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Sample records for nanoparticle embedded silicon

  1. Ordered arrays of embedded Ga nanoparticles on patterned silicon substrates.

    PubMed

    Bollani, M; Bietti, S; Frigeri, C; Chrastina, D; Reyes, K; Smereka, P; Millunchick, J M; Vanacore, G M; Burghammer, M; Tagliaferri, A; Sanguinetti, S

    2014-05-23

    We fabricate site-controlled, ordered arrays of embedded Ga nanoparticles on Si, using a combination of substrate patterning and molecular-beam epitaxial growth. The fabrication process consists of two steps. Ga droplets are initially nucleated in an ordered array of inverted pyramidal pits, and then partially crystallized by exposure to an As flux, which promotes the formation of a GaAs shell that seals the Ga nanoparticle within two semiconductor layers. The nanoparticle formation process has been investigated through a combination of extensive chemical and structural characterization and theoretical kinetic Monte Carlo simulations. PMID:24784353

  2. Gold nanoparticles embedded silicon channel biosensor for improved sensitivity

    NASA Astrophysics Data System (ADS)

    Chang, H. Y.; Arshad, M. K. Md.; M. Nuzaihan M., N.; Fathil, M. F. M.; Hashim, U.

    2016-07-01

    This project discusses the fabrication steps of a biosensor device on silicon-on-insulator (SOI) wafer. Conventional photolithography technique is used to fabricate the device. The gold nanoparticles (GNPs) are then used to enhance the sensitivity of the device. By incorporating the GNPs, it is expected to get higher current compared with the device without GNPs due to better conductivity of gold and higher volume-to-ratio. Hence, with the addition of GNPs, it may boost up the signal and enhance the sensitivity of the device.

  3. Control of silicon nanoparticle size embedded in silicon oxynitride dielectric matrix

    SciTech Connect

    Ehrhardt, F.; Ferblantier, G.; Muller, D.; Slaoui, A.; Ulhaq-Bouillet, C.; Rinnert, H.

    2013-07-21

    In this study, silicon rich silicon oxynitride layers containing more than 15% nitrogen were deposited by electron cyclotron resonance assisted plasma enhanced vapor deposition in order to form silicon nanoparticles after a high temperature thermal annealing. The effect of the flows of the precursor gases on the composition and the structural properties of the layers was assessed by Rutherford backscattering spectroscopy, elastic recoil detection analysis, and infrared spectroscopic measurements. The morphological and crystallinity properties were investigated by energy filtered transmission electron microscopy and Raman spectroscopy. We show that the excess of silicon in the silicon oxynitride layer controls the silicon nanoparticles size. On the other hand, the crystalline fraction of particles is found to be strongly correlated to the nanoparticle size. Finally, the photoluminescence measurements show that it is also possible to tune the photoluminescence peak position between 400 and 800 nm and its intensity by changing the silicon excess in the silicon rich silicon oxynitride matrix.

  4. Synthesis and photoluminescence studies of silicon nanoparticles embedded in silicon compound films

    NASA Astrophysics Data System (ADS)

    Huang, Rao; Ma, Li-Bo; Ye, Jian-Ping; Wang, Yong-Qian; Cao, Ze-Xian

    2008-06-01

    High-density silicon nanoparticles with well-controlled sizes were grown onto cold substrates in amorphous SiN x and SiC matrices by plasma-enhanced chemical vapor deposition. Strong, tunable photoluminescence across the whole visible light range has been measured at room temperature from such samples without invoking any post-treatment, and the spectral features can find a qualitative explanation in the framework of quantum confinement effect. Moreover, the decay time was for the first time brought down to within one nanosecond. These excellent features make the silicon nanostructures discussed here very promising candidates for light-emitting units in photonic and optoelectronic applications.

  5. In-Situ TEM Study Of Lithiation Behavior Of Silicon Nanoparticles Attached To And Embedded In A Carbon Matrix

    SciTech Connect

    Gu, Meng; Li, Ying; Li, Xiaolin; Hu, Shenyang Y.; Zhang, Xiangwu; Xu, Wu; Thevuthasan, Suntharampillai; Baer, Donald R.; Zhang, Jiguang; Liu, Juan; Wang, Chong M.

    2012-08-23

    Rational design of silicon and carbon nanocomposite with a special topological feature has been demonstrated to be a feasible way for mitigating the capacity fading associated with the large volume change of silicon anode in lithium ion batteries. Although the lithiation behavior of silicon and carbon as individual component has been well understood, lithium ion transport behavior across a network of silicon and carbon are still lacking. In this paper, we probe the lithiation behavior of silicon nanoparticles attached to and embedded in a carbon nanofiber using in-situ TEM and continuum mechanical calculation. We found that aggregated silicon nanoparticles show contact flattering upon initial lithiation, which is characteristically analogous to the classic sintering of powder particles by neck-growth mechanism. As compared with the surface-attached silicon particle, particles embedded in the carbon matrix show delayed lithiation. Depending on the strength of the carbon matrix, lithiation of the embedded silicon nanoparticle can lead to the fracture of the carbon fiber. These observations provide insights on lithium ion transport in the network structured composite of silicon and carbon, and ultimately provide fundamental guidance for mitigating the failure of battery due to the large volume change of silicon anode.

  6. Enhanced magnetic resonance contrast of iron oxide nanoparticles embedded in a porous silicon nanoparticle host

    NASA Astrophysics Data System (ADS)

    Kinsella, Joseph; Ananda, Shalini; Andrew, Jennifer; Grondek, Joel; Chien, Miao-Ping; Scandeng, Miriam; Gianneschi, Nathan; Ruoslahti, Erkki; Sailor, Michael

    2013-02-01

    In this report, we prepared a porous Si nanoparticle with a pore morphology that facilitates the proximal loading and alignment of magnetite nanoparticles. We characterized the composite materials using superconducting quantum interference device magnetometry, dynamic light scattering, transmission electron microscopy, and MRI. The in vitro cytotoxicity of the composite materials was tested using cell viability assays on human liver cancer cells and rat hepatocytes. An in vivo analysis using a hepatocellular carcinoma (HCC) Sprague Dawley rat model was used to determine the biodistribution properties of the material, while naïve Sprague Dawley rats were used to determine the pharmocokinetic properties of the nanomaterials. The composite material reported here demonstrates an injectable nanomaterial that exploits the dipolar coupling of superparamagnetic nanoparticles trapped within a secondary inorganic matrix to yield significantly enhanced MRI contrast. This preparation successfully avoids agglomeration issues that plague larger ferromagnetic systems. A Fe3O4:pSi composite formulation consisting of 25% by mass Fe3O4 yields an maximal T2* value of 556 mM Fe-1 s-1. No cellular (HepG2 or rat hepatocyte cells) or in vivo (rat) toxicity was observed with the formulation, which degrades and is eliminated after 4-8 h in vivo. The ability to tailor the magnetic properties of such materials may be useful for in vivo imaging, magnetic hyperthermia, or drug-delivery applications.

  7. Low power zinc-oxide based charge trapping memory with embedded silicon nanoparticles via poole-frenkel hole emission

    SciTech Connect

    El-Atab, Nazek; Nayfeh, Ammar; Ozcan, Ayse; Alkis, Sabri; Okyay, Ali K.; Department of Electrical and Electronics Engineering, Bilkent University, 06800 Ankara

    2014-01-06

    A low power zinc-oxide (ZnO) charge trapping memory with embedded silicon (Si) nanoparticles is demonstrated. The charge trapping layer is formed by spin coating 2 nm silicon nanoparticles between Atomic Layer Deposited ZnO steps. The threshold voltage shift (ΔV{sub t}) vs. programming voltage is studied with and without the silicon nanoparticles. Applying −1 V for 5 s at the gate of the memory with nanoparticles results in a ΔV{sub t} of 3.4 V, and the memory window can be up to 8 V with an excellent retention characteristic (>10 yr). Without nanoparticles, at −1 V programming voltage, the ΔV{sub t} is negligible. In order to get ΔV{sub t} of 3.4 V without nanoparticles, programming voltage in excess of 10 V is required. The negative voltage on the gate programs the memory indicating that holes are being trapped in the charge trapping layer. In addition, at 1 V the electric field across the 3.6 nm tunnel oxide is calculated to be 0.36 MV/cm, which is too small for significant tunneling. Moreover, the ΔV{sub t} vs. electric field across the tunnel oxide shows square root dependence at low fields (E < 1 MV/cm) and a square dependence at higher fields (E > 2.7 MV/cm). This indicates that Poole-Frenkel Effect is the main mechanism for holes emission at low fields and Phonon Assisted Tunneling at higher fields.

  8. Gold nanoparticles deposited on linker-free silicon substrate and embedded in aluminum Schottky contact.

    PubMed

    Gorji, Mohammad Saleh; Razak, Khairunisak Abdul; Cheong, Kuan Yew

    2013-10-15

    Given the enormous importance of Au nanoparticles (NPs) deposition on Si substrates as the precursor for various applications, we present an alternative approach to deposit Au NPs on linker-free n- and p-type Si substrates. It is demonstrated that, all conditions being similar, there is a significant difference between densities of the deposited NPs on both substrates. The Zeta-potential and polarity of charges surrounding the hydroxylamine reduced seeded growth Au NPs, are determined by a Zetasizer. To investigate the surface properties of Si substrates, contact angle measurement is performed. Field-emission scanning electron microscope is then utilized to distinguish the NPs density on the substrates. Finally, Al/Si Schottky barrier diodes with embedded Au NPs are fabricated, and their structural and electrical characteristics are further evaluated using an energy-filtered transmission electron microscope and current-voltage measurements, respectively. The results reveal that the density of NPs is significantly higher on n-type Si substrate and consequently has more pronounced effects on the electrical characteristics of the diode. It is concluded that protonation of Si-OH group on Si surface in low pH is responsible for the immobilization of Au NPs, which eventually contributes to the lowering of barrier height and enhances the electrical characteristics. PMID:23932085

  9. Effect of well confinement on photoluminescence features from silicon nanoparticles embedded in an SiC/SiN(x) multilayered structure.

    PubMed

    Huang, Rao; Ma, Libo; Du, Yun; Gao, Lei; Li, Chaorong; Yu, Cailan; Ye, Jianping; Cao, Zexian

    2008-06-25

    Light emission from a quantum well-dot structure comprising amorphous Si nanoparticles (∼1.4 nm) embedded in SiC/SiN(x) multilayers (a few tens nm thick for individual sublayers) was investigated. Strong blue-green photoluminescence was measured at room temperature on the as-deposited samples and the spectral profile shows some markedly modulated features. It displays flattened profiles of roughly equal intensity when silicon particles in both nitride and carbide sublayers can be effectively excited, whereas when the nitride sublayer is less effectively activated at longer excitation wavelength the photoluminescence is pinned (here at 500 nm), showing a rather narrow, slowly decreasing profile. The phenomenon of narrowed emission is also observed in the Si-in-SiC multilayer consisting of particles of varying size distributions. Resonance energy transfer processes among particles modified by carrier confinement may provide a reasonable explanation. PMID:21828651

  10. Nanostructured silicon thin films deposited by PECVD in the presence of silicon nanoparticles

    SciTech Connect

    Viera, G.; Cabarrocas, P.R.; Hamma, S.; Sharma, S.N.; Costa, J.; Bertran, E.

    1997-07-01

    Nanostructured silicon thin films have been deposited by plasma enhanced chemical vapor deposition at low substrate temperature (100 C) in the presence of silicon nanoparticles. The nanostructure of the films was revealed by transmission electron microscopy, Raman spectroscopy and X-ray diffraction, which showed ordered silicon domains (1--2 nm) embedded in an amorphous silicon matrix. These ordered domains are due to the particles created in the discharge that contribute to the film growth. One consequence of the incorporation of nanoparticles is the accelerated crystallization of the nanostructured silicon thin films when compared to standard a-Si:H, as shown by the electrical characterization during the annealing.

  11. Solar cell enhancement using metallic nanoparticles embedded in titanium dioxide

    NASA Astrophysics Data System (ADS)

    Burnett, Max A.; Allen, Kenneth W.; Fiddy, Michael A.

    2015-02-01

    In this work we model the effects of depositing gold nanospheres of varying radii and spatial separations onto a 500nm film of silicon in an effort to couple more light into silicon through the localized surface plasmon resonance (LSPR) of the nanoparticles. To further enhance the field at the interface, we study the effect of embedding the spheres within the dielectrics air, NBK7, and titanium dioxide (TiO2). The modeling is done through finite element analysis via COMSOL over the radiation spectrum (0.4μm 1.5μm) of the sun. A positive size dependency of the light coupled into silicon and the radii of the spheres is found and analyzed. Use of dielectrics greater than air, NBK7 and TiO2, results in greater field enhancement at the silicon interface.

  12. Collective optical Kerr effect exhibited by an integrated configuration of silicon quantum dots and gold nanoparticles embedded in ion-implanted silica.

    PubMed

    Torres-Torres, C; López-Suárez, A; Can-Uc, B; Rangel-Rojo, R; Tamayo-Rivera, L; Oliver, A

    2015-07-24

    The study of the third-order optical nonlinear response exhibited by a composite containing gold nanoparticles and silicon quantum dots nucleated by ion implantation in a high-purity silica matrix is presented. The nanocomposites were explored as an integrated configuration containing two different ion-implanted distributions. The time-resolved optical Kerr gate and z-scan techniques were conducted using 80 fs pulses at a 825 nm wavelength; while the nanosecond response was investigated by a vectorial two-wave mixing method at 532 nm with 1 ns pulses. An ultrafast purely electronic nonlinearity was associated to the optical Kerr effect for the femtosecond experiments, while a thermal effect was identified as the main mechanism responsible for the nonlinear optical refraction induced by nanosecond pulses. Comparative experimental tests for examining the contribution of the Au and Si distributions to the total third-order optical response were carried out. We consider that the additional defects generated by consecutive ion irradiations in the preparation of ion-implanted samples do not notably modify the off-resonance electronic optical nonlinearities; but they do result in an important change for near-resonant nanosecond third-order optical phenomena exhibited by the closely spaced nanoparticle distributions. PMID:26135968

  13. Collective optical Kerr effect exhibited by an integrated configuration of silicon quantum dots and gold nanoparticles embedded in ion-implanted silica

    NASA Astrophysics Data System (ADS)

    Torres-Torres, C.; López-Suárez, A.; Can-Uc, B.; Rangel-Rojo, R.; Tamayo-Rivera, L.; Oliver, A.

    2015-07-01

    The study of the third-order optical nonlinear response exhibited by a composite containing gold nanoparticles and silicon quantum dots nucleated by ion implantation in a high-purity silica matrix is presented. The nanocomposites were explored as an integrated configuration containing two different ion-implanted distributions. The time-resolved optical Kerr gate and z-scan techniques were conducted using 80 fs pulses at a 825 nm wavelength; while the nanosecond response was investigated by a vectorial two-wave mixing method at 532 nm with 1 ns pulses. An ultrafast purely electronic nonlinearity was associated to the optical Kerr effect for the femtosecond experiments, while a thermal effect was identified as the main mechanism responsible for the nonlinear optical refraction induced by nanosecond pulses. Comparative experimental tests for examining the contribution of the Au and Si distributions to the total third-order optical response were carried out. We consider that the additional defects generated by consecutive ion irradiations in the preparation of ion-implanted samples do not notably modify the off-resonance electronic optical nonlinearities; but they do result in an important change for near-resonant nanosecond third-order optical phenomena exhibited by the closely spaced nanoparticle distributions.

  14. Organic memory device with polyaniline nanoparticles embedded as charging elements

    NASA Astrophysics Data System (ADS)

    Kim, Yo-Han; Kim, Minkeun; Oh, Sewook; Jung, Hunsang; Kim, Yejin; Yoon, Tae-Sik; Kim, Yong-Sang; Ho Lee, Hyun

    2012-04-01

    Polyaniline nanoparticles (PANI NPs) were synthesized and fabricated as charging elements for organic memory devices. The PANI NPs charging layer was self-assembled by epoxy-amine bonds between 3-glycidylpropyl trimethoxysilane functionalized dielectrics and PANI NPs. A memory window of 5.8 V (ΔVFB) represented by capacitance-voltage hysteresis was obtained for metal-pentacene-insulator-silicon capacitor. In addition, program/erase operations controlled by gate bias (-/+90 V) were demonstrated in the PANI NPs embedded pentacene thin film transistor device with polyvinylalcohol dielectric on flexible polyimide substrate. These results can be extended to development of fully organic-based electronic device.

  15. Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications

    SciTech Connect

    Akhter, Perveen; Huang, Mengbing Spratt, William; Kadakia, Nirag; Amir, Faisal

    2015-03-28

    Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ∼50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3–10% lower or higher than that of silicon for wavelengths below or beyond ∼815–900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10–100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics.

  16. Tailoring the optical constants in single-crystal silicon with embedded silver nanostructures for advanced silicon photonics applications

    NASA Astrophysics Data System (ADS)

    Akhter, Perveen; Huang, Mengbing; Spratt, William; Kadakia, Nirag; Amir, Faisal

    2015-03-01

    Plasmonic effects associated with metal nanostructures are expected to hold the key to tailoring light emission/propagation and harvesting solar energy in materials including single crystal silicon which remains the backbone in the microelectronics and photovoltaics industries but unfortunately, lacks many functionalities needed for construction of advanced photonic and optoelectronics devices. Currently, silicon plasmonic structures are practically possible only in the configuration with metal nanoparticles or thin film arrays on a silicon surface. This does not enable one to exploit the full potential of plasmonics for optical engineering in silicon, because the plasmonic effects are dominant over a length of ˜50 nm, and the active device region typically lies below the surface much beyond this range. Here, we report on a novel method for the formation of silver nanoparticles embedded within a silicon crystal through metal gettering from a silver thin film deposited at the surface to nanocavities within the Si created by hydrogen ion implantation. The refractive index of the Ag-nanostructured layer is found to be 3-10% lower or higher than that of silicon for wavelengths below or beyond ˜815-900 nm, respectively. Around this wavelength range, the optical extinction values increase by a factor of 10-100 as opposed to the pure silicon case. Increasing the amount of gettered silver leads to an increased extinction as well as a redshift in wavelength position for the resonance. This resonance is attributed to the surface plasmon excitation of the resultant silver nanoparticles in silicon. Additionally, we show that the profiles for optical constants in silicon can be tailored by varying the position and number of nanocavity layers. Such silicon crystals with embedded metal nanostructures would offer novel functional base structures for applications in silicon photonics, optoelectronics, photovoltaics, and plasmonics.

  17. Tunable Luminescence of Silicon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vladimirov, A.; Korovin, S.; Surkov, A.; Kelm, E.; Pustovoy, V.

    2010-10-01

    The luminescent properties of silicon nanoparticles were studied. The particles were prepared by laser pyrolysis of silane in a gas flow reactor. Initially non-luminescent particles were treated by the chemical etching in mixture of fluoric and nitric acids. The high and stable photoluminescence from etched particles was observed. With increasing etching time, the PL peak shifted to blue region. With decreasing of the excitation wavelength from 660 nm to 365 nm, the PL peak shifted from 820 nm to 660 nm. This allows us to use the silicon based particles for wavelength selected excitation in some practical application.

  18. Systematic characterisation of silicon-embedded accelerometers for mechanomyography.

    PubMed

    Silva, J; Chau, T; Naumann, S; Heim, W

    2003-05-01

    Silicon soft suction sockets (roll-on sleeves) currently used in passive prostheses for below-elbow amputees could also be used in externally powered prostheses, enhancing their functionality and comfort. However, as it is extremely difficult to hold currently used electromyography (EMG) sensors in place reliably within a silicon socket, an alternative measurement of muscular activity as the control input is necessary. Mechanomyography (MMG) is the epidermal measurement of the low-frequency vibrations produced by a contracting muscle. MMG sensors do not have to be in direct contact with the skin. Moreover, the embedding of sensors in the roll-on sleeve may also solve attachment issues, making sensor placement flexible. Therefore the objective was to determine the feasibility of recording MMG signals using silicon-embedded, micro-machined accelerometers. Fifteen embedded accelerometers were excited with predefined vibration patterns. The signal-to-noise ratio (SNR) and frequency response of each sample were measured and compared with those of non-embedded accelerometers. The SNR of embedded samples (approximately equal to 19 dB) was significantly higher than that of non-embedded samples (approximately equal to 12 dB), owing to the considerable mechanical damping effect of the silicon in the 300-900 Hz bandwidth (p=0.0028). This has implications for the application of silicon-embedded accelerometers for externally powered prosthesis control. PMID:12803293

  19. Fabricating solar cells with silicon nanoparticles

    DOEpatents

    Loscutoff, Paul; Molesa, Steve; Kim, Taeseok

    2014-09-02

    A laser contact process is employed to form contact holes to emitters of a solar cell. Doped silicon nanoparticles are formed over a substrate of the solar cell. The surface of individual or clusters of silicon nanoparticles is coated with a nanoparticle passivation film. Contact holes to emitters of the solar cell are formed by impinging a laser beam on the passivated silicon nanoparticles. For example, the laser contact process may be a laser ablation process. In that case, the emitters may be formed by diffusing dopants from the silicon nanoparticles prior to forming the contact holes to the emitters. As another example, the laser contact process may be a laser melting process whereby portions of the silicon nanoparticles are melted to form the emitters and contact holes to the emitters.

  20. Modeling and analysis of silicon-embedded MEMS toroidal inductors

    NASA Astrophysics Data System (ADS)

    Araghchini, M.; Lang, J. H.

    2013-12-01

    This paper presents the modeling and analysis of three-dimensional silicon-embedded toroidal inductors designed for power converter applications. Special attention is given to modeling phenomena associated with the presence of silicon, namely an increase in loss and parasitic capacitance. Silicon-embedded inductors can be fabricated with silicon inside the donut-shaped toroidal core and inside the donut hole, as well as with silicon above, below and outside the inductor. It is argued here that, with the exception of the losses in the core at high doping densities, the losses in the silicon can be tolerated in many power applications, making fully-integrated silicon-embedded air-core inductors viable for power applications. An equivalent circuit model is presented for such inductors which captures the stored magnetic energy, the parasitic electric energy stored between the windings and the silicon, the loss in the toroidal windings, and the electrically- and magnetically-driven losses inside the silicon. The model developed here is verified against experimental data, and the comparison shows a good match over the frequency range of interest to power electronics applications.

  1. Ag doped silicon nitride nanocomposites for embedded plasmonics

    NASA Astrophysics Data System (ADS)

    Bayle, M.; Bonafos, C.; Benzo, P.; Benassayag, G.; Pécassou, B.; Khomenkova, L.; Gourbilleau, F.; Carles, R.

    2015-09-01

    The localized surface plasmon-polariton resonance (LSPR) of noble metal nanoparticles (NPs) is widely exploited for enhanced optical spectroscopies of molecules, nonlinear optics, photothermal therapy, photovoltaics, or more recently in plasmoelectronics and photocatalysis. The LSPR frequency depends not only of the noble metal NP material, shape, and size but also of its environment, i.e., of the embedding matrix. In this paper, Ag-NPs have been fabricated by low energy ion beam synthesis in silicon nitride (SiNx) matrices. By coupling the high refractive index of SiNx to the relevant choice of dielectric thickness in a SiNx/Si bilayer for an optimum antireflective effect, a very sharp plasmonic optical interference is obtained in mid-range of the visible spectrum (2.6 eV). The diffusion barrier property of the host SiNx matrix allows for the introduction of a high amount of Ag and the formation of a high density of Ag-NPs that nucleate during the implantation process. Under specific implantation conditions, in-plane self-organization effects are obtained in this matrix that could be the result of a metastable coarsening regime.

  2. Ag doped silicon nitride nanocomposites for embedded plasmonics

    SciTech Connect

    Bayle, M.; Bonafos, C. Benzo, P.; Benassayag, G.; Pécassou, B.; Carles, R.; Khomenkova, L.; Gourbilleau, F.

    2015-09-07

    The localized surface plasmon-polariton resonance (LSPR) of noble metal nanoparticles (NPs) is widely exploited for enhanced optical spectroscopies of molecules, nonlinear optics, photothermal therapy, photovoltaics, or more recently in plasmoelectronics and photocatalysis. The LSPR frequency depends not only of the noble metal NP material, shape, and size but also of its environment, i.e., of the embedding matrix. In this paper, Ag-NPs have been fabricated by low energy ion beam synthesis in silicon nitride (SiN{sub x}) matrices. By coupling the high refractive index of SiN{sub x} to the relevant choice of dielectric thickness in a SiN{sub x}/Si bilayer for an optimum antireflective effect, a very sharp plasmonic optical interference is obtained in mid-range of the visible spectrum (2.6 eV). The diffusion barrier property of the host SiN{sub x} matrix allows for the introduction of a high amount of Ag and the formation of a high density of Ag-NPs that nucleate during the implantation process. Under specific implantation conditions, in-plane self-organization effects are obtained in this matrix that could be the result of a metastable coarsening regime.

  3. Misfit stabilized embedded nanoparticles in metallic alloys.

    PubMed

    Gornostyrev, Yu N; Katsnelson, M I

    2015-11-01

    Nanoscale inhomogeneities are typical for numerous metallic alloys and crucially important for their practical applications. At the same time, stabilization mechanisms of such a state are poorly understood. We present a general overview of the problem, together with a more detailed discussion of the prototype example, namely, Guinier-Preston zones in Al-based alloys. It is shown that coherent strain due to a misfit between inclusion and host crystal lattices plays a decisive role in the emergence of the inhomogeneous state. We suggest a model explaining the formation of ultrathin plates (with the thickness of a few lattice constants) typical for Al-Cu alloys. Discreteness of the array of misfit dislocations and long-ranged elastic interactions between them are the key ingredients of the model. This opens a way for a general understanding of the nature of (meta)stable embedded nanoparticles in practically important systems. PMID:26431075

  4. Spectroscopic enhancement in nanoparticles embedded glasses

    NASA Astrophysics Data System (ADS)

    Sahar, M. R.; Ghoshal, S. K.

    2014-09-01

    This presentation provides an overview of the recent progress in the enhancement of the spectroscopic characteristics of the glass embedded with nanoparticles (NPs). Some of our research activities with few significantly new results are highlighted and facilely analyzed. The science and technology dealing with the manipulation of the physical properties of rare earth doped inorganic glasses by embedding metallic NPs or nanoclusters produce the so-called 'nanoglass'. Meanwhile, the spectroscopic enhancement relates the intensity of the luminescence measured at certain transition. The enhancement which expectedly due to the 'plasmonics wave' (referring to the coherent coupling of photons to free electron oscillations called plasmon) occurs at the interface between a conductor and a dielectric. Plasmonics being an emerging concept in advanced optical material of nanophotonics has given this material the ability to exploit the optical response at nanoscale and opened up a new avenue in metal-based glass optics. There is a vast array of plasmonic NPs concepts yet to be explored, with applications spanning solar cells, (bio) sensing, communications, lasers, solid-state lighting, waveguides, imaging, optical data transfer, display and even bio-medicine. Localized surface plasmon resonance (LSPR) can enhance the optical response of nanoglass by orders of magnitude as observed. The luminescence enhancement and surface enhanced Raman scattering (SERS) are new paradigm of research. The enhancement of luminescence due to the influence of metallic NPs is the recurring theme of this paper.

  5. Spectroscopic enhancement in nanoparticles embedded glasses

    SciTech Connect

    Sahar, M. R. Ghoshal, S. K.

    2014-09-25

    This presentation provides an overview of the recent progress in the enhancement of the spectroscopic characteristics of the glass embedded with nanoparticles (NPs). Some of our research activities with few significantly new results are highlighted and facilely analyzed. The science and technology dealing with the manipulation of the physical properties of rare earth doped inorganic glasses by embedding metallic NPs or nanoclusters produce the so-called 'nanoglass'. Meanwhile, the spectroscopic enhancement relates the intensity of the luminescence measured at certain transition. The enhancement which expectedly due to the 'plasmonics wave' (referring to the coherent coupling of photons to free electron oscillations called plasmon) occurs at the interface between a conductor and a dielectric. Plasmonics being an emerging concept in advanced optical material of nanophotonics has given this material the ability to exploit the optical response at nanoscale and opened up a new avenue in metal-based glass optics. There is a vast array of plasmonic NPs concepts yet to be explored, with applications spanning solar cells, (bio) sensing, communications, lasers, solid-state lighting, waveguides, imaging, optical data transfer, display and even bio-medicine. Localized surface plasmon resonance (LSPR) can enhance the optical response of nanoglass by orders of magnitude as observed. The luminescence enhancement and surface enhanced Raman scattering (SERS) are new paradigm of research. The enhancement of luminescence due to the influence of metallic NPs is the recurring theme of this paper.

  6. Photo-response of a nanopore device with a single embedded ZnO nanoparticle

    NASA Astrophysics Data System (ADS)

    Nguyen, Linh-Nam; Lin, Ming-Chou; Chen, Horng-Shyang; Lan, Yann-Wen; Wu, Cen-Shawn; Chang-Liao, Kuei-Shu; Chen, Chii-Dong

    2012-04-01

    The photo-response of a ZnO nanoparticle embedded in a nanopore made on a silicon nitride membrane is investigated. The ZnO nanoparticle is manipulated onto the nanopore and sandwiched between aluminum contact electrodes from both the top and bottom. The asymmetric device structure facilitates current-voltage rectification that enables photovoltaic capacity. Under illumination, the device shows open-circuit voltage as well as short-circuit current. The fill factor is found to increase at low temperatures and reaches 48.6% at 100 K. The nanopore structure and the manipulation technique provide a solid platform for exploring the electrical properties of single nanoparticles.

  7. Silicon-Embedding Approaches to 3-D Toroidal Inductor Fabrication

    SciTech Connect

    Yu, XH; Kim, M; Herrault, F; Ji, CH; Kim, J; Allen, MG

    2013-06-01

    This paper presents complementary-metal-oxide-semiconductor-compatible silicon-embedding techniques for on-chip integration of microelectromechanical-system devices with 3-D complex structures. By taking advantage of the "dead volume" within the bulk of the silicon wafer, functional devices with large profile can be embedded into the substrate without consuming valuable die area on the wafer surface or increasing the packaging complexity. Furthermore, through-wafer interconnects can be implemented to connect the device to the circuitry on the wafer surface. The key challenge of embedding structures within the wafer volume is processing inside deep trenches. To achieve this goal in an area-efficient manner, straight-sidewall trenches are desired, adding additional difficulty to the embedding process. Two approaches to achieve this goal are presented in this paper, i.e., a lithography-based process and a shadow-mask-based process. The lithography-based process utilizes a spray-coating technique and proximity lithography in combination with thick epoxy processing and laminated dry-film lithography. The shadow-mask-based process employs a specially designed 3-D silicon shadow mask to enable simultaneous metal patterning on both the vertical sidewall and the bottom surface of the trench during deposition, eliminating multiple lithography steps and reducing the process time. Both techniques have been demonstrated through the embedding of the topologically complex 3-D toroidal inductors into the silicon substrate for power supply on-chip (PwrSoC) applications. Embedded 3-D inductors that possess 25 turns and a diameter of 6 mm in a silicon trench of 300-mu m depth achieve overall inductances of 45-60 nH, dc resistances of 290-400 m Omega, and quality factors of 16-17.5 at 40-70 MHz.

  8. Recent Progress on the Preparation of Luminescent Silicon Nanoparticles for Bio-Imaging Applications

    NASA Astrophysics Data System (ADS)

    Maurice, V.; Sublemontier, O.; Herlin-Boime, N.; Doris, E.; Raccurt, O.; Sanson, A.

    2010-10-01

    : Luminescent silicon nanoparticles particles produced by laser pyrolysis are considered as possible alternative to replace toxic Quantum Dot in bioimaging applications. However, these nanoparticles are fully oxidized when kept in water, therefore, the luminescent silicon core must be be protected from oxidation. The Si nanoparticles were embedded in monodisperse silica beads (˜50 nm) produced in microemulsion. The silica beads provide protection of the silicon core and allow stability of the photoluminescence over time. They are well dispersed in water and biological medium with a colloidal stability of several days.

  9. Intracellular trafficking of silicon particles and logic-embedded vectors

    NASA Astrophysics Data System (ADS)

    Ferrati, Silvia; Mack, Aaron; Chiappini, Ciro; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro; Serda, Rita E.

    2010-08-01

    Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon particles to be optimized for specific applications such as vascular targeting and avoidance of biological barriers commonly found between the site of drug injection and the final destination. In this study, the intracellular trafficking of unloaded carrier silicon particles and carrier particles loaded with secondary iron oxide nanoparticles was investigated. Following cellular uptake, membrane-encapsulated silicon particles migrated to the perinuclear region of the cell by a microtubule-driven mechanism. Surface charge, shape (spherical and hemispherical) and size (1.6 and 3.2 μm) of the particle did not alter the rate of migration. Maturation of the phagosome was associated with an increase in acidity and acquisition of markers of late endosomes and lysosomes. Cellular uptake of iron oxide nanoparticle-loaded silicon particles resulted in sorting of the particles and trafficking to unique destinations. The silicon carriers remained localized in phagosomes, while the second stage iron oxide nanoparticles were sorted into multi-vesicular bodies that dissociated from the phagosome into novel membrane-bound compartments. Release of iron from the cells may represent exocytosis of iron oxide nanoparticle-loaded vesicles. These results reinforce the concept of multi-functional nanocarriers, in which different particles are able to perform specific tasks, in order to deliver single- or multi-component payloads to specific sub-cellular compartments.Mesoporous silicon particles show great promise for use in drug delivery and imaging applications as carriers for second-stage nanoparticles and higher order particles or therapeutics. Modulation of particle geometry, surface chemistry, and porosity allows silicon

  10. Optimizing Silicon Oxide Embedded Silicon Nanocrystal Inter-particle Distances.

    PubMed

    van Sebille, Martijn; Allebrandi, Jort; Quik, Jim; van Swaaij, René A C M M; Tichelaar, Frans D; Zeman, Miro

    2016-12-01

    We demonstrate an analytical method to optimize the stoichiometry and thickness of multilayer silicon oxide films in order to achieve the highest density of non-touching and closely spaced silicon nanocrystals after annealing. The probability of a nanocrystal nearest-neighbor distance within a limited range is calculated using the stoichiometry of the as-deposited film and the crystallinity of the annealed film as input parameters. Multiplying this probability with the nanocrystal density results in the density of non-touching and closely spaced silicon nanocrystals. This method can be used to estimate the best as-deposited stoichiometry in order to achieve optimal nanocrystal density and spacing after a subsequent annealing step. PMID:27492439

  11. Optimizing Silicon Oxide Embedded Silicon Nanocrystal Inter-particle Distances

    NASA Astrophysics Data System (ADS)

    van Sebille, Martijn; Allebrandi, Jort; Quik, Jim; van Swaaij, René A. C. M. M.; Tichelaar, Frans D.; Zeman, Miro

    2016-08-01

    We demonstrate an analytical method to optimize the stoichiometry and thickness of multilayer silicon oxide films in order to achieve the highest density of non-touching and closely spaced silicon nanocrystals after annealing. The probability of a nanocrystal nearest-neighbor distance within a limited range is calculated using the stoichiometry of the as-deposited film and the crystallinity of the annealed film as input parameters. Multiplying this probability with the nanocrystal density results in the density of non-touching and closely spaced silicon nanocrystals. This method can be used to estimate the best as-deposited stoichiometry in order to achieve optimal nanocrystal density and spacing after a subsequent annealing step.

