Nanomaterials Characterization

Single and Mixed Phase TiO2 Powders by Excess Hydrolysis of Titanium Alkoxide

by Material Science

To investigate excess-hydrolysis of titanium alkoxides, TiO2 powders were fabricated from titanium-tetra-isopropoxide... more To investigate excess-hydrolysis of titanium alkoxides, TiO2 powders were fabricated from titanium-tetra-isopropoxide using 6:1 and 100:1 H2O:Ti (r) ratios. Powders were dried and fired at a range of temperatures (≤800ºC). Hydroxylation and organic content in powders were characterised using ATR-FTIR, laser Raman microspectroscopy, and elemental microanalysis; surface area and pore size distribution were evaluated using N2 gas adsorption; phase composition was analysed using XRD and laser Raman microspectroscopy; and crystallite size was evaluated by XRD, TEM and SEM. Results showed near-complete hydrolysis in a predominantly aqueous medium (r = 100), resulting in precipitated crystalline powders exhibiting brookite and anatase, which begin to transform to rutile below 500°C. Powders precipitated in a predominantly organic medium (r = 6) underwent partial hydrolysis, were highly porous and exhibited an amorphous structure, with crystallisation of anatase occurring at ~300°C and transformation to rutile beginning at 500°-600°C.

“The Story of the Samaritan and the Inn-Keeper (Luke 10:30-35): A Study in Character Rehabilitation,” Biblical Interpretation: A Journal of Contemporary Approaches 17 (2009): 422-47

by Bruce Longenecker

The aphorism 'context is everything' has been a guiding principle in many studies of Jesus' parabolic sayings. This is... more The aphorism 'context is everything' has been a guiding principle in many studies of Jesus' parabolic sayings. This is true, for instance, of studies attempting to recover a parable's significance in relation to the ministry of Jesus of Nazareth, or in relation to its literary placement and function, or in relation to its polyvalent potential. It is also true of this study, which examines Jesus' narrative of the Samaritan—usually referred to as the 'parable of the good Samaritan'. It suggests that, when the Samaritan story is placed within a certain contextual configuration, its narrative features align themselves in ways that have either been conspicuously neglected or consciously avoided in the history of the story's interpretation. Rather than neglecting or avoiding the significance of these narrative features, this essay seeks to exploit their interpretative significance in a fresh manner, entertaining possibilities of meaning beyond the Lukan interpretative framework. In particular, consideration is given to the relationship between the Samaritan and the innkeeper as representing an exceptional partnership that testifies to the reign of God in making each party vulnerable to loss while promoting goodness towards others.

High Density Growth of Indium seeded Silicon Nanowires in the Vapor phase of a High Boiling Point Solvent

by Hugh Geaney

Effect of Y3Al5O12 Nanoparticles on Efficiency of Double clad High Power Optical Fiber Laser with NLSE Characterization

by farshad akhtarian

Temperature dependent conductivity and structural properties of sol-gel prepared holmium doped Bi2O3 nanoceramic powder

by Prof.Dr. İbrahim USLU

İ. Taşçıoğlu, M. Arı, İ. Uslu, S. Koçyiğit, Y. Dağdemir, V. Çorumlu and Ş. Altındal
Ceramics International, CERI_5314
Accepted paper, Manuscript Number: CERI-D-12-00407R2

Holmium (Ho)-doped Bi2O3 nanoceramic powders derived from sol-gel method have been studied in terms of structural,... more Holmium (Ho)-doped Bi2O3 nanoceramic powders derived from sol-gel method have been studied in terms of structural, morphological, and electrical properties. The morphology of the nanoceramic materials was analyzed by scanning electron microscopy (SEM) and their structure by Xray powder diffraction (XRD). Temperature dependence of DC conductivity measurements of nanoceramic powders were carried out by using DC four-point probe technique (4PPT) in air at temperatures ranging from 429 °C to 896 °C (702-1169 K). Electrical conductivity results demonstrate that there is a sharp increase at around 700 °C, which indicates an existence of order-disorder transition. This result supported by the Differential Thermal Analyzer (DTA) curve and XRD pattern which show that the sample has stable high oxygen ionic conductivity fluorite type face centered cubic -phase. Electrical characteristics also show that the DC conductivity in the studied materials obeys Arrhenius relation with different activation energies and conduction mechanisms: two temperature regions with activation energies Ea1=1.40 eV (702-993 K) and Ea2=0.66 eV (1006-1169 K). The analysis of experimental data revealed that the translation motion of the charge carrier, oxygen vacancies, and space charge polarization are responsible for the change in activation energy as a function of temperature.

