ISRN Nanotechnology

Potentiostatic Deposition and Characterization of Cuprous Oxide Thin Films

A. El-Shaer and A. R. Abdelwahed — Wed, 17 Apr 2013 16:34:17 +0000

Electrodeposition technique was employed to deposit cuprous oxide Cu2O thin films. In this work, Cu2O thin films have been grown on fluorine doped tin oxide (FTO) transparent conducting glass as a substrate by potentiostatic deposition of cupric acetate. The effect of deposition time on the morphologies, crystalline, and optical quality of Cu2O thin films was investigated.

Preparation of Gd Complex-Immobilized Silica Particles and Their Application to MRI

Wed, 10 Apr 2013 12:02:22 +0000

A preparation method for Gd-ethylenediaminetetraacetic acid disodium salt dihydrate (ETDA) complex-immobilized silica particles (Gd-EDTA/SiO2) is proposed. Preparation of spherical silica particles was performed by a sol-gel method at 35°C using 0.2 M tetraethylorthosilicate, 25 M H2O, and 0.01 M NaOH in ethanol, which produced silica particles with an average size of nm. Immobilization of Gd-EDTA on the silica particles was conducted at 35°C by introducing amino groups on the silica particles with (3-aminopropyl)trimethoxysilane at pH 3 (NH2/SiO2) and then making Gd-EDTA act on the NH2/SiO2 particles at pH 5. The as-prepared Gd-EDTA/SiO2 particle colloid solution was concentrated up to a Gd concentration of 0.347 mM by centrifugation. The sphere structure of Gd-EDTA/SiO2 particles was undamaged, and the colloid solution was still colloidally stable, even after the concentrating process. The concentrated Gd-EDTA/SiO2 colloid solution revealed good MRI properties. A relaxivity value for T1-weighted imaging was as high as 5.15 mM−1 s−1, that was comparable to that for a commercial Gd complex contrast agent.

A Quick Process for Synthesis of ZnO Nanoparticles with the Aid of Microwave Irradiation

Tran Thi Ha, Ta Dinh Canh, and Nguyen Viet Tuyen — Wed, 03 Apr 2013 13:36:35 +0000

Reaction between sodium hydroxide and zinc acetate leads to the formation of zinc hydroxide, Zn(OH)2. The as-prepared Zn(OH)2 was then decomposed by using conventional heating process or with the aid of microwave irradiation. The nanoproducts of both methods were ZnO nanostructures of different size and shape, but the microwave irradiation method shows many advantages in yield and reaction time. Some surfactants such as SDS, CTAB, or PVP were then used to cap the product for studying the influence on the morphology and properties of the nanostructures.

Evaluation of the X-Ray Absorption by Gold Nanoparticles Solutions

R. Künzel, E. Okuno, R. S. Levenhagen, and N. K. Umisedo — Mon, 11 Mar 2013 11:19:31 +0000

The increase in the X-ray absorption due to gold nanoparticles was investigated by using aqueous solutions containing gold (Au) nanoparticles. A sample with 15 nm in size nanoparticles and 0.5 mg/mL gold concentration and a distilled water sample were used. Transmitted X-ray beams through the samples were registered with a CdTe detector and with an ionization chamber. Results show an enhancement in the X-ray absorption in the range 20%–6% for beams generated from 20 kV to 120 kV tube voltages, respectively. Results show that the use of gold nanoparticles, even at low concentrations, should result in a significant contrast enhancement for low-energy X-ray beams.

Ordered Porous Nanomaterials: The Merit of Small

Ángel Berenguer Murcia — Tue, 26 Feb 2013 18:56:13 +0000

This paper will introduce the reader to some of the “classical” and “new” families of ordered porous materials which have arisen throughout the past decades and/or years. From what is perhaps the best-known family of zeolites, which even now to this day is under constant research, to the exciting new family of hierarchical porous materials, the number of strategies, structures, porous textures, and potential applications grows with every passing day. We will attempt to put these new families into perspective from a synthetic and applied point of view in order to give the reader as broad a perspective as possible into these exciting materials.

In Situ Real-Time TEM Reveals Growth, Transformation and Function in One-Dimensional Nanoscale Materials: From a Nanotechnology Perspective

Nikolay Petkov — Sun, 27 Jan 2013 11:03:11 +0000

This paper summarises recent developments in in situ TEM instrumentation and operation conditions. The focus of the discussion is on demonstrating how improved understanding of fundamental physical phenomena associated with nanowire or nanotube materials, revealed by following transformations in real time and high resolution, can assist the engineering of emerging electronic and optoelectronic devices. Special attention is given to Si, Ge, and compound semiconductor nanowires and carbon nanotubes (CNTs) as one of the most promising building blocks for devices inspired by nanotechnology.

