylococcus aureus or Staphylococcus epidermidis) both in culture medium (for 0-2.5μg/ml) or when incorporated (5-20wt.%) into UHMWPE. The bactericidal mechanisms were quantified for various ZnO morphologies via: (i) H2O2 production, (ii) Zn(2+) release, and (iii) the presence of surface oxygen vacancies. On one hand, where only ZnO(NP) elicited release of H2O2 in the absence of light, maximum Zn(2+) release was elicited by ZnO(D). Interestingly, when ZnO is incorporated as reinforcement (5-20wt.%), its antibacterial action against E. coli was vividly observed due to selective proliferation of bacteria only on friendly UHMWPE matrix. Hence, luring bacteria on affable UHMWPE surface can be complemented with their targeted killing by ZnO present in composite. PMID:26952491

  6. Room Temperature Ferromagnetism in Transition Metal Doped CVD-Grown ZnO Films and Nanostructures

    NASA Astrophysics Data System (ADS)

    Hill, D. H.; Gateau, R.; Bartynski, R. A.; Wu, P.; Lu, Y.; Wielunski, L.; Poltavets, V.; Greenblatt, M.; Arena, D. A.; Dvorak, J.; Calvin, S.

    2006-03-01

    We have characterized the chemical, compositional, and magnetic properties of Mn- and Fe-ion implanted epitaxial ZnO films and single crystal nanostructures grown by MOCVD as candidate room temperature diluted magnetic semiconductors. X-ray absorption spectroscopy (SXAS) shows that Mn-implanted films contain Mn^2+ ions which convert to a mixture of Mn^3+ and Mn^4+ upon annealing. Fe-implanted films contain a mixture of Fe^2+ and Fe^3+ which converts to a higher concentration of Fe^3+ upon annealing. XAS and preliminary analysis of EXAFS data indicate that the TM ions are substitutional for Zn. SQUID magnetometry shows that as-implanted films are ferromagnetic at 5K and the annealed films are ferromagnetic at room temperature. X-ray diffraction shows that the annealed films remain epitaxial with excellent long range order. Rutherford backscattering spectrometry indicates a substantial recovery of local order upon annealing as well. The properties of in-situ Fe-doped MOCVD-grown ZnO epitaxial films and nanostructures will also be discussed.

  7. Impurity sublattice localization in ZnO revealed by Li marker diffusion.

    PubMed

    Azarov, A Yu; Knutsen, K E; Neuvonen, P T; Vines, L; Svensson, B G; Kuznetsov, A Yu

    2013-04-26

    Sublattice localization of impurities in compound semiconductors, e.g., ZnO, determines their electronic and optical action. Despite that the impurity position may be envisaged based on charge considerations, the actual localization is often unknown, limiting our understanding of the incorporation and possible doping mechanisms. In this study, we demonstrate that the preferential sublattice occupation for a number of impurities in ZnO can be revealed by monitoring Li diffusion. In particular, using ion implantation, the impurity incorporation into the Zn sublattice (holds for, B, Mg, P, Ag, Cd, and Sb) manifests in the formation of Li-depleted regions behind the implanted one, while Li pileups in the region of the implantation peaks for impurities residing on O sites, e.g., N. The behavior appears to be of general validity and the phenomena are explained in terms of the apparent surplus of Zn and O interstitials, related to the lattice localization of the impurities. Furthermore, Cd+O and Mg+O co-doping experiments revealed that implanted O atoms act as an efficient blocking "filter" for fast diffusing Zn interstitials. PMID:23679745

  8. Acceptor Type Vacancy Complexes In As-Grown ZnO

    SciTech Connect

    Zubiaga, A.; Tuomisto, F.; Zuniga-Perez, J.

    2010-11-01

    One of the many technological areas that ZnO is interesting for is the construction of opto-electronic devices working in the blue-UV range as its large band gap ({approx}3.4 eV at 10 K) makes them suitable for that purpose. As-grown ZnO shows generally n-type conductivity partially due to the large concentration of unintentional shallow donors, like H, but impurities can also form complexes with acceptor type defects (Zn vacancy) leading to the creation of compensating defects. Recently, Li{sub Zn} and Na{sub Zn} acceptors have been measured and H could form similar type of defects. Doppler Broadening Positron Annihilation spectroscopy experimental results on the observation of Zn related vacancy complexes in ZnO thin films, as-grown, O implanted and Al doped will be presented. Results show that as-grown ZnO film show small Zn vacancy related complexed that could be related to presence of H as a unintentional doping element.

  9. NEXAFS and XMCD studies of single-phase Co doped ZnO thin films.

    PubMed

    Singh, Abhinav Pratap; Kumar, Ravi; Thakur, P; Brookes, N B; Chae, K H; Choi, W K

    2009-05-01

    A study of the electronic structure and magnetic properties of Co doped ZnO thin films synthesized by ion implantation followed by swift heavy ion irradiation is presented using near-edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) measurements. The spectral features of NEXAFS at the Co L(3,2)-edge show entirely different features than that of metallic Co clusters and other Co oxide phases. The atomic multiplet calculations are performed to determine the valence state, symmetry and the crystal field splitting, which show that in the present system Co is in the 2+ state and substituted at the Zn site in tetrahedral symmetry with 10Dq = -0.6 eV. The ferromagnetic character of these materials is confirmed through XMCD spectra. To rule out the possibilities of defect induced magnetism, the results are compared with Ar annealed and Ar-ion implanted pure ZnO thin films. The presented results confirm the substitution of Co at the Zn site in the ZnO matrix, which is responsible for room temperature ferromagnetism. PMID:21825451

  10. Gold coated ZnO nanorod biosensor for glucose detection

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Anuradha; Jain, Chhavi; Rao, V. Padmanapan; Banerjee, S.

    2012-06-01

    Gold coated ZnO nanorod based biosensor has been fabricated for its glucose detecting abilities and compared with that of ZnO nanorod based biosensor. SEM images of electrochemically grown ZnO nanorods show hexagonally grown ZnO nanorods on an ITO substrate. Electrochemical analysis show that gold coated ZnO based biosensors have higher sensitivity, lower limit of detection and a wider linear range for glucose detection. The results demonstrate that gold coated ZnO nanorod based biosensors are a promising material for biosensor applications over single component ZnO nanorod based biosensor.

  11. [Preparation of two poor water soluble drugs - nanoporous ZnO solid dispersions and the mechanism of drug dissolution improvement].

    PubMed

    Gao, Bei; Sun, Chang-shan; Zhi, Zhuang-zhi; Wang, Yan; Chang, Di; Wang, Si-ling; Jiang, Tong-ying

    2011-11-01

    Nanoporous ZnO was used as a carrier to prepare drug solid dispersion, the mechanism of which to improve the drug dissolution was also studied. Nanoporous ZnO, obtained through chemical deposition method, was used as a carrier to prepare indomethacin and cilostazol solid dispersions by melt-quenching method, separately. The results of scanning electron microscope, surface area analyzer, fourier transform infra-red spectroscopy, differential scanning calorimeter and X-ray diffraction showed that drugs were implanted into nanopores of ZnO by physical adsorption effect and highly dispersed into nanopores of ZnO in amorphous form, moreover, these nanopores strongly inhibited amorphous recrystallization in the condition of 45 degrees C and 75% RH. In addition, the results of the dissolution tested in vitro exhibited that the accumulated dissolutions of indomethacin and cilostazol solid dispersions achieved about 90% within 5 min and approximately 80% within 30 min. It was indicated in this study that the mechanism of drug dissolution improvement was associated with the effects of nanoporous ZnO carrier on increasing drug dispersion, controlling drug in nanopores as amorphous form and inhibiting amorphous recrystallization. PMID:22260037

  12. DFT study of the hyperfine parameters and magnetic properties of ZnO doped with 57Fe

    NASA Astrophysics Data System (ADS)

    Abreu, Y.; Cruz, C. M.; Piñera, I.; Leyva, A.; Cabal, A. E.; Van Espen, P.

    2014-05-01

    Magnetic state of 57Fe implanted and doped ZnO samples have been reported and studied by Mössbauer spectroscopy at different temperatures. The Mössbauer spectra mainly showed four doublets and three sextets, but some ambiguous identification remains regarding the probe site location and influence of defects in the hyperfine and magnetic parameters. In the present work some possible implantation configurations are suggested and evaluated using Monte Carlo simulation and electronic structure calculations within the density functional theory. Various implantation environments were proposed and studied considering the presence of defects. The obtained 57Fe hyperfine parameters show a good agreement with the reported experimental values for some of these configurations. The possibility of Fe pair formation, as well as a Zn site vacancy stabilization between the second and third neighborhood of the implantation site, is supported.

  13. N Doping to ZnO Nanorods for Photoelectrochemical Water Splitting under Visible Light: Engineered Impurity Distribution and Terraced Band Structure

    PubMed Central

    Wang, Meng; Ren, Feng; Zhou, Jigang; Cai, Guangxu; Cai, Li; Hu, Yongfeng; Wang, Dongniu; Liu, Yichao; Guo, Liejin; Shen, Shaohua

    2015-01-01

    Solution-based ZnO nanorod arrays (NRAs) were modified with controlled N doping by an advanced ion implantation method, and were subsequently utilized as photoanodes for photoelectrochemical (PEC) water splitting under visible light irradiation. A gradient distribution of N dopants along the vertical direction of ZnO nanorods was realized. N doped ZnO NRAs displayed a markedly enhanced visible-light-driven PEC photocurrent density of ~160 μA/cm2 at 1.1 V vs. saturated calomel electrode (SCE), which was about 2 orders of magnitude higher than pristine ZnO NRAs. The gradiently distributed N dopants not only extended the optical absorption edges to visible light region, but also introduced terraced band structure. As a consequence, N gradient-doped ZnO NRAs can not only utilize the visible light irradiation but also efficiently drive photo-induced electron and hole transfer via the terraced band structure. The superior potential of ion implantation technique for creating gradient dopants distribution in host semiconductors will provide novel insights into doped photoelectrode materials for solar water splitting. PMID:26262752

  14. N Doping to ZnO Nanorods for Photoelectrochemical Water Splitting under Visible Light: Engineered Impurity Distribution and Terraced Band Structure.

    PubMed

    Wang, Meng; Ren, Feng; Zhou, Jigang; Cai, Guangxu; Cai, Li; Hu, Yongfeng; Wang, Dongniu; Liu, Yichao; Guo, Liejin; Shen, Shaohua

    2015-01-01

    Solution-based ZnO nanorod arrays (NRAs) were modified with controlled N doping by an advanced ion implantation method, and were subsequently utilized as photoanodes for photoelectrochemical (PEC) water splitting under visible light irradiation. A gradient distribution of N dopants along the vertical direction of ZnO nanorods was realized. N doped ZnO NRAs displayed a markedly enhanced visible-light-driven PEC photocurrent density of ~160 μA/cm(2) at 1.1 V vs. saturated calomel electrode (SCE), which was about 2 orders of magnitude higher than pristine ZnO NRAs. The gradiently distributed N dopants not only extended the optical absorption edges to visible light region, but also introduced terraced band structure. As a consequence, N gradient-doped ZnO NRAs can not only utilize the visible light irradiation but also efficiently drive photo-induced electron and hole transfer via the terraced band structure. The superior potential of ion implantation technique for creating gradient dopants distribution in host semiconductors will provide novel insights into doped photoelectrode materials for solar water splitting. PMID:26262752

  15. Retrograde peri-implantitis.

    PubMed

    Mohamed, Jumshad B; Shivakumar, B; Sudarsan, Sabitha; Arun, K V; Kumar, T S S

    2010-01-01

    Retrograde peri-implantitis constitutes an important cause for implant failure. Retrograde peri-implantitis may sometimes prove difficult to identify and hence institution of early treatment may not be possible. This paper presents a report of four cases of (the implant placed developing to) retrograde peri-implantitis. Three of these implants were successfully restored to their fully functional state while one was lost due to extensive damage. The paper highlights the importance of recognizing the etiopathogenic mechanisms, preoperative assessment, and a strong postoperative maintenance protocol to avoid retrograde peri-implant inflammation. PMID:20922082

  16. Diagnosis of osteomyelitis of the foot in diabetic patients: Value of 111In-leukocyte scintigraphy

    SciTech Connect

    Larcos, G.; Brown, M.L.; Sutton, R.T. )

    1991-09-01

    The noninvasive diagnosis of osteomyelitis of the foot in diabetic patients with currently available radiologic and radionuclide imaging techniques is often difficult. Recently, 111In-labeled leukocyte scintigraphy has been proposed as an attractive alternative. Accordingly, the authors retrospectively reviewed 51 111In-labeled leukocyte scans, 49 technetium-99m bone scans, and 49 plain radiographs obtained in 51 adults with diabetes in whom osteomyelitis of the foot was suspected. The sensitivity and specificity of these techniques were evaluated in all patients, as well as in a subgroup of 11 patients with neuroarthropathy. Results with 111In-labeled leukocyte scans were also examined in subsets of patients with soft-tissue ulcers (n = 35) and those receiving antibiotics during investigation (n = 20). Confirmation or exclusion of osteomyelitis was made surgically in 28 patients and clinically in 23. Fourteen patients had osteomyelitis. Bone scans were most sensitive (93%) but least specific (43%); plain radiographs were most specific (83%) but least sensitive (43%). 111In-labeled leukocyte scans were both sensitive (79%) and specific (78%), and remained useful in patients with neuroarthropathy, soft-tissue ulcers, and antibiotic treatment. Poor spatial resolution contributed to the false-negative and false-positive 111In-labeled leukocyte scans, suggesting that this technique should not be interpreted independent of other tests. 111In-labeled leukocyte scans are a valuable diagnostic tool for the diagnosis of pedal osteomyelitis in diabetic patients.