Facile Microwave-refluxing Synthesis and Catalytic Properties of Vanadium Pentoxide Nanomaterials.

by Homer Genuino

Qiu, Guohong, Dharmarathna, Saminda, Genuino, H., Zhang, Yashan, Huang, Hui, Suib, Steven L., 2011. Facile microwave-refluxing synthesis and catalytic properties of vanadium pentoxide nanomaterials. ACS Catalysis 1 (12) 1702-1709.

http://pubs.acs.org/doi/abs/10.1021/cs200437x?prevSearch=genuino&searchHistoryKey=

Enhancement of the photodegradation of N-Nitrosodimethylamine in water using amorphous and platinum manganese oxide catalysts.

by Homer Genuino

Genuino, Homer C., Njagi, Eric C., Benbow, Evan B., Hoag, George E., Collins, Joh B., Suib, Steven L., 2011. Enhancement of the photodegradation of N-nitrosodimethylamine in water using amorphous and platinum manganese oxide catalysts. Journal of Photochemistry and Photobiology A: Chemistry 217 (2-3) 284-292.

http://www.sciencedirect.com/science/article/pii/S1010603010004351

Size Controlled Growth of Germanium Nanorods and Nanowires by Solution Pyrolysis Directly on a Substrate

by Hugh Geaney

Optimization of open circuit voltage in amorphous silicon solar cells with mixed-phase (amorphous+nanocrystalline) p-type contacts of low nanocrystalline content

by Joshua Pearce

J. M. Pearce, N. Podraza, R. W. Collins, M.M. Al-Jassim, K.M. Jones, J. Deng, and C. R. Wronski "Optimization of Open-Circuit Voltage in Amorphous Silicon Solar Cells with Mixed Phase (Amorphous + Nanocrystalline) p-Type Contacts of Low Nanocrystalline Content", Journal of Applied Physics, 101(11), 114301, 2007.

Both the origins of the high open circuit voltages (VOC) in amorphous silicon solar cells having p layers prepared... more Both the origins of the high open circuit voltages (VOC) in amorphous silicon solar cells having p layers prepared with very high hydrogen dilution and the physical structure of these optimum p layers remain poorly understood topics, with several studies offering conflicting views. This work attempts to overcome the limitations of previous studies by combining insights available from electronic measurements, real time spectroscopic ellipsometry, atomic force microscopy, and both high-resolution transmission electron microscopy (TEM) and dark field TEM of cross sections of entire solar cells. It is found that solar cells fabricated with p layers having a low volume fraction of nanocrystals embedded in a protocrystalline Si:H matrix possess lower recombination at the i/p interface than standard cells and deliver a higher VOC. The growth of the p layers follows a thickness evolution in which pure protocrystalline character is observed at the interface to the i layer. However, a low density of nanocrystallites nucleates with increasing thickness. The advantages offered by the protocrystalline character associated with the amorphous phase of the mixed-phase (amorphous+nanocrystalline) p layers prepared with excess H2 dilution account for the improved VOC of the optimum p layers. In this model, the appearance of a low volume fraction of nanocrystals near the top transparent conductor interface is proposed to be incidental to the high VOC.

Improving Solar Water Disinfection SODIS with a Photoreactive TiO2 SWCNT Composite on Plastic PET Bottles

by Ravi Dinakar

For FREE full pdf visit:

http://www.jes2s.com/pdfs/Jan2012/Improving%20Solar%20Water%20Disinfection%20SODIS%20with%20a%20Photoreactive%20TiO2%20SWCNT%20Composite%20on%20Plastic%20PET%20Bottles.pdf

Authors:

Zizi Yu1,3*, Deborah Day2, and Shannon Ciston4
Student1, Teacher2: Amity Regional High School, 25 Newton Road, Woodbridge, CT 06525
Intern3, Mentor/Assistant Professor4: University of New Haven, West Haven, CT 06516
*Correspondence: zizi262@yahoo.com

Published in The Journal of Experimental Secondary Science (www.jes2s.com)