Raman Spectroscopy in Graphene-Based Systems: Prototypes for Nanoscience and Nanometrology

Ado Jorio — Thu, 06 Dec 2012 15:26:14 +0000

Raman spectroscopy is a powerful tool to characterize the different types of sp2 carbon nanostructures, including two-dimensional graphene, one-dimensional nanotubes, and the effect of disorder in their structures. This work discusses why sp2 nanocarbons can be considered as prototype materials for the development of nanoscience and nanometrology. The sp2 nanocarbon structures are quickly introduced, followed by a discussion on how this field evolved in the past decades. In sequence, their rather rich Raman spectra composed of many peaks induced by single- and multiple-resonance effects are introduced. The properties of the main Raman peaks are then described, including their dependence on both materials structure and external factors, like temperature, pressure, doping, and environmental effects. Recent applications that are pushing the technique limits, such as multitechnique approach and in situ nanomanipulation, are highlighted, ending with some challenges for new developments in this field.

Strategies for Fabricating Nanogap Single-Crystal Organic Transistors

S. Alborghetti, P. Stamenov, G. Fois, and J. M. D. Coey — Sun, 25 Nov 2012 09:11:05 +0000

Nanotechnology is an emerging technology for fabricating nanostructures where at least one dimension is smaller than 100 nm. This paper explains how single-crystal organic transistors of channel length down to just 7 nm can be fabricated without damaging the organic material. Single crystals of C60, rubrene, and pentacene have been chosen in our structures, but the same process can be used for a wide variety of organics. The method combines high-resolution electron-beam lithography and vacuum device assembly with piezo manipulators. As modern devices are typically designed with short semiconducting channel length, this type of fabrication methods allows downscaling of organic electronic devices for research purposes.

Evaluation of Viability and Proliferation Profiles on Macrophages Treated with Silica Nanoparticles In Vitro via Plate-Based, Flow Cytometry, and Coulter Counter Assays

S. Bancos, D.-H. Tsai, V. Hackley, J. L. Weaver, and K. M. Tyner — Wed, 14 Nov 2012 10:57:02 +0000

Nanoparticles (NPs) are known to interfere with many high-throughput cell viability and cell proliferation assays, which complicates the assessment of their potential toxic effects. The aim of this study was to compare viability and proliferation results for colloidal silica (SiO2 NP; 7 nm) in the RAW 264.7 mouse macrophage cell line using three different techniques: plate-based assays, flow cytometry analysis, and Coulter counter assays. Our data indicate that CellTiter-Blue, XTT, and CyQuant plate-based assays show increased values over control at low SiO2 NPs concentrations (0.001–0.01 g/L). SiO2 NPs show little-to-no interference with flow cytometry and Coulter counter assays, which not only were more reliable in determining cell viability and proliferation at low concentrations in vitro, but also identified changes in cell granularity and size that were not captured by the plate-based assays. At high SiO2 NP concentrations (1 g/L) all techniques indicated cytotoxicity. In conclusion, flow cytometry and Coulter counter identified new cellular features, and flow cytometry offered more flexibility in analyzing the viability and proliferation profile of SiO2 NP-treated RAW 264.7 cells.

Gold-Nanoparticle Decorated Graphene-Nanostructured Polyaniline Nanocomposite-Based Bienzymatic Platform for Cholesterol Sensing

Deepshikha Saini, Ruchika Chauhan, Pratima R. Solanki, and T. Basu — Wed, 14 Nov 2012 09:42:53 +0000

A novel nanobiocomposite bienzymatic amperometric cholesterol biosensor, coupled with cholesterol oxidase (ChOx) and horseradish peroxidase (HRP), was developed based on the gold-nanoparticle decorated graphene-nanostructured polyaniline nanocomposite (NSPANI-AuNP-GR) film which was electrochemically deposited onto indium-tin-oxide (ITO) electrode from the nanocomposite (NSPANI-AuNP-GR) dispersion, as synthesized by in situ polymerization technique. The gold nanoparticle-decorated graphene-nanostructured polyaniline nanocomposite (NSPANI-AuNP-GR) offers an efficient electron transfer between underlining electrode and enzyme active center. The bienzymatic nanocomposite bioelectrodes ChOx-HRP/NSPANI-AuNP-GR/ITO have exhibited higher sensitivity, linearity, and lower value than monoenzymatic bioelectrode (ChOx/NSPANI-AuNP-GR/ITO). It is inferred that bienzyme-based nanobioelectrodes offer wider linearity (35 to 500 mg/dL), higher sensitivity (0.42 μAmM−1), low km value of 0.01 mM and higher accuracy for testing of blood serum samples than monoenzyme system. Mechanism of the overall biochemical reaction has been proposed to illustrate the enhanced biosensing performance of the bienzyme system. The novelty of the electrode lies on reusability, extended shelf life, and accuracy of testing blood serum samples.