  12. Plasmonic and silicon spherical nanoparticle antireflective coatings

    PubMed Central

    Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

    2016-01-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

  13. Plasmonic and silicon spherical nanoparticle antireflective coatings

    NASA Astrophysics Data System (ADS)

    Baryshnikova, K. V.; Petrov, M. I.; Babicheva, V. E.; Belov, P. A.

    2016-03-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes.

  14. Plasmonic and silicon spherical nanoparticle antireflective coatings.

    PubMed

    Baryshnikova, K V; Petrov, M I; Babicheva, V E; Belov, P A

    2016-01-01

    Over the last decade, plasmonic antireflecting nanostructures have been extensively studied to be utilized in various optical and optoelectronic systems such as lenses, solar cells, photodetectors, and others. The growing interest to all-dielectric photonics as an alternative optical technology along with plasmonics motivates us to compare antireflective properties of plasmonic and all-dielectric nanoparticle coatings based on silver and crystalline silicon respectively. Our simulation results for spherical nanoparticles array on top of amorphous silicon show that both silicon and silver coatings demonstrate strong antireflective properties in the visible spectral range. For the first time, we show that zero reflectance from the structure with silicon coatings originates from the destructive interference of electric- and magnetic-dipole responses of nanoparticle array with the wave reflected from the substrate, and we refer to this reflection suppression as substrate-mediated Kerker effect. We theoretically compare the silicon and silver coating effectiveness for the thin-film photovoltaic applications. Silver nanoparticles can be more efficient, enabling up to 30% increase of the overall absorbance in semiconductor layer. Nevertheless, silicon coatings allow up to 64% absorbance increase in the narrow band spectral range because of the substrate-mediated Kerker effect, and band position can be effectively tuned by varying the nanoparticles sizes. PMID:26926602

  15. LOGIC-EMBEDDED VECTORS FOR INTRACELLULAR PARTITIONING, ENDOSOMAL ESCAPE, AND EXOCYTOSIS OF NANOPARTICLES

    PubMed Central

    Serda, Rita E.; Mack, Aaron; van de Ven, Anne; Ferrati, Silvia; Dunner, Kenneth; Godin, Biana; Chiappini, Ciro; Landry, Matthew; Brousseau, Lou; Liu, Xuewu; Bean, Andrew J.; Ferrari, Mauro

    2010-01-01

    A new generation of nanocarriers, logic-embedded vectors (LEVs), is endowed with the ability to localize components at multiple intracellular sites, creating an opportunity for synergistic control of redundant or dual-hit pathways. LEV encoding elements include size, shape, charge, and surface chemistry. In this study, LEVs consist of porous silicon nanocarriers, programmed for cellular uptake and trafficking along the endosomal pathway, and surface-tailored iron oxide nanoparticles, programmed for endosomal sorting and partitioning of particles into unique cellular locations. In the presence of persistent endosomal localization of silicon nanocarriers, amine-functionalized nanoparticles are sorted into multiple vesicular bodies that form novel membrane-bound compartments compatible with cellular secretion, while chitosan-coated nanoparticles escape from endosomes and enter the cytosol. Encapsulation within the porous silicon matrix protects these nanoparticle surface tailored-properties, enhancing endosomal escape of chitosan coated nanoparticles. Thus LEVs provide a mechanism for shielded transport of nanoparticles to the lesion, cellular manipulation at multiple levels, and a means for targeting both within and between cells. PMID:20957619

  16. Silicon-embedded copper nanostructure network for high energy storage

    DOEpatents

    Yu, Tianyue

    2016-03-15

    Provided herein are nanostructure networks having high energy storage, electrochemically active electrode materials including nanostructure networks having high energy storage, as well as electrodes and batteries including the nanostructure networks having high energy storage. According to various implementations, the nanostructure networks have high energy density as well as long cycle life. In some implementations, the nanostructure networks include a conductive network embedded with electrochemically active material. In some implementations, silicon is used as the electrochemically active material. The conductive network may be a metal network such as a copper nanostructure network. Methods of manufacturing the nanostructure networks and electrodes are provided. In some implementations, metal nanostructures can be synthesized in a solution that contains silicon powder to make a composite network structure that contains both. The metal nanostructure growth can nucleate in solution and on silicon nanostructure surfaces.

  17. Multi-band silicon quantum dots embedded in an amorphous matrix of silicon carbide.

    PubMed

    Chang, Geng-rong; Ma, Fei; Ma, Da-yan; Xu, Ke-wei

    2010-11-19

    Silicon quantum dots embedded in an amorphous matrix of silicon carbide were realized by a magnetron co-sputtering process and post-annealing. X-ray photoelectron spectroscopy, glancing x-ray diffraction, Raman spectroscopy and high-resolution transmission electron microscopy were used to characterize the chemical composition and the microstructural properties. The results show that the sizes and size distribution of silicon quantum dots can be tuned by changing the annealing atmosphere and the atom ratio of silicon and carbon in the matrix. A physicochemical mechanism is proposed to demonstrate this formation process. Photoluminescence measurements indicate a multi-band configuration due to the quantum confinement effect of silicon quantum dots with different sizes. The PL spectra are further widened as a result of the existence of amorphous silicon quantum dots. This multi-band configuration would be extremely advantageous in improving the photoelectric conversion efficiency of photovoltaic solar cells. PMID:20975214

  18. Functionalised silicon oxide nanoparticles for fingermark detection.

    PubMed

    Moret, Sébastien; Bécue, Andy; Champod, Christophe

    2016-02-01

    Over the past decade, the use of nanotechnology for fingermark detection has been attracting a lot of attention. A substantial number of nanoparticle types has thus been studied and applied with varying success. However, despite all efforts, few publications present clear supporting evidence of their superiority over standard and commonly used techniques. This paper focuses on a rarely studied type of nanoparticles that regroups all desired properties for effective fingermark detection: silicon oxide. These nanoparticles offer optical and surface properties that can be tuned to provide optimal detection. This study explores their potential as a new method for fingermark detection. Detection conditions, outer functionalisations and optical properties were optimised and a first evaluation of the technique is presented. Dye-doped silicon oxide nanoparticles were assessed against a one-step luminescent cyanoacrylate. Both techniques were compared on natural fingermarks from three donors collected on four different non-porous substrates. On average, the two techniques performed similarly but silicon oxide detected marks with a better homogeneity and was less affected by donor inter-variability. The technique remains to be further optimised and yet silicon oxide nanoparticles already show great promises for effective fingermark detection. PMID:26717406

  19. Gas phase synthesis of two ensembles of silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohan, A.; de Jong, M. M.; Poulios, I.; Schropp, R. E. I.; Rath, J. K.

    2015-09-01

    Dusty plasmas provide a very favorable environment for the growth of silicon nanocrystals. For application of silicon nanocrystals in a solar cell, the fabrication of monodisperse silicon quantum dots has been challenging. We report a single step method to synthesize silicon (Si) nanoparticles in a custom designed dedicated plasma reactor. The nanoparticles produced in the gas phase belong to two different phases exhibiting different structural and optical properties. Particles made in the bulk of the plasma are aggregates of crystalline particles with a mean size of 100 nm. Particles made in locally enhanced plasma regions produced at holes present in the grounded electrode contain free-standing quantum sized particles with crystallites (with mean size of 2.95 nm) embedded within an amorphous matrix. We provide insight on different plasma processes leading to the formation of aggregates and free-standing particles. We hypothesize that the free standing particles are formed due to the excess energetic electrons present in locally enhanced discharges.

  20. Structural characterization of copolymer embedded magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Nedelcu, G. G.; Nastro, A.; Filippelli, L.; Cazacu, M.; Iacob, M.; Rossi, C. Oliviero; Popa, A.; Toloman, D.; Dobromir, M.; Iacomi, F.

    2015-10-01

    Small magnetic nanoparticles (Fe3O4) were synthesized by co-precipitation and coated by emulsion polymerization with poly(methyl methacrylate-co-acrylic acid) (PMMA-co-AAc) to create surface functional groups that can attach drug molecules and other biomolecules. The coated and uncoated magnetite nanoparticles were stored for two years in normal closed ships and than characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and electron paramagnetic resonance spectroscopy. The solid phase transformation of magnetite to maghemite, as well as an increase in particle size were evidenced for the uncoated nanoparticles. The coated nanoparticles preserved their magnetite structure and magnetic properties. The influences of monomers and surfactant layers on interactions between the magnetic nanoparticles evidenced that the thickness of the polymer has a significant effect on magnetic properties.

  1. Photo-response of a nanopore device with a single embedded ZnO nanoparticle.

    PubMed

    Nguyen, Linh-Nam; Lin, Ming-Chou; Chen, Horng-Shyang; Lan, Yann-Wen; Wu, Cen-Shawn; Chang-Liao, Kuei-Shu; Chen, Chii-Dong

    2012-04-01

    The photo-response of a ZnO nanoparticle embedded in a nanopore made on a silicon nitride membrane is investigated. The ZnO nanoparticle is manipulated onto the nanopore and sandwiched between aluminum contact electrodes from both the top and bottom. The asymmetric device structure facilitates current-voltage rectification that enables photovoltaic capacity. Under illumination, the device shows open-circuit voltage as well as short-circuit current. The fill factor is found to increase at low temperatures and reaches 48.6% at 100 K. The nanopore structure and the manipulation technique provide a solid platform for exploring the electrical properties of single nanoparticles. PMID:22470086

  2. Structure and magnetism in Cr-embedded Co nanoparticles

    NASA Astrophysics Data System (ADS)

    Baker, S. H.; Kurt, M. S.; Roy, M.; Lees, M. R.; Binns, C.

    2016-02-01

    We present the results of an investigation into the atomic structure and magnetism of 2 nm diameter Co nanoparticles embedded in an antiferromagnetic Cr matrix. The nanocomposite films used in this study were prepared by co-deposition directly from the gas phase, using a gas aggregation source for the Co nanoparticles and a molecular beam epitaxy (MBE) source for the Cr matrix material. Co K and Cr K edge extended x-ray absorption fine structure (EXAFS) experiments were performed in order to investigate atomic structure in the embedded nanoparticles and matrix respectively, while magnetism was investigated by means of a vibrating sample magnetometer. The atomic structure type of the Co nanoparticles is the same as that of the Cr matrix (bcc) although with a degree of disorder. The net Co moment per atom in the Co/Cr nanocomposite films is significantly reduced from the value for bulk Co, and decreases as the proportion of Co nanoparticles in the film is decreased; for the sample with the most dilute concentration of Co nanoparticles (4.9% by volume), the net Co moment was 0.25 μ B/atom. After field cooling to below 30 K all samples showed an exchange bias, which was largest for the most dilute sample. Both the structural and magnetic results point towards a degree of alloying at the nanoparticle/matrix interface, leading to a core/shell structure in the embedded nanoparticles consisting of an antiferromagnetic CoCr alloy shell surrounding a reduced ferromagnetic Co core.

  3. Structure and magnetism in Cr-embedded Co nanoparticles.

    PubMed

    Baker, S H; Kurt, M S; Roy, M; Lees, M R; Binns, C

    2016-02-01

    We present the results of an investigation into the atomic structure and magnetism of 2 nm diameter Co nanoparticles embedded in an antiferromagnetic Cr matrix. The nanocomposite films used in this study were prepared by co-deposition directly from the gas phase, using a gas aggregation source for the Co nanoparticles and a molecular beam epitaxy (MBE) source for the Cr matrix material. Co K and Cr K edge extended x-ray absorption fine structure (EXAFS) experiments were performed in order to investigate atomic structure in the embedded nanoparticles and matrix respectively, while magnetism was investigated by means of a vibrating sample magnetometer. The atomic structure type of the Co nanoparticles is the same as that of the Cr matrix (bcc) although with a degree of disorder. The net Co moment per atom in the Co/Cr nanocomposite films is significantly reduced from the value for bulk Co, and decreases as the proportion of Co nanoparticles in the film is decreased; for the sample with the most dilute concentration of Co nanoparticles (4.9% by volume), the net Co moment was 0.25 μ B/atom. After field cooling to below 30 K all samples showed an exchange bias, which was largest for the most dilute sample. Both the structural and magnetic results point towards a degree of alloying at the nanoparticle/matrix interface, leading to a core/shell structure in the embedded nanoparticles consisting of an antiferromagnetic CoCr alloy shell surrounding a reduced ferromagnetic Co core. PMID:26740510

  4. Nanoparticle embedded enzymes for improved lateral flow sensors.

    PubMed

    Özalp, Veli C; Zeydanlı, Uğur S; Lunding, Anita; Kavruk, Murat; Öz, M Tufan; Eyidoğan, Füsun; Olsen, Lars F; Öktem, Hüseyin A

    2013-08-01

    In this study, combining the nanoparticle embedded sensors with lateral flow assays, a novel strategy for ensuring the quality of signalling in lateral flow assays (LFAs) was developed. A LFA for reactive oxygen species (ROS) is reported that is based on horse radish peroxidase (HRP) which is co-entrapped with Texas Red dextran inside porous polyacrylamide nanoparticles. In this system, enzymes are protected in the porous matrix of polyacrylamide which freely allows the diffusion of the analyte. The sensor is rapid and sensitive for quantification of hydrogen peroxide concentrations. A test solution of hydrogen peroxides was quantified with this novel LFA-ROS sensor to obtain a linear range between 1 and 25 μM. Nanoparticle embedding of enzymes is proposed here as a general strategy for developing enzyme-based lateral flow assays, eliminating adverse effects associated with biological samples. PMID:23730687

  5. Gated Luminescence Imaging of Silicon Nanoparticles

    PubMed Central

    Joo, Jinmyoung; Liu, Xiangyou; Kotamraju, Venkata Ramana; Ruoslahti, Erkki; Nam, Yoonkey; Sailor, Michael J.

    2016-01-01

    The luminescence lifetime of nanocrystalline silicon is typically on the order of microseconds, significantly longer than the nanosecond lifetimes exhibited by fluorescent molecules naturally present in cells and tissues. Time-gated imaging, where the image is acquired at a time after termination of an excitation pulse, allows discrimination of a silicon nanoparticle probe from these endogenous signals. Because of the microsecond time scale for silicon emission, time-gated imaging is relatively simple to implement for this biocompatible and nontoxic probe. Here a time-gated system with ~10 ns resolution is described, using an intensified CCD camera and pulsed LED or laser excitation sources. The method is demonstrated by tracking the fate of mesoporous silicon nanoparticles containing the tumor-targeting peptide iRGD, administered by retro-orbital injection into live mice. Imaging of such systemically administered nanoparticles in vivo is particularly challenging because of the low concentration of probe in the targeted tissues and relatively high background signals from tissue autofluorescence. Contrast improvements of >100-fold (relative to steady-state imaging) is demonstrated in the targeted tissues. PMID:26034817

  6. Embedded strain gauges for condition monitoring of silicone gaskets.

    PubMed

    Schotzko, Timo; Lang, Walter

    2014-01-01

    A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term. PMID:25014099

  7. Embedded Strain Gauges for Condition Monitoring of Silicone Gaskets

    PubMed Central

    Schotzko, Timo; Lang, Walter

    2014-01-01

    A miniaturized strain gauge with a thickness of 5 µm is molded into a silicone O-ring. This is a first step toward embedding sensors in gaskets for structural health monitoring. The signal of the integrated sensor exhibits a linear correlation with the contact pressure of the O-ring. This affords the opportunity to monitor the gasket condition during installation. Thus, damages caused by faulty assembly can be detected instantly, and early failures, with their associated consequences, can be prevented. Through the embedded strain gauge, the contact pressure applied to the gasket can be directly measured. Excessive pressure and incorrect positioning of the gasket can cause structural damage to the material of the gasket, which can lead to an early outage. A platinum strain gauge is fabricated on a thin polyimide layer and is contacted through gold connections. The measured resistance pressure response exhibits hysteresis for the first few strain cycles, followed by a linear behavior. The short-term impact of the embedded sensor on the stability of the gasket is investigated. Pull-tests with O-rings and test specimens have indicated that the integration of the miniaturized sensors has no negative impact on the stability in the short term. PMID:25014099

  8. Optical Properties of Free and Embedded Small Nanoparticles

    NASA Astrophysics Data System (ADS)

    Idrobo, Juan

    2008-03-01

    It is well known that the absorption spectra, as well as the effective dielectric function, of nanoparticles in vacuum or surrounded by a dielectric medium can be obtained by classical Mie and Maxwell-Garnett theories. A limit as to how the particles can be for the theory to apply has not been established. Here I present theoretical results on the optical properties of small Ag, Au, and Si and Ge nanoparticles with tens of atoms in vacuum and in an embedded dielectric medium obtained from first-principles density-functional calculations. In particular, I will discuss the role that d-electron play on the optical properties of Ag and Au nanoparticles, and the cases when classical Mie and Maxwell-Garnett theories can be applied for nanoparticles of just few atoms in size and whose atoms are in bulk-like and not bulk-like positions. Comparison will be made for nanoparticles in vacuum and embedded in an alumina matrix. The quantum-mechanical results indicate that small nanoparticles in alumina can have an imprint on the effective dielectric function that is several times larger than would be predicted by Maxwell-Garnett theory for same-size particles. This work was supported by a GOALI NSF grant, DOE, the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, and Alcoa Inc. Collaborators: S. ögüt, K. Jackson, J. Jellinek, A. Halabica. R. F. Haglund, R. Magruder, S.J. Pennycook and S.T. Pantelides.

  9. Photoluminescence mechanism model for oxidized porous silicon and nanoscale-silicon-particle-embedded silicon oxide

    NASA Astrophysics Data System (ADS)

    Qin, G. G.; Li, Y. J.

    2003-08-01

    There is much debate about the photoluminescence (PL) mechanisms of the nanoscale Si/Si oxide systems containing oxidized porous silicon and a nanoscale-Si-particle (NSP)—embedded Si oxide deposited by chemical vapor deposition, sputtering, or Si-ion implanting into Si oxide. In this paper, we suggest that two competitive processes, namely, the quantum confinement (QC) process and the quantum confinement-luminescence center (QCLC) process, take place in the PL. The photoexcitation occurs in the NSPs for both of the processes, while the photoemission occurs either in the NSPs for the QC process or in the luminescence centers (LCs) in Si oxide adjacent to the NSPs for the QCLC process. The rates of the two processes are compared quantitatively. Which process plays the major role in PL is determined by the capture cross section, the luminescence efficiency, and the density of the LCs, and the sizes of the NSPs. For a nanoscale Si/Si oxide system with the LCs having certain capture cross-section and luminescence efficiency, the higher the LC density and the larger the sizes of NSPs, the more beneficial for the QCLC process to surpass the QC process, and vice versa. For certain LC parameters, there is a critical most probable size for the NSPs. When the most probable size of the NSPs is larger than the critical one, the QCLC process dominates the PL, and when the most probable size of the NSPs is smaller than the critical one, the QC process dominates the PL. When the most probable size of the NSPs is close to the critical one, both the QC and QCLC processes should be taken into account. We have used this model to discuss PL experimental results reported for some nanoscale Si/Si oxide systems.

  10. Experimental measurement of plasmonic nanostructures embedded in silicon waveguide gaps.

    PubMed

    Espinosa-Soria, Alba; Griol, Amadeu; Martínez, Alejandro

    2016-05-01

    In this work, we report numerical simulations and experiments of the optical response of a gold nanostrip embedded in a silicon strip waveguide gap at telecom wavelengths. We show that the spectral features observed in transmission and reflection when the metallic nanostructure is inserted in the gap are extremely different than those observed in free-space excitation. First, we find that interference between the guided field and the electric dipolar resonance of the metallic nanostructure results in high-contrast (> 10) spectral features showing an asymmetric Fano spectral profile. Secondly, we reveal a crossing in the transmission and reflection responses close to the nanostructure resonance wavelength as a key feature of our system. This approach, which can be realized using standard semiconductor nanofabrication tools, could lead to a full exploitation of the extreme properties of subwavelength metallic nanostructures in an on-chip configuration, with special relevance in fields such as biosensing or optical switching. PMID:27137572

  11. Nanoparticle-based etching of silicon surfaces

    SciTech Connect

    Branz, Howard; Duda, Anna; Ginley, David S.; Yost, Vernon; Meier, Daniel; Ward, James S.

    2011-12-13

    A method (300) of texturing silicon surfaces (116) such to reduce reflectivity of a silicon wafer (110) for use in solar cells. The method (300) includes filling (330, 340) a vessel (122) with a volume of an etching solution (124) so as to cover the silicon surface 116) of a wafer or substrate (112). The etching solution (124) is made up of a catalytic nanomaterial (140) and an oxidant-etchant solution (146). The catalytic nanomaterial (140) may include gold or silver nanoparticles or noble metal nanoparticles, each of which may be a colloidal solution. The oxidant-etchant solution (146) includes an etching agent (142), such as hydrofluoric acid, and an oxidizing agent (144), such as hydrogen peroxide. Etching (350) is performed for a period of time including agitating or stirring the etching solution (124). The etch time may be selected such that the etched silicon surface (116) has a reflectivity of less than about 15 percent such as 1 to 10 percent in a 350 to 1000 nanometer wavelength range.

  12. A novel recovery of silicon nanoparticles from a waste silicon sludge.

    PubMed

    Jang, Hee Dong; Kim, Hyekyoung; Kil, Dae Sup; Chang, Hankwon

    2013-03-01

    As the semiconductor and photovoltaic industry undergo rapid growth, a large amount of silicon sludge is generated from the cutting process of silicon ingots. However, it is not effectively recycled. Recovery of nanometer-sized silicon (Si) particles from the sludge has become an important concern because the silicon sludge contains valuable resources including high purity silicon. In the present study, we investigated the novel recovery of Si nanoparticles from waste silicon sludge. The waste silicon sludge also contained surfactant, silicon carbide particles and metallic fragments. After removal of the surfactant by distillation, the Si nanoparticles were recovered by applying controlled ultrasonic waves and centrifugation in series. Metallic impurities in the recovered Si nanoparticles were purified by HCl treatment. The overall maximum yield and purity of the Si nanoparticles were about 80% and 99.7%, respectively. PMID:23755688

  13. Nanocrystalline silicon embedded in silicon suboxide synthesized in high-density inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhou, H. P.; Xu, S.; Xu, M.; Xiao, S. Q.; Xiang, Y.

    2015-11-01

    A two-phase material system of nanocrystalline silicon (nc-Si) embedded in a dielectric matrix of silicon suboxide (SiO x ) is fundamentally and technologically significant for the photonic and photovoltaic device such as light emission diode and solar cells. nc-Si in amorphous SiO x has been synthesized by means of the low-frequency (460 kHz) inductively coupled plasma (LFICP) of SiH4  +  CO2  +  H2 without the common route of high hydrogen dilution. The chemical composition, microstructures and optical properties of the complex material system are tuned by the reactive gas flow rate ratio of CO2/SiH4. nc-Si embedded in amorphous SiO x due to the phase separation are observed by means of SEM and TEM characterization tools. The crystalline volume fraction in nc-SiO x :H is determined by the density of the embedded nc-Si particles and the occurrence of the a-SiO x encapsulating shell layer. The bond configuration analysis shows the concurrent oxygenation and dehydrogenation process with the incorporation of oxygen. The underlying mechanism in forming the two-phase complex material system and the phase evolution with the reactive gas flow rate ratio are discussed in terms of the unique features of the utilized high-density LFICP.

  14. Photoluminescence decay rate of silicon nanoparticles modified with gold nanoislands

    PubMed Central

    2014-01-01

    We investigated plasmon-assisted enhancement of emission from silicon nanoparticles (ncs-Si) embedded into porous SiO x matrix in the 500- to 820-nm wavelength range. In the presence in the near-surface region of gold nanoisland film, ncs-Si exhibited up to twofold luminescence enhancement at emission frequencies that correspond to the plasmon resonance frequency of Au nanoparticles. Enhancement of the photoluminescence (PL) intensity was attributed to coupling with the localized surface plasmons (LSPs) excited in Au nanoparticles and to increase in the radiative decay rate of ncs-Si. It has been shown that spontaneous emission decay rate of ncs-Si modified by thin Au film over the wide emission spectral range was accelerated. The emission decay rate distribution was determined by fitting the experimental decay curves to the stretched exponential model. The observed increase of the PL decay rate distribution width for the Au-coated nc-Si-SiO x sample in comparison with the uncoated one was explained by fluctuations in the surface-plasmon excitation rate. PACS 78. 67. Bf; 78.55.-m PMID:24708532

  15. The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles.

    PubMed

    Granitzer, P; Rumpf, K; Gonzalez-Rodriguez, R; Coffer, J L; Reissner, M

    2015-12-21

    The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay with the iron oxide nanoparticle size, plays a sensitive role. It is shown that Fe3O4 loaded porous silicon and SiNTs differ significantly in their magnetic behavior, especially the transition between superparamagnetic behavior and blocked state, due to host morphology-dependent magnetic interactions. Importantly, it is found that all investigated samples meet the magnetic precondition of possible biomedical applications of exhibiting a negligible magnetic remanence at room temperature. PMID:26575478

  16. Modeling pulsed-laser melting of embedded semiconductor nanoparticles

    SciTech Connect

    Sawyer, C.A.; Guzman, J.; Boswell-Koller, C.N.; Sherburne, M.P.; Mastandrea, J.P.; Bustillo, K.C.; Ager III, J.W.; Haller, E.E.; Chrzan, D.C.

    2011-05-18

    Pulsed-laser melting (PLM) is commonly used to achieve a fast quench rate in both thin films and nanoparticles. A model for the size evolution during PLM of nanoparticles confined in a transparent matrix, such as those created by ion-beam synthesis, is presented. A self-consistent mean-field rate equations approach that has been used successfully to model ion beam synthesis of germanium nanoparticles in silica is extended to include the PLM process. The PLM model includes classical optical absorption, multiscale heat transport by both analytical and finite difference methods, and melting kinetics for confined nanoparticles. The treatment of nucleation and coarsening behavior developed for the ion beam synthesis model is modified to allow for a non-uniform temperature gradient and for interacting liquid and solid particles with different properties. The model allows prediction of the particle size distribution after PLM under various laser fluences, starting from any particle size distribution including as-implanted or annealed simulated samples. A route for narrowing the size distribution of embedded nanoparticles is suggested, with simulated distribution widths as low as 15% of the average size.

  17. Preparation and thermal stability of silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Wang, H.; Ong, P. P.

    2001-02-01

    Silicon nanoparticles were prepared in a homemade apparatus by means of a dc sputtering method in which the condensates were collected directly from the cold surface of a liquid nitrogen trap. They were dispersed in 2-propanol under ultrasonic agitation, and dried in the atmosphere. The particles were found to compose of tiny silicon crystals and were only mildly oxidized. Various samples were prepared with different annealing times and temperatures in ultrahigh vacuum. XPS results show that, in the particles, the Si-O bonds of the Si 4+ state are the most stable, followed next by the unoxidised state Si 0. The intermediate oxidation states are the least stable; they exist only at sufficiently low temperatures (300°C or lower) and are converted to either Si 0 or Si 4+ at higher temperatures.

  18. Nitric oxide-releasing porous silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Kafshgari, Morteza Hasanzadeh; Cavallaro, Alex; Delalat, Bahman; Harding, Frances J.; McInnes, Steven JP; Mäkilä, Ermei; Salonen, Jarno; Vasilev, Krasimir; Voelcker, Nicolas H.

    2014-07-01

    In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment.

  19. Nitric oxide-releasing porous silicon nanoparticles

    PubMed Central

    2014-01-01

    In this study, the ability of porous silicon nanoparticles (PSi NPs) to entrap and deliver nitric oxide (NO) as an effective antibacterial agent is tested against different Gram-positive and Gram-negative bacteria. NO was entrapped inside PSi NPs functionalized by means of the thermal hydrocarbonization (THC) process. Subsequent reduction of nitrite in the presence of d-glucose led to the production of large NO payloads without reducing the biocompatibility of the PSi NPs with mammalian cells. The resulting PSi NPs demonstrated sustained release of NO and showed remarkable antibacterial efficiency and anti-biofilm-forming properties. These results will set the stage to develop antimicrobial nanoparticle formulations for applications in chronic wound treatment. PMID:25114633

  20. Antimicrobial activity of bone cements embedded with organic nanoparticles

    PubMed Central

    Perni, Stefano; Thenault, Victorien; Abdo, Pauline; Margulis, Katrin; Magdassi, Shlomo; Prokopovich, Polina

    2015-01-01

    Infections after orthopedic surgery are a very unwelcome outcome; despite the widespread use of antibiotics, their incidence can be as high as 10%. This risk is likely to increase as antibiotics are gradually losing efficacy as a result of bacterial resistance; therefore, novel antimicrobial approaches are required. Parabens are a class of compounds whose antimicrobial activity is employed in many cosmetic and pharmaceutical products. We developed propylparaben nanoparticles that are hydrophilic, thus expanding the applicability of parabens to aqueous systems. In this paper we assess the possibility of employing paraben nanoparticles as antimicrobial compound in bone cements. The nanoparticles were embedded in various types of bone cement (poly(methyl methacrylate) [PMMA], hydroxyapatite, and brushite) and the antimicrobial activity was determined against common causes of postorthopedic surgery infections such as: Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, and Acinetobacter baumannii. Nanoparticles at concentrations as low as 1% w/w in brushite bone cement were capable of preventing pathogens growth, 5% w/w was needed for hydroxyapatite bone cement, while 7% w/w was required for PMMA bone cement. No detrimental effect was determined by the addition of paraben nanoparticles on bone cement compression strength and cytocompatibility. Our results demonstrate that paraben nanoparticles can be encapsulated in bone cement, providing concentration-dependent antimicrobial activity; furthermore, lower concentrations are needed in calcium phosphate (brushite and hydroxyapatite) than in acrylic (PMMA) bone cements. These nanoparticles are effective against a wide spectrum of bacteria, including those already resistant to the antibiotics routinely employed in orthopedic applications, such as gentamicin. PMID:26487803

  1. Porous silicon nanoparticles for target drag delivery: structure and morphology

    NASA Astrophysics Data System (ADS)

    Spivak, Yu M.; Belorus, A. O.; Somov, P. A.; Tulenin, S. S.; Bespalova, K. A.; Moshnikov, V. A.

    2015-11-01

    Nanoparticles of porous silicon were obtained by electrochemical anodic etching. Morphology and structure of the particles was investigated by means dynamic light scattering and scanning electron microscopy. The influence of technological conditions of preparation on geometrical parameters of the porous silicon particles (particle size distribution, pore shape and size, the specific surface area of the porous silicon) is discussed.

  2. Membrane deformation controlled by monolayer composition of embedded amphiphilic nanoparticles

    NASA Astrophysics Data System (ADS)

    van Lehn, Reid; Alexander-Katz, Alfredo

    2014-03-01

    In recent work, we have shown that charged, amphiphilic nanoparticles (NPs) can spontaneously insert into lipid bilayers, embedding the NP in a conformation resembling a transmembrane protein. Many embedded membrane proteins exert an influence on surrounding lipids that lead to deformation and membrane-mediated interactions that may be essential for function. Similarly, embedded NPs will also induce membrane deformations related to the same physicochemical forces. Unlike many transmembrane proteins, however, the highly charged NPs may exert preferential interactions on surrounding lipid head groups. In this work, we use atomistic molecular dynamics simulations to show that the membrane around embedded particles may experience local thinning, head group reorientation, and an increase in lipid density depending on the size and surface composition of the NP. We quantify the extent of these deformations and illustrate the complex interplay between lipid tail group and head group interactions that go beyond pure thickness deformations that may be expected from coarse-grained or continuum models. This work thus suggests guidelines for the design of particles that spontaneously partition into lipid bilayers and influence local membrane mechanical properties in a targeted manner.

  3. Effect of embedded metal compound on porosity of silica colloids prepared by spray reaction of silicon tetrachloride.

    PubMed

    Isobe, Hiroshi; Hattori, Yoshiyuki; Hayano, Tomoe; Kanoh, Hirofumi; Yamamoto, Kohzoh; Kaneko, Katsumi

    2006-03-15

    Attempts to prepare macroporous silica particles and metal-compound-nanoparticle-embedded silica microspheres were carried out using reactions between silicon tetrachloride and ultrasonic generating microdroplets including metal (Na, K, Al, Ni, Ti, Pt) compounds. Samples were collected by dry and wet processes. In the case of using nickel and aluminum compounds, acid-treated samples were also prepared. The obtained samples were characterized by scanning electron microscopy, X-ray fluorescence spectroscopy, powder X-ray diffractometry, mercury porosimetry, and the nitrogen adsorption method. The macroporous silica particles were prepared by removing the salt crystals, such as NaCl and KCl, formed in the silica frame. For acid-resistant metals, platinum- and titanium-compound nanoparticles are easily embedded in silica microspheres using these metal-compound solutions. For acid-soluble metals, aluminum- and nickel-compound-nanoparticle-embedded silicas were prepared by applying neutralization of the collection water. Micropores and mesopores were produced in wet-process samples. Acid treatment induced the increase of micropore volumes. PMID:16246356

  4. Charging/discharging behavior and mechanism of silicon quantum dots embedded in amorphous silicon carbide films

    NASA Astrophysics Data System (ADS)

    Wen, Xixing; Zeng, Xiangbin; Zheng, Wenjun; Liao, Wugang; Feng, Feng

    2015-01-01

    The charging/discharging behavior of Si quantum dots (QDs) embedded in amorphous silicon carbide (a-SiCx) was investigated based on the Al/insulating layer/Si QDs embedded in a-SiCx/SiO2/p-Si (metal-insulator-quantum dots-oxide-silicon) multilayer structure by capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Transmission electron microscopy and Raman scattering spectroscopy measurements reveal the microstructure and distribution of Si QDs. The occurrence and shift of conductance peaks indicate the carrier transfer and the charging/discharging behavior of Si QDs. The multilayer structure shows a large memory window of 5.2 eV at ±8 V sweeping voltage. Analysis of the C-V and G-V results allows a quantification of the Coulomb charging energy and the trapped charge density associated with the charging/discharging behavior. It is found that the memory window is related to the size effect, and Si QDs with large size or low Coulomb charging energy can trap two or more electrons by changing the charging voltage. Meanwhile, the estimated lower potential barrier height between Si QD and a-SiCx, and the lower Coulomb charging energy of Si QDs could enhance the charging and discharging effect of Si QDs and lead to an enlarged memory window. Further studies of the charging/discharging mechanism of Si QDs embedded in a-SiCx can promote the application of Si QDs in low-power consumption semiconductor memory devices.