Approximately 1.1 billion people in the world lack access
to safe drinking water, an issue that causes two... more Approximately 1.1 billion people in the world lack access
to safe drinking water, an issue that causes two million
deaths a year due to waterborne diarrheal diseases. Solar
disinfection (SODIS), a point-of-use water treatment
method that uses UV radiation in sunlight to kill pathogenic
organisms, was discovered by Professor Aftim Acra in the
early 1980’s1. Because SODIS relies largely on weather
conditions, its efficiency varies greatly. The purpose of this
study was to improve SODIS by coating plastic PET bottles
with a TiO2 and a TiO2/SWCNT composite, a photocatalytic
nanomaterial that exhibits strong antibacterial activity.
Water samples were collected from the Quinnipiac River
in Wallingford, CT and transferred into the bottles to be
tested for bacteria at time intervals of 0 min., 180 min.,
and 360 min. of sun exposure. Two trials were performed
with the same bottles to test for bottle reusability, and
bacterial concentrations were determined through serial
dilutions and plate counting. Results show that the TiO2/
SWCNT composite coating was the most effective in
meeting EPA standards, preventing bacterial growth in
optimal temperatures, and producing strong coatings. The
TiO2/SWCNT composite coating did kill more bacteria as
hypothesized, but the full 360 min. of sun exposure was
required.

Combined in situ electrochemical impedance spectroscopy UV/Vis and AFM studies of Ag nanoparticle stability in perfluorinated films

by Benjamin Wilson

K. Yliniemi, a, b, B. Özkaya, b, N. Alissawi, c, V. Zaporojtchenko, c, T. Strunskus, c, B.P. Wilson, a,b,1, F. Faupel, c, G. Grundmeier, b

a Aalto University, Department of Chemistry, P.O. Box 16100, 00076 AALTO Espoo, Finland
b University of Paderborn, Institute for Polymer Materials and Processes, Faculty of Natural Science, Warburger Str. 100, 33098 Paderborn, Germany
c Institute for Materials Science, Multicomponent Materials, Faculty of Engineering, Christian-Albrechts University at Kiel, Kaiserstr. 2, 24143 Kiel, Germany

1 ASTUTE, College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP, UK.

Materials Chemistry and Physics Volume 134, Issue 1, 15 May 2012, Pages 302–308

In situ electrochemical UV/Vis spectroscopic analysis in combination with AFM measurements were performed to study the... more In situ electrochemical UV/Vis spectroscopic analysis in combination with AFM measurements were performed to study the reactivity of Ag nanoparticles sandwiched in between two polytetrafluorethylene (PTFE) films. The electrolyte uptake in the film was correlated with the onset of the changes in the surface plasmon resonance by measuring the film capacitance and the surface plasmon resonance peak simultaneously as a function of the exposure time. AFM studies indicate that both particle ripening and Ag dissolution take place and the dissolution kinetics was shown to decrease with increasing covering film thickness.

Synthesis and characterization of neodymium doped ceria nanocrystalline ceramic structures

by Prof.Dr. İbrahim USLU

Ceramics International
First Online March 2012
İbrahim Uslu, Arda Aytimur, Mustafa Kemal Öztürk, Serhat Koçyiğit

In this study, a new method to synthesize neodymium doped ceria ceramic nanopowders by the electrospinning of the... more In this study, a new method to synthesize neodymium doped ceria ceramic nanopowders by the electrospinning of the hybrid polymers solution of their composite precursor was put forward. Calcined and sintered nanopowders were characterized by FT-IR, XRD, BET, SEM, and AFM techniques. According to the XRD analysis, the obtained powders are single phase and independent of the dopant concentration in the range investigated. The crystallite sizes were calculated using Scherrer equation. Moreover, lattice parameters, dislocation densities and microstrain values were calculated. BET results show that the increase of the neodymium doped content decrease the surface area of the composite powders, confirming the highly ordered micro and mesostructure. SEM and AFM results show that the samples have spherical grains. According to the surface roughness measurements, the increase in the amount of neodymium and the decrease in the amount of cerium decreased the surface roughness.

Synthesis and Characterization of Dendrimer-Encapsulated Iron and Iron-Oxide Nanoparticles

by Ayse Demir

Co-authored with A. Baykal, M. S. Toprak, Z. Durmus, M. Senel, and H. Sozeri, original paper in 'JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM'

In this paper, a series of iron (Fe) containing nanoparticles were prepared by employing PAMAM (Poly(amidoamine),... more In this paper, a series of iron (Fe) containing nanoparticles were prepared by employing PAMAM (Poly(amidoamine), dendrimers with different generations (G0–G3) as templates and sodium borohydride as a reducing agent. The products have been characterized by TEM, FT-IR, XRD, VSM, TGA, and XPS. XRD analysis reveal low crystallinity of formed particles within the dendrimers, however, crystallinity of the nanoparticles was observed to increase with increasing generation of dendrimers. Dominant phases were determined as magnetite (Fe3O4 or maghemite, γ-Fe2O3). XPS analysis revealed the chemical composition of nanoparticles as iron oxide which indicated the oxidation of Fe species subsequent to the reduction process, in agreement with XRD analysis. The magnetization curves have superparamagnetic nonhysteretic characteristic at lower fields and with nonsaturation characteristic at high fields. Magnetic evaluation of samples with the 20:1 molar ratio of Fe:PAMAM showed decreasing superparamagnetic character and decreasing saturation magnetisation with increasing generation of dendrimers.