  17. Evaluation in a Dog Model of Three Antimicrobial Glassy Coatings: Prevention of Bone Loss around Implants and Microbial Assessments

    PubMed Central

    López-Píriz, Roberto; Solá-Linares, Eva; Rodriguez-Portugal, Mercedes; Malpica, Beatriz; Díaz-Güemes, Idoia; Enciso, Silvia; Esteban-Tejeda, Leticia; Cabal, Belén; Granizo, Juan José; Moya, José Serafín; Torrecillas, Ramón

    2015-01-01

    Objectives The aim of the present study is to evaluate, in a ligature-induced peri-implantitis model, the efficacy of three antimicrobial glassy coatings in the prevention of biofilm formation, intrasulcular bacterial growth and the resulting peri-implant bone loss. Methods Mandibular premolars were bilaterally extracted from five beagle dogs. Four dental implants were inserted on each hemiarch. Eight weeks after, one control zirconia abutment and three with different bactericidal coatings (G1n-Ag, ZnO35, G3) were connected. After a plaque control period, bacterial accumulation was allowed and biofilm formation on abutments was observed by Scanning Electron Microscopy (SEM). Peri-implantitis was induced by cotton ligatures. Microbial samples and peri-implant crestal bone levels of all implant sites were obtained before, during and after the breakdown period. Results During experimental induce peri-implantitis: colony forming units counts from intrasulcular microbial samples at implants with G1n-Ag coated abutment remained close to the basal inoculum; G3 and ZnO35 coatings showed similar low counts; and anaerobic bacterias counts at control abutments exhibited a logarithmic increase by more than 2. Bone loss during passive breakdown period was no statistically significant. Additional bone loss occurred during ligature-induce breakdown: 0.71 (SD 0.48) at G3 coating, 0.57 (SD 0.36) at ZnO35 coating, 0.74 (SD 0.47) at G1n-Ag coating, and 1.29 (SD 0.45) at control abutments; and statistically significant differences (p<0.001) were found. The lowest bone loss at the end of the experiment was exhibited by implants dressing G3 coated abutments (mean 2.1; SD 0.42). Significance Antimicrobial glassy coatings could be a useful tool to ward off, diminish or delay peri-implantitis progression. PMID:26489088

  18. Spinel ferrite nanocrystals embedded inside ZnO: Magnetic, electronic, and magnetotransport properties

    NASA Astrophysics Data System (ADS)

    Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Markó, D.; Mücklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.; Schmidt, H.

    2009-09-01

    In this paper we show that spinel ferrite nanocrystals ( NiFe2O4 , and CoFe2O4 ) can be texturally embedded inside a ZnO matrix by ion implantation and postannealing. The two kinds of ferrites show different magnetic properties, e.g., coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magnetoelectronics. This hybrid system can be tuned by selecting different transition-metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.

  19. Spinel ferrite nanocrystals embedded inside ZnO: magnetic, electronic andmagneto-transport properties

    SciTech Connect

    Zhou, Shengqiang; Potzger, K.; Xu, Qingyu; Kuepper, K.; Talut, G.; Marko, D.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.; Schmidt, H.

    2009-08-21

    In this paper we show that spinel ferrite nanocrystals (NiFe{sub 2}O{sub 4}, and CoFe{sub 2}O{sub 4}) can be texturally embedded inside a ZnO matrix by ion implantation and post-annealing. The two kinds of ferrites show different magnetic properties, e.g. coercivity and magnetization. Anomalous Hall effect and positive magnetoresistance have been observed. Our study suggests a ferrimagnet/semiconductor hybrid system for potential applications in magneto-electronics. This hybrid system can be tuned by selecting different transition metal ions (from Mn to Zn) to obtain various magnetic and electronic properties.

  20. High-temperature ferromagnetism in transition metal implanted wide-bandgap semiconductors

    NASA Astrophysics Data System (ADS)

    Raley, Jeremy A.

    The field of spin transport electronics (spintronics) is a viable candidate for advancing computing and communication technologies. Material with both semiconductor and magnetic properties, which is commonly called a dilute magnetic semiconductor (DMS), will prove most useful in the fabrication of spintronic devices. In order to produce a DMS at above room temperature, transition metals (TMs) were implanted into host semiconductors of p-GaN, Al0.35Ga0.65N, or ZnO. Magnetic hysteresis measurements using a superconducting quantum interference device (SQUID) magnetometer show that some of the material combinations clearly exhibit ferromagnetism above room temperature. The most promising materials for creating spintronic devices using ion implantation are p-GaN:Mn, Al0.35Ga0.65N:Cr, and Fe-implanted ZnO nanotips on Al2O3. Temperature-dependent magnetization measurements confirm that indications of ferromagnetism are due to DMS behavior. Photo- and cathodoluminescence measurements show that implantation damage is recovered and the implanted TMs are incorporated into the semiconductor. As progress is made toward realizing practical spintronic devices, the work reported here will be useful for determining material combinations and implantation conditions that will yield the needed materials.

  1. The nitridation of ZnO nanowires

    PubMed Central

    2012-01-01

    ZnO nanowires (NWs) with diameters of 50 to 250 nm and lengths of several micrometres have been grown by reactive vapour transport via the reaction of Zn with oxygen on 1 nm Au/Si(001) at 550°C under an inert flow of Ar. These exhibited clear peaks in the X-ray diffraction corresponding to the hexagonal wurtzite crystal structure of ZnO and a photoluminescence spectrum with a peak at 3.3 eV corresponding to band edge emission close to 3.2 eV determined from the abrupt onset in the absorption-transmission through ZnO NWs grown on 0.5 nm Au/quartz. We find that the post growth nitridation of ZnO NWs under a steady flow of NH3 at temperatures ≤600°C promotes the formation of a ZnO/Zn3N2 core-shell structure as suggested by the suppression of the peaks related to ZnO and the emergence of new ones corresponding to the cubic crystal structure of Zn3N2 while maintaining their integrity. Higher temperatures lead to the complete elimination of the ZnO NWs. We discuss the effect of nitridation time, flow of NH3, ramp rate and hydrogen on the conversion and propose a mechanism for the nitridation. PMID:22397754

  2. Fabrication of ZnO nanoparticles by laser ablation of sintered ZnO in aqueous solution

    NASA Astrophysics Data System (ADS)

    Kawabata, Keisuke; Nanai, Yasushi; Kimura, Seiji; Okuno, Tsuyoshi

    2012-04-01

    Fabrication of ZnO nanoparticles by laser ablation in liquid medium is reported. The possibility of using a sintered ZnO target for the ablation as well as a Zn plate is demonstrated. The appropriate aqueous solution of sodium dodecyl sulfate is found to be 1 mM for ZnO growing. The shape of ZnO nanoparticles is sphere and its diameter is 30˜60 nm. Fourier transform infrared spectra, Raman scattering spectra, and photoluminescence spectra reveal the optical properties of ZnO nanoparticles. Nanoparticles obtained by using ZnO targets show a smaller defect density compared with those by using Zn targets.

  3. Sensitivity of 57Fe emission Mössbauer spectroscopy to Ar and C induced defects in ZnO

    NASA Astrophysics Data System (ADS)

    Bharuth-Ram, K.; Mølholt, T. E.; Langouche, G.; Geburt, S.; Ronning, C.; Doyle, T. B.; Gunnlaugsson, H. P.; Johnston, K.; Mantovan, R.; Masenda, H.; Naidoo, D.; Ncube, M.; Gislason, H.; Ólafsson, S.; Weyer, G.

    2016-12-01

    Emission Mössbauer Spectroscopy (eMS) measurements, following low fluence (<1012 cm-2) implantation of 57Mn (t 1/2 = 1.5 min.) into ZnO single crystals pre-implanted with Ar and C ions, has been utilized to test the sensitivity of the 57Fe eMS technique to the different types of defects generated by the different ion species. The dominant feature of the Mössbauer spectrum of the Ar implanted ZnO sample was a magnetic hyperfine field distribution component, attributed to paramagnetic Fe3+, while that of the C implanted sample was a doublet attributed to substitutional Fe2+ forming a complex with the C dopant ions in the 2- state at O vacancies. Magnetization measurements on the two samples, on the other hand, yield practically identical m(H) curves. The distinctly different eMS spectra of the two samples display the sensitivity of the probe nucleus to the defects produced by the different ion species.

  4. Emission channeling studies on transition-metal doped GaN and ZnO: Cation versus anion substitution

    NASA Astrophysics Data System (ADS)

    Pereira, L. M. C.; Wahl, U.; Correia, J. G.; Amorim, L. M.; Silva, D. J.; Decoster, S.; da Silva, M. R.; Temst, K.; Vantomme, A.

    2014-08-01

    The magnetic and electric properties of impurities in semiconductors are strongly dependent on the lattice sites which they occupy. While the majority site can often be predicted based on chemical similarities with the host elements and is usually simple to confirm experimentally, minority sites are far more complicated to predict, detect and identify. We have carried out extensive β- emission channeling studies on the lattice location of transition metal impurities in wide-gap dilute magnetic semiconductors, namely Co and Mn in GaN and ZnO, making use of radioactive 61Co and 56Mn implanted at the ISOLDE facility at CERN. In addition to the majority occupation of cation (Ga, Zn) sites, we located significant fractions (of the order of 20%) of the Co and Mn impurities in anion (N, O) sites, which are virtually unaffected by thermal annealing up to 900 °C. Here, we present the β- emission channeling experiments on 61Co-implanted GaN. We discuss these results in the context of our recent reports of minority anion substitution in Mn-implanted GaN Pereira et al. (2012) [19] and Mn/Co-implanted ZnO Pereira et al. (2011) [20], particularly in terms of the advantages of the emission channeling technique in such cases of multi-site occupancy.

  5. Growth of vertically aligned ZnO nanorods using textured ZnO films

    PubMed Central

    2011-01-01

    A hydrothermal method to grow vertical-aligned ZnO nanorod arrays on ZnO films obtained by atomic layer deposition (ALD) is presented. The growth of ZnO nanorods is studied as function of the crystallographic orientation of the ZnO films deposited on silicon (100) substrates. Different thicknesses of ZnO films around 40 to 180 nm were obtained and characterized before carrying out the growth process by hydrothermal methods. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc to provide nucleation sites for vertical nanorod growth. Crystallographic orientation of the ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. Composition, morphologies, length, size, and diameter of the nanorods were studied using a scanning electron microscope and energy dispersed x-ray spectroscopy analyses. In this work, it is demonstrated that crystallinity of the ZnO-ALD films plays an important role in the vertical-aligned ZnO nanorod growth. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as photosensitive materials in the manufacture of semiconductor-polymer solar cells. PACS 61.46.Hk, Nanocrystals; 61.46.Km, Structure of nanowires and nanorods; 81.07.Gf, Nanowires; 81.15.Gh, Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.) PMID:21899743

  6. sup 111 In-labeled nonspecific immunoglobulin scanning in the detection of focal infection

    SciTech Connect

    Rubin, R.H.; Fischman, A.J.; Callahan, R.J.; Khaw, B.A.; Keech, F.; Ahmad, M.; Wilkinson, R.; Strauss, H.W. )

    1989-10-05

    We performed radionuclide scanning after the intravenous injection of human IgG labeled with indium-111 in 128 patients with suspected focal sites of inflammation. Localization of 111In-labeled IgG correlated with clinical findings in 51 infected patients (21 with abdominal or pelvic infections, 11 with intravascular infections, 7 with pulmonary infections, and 12 with skeletal infections). Infecting organisms included gram-positive bacteria, gram-negative bacteria, Pneumocystis carinii, Mycoplasma pneumoniae, and Candida albicans. No focal localization of 111In-labeled IgG was observed in 63 patients without infection. There were five false negative results, and nine results were unusable. Serial scans were carried out in eight patients: continued localization correctly predicted relapse in six, and the absence of localization indicated resolution in two. To determine whether 111In-labeled IgG localization was specific for inflammation, we studied 16 patients with cancer. Focal localization occurred in 13 of these patients (5 with melanomas, 5 with gynecologic cancers, and 1 each with lymphoma, prostate cancer, and malignant fibrous histiocytoma). No localization was seen in patients with renal or colon cancer or metastatic medullary carcinoma of the thyroid. We conclude that 111In-labeled IgG imaging is effective for the detection of focal infection and that serial scans may be useful in assessing therapeutic efficacy. This technique may also be helpful in the evaluation of certain cancers.