  5. Charging/discharging behavior and mechanism of silicon quantum dots embedded in amorphous silicon carbide films

    SciTech Connect

    Wen, Xixing; Zeng, Xiangbin Zheng, Wenjun; Liao, Wugang; Feng, Feng

    2015-01-14

    The charging/discharging behavior of Si quantum dots (QDs) embedded in amorphous silicon carbide (a-SiC{sub x}) was investigated based on the Al/insulating layer/Si QDs embedded in a-SiC{sub x}/SiO{sub 2}/p-Si (metal-insulator-quantum dots-oxide-silicon) multilayer structure by capacitance-voltage (C-V) and conductance-voltage (G-V) measurements. Transmission electron microscopy and Raman scattering spectroscopy measurements reveal the microstructure and distribution of Si QDs. The occurrence and shift of conductance peaks indicate the carrier transfer and the charging/discharging behavior of Si QDs. The multilayer structure shows a large memory window of 5.2 eV at ±8 V sweeping voltage. Analysis of the C-V and G-V results allows a quantification of the Coulomb charging energy and the trapped charge density associated with the charging/discharging behavior. It is found that the memory window is related to the size effect, and Si QDs with large size or low Coulomb charging energy can trap two or more electrons by changing the charging voltage. Meanwhile, the estimated lower potential barrier height between Si QD and a-SiC{sub x}, and the lower Coulomb charging energy of Si QDs could enhance the charging and discharging effect of Si QDs and lead to an enlarged memory window. Further studies of the charging/discharging mechanism of Si QDs embedded in a-SiC{sub x} can promote the application of Si QDs in low-power consumption semiconductor memory devices.

  6. Optical absorption and photoluminescence studies of gold nanoparticles deposited on porous silicon.

    PubMed

    Amran, Tengku Sarah Tengku; Hashim, Md Roslan; Al-Obaidi, Nihad K Ali; Yazid, Hanani; Adnan, Rohana

    2013-01-01

    We present an investigation on a coupled system consists of gold nanoparticles and silicon nanocrystals. Gold nanoparticles (AuNPs) embedded into porous silicon (PSi) were prepared using the electrochemical deposition method. Scanning electron microscope images and energy-dispersive X-ray results indicated that the growth of AuNPs on PSi varies with current density. X-ray diffraction analysis showed the presence of cubic gold phases with crystallite sizes around 40 to 58 nm. Size dependence on the plasmon absorption was studied from nanoparticles with various sizes. Comparison with the reference sample, PSi without AuNP deposition, showed a significant blueshift with decreasing AuNP size which was explained in terms of optical coupling between PSi and AuNPs within the pores featuring localized plasmon resonances. PMID:23331761

  7. Optical absorption and photoluminescence studies of gold nanoparticles deposited on porous silicon

    NASA Astrophysics Data System (ADS)

    Amran, Tengku Sarah Tengku; Hashim, Md Roslan; Al-Obaidi, Nihad K. Ali; Yazid, Hanani; Adnan, Rohana

    2013-01-01

    We present an investigation on a coupled system consists of gold nanoparticles and silicon nanocrystals. Gold nanoparticles (AuNPs) embedded into porous silicon (PSi) were prepared using the electrochemical deposition method. Scanning electron microscope images and energy-dispersive X-ray results indicated that the growth of AuNPs on PSi varies with current density. X-ray diffraction analysis showed the presence of cubic gold phases with crystallite sizes around 40 to 58 nm. Size dependence on the plasmon absorption was studied from nanoparticles with various sizes. Comparison with the reference sample, PSi without AuNP deposition, showed a significant blueshift with decreasing AuNP size which was explained in terms of optical coupling between PSi and AuNPs within the pores featuring localized plasmon resonances.

  8. A mechanochemical method for the synthesis of passivated silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Heintz, Andrew S.

    Silicon nanoparticles can display properties that are very different from bulk silicon, and as such have potential applications in optoelectronic devices and as fluorescent biomarkers. However, silicon nanoparticles can experience significant degradation to luminescence upon ambient air oxidation. As most real-world applications for luminescent silicon nanoparticles would of course result in exposure to air, it becomes necessary to protect the particle surface in an effort to prevent ambient air oxidation. A mechanochemical method for the production of passivated silicon nanoparticles has been developed. This process presents a simple, straightforward, and robust route for the simultaneous production of silicon nanoparticles and the passivation of the nanoparticle surface with covalently bound organic molecules. This procedure has shown to be effective for organic liquids of a wide range of functionalities. Alkynes, alkenes, aldehydes, carboxylic acids, and alcohols have all shown success in passivation of the nanoparticle surface. For example, passivated silicon nanoparticles produced in 1-octyne emit at 435 nm when excited with 360 nm light, and display a quantum yield of 0.60. As they are produced, the smaller nanoparticles become solubilized in the organic liquid medium. Chain length variations in the passivating molecule have shown to affect the size of the silicon nanoparticles that become solubilized in the liquid medium after milling. Process yields increase from 4.1% to 5.2% when the functionalizing chain length is increased from 6 to 12. This allows for a degree of nanoparticle size selection by simple alteration of reactive organic selection. Initial investigations into process optimization were performed. Increasing the number of milling balls to three was found to increase process yield. Additionally, silicon was found to be an excess reactant, and thus decreasing the initial charge of silicon was shown to reduce process waste. The developed process

  9. Mapping the plasmonic response of gold nanoparticles embedded in TiO2 thin films

    NASA Astrophysics Data System (ADS)

    Diaz-Egea, Carlos; Ben, Teresa; Herrera, Miriam; Hernández, Jesús; Pedrueza, Esteban; Valdés, José L.; Martínez-Pastor, Juan P.; Attouchi, F.; Mafhoud, Z.; Stéphan, Odile; Molina, Sergio I.

    2015-10-01

    We present the mapping of the plasmonic properties of gold nanoparticles that are embedded in a TiO2 thin film deposited over two different substrates, glass and silicon. An improved electron energy-loss spectroscopy (EELS) imaging technique was used to extract plasmon maps with nanometre resolution. Several representative cases of randomly dispersed NPs have been examined to carefully evaluate surrounding effects on the optical response of such nanostructured material. Data were compared to analytical calculations and showed good agreement. These results validate previous structural and far-field optical results and provide a clear description of the optical phenomena that take place at a nanometre scale in these materials. They are of primary importance for enlightening the way to the fabrication of thin film materials including metallic nanostructures for photovoltaic applications.

  10. Mapping the plasmonic response of gold nanoparticles embedded in TiO₂ thin films.

    PubMed

    Diaz-Egea, Carlos; Ben, Teresa; Herrera, Miriam; Hernández, Jesús; Pedrueza, Esteban; Valdés, José L; Martínez-Pastor, Juan P; Attouchi, F; Mafhoud, Z; Stéphan, Odile; Molina, Sergio I

    2015-10-01

    We present the mapping of the plasmonic properties of gold nanoparticles that are embedded in a TiO2 thin film deposited over two different substrates, glass and silicon. An improved electron energy-loss spectroscopy (EELS) imaging technique was used to extract plasmon maps with nanometre resolution. Several representative cases of randomly dispersed NPs have been examined to carefully evaluate surrounding effects on the optical response of such nanostructured material. Data were compared to analytical calculations and showed good agreement. These results validate previous structural and far-field optical results and provide a clear description of the optical phenomena that take place at a nanometre scale in these materials. They are of primary importance for enlightening the way to the fabrication of thin film materials including metallic nanostructures for photovoltaic applications. PMID:26377736

  11. Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response.

    PubMed

    Dmitriev, Pavel A; Baranov, Denis G; Milichko, Valentin A; Makarov, Sergey V; Mukhin, Ivan S; Samusev, Anton K; Krasnok, Alexander E; Belov, Pavel A; Kivshar, Yuri S

    2016-05-01

    Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. PMID:27113352

  12. Silicon nanocrystal-noble metal hybrid nanoparticles.

    PubMed

    Sugimoto, H; Fujii, M; Imakita, K

    2016-06-01

    We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion. PMID:27121127

  13. Noble metal nanoparticles embedding into polymeric materials: From fundamentals to applications.

    PubMed

    Prakash, Jai; Pivin, J C; Swart, H C

    2015-12-01

    This review covers some key concepts related to embedding of the noble metal nanoparticles in polymer surfaces. The metal nanoparticles embedded into the polymer matrix can provide high-performance novel materials that find applications in modern nanotechnology. In particular, the origin of various processes that drive the embedding phenomenon, growth of the nanostructure at the surface, factors affecting the embedding including role of surface, interface energies and thermodynamic driving forces with emphasis on the fundamental and technological applications, under different conditions (annealing and ion beams) have been discussed. In addition to the conventional thermal process for embedding which includes the measure of fundamental polymer surface properties with relevant probing techniques, this review discusses the recent advances carried out in the understanding of embedding phenomenon starting from thin metal films to growth of the nanoparticles and embedded nanostructures using novel ion beam techniques. PMID:26584861

  14. Growth of silicon quantum dots by oxidation of the silicon nanocrystals embedded within silicon carbide matrix

    SciTech Connect

    Kole, Arindam; Chaudhuri, Partha

    2014-10-15

    A moderately low temperature (≤800 °C) thermal processing technique has been described for the growth of the silicon quantum dots (Si-QD) within microcrystalline silicon carbide (μc-SiC:H) dielectric thin films deposited by plasma enhanced chemical vapour deposition (PECVD) process. The nanocrystalline silicon grains (nc-Si) present in the as deposited films were initially enhanced by aluminium induced crystallization (AIC) method in vacuum at a temperature of T{sub v} = 525 °C. The samples were then stepwise annealed at different temperatures T{sub a} in air ambient. Analysis of the films by FTIR and XPS reveal a rearrangement of the μc-SiC:H network has taken place with a significant surface oxidation of the nc-Si domains upon annealing in air. The nc-Si grain size (D{sub XRD}) as calculated from the XRD peak widths using Scherrer formula was found to decrease from 7 nm to 4 nm with increase in T{sub a} from 250 °C to 800 °C. A core shell like structure with the nc-Si as the core and the surface oxide layer as the shell can clearly describe the situation. The results indicate that with the increase of the annealing temperature in air the oxide shell layer becomes thicker and the nc-Si cores become smaller until their size reduced to the order of the Si-QDs. Quantum confinement effect due to the SiO covered nc-Si grains of size about 4 nm resulted in a photoluminescence peak due to the Si QDs with peak energy at 1.8 eV.

  15. Monolithic cryopolymers with embedded nanoparticles. I. Capillary liquid chromatography of proteins using neutral embedded nanoparticles.

    PubMed

    Dario Arrua, R; Nordborg, Anna; Haddad, Paul R; Hilder, Emily F

    2013-01-18

    Rigid monolithic cryostructures were prepared in capillary format at sub-zero temperatures and used successfully in the separation of proteins by hydrophobic interaction chromatography (HIC). The polymerization mixture consisted of poly(ethyleneglycol) diacrylate (PEGDA) M(n)∼258 as the single monomer, a mixture of dioxane and water as the porogen and N,N,N',N'-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) as the initiator system. At sub-zero temperatures, the solvent mixture used as the porogen is frozen, leading to the formation of a polymeric structure templated by the solvent crystals that are formed. The optimization of the polymerization reaction was carried out by studying the influence of different reaction parameters including the temperature of the reaction, monomer concentration and solvent, on the porous characteristics of the polymers obtained. Separations were performed in HIC mode using 3 M ammonium sulfate in 0.1 M phosphate buffer, pH 6.9 to 0.1 M phosphate buffer, pH 6.9 over a 15 min gradient. The addition of neutral nanoparticles synthesized by mini-emulsion polymerization greatly improved the separation of the protein mixture, doubling the peak capacity of the control column without nanoparticles (from 7 to 17). Although the peak capacities and resolution values achieved were lower than those reported for conventional methacrylate monolithic columns, the use of this polymerization approach allows the preparation of polymeric structures which presented a more open porous structure and consequently exhibited significantly higher permeability than conventional polymer monoliths. PMID:23273630

  16. Cytotoxicity of titanium and silicon dioxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Wagner, Stefanie; Münzer, Simon; Behrens, Peter; Scheper, Thomas; Bahnemann, Detlef; Kasper, Cornelia

    2009-05-01

    Different TiO2 and SiO2 nanoparticles have been tested concerning their toxicity on selected mammalian cell lines. Various powders and suspensions, all of which consist of titanium or silicon dioxide nanoparticles have been examined. These particles differ in the crystal structure, the size and the BET-surface area. There was also a classification in fixed particles and in particles easily accessible in solution. With focus on the possible adsorption of the nanoparticles into the human organism, via skin and via respiratory tract, the effects on fibroblasts (NIH-3T3) and on a human lung adenocarcinoma epithelial cell line were examined. Additionally, the particles were tested with HEP-G2 cells, which are often used as model cell line for biocompatibility tests, and PC-12 cells, a rat adrenal pheochromocytoma cell line. The viability of the cells was examined by the MTT-test. The viability results were found to partly depend on the type of cells used. The experimental results show that the adhesion of the cells on the different powders strongly depends on the type of cell lines as well as on the type of powder. It was found that the lower viability of some cells on the powder coatings is not only caused by a cytotoxicity effect of the powders, but is also due to a lower adhesion of the cells on the particle surfaces. Furthermore, it could be shown that the physical properties of the powders cannot be easily correlated to any observed biological effect. While some powders show a significant suppression of the cell growth, others with similar physical properties indicate no toxic effect.

  17. Laser-generated plasma by carbon nanoparticles embedded into polyethylene

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Ceccio, G.; Cutroneo, M.

    2016-05-01

    Carbon nanoparticles have been embedded into polyethylene at different concentrations by using chemical-physical processes. The synthesized material was characterized in terms of physical modifications concerning the mechanical, compositional and optical properties. Obtained flat targets have been irradiated by Nd:YAG laser at intensities of the order of 1010 W/cm2 in order to generate non-equilibrium plasma in vacuum. The laser-matter interaction produces charge separation effects with consequent acceleration of protons and carbon ions. Plasma was characterized using time-of-flight measurements of the accelerated ions. Applications of the produced targets in order to generate carbon ion beams from laser-generated plasma are presented and discussed.

  18. Shrinking of silicon nanocrystals embedded in an amorphous silicon oxide matrix during rapid thermal annealing in a forming gas atmosphere

    NASA Astrophysics Data System (ADS)

    van Sebille, M.; Fusi, A.; Xie, L.; Ali, H.; van Swaaij, R. A. C. M. M.; Leifer, K.; Zeman, M.

    2016-09-01

    We report the effect of hydrogen on the crystallization process of silicon nanocrystals embedded in a silicon oxide matrix. We show that hydrogen gas during annealing leads to a lower sub-band gap absorption, indicating passivation of defects created during annealing. Samples annealed in pure nitrogen show expected trends according to crystallization theory. Samples annealed in forming gas, however, deviate from this trend. Their crystallinity decreases for increased annealing time. Furthermore, we observe a decrease in the mean nanocrystal size and the size distribution broadens, indicating that hydrogen causes a size reduction of the silicon nanocrystals.

  19. Silver-nanoparticle-embedded antimicrobial paints based on vegetable oil

    NASA Astrophysics Data System (ADS)

    Kumar, Ashavani; Vemula, Praveen Kumar; Ajayan, Pulickel M.; John, George

    2008-03-01

    Developing bactericidal coatings using simple green chemical methods could be a promising route to potential environmentally friendly applications. Here, we describe an environmentally friendly chemistry approach to synthesize metal-nanoparticle (MNP)-embedded paint, in a single step, from common household paint. The naturally occurring oxidative drying process in oils, involving free-radical exchange, was used as the fundamental mechanism for reducing metal salts and dispersing MNPs in the oil media, without the use of any external reducing or stabilizing agents. These well-dispersed MNP-in-oil dispersions can be used directly, akin to commercially available paints, on nearly all kinds of surface such as wood, glass, steel and different polymers. The surfaces coated with silver-nanoparticle paint showed excellent antimicrobial properties by killing both Gram-positive human pathogens (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). The process we have developed here is quite general and can be applied in the synthesis of a variety of MNP-in-oil systems.

  20. Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response

    NASA Astrophysics Data System (ADS)

    Dmitriev, Pavel A.; Baranov, Denis G.; Milichko, Valentin A.; Makarov, Sergey V.; Mukhin, Ivan S.; Samusev, Anton K.; Krasnok, Alexander E.; Belov, Pavel A.; Kivshar, Yuri S.

    2016-05-01

    Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions.Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07965a

  1. Toxicity of Nanoparticles Embedded in Paints Compared with Pristine Nanoparticles in Mice

    PubMed Central

    Smulders, Stijn; Luyts, Katrien; Brabants, Gert; Landuyt, Kirsten Van; Kirschhock, Christine; Smolders, Erik; Golanski, Luana; Vanoirbeek, Jeroen; Hoet, Peter HM

    2014-01-01

    The unique physical and chemical properties of nanomaterials have led to their increased use in many industrial applications, including as a paint additive. For example, titanium dioxide (TiO2) engineered nanoparticles (ENPs) have well-established anti-UV, self-cleaning, and air purification effects. Silver (Ag) ENPs are renowned for their anti-microbial capabilities and silicon dioxide (SiO2) ENPs are used as fire retardants and anti-scratch coatings. In this study, the toxic effects and biodistribution of three pristine ENPs (TiO2, Ag, and SiO2), three aged paints containing ENPs (TiO2, Ag, and SiO2) along with control paints without ENPs were compared. BALB/c mice were oropharyngeally aspirated with ENPs or paint particles (20 μg/aspiration) once a week for 5 weeks and sacrificed either 2 or 28 days post final aspiration treatment. A bronchoalveolar lavage was performed and systemic blood toxicity was evaluated to ascertain cell counts, induction of inflammatory cytokines, and key blood parameters. In addition, the lung, liver, kidney, spleen, and heart were harvested and metal concentrations were determined. Exposure to pristine ENPs caused subtle effects in the lungs and negligible alterations in the blood. The most pronounced toxic effects were observed after Ag ENPs exposure; an increased neutrophil count and a twofold increase in pro-inflammatory cytokine secretion (keratinocyte chemoattractant (KC) and interleukin-1ß (IL-1ß)) were identified. The paint containing TiO2 ENPs did not modify macrophage and neutrophil counts, but mildly induced KC and IL-1ß. The paints containing Ag or SiO2 did not show significant toxicity. Biodistribution experiments showed distribution of Ag and Si outside the lung after aspiration to respectively pristine Ag or SiO2 ENPs. In conclusion, we demonstrated that even though direct exposure to ENPs induced some toxic effects, once they were embedded in a complex paint matrix little to no adverse toxicological effects were

  2. Toxicity of nanoparticles embedded in paints compared with pristine nanoparticles in mice.

    PubMed

    Smulders, Stijn; Luyts, Katrien; Brabants, Gert; Landuyt, Kirsten Van; Kirschhock, Christine; Smolders, Erik; Golanski, Luana; Vanoirbeek, Jeroen; Hoet, Peter H M

    2014-09-01

    The unique physical and chemical properties of nanomaterials have led to their increased use in many industrial applications, including as a paint additive. For example, titanium dioxide (TiO2) engineered nanoparticles (ENPs) have well-established anti-UV, self-cleaning, and air purification effects. Silver (Ag) ENPs are renowned for their anti-microbial capabilities and silicon dioxide (SiO2) ENPs are used as fire retardants and anti-scratch coatings. In this study, the toxic effects and biodistribution of three pristine ENPs (TiO2, Ag, and SiO2), three aged paints containing ENPs (TiO2, Ag, and SiO2) along with control paints without ENPs were compared. BALB/c mice were oropharyngeally aspirated with ENPs or paint particles (20 μg/aspiration) once a week for 5 weeks and sacrificed either 2 or 28 days post final aspiration treatment. A bronchoalveolar lavage was performed and systemic blood toxicity was evaluated to ascertain cell counts, induction of inflammatory cytokines, and key blood parameters. In addition, the lung, liver, kidney, spleen, and heart were harvested and metal concentrations were determined. Exposure to pristine ENPs caused subtle effects in the lungs and negligible alterations in the blood. The most pronounced toxic effects were observed after Ag ENPs exposure; an increased neutrophil count and a twofold increase in pro-inflammatory cytokine secretion (keratinocyte chemoattractant (KC) and interleukin-1ß (IL-1ß)) were identified. The paint containing TiO2 ENPs did not modify macrophage and neutrophil counts, but mildly induced KC and IL-1ß. The paints containing Ag or SiO2 did not show significant toxicity. Biodistribution experiments showed distribution of Ag and Si outside the lung after aspiration to respectively pristine Ag or SiO2 ENPs. In conclusion, we demonstrated that even though direct exposure to ENPs induced some toxic effects, once they were embedded in a complex paint matrix little to no adverse toxicological effects were

  3. Silicon nanoparticles: applications in cell biology and medicine

    PubMed Central

    O’Farrell, Norah; Houlton, Andrew; Horrocks, Benjamin R

    2006-01-01

    In this review, we describe the synthesis, physical properties, surface functionalization, and biological applications of silicon nanoparticles (also known as quantum dots). We compare them against current technologies, such as fluorescent organic dyes and heavy metal chalcogenide-based quantum dots. In particular, we examine the many different methods that can be used to both create and modify these nanoparticles and the advantages they may have over current technologies that have stimulated research into designing silicon nanoparticles for in vitro and in vivo applications. PMID:17722279

  4. The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Granitzer, P.; Rumpf, K.; Gonzalez-Rodriguez, R.; Coffer, J. L.; Reissner, M.

    2015-11-01

    The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay with the iron oxide nanoparticle size, plays a sensitive role. It is shown that Fe3O4 loaded porous silicon and SiNTs differ significantly in their magnetic behavior, especially the transition between superparamagnetic behavior and blocked state, due to host morphology-dependent magnetic interactions. Importantly, it is found that all investigated samples meet the magnetic precondition of possible biomedical applications of exhibiting a negligible magnetic remanence at room temperature.The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay

  5. Silicon nanocrystal-noble metal hybrid nanoparticles

    NASA Astrophysics Data System (ADS)

    Sugimoto, H.; Fujii, M.; Imakita, K.

    2016-05-01

    We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion.We report a novel and facile self-limiting synthesis route of silicon nanocrystal (Si NC)-based colloidally stable semiconductor-metal (gold, silver and platinum) hybrid nanoparticles (NPs). For the formation of hybrid NPs, we employ ligand-free colloidal Si NCs with heavily boron (B) and phosphorus (P) doped shells. By simply mixing B and P codoped colloidal Si NCs with metal salts, hybrid NPs consisting of metal cores and Si NC shells are spontaneously formed. We demonstrate the synthesis of highly uniform and size controllable hybrid NPs. It is shown that codoped Si NCs act as a reducing agent for metal salts and also as a protecting layer to stop metal NP growth. The process is thus self-limiting. The development of a variety of Si NC-based hybrid NPs is a promising first step for the design of biocompatible multifunctional NPs with broad material choices for biosensing, bioimaging and solar energy conversion. Electronic supplementary information (ESI) available: Additional TEM images and extinction spectra of Si-metal hybrid NPs are shown in Fig. S1

  6. Silicon photonics packaging with lateral fiber coupling to apodized grating coupler embedded circuit.

    PubMed

    Li, Chao; Chee, Koh Sing; Tao, Jifang; Zhang, Huijuan; Yu, Mingbin; Lo, G Q

    2014-10-01

    We report a novel lateral packaging approach using laser welding technique with angle polished fiber coupling to grating coupler embedded silicon photonic circuit. Measurements show the relax alignment tolerance for fiber packaging process. The packaging excess loss of 1.2 dB is achieved. The use of angle polished fiber for lateral fiber coupling enables an alternative way for cost-effective deployment of silicon photonics packaging in telecommunication systems. PMID:25321998

  7. Multifunctional porous silicon nanoparticles for cancer theranostics.

    PubMed

    Wang, Chang-Fang; Sarparanta, Mirkka P; Mäkilä, Ermei M; Hyvönen, Maija L K; Laakkonen, Pirjo M; Salonen, Jarno J; Hirvonen, Jouni T; Airaksinen, Anu J; Santos, Hélder A

    2015-04-01

    Nanomaterials provide a unique platform for the development of theranostic systems that combine diagnostic imaging modalities with a therapeutic payload in a single probe. In this work, dual-labeled iRGD-modified multifunctional porous silicon nanoparticles (PSi NPs) were prepared from dibenzocyclooctyl (DBCO) modified PSi NPs by strain-promoted azide-alkyne cycloaddition (SPAAC) click chemistry. Hydrophobic antiangiogenic drug, sorafenib, was loaded into the modified PSi NPs to enhance the drug dissolution rate and improve cancer therapy. Radiolabeling of the developed system with (111)In enabled the monitoring of the in vivo biodistribution of the nanocarrier by single photon emission computed tomography (SPECT) in an ectopic PC3-MM2 mouse xenograft model. Fluorescent labeling with Alexa Fluor 488 was used to determine the long-term biodistribution of the nanocarrier by immunofluorescence at the tissue level ex vivo. Modification of the PSi NPs with an iRGD peptide enhanced the tumor uptake of the NPs when administered intravenously. After intratumoral delivery the NPs were retained in the tumor, resulting in efficient tumor growth suppression with particle-loaded sorafenib compared to the free drug. The presented multifunctional PSi NPs highlight the utility of constructing a theranostic nanosystems for simultaneous investigations of the in vivo behavior of the nanocarriers and their drug delivery efficiency, facilitating the selection of the most promising materials for further NP development. PMID:25701036

  8. Strong visible electroluminescence from silicon nanocrystals embedded in a silicon carbide film

    SciTech Connect

    Huh, Chul Kim, Tae-Youb; Ahn, Chang-Geun; Kim, Bong Kyu

    2015-05-25

    We report the strong visible light emission from silicon (Si) nanocrystals (NCs) embedded in a Si carbide (SiC) film. Compared to Si NC light-emitting diode (LED) by employing the Si nitride (SiN{sub x}) film as a surrounding matrix, the turn-on voltage of the Si NC LED with the SiC film was significantly decreased by 4 V. This was attributed to a smaller barrier height for injecting the electrons into the Si NCs due to a smaller band gap of SiC film than a SiN{sub x} film. The electroluminescence spectra increases with increasing forward voltage, indicating that the electrons are efficiently injected into the Si NCs in the SiC film. The light output power shows a linear increase with increasing forward voltage. The light emission originated from the Si NCs in a SiC film was quite uniform. The power efficiency of the Si NC LED with the SiC film was 1.56 times larger than that of the Si NC LED with the SiN{sub x} film. The Si NCs in a SiC film show unique advantages and are a promising candidate for application in optical devices.

  9. Three dimensional design of silver nanoparticle assemblies embedded in dielectrics for Raman spectroscopy enhancement and dark-field imaging.

    PubMed

    Carles, Robert; Farcau, Cosmin; Bonafos, Caroline; Benassayag, Gérard; Bayle, Maxime; Benzo, Patrizio; Groenen, Jesse; Zwick, Antoine

    2011-11-22

    A strategy to design and fabricate hybrid metallic-dielectric substrates for optical spectroscopy and imaging is proposed. Different architectures consisting of three-dimensional patterns of metallic nanoparticles embedded in dielectric layers are conceived to simultaneously exploit the optical interference phenomenon in stratified media and localized surface plasmon resonances on metal nanoparticles. These structures are based on a simultaneous control of opto-electronic properties at three scales (3S) (~2/20/200 nm) and along three directions (3D). By ultralow energy ion implantation through a microfabricated stencil we precisely control the size, density, and location of silver nanoparticles embedded in silica/silicon thin films. Elastic (Rayleigh) and inelastic (Raman) scattering imaging assisted by simulations were used to analyze the optical response of these "3S-3D" patterned layers. The reflectance contrast is strongly enhanced when resonance conditions between the stationary electromagnetic field in the dielectric matrix and the localized plasmon resonance in the silver nanoparticles are realized. The potential of these 3S-3D metal-dielectric structures as surface-enhanced Raman scattering substrates is demonstrated. These novel kinds of plasmonic-photonic architectures are reproducible and stable; they preserve flat and chemically uniform surfaces, offering opportunities for the development of efficient and reusable substrates for optical spectroscopy and imaging enhancement. PMID:21988138

  10. Evaluation of Cytotoxicity and Hypoxic Effect of Nitroimidazole Embedded Nanoparticles.

    PubMed

    Sharma, Rakesh; Kwon, Soonjo

    2016-05-01

    Adenylate cyclase is a key intracellular enzyme involved in energy imbalance leading to tumor hypoxia and cytotoxicity. In this study, adenylate cyclase activities in isolated hepatocytes and Kupffer cells were compared in the presence of several metabolic stimulators. In cultured hepatocyte cells, adenylate cyclase was stimulated by guanylyl imidotriphosphate (GITP), guanosine triphosphate (GTP), progesterone and nitroimidazole embedded nanoparticle (NNP) effectors, while prostaglandin E2 and F2α were used as effectors in cultured Kupffer cells. The results showed that NNPs decreased adenylate cyclase specific activity in a dose-dependent manner after preincubation of hepatocytes with NNPs. The NNPs stimulated adenylate cyclase activities in hepatocytes were evaluated based on measurement of cyclic adenosine monophosphate (cAMP). The stimulatory effects of NNPs on adenylate cyclase were independent of the presence of GTP and may have been due to a direct effect on the catalytic subunit of adenylate cyclase. In addition, basal cAMP generation in hepatocyte cells was efficiently suppressed by the NNPs. In conclusion, NNPs exerted direct effects on the catalytic subunit of the adenylate cyclase system, and adenylate cyclase was hormone sensitive in liver cells. PMID:27483789

  11. Iron nanoparticles embedded in carbon films: structural and optical properties

    NASA Astrophysics Data System (ADS)

    Mashayekhi, Fatemeh; Shafiekhani, Azizollah; Sebt, Seyed Ali

    2016-06-01

    In the present work amorphous hydrogenated carbon films with sputtered iron nanoparticles (Fe NPs @ a-C:H) were deposited by co-deposition of RF-sputtering and RF-plasma enhanced chemical vapor deposition methods using acetylene gas and iron target on quartz and silicon substrates. Samples were prepared in different initial pressures and during constant deposition time. The crystalline structure of Fe NPs @ a-C:H was studied using X-ray diffraction and selected area electron diffraction patterns. The X-ray photoelectron spectroscopy analysis presents that increasing the initial pressure decreases the atomic ratio of Fe/C and the sp3-hybridized carbon content in prepared samples. The transmission electron microscope image shows the encapsulated Fe NPs in carbon films. The optical properties and localized surface plasmon resonance (LSPR) of samples were studied using UV-visible spectrophotometry, which is shown that increasing of Fe content decreases the intensity of LSPR peak and increases the optical band gap.

  12. Gold and Gallium Nanoparticle Growth on Silicon (100)

    NASA Astrophysics Data System (ADS)

    Madsen, Rees; Brown, Hunter L.; Ames, Sadie; Rasmussen, J. Leland; Tobler, Samuel

    2014-03-01

    Nanoparticles are used for various applications in today's research. Some researcher's interests involve using the nanoparticles to grow silicon nanowires on a silicon substrate. Before growing nanowires can be accomplished a study must be made of the formation of nanoparticles. Most often the metal used to make the nanoparticles is gold. In this study both gold and gallium were used to make the nanoparticles, by thermal evaporation. The gold and gallium nanoparticles were grown on silicon (100). Between one to three monolayers of material was added to the substrate, with the particle sizes ranging from 0.5 microns to 3 microns in diameter. Densities of nanoparticles varied based on the time of growth and on the intensity of the source. The variable sizes were seen with sample temperatures between 700 C and 900 C measured using a disappearing filament optical pyrometer. The growth process occurred at pressures below 3e-7 Torr. This presentation will summarize the growth process and show the similarities and differences between the two metals.

  13. Silver nanoparticles-coated glass frits for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Li, Yingfen; Gan, Weiping; Li, Biyuan

    2016-04-01

    Silver nanoparticles-coated glass frit composite powders for silicon solar cells were prepared by electroless plating. Silver colloids were used as the activating agent of glass frits. The products were characterized by X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry. The characterization results indicated that silver nanoparticles with the melting temperature of 838 °C were uniformly deposited on glass frit surface. The particle size of silver nanoparticles could be controlled by adjusting the [Ag(NH3)2]NO3 concentration. The as-prepared composite powders were applied in the front side metallization of silicon solar cells. Compared with those based on pure glass frits, the solar cells containing the composite powders had the denser silver electrodes and the better silver-silicon ohmic contacts. Furthermore, the photovoltaic performances of solar cells were improved after the electroless plating.

  14. Nanoparticle production in arc generated fireballs of granular silicon powder

    NASA Astrophysics Data System (ADS)

    Ito, Tsuyohito; Cappelli, Mark A.

    2012-03-01

    Recently we observed buoyant fireballs by arc igniting silicon that drift in air for several seconds and postulated that the low aggregate density was attributed to the formation of a network of nanoparticles that must completely surround the burning silicon core, trapping the heated vapor generated as a result of particle combustion [Ito et al. Phys Rev E 80, 067401 (2009)]. In this paper, we describe the capturing of several of these fireballs in flight, and have characterized their nanostructure by high resolution microscopy. The nanoparticle network is found to have an unusually high porosity (> 99%), suggesting that this arc-ignition of silicon can be a novel method of producing ultra-porous silica. While we confirm the presence of a nanoparticle network within the fireballs, the extension of this mechanism to the production of ball lightning during atmospheric lightning strikes in nature is still the subject of ongoing debate.

  15. Nickel nanoparticles embedded in carbon foam for improving electromagnetic shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Kumar, Rajeev; Kumari, Saroj; Dhakate, Sanjay R.

    2014-08-01

    To improve electromagnetic shielding effectiveness of light weight carbon foam (CF), magnetic nanoparticles were embedded in it during processing. The CF was developed from the coal tar pitch and mixture of coal tar pitch-Nickel (Ni) nanoparticles by sacrificial template technique and heat treated to up 1,000 °C. To ascertain the effect of Ni nanoparticles embedded in CF, it was characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, vector network analyzer and vibration sample magnetometer. It is observed that Ni nanoparticles embedded in the carbon material play an important role for improving the structure and electrical conductivity of CF-Ni by catalytic carbonization. The structural investigation suggests that the Ni nanoparticles embedded in the carbon material in bulk as well on the surface of CF. The CF demonstrates excellent shielding response in the frequency range 8.2-12.4 GHz in which total shielding effectiveness (SE) dominated by absorption losses. The total SE is -25 and -61 dB of CF and CF-Ni, it is governed by absorption losses -48.5 dB in CF-Ni. This increase is due to the increase in dielectric and magnetic losses of ferromagnetic Ni nanoparticles with high surface area. Thus, light weight CF embedded with small amount of magnetic nanoparticles can be useful material for stealth technology.

  16. Nickel nanoparticles embedded in carbon foam for improving electromagnetic shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Kumar, Rajeev; Kumari, Saroj; Dhakate, Sanjay R.