Characterization of Core Shell Cu-Au Nanoparticles by Microscopy Techniques

by Tianlong Wen

Silver-assisted colloidal synthesis of gold patchy particles with tunable patchiness

by Robin Klupp Taylor

Huixin Bao, Benjamin Butz, Zhou Zhou, Erdmann Spiecker, Martin Hartmann, Robin Klupp Taylor

Published in Langmuir - http://pubs.acs.org/doi/abs/10.1021/la204762z

Patchy particles possessing heterogeneous surface composition show great promise as self-organizing building blocks... more Patchy particles possessing heterogeneous surface composition show great promise as self-organizing building blocks for new classes of hierarchical functional structures. A major hurdle is the scalable synthesis of stable patches on nanosized core particles with arbitrarily defined patch number and coverage. So far, few methods have been reported which could be expected to meet these challenges. Recently we described the heterogeneous nucleation and growth of silver patches on silica nanospheres via a template free colloidal route. The patches produced, although tunable in size and number and showing interesting plasmon resonant properties, were rather unstable and degraded rapidly during attempts to process them further. In the present work, therefore, we set out to explore if related approaches can be employed to produce patchy particles involving gold, which is known to be more stable. The differences between typical patch precursors Ag+ and [AuClx(OH)4-x]- and their respective interactions with amorphous silica make this a significant challenge. We show that preformed small silver patches in addition to the presence of a reducing agent are necessary for the formation of gold patches conformal to the silica nanosphere surface. Systematic study of the process parameters and their influence on the patchiness as well as in-depth analytical TEM investigation of the patch composition reveal that patches spread over the silica surface via a cycle of galvanic dissolution and redeposition of silver.The resulting gold patchy particles remain stable during subsequent storage or washing and display tunable plasmon resonances within the visible and near-IR spectrum.

Synthesis and characterization of boron-doped Bi 2 O 3-La 2 O 3 fiber derived nanocomposite precursor

by Arda Aytimur

Şenol Durmuşoğlu, İbrahim Uslu, Tuncay Tunç, Selda Keskin, Arda Aytimur and Ahmet Akdemir

JOURNAL OF POLYMER RESEARCH
Volume 18, Number 6, 1999-2004, DOI: 10.1007/s10965-011-9607-5

Boron doped poly(vinyl) alcohol/ bismuth - lanthanum acetate (PVA/Bi-La) nanofibers were prepared by electrospinning... more Boron doped poly(vinyl) alcohol/ bismuth - lanthanum acetate (PVA/Bi-La) nanofibers were prepared by electrospinning using PVA as a precursor. The effect of boron doping was investigated in terms of solution properties, morphological changes and thermal characteristics. The fibers were characterized by FT-IR, XRD, SEM and BET. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. XRD analyses showed that boron doping increased the peak intensities and indicated that the boron doping enhanced the crystallite size. Moreover, no shifts were noticed in diffraction angles for boron doped and undoped samples. Therefore, boron doping did not significantly alter the lattice spacing. The SEM micrograph of the fibers showed that the addition of boron resulted in the formation of cross linked bright surfaced fibers. Also, grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 170 nm and 120 nm respectively. The BET results show that boron undoped and doped Bi2O3-La2O3 nanocrystalline powder ceramic structures sintered at 800 °C have surface areas of 20.44 m2/g and 12.93 m2/g, respectively.

Electronic structures and adsorption configurations of gold nanoclusters on cerium oxide defect surfaces

by Neil Lawrence

co-authored with Lu Wang, Wai-Ning Mei, Neil Lawrence, Joseph R. Brewer, James Wells-Kingsbury, Marcella Ihrig,  Chin Li Cheung, and Yun-Liang Soo

Proceedings

Fluorite-structured cerium oxide (or ceria, CeO_2-x, 0 ≤ x ≤ 0.5) has been shown to be an... more Fluorite-structured cerium oxide (or ceria, CeO_2-x, 0 ≤ x ≤ 0.5) has been shown to be an important material in catalysis, yet few study have investigated the efect of non-dopant introduced oxygen vacancy defect (OVD). In addition, we found experimentally that when doped with Au nanoclusters, the catalytic ability of ceria was enhanced. In this work, we modeled and optimized an (111) fluorite-structured slab model of highly defective ceria with a chemical formula corresponding to CeO_1.5. The optimized surface structure of this model was found to contain both surface and sub-surface OVDs, similar to those observed in our HRTEM data for low pressure activated nanoceria.
Signicantly, the model captures comparable reduction in the average Ce-O bond distance and also atomic coordination numbers observed in our EXAFS data. To explore the roles of Au nanoclusters, we adsorbed flat clusters of 3, 4, 9, 10, and 19 Au atoms on ceria slabs, optimized their configurations, and computed the corresponding electronic structures applying 1st principles approach. Consequently, we present the density of states results to elucidate the experimentally observed optical property changes and s-d hybridization.