  7. Urinary incontinence - injectable implant

    MedlinePlus

    Injectable implants are injections of material into the urethra to help control urine leakage ( urinary incontinence ) caused by a ... into the tissue next to the sphincter. The implant procedure is usually done in the hospital. Or ...

  8. Single ZnO nanocactus gas sensor formed by etching of ZnO nanorod

    NASA Astrophysics Data System (ADS)

    Ryong Ryu, Sung; Ram, S. D. Gopal; Cho, Hak-Dong; Lee, Dong Jin; Won Kang, Tae; Woo, Yongdeuk

    2015-06-01

    Etching of materials on the nanoscale is a challenging but necessary process in nanomaterials science. Gas sensing using a single ZnO nanocactus (NC), which was prepared by facile isotropic nanoetching of zinc oxide nanorods (NR) grown by chemical vapor deposition (CVD) using an organic photoresist (PR) by a thermochemical reaction, is reported in this work. PR consists of carboxylic acid groups (COOH) and cyclopentanone (C5H8O), which can react with zinc and oxygen atoms, respectively, on the surface of a ZnO NR. The thermochemical reaction is controllable by varying the concentration of PR and reaction time. A gas sensor was fabricated using a single NC. Gas sensing was tested using different gases such as CH4, NH3 and carbon monoxide (CO). It was estimated that the surface area of a ZnO NC in the case of 50% PR was found to increase four-fold. When compared with a single ZnO NR gas sensor, the sensitivity of a ZnO NC was found to increase four-fold. This increase in sensitivity is attributed to the increase in surface area of the ZnO NC. The formed single ZnO NC gas sensor has good stability, response and recovery time.Etching of materials on the nanoscale is a challenging but necessary process in nanomaterials science. Gas sensing using a single ZnO nanocactus (NC), which was prepared by facile isotropic nanoetching of zinc oxide nanorods (NR) grown by chemical vapor deposition (CVD) using an organic photoresist (PR) by a thermochemical reaction, is reported in this work. PR consists of carboxylic acid groups (COOH) and cyclopentanone (C5H8O), which can react with zinc and oxygen atoms, respectively, on the surface of a ZnO NR. The thermochemical reaction is controllable by varying the concentration of PR and reaction time. A gas sensor was fabricated using a single NC. Gas sensing was tested using different gases such as CH4, NH3 and carbon monoxide (CO). It was estimated that the surface area of a ZnO NC in the case of 50% PR was found to increase four

  9. Hair implant complications.

    PubMed

    Hanke, C W; Norins, A L; Pantzer, J G; Bennett, J E

    1981-04-01

    Four men who underwent hair implantation for pattern baldness were treated for complications such as infection, foreign-body reaction, pruritus, and scarring. The complications were similar to those reported with synthetic modacrylic fiber implants that have been used for the same purpose. Although we believe this is the first article to report complications from hair implants, the illogical basis of the procedure suggests that complications will occur in many unsuspecting patients who undergo hair implantation. PMID:7009899

  10. Characterisation of irradiation-induced defects in ZnO single crystals

    NASA Astrophysics Data System (ADS)

    Prochazka, I.; Cizek, J.; Lukac, F.; Melikhova, O.; Valenta, J.; Havranek, V.; Anwand, W.; Skuratov, V. A.; Strukova, T. S.

    2016-01-01

    Positron annihilation spectroscopy (PAS) combined with optical methods was employed for characterisation of defects in the hydrothermally grown ZnO single crystals irradiated by 167 MeV Xe26+ ions to fluences ranged from 3×1012 to 1×1014 cm-2. The positron lifetime (LT), Doppler broadening as well as slow-positron implantation spectroscopy (SPIS) techniques were involved. The ab-initio theoretical calculations were utilised for interpretation of LT results. The optical transmission and photoluminescence measurements were conducted, too. The virgin ZnO crystal exhibited a single component LT spectrum with a lifetime of 182 ps which is attributed to saturated positron trapping in Zn vacancies associated with hydrogen atoms unintentionally introduced into the crystal during the crystal growth. The Xe ion irradiated ZnO crystals have shown an additional component with a longer lifetime of ≈ 360 ps which comes from irradiation-induced larger defects equivalent in size to clusters of ≈10 to 12 vacancies. The concentrations of these clusters were estimated on the basis of combined LT and SPIS data. The PAS data were correlated with irradiation induced changes seen in the optical spectroscopy experiments.

  11. Implantable Heart Aid

    NASA Technical Reports Server (NTRS)

    1984-01-01

    CPI's human-implantable automatic implantable defibrillator (AID) is a heart assist system, derived from NASA's space circuitry technology, that can prevent erratic heart action known as arrhythmias. Implanted AID, consisting of microcomputer power source and two electrodes for sensing heart activity, recognizes onset of ventricular fibrillation (VF) and delivers corrective electrical countershock to restore rhythmic heartbeat.

  12. Extraoral Cementation Technique to Minimize Cement-Associated Peri-implant Marginal Bone Loss: Can a Thin Layer of Zinc Oxide Cement Provide Sufficient Retention?

    PubMed

    Frisch, Eberhard; Ratka-Krüger, Petra; Weigl, Paul; Woelber, Johan

    2016-01-01

    This report describes the use of laboratory-fabricated crown intaglio replicas for extraorally prepared cementation of fixed restorations to implants. This technique minimizes excess cement and may therefore reduce the risk of cement-related marginal peri-implant bone loss. It is unclear whether the remaining thin layer of luting agent provides sufficient retention if low-adhesive zinc oxide (ZnO) cement is used. In 85 consecutive patients, 113 single crowns were cemented to implants using extraoral cementation technique (ECT) and ZnO cement. All patients were followed for 6 months and investigated for decementation. Seven events of decementation (incidence: 6.19%) were found in 7 patients (8.24%). ECT may represent a viable cementation technique for implant-supported single crowns, even using low-adhesion cements. PMID:27479343

  13. Diagnosis of arterial prosthetic graft infection by /sup 111/In oxine white blood cell scans

    SciTech Connect

    McKeown, P.P.; Miller, D.C.; Jamieson, S.W.; Mitchell, R.S.; Reitz, B.A.; Olcott, C.; Mehigan, J.T.; Silberstein, R.J.; McDougall, I.R.

    1982-08-01

    Early and accurate diagnosis of infected prosthetic arterial grafts is difficult, despite the application of diverse diagnostic modalities. Delay in making the diagnosis is largely responsible for the high amputation and mortality rates associated with this complication. In nine patients with suspected graft infections, /sup 111/In white blood cell scanning was useful and accurate. Graft infection was proved in five cases and ruled out in three. One false-positive scan was due to a sigmoid diverticular abscess overlying the graft. /sup 111/In white blood cell scans may improve the accuracy of diagnosing infected prosthetic grafts, which may result in better limb and patient salvage rates.

  14. Esthesioneuroblastoma (olfactory neuroblastoma) treated with 111In-octreotide and 177Lu-DOTATATE PRRT.

    PubMed

    Makis, William; McCann, Karey; McEwan, Alexander J B

    2015-04-01

    A 51-year-old man with a recurrent metastatic esthesioneuroblastoma (olfactory neuroblastoma) was referred for peptide receptor radionuclide therapy (PRRT). He received 4 treatments of 111In-octreotide over 8 months and 3 treatments of 177Lu-DOTATATE over 4 months, which helped alleviate his symptoms and improved his quality of life; however, the tumor ultimately progressed and he passed away shortly thereafter. PRRT with 111In-octreotide or 177Lu-DOTATATE could play a role in the management of esthesioneuroblastoma. PMID:25674857

  15. Synthesis and antibacterial properties of ZnO brush pens

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Zhang, Rong; Li, Yilin; Weng, Yuan; Liang, Weiquan; Zhang, Wenfeng; Zheng, Weitao; Hu, Haimei

    2015-12-01

    In this paper, ZnO with a novel hierarchical nanostructure has been synthesized by a new solution method. The novel hierarchical structure is named a ‘brush pen’. The biocompatibility and antibacterial properties of ZnO brush pens have been evaluated. The results demonstrate that ZnO brush pens show good antibacterial activity against Staphylococcus aureus.

  16. Trends in Cochlear Implants

    PubMed Central

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management. PMID:15247993

  17. Intrinsic magnetic order and inhomogeneous transport in Gd-implanted zinc oxide

    NASA Astrophysics Data System (ADS)

    Kennedy, John; Williams, Grant V. M.; Murmu, Peter P.; Ruck, Ben J.

    2013-12-01

    We report the results from magnetic, resistivity, and Hall effect measurements on a ferromagnetically ordered 5% Gd low energy implanted ZnO single crystal. Temperature-dependent magnetization measurements show that the Gd ions do not contribute to the magnetic order; hence, the magnetic order is intrinsic. The electronic transport in the Gd-implanted region is inhomogeneous, and there is a nonlinear Hall resistance. The nonlinear Hall resistance is likely to be a consequence of the inhomogeneous transport and not due to an anomalous Hall effect.

  18. TiO2 nanotube composite layers as delivery system for ZnO and Ag nanoparticles - an unexpected overdose effect decreasing their antibacterial efficacy.

    PubMed

    Roguska, A; Belcarz, A; Pisarek, M; Ginalska, G; Lewandowska, M

    2015-06-01

    Enhancement of biocompatibility and antibacterial properties of implant materials is potentially beneficial for their practical value. Therefore, the use of metallic and metallic oxide nanoparticles as antimicrobial coatings components which induce minimized antibacterial resistance receives currently particular attention. In this work, TiO2 nanotubes layers loaded with ZnO and Ag nanoparticles were designed for biomedical coatings and delivery systems and evaluated for antimicrobial activity. TiO2 nanotubes themselves exhibited considerable and diameter-dependent antibacterial activity against planktonic Staphylococcus epidermidis cells but favored bacterial adhesion. Loading of nanotubes with moderate amount of ZnO nanoparticles significantly diminished S. epidermidis cell adhesion and viability just after 1.5h contact with modified surfaces. However, an increase of loaded ZnO amount unexpectedly altered the structure of nanoparticle-nanolayer, caused partial closure of nanotube interior and significantly reduced ZnO solubility and antibacterial efficacy. Co-deposition of Ag nanoparticles enhanced the antibacterial properties of synthesized coatings. However, the increase of ZnO quantity on Ag nanoparticles co-deposited surfaces favored the adhesion of bacterial cells. Thus, ZnO/Ag/TiO2 nanotube composite layers may be promising delivery systems for combating post-operative infections in hard tissue replacement procedures. However, the amount of loaded antibacterial agents must be carefully balanced to avoid the overdose and reduced efficacy. PMID:25842121

  19. Silicone breast implant materials.

    PubMed

    Daniels, A U

    2012-01-01

    This opinion article has been written on request because of the recent public controversy over silicone breast implants produced by a now-defunct company, Poly Implant Prosthese (PIP) in France. More than 300,000 PIP devices have been implanted. The purposes of my article are to (1.) provide a general overview of silicone breast implant materials, (2.) to describe the general safety of these materials as reported to date, and (3.) to summarise current publicly available information about these aspects of the PIP prostheses. The materials covered are the silicone rubber from which the implant shells are made and the silicone gel used to fill the shell. The materials safety issues are biocompatibility (especially of the gel) and biodurability of the shell. The literature reviewed indicates that biocompatibility is not an issue with other current generation implants. However, biodurability is. A rough estimate of implant shell rupture rate is ~10+% at 10 years. Information is still emerging about the PIP implants. Initial regulatory disclosures suggest the PIP implants may have both biocompatibility and biodurability problems. They also suggest that PIP implants may have been produced using silicone materials not certified as medical grade. Governmental health and regulatory agencies are just now in the process of deciding what actions should be taken to protect patients. PMID:22826101

  20. ZnO nanolasers on graphene films

    NASA Astrophysics Data System (ADS)

    Baek, Hyeonjun; Park, Jun Beom; Park, Jong-woo; Hyun, Jerome K.; Yoon, Hosang; Oh, Hongseok; Yoon, Jiyoung

    2016-06-01

    We grew and characterized zinc oxide (ZnO) nanolasers on graphene films. By using graphene as a growth medium, we were able to prepare position-controlled and vertically aligned ZnO nanotube lasers. The ZnO nanolasers grown on graphene films showed good optical characteristics, evidenced by a low lasing threshold. Furthermore, the nanolaser/graphene system was easily lifted off the original substrate and transferred onto foreign substrates. The lasing performance was observed to be significantly enhanced by depositing a layer of silver on the back of the graphene film during this transfer process, which was quantitatively investigated using finite-difference time-domain simulations. Due to the wide selection of substrates enabled by the use of graphene films, our results suggest promising strategies for preparing practical nanolasers with improved performance.

  1. Dye-Sensitization Of Nanocrystalline ZnO Thin Films

    NASA Astrophysics Data System (ADS)

    Ajimsha, R. S.; Tyagi, M.; Das, A. K.; Misra, P.; Kukreja, L. M.