    2015-06-01

    To improve electromagnetic shielding effectiveness of light weight carbon foam (CF), magnetic nanoparticles were embedded in it during processing. The CF was developed from the coal tar pitch and mixture of coal tar pitch-Nickel (Ni) nanoparticles by sacrificial template technique and heat treated to up 1,000 °C. To ascertain the effect of Ni nanoparticles embedded in CF, it was characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, vector network analyzer and vibration sample magnetometer. It is observed that Ni nanoparticles embedded in the carbon material play an important role for improving the structure and electrical conductivity of CF-Ni by catalytic carbonization. The structural investigation suggests that the Ni nanoparticles embedded in the carbon material in bulk as well on the surface of CF. The CF demonstrates excellent shielding response in the frequency range 8.2-12.4 GHz in which total shielding effectiveness (SE) dominated by absorption losses. The total SE is -25 and -61 dB of CF and CF-Ni, it is governed by absorption losses -48.5 dB in CF-Ni. This increase is due to the increase in dielectric and magnetic losses of ferromagnetic Ni nanoparticles with high surface area. Thus, light weight CF embedded with small amount of magnetic nanoparticles can be useful material for stealth technology.

  17. Selective silicon nanoparticle growth on high-density arrays of silicon nitride

    NASA Astrophysics Data System (ADS)

    Coffee, Shawn S.; Shahrjerdi, Davood; Banerjee, Sanjay K.; Ekerdt, John G.

    2007-10-01

    Selective silicon nanoparticle deposition from disilane on ˜17 nm diameter Si 3N 4 features defined through a 15-nm-thick SiO 2 masking layer was studied using hot wire chemical vapor deposition between 900 and 1025 K, and chemical vapor deposition between 900 and 975 K. Thin film poly(styrene-b-methyl methacrylate) diblock copolymer was used to generate cylinders with a density of 6×10 10 cm -2 that served as the patterning template. Silicon adatom etching of SiO 2 and diffusion of adatoms to the Si 3N 4 regions prevented the accumulation of adatoms necessary for nanoparticle nucleation and growth on the SiO 2 surfaces. Nanoparticles form selectively on Si 3N 4, because adsorbed Si does not etch this surface. Incident flux, total exposure, and substrate temperature were adjusted to explore nanoparticle deposition trends relating relative adatom concentration with nanoparticle density and size distributions.

  18. Optical Manipulation and Spectroscopy Of Silicon Nanoparticles Exhibiting Dielectric Resonances.

    PubMed

    Andres-Arroyo, Ana; Gupta, Bakul; Wang, Fan; Gooding, J Justin; Reece, Peter J

    2016-03-01

    We demonstrate that silicon (Si) nanoparticles with scattering properties exhibiting strong dielectric resonances can be successfully manipulated using optical tweezers. The large dielectric constant of Si has a distinct advantage over conventional colloidal nanoparticles in that it leads to enhanced trapping forces without the heating associated with metallic nanoparticles. Further, the spectral features of the trapped nanoparticles provide a unique marker for probing size, shape, orientation and local dielectric environment. We exploit these properties to investigate the trapping dynamics of Si nanoparticles with different dimensions ranging from 50 to 200 nm and aspect ratios between 0.4 and 2. The unique combination of spectral and trapping properties make Si nanoparticles an ideal system for delivering directed nanoscale sensing in a range of potential applications. PMID:26848883

  19. Magnetoacoustic imaging of magnetic iron oxide nanoparticles embedded in biological tissues with microsecond magnetic stimulation

    NASA Astrophysics Data System (ADS)

    Hu, Gang; He, Bin

    2012-01-01

    We present an experimental study on magnetoacoustic imaging of superparamagnetic iron oxide (SPIO) nanoparticles embedded in biological tissues. In experiments, a large-current-carrying coil is used to deliver microsecond pulsed magnetic stimulation to samples. The ultrasound signals induced by magnetic forces on SPIO nanoparticles are measured by a rotating transducer. The distribution of nanoparticles is reconstructed by a back-projection imaging algorithm. The results demonstrated the feasibility to obtain cross-sectional image of magnetic nanoparticle targets with faithful dimensional and positional information, which suggests a promising tool for tomographic reconstruction of magnetic nanoparticle-labeled diseased tissues (e.g., cancerous tumor) in molecular or clinic imaging.

  20. Microwave absorber based on silver nanoparticle-embedded polymer thin film.

    PubMed

    Ramesh, G V; Sudheendran, K; Raju, K C James; Sreedhar, B; Radhakrishnan, T P

    2009-01-01

    Silver nanoparticle-embedded poly(vinyl alcohol) films are fabricated through a simple in situ process. The nanocomposite films are a few hundred nanometers thick with silver concentrations below 10% and the nanoparticles 5-10 nm in diameter. These films are shown to exhibit appreciable microwave absorption in the 8-12 GHz range; the return and insertion losses are found to be sensitive to the nanoparticle content. PMID:19441305

  1. Fatigue degradation and electric recovery in Silicon solar cells embedded in photovoltaic modules

    PubMed Central

    Paggi, Marco; Berardone, Irene; Infuso, Andrea; Corrado, Mauro

    2014-01-01

    Cracking in Silicon solar cells is an important factor for the electrical power-loss of photovoltaic modules. Simple geometrical criteria identifying the amount of inactive cell areas depending on the position of cracks with respect to the main electric conductors have been proposed in the literature to predict worst case scenarios. Here we present an experimental study based on the electroluminescence (EL) technique showing that crack propagation in monocrystalline Silicon cells embedded in photovoltaic (PV) modules is a much more complex phenomenon. In spite of the very brittle nature of Silicon, due to the action of the encapsulating polymer and residual thermo-elastic stresses, cracked regions can recover the electric conductivity during mechanical unloading due to crack closure. During cyclic bending, fatigue degradation is reported. This pinpoints the importance of reducing cyclic stresses caused by vibrations due to transportation and use, in order to limit the effect of cracking in Silicon cells. PMID:24675974

  2. Fatigue degradation and electric recovery in Silicon solar cells embedded in photovoltaic modules.

    PubMed

    Paggi, Marco; Berardone, Irene; Infuso, Andrea; Corrado, Mauro

    2014-01-01

    Cracking in Silicon solar cells is an important factor for the electrical power-loss of photovoltaic modules. Simple geometrical criteria identifying the amount of inactive cell areas depending on the position of cracks with respect to the main electric conductors have been proposed in the literature to predict worst case scenarios. Here we present an experimental study based on the electroluminescence (EL) technique showing that crack propagation in monocrystalline Silicon cells embedded in photovoltaic (PV) modules is a much more complex phenomenon. In spite of the very brittle nature of Silicon, due to the action of the encapsulating polymer and residual thermo-elastic stresses, cracked regions can recover the electric conductivity during mechanical unloading due to crack closure. During cyclic bending, fatigue degradation is reported. This pinpoints the importance of reducing cyclic stresses caused by vibrations due to transportation and use, in order to limit the effect of cracking in Silicon cells. PMID:24675974

  3. Preparation and characterization of Ag nanoparticle-embedded blank and ligand-anchored silica gels.

    PubMed

    Im, Hee-Jung; Lee, Byung Cheol; Yeon, Jei-Won

    2013-11-01

    Ag nanoparticles, used for halogen (especially iodine) adsorption and an evaluation of halogen behavior, were embedded in synthesized inorganic-organic hybrid gels. In particular, an irradiation method using an electron beam plays a part in introducing Ag nanoparticles to the organofunctionalized silica gels from AgNO3 solutions in a simple way at atmospheric pressure and room temperature. For preparation of the Ag nanoparticle-embedded inorganic-organic hybrid gels, ligands of ethylenediamine (NH2CH2CH2NH-, TMSen) and mercapto (HS-) functionalized three-dimensional porous SiO2 sol-gels were first synthesized through hydrolysis and condensation reactions, and Ag nanoparticles were then embedded into the ethylenediamine- and mercapto-anchored silica gels each, through electron-beam irradiation. The addition of ligands yielded larger average pore sizes than the absence of any ligand. Moreover, the ethylenediamine ligand led to looser structures and better access of the Ag nanoparticles to the ethylenediamine-anchored gel. As a result, more Ag nanoparticles were introduced into the ethylenediamine-anchored gel. The preparation and characterization of Ag nanoparticle-embedded blank and ligand-anchored silica gels are discussed in detail. PMID:24245307

  4. A digitalized silicon microgyroscope based on embedded FPGA.

    PubMed

    Xia, Dunzhu; Yu, Cheng; Wang, Yuliang

    2012-01-01

    This paper presents a novel digital miniaturization method for a prototype silicon micro-gyroscope (SMG) with the symmetrical and decoupled structure. The schematic blocks of the overall system consist of high precision analog front-end interface, high-speed 18-bit analog to digital convertor, a high-performance core Field Programmable Gate Array (FPGA) chip and other peripherals such as high-speed serial ports for transmitting data. In drive mode, the closed-loop drive circuit are implemented by automatic gain control (AGC) loop and software phase-locked loop (SPLL) based on the Coordinated Rotation Digital Computer (CORDIC) algorithm. Meanwhile, the sense demodulation module based on varying step least mean square demodulation (LMSD) are addressed in detail. All kinds of algorithms are simulated by Simulink and DSPbuilder tools, which is in good agreement with the theoretical design. The experimental results have fully demonstrated the stability and flexibility of the system. PMID:23201990

  5. A Digitalized Silicon Microgyroscope Based on Embedded FPGA

    PubMed Central

    Xia, Dunzhu; Yu, Cheng; Wang, Yuliang

    2012-01-01

    This paper presents a novel digital miniaturization method for a prototype silicon micro-gyroscope (SMG) with the symmetrical and decoupled structure. The schematic blocks of the overall system consist of high precision analog front-end interface, high-speed 18-bit analog to digital convertor, a high-performance core Field Programmable Gate Array (FPGA) chip and other peripherals such as high-speed serial ports for transmitting data. In drive mode, the closed-loop drive circuit are implemented by automatic gain control (AGC) loop and software phase-locked loop (SPLL) based on the Coordinated Rotation Digital Computer (CORDIC) algorithm. Meanwhile, the sense demodulation module based on varying step least mean square demodulation (LMSD) are addressed in detail. All kinds of algorithms are simulated by Simulink and DSPbuilder tools, which is in good agreement with the theoretical design. The experimental results have fully demonstrated the stability and flexibility of the system. PMID:23201990

  6. Effect of Surface Treated Silicon Dioxide Nanoparticles on Some Mechanical Properties of Maxillofacial Silicone Elastomer

    PubMed Central

    Zayed, Sara M.; Alshimy, Ahmad M.; Fahmy, Amal E.

    2014-01-01

    Current materials used for maxillofacial prostheses are far from ideal and there is a need for novel improved materials which mimic as close as possible the natural behavior of facial soft tissues. This study aimed to evaluate the effect of adding different concentrations of surface treated silicon dioxide nanoparticles (SiO2) on clinically important mechanical properties of a maxillofacial silicone elastomer. 147 specimens of the silicone elastomer were prepared and divided into seven groups (n = 21). One control group was prepared without nanoparticles and six study groups with different concentrations of nanoparticles, from 0.5% to 3% by weight. Specimens were tested for tear strength (ASTM D624), tensile strength (ASTM D412), percent elongation, and shore A hardness. SEM was used to assess the dispersion of nano-SiO2 within the elastomer matrix. Data were analyzed by one-way ANOVA and Scheffe test (α = 0.05). Results revealed significant improvement in all mechanical properties tested, as the concentration of the nanoparticles increased. This was supported by the results of the SEM. Hence, it can be concluded that the incorporation of surface treated SiO2 nanoparticles at concentration of 3% enhanced the overall mechanical properties of A-2186 silicone elastomer. PMID:25574170

  7. Tin nanoparticles as an effective conductive additive in silicon anodes

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Beaudette, C.; Guo, J.; Bozhilov, K.; Mangolini, L.

    2016-08-01

    We have found that the addition of tin nanoparticles to a silicon-based anode provides dramatic improvements in performance in terms of both charge capacity and cycling stability. Using a simple procedure and off-the-shelf additives and precursors, we developed a structure in which the tin nanoparticles are segregated at the interface between the silicon-containing active layer and the solid electrolyte interface. Even a minor addition of tin, as small as ∼2% by weight, results in a significant decrease in the anode resistance, as confirmed by electrochemical impedance spectroscopy. This leads to a decrease in charge transfer resistance, which prevents the formation of electrically inactive “dead spots” in the anode structure and enables the effective participation of silicon in the lithiation reaction.

  8. Tin nanoparticles as an effective conductive additive in silicon anodes.

    PubMed

    Zhong, L; Beaudette, C; Guo, J; Bozhilov, K; Mangolini, L

    2016-01-01

    We have found that the addition of tin nanoparticles to a silicon-based anode provides dramatic improvements in performance in terms of both charge capacity and cycling stability. Using a simple procedure and off-the-shelf additives and precursors, we developed a structure in which the tin nanoparticles are segregated at the interface between the silicon-containing active layer and the solid electrolyte interface. Even a minor addition of tin, as small as ∼2% by weight, results in a significant decrease in the anode resistance, as confirmed by electrochemical impedance spectroscopy. This leads to a decrease in charge transfer resistance, which prevents the formation of electrically inactive "dead spots" in the anode structure and enables the effective participation of silicon in the lithiation reaction. PMID:27484849

  9. Tin nanoparticles as an effective conductive additive in silicon anodes

    PubMed Central

    Zhong, L.; Beaudette, C.; Guo, J.; Bozhilov, K.; Mangolini, L.

    2016-01-01

    We have found that the addition of tin nanoparticles to a silicon-based anode provides dramatic improvements in performance in terms of both charge capacity and cycling stability. Using a simple procedure and off-the-shelf additives and precursors, we developed a structure in which the tin nanoparticles are segregated at the interface between the silicon-containing active layer and the solid electrolyte interface. Even a minor addition of tin, as small as ∼2% by weight, results in a significant decrease in the anode resistance, as confirmed by electrochemical impedance spectroscopy. This leads to a decrease in charge transfer resistance, which prevents the formation of electrically inactive “dead spots” in the anode structure and enables the effective participation of silicon in the lithiation reaction. PMID:27484849

  10. The calculations of electromagnetic fields around nanoparticles embedded in biological media

    NASA Astrophysics Data System (ADS)

    Prytkova, Vera D.; Tuchin, Valery V.

    2010-08-01

    The goal of our project is to use computational methods, such as discrete dipole approximation (DDA) to study nanoparticles in biomedical photonics problems. Nanoparticle absorption and scattering are strongly affected by their shape, size, composition and dielectric environment. We focus on light scattering from nanoparticles embedded in biological or biocompatible media, such as water, glycerin and hemoglobin at erythrocyte hemoglobin concentration at concentration characteristic to intrinsic erythrocyte concentration. This method lets us consider complex refractive index of the nanoparticle and the surrounding medium as a function on the wavelength of light. We are interested in strong absorption and scattering around 800 nm that makes such nanoparticles potentially useful in biomedical applications, such as detection and curing cancer. Considering nanoparticles in living cells containing nanoparticles lets us understand light scattering from normal and pathological structures within biological tissue.

  11. Light absorption in silicon quantum dots embedded in silica

    SciTech Connect

    Mirabella, S.; Agosta, R.; Franzo, G.; Crupi, I.; Miritello, M.; Lo Savio, R.; Terrasi, A.; Di Stefano, M. A.; Di Marco, S.; Simone, F.

    2009-11-15

    The photon absorption in Si quantum dots (QDs) embedded in SiO{sub 2} has been systematically investigated by varying several parameters of the QD synthesis. Plasma-enhanced chemical vapor deposition (PECVD) or magnetron cosputtering (MS) have been used to deposit, upon quartz substrates, single layer, or multilayer structures of Si-rich-SiO{sub 2} (SRO) with different Si content (43-46 at. %). SRO samples have been annealed for 1 h in the 450-1250 deg. C range and characterized by optical absorption measurements, photoluminescence analysis, Rutherford backscattering spectrometry and x-ray Photoelectron Spectroscopy. After annealing up to 900 deg. C SRO films grown by MS show a higher absorption coefficient and a lower optical bandgap (approx2.0 eV) in comparison with that of PECVD samples, due to the lower density of Si-Si bonds and to the presence of nitrogen in PECVD materials. By increasing the Si content a reduction in the optical bandgap has been recorded, pointing out the role of Si-Si bonds density in the absorption process in small amorphous Si QDs. Both the photon absorption probability and energy threshold in amorphous Si QDs are higher than in bulk amorphous Si, evidencing a quantum confinement effect. For temperatures higher than 900 deg. C both the materials show an increase in the optical bandgap due to the amorphous-crystalline transition of the Si QDs. Fixed the SRO stoichiometry, no difference in the optical bandgap trend of multilayer or single layer structures is evidenced. These data can be profitably used to better implement Si QDs for future PV technologies.

  12. Preparation and Structural Analysis of CdS Nanoparticle Embedded Polyurethane Nanocomposites

    SciTech Connect

    Indolia, Ajay Pal; Kumar, Purushottam; Gaur, M. S.

    2011-07-15

    Polymer nanocomposite samples of different weight ratio of CdS were developed by solution embedding of nanoparticles in polyurethane. XRD and Scanning Electron Microscopy (SEM) were used to understand the structural properties of polymer nanocomposite samples. SEM micrograph demonstrates the dispersion of CdS nanoparticles in polymer matrix. It has been observed that crystallinity of PU decreases with increase in concentration of CdS nanoparticles. The XRD data show the characteristic peaks of nanoparticles (i.e.CdS) in nanocomposite samples, which confirm the nanostructure formation in polymer matrix.

  13. Epoxy and Silicone Optical Nanocomposites Filled with Grafted Nanoparticles

    NASA Astrophysics Data System (ADS)

    Tao, Peng

    Polymer nanocomposites, as a technologically important class of materials, exhibit diverse functional properties, and are used for applications ranging from structural and biomedical to electronic and optical. The properties of polymer nanocomposites are determined, in part, by the chemical composition of the polymer matrix and the nanofillers. Their properties are also sensitive to the geometry and size of the nanofillers, and to spatial distribution of the fillers. Control of the nanoparticle size and dispersion within a given polymer provides opportunities to tailor and optimize the properties of nanocomposites for specific application. For optical applications such as encapsulation of light emitting diodes (LEDs), polymer nanocomposites filled with homogeneously dispersed nanoparticles would endow the polymer encapsulant with new functionality without sacrificing optical transparency. To this end, this thesis focuses on developing a simple and versatile approach towards the fabrication of epoxy and silicone transparent nanocomposites using matrix compatible chain-grafted nanoparticles as fillers, and studying the optical properties of the nanocomposites. The surface chemistry and grafted polymer chain design have been shown to play an important role in determining the dispersion state of the grafted nanoparticles and hence the final optical properties of the nanocomposites. To prepare transparent epoxy nanocomposites, poly (glycidyl methacrylate) (PGMA) chains were grafted onto the optical nanoparticle surfaces via a combined phosphate ligand exchange process and azide-alkyne "click" chemistry. The dispersion behavior of PGMA-grafted nanoparticles within the epoxy matrix was investigated by systematically varying the grafting density and grafted chain length. It was found that within the small molecular weight epoxy resins, the dispersion states are more sensitive to the grafting density than the molecular weight of grafted chains. With high grafting densities

  14. Plasmon-assisted trapping of nanoparticles using a silver-nanowire-embedded PMMA nanofiber

    PubMed Central

    Cheng, Chang; Xu, Xiaohao; Lei, Hongxiang; Li, Baojun

    2016-01-01

    The integration of surface plasmon with waveguide is a strategy for lab-on-a-chip compatible optical trapping. Here, we report a method for trapping of nanoparticles using a silver nanowire (AgNW) embedded poly(methyl methacrylate) (PMMA) nanofiber with the assistance of surface plasmon polaritons (SPPs). The nanoparticles (polystyrene, 700 nm diameter) are transported along the nanofiber and ultimately trapped at the AgNW embedded region because of the enhanced optical gradient force towards the nanofiber exerted on the nanoparticles and optical potential well generated by the excitation of SPPs. The low optical power requirement and the easy fabrication of the AgNW-embedded nanofiber with broad range of wavelength for SPPs are advantageous to the applications in optofluidics and plasmofluidics. PMID:26843143

  15. Plasmon-assisted trapping of nanoparticles using a silver-nanowire-embedded PMMA nanofiber

    NASA Astrophysics Data System (ADS)

    Cheng, Chang; Xu, Xiaohao; Lei, Hongxiang; Li, Baojun

    2016-02-01

    The integration of surface plasmon with waveguide is a strategy for lab-on-a-chip compatible optical trapping. Here, we report a method for trapping of nanoparticles using a silver nanowire (AgNW) embedded poly(methyl methacrylate) (PMMA) nanofiber with the assistance of surface plasmon polaritons (SPPs). The nanoparticles (polystyrene, 700 nm diameter) are transported along the nanofiber and ultimately trapped at the AgNW embedded region because of the enhanced optical gradient force towards the nanofiber exerted on the nanoparticles and optical potential well generated by the excitation of SPPs. The low optical power requirement and the easy fabrication of the AgNW-embedded nanofiber with broad range of wavelength for SPPs are advantageous to the applications in optofluidics and plasmofluidics.

  16. Agglomeration of Luminescent Porous Silicon Nanoparticles in Colloidal Solutions.

    PubMed

    Herynková, Kateřina; Šlechta, Miroslav; Šimáková, Petra; Fučíková, Anna; Cibulka, Ondřej

    2016-12-01

    We have prepared colloidal solutions of clusters composed from porous silicon nanoparticles in methanol, water and phosphate-buffered saline (PBS). Even if the size of the nanoclusters is between 60 and 500 nm, due to their highly porous "cauliflower"-like structure, the porous silicon nanoparticles are composed of interconnected nanocrystals having around 2.5 nm in size and showing strong visible luminescence in the orange-red spectral region (centred at 600-700 nm). Hydrophilic behaviour and good solubility of the nanoclusters in water and water-based solutions were obtained by adding hydrogen peroxide into the etching solution during preparation and 16 min long after-bath in hydrogen peroxide. By simple filtration of the solutions with syringe filters, we have extracted smaller nanoclusters with sizes of approx. 60-70 nm; however, these nanoclusters in water and PBS solution (pH neutral) are prone to agglomeration, as was confirmed by zeta potential measurements. When the samples were left at ambient conditions for several weeks, the typical nanocluster size increased to approx. 330-400 nm and then remained stable. However, both freshly filtered and aged samples (with agglomerated porous silicon nanoparticles) of porous silicon in water and PBS solutions can be further used for biological studies or as luminescent markers in living cells. PMID:27541815

  17. Surface enhanced fluorescence of anti-tumoral drug emodin adsorbed on silver nanoparticles and loaded on porous silicon

    PubMed Central

    2012-01-01

    Fluorescence spectra of anti-tumoral drug emodin loaded on nanostructured porous silicon have been recorded. The use of colloidal nanoparticles allowed embedding of the drug without previous porous silicon functionalization and leads to the observation of an enhancement of fluorescence of the drug. Mean pore size of porous silicon matrices was 60 nm, while silver nanoparticles mean diameter was 50 nm. Atmospheric and vacuum conditions at room temperature were used to infiltrate emodin-silver nanoparticles complexes into porous silicon matrices. The drug was loaded after adsorption on metal surface, alone, and bound to bovine serum albumin. Methanol and water were used as solvents. Spectra with 1 μm spatial resolution of cross-section of porous silicon layers were recorded to observe the penetration of the drug. A maximum fluorescence enhancement factor of 24 was obtained when protein was loaded bound to albumin, and atmospheric conditions of inclusion were used. A better penetration was obtained using methanol as solvent when comparing with water. Complexes of emodin remain loaded for 30 days after preparation without an apparent degradation of the drug, although a decrease in the enhancement factor is observed. The study reported here constitutes the basis for designing a new drug delivery system with future applications in medicine and pharmacy. PMID:22748115

  18. Hybrid collagen-based hydrogels with embedded montmorillonite nanoparticles.

    PubMed

    Nistor, Manuela Tatiana; Vasile, Cornelia; Chiriac, Aurica P

    2015-08-01

    Montmorillonite nanoparticles have been physically incorporated within a crosslinked collagen/poly(N-isopropyl acrylamide) network in order to adjust the properties of the stimuli-responsive hybrid systems. The research underlines both the influence of hydrogel composition and nanoparticle type on hybrid hydrogel properties. The dispersion of the montmorillonite nanoparticles in polymeric matrix have been visualized by SEM, TEM and AFM techniques and quantitatively and qualitatively estimated using near infrared chemical imaging. The electrical charge of the nanoparticles influenced the polymeric chain arrangement and the pore size. The morphologies of the nanoparticulated layers are partially exfoliated or intercalated and uniformly dispersed through the polymeric semi-interpenetrated network based on collagen and poly(N-isopropyl acrylamide). The hybrid hydrogels exhibit pseudoplastic behavior and the addition of nanoparticles has resulted in the increase of the complex viscosity. The adhesion capacity was affected mainly by the presence of organically modified montmorillonites. PMID:26042709

  19. Silicon Nanoparticles as Amplifiers of the Ultrasonic Effect in Sonodynamic Therapy.

    PubMed

    Osminkina, L A; Kudryavtsev, A A; Zinovyev, S V; Sviridov, A P; Kargina, Yu V; Tamarov, K P; Nikiforov, V N; Ivanov, A V; Vasilyev, A N; Timoshenko, V Yu

    2016-06-01

    The possibility of using mesoporous silicon nanoparticles as amplifiers (sensitizers) of therapeutic ultrasonic exposure were studied experimentally in vitro and in vivo. The combination of nanoparticles and ultrasound led to a significant inhibition of Hep-2 cancer cell proliferation and Lewis lung carcinoma growth in mice. These results indicated good prospects of using silicon nanoparticles as sensitizers for sonodynamic therapy of tumors. PMID:27388631

  20. In-situ formation of nanoparticles within a silicon-based matrix

    DOEpatents

    Thoma, Steven G.; Wilcoxon, Jess P.; Abrams, Billie L.

    2008-06-10

    A method for encapsulating nanoparticles with an encapsulating matrix that minimizes aggregation and maintains favorable properties of the nanoparticles. The matrix comprises silicon-based network-forming compounds such as ormosils and polysiloxanes. The nanoparticles are synthesized from precursors directly within the silicon-based matrix.

  1. Strong and stable photoluminescence from sputtered silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Zhu, Y.; Wang, H.; Ong, P. P.

    2000-08-01

    Silicon nanoparticles have been prepared by means of direct dc sputtering of the silicon material onto the liquid nitrogen-cooled surface of the stainless-steel trap. By periodically harvesting the deposits followed by ultrasonic agitation in 2-propanol it was possible to produce nanometre-size silicon crystals of less than 10 nm in diameter, and in which the silicon particle surfaces were barely oxidized. XPS measurements of the samples so prepared revealed that the oxidization states of their surface layers were changed in different significant ways when the as-prepared sample was annealed in air or in a vacuum. However, all these chemical changes have very little effect on the photoluminescence level of the samples. Its intensity remains strong and stable in the region of 300-550 nm, both before and after annealing either in the atmosphere or in an ultra-high vacuum at up to 500 °C and for up to 6 h. Moreover, the photoluminescence intensity stays constant even after the samples were aged in the atmosphere at room temperature (300 K) for 22 days. The photoluminescence stability of our silicon nanoparticles, regardless of changes in their surface chemical structure, enhances their conduciveness for commercial applications.

  2. Gold nanoparticles embedded in organic/inorganic hybrid matrix: electrical and electrochemical behavior (withdrawal notice)

    NASA Astrophysics Data System (ADS)

    Moreira, Sandra D. F. C.; Silva, J. P. B.; Silva, Carlos J. R.; Capan, I.; Gomes, M. J. M.; Costa, Manuel F. M.

    2013-05-01

    Gold nanoparticles (AuNPs) with different diameters, from 3 to 32 nm, were immobilized in amine-alcohol-silicate matrix by mixing a preformed nanoparticle colloid with the precursors of amine-alcohol-silicate (AAs) prior to the solgel transition. These nanocomposites show high optical quality and optical features dictated by the size of the nanoparticle dopants but also present a high degree of flexibility which can largely enhance the range of practical applications. The current-voltage, impedance and capacitance-voltage characteristics of these materials have been measured. The electrochemical and impedimetric results reveal that AuNPs with different sizes give different signals, thus providing useful information that allows the employment of AuNPs in electrochemical biosensors. Capacitance- voltage measurements showed that these composites embedded AuNPs exhibited a large hysteresis window of 2.4V which indicates the possibility of charge storage in the Au nanoparticles embedded AAs hybrids.

  3. Characterizing structural and vibrational properties of nanoparticles embedded in silica with XAS, SAXS and auxiliary techniques

    SciTech Connect

    Araujo, Leandro L.; Kluth, Patrick; Giulian, Raquel; Sprouster, David J.; Ridgway, Mark C.; Johannessen, Bernt; Foran, Garry J.; Cookson, David J.

    2009-01-29

    Synchrotron-based techniques were combined with conventional analysis methods to probe in detail the structural and vibrational properties of nanoparticles grown in a silica matrix by ion implantation and thermal annealing, as well as the evolution of such properties as a function of nanoparticle size. This original approach was successfully applied for several elemental nanoparticles (Au, Co, Cu, Ge, Pt) and the outcomes for Ge are reported here, illustrating the power of this combined methodology. The thorough analysis of XANES, EXAFS, SAXS, TEM and Raman data for Ge nanoparticles with mean diameters between 4 and 9 nm revealed that the peculiar properties of embedded Ge nanoparticles, like the existence of amorphous Ge layers between the silica matrix and the crystalline nanoparticle core, are strongly dependent on particle size and mainly governed by the variation in the surface area-to-volume ratio. Such detailed information provides valuable input for the efficient planning of technological applications.

  4. Characterizing structural and vibrational properties of nanoparticles embedded in silica with XAS, SAXS and auxiliary techniques

    NASA Astrophysics Data System (ADS)

    Araujo, Leandro L.; Kluth, Patrick; Giulian, Raquel; Sprouster, David J.; Johannessen, Bernt; Foran, Garry J.; Cookson, David J.; Ridgway, Mark C.

    2009-01-01

    Synchrotron-based techniques were combined with conventional analysis methods to probe in detail the structural and vibrational properties of nanoparticles grown in a silica matrix by ion implantation and thermal annealing, as well as the evolution of such properties as a function of nanoparticle size. This original approach was successfully applied for several elemental nanoparticles (Au, Co, Cu, Ge, Pt) and the outcomes for Ge are reported here, illustrating the power of this combined methodology. The thorough analysis of XANES, EXAFS, SAXS, TEM and Raman data for Ge nanoparticles with mean diameters between 4 and 9 nm revealed that the peculiar properties of embedded Ge nanoparticles, like the existence of amorphous Ge layers between the silica matrix and the crystalline nanoparticle core, are strongly dependent on particle size and mainly governed by the variation in the surface area-to-volume ratio. Such detailed information provides valuable input for the efficient planning of technological applications.

  5. Heat-Induced Agglomeration of Amorphous Silicon Nanoparticles Toward the Formation of Silicon Thin Film.

    PubMed

    Jang, Bo Yun; Kim, Ja Young; Seo, Gyeongju; Shin, Chae-Ho; Ko, Chang Hyun

    2016-01-01

    The thermal behavior of silicon nanoparticles (Si NPs) was investigated for the preparation of silicon thin film using a solution process. TEM analysis of Si NPs, synthesized by inductively coupled plasma, revealed that the micro-structure of the Si NPs was amorphous and that the Si NPs had melted and merged at a comparatively low temperature (~750 °C) considering bulk melting temperature of silicon (1414 °C). A silicon ink solution was prepared by dispersing amorphous Si NPs in propylene glycol (PG). It was then coated onto a silicon wafer and a quartz plate to form a thin film. These films were annealed in a vacuum or in an N₂ environment to increase their film density. N2 annealing at 800 °C and 1000 °C induced the crystallization of the amorphous thin film. An elemental analysis by the SIMS depth profile showed that N₂annealing at 1000 °C for 180 min drastically reduced the concentrations of carbon and oxygen inside the silicon thin film. These results indicate that silicon ink prepared using amorphous Si NPs in PG can serve as a proper means of preparing silicon thin film via solution process. PMID:27398566

  6. Multilayer structures of silicon-suboxide embedded in single crystal silicon

    NASA Astrophysics Data System (ADS)

    Pohl, Christoph; Raab, Nicolas; Mitterer, Martin; Tarakina, Nadezda; Breuer, Uwe; Brunner, Karl

    2014-03-01

    Si/SiOx multilayer structures with ultra-thin silicon-suboxide layers are fabricated with molecular beam epitaxy. The silicon surface is oxidized during growth interruptions at an oxygen pressure between 1.0×10-7 mbar and 8.0×10-7 mbar. Overgrowth with Si of the oxidized surface is possible for coverages of a few monolayers of O and improves with increasing substrate temperature. X-ray diffraction shows that the silicon layers are single crystalline. Transmission electron microscopy measurements show that the suboxide layers are ~1 nm thick, pseudomorph, and exhibit crystalline order throughout the layer. In addition, transmission electron microscopy shows that the oxygen concentration is laterally inhomogeneous. The multilayer structures are thermally very stable, as rapid thermal annealing up to 1000 °C shows no influence on the X-ray diffraction patterns.

  7. Photoconductivity of organic polymer films doped with porous silicon nanoparticles and ionic polymethine dyes

    SciTech Connect

    Davidenko, N. A. Skrichevsky, V. A.; Ishchenko, A. A.; Karlash, A. Yu.; Mokrinskaya, E. V.

    2009-05-15

    Features of electrical conductivity and photoconductivity of polyvinylbutyral films containing porous silicon nanoparticles and similar films doped with cationic and anionic polymethine dyes are studied. Sensitization of the photoelectric effect by dyes with different ionicities in films is explained by the possible photogeneration of holes and electrons from dye molecules and the intrinsic bipolar conductivity of porous silicon nanoparticles. It is assumed that the electronic conductivity in porous silicon nanoparticles is higher in comparison with p-type conductivity.

  8. Fluorescence of silicon nanoparticles prepared by nanosecond pulsed laser

    SciTech Connect

    Liu, Chunyang Sui, Xin; Yang, Fang; Ma, Wei; Li, Jishun; Xue, Yujun; Fu, Xing

    2014-03-15

    A pulsed laser fabrication method is used to prepare fluorescent microstructures on silicon substrates in this paper. A 355 nm nanosecond pulsed laser micromachining system was designed, and the performance was verified and optimized. Fluorescence microscopy was used to analyze the photoluminescence of the microstructures which were formed using the pulsed laser processing technique. Photoluminescence spectra of the microstructure reveal a peak emission around 500 nm, from 370 nm laser irradiation. The light intensity also shows an exponential decay with irradiation time, which is similar to attenuation processes seen in porous silicon. The surface morphology and chemical composition of the microstructure in the fabricated region was also analyzed with multifunction scanning electron microscopy. Spherical particles are produced with diameters around 100 nm. The structure is compared with porous silicon. It is likely that these nanoparticles act as luminescence recombination centers on the silicon surface. The small diameter of the particles modifies the band gap of silicon by quantum confinement effects. Electron-hole pairs recombine and the fluorescence emission shifts into the visible range. The chemical elements of the processed region are also changed during the interaction between laser and silicon. Oxidation and carbonization play an important role in the enhancement of fluorescence emission.