Production and characterization of poly(vinyl alcohol)/poly(vinylpyrrolidone) iodine/poly(ethylene glycol) electrospun fibers with (hydroxypropyl)methyl cellulose and aloe vera as promising material for wound dressing

by Arda Aytimur

İbrahim Uslu, Arda Aytimur

Journal of Applied Polymer Science
Article first published online: 21 NOV 2011
DOI: 10.1002/app.35525

Biocompatible poly(vinyl alcohol)/poly (vinylpyrrolidone) iodine/poly(ethylene glycol) fibers containing... more Biocompatible poly(vinyl alcohol)/poly (vinylpyrrolidone) iodine/poly(ethylene glycol) fibers containing (hydroxypropyl)methyl cellulose (HPMC) and aloe vera were successfully prepared by electrospinning their aqueous solution. Aloe vera which is known to be effective in the treatment of various wounds was added to the polymer solution. HPMC was added to the system as the water retention agent. The hybrid fiber mats were subjected to detailed analysis using a differential scanning calorimeter, a scanning electron microscope (SEM), and a Fourier transform infrared spectrometer. Images obtained from the SEM showed that the polymer fibers were linear, homogenous, and contained no beading. The fiber diameters ranged between 100 and 900 nm. It was seen that the electrospun mats obtained could potentially be used as a material for dressing wounds.

Magnesia Stabilized Zirconia Doped with Boron, Ceria and Gadolinia

by Arda Aytimur

Article in press, available online 20 January 2012

In this study, magnesia stabilized zirconia based nanocrystalline ceramics were produced through a polymer precursor... more In this study, magnesia stabilized zirconia based nanocrystalline ceramics were produced through a polymer precursor route using gadolinium and boron. The powders were characterized during the various steps by structural and morphological techniques (FT-IR, XRD, and SEM). XRD results proved that a tetragonal phase is predominant for all samples with varying magnesium contents and no monoclinic zirconia solid solution appears. The crystallite sizes of the samples were calculated using Scherrer equation. The smallest crystallite size was obtained for the sample containing Zr/Mg/Ce/Gd/B ratio of 82/0/10/8/0. The lattice parameters were calculated for cubic, tetragonal, hexagonal, and orthorhombic structures. SEM results show all the samples have spherical grains. The average grain diameters were calculated for all the samples. The smallest average grain diameter was obtained for the sample containing Zr/Mg/Ce/Gd/B ratio of 82/0/10/8/0.

Characterization of Mg doped ZnO Nanocrystallites prepared via electrospinning

by Arda Aytimur

Ceramics International
Manuscript Number: CERI-D-11-01236R2
Saime Sebnem Cetin, Ibrahim Uslu, Arda Aytimur, Suleyman Ozcelik
Accepted for publication

Undoped and Mg doped ZnO nanofibers with different doping concentrations were successfully synthesized using the... more Undoped and Mg doped ZnO nanofibers with different doping concentrations were successfully synthesized using the electrospinning technique. The nanofiber structures were calcined at 300 oC, 400 oC, 500 oC, and 600 oC respectively. It was observed that the nanofibers turned into a nanoparticular structure at the calcining temperature of 400 oC. The nanoceramic mats were characterized by the Fourier transform infrared-attenuated total reflectance spectroscopy and by the scanning electron microscopy. The electronic band transitions of as-deposited and calcined films were identified by the evaluation of the photoluminescence measurements at room temperature. It was observed that the exitonic transition energy of the ZnO nanostructure blue-shifted to a high energy value with an increasing Mg doping ratio. In order to estimate the decomposition temperature of the nanofibers turning into a nanoparticular structure, the nanofiber structure was calcined at temperatures between 300 oC and 400 oC, the temperature ramp being 20 oC. The evaluation of the emission spectra of the calcined structures show that the decomposition of electrospun nanofibers started at 320 oC. In addition, band gap energies of the samples were determined by the transmittance measurement of the samples and by the UV-VIS spectrophotometer at the room temperature.