    2010-12-01

    Nannocrystalline and nanoporus thin films of ZnO were synthesized on glass substrates by using wet chemical drop casting method. X-ray diffraction measurements on these samples confirmed the formation of ZnO nanocrystallites in hexagonal wurtzite phase with mean size of ˜20 nm. Photo sensitization of these nanostructured ZnO thin films was carried out using three types of dyes Rhodamine 6 G, Chlorophyll and cocktail of Rhodamine 6 G and Chlorophyll in 1:1 ratio. Dye sensitized ZnO thin films showed enhanced optical absorption in visible spectral region compared to the pristine ZnO thin films.

  2. Dye-Sensitization Of Nanocrystalline ZnO Thin Films

    SciTech Connect

    Ajimsha, R. S.; Tyagi, M.; Das, A. K.; Misra, P.; Kukreja, L. M.

    2010-12-01

    Nannocrystalline and nanoporus thin films of ZnO were synthesized on glass substrates by using wet chemical drop casting method. X-ray diffraction measurements on these samples confirmed the formation of ZnO nanocrystallites in hexagonal wurtzite phase with mean size of {approx}20 nm. Photo sensitization of these nanostructured ZnO thin films was carried out using three types of dyes Rhodamine 6 G, Chlorophyll and cocktail of Rhodamine 6 G and Chlorophyll in 1:1 ratio. Dye sensitized ZnO thin films showed enhanced optical absorption in visible spectral region compared to the pristine ZnO thin films.

  3. Tailoring the coercivity in ferromagnetic ZnO thin films by 3d and 4f elements codoping

    SciTech Connect

    Lee, J. J.; Xing, G. Z. Yi, J. B.; Li, S.; Chen, T.; Ionescu, M.

    2014-01-06

    Cluster free, Co (3d) and Eu (4f) doped ZnO thin films were prepared using ion implantation technique accompanied by post annealing treatments. Compared with the mono-doped ZnO thin films, the samples codoped with Co and Eu exhibit a stronger magnetization with a giant coercivity of 1200 Oe at ambient temperature. This was further verified through x-ray magnetic circular dichroism analysis, revealing the exchange interaction between the Co 3d electrons and the localized carriers induced by Eu{sup 3+} ions codoping. The insight gained with modulating coercivity in magnetic oxides opens up an avenue for applications requiring non-volatility in spintronic devices.

  4. Quantitative simultaneous 111In/99mTc SPECT-CT of osteomyelitis

    PubMed Central

    Cervo, Morgan; Gerbaudo, Victor H.; Park, Mi-Ae; Moore, Stephen C.

    2013-01-01

    Purpose: A well-established approach for diagnostic imaging of osteomyelitis (OM), a bone infection, is simultaneous SPECT-CT of 99mTc sulfur colloid (SC) and 111In white blood cells (WBC). This method provides essentially perfect spatial registration of the tracers within anatomic sites of interest. Currently, diagnosis is based purely on a visual assessment—where relative discordance between 99mTc and 111In uptake in bone, i.e., high 111In and low 99mTc, suggests OM. To achieve more quantitative images, noise, scatter, and crosstalk between radionuclides must be addressed through reconstruction. Here the authors compare their Monte Carlo-based joint OSEM (MC-JOSEM) algorithm, which reconstructs both radionuclides simultaneously, to a more conventional triple-energy window-based reconstruction (TEW-OSEM), and to iterative reconstruction with no compensation for scatter (NC-OSEM). Methods: The authors created numerical phantoms of the foot and torso. Multiple bone-infection sites were modeled using high-count Monte Carlo simulation. Counts per voxel were then scaled to values appropriate for 111In WBC and 99mTc SC imaging. Ten independent noisy projection image sets were generated by drawing random Poisson deviates from these very low-noise images. Data were reconstructed using the two iterative scatter-compensation methods, TEW-OSEM and MC-JOSEM, as well as the uncorrected method (NC-OSEM). Mean counts in volumes of interest (VOIs) were used to evaluate the bias and precision of each method. Data were also acquired using a phantom, approximately the size of an adult ankle, consisting of regions representing infected and normal bone marrow, within a bone-like attenuator and surrounding soft tissue; each compartment contained a mixture of 111In and 99mTc. Low-noise data were acquired during multiple short scans over 29 h on a Siemens Symbia T6 SPECT-CT with medium-energy collimators. Pure 99mTc and 111In projection datasets were derived by fitting the acquired

  5. Controlled doping of graphene using ZnO substrates

    NASA Astrophysics Data System (ADS)

    Si, Misuk; Choi, Won Jin; Jeong, Yoon Jang; Lee, Young Kuk; Kim, Ju-Jin; Lee, Jeong-O.

    2016-06-01

    We show that graphene device could be controllably doped by the bottom substrate by inserting atomic layer deposition grown ZnO between graphene and SiO2 substrate. To clarify the effect of bottom ZnO, length of the graphene transistor channel was varied from 20 to 200 μm, while that of ZnO was fixed to 10 μm. Graphene devices supported on ZnO film show marked difference from those supported on SiO2 substrates; bottom ZnO layer behave as an electron donor. UV illumination experiment on hybrid graphene-ZnO device reveals that the effect of doping from ZnO becomes negligible when the graphene channel length made about four times larger than that of ZnO stripe.

  6. Characterization of reaction between ZnO and COS

    SciTech Connect

    Sasaoka, Eiji; Taniguchi, Kazuo; Uddin, M.A.; Hirano, Shigeru; Kasaoka, Shigeaki; Sakata, Yusaku

    1996-07-01

    In order to understand the behavior of COS in a ZnO desulfurization reactor, the reaction between ZnO and COS was studied in the presence of gases which compose a coal-derived gas. The behavior of COS in the reaction zone of a ZnO packed bed can be predicted as follows: H{sub 2}S in coal-derived gas reacts more easily with ZnO than COS; most of COS is converted to H{sub 2}S by catalytic hydrolysis and then reacts with ZnO, although a part of COS may react directly with ZnO; H{sub 2} accelerates the conversion of COS to H{sub 2}S; the water-gas shift reaction accelerates the reaction between ZnO and COS; and CO{sub 2} does not affect the reaction.

  7. Antibacterial and Antifungal Activity of ZnO Containing Glasses.

    PubMed

    Esteban-Tejeda, Leticia; Prado, Catuxa; Cabal, Belén; Sanz, Jesús; Torrecillas, Ramón; Moya, José Serafín

    2015-01-01

    A new family of non-toxic biocides based on low melting point (1250°C) transparent glasses with high content of ZnO (15-40wt%) belonging to the miscibility region of the B2O3-SiO2-Na2O-ZnO system has been developed. These glasses have shown an excellent biocide activity (logarithmic reduction >3) against Gram- (E. coli), Gram+ (S. aureus) and yeast (C. krusei); they are chemically stable in different media (distilled water, sea-like water, LB and DMEN media) as well as biocompatible. The cytotoxicity was evaluated by the Neutral Red Uptake using NIH-3T3 (mouse embryonic fibroblast cells) and the cell viability was >80%. These new glasses can be considered in several and important applications in the field of inorganic non-toxic biocide agents such as medical implants, surgical equipment, protective apparels in hospitals, water purifications systems, food packaging, food storages or textiles. PMID:26230940

  8. Antibacterial and Antifungal Activity of ZnO Containing Glasses

    PubMed Central

    Esteban-Tejeda, Leticia; Prado, Catuxa; Cabal, Belén; Sanz, Jesús; Torrecillas, Ramón; Moya, José Serafín

    2015-01-01

    A new family of non-toxic biocides based on low melting point (1250°C) transparent glasses with high content of ZnO (15–40wt%) belonging to the miscibility region of the B2O3-SiO2-Na2O-ZnO system has been developed. These glasses have shown an excellent biocide activity (logarithmic reduction >3) against Gram- (E. coli), Gram+ (S. aureus) and yeast (C. krusei); they are chemically stable in different media (distilled water, sea-like water, LB and DMEN media) as well as biocompatible. The cytotoxicity was evaluated by the Neutral Red Uptake using NIH-3T3 (mouse embryonic fibroblast cells) and the cell viability was >80%. These new glasses can be considered in several and important applications in the field of inorganic non-toxic biocide agents such as medical implants, surgical equipment, protective apparels in hospitals, water purifications systems, food packaging, food storages or textiles. PMID:26230940

  9. Larynx: implants and stents

    PubMed Central

    Sittel, Christian

    2011-01-01

    In the human larynx, implants a primarily used for the correction of glottis insufficiency. In a broader sense laryngeal stents may be considered as implants as well. Laryngeal implants can be differentiated into injectable and solid. The most important representatives of both groups are discussed in detail along with the respective technique of application. Laryngeal stents are primarily used perioperatively. Different types and their use are presented. PMID:22073097

  10. Implants in adolescents

    PubMed Central

    Shah, Rohit A.; Mitra, Dipika K.; Rodrigues, Silvia V.; Pathare, Pragalbha N.; Podar, Rajesh S.; Vijayakar, Harshad N.

    2013-01-01

    Implants have gained tremendous popularity as a treatment modality for replacement of missing teeth in adults. There is extensive research present on the use of implants in adults, but there is a dearth of data available on the same in adolescents. The treatment planning and execution of implant placement in adolescents is still in its infancy. This review article is an attempt to bring together available literature. PMID:24174743

  11. Evaluation of [111In]-Labeled Zinc-Dipicolylamine Tracers for SPECT Imaging of Bacterial Infection

    PubMed Central

    Rice, Douglas R.; Plaunt, Adam J.; Turkyilmaz, Serhan; Smith, Miles; Wang, Yuzhen; Rusckowski, Mary

    2015-01-01

    Purpose This study prepared three structurally related zinc-dipicolylamine (ZnDPA) tracers with [111In] labels and conducted biodistribution and SPECT/CT imaging studies of a mouse leg infection model. Methods Two monovalent tracers, ZnDPA-[111In]DTPA and ZnDPA-[111In]DOTA, each with a single zinc-dipicolylamine targeting unit, and a divalent tracer, Bis(ZnDPA)-[111In]DTPA,with two zinc-dipicolylamine units were prepared. Organ biodistribution and SPECT/CT imaging studies were performed on living mice with a leg infection created by injection of clinically relevant Gram positive Streptococcus pyogenes. Fluorescent and luminescent Eu3+-labeled versions of these tracers were also prepared and used to measure relative affinity for the exterior membrane surface of bacterial cells and mimics of healthy mammalian cells. Results All three 111In-labeled radiotracers were prepared with radiopurity > 90%. The biodistribution studies showed that the two monovalent tracers were cleared from the body through the liver and kidney, with retained % injected dose for all organs of < 8 % at 20 hours and infected leg T/NT ratio of ≤ 3.0. Clearance of the divalent tracer from the bloodstream was slower and primarily through the liver, with a retained % injected dose for all organs < 37% at 20 hours and T/NT ratio rising to 6.2 after 20 hours. The SPECT/CT imaging indicated the same large difference in tracer pharmacokinetics and higher accumulation of the divalent tracer at the site of infection. Conclusions All three [111In]-ZnDPA tracers selectively targeted the site of a clinically relevant mouse infection model that could not be discerned by visual external inspection of the living animal. The highest target selectivity, observed with a divalent tracer equipped with two zinc-dipicolylamine targeting units, compares quite favorably with the imaging selectivities previously reported for other nuclear tracers that target bacterial cell surfaces. The tracer pharmacokinetics depended

  12. Gold bead implants.

    PubMed

    Durkes, T E

    1992-03-01

    Gold bead implantation is an experimental area of study in the acupuncture field dealing with chronic diseases. Special acupuncture techniques are required to implant the gold beads successfully in the proper location. Gold beads are used to treat degenerative joint disease, osteochondritis, osteochondritis dessicans, ventral spondylosis, and seizures. PMID:1581658

  13. Implantable, Ingestible Electronic Thermometer

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard

    1987-01-01

    Small quartz-crystal-controlled oscillator swallowed or surgically implanted provides continuous monitoring of patient's internal temperature. Receiver placed near patient measures oscillator frequency, and temperature inferred from previously determined variation of frequency with temperature. Frequency of crystal-controlled oscillator varies with temperature. Circuit made very small and implanted or ingested to measure internal body temperature.

  14. Synthetic facial implants.

    PubMed

    Quatela, Vito C; Chow, Jen

    2008-02-01

    This article presents a range of synthetic implant materials for use in facial plastic surgery. The authors discuss alternatives to autogenous tissue transfer in terms of biocompatibility, technique, complications, controversies, and cautions. The reader is presented information about a range of synthetic implant materials such as silicone, polyester fiber, polyamide mesh, metal, polyethylene, polyacrylamide gel, hydroxyapatite, polylactic acid, collagen, and others. PMID:18063244

  15. Smoking and dental implants

    PubMed Central

    Kasat, V.; Ladda, R.