  9. Experimental investigations of quantum confined silicon nanoparticle light emitting devices

    NASA Astrophysics Data System (ADS)

    Ligman, Rebekah Kristine

    2007-12-01

    As the demands on our world's energy resources continue to grow, alternative high efficiency materials such as quantum confined silicon nanoparticles (Si nps) are desirable for their potential low cost application in white light illumination, in optical displays, and in on-chip optical interconnects. Many fabrication and passivation techniques exist that produce Si nps with high photogenerated quantum yield. However, high electrically generated Si np quantum efficiency has eluded our society. Predominantly due to the lack of a stable surface passivation and a device fabrication technique that preserves the Si np optical properties. To amend these deficiencies, the passivation of nonthermal plasma fabricated Si nps with a surface oxide grown under UV exposure was first investigated. Control over the surface oxidized Si np (Si/SiO2) passivation growth was demonstrated and the optical stability of Si/SiO2 nps was suitable for demonstrating Si np electroluminescence (EL). Two approaches for constructing hybrid organic light emitting diode (OLED) devices around nonthermal plasma fabricated Si nps were then investigated. Multilayer devices, composed of a nonthermal plasma fabricated Si np layer embedded within an OLED, were first studied. However, no EL from Si nps was obtained using the multilayer device architecture due to poor control over the Si np film thickness. Single layer polymer(Si/SiO2) hybrid devices, composed of nps randomly dispersed within an extrinsic conductive polymer, were then studied and EL from Si/SiO2 nps was obtained. The hybrid device optical and electrical response was enhanced over the control devices, possibly due to morphology changes induced by the Si/SiO2 nps. The energy transfer (ET) processes in single layer polymer(Si/SiO 2) hybrid devices were then investigated by imposing known spatial separations between the intrinsic conductive polymers and Si/SiO2 nps. No measurable Si/SiO2 np emission was observed from the intrinsic hybrid devices

  10. Morphology and aspect ratio of bismuth nanoparticles embedded in a zinc matrix

    SciTech Connect

    Song, Tae Eun; Wilde, Gerhard; Peterlechner, Martin

    2014-12-15

    Nanoscale Bi particles embedded in a Zn matrix were obtained by casting and melt-spinning, resulting in quenching rate-dependent sizes and shapes. With decreasing Bi particle size, an increasing aspect ratio was observed. Due to high resolution transmission electron microscopy performed for different orientations of the nanoparticles and the matrix, the three-dimensional shape and the respective crystallographic orientations of the Bi nanoparticles as well as the orientation relationship with the matrix have been evaluated. It is suggested that the size-dependence of the nanoparticle morphologies has a strong impact on their thermal stabilities thus affecting the size dependence of the melting temperature.

  11. Driving degradation within biodegradable polymers with embedded nanoparticles

    NASA Astrophysics Data System (ADS)

    Gorga, Russell; Firestone, Gabriel; Fontecha, Daniela; Bochinski, Jason; Clarke, Laura

    The ability to controllably trigger breaking of chemical bonds enables a substance that has robust material properties during use but can be re-worked or deteriorated upon command. Photothermal heating creates intense local heat at isolated nanoparticle locations within a sample and can result in very different material responses than those achievable with conventional (uniform) heating. In this process, irradiation with visible light resonant with the nanoparticle's surface plasmon resonance results in dramatic local heating of the particles and the surrounding material. This work studies intentional thermal degradation of poly ethyl cyanoacrylate-starch composites doped with metal nanoparticles, and explores differences in degradation speed, efficiency, and resultant mechanical properties when heated via the photothermal effect. This work was supported by the National Science Foundation, Grant #: CMMI-1462966.

  12. Silicon nanoparticles as a luminescent label to DNA.

    PubMed

    Wang, L; Reipa, V; Blasic, J

    2004-01-01

    We successfully conjugated 1-2 nm diameter silicon nanoparticles to a 5'-amino-modified oligonucleotide (60mer) that contains a C6 linker between amide and phosphate groups. The conjugation was implemented via two photoinduced reactions followed by a DNA labeling step through formation of a carboxamide bond. Photoluminescence of the conjugates is dominated by two blue bands (400 and 450 nm maximal) under 340 nm excitation. The quantum yield of oligonucleotide-conjugated nanoparticles was determined to be 0.08 as measured against quinine sulfate in 0.1 M HClO(4) as a reference standard. We report a conjugation process that allows labeling of Si nanoparticles to an oligonucleotide in aqueous solutions. Ways to further optimize the procedure in order to achieve narrower and brighter photoluminescence are discussed. PMID:15025539

  13. Controlled delivery of acyclovir from porous silicon micro- and nanoparticles

    NASA Astrophysics Data System (ADS)

    Maniya, Nalin H.; Patel, Sanjaykumar R.; Murthy, Z. V. P.

    2015-03-01

    In this work, micro- and nanoparticles of porous silicon (PSi) are demonstrated to act as effective carrier for the controlled delivery of acyclovir (ACV). PSi films prepared by electrochemical etching were fractured by ultrasonication to prepare micro- and nanoparticles. PSi native particles were thermally oxidized (TOPSi) and thermally hydrosilylated using undecylenic acid (UnPSi). PSi particles with three different surface chemistries were then loaded with ACV by physical adsorption and covalent attachment. Such particles were characterized by scanning electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. In vitro ACV release experiments in phosphate buffered saline showed sustained release behaviour from both micro- and nanoparticles and order of release was found to be native PSi > TOPSi > UnPSi. Drug release kinetics study using Korsmeyer-Peppas model suggested a combination of both drug diffusion and Si scaffold erosion based drug release mechanisms.

  14. Optical bistability in plasmonic nanoparticles: Effect of size, shape and embedding medium

    NASA Astrophysics Data System (ADS)

    Daneshfar, Nader; Foroughi, Hamidreza

    2016-09-01

    We theoretically investigate the optical bistability, which one input signal allows two possible outputs, from single spherical/cylindrical nanoparticles and also nanoshells in the frame work of quasi-static formalism. It is shown that the bistability behavior greatly depends on several parameters such as the nanoparticle size, material and the surrounding dielectric environment. We demonstrated the width of the bistability region and also the bistable threshold depends on the geometrical parameters, and can be tuned by adjusting the size of nanoparticle, the shell thickness and the dielectric constant of the embedding medium. It is also shown that the optical bistable behavior depends strongly on the shape of plasmonic nanoparticles and nanoshells. However, these dependences of optical bistability of spherical/cylindrical nanoparticles and nanoshells on changing of their geometrical parameters can be used for realize optical switching and sensing purposes.

  15. Magnetic anisotropy of embedded Co nanoparticles: Influence of the surrounding matrix

    NASA Astrophysics Data System (ADS)

    Tamion, Alexandre; Raufast, Cécile; Hillenkamp, Matthias; Bonet, Edgar; Jouanguy, J.; Canut, Bruno; Bernstein, Estella; Boisron, Olivier; Wernsdorfer, Wolfgang; Dupuis, Véronique

    2010-04-01

    We report on the magnetic properties of Co clusters embedded in four different matrices (Ag, Au, Si, and amorphous carbon). The recently developed “triple fit” method for treating conventional magnetometry data allows, together with micro-superconducting quantum interference device ( μ -SQUID) investigations, the detailed study of the influence of the surrounding matrix on the magnetic volume and the magnetic anisotropy of Co nanoparticles. While interdiffusion between matrix and Co atoms cannot be excluded in Si and amorphous C matrices, the structure of clusters embedded in the metallic matrices remains intact. Ag and Au matrices increase significantly the magnetic anisotropy energy of the Co clusters. μ -SQUID experiments indicate that the magnetic anisotropy of embedded clusters is not affected by a magnetically dead layer and that an anisotropy dispersion must be taken into account for size-selected nanoparticles.

  16. Thermally activated tunneling in porous silicon nanowires with embedded Si quantum dots

    NASA Astrophysics Data System (ADS)

    Rezvani, S. J.; Pinto, N.; Enrico, E.; D'Ortenzi, L.; Chiodoni, A.; Boarino, L.

    2016-03-01

    Electronic transport properties of porous Si nanowires either with embedded Si quantum dots or with a percolative crystalline path are studied as a function of the temperature for the first time. We show that unlike bulk porous Si, the predesigned structure of the wires results in a single distinct conduction mechanism such as tunneling in the former case and variable range hopping in the latter case. We demonstrate that the geometry of the systems with a large internal surface area and high density of the Si quantum dots have a significant conduction enhancement compared to bulk porous silicon. These results can also improve the understanding of the basis of the different electronic transport mechanisms reported in bulk porous silicon.

  17. Fabrication of parylene channels embedded in silicon using a single parylene deposition step

    NASA Astrophysics Data System (ADS)

    Tolstosheeva, Elena; Pimentel, João. V.; Schander, Andreas; Kempen, Ludger; Vellekoop, Michael; Lang, Walter

    2015-06-01

    In-situ integration of microfluidic channels into the microfabrication process flow of implantable microsystems is desirable, for example to enable efficient drug delivery. We propose a fabrication method for such microfluidic channels using parylene C, a biocompatible material whose inert nature favours water flow. A single deposition of parylene C enabled monolithical integration of fully-sealed micro-channels in a silicon substrate. The channel geometry was predefined by etching 100 μm-deep grooves into a silicon substrate. A PVC foil was fixed manually on the wafer and served as a top-cover for the grooves. The wafers were coated with the adhesion promoter AdPro Poly® and a 15 μm-thick parylene C film was deposited conformally into the grooves-foil enclosed space. The outgasing nature of the PVC foil hindered the adhesion of parylene C, allowing the foil to be peeled off easily from the parylene surface. The functionality of the fully-sealed parylene channels, embedded in the silicon wafer, was verified by injecting DI water with dispersed polystyrene microbeads (diameter 6 μm): the polystyrene beads were successfully transported along the channel. Further, a fully-sealed parylene chamber remained leak-tight throughout a stepwise application of hydrostatic pressures from 0.2 to 3.0 bar (15 s step-interval). In short, our parylene channels are: (1) suitable for microsystem drug-delivery; (2) in-situ enclosed hollow spaces embedded in the silicon substrate, realized with a single parylene deposition; (3) intact at hydrostatic pressures up to 3 bar.

  18. Dielectric silicone elastomers with mixed ceramic nanoparticles

    SciTech Connect

    Stiubianu, George; Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian; Ignat, Mircea

    2015-11-15

    Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

  19. Tunneling Anisotropic Magnetoresistance in Fe Nanoparticles Embedded in MgO Matrix

    NASA Astrophysics Data System (ADS)

    Pham, T. V.; Miwa, S.; Suzuki, Y.

    2016-05-01

    The tunnel magnetoresistance (TMR) effect is related to the relative orientation of the magnetizations of the two ferromagnetic electrodes in magnetic tunnel junctions (MTJs). The tunnel anisotropic magnetoresistance (TAMR) effect is related to the orientation of the magnetization with respect to the current direction or the crystallographic axes. Beyond the TMR, the TAMR is not only present in MTJs in which both electrodes are ferromagnetic but may also appear in tunnel structures with a single magnetic electrode. We investigated the magnetotransport properties in an Au/MgO/Fe nanoparticles/MgO/Cu tunnel junction. We found that both the TMR and TAMR can appear in tunnel junctions with Fe nanoparticles embedded in an MgO matrix. The TMR is attributed to spin-dependent tunneling between Fe nanoparticles, so the device resistance depends on the magnetization directions of adjacent Fe nanoparticles. The TAMR is attributed to the interfacial spin-orbit interaction, so the device resistance depends on each magnetization direction of an Fe nanoparticle. This is the first observation of the TAMR in Fe nanoparticles embedded in an MgO matrix.

  20. Optoelectronic device with nanoparticle embedded hole injection/transport layer

    DOEpatents

    Wang, Qingwu; Li, Wenguang; Jiang, Hua

    2012-01-03

    An optoelectronic device is disclosed that can function as an emitter of optical radiation, such as a light-emitting diode (LED), or as a photovoltaic (PV) device that can be used to convert optical radiation into electrical current, such as a photovoltaic solar cell. The optoelectronic device comprises an anode, a hole injection/transport layer, an active layer, and a cathode, where the hole injection/transport layer includes transparent conductive nanoparticles in a hole transport material.

  1. Synthesis and characterization of magnetic nanoparticles embedded in polyacrylonitrile nanofibers

    NASA Astrophysics Data System (ADS)

    Munteanu, Daniel; Ion, Rodica-Mariana; Cocina, George-Costel

    2010-11-01

    Nanomedicine is defined as the monitoring, repair, construction, and control of human biological systems at the molecular level using engineered nanodevices and nanostructures. Polyacrylonitrile (PAN) solution containing the iron oxide precursor iron (III) was electrospun and thermally treated to produce electrically conducting, magnetic carbon nanofiber mats with hierarchical pore structures. This paper discusses the synthesis of magnetite (Fe3O4) nanoparticles with mean crystallite size of 10 nm with polyacrylonitrile (PAN) as the protecting agent, creating nanofiber. The morphology and material properties of the resulting multifunctional nanofiber including the surface area were examined using various characterization techniques. Optical microscopy images show that uniform fibers were produced with a fiber diameter of ~600 nm, and this uniform fiber morphology is maintained after graphitization with a fiber diameter of ~330 nm. X-ray diffraction (XRD) studies reveal the size of Fe3O4 crystals. A combination of XRD and electron microscopy experiments reveals the formation of pores with graphitic nanoparticles in the walls as well as the formation of magnetite nanoparticles distributed throughout the fibers.

  2. Thermodynamics of a phase transition of silicon nanoparticles at the annealing and carbonization of porous silicon

    SciTech Connect

    Nagornov, Yu. S.

    2015-12-15

    The formation of SiC nanocrystals of the cubic modification in the process of high-temperature carbonization of porous silicon has been analyzed. A thermodynamic model has been proposed to describe the experimental data obtained by atomic-force microscopy, Raman scattering, spectral analysis, Auger spectroscopy, and X-ray diffraction spectroscopy. It has been shown that the surface energy of silicon nanoparticles and quantum filaments is released in the process of annealing and carbonization. The Monte Carlo simulation has shown that the released energy makes it possible to overcome the nucleation barrier and to form SiC nanocrystals. The processes of laser annealing and electron irradiation of carbonized porous silicon have been analyzed.

  3. Enhanced Multiple Exciton Generation in Amorphous Silicon Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kryjevski, Andrei; Mihaylov, Deyan; Kilin, Dmitri

    2015-03-01

    Multiple exciton generation (MEG) in nm-sized hydrogen-passivated silicon nanowires (NWs), and quasi two-dimensional nanofilms depends strongly on the degree of the core structural disorder as shown by the many-body perturbation theory (MBPT) calculations based on the DFT simulations. Here, we use the HSE exchange correlation functional. In MBPT, we work to the 2nd order in the electron-photon coupling and in the approximate screened Coulomb interaction. We also include the effect of excitons for which we solve Bethe-Salpeter Equation. We calculate quantum efficiency (QE), the average number of excitons created by a single absorbed photon, in 3D arrays of Si29H36 quantum dots, NWs, and quasi 2D silicon nanofilms, all with both crystalline and amorphous core structures. Efficient MEG with QE of 1.3 up to 1.8 at the photon energy of about 3Eg , where Eg is the gap, is predicted in these nanoparticles except for the crystalline NW and film where QE ~= 1 . MEG in the amorphous nanoparticles is enhanced by the electron localization due to structural disorder. The exciton effects significantly red-shift QE (Ephoton) curves. Nanometer-sized amorphous silicon NWs and films are predicted to have effective MEG within the solar spectrum range. We acknowledge NSF support (CHE-1413614) for method development.

  4. Frequency-Dependent Magnetic Susceptibility of Magnetite and Cobalt Ferrite Nanoparticles Embedded in PAA Hydrogel

    PubMed Central

    van Berkum, Susanne; Dee, Joris T.; Philipse, Albert P.; Erné, Ben H.

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

  5. Frequency-dependent magnetic susceptibility of magnetite and cobalt ferrite nanoparticles embedded in PAA hydrogel.

    PubMed

    van Berkum, Susanne; Dee, Joris T; Philipse, Albert P; Erné, Ben H

    2013-01-01

    Chemically responsive hydrogels with embedded magnetic nanoparticles are of interest for biosensors that magnetically detect chemical changes. A crucial point is the irreversible linkage of nanoparticles to the hydrogel network, preventing loss of nanoparticles upon repeated swelling and shrinking of the gel. Here, acrylic acid monomers are adsorbed onto ferrite nanoparticles, which subsequently participate in polymerization during synthesis of poly(acrylic acid)-based hydrogels (PAA). To demonstrate the fixation of the nanoparticles to the polymer, our original approach is to measure low-field AC magnetic susceptibility spectra in the 0.1 Hz to 1 MHz range. In the hydrogel, the magnetization dynamics of small iron oxide nanoparticles are comparable to those of the particles dispersed in a liquid, due to fast Néel relaxation inside the particles; this renders the ferrogel useful for chemical sensing at frequencies of several kHz. However, ferrogels holding thermally blocked iron oxide or cobalt ferrite nanoparticles show significant decrease of the magnetic susceptibility resulting from a frozen magnetic structure. This confirms that the nanoparticles are unable to rotate thermally inside the hydrogel, in agreement with their irreversible fixation to the polymer network. PMID:23673482

  6. Fully Tunable Silicon Nanowire Arrays Fabricated by Soft Nanoparticle Templating.

    PubMed

    Rey, By Marcel; Elnathan, Roey; Ditcovski, Ran; Geisel, Karen; Zanini, Michele; Fernandez-Rodriguez, Miguel-Angel; Naik, Vikrant V; Frutiger, Andreas; Richtering, Walter; Ellenbogen, Tal; Voelcker, Nicolas H; Isa, Lucio

    2016-01-13

    We demonstrate a fabrication breakthrough to produce large-area arrays of vertically aligned silicon nanowires (VA-SiNWs) with full tunability of the geometry of the single nanowires and of the whole array, paving the way toward advanced programmable designs of nanowire platforms. At the core of our fabrication route, termed "Soft Nanoparticle Templating", is the conversion of gradually compressed self-assembled monolayers of soft nanoparticles (microgels) at a water-oil interface into customized lithographical masks to create VA-SiNW arrays by means of metal-assisted chemical etching (MACE). This combination of bottom-up and top-down techniques affords excellent control of nanowire etching site locations, enabling independent control of nanowire spacing, diameter and height in a single fabrication route. We demonstrate the fabrication of centimeter-scale two-dimensional gradient photonic crystals exhibiting continuously varying structural colors across the entire visible spectrum on a single silicon substrate, and the formation of tunable optical cavities supported by the VA-SiNWs, as unambiguously demonstrated through numerical simulations. Finally, Soft Nanoparticle Templating is combined with optical lithography to create hierarchical and programmable VA-SiNW patterns. PMID:26672801

  7. Matrix and interaction effects on the magnetic properties of Co nanoparticles embedded in gold and vanadium.

    PubMed

    Ruano, M; Díaz, M; Martínez, L; Navarro, E; Román, E; García-Hernandez, M; Espinosa, A; Ballesteros, C; Fermento, R; Huttel, Y

    2013-01-01

    The study of the magnetic properties of Co nanoparticles (with an average diameter of 10.3 nm) grown using a gas-phase aggregation source and embedded in Au and V matrices is presented. We investigate how the matrix, the number of embedded nanoparticles (counted by coverage percentage), the interparticle interactions and the complex nanoparticles/matrix interface structure define the magnetic properties of the studied systems. A threshold coverage of 3.5% of a monolayer was found in both studied systems: below this coverage, nanoparticles behave as an assembly of independent single-domain magnetic entities with uniaxial anisotropy. Above the threshold it is found that the magnetic behavior of the systems is more matrix dependent. While magnetic relaxation and Henkel plots measurements stress the importance of the dipolar interactions and the formation of coherent clusters in the case of the Au matrix, the magnetic behavior of cobalt clusters embedded in the vanadium matrix is explained through the formation of a spin glass-like state at the V-Co interface that screens the magnetic interactions between NPs. PMID:23165521

  8. Cotunneling enhancement of magnetoresistance in double magnetic tunnel junctions with embedded superparamagnetic NiFe nanoparticles

    NASA Astrophysics Data System (ADS)

    Dempsey, K. J.; Hindmarch, A. T.; Wei, H.-X.; Qin, Q.-H.; Wen, Z.-C.; Wang, W.-X.; Vallejo-Fernandez, G.; Arena, D. A.; Han, X.-F.; Marrows, C. H.

    2010-12-01

    Temperature and bias voltage-dependent transport characteristics are presented for double magnetic tunnel junctions (DMTJs) with self-assembled NiFe nanoparticles embedded between insulating alumina barriers. The junctions with embedded nanoparticles are compared to junctions with a single barrier of comparable size and growth conditions. The embedded particles are characterized using x-ray absorption spectroscopy, transmission electron microscopy, and magnetometry techniques, showing that they are unoxidized and remain superparamagnetic to liquid helium temperatures. The tunneling magnetoresistance (TMR) for the DMTJs is lower than the control samples, however, for the DMTJs an enhancement in TMR is seen in the Coulomb blockade region. Fitting the transport data in this region supports the theory that cotunneling is the dominant electron transport process within the Coulomb blockade region, sequential tunneling being suppressed. We therefore see an enhanced TMR attributed to the change in the tunneling process due to the interplay of the Coulomb blockade and spin-dependent tunneling through superparamagnetic nanoparticles, and develop a simple model to quantify the effect, based on the fact that our nanoparticles will appear blocked when measured on femtosecond tunneling time scales.

  9. Anisotropic effective medium properties from interacting Ag nanoparticles in silicon dioxide.

    PubMed

    Menegotto, Thiago; Horowitz, Flavio

    2014-05-01

    Films containing a layer of Ag nanoparticles embedded in silicon dioxide were produced by RF magnetron sputtering. Optical transmittance measurements at several angles of incidence (from normal to 75°) revealed two surface plasmon resonance (SPR) peaks, which depend on electric field direction: one in the ultraviolet and another red-shifted from the dilute Ag/SiO₂ system resonance at 410 nm. In order to investigate the origin of this anisotropic behavior, the structural properties were determined by transmission electron microscopy, revealing the bidimensional plane distribution of Ag nanoparticles with nearly spherical shape as well as the filling factor of metal in the composite. A simple model linked to these experimental parameters allowed description of the most relevant features of the SPR positions, which, depending on the field direction, were distinctly affected by the coupling of oscillations between close nanoparticles, as described by a modified Drude-Lorentz dielectric function introduced into the Maxwell-Garnett relation. This approach allowed prediction of the resonance for light at 75° incidence from the SPR position for light at normal incidence, in good agreement with experimental observation. PMID:24921871

  10. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate

    NASA Astrophysics Data System (ADS)

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Hasan, Shakeeb Bin; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic 84Kr and 197Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm-1 in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles.

  11. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate.

    PubMed

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Bin Hasan, Shakeeb; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic (84)Kr and (197)Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm(-1) in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles. PMID:26902734

  12. Nanofibrillated Cellulose and Copper Nanoparticles Embedded in Polyvinyl Alcohol Films for Antimicrobial Applications

    PubMed Central

    Zhong, Tuhua; Oporto, Gloria S.; Jaczynski, Jacek; Jiang, Changle

    2015-01-01

    Our long-term goal is to develop a hybrid cellulose-copper nanoparticle material as a functional nanofiller to be incorporated in thermoplastic resins for efficiently improving their antimicrobial properties. In this study, copper nanoparticles were first synthesized through chemical reduction of cupric ions on TEMPO nanofibrillated cellulose (TNFC) template using borohydride as a copper reducing agent. The resulting hybrid material was embedded into a polyvinyl alcohol (PVA) matrix using a solvent casting method. The morphology of TNFC-copper nanoparticles was analyzed by transmission electron microscopy (TEM); spherical copper nanoparticles with average size of 9.2 ± 2.0 nm were determined. Thermogravimetric analysis and antimicrobial performance of the films were evaluated. Slight variations in thermal properties between the nanocomposite films and PVA resin were observed. Antimicrobial analysis demonstrated that one-week exposure of nonpathogenic Escherichia coli DH5α to the nanocomposite films results in up to 5-log microbial reduction. PMID:26137482

  13. Electric bistability in pentacene film-based transistor embedding gold nanoparticles.

    PubMed

    Tseng, Chiao-Wei; Tao, Yu-Tai

    2009-09-01

    Pentacene films were deposited on a silica surface decorated with gold nanoparticles (Au-NPs). The crystallinity and packing orientation of the film are critically dependent on the surface properties of the nanoparticles, which can be tuned by a self-assembled monolayer (SAM) of organic thiolate on the nanoparticles. High-performance field-effect transistors based on the Au-NPs-embedded pentacene films can be prepared if the nanoparticles are made "hydrophobic" as well as "oleophobic" by appropriate SAMs. Electrical bistability was observed in these devices, with a memory window that depends on the size and surface modification of the Au-NPs. The structural characterization and electronic characteristics of the devices will be detailed. PMID:19655797

  14. Porous silicon nanoparticles for cancer photothermotherapy

    NASA Astrophysics Data System (ADS)

    Hong, Chanseok; Lee, Jungkeun; Zheng, Hongmei; Hong, Soon-Sun; Lee, Chongmu

    2011-12-01

    The in vitro cell tests and in vivo animal tests were performed to investigate the feasibility of the photothermal therapy based on porous silicon (PSi) in combination with near-infrared (NIR) laser. According to the Annexin V- fluorescein isothiocyanate Apoptosis assay test results, the untreated cells and the cells exposed to NIR laser without PSi treatment had a cell viability of 95.6 and 91.3%, respectively. Likewise, the cells treated with PSi but not with NIR irradiation also had a cell viability of 74.4%. Combination of these two techniques, however, showed a cell viability of 6.7%. Also, the cell deaths were mostly due to necrosis but partly due to late apoptosis. The in vivo animal test results showed that the Murine colon carcinoma (CT-26) tumors were completely resorbed without nearly giving damage to surrounding healthy tissue within 5 days of PSi and NIR laser treatment. Tumors have not recurred at all in the PSi/NIR treatment groups thereafter. Both the in vitro cell test and in vivo animal test results suggest that thermotherapy based on PSi in combination with NIR laser irradiation is an efficient technique to selectively destroy cancer cells without damaging the surrounding healthy cells.

  15. Subsurface Synthesis and Characterization of Ag Nanoparticles Embedded in MgO

    SciTech Connect

    Vilayur Ganapathy, Subramanian; Devaraj, Arun; Colby, Robert J.; Pandey, Archana; Varga, Tamas; Shutthanandan, V.; Manandhar, Sandeep; El-Khoury, Patrick Z.; Kayani, Asghar N.; Hess, Wayne P.; Thevuthasan, Suntharampillai

    2013-03-08

    Metal nanoparticles exhibit localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the dielectric medium surrounding it. LSPR causes field enhancement near the surface of the nanoparticle making them interesting candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix form hotspots which are prime locations for LSPR spectroscopy and sensing. This study involves synthesizing partially buried Ag nanoparticles in MgO and investigating the characteristics of this material system. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 10000C for 10 and 30 hours. A detailed optical and structural characterization was carried out to understand the evolution of Ag nanoparticle microstructure and size distribution inside the MgO matrix. Micro x-ray diffraction (MicroXRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes as seen from aberration corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

  16. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO.

    PubMed

    Vilayurganapathy, S; Devaraj, A; Colby, R; Pandey, A; Varga, T; Shutthanandan, V; Manandhar, S; El-Khoury, P Z; Kayani, Asghar; Hess, W P; Thevuthasan, S

    2013-03-01

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag(+) ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles. PMID:23403363

  17. Subsurface synthesis and characterization of Ag nanoparticles embedded in MgO

    NASA Astrophysics Data System (ADS)

    Vilayurganapathy, S.; Devaraj, A.; Colby, R.; Pandey, A.; Varga, T.; Shutthanandan, V.; Manandhar, S.; El-Khoury, P. Z.; Kayani, Asghar; Hess, W. P.; Thevuthasan, S.

    2013-03-01

    Metal nanoparticles exhibit a localized surface plasmon resonance (LSPR) which is very sensitive to the size and shape of the nanoparticle and the surrounding dielectric medium. The coupling between the electromagnetic radiation and the localized surface plasmon in metallic nanoparticles results in a sizable enhancement of the incident fields, making them possible candidates for plasmonic applications. In particular, partially exposed metallic nanoparticles distributed in a dielectric matrix can provide prime locations for LSPR spectroscopy and sensing. We report the synthesis and characterization of a plasmonic substrate consisting of Ag nanoparticles partially buried in MgO. Ag nanoparticles of different shapes and size distributions were synthesized below the surface of MgO by implanting 200 keV Ag+ ions followed by annealing at 1000 °C for 10 and 30 h. A detailed optical and structural characterization was carried out to understand the evolution of the Ag nanoparticle and size distribution inside the MgO matrix. Micro x-ray diffraction (Micro-XRD) was employed to investigate the structural properties and estimate the crystallite size. The nanoparticles evolved from a spherical to a faceted morphology with annealing time, assuming an octahedral shape truncated at the (001) planes, as visualized from aberration-corrected transmission electron microscopy (TEM) images. The nanoparticles embedded in MgO were shown to be pure metallic Ag using atom probe tomography (APT). The nanoparticles were partially exposed to the surface by employing plasma etch techniques to remove the overlaying MgO. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were employed to study the surface morphology and obtain a height distribution for the partially exposed nanoparticles.

  18. Self assembly of magnetic nanoparticles at silicon surfaces.

    PubMed

    Theis-Bröhl, Katharina; Gutfreund, Philipp; Vorobiev, Alexei; Wolff, Max; Toperverg, Boris P; Dura, Joseph A; Borchers, Julie A

    2015-06-21

    Neutron reflectometry was used to study the assembly of magnetite nanoparticles in a water-based ferrofluid close to a silicon surface. Under three conditions, static, under shear and with a magnetic field, the depth profile is extracted. The particles have an average diameter of 11 nm and a volume density of 5% in a D2O-H2O mixture. They are surrounded by a 4 nm thick bilayer of carboxylic acid for steric repulsion. The reflectivity data were fitted to a model using a least square routine based on the Parratt formalism. From the scattering length density depth profiles the following behavior is concluded: the fits indicate that excess carboxylic acid covers the silicon surface and almost eliminates the water in the densely packed wetting layer that forms close to the silicon surface. Under constant shear the wetting layer persists but a depletion layer forms between the wetting layer and the moving ferrofluid. Once the flow is stopped, the wetting layer becomes more pronounced with dense packing and is accompanied by a looser packed second layer. In the case of an applied magnetic field the prolate particles experience a torque and align with their long axes along the silicon surface which leads to a higher particle density. PMID:25971712

  19. Room temperature NO2-sensing properties of WO3 nanoparticles/porous silicon

    NASA Astrophysics Data System (ADS)

    Yan, Wenjun; Hu, Ming; Zeng, Peng; Ma, Shuangyun; Li, Mingda

    2014-02-01

    WO3 nanoparticles were synthesized by sol-gel method with tungsten hexachloride (WCl6) as precursor and deposited onto porous silicon and alumina substrates by dip-coating. The morphology and crystal structure of samples were investigated by means of field emission scanning electron microscope and X-ray diffractometer. It is the experimental results demonstrated by gas sensing tests that WO3 nanoparticles combining with the substrate of porous silicon presented an improved NO2-sensing property at room temperature. Compared to WO3 deposited on alumina working above 100 °C, the WO3 nanoparticles/porous silicon exhibited higher properties upon exposure to sub-ppm concentrations of NO2 gas at room temperature. Additionally, the NO2-sensing performance of WO3 nanoparticles/porous silicon was enhanced markedly, in comparison to pure porous silicon. The mechanism of WO3/porous silicon composite structure on the NO2 sensing was explained in detail.

  20. Probing contact-mode characteristics of silicon nanowire electromechanical systems with embedded piezoresistive transducers

    NASA Astrophysics Data System (ADS)

    Yang, Rui; He, Tina; Tupta, Mary Anne; Marcoux, Carine; Andreucci, Philippe; Duraffourg, Laurent; X-L Feng, Philip

    2015-09-01

    This article reports on a new method of monitoring nanoscale contacts in switches based on nanoelectromechanical systems, where the contact-mode switching characteristics can be recorded with the sensitive embedded piezoresistive (PZR) strain transducers. The devices are manufactured using state-of-the-art wafer-scale silicon-on-insulator technology featuring suspended silicon cantilevers and beams as switching elements and sub-100 nm thin silicon nanowires (SiNWs) as PZR transducers. Several different device configurations are studied, including mechanically ‘cross’-shaped (‘+’), coupled cantilever-SiNW structures, with and without local drain electrodes, and doubly clamped SiNW beams. Through detailed measurement and analysis, we demonstrate that the PZR transducers can enable detection of both mechanical and tunneling switching with multiple repeatable cycles. With the strong PZR effects in thin SiNWs, this type of device could be valuable especially for monitoring cold switching events, and when conventional direct readout of the switching events from the local gate or drain electrodes would not be efficient or sensitive, as nanoscale contacts may not be highly conductive, or may be degrading over time.

  1. Assemblies of silicon nanoparticles roll up into flexible nanotubes

    NASA Astrophysics Data System (ADS)

    Chaieb, Sahraoui; Nayfeh, Munir H.; Smith, Adam D.

    2005-08-01

    When a colloidal dispersion of fluorescent 1 nm silicon nanoparticles in alcohol is subjected to an electric field, the nanoparticles are driven to the surface of the anode substrate, where they form a thin film. Upon drying, the film delaminates from the surface of the anode and rolls up into ˜100μm long nanotube. Nanotube diameters ranging from 0.2 to 5μm with wall thicknesses in the range of 20-40 nm have been achieved. By applying a force on the tubes using atomic force microscopy, we estimate Young's modulus of the film and find it to be close to that of rubber. We also study the crystalline structure of the film using electron diffraction and find it to be quartzlike.

  2. Assembly and magnetic properties of nickel nanoparticles on silicon nanowires

    SciTech Connect

    Picraux, Samuel T; Manandhar, Pradeep; Nazaretski, E; Thompson, J

    2009-01-01

    The directed assembly of magnetic Ni nanoparticles at the tips of silicon nanowires is reported. Using electrodeposition Ni shells of thickness from 10 to 100 nm were selectively deposited on Au catalytic seeds at the ends of nanowires. Magnetic characterization confirms a low coercivity ({approx}115 Oe) ferromagnetic behavior at 300 K. This approach to multifunctional magnetic-semiconducting nanostructure assembly could be extended to electrodeposition of other materials on the nanowire ends, opening up novel ways of device integration. Such magnetically functionalized nanowires offer a new approach to developing novel highly localized magnetic probes for high resolution magnetic resonance force microscopy.