    2012-01-01

    Smoking is a prevalent behaviour in the population. The aim of this review is to bring to light the effects of smoking on dental implants. These facts will assist dental professionals when implants are planned in tobacco users. A search of “PubMed” was made with the key words “dental implant,” “nicotine,” “smoking,” “tobacco,” and “osseointegration.” Also, publications on tobacco control by the Government of India were considered. For review, only those articles published from 1988 onward in English language were selected. Smoking has its influence on general as well as oral health of an individual. Tobacco negatively affects the outcome of almost all therapeutic procedures performed in the oral cavity. The failure rate of implant osseointegration is considerably higher among smokers, and maintenance of oral hygiene around the implants and the risk of peri-implantitis are adversely affected by smoking. To increase implant survival in smokers, various protocols have been recommended. Although osseointegrated dental implants have become the state of the art for tooth replacement, they are not without limitations or complications. In this litigious era, it is extremely important that the practitioner clearly understands and is able and willing to convey the spectrum of possible complications and their frequency to the patients. PMID:24478965

  16. Batteryless implanted echosonometer

    NASA Technical Reports Server (NTRS)

    Kojima, G. K.

    1977-01-01

    Miniature ultrasonic echosonometer implanted within laboratory animals obtains energy from RF power oscillator that is electronically transduced via induction loop to power receiving loop located just under animal's skin. Method of powering device offers significant advantages over those in which battery is part of implanted package.

  17. Implantable CMOS Biomedical Devices

    PubMed Central

    Ohta, Jun; Tokuda, Takashi; Sasagawa, Kiyotaka; Noda, Toshihiko

    2009-01-01

    The results of recent research on our implantable CMOS biomedical devices are reviewed. Topics include retinal prosthesis devices and deep-brain implantation devices for small animals. Fundamental device structures and characteristics as well as in vivo experiments are presented. PMID:22291554

  18. Percutaneous and skeletal biocarbon implants

    NASA Technical Reports Server (NTRS)

    Mooney, V.

    1977-01-01

    Review of carbon implants developed by NASA discussed four different types of implants and subsequent improvements. Improvements could be of specific interest to rehabilitation centers and similar organizations.

  19. Number of implants for mandibular implant overdentures: a systematic review

    PubMed Central

    Lee, Jeong-Yol; Kim, Ha-Young; Bryant, S. Ross

    2012-01-01

    PURPOSE The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants. PMID:23236572

  20. Graphene for Biomedical Implants

    NASA Astrophysics Data System (ADS)

    Moore, Thomas; Podila, Ramakrishna; Alexis, Frank; Rao, Apparao; Clemson Bioengineering Team; Clemson Physics Team

    2013-03-01

    In this study, we used graphene, a one-atom thick sheet of carbon atoms, to modify the surfaces of existing implant materials to enhance both bio- and hemo-compatibility. This novel effort meets all functional criteria for a biomedical implant coating as it is chemically inert, atomically smooth and highly durable, with the potential for greatly enhancing the effectiveness of such implants. Specifically, graphene coatings on nitinol, a widely used implant and stent material, showed that graphene coated nitinol (Gr-NiTi) supports excellent smooth muscle and endothelial cell growth leading to better cell proliferation. We further determined that the serum albumin adsorption on Gr-NiTi is greater than that of fibrinogen, an important and well understood criterion for promoting a lower thrombosis rate. These hemo-and biocompatible properties and associated charge transfer mechanisms, along with high strength, chemical inertness and durability give graphene an edge over most antithrombogenic coatings for biomedical implants and devices.

  1. [Implantable medical devices].

    PubMed

    Crickx, B; Arrault, X

    2008-01-01

    Medical devices have been individualized to include a category of implantable medical devices, "designed to be totally implanted in the human body or to replace an epithelial surface or a surface of the eye, through surgery, and remain in place after the intervention" (directive 93/42/CEE and decree of 20 April 206). Each implantable medical device has a common name and a commercial name for precise identification of the model (type/references). The users' service and the implanting physician should be clearly identified. There are a number of rules concerning health traceability to rapidly identify patients exposed to risks in which the implantable medical devices of a particular batch or series were used and to monitor the consequences. The traceability data should be preserved 10 years and the patient's medical file for 20 years. PMID:18442666

  2. Cochlear implants in children.

    PubMed

    Young, N M

    1994-04-01

    Children with such profound deafness that they are not helped by hearing aids are now candidates for cochlear implantation. This technology permits us to provide these children with a significant degree of useful hearing. The degree of improvement in speech perception and spoken language in pediatric cochlear implant recipients varies. However, the younger the children and the less time they have been completely deprived of auditory stimuli, the more likely they are to make significant progress. The evaluation of the deaf child for implantation is best done by a multidisciplinary team who understands the needs of hearing-impaired children and who can work with the family, the child, and classroom teachers, as well as other school professionals. The decision to proceed with cochlear implantation in a child is one that requires long-term commitment on the part of the family and the cochlear implant team. PMID:8039409

  3. Pediatric leptomeningeal metastasis: 111In-DTPA cerebrospinal fluid flow studies.

    PubMed

    Chamberlain, M C

    1994-04-01

    Nine children (five girls and four boys) ranging in age from 1 to 18 years (median age, 12 years) with leptomeningeal metastasis were evaluated for cerebrospinal fluid compartmentalization with cerebrospinal fluid flow studies using ventricular diethylenetriaminepentaacetic acid labeled with indium 111 (111In-DTPA). Histologic diagnosis included medulloblastoma (two), primitive neuroectodermal tumor (two), acute lymphoblastic leukemia (two), pineoblastoma (one), ependymoma (one), and anaplastic astrocytoma (one). Sixteen 111In-DTPA cerebrospinal fluid flow studies were performed, of which nine demonstrated normal anterograde cerebrospinal fluid flow of radionuclide, with the following cerebrospinal fluid compartment median times to appearance, with ranges in parentheses: ventricles, 1 minute (0 to 3 minutes); cisterna magna/basal cisterns, 5 minutes (3 to 5 minutes); cervical subarachnoid space, 8 minutes (5 to 10 minutes); thoracic subarachnoid space, 15 minutes (10 to 30 minutes); lumbar subarachnoid space, 35 minutes (20 to 45 minutes); and sylvian cistern, 80 minutes (60 to 90 minutes). Blockage of normal anterograde cerebrospinal fluid flow was seen in seven 111In-DTPA cerebrospinal fluid flow studies in the following cerebrospinal fluid compartments: cervical subarachnoid space (four), lumbar subarachnoid space (two), and cisterna magna/basal cisterns (one). Five 111In-DTPA cerebrospinal fluid flow studies were performed after demonstration of cerebrospinal fluid compartmentalization and treatment with limited-field radiation therapy to involved regions; cerebrospinal fluid flow blocks resolved in three. In conclusion, cerebrospinal fluid compartmentalization, as shown by radionuclide ventriculography, is a common occurrence in pediatric leptomeningeal metastasis (four of nine patients, or 44%) and may be palliated by involved-field radiotherapy. PMID:8006365

  4. Radioimmunodetection in rhabdo- and leiomyosarcoma with sup 111 In-anti-myosin monoclonal antibody complex

    SciTech Connect

    Planting, A.; Verweij, J.; Cox, P.; Pillay, M.; Stoter, G. )

    1990-02-01

    In patients with rhabdo- and leiomyosarcoma a radioimmunodiagnostic study was performed with {sup 111}In labeled F(ab) fragments of a monoclonal antibody against myosin. Eight patients with rhabdomyosarcoma and 18 patients with leiomyosarcoma were studied. Scanning was performed at 4, 24, and 48 h after administration of 74 MBeq of the antibody complex. A high uptake with a tumor:background ratio of 10:1 was observed in several patients with rhabdomyosarcoma but the results were less accurate in leiomyosarcoma.

  5. Clinical diagnostic application of 111In-DTPA-octreotide scintigraphy in small cell lung cancer.

    PubMed

    Vaccarili, M; Lococo, A; Fabiani, F; Staffilano, A

    2000-01-01

    Some years ago it was proved that a good percentage of small cell lung cancers, classified among cancers of the APUD system, produces somatostatin receptors that can be detected in vivo by scintigraphy with 111In-DTPA-octreotide. With the method in the whole body it is possible to identify the principal neoformation and the probable metastases. The authors present a study of 21 patients afflicted with small cell lung cancer diagnosed histologically. The study, carried out between January 1995 and December 1997, compared the radiologic iconography of the CT scan with the scintigraphic map obtained by a planar scintigraphy and in SPECT 1, 4 and 24-hr after iv injection of 110 MBq of 111In-DTPA-octreotide. The comparison was made with reference to the principal neoplasm and probable metastases. A scintigraphic study, a CT of restaging and a follow-up, done after 3 and 6 months of chemotherapy, on 15 patients with cancer that produces somatostatin receptors proved that the neoplasm sometimes regresses and sometimes progresses. In the latter case, it is possible to identify cerebral, mediastinal and hepatic metastases with the administration of 200 microg of octreotide 3 times a day for 7 days before the scintigraphy. In fact, the administration lowers background activity. The authors concluded that scintigraphy with 111In-DTPA-octreotide plays an important part in the study of patients afflicted with small cell lung cancer. Scintigraphy identifies the subgroups of patients who can be cured with somatostatin analogues together with chemotherapy. Scintigraphy presents a good sensibility in the re-staging and in the follow-up of patients who are treated, even though it is difficult to identify subdiaphragmatic metastases where liver, spleen and kidney show an increase in 111In-DTPA-octreotide. PMID:10939603

  6. Growth of vertically aligned one-dimensional ZnO nanowire arrays on sol-gel derived ZnO thin films

    NASA Astrophysics Data System (ADS)

    Kitazawa, Nobuaki; Aono, Masami; Watanabe, Yoshihisa

    2014-11-01

    Vertically aligned one-dimensional ZnO nanowire arrays have been synthesized by a hydrothermal method on sol-gel derived ZnO films. Sol-gel derived ZnO films and corresponding ZnO nanowire arrays have been characterized by X-ray diffraction and field-emission scanning electron microscopy. The effect of sol-gel derived ZnO film surface on the morphology of ZnO nanowire arrays has been investigated. The authors suggest from our investigation that sol-gel derived ZnO films affect the growth of one-dimensional ZnO nanostructures. Not only crystalline ZnO films but also amorphous ones can act as a scaffold for ZnO nucleus. Tilted ZnO micro-rods are grown on ZnO gel films, whereas vertically aligned ZnO nanowire arrays are grown on nanometer-sized ZnO grains. The average diameter of ZnO nanowire arrays are correlated strongly with the grain size of sol-gel derived ZnO films.

  7. Evaluation of the viability of /sup 111/In-abeled DTPA coupled to fibrinogen

    SciTech Connect

    Layne, W.W.; Hnatowich, D.J.; Doherty, P.W.; Childs, R.L.; Lanteigne, D.; Ansell, J.

    1982-07-01

    In earlier work, DTPA has been covalently coupled to albumin via the cyclic anhydride of DTPA. Using fibrinogen, we have studied the effect of such coupling on protein viability by both an in vitro and an in vivo assay. Clotting time remained identical to that of the native protein whether the anhydride-to-protein molar ratio was 1:1 or 5:1. In vivo studies were done in dogs, with human fibrinogen labeled with /sup 125/I and /sup 111/In. Throughout 130 hr, blood clearances for the two tracers agreed whether with 1:1 or 5:1 coupling. In a dog model with a thrombogenic catheter, the clot-to-blood ratios for the two radiotracers agreed within experimental error. Finally, 1:1-coupled canine fibrinogen, labeled with /sup 111/In, was administered to dogs with a catheter in a jugular vein, and scintigrams at 24 hr clearly showed clotting along the length of the catheter. We conclude that fibrinogen, coupled to DTPA, retains its viability, behaving like radioiodinated fibrinogen in vivo, and /sup 111/In labeled fibrinogen looks promising as a clinical diagnostic agent.

  8. Evaluation of 111In-labeled Anginex as Potential SPECT Tracer for Imaging of Tumor Angiogenesis.

    PubMed

    Van Mourik, Tiemen R; Läppchen, Tilman; Rossin, Raffaella; Van Beijnum, Judy R; Macdonald, John R; Mayo, Kevin H; Griffioen, Arjan W; Nicolay, Klaas; Grüll, Holger

    2015-11-01

    Angiogenesis is a prerequisite for solid tumors to grow and metastasize, providing oxygen and nutrients to the tumor site. The protein galectin-1 has been identified to be overexpressed on tumor vasculature and represents an interesting target for anti-angiogenic therapy, as well as in molecular imaging. Therefore, the galectin-1-binding peptide Anginex was modified for radiolabeling using (111)In. In vitro, (111)In-Ax showed significantly more binding to galectin-1-positive EC-RF24 and MDA-MB-231-LITG cells than to galectin-1-negative LS174T cells and association with EC-RF24 cells was reduced in the presence of excess native Anginex. However, ex vivo biodistribution profiles showed little tumor uptake of (111)In-Ax and extensive accumulation in non-target organs. Although this study shows the ease of modification of the therapeutic peptide Anginex and favorable characteristics in vitro, in vivo assessment of the tracer revealed negligible tumor targeting. Hence, the strategy we employed lends little support for successful non-invasive imaging of tumor angiogenesis using this peptide. PMID:26504018

  9. Synthesis and characterization of ZnO thin films

    NASA Astrophysics Data System (ADS)

    Anilkumar T., S.; Girija M., L.; Venkatesh, J.

    2016-05-01

    Zinc oxide (ZnO) Thin films were deposited on glass substrate using Spin coating method. Zinc acetate dehydrate, Carbinol and Mono-ethanolamine were used as the precursor, solvent and stabilizer respectively to prepare ZnO Thin-films. The molar ratio of Monoethanolamine to Zinc acetate was maintained as approximately 1. The thickness of the films was determined by Interference technique. The optical properties of the films were studied by UV Vis-Spectrophotometer. From transmittance and absorbance curve, the energy band gap of ZnO is found out. Electrical Conductivity measurements of ZnO are carried out by two probe method and Activation energy for the electrical conductivity of ZnO are found out. The crystal structure and orientation of the films were analyzed by XRD. The XRD patterns show that the ZnO films are polycrystalline with wurtzite hexagonal structure.

  10. Physical vapor transport crystal growth of ZnO

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Jianping, Ma; Fuli, Liu; Yuan, Zang; Yantao, Liu

    2014-03-01

    Zinc oxide (ZnO) has a wide band gap, high stability and a high thermal operating range that makes it a suitable material as a semiconductor for fabricating light emitting diodes (LEDs) and laser diodes, photodiodes, power diodes and other semiconductor devices. Recently, a new crystal growth for producing ZnO crystal boules was developed, which was physical vapor transport (PVT), at temperatures exceeding 1500 °C under a certain system pressure. ZnO crystal wafers in sizes up to 50 mm in diameter were produced. The conditions of ZnO crystal growth, growth rate and the quality of ZnO crystal were analyzed. Results from crystal growth and material characterization are presented and discussed. Our research results suggest that the novel crystal growth technique is a viable production technique for producing ZnO crystals and substrates for semiconductor device applications.

  11. Homoepitaxial regrowth habits of ZnO nanowire arrays

    PubMed Central

    2011-01-01

    Synthetic regrowth of ZnO nanowires [NWs] under a similar chemical vapor transport and condensation [CVTC] process can produce abundant ZnO nanostructures which are not possible by a single CVTC step. In this work, we report three different regrowth modes of ZnO NWs: axial growth, radial growth, and both directions. The different growth modes seem to be determined by the properties of initial ZnO NW templates. By varying the growth parameters in the first-step CVTC process, ZnO nanostructures (e.g., nanoantenna) with drastically different morphologies can be obtained with distinct photoluminescence properties. The results have implications in guiding the rational synthesis of various ZnO NW heterostructures. PMID:22151820

  12. Dental Implant Systems

    PubMed Central

    Oshida, Yoshiki; Tuna, Elif B.; Aktören, Oya; Gençay, Koray

    2010-01-01

    Among various dental materials and their successful applications, a dental implant is a good example of the integrated system of science and technology involved in multiple disciplines including surface chemistry and physics, biomechanics, from macro-scale to nano-scale manufacturing technologies and surface engineering. As many other dental materials and devices, there are crucial requirements taken upon on dental implants systems, since surface of dental implants is directly in contact with vital hard/soft tissue and is subjected to chemical as well as mechanical bio-environments. Such requirements should, at least, include biological compatibility, mechanical compatibility, and morphological compatibility to surrounding vital tissues. In this review, based on carefully selected about 500 published articles, these requirements plus MRI compatibility are firstly reviewed, followed by surface texturing methods in details. Normally dental implants are placed to lost tooth/teeth location(s) in adult patients whose skeleton and bony growth have already completed. However, there are some controversial issues for placing dental implants in growing patients. This point has been, in most of dental articles, overlooked. This review, therefore, throws a deliberate sight on this point. Concluding this review, we are proposing a novel implant system that integrates materials science and up-dated surface technology to improve dental implant systems exhibiting bio- and mechano-functionalities. PMID:20480036

  13. Optimizing stem cell functions and antibacterial properties of TiO2 nanotubes incorporated with ZnO nanoparticles: experiments and modeling

    PubMed Central

    Liu, Wenwen; Su, Penglei; Gonzales, Arthur; Chen, Su; Wang, Na; Wang, Jinshu; Li, Hongyi; Zhang, Zhenting; Webster, Thomas J

    2015-01-01

    To optimize mesenchymal stem cell differentiation and antibacterial properties of titanium (Ti), nano-sized zinc oxide (ZnO) particles with tunable concentrations were incorporated into TiO2 nanotubes (TNTs) using a facile hydrothermal strategy. It is revealed here for the first time that the TNTs incorporated with ZnO nanoparticles exhibited better biocompatibility compared with pure Ti samples (controls) and that the amount of ZnO (tailored by the concentration of Zn(NO3)2 in the precursor) introduced into TNTs played a crucial role on their osteogenic properties. Not only was the alkaline phosphatase activity improved to about 13.8 U/g protein, but the osterix, collagen-I, and osteocalcin gene expressions was improved from mesenchymal stem cells compared to controls. To further explore the mechanism of TNTs decorated with ZnO on cell functions, a response surface mathematical model was used to optimize the concentration of ZnO incorporation into the Ti nanotubes for stem cell differentiation and antibacterial properties for the first time. Both experimental and modeling results confirmed (R2 values of 0.8873–0.9138 and 0.9596–0.9941, respectively) that Ti incorporated with appropriate concentrations (with an initial concentration of Zn(NO3)2 at 0.015 M) of ZnO can provide exceptional osteogenic properties for stem cell differentiation in bone cells with strong antibacterial effects, properties important for improving dental and orthopedic implant efficacy. PMID:25792833

  14. Photophysics and photochemistry of quantized ZnO colloids

    SciTech Connect

    Kamat, P.V.; Patrick, B.

    1992-08-06

    The photophysical and photochemical behavior of quantized ZnO colloids in ethanol has been investigated by time-resolved transient absorption and emission measurements. Trapping of electrons at the ZnO surface resulted in broad absorption in the red region. The green emission of ZnO colloids was readily quenched by hole scavengers such as SCN{sup -} and I{sup -}. The photoinduced charge transfer to these hole scavengers was studied by laser flash photolysis. The yield of oxidized product increased considerably when ZnO colloids were coupled with ZnSe. 36 refs., 11 figs., 1 tab.

  15. Substrate Preparations in Epitaxial ZnO Film Growth

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, C.-H.; Lehoczky, S. L.; Harris, M. T.; Callahan, M. J.; George, M. A.

    2000-01-01

    Epitaxial ZnO films were grown on the two polar surfaces (O-face and Zn-face) of (0001) ZnO single crystal substrates using off-axis magnetron sputtering deposition. Annealing-temperature dependence of ZnO substrates was studied. ZnO films grown on sapphire substrates have also been investigated for comparison purposes and the annealing temperature of A1203 substrates is 1000 C. Substrates and films were characterized using photoluminescence (PL) spectrum, x-ray diffraction, atomic force microscope, energy dispersive spectrum, and electric transport measurements. It has been found that the ZnO film properties were different when films were grown on the two polarity surfaces of ZnO substrates and the A1203 substrates. An interesting result shows that high temperature annealing of ZnO single crystals will improve the surface structure on the O-face surface rather than the opposite surface. The measurements of homoepitaxial ZnO films indicate that the O-terminated surface is better for ZnO epitaxial film growth.

  16. Buffer layer effect on ZnO nanorods growth alignment

    NASA Astrophysics Data System (ADS)

    Zhao, Dongxu; Andreazza, Caroline; Andreazza, Pascal; Ma, Jiangang; Liu, Yichun; Shen, Dezhen

    2005-06-01

    Vertical aligned ZnO nanorods array was fabricated on Si with introducing a ZnO thin film as a buffer layer. Two different nucleation mechanisms were found in growth process. With using Au catalyst, Zn vapor could diffuse into Au nanoclusters with forming a solid solution. Then the ZnO nucleation site is mainly on the catalyst by oxidation of Au/Zn alloy. Without catalyst, nucleation could occur directly on the surface of buffer layer by homoepitaxy. The density and the size of ZnO nanorods could be governed by morphological character of catalyst and buffer layer. The nanorods growth is followed by vapor-solid mechanism.

  17. [Implantable hearing aids].

    PubMed

    Luers, J C; Beutner, D; Hüttenbrink, K-B

    2011-10-01

    Strictly speaking, implantable hearing aids are technical systems that process audiological signals and convey these by direct mechanical stimulation of the ossicular chain or cochlea. They have certain benefits over conventional hearing aids in terms of wearing comfort and general acceptance. As current studies lack convincing audiological results, the indications for implantable hearing aids are primarily of medical or cosmetic nature. To date, three systems are available in Germany: Vibrant Soundbridge®, Carina®, and Esteem®. Because the performance of the different implantable and nonimplantable hearing systems together with various surgical procedures are currently undergoing major changes, audiological indications may also develop in the future. PMID:21956678

  18. Reflections on Rodent Implantation.

    PubMed

    Cha, Jeeyeon M; Dey, Sudhansu K

    2015-01-01

    Embryo implantation is a complex process involving endocrine, paracrine, autocrine, and juxtacrine modulators that span cell-cell and cell-matrix interactions. The quality of implantation is predictive for pregnancy success. Earlier observational studies formed the basis for genetic and molecular approaches that ensued with emerging technological advances. However, the precise sequence and details of the molecular interactions involved have yet to be defined. This review reflects briefly on aspects of our current understanding of rodent implantation as a tribute to Roger Short's lifelong contributions to the field of reproductive physiology. PMID:26450495

  19. Transcatheter aortic valve implantation

    PubMed Central

    Oliemy, Ahmed

    2014-01-01

    Transcatheter aortic valve implantation was developed to offer a therapeutic solution to patients with severe symptomatic aortic stenosis who are not candidates for conventional aortic valve replacement. The improvement in transcatheter aortic valve implantation outcomes is still of concern in the areas of stroke, vascular injury, heart block, paravalvular regurgitation and valve durability. Concomitantly, the progress, both technical and in terms of material advances of transcatheter valve systems, as well as in patient selection, renders transcatheter aortic valve implantation an increasingly viable treatment for more and more patients with structural heart disease. PMID:25374670

  20. Radiolabeling of equine platelets in plasma with /sup 111/In-(2-mercaptopyridine-N-oxide) and their in vivo survival

    SciTech Connect

    Coyne, C.P.; Kelly, A.B.; Hornof, W.J.; O'Brien, T.R.; Philp, M.S.; Lamb, J.F.

    1987-03-01

    A method is presented for the in vitro isolation and radiolabeling of equine platelets with the isotope indium /sup 111/ (/sup 111/In: half-life = 2.8 days, gamma = 173 keV, 89%; 247 keV, 94%). The technique described involves complexing /sup 111/In with the lipid-soluble chelating agent, 2-mercaptopyridine-N-oxide (merc), in an aqueous medium. /sup 111/In-merc platelet-labeling efficiencies in autologous plasma pretreated with or without ferric citrate reagent were 82 +/- 7% and 24 +/- 12%, respectively. Mean intravascular survivals of /sup 111/In-merc-radiolabeled platelets in 8 healthy horses according to simple linear, exponential, mean, weighted-mean residual sum of squares analysis, and multiple-hit model were 5.5 +/- 0.49, 3.5 +/- 0.53, 4.5 +/- 0.18, 4.3 +/- 0.65, and 3.6 +/- 0.97 days, respectively.

  1. The evolution of embryo implantation.

    PubMed

    McGowen, Michael R; Erez, Offer; Romero, Roberto; Wildman, Derek E

    2014-01-01

    Embryo implantation varies widely in placental mammals. We review this variation in mammals with a special focus on two features: the depth of implantation and embryonic diapause. We discuss the two major types of implantation depth, superficial and interstitial, and map this character on a well-resolved molecular phylogenetic tree of placental mammals. We infer that relatively deep interstitial implantation has independently evolved at least eight times within placental mammals. Moreover, the superficial type of implantation represents the ancestral state for placental mammals. In addition, we review the genes involved in various phases of implantation, and suggest a future direction in investigating the molecular evolution of implantation-related genes. PMID:25023681

  2. Sodium doping in ZnO crystals

    SciTech Connect

    Parmar, N. S. Lynn, K. G.

    2015-01-12

    ZnO bulk single crystals were doped with sodium by thermal diffusion. Positron annihilations spectroscopy confirms the filling of zinc vacancies, to >6 μm deep in the bulk. Secondary-ion mass spectrometry measurement shows the diffusion of sodium up to 8 μm with concentration (1–3.5) × 10{sup 17 }cm{sup −3}. Broad photoluminescence excitation peak at 3.1 eV, with onset appearance at 3.15 eV in Na:ZnO, is attributed to an electronic transition from a Na{sub Zn} level at ∼(220–270) meV to the conduction band. Resistivity in Na doped ZnO crystals increases up to (4–5) orders of magnitude at room temperature.

  3. Preparation, structural and optical characterization of ZnO, ZnO: Al nanopowder

    SciTech Connect

    Mohan, R. Raj; Rajendran, K.; Sambath, K.