  3. Porous silicon nanoparticles as sensitizers for ultrasonic hyperthermia

    SciTech Connect

    Sviridov, A. P. Andreev, V. G.; Ivanova, E. M.; Osminkina, L. A.; Tamarov, K. P.; Timoshenko, V. Yu.

    2013-11-04

    Aqueous suspensions of porous silicon nanoparticles (NPs) with average size ∼100 nm and concentration ∼1 g/L undergo significant heating as compared with pure water under therapeutic ultrasonic (US) irradiation with frequencies of 1–2.5 MHz and intensities of 1–20 W/cm{sup 2}. This effect is explained by taking into account the efficient absorption of US energy by NPs. The observed US-induced heating of biodegradable NPs is promising for applications in ultrasonic hyperthermia of tumors.

  4. Probing magnetic and electric optical responses of silicon nanoparticles

    SciTech Connect

    Permyakov, Dmitry; Sinev, Ivan; Markovich, Dmitry; Samusev, Anton; Belov, Pavel; Ginzburg, Pavel; Valuckas, Vytautas; Kuznetsov, Arseniy I.; Luk'yanchuk, Boris S.; Miroshnichenko, Andrey E.; Neshev, Dragomir N.; Kivshar, Yuri S.

    2015-04-27

    We study experimentally both magnetic and electric optically induced resonances of silicon nanoparticles by combining polarization-resolved dark-field spectroscopy and near-field scanning optical microscopy measurements. We reveal that the scattering spectra exhibit strong sensitivity of electric dipole response to the probing beam polarization and attribute the characteristic asymmetry of measured near-field patterns to the excitation of a magnetic dipole mode. The proposed experimental approach can serve as a powerful tool for the study of photonic nanostructures possessing both electric and magnetic optical responses.

  5. Radially and azimuthally polarized laser induced shape transformation of embedded metallic nanoparticles in glass.

    PubMed

    Tyrk, Mateusz A; Zolotovskaya, Svetlana A; Gillespie, W Allan; Abdolvand, Amin

    2015-09-01

    Radially and azimuthally polarized picosecond (~10 ps) pulsed laser irradiation at 532 nm wavelength led to the permanent reshaping of spherical silver nanoparticles (~30 - 40 nm in diameter) embedded in a thin layer of soda-lime glass. The observed peculiar shape modifications consist of a number of different orientations of nano-ellipsoids in the cross-section of each written line by laser. A Second Harmonic Generation cross-sectional scan method from silver nanoparticles in transmission geometry was adopted for characterization of the samples after laser modification. The presented approach may lead to sophisticated marking of information in metal-glass nanocomposites. PMID:26368440

  6. Spectroellipsometric characterization and modeling of plasmonic diamond-like carbon nanocomposite films with embedded Ag nanoparticles.

    PubMed

    Yaremchuk, Iryna; Meškinis, Šarunas; Fitio, Volodymyr; Bobitski, Yaroslav; Šlapikas, Kestutis; Čiegis, Arvydas; Balevičius, Zigmas; Selskis, Algirdas; Tamulevičius, Sigitas

    2015-01-01

    Diamond-like carbon nanocomposite films with embedded silver nanoparticles are considered experimentally (spectroellipsometric characterization) and theoretically (modeling of optical properties). Metallic nanocomposite films were synthesized by reactive magnetron sputtering and were studied by transmission electron microscope (TEM) and atomic force microscope (AFM). The optical constants of the films were determined from spectroscopic ellipsometry measurements and were modeled using the Maxwell-Garnett approximations. Comparison between the extended and renormalized Maxwell-Garnett theory was conducted. Surface plasmon resonance peak have been found to be strongly dependent on the shape of nanoparticles and interaction between them. PMID:25977645

  7. Liquid-phase plasma synthesis of silicon quantum dots embedded in carbon matrix for lithium battery anodes

    SciTech Connect

    Wei, Ying; Yu, Hang; Li, Haitao; Ming, Hai; Pan, Keming; Huang, Hui; Liu, Yang; Kang, Zhenhui

    2013-10-15

    Graphical abstract: - Highlights: • Silicon quantum dots embedded in carbon matrix (SiQDs/C) were fabricated. • SiQDs/C exhibits excellent battery performance as anode materials with high specific capacity. • The good performance was attributed to the marriage of small sized SiQDs and carbon. - Abstract: Silicon quantum dots embedded in carbon matrix (SiQDs/C) nanocomposites were prepared by a novel liquid-phase plasma assisted synthetic process. The SiQDs/C nanocomposites were demonstrated to show high specific capacity, good cycling life and high coulmbic efficiency as anode materials for lithium-ion battery.

  8. Modification of embedded Cu nanoparticles: Ion irradiation at room temperature

    NASA Astrophysics Data System (ADS)

    Johannessen, B.; Kluth, P.; Giulian, R.; Araujo, L. L.; Llewellyn, D. J.; Foran, G. J.; Cookson, D. J.; Ridgway, M. C.

    2007-04-01

    Cu nanoparticles (NPs) with an average diameter of ∼25 Å were synthesized in SiO2 by ion implantation and thermal annealing. Subsequently, the NPs were exposed to ion irradiation at room temperature simultaneously with a bulk Cu reference film. The ion species/energy was varied to achieve different values for the nuclear energy loss. The short-range atomic structure and average NP diameter were measured by means of extended X-ray absorption fine structure spectroscopy and small angle X-ray scattering, respectively. Transmission electron microscopy yielded complementary results. The short-range order of the Cu films remained unchanged consistent with the high regeneration rate of bulk elemental metals. For the NP samples it was found that increasing nuclear energy loss yielded gradual dissolution of NPs. Furthermore, an increased structural disorder was observed for the residual NPs.

  9. Silver Nanoparticle Enhanced Freestanding Thin-Film Silicon Solar Cells

    NASA Astrophysics Data System (ADS)

    Winans, Joshua David

    As the supply of fossil fuels diminishes in quantity the demand for alternative energy sources will consistently increase. Solar cells are an environmentally friendly and proven technology that suffer in sales due to a large upfront cost. In order to help facilitate the transition from fossil fuels to photovoltaics, module costs must be reduced to prices well below $1/Watt. Thin-film solar cells are more affordable because of the reduced materials costs, but lower in efficiency because less light is absorbed before passing through the cell. Silver nanoparticles placed at the front surface of the solar cell absorb and reradiate the energy of the light in ways such that more of the light ends being captured by the silicon. Silver nanoparticles can do this because they have free electron clouds that can take on the energy of an incident photon through collective action. This bulk action of the electrons is called a plasmon. This work begins by discussing the economics driving the need for reduced material use, and the pros and cons of taking this step. Next, the fundamental theory of light-matter interaction is briefly described followed by an introduction to the study of plasmonics. Following that we discuss a traditional method of silver nanoparticle formation and the initial experimental studies of their effects on the ability of thin-film silicon to absorb light. Then, Finite-Difference Time-Domain simulation software is used to simulate the effects of nanoparticle morphology and size on the scattering of light at the surface of the thin-film.

  10. Current enhancement of aluminum doped ZnO/n-Si isotype heterojunction solar cells by embedding silver nanoparticles.

    PubMed

    Yun, Juhyung; Kim, Joondong; Kojori, Hossein Shokri; Kim, Sung Jim; Tong, Chong; Anderson, Wayne A

    2013-08-01

    To improve Plasmonic energy harvesting, the Al doped ZnO (AZO) and Si heterojunction was studied for plasmonic photovoltaic applications. Silver nanoparticles (Ag NPs) were embedded in AZO, resulting in direct energy absoption from Ag NPs, positioned close to the junction. This structure has a benefit of avoiding highly doped lossy layers of conventional solar cell structures. Al doped ZnO (AZO) was deposited on n-Si substrate by dual beam sputtering method to fabricate AZO/Si heterojunction solar cells. AZO provides a transparent current spreading effect and rectifying junction with n type silicon (Si). Silver nanoparticles (Ag NPs) were embedded in AZO film (240-270 nm thick) with a sandwich-like structure. The position of Ag NPs in the AZO film was controlled to be located at 10, 20 and 40 nm distance from the Si absorber layer. Fabricated solar cells show improved performance in terms of the short circuit current (J(sc)) and the quantum efficiency (QE). Finite difference time domain (FDTD) simulations were carried out to investigate the QE enhancement and optimize photocurrent gain under an AM1.5G solar spectrum. In calculation, absorption enhancement is maximized when Ag NPs are located close to the Si layer in the range of 10-40 nm. Experimentally, 20 nm distance of Ag NPs from the Si showed the best performance with 0.36 V of open circuit voltage (V(oc)), 28.3 mA/cm2 of J(sc) and 5.91% of coversion efficiency. The QE showed 15% of enhancement around lambda = 435 nm and 5-10% of enhancement within lambda = 600-1000 nm. PMID:23882792

  11. Controlled Embedding of Metal Oxide Nanoparticles in ZSM-5 Zeolites through Preencapsulation and Timed Release.

    PubMed

    Lai, Yungchieh; Rutigliano, Michael N; Veser, Götz

    2015-09-29

    We report a straightforward and transferrable synthesis strategy to encapsulate metal oxide nanoparticles (NPs) in mesoporous ZSM-5 via the encapsulation of NPs into silica followed by conversion of the NP@silica precursor to NP@ZSM-5. The systematic bottom-up approach allows for straightforward, precise control of both the metal weight loading and size of the embedded NP and yields uniform NP@ZSM-5 microspheres composed of stacked ZSM-5 nanorods with substantial mesoporosity. Key to the synthesis is the timed release of the embedded NPs during dissolution of the silica matrix in the hydrothermal conversion step, which finely balances the rate of NP release with the rate of SiO2 dissolution and the subsequent nucleation of aluminosilicate. The synthesis approach is demonstrated for Zn, Fe, and Ni oxide encapsulation in ZSM-5 but can be expected to be broadly transferrable for the encapsulation of metal and metal oxide nanoparticles into other zeolite structures. PMID:26352788

  12. Bimetallic ruthenium-copper nanoparticles embedded in mesoporous carbon as an effective hydrogenation catalyst.

    PubMed

    Liu, Jiajia; Zhang, Li Li; Zhang, Jiatao; Liu, Tao; Zhao, X S

    2013-11-21

    Bimetallic ruthenium-copper nanoparticles embedded in the pore walls of mesoporous carbon were prepared via a template route and evaluated in terms of catalytic properties in D-glucose hydrogenation. The existence of bimetallic entities was supported by Ru L3-edge and Cu K-edge X-ray absorption results. The hydrogen spillover effect of the bimetallic catalyst on the hydrogenation reaction was evidenced by the results of both hydrogen and carbon monoxide chemisorptions. The bimetallic catalyst displayed a higher catalytic activity than the single-metal catalysts prepared using the same approach, namely ruthenium or copper nanoparticles embedded in the pore walls of mesoporous carbon. This improvement was due to the changes in the geometric and electronic structures of the bimetallic catalyst because of the presence of the second metal. PMID:24072134

  13. Co3O4 nanoparticle embedded carbonaceous fibres: a nanoconfinement effect on enhanced lithium-ion storage.

    PubMed

    Sun, Jin; Li, Daohao; Xia, Yanzhi; Zhu, Xiaoyi; Zong, Lu; Ji, Quan; Jia, Yi Alec; Yang, Dongjiang

    2015-11-21

    Co3O4 nanoparticle embedded carbonaceous fibres were prepared from Co(2+) coordinated regenerated cellulose fibres, which showed high reversible capacity and excellent cycling stability as anode materials for Li-ion batteries. PMID:26399496

  14. Self-standing, metal nanoparticle embedded transparent films from multi-armed cardanol conjugates through in situ synthesis.

    PubMed

    Jyothish, Kuthanapillil; Vemula, Praveen Kumar; Jadhav, Swapnil R; Francesconi, Lynn C; John, George

    2009-09-28

    We report multi-armed/dendritic molecules having unsaturated side chains for generating scratch-free, self-standing cross-linked transparent films with embedded metal nanoparticles via autoxidation induced in situ synthesis. PMID:19724787

  15. Size effects in the magnetic anisotropy of embedded cobalt nanoparticles: from shape to surface

    PubMed Central

    Oyarzún, Simón; Tamion, Alexandre; Tournus, Florent; Dupuis, Véronique; Hillenkamp, Matthias

    2015-01-01

    Strong size-dependent variations of the magnetic anisotropy of embedded cobalt clusters are evidenced quantitatively by combining magnetic experiments and advanced data treatment. The obtained values are discussed in the frame of two theoretical models that demonstrate the decisive role of the shape in larger nanoparticles and the predominant role of the surface anisotropy in clusters below 3 nm diameter. PMID:26439626

  16. Facile Synthesis of Au Nanoparticles Embedded in an Ultrathin Hollow Graphene Nanoshell with Robust Catalytic Performance.

    PubMed

    Liu, Hongyang; Wang, Jia; Feng, Zhenbao; Lin, Yangming; Zhang, Liyun; Su, Dangsheng

    2015-10-01

    Au nanoparticles (NPs) uniformly embedded into an ultrathin hollow graphene nanoshell (Au@HGN) are synthesized using a facile template-based procedure. The obtained Au@HGN catalyst exhibits robust and stable catalytic performance in the reduction of 4-nitrophenol to 4-aminophenol, compared with that of traditional Au/TiO2 and previously reported Au- and Ag-based catalysts. PMID:26280245

  17. Bimetallic ruthenium-copper nanoparticles embedded in mesoporous carbon as an effective hydrogenation catalyst

    NASA Astrophysics Data System (ADS)

    Liu, Jiajia; Zhang, Li Li; Zhang, Jiatao; Liu, Tao; Zhao, X. S.

    2013-10-01

    Bimetallic ruthenium-copper nanoparticles embedded in the pore walls of mesoporous carbon were prepared via a template route and evaluated in terms of catalytic properties in d-glucose hydrogenation. The existence of bimetallic entities was supported by Ru L3-edge and Cu K-edge X-ray absorption results. The hydrogen spillover effect of the bimetallic catalyst on the hydrogenation reaction was evidenced by the results of both hydrogen and carbon monoxide chemisorptions. The bimetallic catalyst displayed a higher catalytic activity than the single-metal catalysts prepared using the same approach, namely ruthenium or copper nanoparticles embedded in the pore walls of mesoporous carbon. This improvement was due to the changes in the geometric and electronic structures of the bimetallic catalyst because of the presence of the second metal.Bimetallic ruthenium-copper nanoparticles embedded in the pore walls of mesoporous carbon were prepared via a template route and evaluated in terms of catalytic properties in d-glucose hydrogenation. The existence of bimetallic entities was supported by Ru L3-edge and Cu K-edge X-ray absorption results. The hydrogen spillover effect of the bimetallic catalyst on the hydrogenation reaction was evidenced by the results of both hydrogen and carbon monoxide chemisorptions. The bimetallic catalyst displayed a higher catalytic activity than the single-metal catalysts prepared using the same approach, namely ruthenium or copper nanoparticles embedded in the pore walls of mesoporous carbon. This improvement was due to the changes in the geometric and electronic structures of the bimetallic catalyst because of the presence of the second metal. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03813k

  18. Fluorescent cadmium telluride quantum dots embedded chitosan nanoparticles: a stable, biocompatible preparation for bio-imaging.

    PubMed

    Ghormade, Vandana; Gholap, Haribhau; Kale, Sonia; Kulkarni, Vaishnavi; Bhat, Suresh; Paknikar, Kishore

    2015-01-01

    Fluorescent cadmium telluride quantum dots (CdTe QDs) are an optically attractive option for bioimaging, but are known to display high cytotoxicity. Nanoparticles synthesized from chitosan, a natural biopolymer of β 1-4 linked glucosamine, display good biocompatibility and cellular uptake. A facile, green synthetic strategy has been developed to embed green fluorescent cadmium telluride quantum dots (CdTe QDs) in biocompatible CNPs to obtain a safer preparation than 'as is' QDs. High-resolution transmission electron microscopy showed the crystal lattice corresponding to CdTe QDs embedded in CNPs while thermogravimetry confirmed their polymeric composition. Electrostatic interactions between thiol-capped QDs (4 nm, -57 mV) and CNPs (~300 nm, +38 mV) generated CdTe QDs-embedded CNPs that were stable up to three months. Further, viability of NIH3T3 mouse fibroblast cells in vitro increased in presence of QDs-embedded CNPs as compared to bare QDs. At the highest concentration (10 μg/ml), the former shows 34 and 39% increase in viability at 24 and 48 h, respectively, as compared to the latter. This shows that chitosan nanoparticles do not release the QDs up to 48 h and do not cause extended toxicity. Furthermore, hydrolytic enzymes such as lysozyme and chitinase did not degrade chitosan nanoparticles. Moreover, QDs-embedded CNPs show enhanced internalization in NIH3T3 cells as compared to bare QDs. This method offers ease of synthesis and handling of stable, luminescent, biocompatible CdTe QDs-embedded CNPs with a favorable toxicity profile and better cellular uptake with potential for bioimaging and targeted detection of cellular components. PMID:25410797

  19. Large reduction in thermal conductivity for SiGe alloy nanowire wrapped with a Ge nanoparticle-embedded SiO2 shell.

    PubMed

    Lee, Jong Woon; Lee, Junho; Jung, Su-Ho; Jang, Yamujin; Choi, Byoung Lyong; Yang, Cheol-Woong; Whang, Dongmok; Lee, Eun Kyung

    2016-07-29

    We demonstrate silicon germanium (SiGe) alloy nanowires (NWs) with Ge nanoparticles (GeNPs) embedded in a SiO2 shell as a material for decreasing thermal conductivity. During thermal oxidation of SiGe NWs to form SiGe-SiO2 core-shell structures, Ge atoms were diffused into the SiO2 shell to relax the strain in the SiGe core, and agglomerated as a few nanometer-sized particles. This structure leads to a large reduction in thermal conductivity due to the GeNP-phonon interaction, while electrical conductivity is sustained because the core of the SiGe alloy NW provides a current path for the charged carriers. The thermal conductivity of the SiGe alloy NWs wrapped with a GeNP-embedded SiO2 shell is 0.41 W m(-1) K(-1) at 300 K. PMID:27306569

  20. Large reduction in thermal conductivity for SiGe alloy nanowire wrapped with a Ge nanoparticle-embedded SiO2 shell

    NASA Astrophysics Data System (ADS)

    Lee, Jong Woon; Lee, Junho; Jung, Su-Ho; Jang, Yamujin; Choi, Byoung Lyong; Yang, Cheol-Woong; Whang, Dongmok; Lee, Eun Kyung

    2016-07-01

    We demonstrate silicon germanium (SiGe) alloy nanowires (NWs) with Ge nanoparticles (GeNPs) embedded in a SiO2 shell as a material for decreasing thermal conductivity. During thermal oxidation of SiGe NWs to form SiGe–SiO2 core–shell structures, Ge atoms were diffused into the SiO2 shell to relax the strain in the SiGe core, and agglomerated as a few nanometer-sized particles. This structure leads to a large reduction in thermal conductivity due to the GeNP–phonon interaction, while electrical conductivity is sustained because the core of the SiGe alloy NW provides a current path for the charged carriers. The thermal conductivity of the SiGe alloy NWs wrapped with a GeNP-embedded SiO2 shell is 0.41 W m‑1 K‑1 at 300 K.

  1. Magnetic properties of Ni nanoparticles embedded in silica matrix (KIT-6) synthesized via novel chemical route

    SciTech Connect

    Dalavi, Shankar B.; Panda, Rabi N.; Raja, M. Manivel

    2015-06-24

    Thermally stable Ni nanoparticles have been embedded in mesoporous silica matrix (KIT-6) via novel chemical reduction method by using superhydride as reducing agent. X-ray diffraction (XRD) study confirms that pure and embedded Ni nanoparticles crystallize in face centered cubic (fcc) structure. Crystallite sizes of pure Ni, 4 wt% and 8 wt% Ni in silica were estimated to be 6.0 nm, 10.4 nm and 10.5 nm, respectively. Morphology and dispersion of Ni in silica matrix were studied by scanning electron microscopy (SEM). Magnetic study shows enhancement of magnetic moments of Ni nanoparticles embedded in silica matrix compared with that of pure Ni. The result has been interpreted on the basis of size reduction and magnetic exchange effects. Saturation magnetization values for pure Ni, 4 wt% and 8 wt% Ni in silica were found to be 15.77 emu/g, 5.08 emu/g and 2.00 emu/g whereas coercivity values were 33.72 Oe, 92.47 Oe and 64.70 Oe, respectively. We anticipate that the observed magnetic properties may find application as soft magnetic materials.

  2. Enhanced antioxidant activity of gold nanoparticle embedded 3,6-dihydroxyflavone: a combinational study

    NASA Astrophysics Data System (ADS)

    Medhe, Sharad; Bansal, Prachi; Srivastava, Man Mohan

    2012-12-01

    The antioxidative effect of selected dietary compounds (3,6-dihydroxyflavone, lutein and selenium methyl selenocysteine) was determined in single and combination using DPPH (2,2-diphenyl-l-picrylhydrazyl), OH (hydroxyl), H2O2 (hydrogen peroxide) and NO (nitric oxide) radical scavenging assays. Radical scavenging effect of the dietary phytochemicals individually are found to be in the order: ascorbic acid (standard) > lutein > 3,6-dihydroxyflavone > selenium methyl selenocysteine, at concentration 100 μg/ml, confirmed by all the four bioassays (p < 0.05). Among the various combinations studied, the triplet combination of 3,6-dihydroxyflavone, lutein and selenium methyl selenocysteine (1:1:1), exhibited enhancement in the target activity at same concentration level. Synthesized gold nanoparticle embedded 3,6-dihydroxyflavone further enhanced the target antioxidant activity. The combinational study including gold nanoparticle embedded 3,6-dihydroxyflavone with other native dietary nutrients showed remarkable increase in antioxidant activity at the same concentration level. The present in vitro study on combinational and nanotech enforcement of dietary phytochemicals shows the utility in the architecture of nanoparticle embedded phytoproducts having a wide range of applications in medical science.

  3. Formation of DNA-network embedding ferromagnetic Cobalt nano-particles

    NASA Astrophysics Data System (ADS)

    Kanki, Teruo; Tanaka, Hidekazu; Shirakawa, Hideaki; Sacho, Yu; Taniguchi, Masateru; Lee, Hea-Yeon; Kawai, Tomoji; Kang, Nam-Jung; Chen, Jinwoo

    2002-03-01

    Formation of DNA-network embedding ferromagnetic Cobalt nano-particles T. Kanki, Hidekazu. Tanaka, H. Shirakawa, Y. Sacho, M. Taniguchi, H. Lee, T. Kawai The Institute of Scientific and Industrial Research, Osaka University, Japan and Nam-Jung Kang, Jinwoo Chen Korea Advanced Institute of Science and Technology (KAIST), Korea DNA can be regarded as a naturally occurring and highly specific functional biopolymer and as a fine nano-wire. Moreover, it was found that large-scale DNA networks can be fabricated on mica surfaces. By using this network structure, we can expect to construct nano-scale assembly of functional nano particle, for example ferromagnetic Co nano particles, toward nano scale spin-electronics based on DNA circuits. When we formed DNA network by 250mg/ml DNA solution of poly(dG)-poly(dC) including ferromagnetic Co nano particles (diameter of 12nm), we have conformed the DNA network structure embedding Co nano-particles (height of about 12nm) by atomic force microscopy. On the other hand, we used 100mg/ml DNA solution, DNA can not connect each other, and many Co nano-particles exist without being embedded.

  4. Silver nanoparticle-embedded polymersome nanocarriers for the treatment of antibiotic-resistant infections

    NASA Astrophysics Data System (ADS)

    Geilich, Benjamin M.; van de Ven, Anne L.; Singleton, Gloria L.; Sepúlveda, Liuda J.; Sridhar, Srinivas; Webster, Thomas J.

    2015-02-01

    The rapidly diminishing number of effective antibiotics that can be used to treat infectious diseases and associated complications in a physician's arsenal is having a drastic impact on human health today. This study explored the development and optimization of a polymersome nanocarrier formed from a biodegradable diblock copolymer to overcome bacterial antibiotic resistance. Here, polymersomes were synthesized containing silver nanoparticles embedded in the hydrophobic compartment, and ampicillin in the hydrophilic compartment. Results showed for the first time that these silver nanoparticle-embedded polymersomes (AgPs) inhibited the growth of Escherichia coli transformed with a gene for ampicillin resistance (bla) in a dose-dependent fashion. Free ampicillin, AgPs without ampicillin, and ampicillin polymersomes without silver nanoparticles had no effect on bacterial growth. The relationship between the silver nanoparticles and ampicillin was determined to be synergistic and produced complete growth inhibition at a silver-to-ampicillin ratio of 1 : 0.64. In this manner, this study introduces a novel nanomaterial that can effectively treat problematic, antibiotic-resistant infections in an improved capacity which should be further examined for a wide range of medical applications.

  5. Transport properties of β-Ga2O3 nanoparticles embedded in Nb thin films

    NASA Astrophysics Data System (ADS)

    Vaidhyanathan, L. S.; Srinivasan, M. P.; Chandra Mohan, P.; Baisnab, D. K.; Mythili, R.; Janawadkar, M. P.

    2015-01-01

    The origin of ferromagnetism in nanoparticles of nonmagnetic oxides is an interesting area of research. In the present work, transport properties of niobium thin films, with β-Ga2O3 nanoparticles embedded within them, are presented. Nanoparticles of β-Ga2O3 embedded in a Nb matrix were prepared at room temperature by radio frequency co-sputtering technique on Si (100) and glass substrates held at room temperature. The thin films deposited on Si substrates were subjected to Ar annealing at a temperature range of 600-650 C for 1 hour. Films were characterized by X-ray diffraction (XRD), Micro-Raman and elemental identification was performed with an Energy Dispersive X-ray Spectroscopy (EDS). Transport measurements were performed down to liquid helium temperatures by four-probe contact technique, showed characteristics analogous to those observed in the context of a Kondo system. A comparison of the experimental data with the theoretical formalism of Kondo and Hamann is presented. It is suggested that this behavior arises from the existence of magnetic moments associated with the oxygen vacancy defects in the nanoparticles of the nonmagnetic oxide Ga2O3.

  6. MIL-100 derived nitrogen-embodied carbon shells embedded with iron nanoparticles

    NASA Astrophysics Data System (ADS)

    Mao, Chengyu; Kong, Aiguo; Wang, Yuan; Bu, Xianhui; Feng, Pingyun

    2015-06-01

    The use of metal-organic frameworks (MOFs) as templates and precursors to synthesize new carbon materials with controllable morphology and pre-selected heteroatom doping holds promise for applications as efficient non-precious metal catalysts. Here, we report a facile pyrolysis pathway to convert MIL-100 into nitrogen-doped carbon shells encapsulating Fe nanoparticles in a comparative study involving multiple selected nitrogen sources. The hierarchical porous architecture, embedded Fe nanoparticles, and nitrogen decoration endow this composite with a superior oxygen reduction activity. Furthermore, the excellent durability and high methanol tolerance even outperform the commercial Pt-C catalyst.The use of metal-organic frameworks (MOFs) as templates and precursors to synthesize new carbon materials with controllable morphology and pre-selected heteroatom doping holds promise for applications as efficient non-precious metal catalysts. Here, we report a facile pyrolysis pathway to convert MIL-100 into nitrogen-doped carbon shells encapsulating Fe nanoparticles in a comparative study involving multiple selected nitrogen sources. The hierarchical porous architecture, embedded Fe nanoparticles, and nitrogen decoration endow this composite with a superior oxygen reduction activity. Furthermore, the excellent durability and high methanol tolerance even outperform the commercial Pt-C catalyst. Electronic supplementary information (ESI) available: Material synthesis and elemental analysis, electrochemistry measurements, and additional figures. See DOI: 10.1039/c5nr02346g

  7. Silver nanoparticle-embedded polymersome nanocarriers for the treatment of antibiotic-resistant infections.

    PubMed

    Geilich, Benjamin M; van de Ven, Anne L; Singleton, Gloria L; Sepúlveda, Liuda J; Sridhar, Srinivas; Webster, Thomas J

    2015-02-28

    The rapidly diminishing number of effective antibiotics that can be used to treat infectious diseases and associated complications in a physician's arsenal is having a drastic impact on human health today. This study explored the development and optimization of a polymersome nanocarrier formed from a biodegradable diblock copolymer to overcome bacterial antibiotic resistance. Here, polymersomes were synthesized containing silver nanoparticles embedded in the hydrophobic compartment, and ampicillin in the hydrophilic compartment. Results showed for the first time that these silver nanoparticle-embedded polymersomes (AgPs) inhibited the growth of Escherichia coli transformed with a gene for ampicillin resistance (bla) in a dose-dependent fashion. Free ampicillin, AgPs without ampicillin, and ampicillin polymersomes without silver nanoparticles had no effect on bacterial growth. The relationship between the silver nanoparticles and ampicillin was determined to be synergistic and produced complete growth inhibition at a silver-to-ampicillin ratio of 1 : 0.64. In this manner, this study introduces a novel nanomaterial that can effectively treat problematic, antibiotic-resistant infections in an improved capacity which should be further examined for a wide range of medical applications. PMID:25628231

  8. Embedded Ceria Nanoparticles in Crosslinked PVA Electrospun Nanofibers as Optical Sensors for Radicals.

    PubMed

    Shehata, Nader; Samir, Effat; Gaballah, Soha; Hamed, Aya; Elrasheedy, Asmaa

    2016-01-01

    This work presents a new nanocomposite of cerium oxide (ceria) nanoparticles embedded in electrospun PVA nanofibers for optical sensing of radicals in solutions. Our ceria nanoparticles are synthesized to have O-vacancies which are the receptors for the radicals extracted from peroxide in water solution. Ceria nanoparticles are embedded insitu in PVA solution and then formed as nanofibers using an electrospinning technique. The formed nanocomposite emits visible fluorescent emissions under 430 nm excitation, due to the active ceria nanoparticles with fluorescent Ce(3+) ionization states. When the formed nanocomposite is in contact with peroxide solution, the fluorescence emission intensity peak has been found to be reduced with increasing concentration of peroxide or the corresponding radicals through a fluorescence quenching mechanism. The fluorescence intensity peak is found to be reduced to more than 30% of its original value at a peroxide weight concentration up to 27%. This work could be helpful in further applications of radicals sensing using a solid mat through biomedical and environmental monitoring applications. PMID:27571083

  9. Design and Testing of Metal and Silicon Heat Spreaders with Embedded Micromachined Heat Pipes

    SciTech Connect

    Benson, D.A.; Robino, C.V.

    1999-02-22

    The authors have developed a new type of heat spreader based on the integration of heat pipes directly within a thin planar structure suitable for use as a heat spreader or as the base layer in a substrate. The process uses micromachining methods to produce micron scale patterns that act as a wick in these small scale heat pipes. By using silicon or a low expansion metal as the wall material of these spreaders, they achieve a good match to the thermal coefficient of expansion of the die. The match allows the use of a thin high performance die attachment even on large size die. The embedded heat pipes result in high effective thermal conductivity for the new spreader technology.

  10. Preparation and Evaluation of Contact Lenses Embedded with Polycaprolactone-Based Nanoparticles for Ocular Drug Delivery.

    PubMed

    Nasr, Farzaneh Hashemi; Khoee, Sepideh; Dehghan, Mohammad Mehdi; Chaleshtori, Sirous Sadeghian; Shafiee, Abbas

    2016-02-01

    To improve the efficiency of topical ocular drug administration, we focused on development of a nanoparticles loaded contact lens to deliver the hydrophobic drug over a prolonged period of time. The cross-linked nanoparticles based on PCL (poly ε-caprolactone), 2-hydroxy ethyl methacrylate (HEMA), and poly ethylene glycol diacrylate (PEG-DA) were prepared by surfactant-free miniemulsion polymerization. The lens material was prepared through photopolymerization of HEMA and N-vinylpyrrolidone (NVP) using PEG-DA as the cross-linker. Effects of nanoparticles loading on critical contact lens properties such as transparency, water content, modulus and ion and oxygen permeabilities were studied. Nanoparticles and hydrogel showed high viability, indicating the absence of cytotoxicity and stimulatory effect. Drug release studies revealed that the hydrogel embedded with nanoparticles released the drug for a period of 12 days. The results of this study provide evidence that nanoparticles loaded hydrogels could be used for extended delivery of loteprednol etabonate and perhaps other drugs. PMID:26652301

  11. Ion-irradiation-induced amorphization of Cu nanoparticles embedded in SiO2

    NASA Astrophysics Data System (ADS)

    Johannessen, B.; Kluth, P.; Llewellyn, D. J.; Foran, G. J.; Cookson, D. J.; Ridgway, M. C.

    2007-11-01

    Elemental Cu nanoparticles embedded in SiO2 were irradiated with 5MeVSn3+ . The nanoparticle structure was studied as a function of Sn3+ fluence by extended x-ray absorption fine structure spectroscopy, small-angle x-ray scattering, and transmission electron microscopy. Prior to irradiation, Cu nanoparticles exhibited the face-centered-cubic structure. Upon irradiation at intermediate fluences ( 1×1013 to 1×1014ions/cm2 ), the first nearest neighbor Cu-Cu coordination number decreased, while the Debye-Waller factor, bondlength, and third cumulant of the bondlength distribution increased. In particular, at a fluence of 1×1014ions/cm2 we argue for the presence of an amorphous Cu phase, for which we deduce the structural parameters. Low temperature annealing (insufficient for nanoparticle growth) of the amorphous Cu returned the nanoparticles to the initial preirradiation structure. At significantly higher irradiation fluences ( 1×1015 to 1×1016ions/cm2 ), the nanoparticles were dissolved in the matrix with a Cu coordination similar to that of Cu2O .

  12. Photoluminescence study of PVP capped CdS nanoparticles embedded in PVA matrix

    SciTech Connect

    Pattabi, Manjunatha . E-mail: manjupattabi@yahoo.com; Saraswathi Amma, B.; Manzoor, K.

    2007-05-03

    Photoluminescence properties of polyvinyl pyrrolidone (PVP) capped cadmium sulphide (CdS) nanoparticles embedded in polyvinyl alcohol matrix (PVA) are reported. The PVP-CdS nanoparticles are prepared by non-aqueous method wherein cadmium nitrate is used as the cadmium source and hydrogen sulphide as the sulphur source. The synthesized nanoparticles are dispersed in polyvinyl alcohol (PVA) matrix and cast as self-standing flexible (PVP-CdS)-PVA films. The nanocomposites are characterized by optical absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. XRD and TEM studies show the formation of cubic CdS particles with average size {approx}3-5 nm. Thermal studies, carried out to observe the changes in PVA matrix due to the incorporation of PVP-CdS nanoparticles show strong interaction between the polymer matrix and nanoparticles. The photoluminescence emission spectra of the nanocomposites show two peaks, at 502 and 636 nm, which are attributed to the band edge and surface defects respectively, of CdS nanoparticles. Effective surface capping with optimum concentration of polyvinyl pyrrolidone leads to the quenching of surface defect-related emission.

  13. Effect of large mechanical stress on the magnetic properties of embedded Fe nanoparticles.

    PubMed

    Saranu, Srinivasa; Selve, Sören; Kaiser, Ute; Han, Luyang; Wiedwald, Ulf; Ziemann, Paul; Herr, Ulrich

    2011-01-01

    Magnetic nanoparticles are promising candidates for next generation high density magnetic data storage devices. Data storage requires precise control of the magnetic properties of materials, in which the magnetic anisotropy plays a dominant role. Since the total magneto-crystalline anisotropy energy scales with the particle volume, the storage density in media composed of individual nanoparticles is limited by the onset of superparamagnetism. One solution to overcome this limitation is the use of materials with extremely large magneto-crystalline anisotropy. In this article, we follow an alternative approach by using magneto-elastic interactions to tailor the total effective magnetic anisotropy of the nanoparticles. By applying large biaxial stress to nanoparticles embedded in a non-magnetic film, it is demonstrated that a significant modification of the magnetic properties can be achieved. The stress is applied to the nanoparticles through expansion of the substrate during hydrogen loading. Experimental evidence for stress induced magnetic effects is presented based on temperature-dependent magnetization curves of superparamagnetic Fe particles. The results show the potential of the approach for adjusting the magnetic properties of nanoparticles, which is essential for application in future data storage media. PMID:21977439

  14. Pt nanoparticles embedded on reduced graphite oxide with excellent electrocatalytic properties

    NASA Astrophysics Data System (ADS)

    Saravanan, Gengan; Mohan, Subramanian

    2016-11-01

    Economically viable electrochemical approach has been developed for the synthesis of Pt nanoparticles through electrodeposition technique on the surface of Reduced Graphite Oxide (RGO). Pt nanoparticles embedded Reduced Graphite Oxide on Glassy Carbon Electrode are employed (Pt-rGO/GCE) for electrooxidation of formic acid. Scanning Electron Microscopy (SEM) image and Transmission Electron Microscopy (TEM) image shows that reduced graphite oxide act as an excellent support to anchor the Pt nanoparticles. Cyclic voltammetry results confirmed that Pt-rGO/GCE enhanced current density as many folds than that of bare platinum electrode for electrooxidation of formic acid. X-ray diffraction (XRD) patterns for Pt-graphene composites illustrate that peaks at 69.15 and 23° for Pt (220) and graphene carbon (002) respectively. 13C NMR spectrum of the electrochemically reduced graphite oxide resonance contains only one peak at 133 ppm which retains graphitic sp2 carbon and does not contain any oxygenated carbon and the carbonyl carbons.

  15. Femtosecond laser deposition of TiO2 nanoparticle-assembled films with embedded CdS nanoparticles

    NASA Astrophysics Data System (ADS)

    Ni, Xiao-chang; Sang, Li-xia; Zhang, Hong-jie; Kiliyanamkandy, Anoop; Amoruso, Salvatore; Wang, Xuan; Fittipaldi, Rosalba; Li, Tong; Hu, Ming-lie; Xu, Li-juan

    2014-01-01

    Based on the normal pulsed laser ablation method, femtosecond pulsed laser deposition (fs-PLD) is adopted in vacuum for the production of TiO2 nanoparticle-assembled films. We study the morphology and electronic characteristics of TiO2 nanoparticle-assembled films deposited at different oxygen background gas pressures from high vacuum (˜10-4 Pa) to 100 Pa and different deposition time. Our results show that TiO2 nanoparticle-assembled films obtained in high vacuum present both a mixture with rutile phase and anatase phase and a pure rutile phase. At the same time, there are more mesoporous structures in the film after annealing, which is beneficial for the enhancement of photocatalytic activity. In water splitting experiment, part of the TiO2 nanoparticle-assembled films embedded with a small mass fraction of CdS nanoparticles (˜5%) present an interesting photocurrent enhancement with a maximum value of ˜0.2 mA/cm2 under a solar simulator.

  16. Photophysical properties of blue – emitting silicon nanoparticles

    PubMed Central

    Portolés, Manuel J. Llansola; Nieto, Felipe Rodriguez; Soria, Delia B.; Amalvy, Javier I.; Peruzzo, Pablo J.; Mártire, Daniel O.; Kotler, Mónica; Holub, Oliver; Gonzalez, Mónica C.

    2012-01-01

    Silicon nanoparticles with strong blue photoluminescence were synthesized by electrochemical etching of silicon wafers and ultrasonically removed under N2 atmosphere in organic solvents to produce colloids. Thermal treatment leads to the formation of colloidal Si particles of 3 ± 1 nm diameter, which upon excitation with 340 – 380 nm light exhibited room temperature luminescence in the range from 400 to 500 nm. The emission and the one- and two-photon excitation spectra of the particles are not sensitive to surface functionalization with methyl 2-methylprop-2-enoate. However, the derivatized particles show higher emission quantum yields in air-saturated suspensions (44%) than the underivatized particles (27%), as well as higher stability of its dispersions. FTIR and XPS spectra indicate a significant surface oxidation of the particles. The Si:O:C ratio at the surface of the derivatized particles estimated from XPS is Si3O6(C5O2Hy)1, with y = 7 - 8. Vibronic spacing is observed in both the emission and excitation spectra. The information obtained from one-photon excitation experiments (emission and excitation spectra, photoluminescence quantum yields, luminescence decay lifetimes and anisotropy correlation lifetimes), as well as from two-photon excitation fluorescence correlation spectroscopy (brightness and diffusion coefficients) and TEM indicate that the blue-emitting particles are monodisperse and ball-shaped. Particle size clearly determines the emission and excitation spectral region, as expected from quantum confinement, but the presence and extent of Si-O species on the silicon networks seem crucial for determining the spectrum features and intensity of emission. The nanoparticles could hold great potential as quantum dots for applications as luminescence sensors in biology and environmental science. PMID:22866180

  17. Rheology and stability kinetics of bare silicon nanoparticle inks for low-cost direct printing

    SciTech Connect

    More, Priyesh V.; Jeong, Sunho; Seo, Yeong-Hui; Ryu, Beyong-Hwan; Choi, Youngmin; Kim, Seong Jip; Nahm, Sahn

    2013-12-16

    Highly dispersed and stable silicon nanoparticles ink is formulated for its application in direct printing or printable electronics. These dispersions are prepared from free-standing silicon nanoparticles which are not capped with any organic ligand, making it suitable for electronic applications. Silicon nanoparticles dispersions are prepared by suspending the nanoparticles in benzonitrile or ethanol by using polypropylene glycol (PPG) as a binder. All the samples show typical shear thinning behavior while the dispersion samples show low viscosities signifying good quality dispersion. Such thinning behavior favors in fabrication of dense films with spin-coating or patterns with drop casting. The dispersion stability is monitored by turbiscan measurements showing good stability for one week. A low-cost direct printing method for dispersion samples is also demonstrated to obtain micro-sized patterns. Low electrical resistivity of resulting patterns, adjustable viscosity and good stability makes these silicon nanoparticles dispersions highly applicable for direct printing process.

  18. Rheology and stability kinetics of bare silicon nanoparticle inks for low-cost direct printing

    NASA Astrophysics Data System (ADS)

    More, Priyesh V.; Jeong, Sunho; Seo, Yeong-Hui; Kim, Seong Jip; Nahm, Sahn; Ryu, Beyong-Hwan; Choi, Youngmin

    2013-12-01

    Highly dispersed and stable silicon nanoparticles ink is formulated for its application in direct printing or printable electronics. These dispersions are prepared from free-standing silicon nanoparticles which are not capped with any organic ligand, making it suitable for electronic applications. Silicon nanoparticles dispersions are prepared by suspending the nanoparticles in benzonitrile or ethanol by using polypropylene glycol (PPG) as a binder. All the samples show typical shear thinning behavior while the dispersion samples show low viscosities signifying good quality dispersion. Such thinning behavior favors in fabrication of dense films with spin-coating or patterns with drop casting. The dispersion stability is monitored by turbiscan measurements showing good stability for one week. A low-cost direct printing method for dispersion samples is also demonstrated to obtain micro-sized patterns. Low electrical resistivity of resulting patterns, adjustable viscosity and good stability makes these silicon nanoparticles dispersions highly applicable for direct printing process.

  19. Silicon nanoparticle-functionalized fiberglass pads for sampling

    SciTech Connect

    Mantey, Kevin; Nayfeh, Munir H.; Al-Hreish, Bahjat; Boparai, Jack; Kumar, Ashok; Stephenson, Larry D.; Nelson, Andrew J.; Alrokayan, Salman A.; Abu-Salah, Khalid M.

    2011-03-15

    We used wet treatment to immobilize luminescent silicon nanoparticles on industrial glass fibers to impart optical and chemical functions to the fiber. Carpets or pads consisting of thousands of fibers are processed in parallel, enhancing the sensitivity of detection and the sampled volume. Treated pads exhibit strong luminescence, characteristic of the luminescence of the particles; showing no shift, broadening, or reduction of quantum efficiency. We demonstrate that drawing material by the pad due to physical adsorption can be reversed. We also demonstrate that allylamine can be covalently attached by photoinduced irradiation reactions, which results in imprinting the amine emission spectrum, providing spectral recognition. The imprint accompanied with a blue-shifting of the luminescence spectrum of the probe, allowing examination of the effect of termination on the nanoparticle structure. The shift is found to be consistent with an increase in the bandgap of the Si nanoparticle and is consistent with Quantum Monte Carlo calculations. In addition to sampling, the nano probe pad has the potential to enable a variety of biomedical applications through subsequent attachment.

  20. Raman Spectroscopic Study on Phosphorous-Doped Silicon Nanoparticles.

    PubMed

    Momose, Miho; Hirasaka, Masao; Furukawa, Yukio

    2015-07-01

    The Raman spectra of films prepared from 8, 19, and 30 nm nanoparticles of silicon doped with phosphorous were measured with excitation at 514.5 nm. The observed spectra were analyzed by decomposing the observed Raman bands into three symmetric Voigt function bands, which were assigned to the Si-Si stretching modes of crystalline, boundary, and amorphous-like components. The fractions of crystalline, boundary, and amorphous-like regions were estimated from the obtained components. The obtained fractions can be explained as a sphere-like nanoparticle consisting of a crystalline core surrounded with boundary and amorphous-like shells, which is consistent with the transmission electron microscope images showing a sphere-like shape. The observed spectral shape of the 8 nm nanoparticle film showed significant changes upon light irradiation with a power density of 5.5 kW cm(-2), i.e., the amorphous-like region converted to a crystalline one. The temperature of the film under laser irradiation was estimated to be lower than 1041 °C from the anti-Stokes to the Stokes Raman bands due to the Si-Si stretching mode. The observed partial crystallization is probably induced by heating associated with light irradiation. PMID:26036307

  1. Plasmonic Au nanoparticles embedding enhances the activity and stability of CdS for photocatalytic hydrogen evolution.

    PubMed

    Yu, Guiyang; Wang, Xiang; Cao, Jungang; Wu, Shujie; Yan, Wenfu; Liu, Gang

    2016-02-01

    The activity and stability of CdS for visible-light-driven hydrogen evolution could be significantly enhanced by embedding plasmonic Au nanoparticles. The plasmon resonance energy field of Au nanoparticles could increase the formation rate and lifetime of e(-)/h(+) pairs in CdS semiconductors. PMID:26732587

  2. Electronic properties of embedded graphene: doped amorphous silicon/CVD graphene heterostructures.

    PubMed

    Arezki, Hakim; Boutchich, Mohamed; Alamarguy, David; Madouri, Ali; Alvarez, José; Cabarrocas, Pere Roca I; Kleider, Jean-Paul; Yao, Fei; Hee Lee, Young

    2016-10-12

    Large-area graphene film is of great interest for a wide spectrum of electronic applications, such as field effect devices, displays, and solar cells, among many others. Here, we fabricated heterostructures composed of graphene (Gr) grown by chemical vapor deposition (CVD) on copper substrate and transferred to SiO2/Si substrates, capped by n‑ or p-type doped amorphous silicon (a-Si:H) deposited by plasma-enhanced chemical vapor deposition. Using Raman scattering we show that despite the mechanical strain induced by the a-Si:H deposition, the structural integrity of the graphene is preserved. Moreover, Hall effect measurements directly on the embedded graphene show that the electronic properties of CVD graphene can be modulated according to the doping type of the a-Si:H as well as its phase i.e. amorphous or nanocrystalline. The sheet resistance varies from 360 Ω sq(-1) to 1260 Ω sq(-1) for the (p)-a-Si:H/Gr (n)-a-Si:H/Gr, respectively. We observed a temperature independent hole mobility of up to 1400 cm(2) V(-1) s(-1) indicating that charge impurity is the principal mechanism limiting the transport in this heterostructure. We have demonstrated that embedding CVD graphene under a-Si:H is a viable route for large scale graphene based solar cells or display applications. PMID:27506254

  3. Exchange bias of Ni nanoparticles embedded in an antiferromagnetic IrMn matrix.

    PubMed

    Kuerbanjiang, Balati; Wiedwald, Ulf; Haering, Felix; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul; Herr, Ulrich

    2013-11-15

    The magnetic properties of Ni nanoparticles (Ni-NPs) embedded in an antiferromagnetic IrMn matrix were investigated. The Ni-NPs of 8.4 nm mean diameter were synthesized by inert gas aggregation. In a second processing step, the Ni-NPs were in situ embedded in IrMn films or SiOx films under ultrahigh vacuum (UHV) conditions. Findings showed that Ni-NPs embedded in IrMn have an exchange bias field HEB = 821 Oe at 10 K, and 50 Oe at 300 K. The extracted value of the exchange energy density is 0.06 mJ m(-2) at 10 K, which is in good accordance with the results from multilayered thin film systems. The Ni-NPs embedded in SiOx did not show exchange bias. As expected for this particle size, they are superparamagnetic at T = 300 K. A direct comparison of the Ni-NPs embedded in IrMn or SiOx reveals an increase of the blocking temperature from 210 K to around 400 K. The coercivity of the Ni-NPs exchange coupled to the IrMn matrix at 10 K is 8 times larger than the value for Ni-NPs embedded in SiOx. We studied time-dependent remanent magnetization at different temperatures. The relaxation behavior is described by a magnetic viscosity model which reflects a rather flat distribution of energy barriers. Furthermore, we investigated the effects of different field cooling processes on the magnetic properties of the embedded Ni-NPs. Exchange bias values fit to model calculations which correlate the contribution of the antiferromagnetic IrMn matrix to its grain size. PMID:24141385

  4. Exchange bias of Ni nanoparticles embedded in an antiferromagnetic IrMn matrix

    NASA Astrophysics Data System (ADS)

    Kuerbanjiang, Balati; Wiedwald, Ulf; Haering, Felix; Biskupek, Johannes; Kaiser, Ute; Ziemann, Paul; Herr, Ulrich

    2013-11-01

    The magnetic properties of Ni nanoparticles (Ni-NPs) embedded in an antiferromagnetic IrMn matrix were investigated. The Ni-NPs of 8.4 nm mean diameter were synthesized by inert gas aggregation. In a second processing step, the Ni-NPs were in situ embedded in IrMn films or SiOx films under ultrahigh vacuum (UHV) conditions. Findings showed that Ni-NPs embedded in IrMn have an exchange bias field HEB = 821 Oe at 10 K, and 50 Oe at 300 K. The extracted value of the exchange energy density is 0.06 mJ m-2 at 10 K, which is in good accordance with the results from multilayered thin film systems. The Ni-NPs embedded in SiOx did not show exchange bias. As expected for this particle size, they are superparamagnetic at T = 300 K. A direct comparison of the Ni-NPs embedded in IrMn or SiOx reveals an increase of the blocking temperature from 210 K to around 400 K. The coercivity of the Ni-NPs exchange coupled to the IrMn matrix at 10 K is 8 times larger than the value for Ni-NPs embedded in SiOx. We studied time-dependent remanent magnetization at different temperatures. The relaxation behavior is described by a magnetic viscosity model which reflects a rather flat distribution of energy barriers. Furthermore, we investigated the effects of different field cooling processes on the magnetic properties of the embedded Ni-NPs. Exchange bias values fit to model calculations which correlate the contribution of the antiferromagnetic IrMn matrix to its grain size.

  5. Structural properties of silicon nanoparticles formed by pulsed laser ablation in liquid media

    NASA Astrophysics Data System (ADS)

    Eroshova, O. I.; Perminov, P. A.; Zabotnov, S. V.; Gongal'skii, M. B.; Ezhov, A. A.; Golovan', L. A.; Kashkarov, P. K.

    2012-11-01

    Silicon nanoparticles have been formed as a result of the irradiation of single-crystal silicon targets in distilled water and liquid nitrogen, by, respectively, picosecond and femtosecond laser pulses. The main structural properties of these nanoparticles have been investigated by atomic force microscopy, transmission electron microscopy, electron diffraction, Raman scattering, and photoluminescence spectroscopy. These particles are found to be mainly spherical. The presence of crystalline and amorphous silicon phases under picosecond ablation in water is established experimentally. Irradiation by femtosecond pulses in liquid nitrogen can yield nanoparticles smaller than 5 nm in size, which are quantum dots with a characteristic photoluminescence peak near 750 nm.

  6. Sample temperature profile during the excimer laser annealing of silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Caninenberg, M.; Verheyen, E.; Kiesler, D.; Stoib, B.; Brandt, M. S.; Benson, N.; Schmechel, R.

    2015-11-01

    Based on the heat diffusion equation we describe the temperature profile of a silicon nanoparticle thin film on silicon during excimer laser annealing using COMSOL Multiphysics. For this purpose system specific material parameters are determined such as the silicon nanoparticle melting point at 1683 K, the surface reflectivity at 248 nm of 20% and the nanoparticle thermal conductivity between 0.3 and 1.2 W/m K. To validate our model, the simulation results are compared to experimental data obtained by Raman spectroscopy, SEM microscopy and electrochemical capacitance-voltage measurements (ECV). The experimental data are in good agreement with our theoretical findings and support the validity of the model.

  7. Synthesis, characterization and functionalization of silicon nanoparticle based hybrid nanomaterials for photovoltaic and biological applications

    NASA Astrophysics Data System (ADS)

    Xu, Zejing

    Silicon nanoparticles are attractive candidates for biological, photovoltaic and energy storage applications due to their size dependent optoelectronic properties. These include tunable light emission, high brightness, and stability against photo-bleaching relative to organic dyes (see Chapter 1). The preparation and characterization of silicon nanoparticle based hybrid nanomaterials and their relevance to photovoltaic and biological applications are described. The surface-passivated silicon nanoparticles were produced in one step from the reactive high-energy ball milling (RHEBM) of silicon wafers with various organic ligands. The surface structure and optical properties of the passivated silicon nanoparticles were systematically characterized. Fast approaches for purifying and at the same time size separating the silicon nanoparticles using a gravity GPC column were developed. The hydrodynamic diameter and size distribution of these size-separated silicon nanoparticles were determined using GPC and Diffusion Ordered NMR Spectroscopy (DOSY) as fast, reliable alternative approaches to TEM. Water soluble silicon nanoparticles were synthesized by grafting PEG polymers onto functionalized silicon nanoparticles with distal alkyne or azide moieties. The surface-functionalized silicon nanoparticles were produced from the reactive high-energy ball milling (RHEBM) of silicon wafers with a mixture of either 5-chloro-1-pentyne in 1-pentyne or 1,7 octadiyne in 1-hexyne to afford air and water stable chloroalkyl or alkynyl terminated nanoparticles, respectively. Nanoparticles with the ω-chloroalkyl substituents were easily converted to ω-azidoalkyl groups through the reaction of the silicon nanoparticles with sodium azide in DMF. The azido terminated nanoparticles were then grafted with monoalkynyl-PEG polymers using a copper catalyzed alkyne-azide cycloaddition (CuAAC) reaction to afford core-shell silicon nanoparticles with a covalently attached PEG shell. Covalently

  8. Physio-chemical and antibacterial characteristics of pressure spun nylon nanofibres embedded with functional silver nanoparticles.

    PubMed

    Xu, Z; Mahalingam, S; Rohn, J L; Ren, G; Edirisinghe, M

    2015-11-01

    A novel and facile approach to prepare hybrid nanoparticle embedded polymer nanofibers using pressurised gyration is presented. Silver nanoparticles and nylon polymer were used in this work. The polymer solution's physical properties, rotating speed and the working pressure had a significant influence on the fibre diameter and the morphology. Fibres in the range of 60-500nm were spun using 10wt.%, 15wt.% and 20wt.% nylon solutions and these bead-free fibres were processed under 0.2MPa and 0.3MPa working pressure and a rotational speed of 36,000rpm. 1-4wt.% of Ag was added to these nylon solutions and in the case of wt.% fibres in the range 50-150nm were prepared using the same conditions of pressurised gyration. Successful incorporation of the Ag nanoparticles in nylon nanofibres was confirmed by using a combination of advanced microscopical techniques and Raman spectrometry was used to study the bonding characteristics of nylon and the Ag nanoparticles. Inductively coupled plasma mass spectroscopy showed a substantial concentration of Ag ions in the nylon fibre matrix which is essential for producing effective antibacterial properties. Antibacterial activity of the Ag-loaded nanofibres shows higher efficacy than nylon nanofibres for Gram-negative Escherichia coli and Pseudomonas aeruginosa microorganisms, and both Ag nanoparticles and the Ag ions were found to be the reason for enhanced cell death in the bacterial solutions. PMID:26249581

  9. Nanocomposites of silver nanoparticles embedded in glass nanofibres obtained by laser spinning

    NASA Astrophysics Data System (ADS)

    Cabal, Belén; Quintero, Félix; Díaz, Luís Antonio; Rojo, Fernando; Dieste, Oliver; Pou, Juan; Torrecillas, Ramón; Moya, José Serafín

    2013-04-01

    Nanocomposites made of non-woven glass fibres with diameters ranging from tens of nanometers up to several micrometers, containing silver nanoparticles, were successfully fabricated by the laser spinning technique. Pellets of a soda-lime silicate glass containing silver nanoparticles with varying concentrations (5 and 10 wt%) were used as a precursor. The process followed to obtain the silver nanofibres did not agglomerate significantly the metallic nanoparticles, and the average particle size is still lower than 50 nm. This is the first time that glass nanofibres containing silver nanoparticles have been obtained following a process different from electrospinning of a sol-gel, thus avoiding the limitations of this method and opening a new route to composite nanomaterials. Antibacterial efficiency of the nanosilver glass fibres, tested against one of the most common Gram negative bacteria, was greater than 99.99% compared to the glass fibres free of silver. The silver nanoparticles are well-dispersed not only on the surface but are also embedded into the uniform nanofibres, which leads to a long lasting durable antimicrobial effect. All these novel characteristics will potentially open up a whole new range of applications.

  10. Nanocomposites of silver nanoparticles embedded in glass nanofibres obtained by laser spinning.

    PubMed

    Cabal, Belén; Quintero, Félix; Díaz, Luís Antonio; Rojo, Fernando; Dieste, Oliver; Pou, Juan; Torrecillas, Ramón; Moya, José Serafín

    2013-05-01

    Nanocomposites made of non-woven glass fibres with diameters ranging from tens of nanometers up to several micrometers, containing silver nanoparticles, were successfully fabricated by the laser spinning technique. Pellets of a soda-lime silicate glass containing silver nanoparticles with varying concentrations (5 and 10 wt%) were used as a precursor. The process followed to obtain the silver nanofibres did not agglomerate significantly the metallic nanoparticles, and the average particle size is still lower than 50 nm. This is the first time that glass nanofibres containing silver nanoparticles have been obtained following a process different from electrospinning of a sol-gel, thus avoiding the limitations of this method and opening a new route to composite nanomaterials. Antibacterial efficiency of the nanosilver glass fibres, tested against one of the most common gram negative bacteria, was greater than 99.99% compared to the glass fibres free of silver. The silver nanoparticles are well-dispersed not only on the surface but are also embedded into the uniform nanofibres, which leads to a long lasting durable antimicrobial effect. All these novel characteristics will potentially open up a whole new range of applications. PMID:23535995

  11. Enhanced localized plasmonic detections using partially-embedded gold nanoparticles and ellipsometric measurements

    PubMed Central

    Moirangthem, Rakesh Singh; Yaseen, Mohammad Tariq; Wei, Pei-Kuen; Cheng, Ji-Yen; Chang, Yia-Chung

    2012-01-01

    A cost-effective, stable and ultrasensitive localized surface plasmon resonance (LSPR) sensor based on gold nanoparticles (AuNPs) partially embedded in transparent substrate is presented. Partially embedded AuNPs were prepared by thermal annealing of gold thin films deposited on glass at a temperature close to the glass transition temperature of the substrate. Annealed samples were optically characterized by using spectroscopic ellipsometry and compare with theoretical modeling to understand the optical responses from the samples. By combining the partially-embedded AuNPs substrate with a microfluidic flow cell and dove prism in an ellipsometry setup, an ultrasensitive change in the LSPR signal can be detected. The refractive index sensitivity obtained from the phase measurement is up to 1938 degrees/RIU which is several times higher than that of synthesized colloidal gold nanoparticles. The sample is further used to investigate the interactions between primary and secondary antibodies. The bio-molecular detection limit of the LSPR signal is down to 20 pM. Our proposed sensor is label free, non-destructive, with high sensitivity, low cost, and easy to fabricate. These features make it feasible for commercialization in biomedical applications. PMID:22567583

  12. Melting and Solidification Behaviour of Bi-Pb Multiphase Alloy Nanoparticles Embedded in Aluminum Matrix.

    PubMed

    Khan, Patan Yousaf; Biswas, Krishanu

    2015-01-01

    The present investigation reports the result of the investigation on the phase transformation of biphasic Bi-Pb alloy nanoparticles embedded in the aluminum matrix. The samples are prepared by rapid solidification route involving melt spinning of Al-6 wt% (Bi55.9Pb44.1) alloy on a rotating copper wheel in an argon-filled evacuated chamber. The detailed transmission electron microscope (TEM) investigation shows presence of near cuboctahedral shaped biphasic nano-inclusions consisting of the (Bi) solid solution and β, the intermediate phase. β constitutes bulk of the nanoparticle with (Bi) forming the cap. Both the phases bear distinct orientation relationship with the matrix. The compositional analysis indicates substantial increase in solid solubilities of Pb in the (Bi) and Bi in the β-phases as compared to the as-cast sample. Differential scanning calorimetric (DSC) studies indicate substantial superheating (16.4 K) of the embedded nanoparticles with appearance of sharp melting peak. The solidification is observed to be diffused, taking place over a large temperature range (344.5 K to 332 K). The in situ heating stage experiments carried out in TEM indicate formation of core shell morphology during heating with β forming the shell around (Bi). The melting starts from Al/β/(Bi) triple point and then the liquid spreads along matrix-particle interface. The solidification occurs in eutectic manner. PMID:26328350

  13. Evaluation of optical and electronic properties of silicon nano-agglomerates embedded in SRO: applying density functional theory

    PubMed Central

    2014-01-01

    In systems in atomic scale and nanoscale such as clusters or agglomerates constituted by particles from a few to less than 100 atoms, quantum confinement effects are very important. Their optical and electronic properties are often dependent on the size of the systems and the way in which the atoms in these clusters are bonded. Generally, these nanostructures display optical and electronic properties significantly different to those found in corresponding bulk materials. Silicon agglomerates embedded in silicon rich oxide (SRO) films have optical properties, which have been reported to be directly dependent on silicon nanocrystal size. Furthermore, the room temperature photoluminescence (PL) of SRO has repeatedly generated a huge interest due to its possible applications in optoelectronic devices. However, a plausible emission mechanism has not been widely accepted in the scientific community. In this work, we present a short review about the experimental results on silicon nanoclusters in SRO considering different techniques of growth. We focus mainly on their size, Raman spectra, and photoluminescence spectra. With this as background, we employed the density functional theory with a functional B3LYP and a basis set 6-31G* to calculate the optical and electronic properties of clusters of silicon (constituted by 15 to 20 silicon atoms). With the theoretical calculation of the structural and optical properties of silicon clusters, it is possible to evaluate the contribution of silicon agglomerates in the luminescent emission mechanism, experimentally found in thin SRO films. PMID:25276105

  14. Evaluation of optical and electronic properties of silicon nano-agglomerates embedded in SRO: applying density functional theory.

    PubMed

    Espinosa-Torres, Néstor D; la Luz, David Hernández-de; Flores-Gracia, José Francisco J; Luna-López, José A; Martínez-Juárez, Javier; Vázquez-Valerdi, Diana E

    2014-01-01

    In systems in atomic scale and nanoscale such as clusters or agglomerates constituted by particles from a few to less than 100 atoms, quantum confinement effects are very important. Their optical and electronic properties are often dependent on the size of the systems and the way in which the atoms in these clusters are bonded. Generally, these nanostructures display optical and electronic properties significantly different to those found in corresponding bulk materials. Silicon agglomerates embedded in silicon rich oxide (SRO) films have optical properties, which have been reported to be directly dependent on silicon nanocrystal size. Furthermore, the room temperature photoluminescence (PL) of SRO has repeatedly generated a huge interest due to its possible applications in optoelectronic devices. However, a plausible emission mechanism has not been widely accepted in the scientific community. In this work, we present a short review about the experimental results on silicon nanoclusters in SRO considering different techniques of growth. We focus mainly on their size, Raman spectra, and photoluminescence spectra. With this as background, we employed the density functional theory with a functional B3LYP and a basis set 6-31G* to calculate the optical and electronic properties of clusters of silicon (constituted by 15 to 20 silicon atoms). With the theoretical calculation of the structural and optical properties of silicon clusters, it is possible to evaluate the contribution of silicon agglomerates in the luminescent emission mechanism, experimentally found in thin SRO films. PMID:25276105

  15. Platinum nanoparticle decorated silicon nanowires for efficient solar energy conversion.

    PubMed

    Peng, Kui-Qing; Wang, Xin; Wu, Xiao-Ling; Lee, Shuit-Tong

    2009-11-01

    High-density aligned n-type silicon nanowire (SiNW) arrays decorated with discrete 5-10 nm platinum nanoparticles (PtNPs) have been fabricated by aqueous electroless Si etching followed by an electroless platinum deposition process. Coating of PtNPs on SiNW sidewalls yielded a substantial enhancement in photoconversion efficiency and an apparent energy conversion efficiency of up to 8.14% for the PtNP-decorated SiNW-based photoelectrochemical solar cell using a liquid electrolyte containing Br(-)/Br(2) redox couple. The results demonstrate PtNP-decorated SiNWs to be a promising hybrid system for solar energy conversion. PMID:19807069

  16. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    PubMed Central

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-01-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature. PMID:26681336

  17. Viscosity of magnetorheological fluids using Iron-silicon nanoparticles.

    PubMed

    Kim, Jong Hee; Kim, CheolGi; Lee, Seung Goo; Hong, Tae Min; Choi, Joon Hong

    2013-09-01

    Fe-6.5Si fine particles were mechanically fabricated by a milling method for use in magnetorheological fluids. Oleic acid was used as a surfactant for the dispersed substance for preparing the hydrophobic fluid with silicon oil as a dispersing medium. Further, oleic acid and sodium dodecyl benzene sulfonate were used as surfactants, forming a bilayer structure, for preparing the hydrophilic fluid with polyethylene glycol as a dispersing medium. The adsorption of oleic acid onto the Fe-Si particles was achieved by oxidizing the particle surface with trimethylamine N-oxide dihydrate. In order to make a comparative examination of the fluid properties, ferromagnetic nanoparticles were synthesized by chemical precipitation and the subsequent process was accompanied under the same conditions as applied for the magnetorheological fluid. The fluid particles were characterized by magnetization measurements. The viscosity of the fluids was obtained at various concentrations under an external field. The viscosity values of the magnetorheological fluid were higher than those of the ferromagnetic fluid. Moreover, they increased considerably by using silicon oil as the dispersing medium as well as under an applied magnetic field and at higher fluid concentrations. The magnetorheological fluids may be effectively resistant to a strong impact from outside when the appropriate fluid concentration is used and a magnetic field is applied for increasing the shear strength of the fluids. PMID:24205598

  18. Cavity cooling of free silicon nanoparticles in high vacuum

    PubMed Central

    Asenbaum, Peter; Kuhn, Stefan; Nimmrichter, Stefan; Sezer, Ugur; Arndt, Markus

    2013-01-01

    Laser cooling has given a boost to atomic physics throughout the last 30 years, as it allows one to prepare atoms in motional states, which can only be described by quantum mechanics. Most methods rely, however, on a near-resonant and cyclic coupling between laser light and well-defined internal states, which has remained a challenge for mesoscopic particles. An external cavity may compensate for the lack of internal cycling transitions in dielectric objects and it may provide assistance in the cooling of their centre-of-mass state. Here we demonstrate cavity cooling of the transverse kinetic energy of silicon nanoparticles freely propagating in high vacuum (<10−8 mbar). We create and launch them with longitudinal velocities down to v≤1 m s−1 using laser-induced ablation of a pristine silicon wafer. Their interaction with the light of a high-finesse infrared cavity reduces their transverse kinetic energy by up to a factor of 30. PMID:24193438

  19. Enhanced photoluminescence of porous silicon nanoparticles coated by bioresorbable polymers

    NASA Astrophysics Data System (ADS)

    Gongalsky, Maxim B.; Kharin, Alexander Yu; Osminkina, Liubov A.; Timoshenko, Victor Yu; Jeong, Jinyoung; Lee, Han; Chung, Bong Hyun

    2012-08-01

    A significant enhancement of the photoluminescence (PL) efficiency is observed for aqueous suspensions of porous silicon nanoparticles (PSiNPs) coated by bioresorbable polymers, i.e., polylactic-co-glycolic acid (PLGA) and polyvinyl alcohol (PVA). PSiNPs with average size about 100 nm prepared by mechanical grinding of electrochemically etched porous silicon were dispersed in water to prepare the stable suspension. The inner hydrophobic PLGA layer prevents the PSiNPs from the dissolution in water, while the outer PVA layer makes the PSiNPs hydrophilic. The PL quantum yield of PLGA/PVA-coated PSiNPs was found to increase by three times for 2 weeks of the storage in water. The observed effect is explained by taking into account both suppression of the dissolution of PSiNPs in water and a process of the passivation of nonradiative defects in PSiNPs. The obtained results are interesting in view of the potential applications of PSiNPs in bioimaging.