    2014-01-28

    In this paper, ZnO and ZnO:Al nanopowders have been synthesized by low cost hydrothermal method. Zinc nitrate, hexamethylenetetramine (HMT) and aluminium nitrate are used as precursors for ZnO and AZO with different molar ratios. The structural and optical characterization of doped and un-doped ZnO powders have been investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDAX), photoluminescence (PL) and ultra violet visible (UV-Vis) absorption studies. The SEM results show that the hydrothermal synthesis can be used to obtain nanoparticles with different morphology. It is observed that the grain size of the AZO nanoparticles increased with increasing of Al concentration. The PL measurement of AZO shows that broad range of green emission around 550nm with high intensity. The green emission resulted mainly because of intrinsic defects.

  4. Spin noise spectroscopy of ZnO

    SciTech Connect

    Horn, H.; Berski, F.; Hübner, J.; Oestreich, M.; Balocchi, A.; Marie, X.; Mansur-Al-Suleiman, M.; Bakin, A.; Waag, A.

    2013-12-04

    We investigate the thermal equilibrium dynamics of electron spins bound to donors in nanoporous ZnO by optical spin noise spectroscopy. The spin noise spectra reveal two noise contributions: A weak spin noise signal from undisturbed localized donor electrons with a dephasing time of 24 ns due to hyperfine interaction and a strong spin noise signal with a spin dephasing time of 5 ns which we attribute to localized donor electrons which interact with lattice defects.

  5. Use of Local {sup 111}In-Capromab Pendetide Scan Results to Predict Outcome After Salvage Radiotherapy for Prostate Cancer

    SciTech Connect

    Koontz, Bridget F. Mouraviev, Vladimir; Johnson, Jeffrey L.; Mayes, Janice; Chen, Stephanie H.; Wong, Terence Z.; Anscher, Mitchell S.; Sun, Leon; Moul, Judd; Polascik, Thomas J.

    2008-06-01

    Purpose: The {sup 111}In-capromab pendetide scan (ProstaScint; Cytogen Corp., Princeton NJ) is approved by the Food and Drug Administration to evaluate increasing prostate-specific antigen (PSA) levels after radical prostatectomy. This study evaluated the role of prostate bed {sup 111}In-capromab pendetide scan findings to predict response to salvage radiotherapy (RT). Methods and Materials: Forty patients who had PSA recurrence after radical prostatectomy and a {sup 111}In-capromab pendetide scan immediately before salvage prostate bed RT (median, 66 Gy) were identified from the Duke Prostate Center database. Patients with distant uptake of capromab pendetide or long-term androgen deprivation therapy were excluded. Median follow-up after salvage RT was 2.7 years. Patient demographic, clinical, and pathologic characteristics; PSA values; and {sup 111}In-capromab pendetide scan results were retrospectively analyzed. A PSA failure after salvage RT was defined as PSA level greater than 0.2 ng/ml. Data were combined with other published results in a secondary pooled analysis of 106 patients. Results: {sup 111}In-Capromab pendetide findings included 20 patients with negative scan results and 20 with locally positive scan results. Two-year progression-free survival rates were 60% for patients with a negative scan result and 74% for those with a locally positive scan result (p = 0.49). Combined analysis did not show a difference in outcome based on local {sup 111}In-capromab pendetide scan result. Conclusion: For patients without distant signal detected by using {sup 111}In-capromab pendetide scan, patients with locally positive scan findings did not have statistically different progression-free survival than those with a negative scan result, suggesting that salvage RT may be successful in patients with either a locally positive or negative {sup 111}In-capromab pendetide scan result.

  6. Kinetics and sites of destruction of /sup 111/In-oxine-labeled platelets in idiopathic thrombocytopenic purpura: a quantitative study

    SciTech Connect

    Heyns, A.D.; Loetter, M.G.; Badenhorst, P.N.; de Kock, F.; Pieters, H.; Herbst, C.; van Reenen, O.R.; Kotze, H.; Minnaar, P.C.

    1982-04-01

    Kinetics and quantification of the sites of destruction of /sup 111/In-oxine-labeled autologous platelets were investigated in eight patients with idiopathic thrombocytopenic purpura. The mean platelet count was 17 +/- 9 X 10(9)/liter; platelets were separated by differential centrifugation and labeled with 5.6 +/- 2.5 MBq /sup 111/In. Whole body and organ /sup 111/In-platelet distribution was quantitated with a scintillation camera and a computer-assisted imaging system acquisition matrix. Areas of interest were selected with the computer and organ /sup 111/In-radioactivity expressed as a percentage of whole body activity. Mean platelet survival was 49.5 +/- 29.6 hr and the survival curves were exponential. Equilibrium percentage organ /sup 111/In-radioactivity was (normal values in parentheses): spleen 33.7 +/- 8.8 (31.1 +/- 10.2); liver 16.1 +/- 9.5 (13.1 +/- 1.3); thorax 22.8 +/- 3.7 (28.2 +/- 5.6). Percentage organ /sup 111/In-activity at the time when labeled platelets had disappeared from the circulation was: spleen 44.5 +/- 16.4 (40 +/- 16); liver 16.0 +/- 11.5 (32.4 +/- 7.2); thorax 19.7 +/- 6.0 (17.7 +/- 10.3). Thorax activity corresponds to bone marrow radioactivity. Three patterns of platelet sequestration were evident. Three patients had mainly splenic sequestration, two mainly hepatic sequestration, and three diffuse reticuloendothelial system sequestration with a major component of platelets destroyed in the bone marrow. Splenectomy was performed in two patients. The pattern of /sup 111/In-platelet sequestration was not predictive of response of glucocorticoid therapy or indicative of the necessity for splenectomy. Quantitative /sup 111/In-labeled autologous platelet kinetic studies provide a new tool for the investigation of platelet disorders.U

  7. Internal radiotherapy and dosimetric study for 111In/ 177Lu-pegylated liposomes conjugates in tumor-bearing mice

    NASA Astrophysics Data System (ADS)

    Wang, Hsin-Ell; Yu, Hung-Man; Lu, Yi-Ching; Heish, Ning-Ning; Tseng, Yun-Long; Huang, Kuang-Liang; Chuang, Kuo-Tang; Chen, Chin-Hsiung; Hwang, Jeng-Jong; Lin, Wuu-Jyh; Wang, Shyh-Jen; Ting, Gann; Whang-Peng, Jacqueline; Deng, Win-Ping

    2006-12-01

    In vivo characterization and dosimetric analysis has been performed to evaluate the potential of pegylated liposomes as carriers of radionuclides in tumor internal radiotherapy. MethodsThe DTPA/PEG-liposomes were synthesized with a medium size of 110 nm, conjugated with 111In/ 177Lu-(oxine) 3 to afford 111In/ 177Lu-liposome. The stability of 111In/ 177Lu-liposome in serum was investigated. The biodistribution, scintigraphic imaging and pharmacokinetics of 111In/ 177Lu-liposomes after intravenous(i.v.) injection into C-26 tumor-bearing BALB/cByJ mice were studied. Radiation dose was estimated by MIRD-III program. ResultsThe incorporation efficiency of 111In/ 177Lu into liposomes was 95%. After incubation at 37 °C for 72 h in serum, more than 83% of radioactivity was still retained in the intact 111In/ 177Lu-liposomes. The biodistribution of 111In-liposomes showed that the radioactivity in the blood decreased from 23.14±8.16%ID/g at 1 h to 0.02±0.00%ID/g at 72 h post-injection (p.i.), while reaching its maximum accumulation in tumors at 48 h p.i., with half-life in blood of 10.2 h. The results were supported by that of 177Lu-liposomes. Scintigraphic imaging with 111In-liposomes showed unambiguous tumor images at 48 h p.i. Dose estimation showed that the absorbed dose in tumor from 177Lu-liposomes was 5.74×10 -5 Gy/MBq. ConclusionsThis study provides an in vivo characterization and dosimetric evaluation for the use of liposome systems as carriers in targeted radionuclide therapy. The results suggest that adequate tumor targeting as well as dose delivered to tumors could be achieved by the use of radionuclide targeted liposomes.

  8. Synthesis, characterization and photocatalytic activity of PVP stabilized ZnO and modified ZnO nanostructures

    NASA Astrophysics Data System (ADS)

    Bandekar, Gauri; Rajurkar, N. S.; Mulla, I. S.; Mulik, U. P.; Amalnerkar, D. P.; Adhyapak, P. V.

    2013-01-01

    In the present study, ZnO nanostructures have been successfully synthesized by hydrothermal, sonochemical and precipitation methods using polyvinyl pyrrolidone (PVP) as the capping agent. The ZnO nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), UV-Visible spectroscopy and photoluminescence (PL) techniques. The XRD results revealed the hexagonal wurtzite structure of the ZnO nanostructures for all the samples. Furthermore, the morphology of the ZnO particles was obtained from FESEM micrographs. Particles prepared by hydrothermal method were found to be rice grain shaped and that prepared by precipitation and sonochemical methods were spherical shaped. Sunlight driven photocatalytic degradation of methylene blue (MB) was studied for ZnO nanostructures synthesized by various methods. The ZnO nanostructures were further decorated with Ag nanoparticles to enhance its dye degradation efficiency. The Ag decorated ZnO nanoparticles exhibited a higher degradation rate as compared to pure ZnO nanoparticles which was independent of pH. Since this process of dye degradation relies on the degradation of dye due to oxidation by highly reactive hydroxyl radicals, there are many factors which affect the efficiency of this process. Hence a study was conducted on the effect of various parameters on ZnO viz amount of catalyst, reaction pH and concentration of MB dye.

  9. Clinically based implant selection.

    PubMed

    Fugazzotto, P A

    1999-01-01

    A hierarchy of implant selection is presented, based on overcoming specific clinical challenges in a variety of situations, including maximization of the esthetic, comfort, and functional potentials of therapy. PMID:10709488

  10. Breast reconstruction - implants

    MedlinePlus

    ... stages, or surgeries. During the first stage, a tissue expander is used. An implant is placed during the ... a pouch under your chest muscle. A small tissue expander is placed in the pouch. The expander is ...

  11. [Silicone breast implants].

    PubMed

    Nielsen, M; Brandt, B; Breiting, V B; Christensen, L H; Thomsen, J L

    1989-12-18

    A brief review of the use of silicone breast implants, their structure, methods of implantation and complications is presented. Acute complications are rare, being mainly infection and hematoma. Long-term complications, on the contrary, are common, consisting mainly of capsular contracture around the prosthesis with subsequent pain and deformation of the breast. More rarely silicone granulomas form, and prosthesis rupture or herniation occurs. The importance of silicone leakage for these complications is discussed separately as well as the treatment of and prevention of capsular contracture and demonstration of silicone in tissue. A critical attitude towards the use of silicone breast implants, when these are used for purely cosmetic purposes, is recommended at present. New improved types of silicone breast implants are currently being tested clinically. PMID:2692262

  12. Peri-Implant Diseases

    MedlinePlus

    ... and flossing and regular check-ups from a dental professional. Other risks factors for developing peri-implant disease include previous periodontal disease diagnosis, poor plaque control, smoking , and diabetes . It is essential to routinely ...

  13. Biocompatibility of surgical implants

    NASA Technical Reports Server (NTRS)

    Kaelble, D. H.

    1979-01-01

    Method of selecting biocompatible materials for surgical implants uses fracture mechanic relationships and surface energies of candidate materials in presence of blood plasma. Technique has been used to characterize 190 materials by parameters that reflect their biocompatibility.

  14. Risks of Breast Implants

    MedlinePlus

    ... larger and longer than these conducted so far. Breastfeeding Some women who undergo breast augmentation can successfully ... breast implant silicone shell into breast milk during breastfeeding. Although there are currently no established methods for ...

  15. Implantable microscale neural interfaces.

    PubMed

    Cheung, Karen C

    2007-12-01

    Implantable neural microsystems provide an interface to the nervous system, giving cellular resolution to physiological processes unattainable today with non-invasive methods. Such implantable microelectrode arrays are being developed to simultaneously sample signals at many points in the tissue, providing insight into processes such as movement control, memory formation, and perception. These electrode arrays have been microfabricated on a variety of substrates, including silicon, using both surface and bulk micromachining techniques, and more recently, polymers. Current approaches to achieving a stable long-term tissue interface focus on engineering the surface properties of the implant, including coatings that discourage protein adsorption or release bioactive molecules. The implementation of a wireless interface requires consideration of the necessary data flow, amplification, signal processing, and packaging. In future, the realization of a fully implantable neural microsystem will contribute to both diagnostic and therapeutic applications, such as a neuroprosthetic interface to restore motor functions in paralyzed patients. PMID:17252207

  16. Superelastic Orthopedic Implant Coatings

    NASA Astrophysics Data System (ADS)

    Fournier, Eric; Devaney, Robert; Palmer, Matthew; Kramer, Joshua; El Khaja, Ragheb; Fonte, Matthew

    2014-07-01

    The demand for hip and knee replacement surgery is substantial and growing. Unfortunately, most joint replacement surgeries will fail within 10-25 years, thereby requiring an arduous, painful, and expensive revision surgery. To address this issue, a novel orthopedic implant coating material ("eXalt") has been developed. eXalt is comprised of super elastic nitinol wire that is knit into a three-dimensional spacer fabric structure. eXalt expands in vivo to conform to the implantation site and is porous to allow for bone ingrowth. The safety and efficacy of eXalt were evaluated through structural analysis, mechanical testing, and a rabbit implantation model. The results demonstrate that eXalt meets or exceeds the performance of current coating technologies with reduced micromotion, improved osseointegration, and stronger implant fixation in vivo.

  17. Implant treatment planning: endodontic considerations.

    PubMed

    Simonian, Krikor; Frydman, Alon; Verdugo, Fernando; Roges, Rafael; Kar, Kian

    2014-12-01

    Implants are a predictable and effective method for replacing missing teeth. Some clinicians have advocated extraction and replacement of compromised but treatable teeth on the assumption that implants will outperform endodontically and/or periodontally treated teeth. However, evidence shows that conventional therapy is as effective as implant treatment. With data on implants developing complications long term and a lack of predictable treatment for peri-implantitis, retaining and restoring the natural dentition should be the first choice when possible. PMID:25928961

  18. Ion implantation at elevated temperatures

    SciTech Connect

    Lam, N.Q.; Leaf, G.K.

    1985-11-01

    A kinetic model has been developed to investigate the synergistic effects of radiation-enhanced diffusion, radiation-induced segregation and preferential sputtering on the spatial redistribution of implanted solutes during implantation at elevated temperatures. Sample calculations were performed for Al and Si ions implanted into Ni. With the present model, the influence of various implantation parameters on the evolution of implant concentration profiles could be examined in detail.

  19. Mixed Zn and O substitution of Co and Mn in ZnO

    SciTech Connect

    Pereira, L. M. C.; Wahl, U.; Correia, J. G.; Decoster, S.; Amorim, L. M.; Vantomme, A.; Silva, M. R. da; Araujo, J. P.

    2011-09-15

    The physical properties of an impurity atom in a semiconductor are primarily determined by the lattice site it occupies. In general, this occupancy can be correctly predicted based on chemical intuition, but not always. We report on one such exception in the dilute magnetic semiconductors Co- and Mn-doped ZnO, experimentally determining the lattice location of Co and Mn using {beta}{sup -}-emission channeling from the decay of radioactive {sup 61}Co and {sup 56}Mn implanted at the ISOLDE facility at CERN. Surprisingly, in addition to the majority substituting for Zn, we find up to 18% (27%) of the Co (Mn) atoms in O sites, which is virtually unaffected by thermal annealing up to 900 deg. C. We discuss how this anion site configuration, which had never been considered before for any transition metal in any metal oxide material, may in fact have a low formation energy. This suggests a change in paradigm regarding transition-metal incorporation in ZnO and possibly other oxides and wide-gap semiconductors.

  20. Biomaterials in cochlear implants

    PubMed Central

    Stöver, Timo; Lenarz, Thomas

    2011-01-01

    The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces. As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices. This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development. PMID:22073103

  1. [Implantable materials (author's transl)].

    PubMed

    Schaldach, M

    1975-11-01

    There is a steadily increasing importance of implants used as substitutions for body functions which have been impaired due to disease, natural abrasion or accident. With the present state of the art, the limitations for the application of surgical substitutions are due to insufficient properties of biomaterials with regard to specific applications as well as to deficiencies in design and function of the implants used. The basis for the improvement and new development of implants is therefore a functionally adequate design in which the specific properties of the material are taken into account with regard to the individual requirements of the implantation site. For orthopedic implants, materials have to be developed which are to a large extent corrosion and degradation resistant, and withstand high mechanical stress. For implants in the cardiovascular system, compatibility with blood is most significant. Present research in this field is concentrated on efforts to improve the thromboresistivity of conventional polymers by different kinds of surface treatments. One possibility is to influence actively the electrochemical interactions between material and blood components, e.g. by the use of redox catalysts. PMID:1107653

  2. Local investigation of hyperfine interactions in pure and Co-doped ZnO

    NASA Astrophysics Data System (ADS)

    Mercurio, M. E.; Carbonari, A. W.; Cordeiro, M. R.; Saxena, R. N.; D'Agostino, L. Z.

    2010-05-01

    In the present work bulk samples of pure as well as Co-doped ZnO with different concentrations were prepared by sol-gel method from highly pure metallic Zn (99.9999%) and Co (99.9999%). The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray microanalysis (EDS) and perturbed gamma-gamma angular correlation (PAC) spectroscopy. Carrier-free 111In nuclei were introduced during preparation of the samples and used as probe nuclei at Zn sites for PAC measurements. PAC results show that both pure and Zn1-xCoxO ( x≤0.15) samples have the same electric quadrupole frequency when Co-doped samples are annealed in air, argon or nitrogen atmosphere at 1173 K. SEM and EDS results showed that Co-doped samples are homogeneous without any secondary Co phases. These observations indicate that Co ions are substituted for Zn ions and have a similar electronic structure of Zn ions. A weak local magnetism was observed at temperatures below about 300 K for Co concentration of 10% when sample was annealed in Nitrogen.

  3. Radioimmunodetection in rhabdo- and leiomyosarcoma with 111In-anti-myosin monoclonal antibody complex.

    PubMed

    Planting, A; Verweij, J; Cox, P; Pillay, M; Stoter, G

    1990-02-01

    In patients with rhabdo- and leiomyosarcoma a radioimmunodiagnostic study was performed with 111In labeled F(ab) fragments of a monoclonal antibody against myosin. Eight patients with rhabdomyosarcoma and 18 patients with leiomyosarcoma were studied. Scanning was performed at 4, 24, and 48 h after administration of 74 MBeq of the antibody complex. A high uptake with a tumor:background ratio of 10:1 was observed in several patients with rhabdomyosarcoma but the results were less accurate in leiomyosarcoma. PMID:2297748

  4. Role of ZnO thin film in the vertically aligned growth of ZnO nanorods by chemical bath deposition

    NASA Astrophysics Data System (ADS)

    Son, Nguyen Thanh; Noh, Jin-Seo; Park, Sungho

    2016-08-01

    The effect of ZnO thin film on the growth of ZnO nanorods was investigated. ZnO thin films were sputter-deposited on Si substrate with varying the thickness. ZnO nanorods were grown on the thin film using a chemical bath deposition (CBD) method at 90 °C. The ZnO thin films showed granular structure and vertical roughness on the surface, which facilitated the vertical growth of ZnO nanorods. The average grain size and the surface roughness of ZnO film increased with an increase in film thickness, and this led to the increase in both the average diameter and the average length of vertically grown ZnO nanorods. In particular, it was found that the average diameter of ZnO nanorods was very close to the average grain size of ZnO thin film, confirming the role of ZnO film as a seed layer for the vertical growth of ZnO nanorods. The CBD growth on ZnO seed layers may provide a facile route to engineering vertically aligned ZnO nanorod arrays.

  5. Fast synthesize ZnO quantum dots via ultrasonic method.

    PubMed

    Yang, Weimin; Zhang, Bing; Ding, Nan; Ding, Wenhao; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

    2016-05-01

    Green emission ZnO quantum dots were synthesized by an ultrasonic sol-gel method. The ZnO quantum dots were synthesized in various ultrasonic temperature and time. Photoluminescence properties of these ZnO quantum dots were measured. Time-resolved photoluminescence decay spectra were also taken to discover the change of defects amount during the reaction. Both ultrasonic temperature and time could affect the type and amount of defects in ZnO quantum dots. Total defects of ZnO quantum dots decreased with the increasing of ultrasonic temperature and time. The dangling bonds defects disappeared faster than the optical defects. Types of optical defects first changed from oxygen interstitial defects to oxygen vacancy and zinc interstitial defects. Then transformed back to oxygen interstitial defects again. The sizes of ZnO quantum dots would be controlled by both ultrasonic temperature and time as well. That is, with the increasing of ultrasonic temperature and time, the sizes of ZnO quantum dots first decreased then increased. Moreover, concentrated raw materials solution brought larger sizes and more optical defects of ZnO quantum dots. PMID:26611814

  6. Implant interactions with orthodontics.

    PubMed

    Celenza, Frank

    2012-09-01

    Many situations arise in which orthodontic therapy in conjunction with implant modalities is beneficial, relevant or necessary. These situations might entail orthodontic treatment preparatory to the placement of an implant, such as in the site preparation for implant placement. Traditionally, this has been somewhat well understood, but there are certain guidelines that must be adhered to as well as diagnostic steps that must be followed. Provision of adequate space for implant placement is of paramount importance, but there is also the consideration of tissue manipulation and remodeling which orthodontic therapy can achieve very predictably and orthodontists should be well versed in harnessing and employing this modality of site preparation. In this way, hopeless teeth that are slated for extraction can still be utilized by orthodontic extraction to augment tissues, both hard and soft, thereby facilitating site development. On the corollary, and representing a significant shift in treatment sequencing, there are many situations in which orthodontic mechanotherapy can be simplified, expedited, and facilitated by the placement of an implant and utilization as an integral part of the mechanotherapy. Implants have proven to provide excellent anchorage, and have resulted in a new class of anchorage known as "absolute anchorage". Implants can be harnessed as anchors both in a direct and indirect sense, depending upon the dictates of the case. Further, this has led to the development of orthodontic miniscrew systems and techniques, which can have added features such as flexibility in location and placement, as well as ease of use and removal. As orthodontic appliances evolve, the advent of aligner therapy has become mainstream and well accepted, and many of the aforementioned combined treatment modalities can and should be incorporated into this relatively new treatment modality as well. PMID:23040348

  7. Ultrasonic synthesis of fern-like ZnO nanoleaves and their enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ma, Qing Lan; Xiong, Rui; Zhai, Bao-gai; Huang, Yuan Ming

    2015-01-01

    Two-dimensional fern-like ZnO nanoleaves were synthesized by ultrasonicating zinc microcrystals in water. The morphology, crystal structure, optical property and photocatalytic activity of the fern-like ZnO nanoleaves were characterized with scanning electron microscopy, X-ray diffraction, transmission electron microscopy, photoluminescence spectroscopy and ultraviolet-visible spectroscopy, respectively. It is found that one fern-like ZnO nanoleaf is composed of one ZnO nanorod as the central trunk and a number of ZnO nanoplates as the side branches in opposite pairs along the central ZnO nanorod. The central ZnO nanorod in the fern-like nanoleaves is about 1 μm long while the side-branching ZnO nanoplates are about 100 nm long and 20 nm wide. Further analysis has revealed that ZnO nanocrystals are the building blocks of the central ZnO nanorod and the side-branching ZnO nanoplates. Under identical conditions, fern-like ZnO nanoleaves exhibit higher photocatalytic activity in photodegrading methyl orange in aqueous solution than spherical ZnO nanocrystals. The first-order photocatalytic rate constant of the fern-like ZnO nanoleaves is about four times as large as that of the ZnO nanoparticles. The branched architecture of the hierarchical nanoleaves is suggested be responsible for the enhanced photocatalytic activity of the fern-like ZnO nanoleaves.

  8. Fabrication of a ZnO Pyroelectric Sensor

    PubMed Central

    Hsiao, Chun-Ching; Huang, Kuo-Yi; Hu, Yuh-Chung

    2008-01-01

    This paper proposes a two-step radio frequency (RF) sputtering process to form a ZnO film for pyroelectric sensors. It is shown that the two-step sputtering process with a lower power step followed by a higher power step can significantly improve the voltage responsivity of the ZnO pyroelectric sensor. The improvement is attributed mainly to the formation of ZnO film with a strongly preferred orientation towards the c-axis. Furthermore, a nickel film deposited onto the uncovered parts of the ZnO film can effectively improve the voltage responsivity at higher modulating frequencies since the nickel film can enhance the incident energy absorption of the ZnO layer.

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

    PubMed Central

    2011-01-01

    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.

  10. Review of zincblende ZnO: Stability of metastable ZnO phases

    NASA Astrophysics Data System (ADS)

    Ashrafi, A.; Jagadish, C.

    2007-10-01

    Common II-VI compound semiconducting materials are stable thermodynamically with zincblende phase, while the II-O materials such as zinc oxide (ZnO) and beryllium oxide (BeO) are stable with wurtzite phase, and cadmium oxide (CdO) and magnesium oxide (MgO) are stable in rocksalt phase. This phase disharmony in the same material family laid a challenge for the basic physics and in practical applications in optoelectronic devices, where ternary and quaternary compounds are employed. Thermodynamically the zincblende ZnO is a metastable phase which is free from the giant internal electric fields in the [001] directions and has an easy cleavage facet in the ⟨110⟩ directions for laser cavity fabrication that combined with evidence for the higher optical gain. The zincblende materials also have lower ionicity that leads to the lower carrier scattering and higher doping efficiencies. Even with these outstanding features in the zincblende materials, the growth of zincblende ZnO and its fundamental properties are still limited. In this paper, recent progress in growth and fundamental properties of zincblende ZnO material has been reviewed.