  20. Drug permeation across intestinal epithelial cells using porous silicon nanoparticles.

    PubMed

    Bimbo, Luis M; Mäkilä, Ermei; Laaksonen, Timo; Lehto, Vesa-Pekka; Salonen, Jarno; Hirvonen, Jouni; Santos, Hélder A

    2011-04-01

    Mesoporous silicon particles hold great potential in improving the solubility of otherwise poorly soluble drugs. To effectively translate this feature into the clinic, especially via oral or parenteral administration, a thorough understanding of the interactions of the micro- and nanosized material with the physiological environment during the delivery process is required. In the present study, the behaviour of thermally oxidized porous silicon particles of different sizes interacting with Caco-2 cells (both non-differentiated and polarized monolayers) was investigated in order to establish their fate in a model of intestinal epithelial cell barrier. Particle interactions and TNF-α were measured in RAW 264.7 macrophages, while cell viabilities, reactive oxygen species and nitric oxide levels, together with transmission electron microscope images of the polarized monolayers, were assessed with both the Caco-2 cells and RAW 264.7 macrophages. The results showed a concentration and size dependent influence on cell viability and ROS-, NO- and TNF-α levels. There was no evidence of the porous nanoparticles crossing the Caco-2 cell monolayers, yet increased permeation of the loaded poorly soluble drug, griseofulvin, was shown. PMID:21194747

  1. A novel C-shaped, gold nanoparticle coated, embedded polymer waveguide for localized surface plasmon resonance based detection.

    PubMed

    Prabhakar, Amit; Mukherji, Soumyo

    2010-12-21

    In this study, a novel embedded optical waveguide based sensor which utilizes localized surface plasmon resonance of gold nanoparticles coated on a C-shaped polymer waveguide is being reported. The sensor, as designed, can be used as an analysis chip for detection of minor variations in the refractive index of its microenvironment, which makes it suitable for wide scale use as an affinity biosensor. The C-shaped waveguide coupled with microfluidic channel was fabricated by single step patterning of SU8 on an oxidized silicon wafer. The absorbance due to the localized surface plasmon resonance (LSPR) of SU8 waveguide bound gold nano particle (GNP) was found to be linear with refractive index changes between 1.33 and 1.37. A GNP coated C-bent waveguide of 200 μ width with a bend radius of 1 mm gave rise to a sensitivity of ~5 ΔA/RIU at 530 nm as compared to the ~2.5 ΔA/RIU (refractive index units) of the same dimension bare C-bend SU8 waveguide. The resolution of the sensor probe was ~2 × 10(-4) RIU. PMID:20944850

  2. Simultaneous SERS and surface-enhanced fluorescence from dye-embedded metal core-shell nanoparticles.

    PubMed

    Zhou, Yan; Zhang, Peng

    2014-05-21

    We demonstrate a methodology to prepare Au-core-Ag-shell nanoparticles displaying both SERS and surface-enhanced fluorescence (SEF) activities simultaneously by embedding dye molecules between the core and the shell. Polyelectrolytes are used to adjust the spacing and the dye position between the core and the shell. Layer-by-layer polyelectrolyte deposition can serve as an effective and flexible way to introduce various types of dye molecules into the nanostructures. Results from the spectral measurements shed light on the intricacy between SERS and SEF. PMID:24695881

  3. Alloyed nanoparticle-embedded alumina nanocermet film: A new attempt to improve the thermotolerance

    NASA Astrophysics Data System (ADS)

    Tu, C. J.; Gao, J. H.; Hui, S.; Lou, D.; Zhang, H. L.; Liang, L. Y.; Jin, A. P.; Zou, Y. S.; Cao, H. T.

    2015-03-01

    This paper focuses on the enhancement of thermal stability of Ag-Al2O3 nanocermet films by means of alloying of Ag nanoparticles with Al element. The optical analysis demonstrated the AgAl embedded Al2O3 cermet films (namely, AgAl-Al2O3) possess excellent thermal tolerance even at 500 °C for 260 h under nitrogen ambient. The evolution of microstructural and chemical properties of Al2O3/AgAl-Al2O3/Al2O3 stack layers during the annealing process was comprehensively investigated, in order to grasp the thermal stability mechanism. It is believed that the enhanced thermal stability was ascribed to the formation of fresh alumina as capping layer riveted on the Ag nanoparticles surfaces, which acted as the pinning points to prevent silver element from migrating so as to maintain the expected optical properties.

  4. Towards optimization and characterization of dye-embedded gold nanoparticle clusters for multiplexed optical imaging

    NASA Astrophysics Data System (ADS)

    McDonald, M. A.; Hight Walker, A. R.

    2009-02-01

    Metallic nanoparticle clusters coupling strong surface plasmons with a Raman reporter molecule have been developed for application in multiplexed optical imaging. Of interest to our work is the ability of the agents to serve as surface-enhanced Raman spectroscopy (SERS) probes. We present the seed-mediated synthesis and characterization of rhodamine B isothiocyante Au nanoparticle clusters (RhB-AuNPCs). RhB-AuNPCs are anisotropic structures which contain the Raman reporter, RhB, embedded between a gold aggregate core and gold surface layer. In contrast to typical SERS studies, the Raman signal originates from the probe (RhB-AuNPCs) and not from RhB incubated with a noble metal colloid. Characterization of the probes' optical properties is presented. The overall goal of our study is to prepare probes that may be used for the identification and spectroscopic labeling of multiple molecular biomarkers utilizing SERS imaging.

  5. Enhanced resistive switching effect in Ag nanoparticle embedded BaTiO{sub 3} thin films

    SciTech Connect

    Au, K.; Wang, Juan; Bao, Z. Y.; Dai, J. Y.; Gao, X. S.; Liu, J. M.

    2013-07-14

    Ag nanoparticle (NP) embedded BaTiO{sub 3} (BTO) thin films on SrRuO{sub 3}-coated SrTiO{sub 3} (STO) substrates are prepared by the integrated nanocluster beam deposition and laser-molecular beam epitaxy. Enhanced resistive switching, up to an ON/OFF ration of 10{sup 4}, has been achieved at low switching voltage (less than 1 V) without a forming voltage. These characteristics make such nanocomposite film very promising for application of low voltage non-volatile random access memory. The enhanced resistive switching effect may be attributed to the charge storage effect of the Ag nanoparticles and easy formation of Ag filament inside the BTO film.

  6. Pd nanoparticles embedded into a metal-organic framework: synthesis, structural characteristics, and hydrogen sorption properties.

    PubMed

    Zlotea, Claudia; Campesi, Renato; Cuevas, Fermin; Leroy, Eric; Dibandjo, Philippe; Volkringer, Christophe; Loiseau, Thierry; Férey, Gérard; Latroche, Michel

    2010-03-10

    The metal-organic framework MIL-100(Al) has been used as a host to synthesize Pd nanoparticles (around 2.0 nm) embedded within the pores of the MIL, showing one of the highest metal contents (10 wt %) without degradation of the porous host. Textural properties of MIL-100(Al) are strongly modified by Pd insertion, leading to significant changes in gas sorption properties. The loss of excess hydrogen storage at low temperature can be correlated with the decrease of the specific surface area and pore volume after Pd impregnation. At room temperature, the hydrogen uptake in the composite MIL-100(Al)/Pd is almost twice that of the pristine material. This can be only partially accounted by Pd hydride formation, and a "spillover" mechanism is expected to take place promoting the dissociation of molecular hydrogen at the surface of the metal nanoparticles and the diffusion of monatomic hydrogen into the porosity of the host metal-organic framework. PMID:20155921

  7. Preparation and antibacterial performance testing of Ag nanoparticles embedded biological materials

    NASA Astrophysics Data System (ADS)

    Li, Xiaoyun; Gao, Guanhui; Sun, Chengjun; Zhu, Yaoyao; Qu, Lingyun; Jiang, Fenghua; Ding, Haibing

    2015-03-01

    In this study, we developed an environmentally friendly chemistry strategy to synthesize Ag nanoparticles (Ag-NPs) embedded biological material, powdered mussel shell (PMS). With the PMS as scaffolds and surfactant, Ag nanoparticles of controllable size dispersed uniformly on it via liquid chemical reduction approach. Morphologies and characteristics of synthesized Ag-NPs/PMS hybrids were analyzed with TEM, SEM and XPS. Antibacterial properties were investigated with Gram-positive bacteria (Arthrobacter sulfureus (A. sulfureus) YACS14, Staphylococcus aureus (S. aureus)) and Gram-negative bacteria (Vibrio anguillarum (V. anguillarum) MVM425, Escherichia coli (E. coli)). The antimicrobial results illustrated that Ag-NPs/PMS composites have antibacterial effect on both sea water and fresh water bacteria with a better effect on sea water bacteria. The degree of antibacterial effect is directly related to the amount of Ag released from Ag-NPs/PMS.

  8. Hydrothermal Synthesis and Processing of Barium Titanate Nanoparticles Embedded in Polymer Films.

    PubMed

    Toomey, Michael D; Gao, Kai; Mendis, Gamini P; Slamovich, Elliott B; Howarter, John A

    2015-12-30

    Barium titanate nanoparticles embedded in flexible polymer films were synthesized using hydrothermal processing methods. The resulting films were characterized with respect to material composition, size distribution of nanoparticles, and spatial location of particles within the polymer film. Synthesis conditions were varied based on the mechanical properties of the polymer films, ratio of polymer to barium titanate precursors, and length of aging time between initial formulations of the solution to final processing of nanoparticles. Block copolymers of poly(styrene-co-maleic anhydride) (SMAh) were used to spatially separate titanium precursors based on specific chemical interactions with the maleic anhydride moiety. However, the glassy nature of this copolymer restricted mobility of the titanium precursors during hydrothermal processing. The addition of rubbery butadiene moieties, through mixing of the SMAh with poly(styrene-butadiene-styrene) (SBS) copolymer, increased the nanoparticle dispersion as a result of greater diffusivity of the titanium precursor via higher mobility of the polymer matrix. Additionally, an aminosilane was used as a means to retard cross-linking in polymer-metalorganic solutions, as the titanium precursor molecules were shown to react and form networks prior to hydrothermal processing. By adding small amounts of competing aminosilane, excessive cross-linking was prevented without significantly impacting the quality and composition of the final barium titanate nanoparticles. X-ray diffraction and X-ray photoelectron spectroscopy were used to verify nanoparticle compositions. Particle sizes within the polymer films were measured to be 108 ± 5 nm, 100 ± 6 nm, and 60 ± 5 nm under different synthetic conditions using electron microscopy. Flexibility of the films was assessed through measurement of the glass transition temperature using dynamic mechanical analysis. Dielectric permittivity was measured using an impedance analyzer. PMID

  9. Embedded silica nanoparticles in poly(caprolactone) nanofibrous scaffolds enhanced osteogenic potential for bone tissue engineering.

    PubMed

    Ganesh, Nitya; Jayakumar, Rangasamy; Koyakutty, Manzoor; Mony, Ullas; Nair, Shantikumar V

    2012-09-01

    Poly(caprolactone) (PCL) has been frequently considered for bone tissue engineering because of its excellent biocompatibility. A drawback, however, of PCL is its inadequate mechanical strength for bone tissue engineering and its inadequate bioactivity to promote bone tissue regeneration from mesenchymal stem cells. To correct this deficiency, this work investigates the addition of nanoparticles of silica (nSiO(2)) to the scaffold to take advantage of the known bioactivity of silica as an osteogenic material and also to improve the mechanical properties through nanoscale reinforcement of the PCL fibers. The nanocomposite scaffolds and the pristine PCL scaffolds were evaluated physicochemically, mechanically, and biologically in the presence of human mesenchymal stem cells (hMSCs). The results indicated that, when the nanoparticles of size approximately 10 nm (concentrations of 0.5% and 1% w/v) were embedded within, or attached to, the PCL nanofibers, there was a substantial increase in scaffold strength, protein adsorption, and osteogenic differentiation of hMSCs. These nSiO(2) nanoparticles, when directly added to the cells evidently pointed to ingestion of these particles by the cells followed by cell death. The polymer nanofibers appeared to protect the cells by preventing ingestion of the silica nanoparticles, while at the same time adequately exposing them on fiber surfaces for their desired bioactivity. PMID:22725098

  10. Aggregation-Induced Emission Luminogen-Embedded Silica Nanoparticles Containing DNA Aptamers for Targeted Cell Imaging.

    PubMed

    Wang, Xiaoyan; Song, Panshu; Peng, Lu; Tong, Aijun; Xiang, Yu

    2016-01-13

    Conventional fluorophores usually undergo aggregation-caused quenching (ACQ), which limits the loading amount of these fluorophores in nanoparticles for bright fluorescence imaging. On the contrary, fluorophores with aggregation-induced emission (AIE) characteristics are strongly fluorescent in their aggregate states and have been an ideal platform for developing highly fluorescent nanomaterials, such as fluorescent silica nanoparticles (FSNPs). In this work, AIE luminogens based on salicylaldehyde hydrazones were embedded in silica nanoparticles through a facile noncovalent approach, which afforded AIE-FSNPs emitting much brighter fluorescence than that of some commercial fluorescein-doped silica and polystyrene nanoparticles. These AIE-FSNPs displaying multiple fluorescence colors were fabricated by a general method, and they underwent much less fluorescence variation due to environmental pH changes compared with fluorescein-hybridized FSNPs. In addition, a DNA aptamer specific to nucleolin was functionalized on the surface of AIE-FSNPs for targeted cell imaging. Fluorescent microscopy and flow cytometry studies both revealed highly selective fluorescence staining of MCF-7 (a cancer cell line with nucleolin overexpression) over MCF-10A (normal) cells by the aptamer-functionalized AIE-FSNPs. The fluorescence imaging in different color channels was achieved using AIE-FSNPs containing each of the AIE luminogens, as well as photoactivatable fluorescent imaging of target cells by the caged AIE fluorophore. PMID:26653325

  11. Synthesis and characterization of nano ZnO, nano Ag/ZnO composite & nano-particles embedded polymers

    NASA Astrophysics Data System (ADS)

    Are, Thilak Reddy

    Zinc oxide and silver/zinc oxide nano particles were synthesized by a simple precipitation method in the presence of polyvinylpyrrolidone (PVP). The presence of polyvinylpyrrolidone prevents agglomeration and allows the formation of nano sized particles. Characterization of synthesized nano particles were carried out using X-ray powder diffraction, differential scanning calorimetry, scanning electron microscopy, and the average sizes were determined by zeta seizer. The X-ray diffraction shows that the prepared particles were poorly crystalline. The DSC results show that the prepared particles are highly stable and no phase changes were observed when heated from room temperature to 500°C. Scanning electron microscopic observation shows that the particles are uniformly distributed with similar shape. Zeta seizer results show that the prepared particles are nano-particles with average size of about 100 nm. The prepared Zinc oxide nano particles were embedded into the polycaprolactone (PCL) polymer to study the effect of embedding zinc oxide nanoparticle on PCL crystallinity and mechanical properties. ZnO nano particles were successfully embedded into the polymer using in-situ and non-in-situ embedding processes. Characterization of PCL embedded with ZnO nanoparticles was performed by X-ray diffraction technique and scanning electron microscope. Crystallinity studies were done by using differential scanning calorimetry and the results show that the polymer embedded using an in situ process showed a decrease in crystallinity compared to the polymer embedded using a non-insitu process.

  12. Phase decomposition of AuFe alloy nanoparticles embedded in silica matrix under swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Pannu, Compesh; Bala, Manju; Singh, U. B.; Srivastava, S. K.; Kabiraj, D.; Avasthi, D. K.

    2016-07-01

    AuFe alloy nanoparticles embedded in silica matrix are synthesized using atom beam sputtering technique and subsequently irradiated with 100 MeV Au ions at various fluences ranging from 1 × 1013 to 6 × 1013 ions/cm2. The X-ray diffraction, absorption spectroscopy, X-ray photo electron spectroscopy and transmission electron microscopy results show that swift heavy ion irradiation leads to decomposition of AuFe alloy nanoparticles from surface region and subsequent reprecipitation of Au and Fe nanoparticles occur. The process of phase decomposition and reprecipitation of individual element nanoparticles is explained on the basis of inelastic thermal spike model.

  13. Investigations of segregation phenomena in highly strained Mn-doped Ge wetting layers and Ge quantum dots embedded in silicon

    SciTech Connect

    Prestat, E. Porret, C.; Favre-Nicolin, V.; Tainoff, D.; Boukhari, M.; Bayle-Guillemaud, P.; Jamet, M.; Barski, A.

    2014-03-10

    In this Letter, we investigate manganese diffusion and the formation of Mn precipitates in highly strained, few monolayer thick, Mn-doped Ge wetting layers and nanometric size Ge quantum dot heterostructures embedded in silicon. We show that in this Ge(Mn)/Si system manganese always precipitates and that the size and the position of Mn clusters (precipitates) depend on the growth temperature. At high growth temperature, manganese strongly diffuses from germanium to silicon, whereas decreasing the growth temperature reduces the manganese diffusion. In the germanium quantum dots layers, Mn precipitates are detected, not only in partially relaxed quantum dots but also in fully strained germanium wetting layers between the dots.

  14. The silicon-glass microreactor with embedded sensors—technology and results of preliminary qualitative tests, toward intelligent microreaction plant

    NASA Astrophysics Data System (ADS)

    Knapkiewicz, P.

    2013-03-01

    The technology and preliminary qualitative tests of silicon-glass microreactors with embedded pressure and temperature sensors are presented. The concept of microreactors for leading highly exothermic reactions, e.g. nitration of hydrocarbons, and design process-included computer-aided simulations are described in detail. The silicon-glass microreactor chip consisting of two micromixers (multistream micromixer), reaction channels, cooling/heating chambers has been proposed. The microreactor chip was equipped with a set of pressure and temperature sensors and packaged. Tests of mixing quality, pressure drops in channels, heat exchange efficiency and dynamic behavior of pressure and temperature sensors were documented. Finally, two applications were described.

  15. Aluminothermic reduction enabled synthesis of silicon hollow microspheres from commercialized silica nanoparticles for superior lithium storage.

    PubMed

    Zhou, Zheng-Wei; Liu, Yi-Tao; Xie, Xu-Ming; Ye, Xiong-Ying

    2016-06-28

    We report the aluminothermic reduction enabled synthesis of silicon hollow microspheres from commercialized silica nanoparticles by controlled transformation and organization. The synergistically integrated merits of a simple process and delicate structural design lay a basis for developing an industrially viable silicon anode with optimized electrochemical performances. PMID:27302245

  16. A dimensional comparison between embedded 3D-printed and silicon microchannels

    NASA Astrophysics Data System (ADS)

    O'Connor, J.; Punch, J.; Jeffers, N.; Stafford, J.

    2014-07-01

    The subject of this paper is the dimensional characterization of embedded microchannel arrays created using contemporary 3D-printing fabrication techniques. Conventional microchannel arrays, fabricated using deep reactive ion etching techniques (DRIE) and wet-etching (KOH), are used as a benchmark for comparison. Rectangular and trapezoidal cross-sectional shapes were investigated. The channel arrays were 3D-printed in vertical and horizontal directions, to examine the influence of print orientation on channel characteristics. The 3D-printed channels were benchmarked against Silicon channels in terms of the following dimensional characteristics: cross-sectional area (CSA), perimeter, and surface profiles. The 3D-printed microchannel arrays demonstrated variances in CSA of 6.6-20% with the vertical printing approach yielding greater dimensional conformity than the horizontal approach. The measured CSA and perimeter of the vertical channels were smaller than the nominal dimensions, while the horizontal channels were larger in both CSA and perimeter due to additional side-wall roughness present throughout the channel length. This side-wall roughness caused significant shape distortion. Surface profile measurements revealed that the base wall roughness was approximately the resolution of current 3D-printers. A spatial periodicity was found along the channel length which appeared at different frequencies for each channel array. This paper concludes that vertical 3D-printing is superior to the horizontal printing approach, in terms of both dimensional fidelity and shape conformity and can be applied in microfluidic device applications.

  17. Preparation and Surface Layer Modification of Silicon Nanoparticles Dispersed in 2-Propanol

    NASA Astrophysics Data System (ADS)

    Zhu, Yong; S, Iwasaki; K, Kimura; Zhang, Li-de

    1998-12-01

    Silicon nanoparticles dispersed in 2-propanol were prepared by using an arc plasma with gas flow method in a new designed home-made apparatus. The particles are composed of silicon crystal core covered by oxidized amorphous silicon shell. The composition of the particle surface layer can be modified by preparing the sample in different atmosphere. The particles can be also obtained with different core composition and different size which we need.

  18. Oxidation of silicon nanoparticles produced by nanosecond laser ablation in liquids

    NASA Astrophysics Data System (ADS)

    Vaccaro, L.; Camarda, P.; Messina, F.; Buscarino, G.; Agnello, S.; Gelardi, F. M.; Cannas, M.; Boscaino, R.

    2014-10-01

    We investigated nanoparticles produced by laser ablation of silicon in water by the fundamental harmonic (1064 nm) of a ns pulsed Nd:YAG. The silicon oxidation is evidenced by IR absorption features characteristic of amorphous SiO2 (silica). This oxide is highly defective and manifests a luminescence activity under UV excitation: two emission bands at 2.7 eV and 4.4 eV are associated with the twofold coordinated silicon, =SiO••.

  19. Luminescence behavior of silicon and carbon nanoparticles dispersed in low-polar liquids

    PubMed Central

    2012-01-01

    A comparative photoluminescence analysis of as-prepared and chemically modified (by alkyl chains -C18H37) silicon and carbon nanoparticles dispersed in low-polar liquids is reported. Influence of the low-polar liquid nature and ambient temperature on photoluminescence of the nanoparticles has been investigated from the point of view of their possible application as thermal nanoprobes. PMID:22748140

  20. Electrospun aligned PLGA and PLGA/gelatin nanofibers embedded with silica nanoparticles for tissue engineering.

    PubMed

    Mehrasa, Mohammad; Asadollahi, Mohammad Ali; Ghaedi, Kamran; Salehi, Hossein; Arpanaei, Ayyoob

    2015-08-01

    Aligned poly lactic-co-glycolic acid (PLGA) and PLGA/gelatin nanofibrous scaffolds embedded with mesoporous silica nanoparticles (MSNPs) were fabricated using electrospinning method. The mean diameters of nanofibers were 641±24 nm for the pure PLGA scaffolds vs 418±85 nm and 267±58 nm for the PLGA/10 wt% MSNPs and the PLGA/gelatin/10 wt% MSNPs scaffolds, respectively. The contact angle measurement results (102°±6.7 for the pure PLGA scaffold vs 81°±6.8 and 18°±8.7 for the PLGA/10 wt% MSNPs and the PLGA/gelatin/10 wt% MSNPs scaffolds, respectively) revealed enhanced hydrophilicity of scaffolds upon incorporation of gelatin and MSNPs. Besides, embedding the scaffolds with MSNPs resulted in improved tensile mechanical properties. Cultivation of PC12 cells on the scaffolds demonstrated that introduction of MSNPs into PLGA and PLGA/gelatin matrices leads to the improved cell attachment and proliferation as well as long cellular processes. DAPI staining results indicated that cell proliferations on the PLGA/10 wt% MSNPs and the PLGA/gelatin/10 wt% MSNPs scaffolds were strikingly (nearly 2.5 and 3 folds, respectively) higher than that on the aligned pure PLGA scaffolds. These results suggest superior properties of silica nanoparticles-incorporated PLGA/gelatin eletrospun nanofibrous scaffolds for the stem cell culture and tissue engineering applications. PMID:26045092

  1. The effects of titania nanotubes with embedded silver oxide nanoparticles on bacteria and osteoblasts.

    PubMed

    Gao, Ang; Hang, Ruiqiang; Huang, Xiaobo; Zhao, Lingzhou; Zhang, Xiangyu; Wang, Lin; Tang, Bin; Ma, Shengli; Chu, Paul K

    2014-04-01

    A versatile strategy to endow biomaterials with long-term antibacterial ability without compromising the cytocompatibility is highly desirable to combat biomaterial related infection. TiO2 nanotube (NT) arrays can significantly enhance the functions of many cell types including osteoblasts thus having promising applications in orthopedics, orthodontics, as well as other biomedical fields. In this study, TiO2 NT arrays with Ag2O nanoparticle embedded in the nanotube wall (NT-Ag2O arrays) are prepared on titanium (Ti) by TiAg magnetron sputtering and anodization. Well-defined NT arrays containing Ag concentrations in a wide range from 0 to 15 at % are formed. Ag incorporation has little influence on the NT diameter, but significantly decreases the tube length. Crystallized Ag2O nanoparticles with diameters ranging from 5 nm to 20 nm are embedded in the amorphous TiO2 nanotube wall and this unique structure leads to controlled release of Ag(+) that generates adequate antibacterial activity without showing cytotoxicity. The NT-Ag2O arrays can effectively kill Escherichia coli and Staphylococcus aureus even after immersion for 28 days, demonstrating the long lasting antibacterial ability. Furthermore, the NT-Ag2O arrays have no appreciable influence on the osteoblast viability, proliferation, and differentiation compared to the Ag free TiO2 NT arrays. Ag incorporation even shows some favorable effects on promoting cell spreading. The technique reported here is a versatile approach to develop biomedical coatings with different functions. PMID:24529392

  2. DRIE process optimization to fabricate vertical silicon nanowires using gold nanoparticles as masks

    NASA Astrophysics Data System (ADS)

    Bui, Thanh Tung; Phuc Tu, Hoan; Chien Dang, Mau

    2015-12-01

    Silicon nanowires have applications in various fields, e.g. vertical transistors, chemical or biological sensors, energy conversion, and storage devices. So far they have typically been obtained by bottom-up methods such as vapor-liquid-solid (VLS) synthesis, starting from metal nanoparticles. In this study, silicon nanowires are fabricated by dry reactive-ion etching using gold nanoparticles as a mask. Starting with the Bosch process, the cycle of SF6 plasma etching and C4F8 plasma deposition was optimized to control the quality of the resulting silicon nanowires.

  3. Metal oxide nanoparticles embedded in rare-earth matrix for low temperature thermal imaging applications

    NASA Astrophysics Data System (ADS)

    Rauwel, E.; Galeckas, A.; Rauwel, P.; Hansen, P.-A.; Wragg, D.; Nilsen, O.; Fjellvåg, H.

    2016-05-01

    We report on the synthesis and characterization of nanocomposites comprising of oxide nanoparticles (NPs) (ZnO, CaHfO3 and SrHfO3) embedded in rare-earth oxide (Eu2O3, Nd2O3) matrices by using atomic layer deposition. The different oxide surroundings allowed highlighting the role of interface defects in the recombination processes of charge carriers in the NPs. We provide a comparative analysis of optical absorption and emission properties of the constituents: thin films, free-standing and embedded NPs, and discuss the intrinsic and extrinsic nature of the luminescent sites in different nanocomposites. The photoluminescence properties of ZnO nanocomposites are clearly distinguishable from those of free-standing NPs in terms of overall quantum efficiency as well as intensity ratios of the characteristic blue and green emission bands associated with radiative transitions involving excitons and intrinsic defects, respectively. In contrast to PL enhancement due to surface-passivating effect of the surrounding media in the case of ZnO nanocomposites, the embedment of hafnia perovskites into oxide matrices generally leads to suppressed luminescence in the visible range, thus confirming its extrinsic, surface-defect related nature.

  4. Electron emission of Au nanoparticles embedded in ZnO for highly conductive oxide

    SciTech Connect

    Huang, Po-Shun; Lee, Jung-Kun; Hoe Kim, Dong

    2014-04-07

    We investigated the effect of embedded Au nanoparticles (Au NPs) on electrical properties of zinc oxide (ZnO) for highly conductive oxide semiconductor. Au NPs in ZnO films influenced both the structural and electrical properties of the mixture films. The electrical resistivity decreases by as much as five orders of magnitude. This is explained by the electron emission from Au NPs to the ZnO matrix. Temperature-dependent Hall effect measurements show that an electron emission mechanism changes from tunneling to thermionic emission at T = 180 K. The electron mobility in the mixture film is mainly limited by the grain boundaries at lower temperature (80-180 K), and the Au/ZnO heterogeneous interface at higher temperature (180-340 K). In addition to the electron emission, embedded Au NPs alter the ZnO matrix microstructure and improve the electron mobility. Compared to the undoped ZnO film, the carrier concentration of the Au NP-embedded ZnO film can be increased by as much as six orders of magnitude with a small change in the carrier mobility. This result suggests a way to circumvent the inherent tradeoff between the carrier concentration and the carrier mobility in transparent conductive oxide (TCO) materials.

  5. Stabilization of mid-sized silicon nanoparticles by functionalization with acrylic acid

    NASA Astrophysics Data System (ADS)

    Bywalez, Robert; Karacuban, Hatice; Nienhaus, Hermann; Schulz, Christof; Wiggers, Hartmut

    2012-01-01

    We present an enhanced method to form stable dispersions of medium-sized silicon nanoparticles for solar cell applications by thermally induced grafting of acrylic acid to the nanoparticle surface. In order to confirm their covalent attachment on the silicon nanoparticles and to assess the quality of the functionalization, X-ray photoelectron spectroscopy and diffuse reflectance infrared Fourier spectroscopy measurements were carried out. The stability of the dispersion was elucidated by dynamic light scattering and Zeta-potential measurements, showing no sign of degradation for months.

  6. Ag nanoparticles-embedded surface plasmonic InGaN-based solar cells via scattering and localized field enhancement.

    PubMed

    Shim, Jae-Phil; Choi, Sang-Bae; Kong, Duk-Jo; Seo, Dong-Ju; Kim, Hyung-Jun; Lee, Dong-Seon

    2016-07-11

    Ag nanoparticles are embedded in intentionally etched micro-circle p-GaN holes by means of a thermal agglomeration process to enhance the light absorption efficiency in InGaN/GaN multi-quantum-well (MQW) solar cells. The Ag nanoparticles are theoretically and experimentally verified to generate the plasmon light scattering and the localized field enhancement near the MQW absorption layer. The external quantum efficiency enhancement at a target wavelength region is demonstrated by matching the plasmon resonance of Ag nanoparticles, resulting in a Jsc improvement of 9.1%. Furthermore, the Ag-nanoparticle-embedded InGaN solar cell is effectively fabricated considering the carrier extraction that more than 70% of F.F. and 2.2 V of high Voc are simultaneously attained. PMID:27410903

  7. Small palladium islands embedded in palladium-tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction

    NASA Astrophysics Data System (ADS)

    Hu, Guangzhi; Nitze, Florian; Gracia-Espino, Eduardo; Ma, Jingyuan; Barzegar, Hamid Reza; Sharifi, Tiva; Jia, Xueen; Shchukarev, Andrey; Lu, Lu; Ma, Chuansheng; Yang, Guang; Wågberg, Thomas

    2014-10-01

    The sluggish kinetics of the oxygen reduction reaction at the cathode side of proton exchange membrane fuel cells is one major technical challenge for realizing sustainable solutions for the transportation sector. Finding efficient yet cheap electrocatalysts to speed up this reaction therefore motivates researchers all over the world. Here we demonstrate an efficient synthesis of palladium-tungsten bimetallic nanoparticles supported on ordered mesoporous carbon. Despite a very low percentage of noble metal (palladium:tungsten=1:8), the hybrid catalyst material exhibits a performance equal to commercial 60% platinum/Vulcan for the oxygen reduction process. The high catalytic efficiency is explained by the formation of small palladium islands embedded at the surface of the palladium-tungsten bimetallic nanoparticles, generating catalytic hotspots. The palladium islands are ~1 nm in diameter, and contain 10-20 palladium atoms that are segregated at the surface. Our results may provide insight into the formation, stabilization and performance of bimetallic nanoparticles for catalytic reactions.

  8. Flexible conductive nanocellulose combined with silicon nanoparticles and polyaniline.

    PubMed

    Park, Minsung; Lee, Dajung; Shin, Sungchul; Kim, Hyun-Joong; Hyun, Jinho

    2016-04-20

    Here we describe a unique conductive bacterial cellulose (BC) composite with silicon nanoparticles (SiNPs) and polyaniline. BC was used as a template for binding SiNPs resulting in a very promising anode material for Li-ion rechargeable batteries that showed a high specific capacity. The surfaces of the SiNPs were modified with phytic acid to enhance the binding of aniline monomer to the surface. A conformal coating of polyaniline (PANi) was formed on the modified SiNPs by in situ polymerization of aniline monomers. We also found that the phytic acid on the SiNPs was critical to ensure encapsulation of SiNPs with PANi. In addition, the phosphoric acid-tagged surface of the SiNPs enhanced the adhesion of SiNPs to the BC fibers. The resulting three dimensional network of BC was flexible and provided stress dissipation in the conductive BC composites. Flexural testing of conductive BC composites showed stable electrical conductivity even after repetitive bending over 100 times. PMID:26876826

  9. Lithiation of silicon nanoparticles confined in carbon nanotubes.

    PubMed

    Yu, Wan-Jing; Liu, Chang; Hou, Peng-Xiang; Zhang, Lili; Shan, Xu-Yi; Li, Feng; Cheng, Hui-Ming

    2015-05-26

    Silicon has the highest theoretical lithium storage capacity of all materials at 4200 mAh/g; therefore, it is considered to be a promising candidate as the anode of high-energy-density lithium-ion batteries (LIBs). However, serious volume changes caused by lithium insertion/deinsertion lead to a rapid decay of the performance of the Si anode. Here, a Si nanoparticle (NP)-filled carbon nanotube (CNT) material was prepared by chemical vapor deposition, and a nanobattery was constructed inside a transmission electron microscope (TEM) using the Si NP-filled CNT as working electrode to directly investigate the structural change of the Si NPs and the confinement effect of the CNT during the lithiation and delithiation processes. It is found that the volume expansion (∼180%) of the lithiated Si NPs is restricted by the wall of the CNTs and that the CNT can accommodate this volume expansion without breaking its tubular structure. The Si NP-filled CNTs showed a high reversible lithium storage capacity and desirable high rate capability, because the pulverization and exfoliation of the Si NPs confined in CNTs were efficiently prevented. Our results demonstrate that filling CNTs with high-capacity active materials is a feasible way to make high-performance LIB electrode materials, taking advantage of the unique confinement effect and good electrical conductivity of the CNTs. PMID:25869474

  10. Structure and magnetism in Fe/FexPd1-x core/shell nanoparticles formed by alloying in Pd-embedded Fe nanoparticles

    NASA Astrophysics Data System (ADS)

    Baker, S. H.; Lees, M.; Roy, M.; Binns, C.

    2013-09-01

    We have investigated atomic structure and magnetism in Fe nanoparticles with a diameter of 2 nm embedded in a Pd matrix. The samples for these studies were prepared directly from the gas phase by co-deposition, using a gas aggregation source and an MBE-type source for the Fe nanoparticles and Pd matrix respectively. Extended absorption fine structure (EXAFS) measurements indicate that there is an appreciable degree of alloying at the nanoparticle/matrix interface; at dilute nanoparticle concentrations, more than half of the Fe atoms are alloyed with Pd. This leads to a core/shell structure in the embedded nanoparticles, with an FexPd1-x shell surrounding a reduced pure Fe core. Magnetism in the nanocomposite samples was probed by means of magnetometry measurements, which were interpreted in the light of their atomic structure. These point to a magnetized cloud of Pd atoms surrounding the embedded nanoparticles which is significantly larger than around single Fe atoms in Pd. The coercivities in the Fe/Pd nanocomposite samples are larger than in FexPd1-x atomic alloys of corresponding composition, which is consistent with exchange coupling between the magnetically harder and softer regions in the nanocomposite samples.