Encapsulation of Berberine in Nano-Sized PLGA Synthesized by Emulsification Method

Manisha Khemani, Maheshwar Sharon, and Madhuri Sharon — Mon, 17 Sep 2012 14:55:52 +0000

Nanoparticles of PLGA (polylactide glycolic acid) were prepared using biodegradable poly (D, L-lactide-co-glycolide)—75 : 25, by emulsification method using PVA (Mol. Wt. 9000) or didodecyl dimethyl ammonium bromide (DMAB) as surfactant. Nanoparticles were morphologically characterized using scanning electron microscope (SEM) and particle size analyzer. The distribution of size of PLGA nanoparticles was in the range of 48–211 nm. Berberine, a yellow isoquinoline alkaloid that is used as traditional anticancer drug, was loaded on to PLGA nanoparticles by single emulsion as well as multiple emulsion solvent evaporation techniques. Particle size analysis showed an increase in berberine loaded PLGA NP size to 180–310 nm when PVA was used as a stabilizer. Whereas use of DMAB as a stabilizer led to precipitation. In vitro drug release analysis revealed that acidic pH of 5.5 was more suitable for release of berberine than pH 7.4.

Development of Quantum Simulator for Emerging Nanoelectronics Devices

Dinh Sy Hien — Tue, 28 Aug 2012 15:48:54 +0000

We have developed NEMO-VN2, a new quantum device modeling tool that simulates a wide variety of quantum devices including the resonant tunneling diode, the single electron transistor, the molecular field effect transistor, the carbon nanotube field effect transistor, and the spin field effect transistor. In this work the nonequilibrium Green’s function is used to perform a comprehensive study of the emerging nanoelectronics devices. The program has been written by using graphic user interface of Matlab. NEMO-VN2 uses Matlab to solve Schrodinger equation to get current-voltage characteristics of quantum devices. In the paper, we present a short overview of the theoretical methodology using non-equilibrium Green’s function for modeling of various quantum devices and typical simulations used to illustrate the capabilities of the NEMO-VN2.

Properties of PbS: Ni2+ Nanocrystals in Thin Films by Chemical Bath Deposition

Thu, 16 Aug 2012 16:24:56 +0000

The growth of nanocrystalline PbS films by chemical bath deposition (CBD) onto glass at temperature 𝑇=20±2∘C is presented in this research. We report on the modification of structural, optical, and electrical nanostructures due to in situ Ni-doping. The morphological changes of the layers were analyzed using SEM, AFM, and TEM. XRD spectra displayed peaks at 2θ = [26.00, 30.07, 43.10, 51.00, 53.48], indicating growth on the zinc blende face. The grain size determined by X-rays diffraction of the undoped samples was ∼36 nm, whereas with the doped sample was 3.2–5 nm. By TEM, the doped PbS was found crystalline films in the range 3.5–5 nm. Optical absorption (OA), and forbidden bandgap energy (𝐸𝑔) shift disclose a shift in the range 2.1–3.8 eV. Likewise, the dependence of 𝐸𝑔 with the radius size and interplanar distance of the lattice is discussed. Raman spectroscopy (RS) exhibited an absorption band ∼135 cm−1 displaying only a PbS ZB structure. The thermal energy for the films was determined from the slope of dark conductivity (DC) and the energy was estimated to be 0.15 to 0.5 eV.

An Approach to Tentative Reference Levels Setting for Nanoparticles in the Workroom Air Based on Comparing Their Toxicity with That of Their Micrometric Counterparts: A Case Study of Iron Oxide Fe3O4

Tue, 07 Aug 2012 13:51:35 +0000

We overview the state of the art in the field of safe exposure levels setting for nanomaterials together with the previously published results of our experimental investigations characterizing comparative toxicity of the iron oxide Fe3O4 (magnetite) in the form of microparticles and nanoparticles of different size and comparative activity of the defensive alveolar phagocytosis response to their pulmonary deposition. An approach to the substantiation of acceptable workplace exposure limits of metallic nanoparticles is discussed and, specifically, the tentative reference level for magnetite nanoparticles is recommended.

Enhancement of Resistance Switching in Electrodeposited Co-ZnO Films

Dewei Chu, Adnan Younis, and Sean Li — Tue, 31 Jul 2012 11:49:11 +0000

High quality Co-doped ZnO films were prepared with electrodeposition. The correlation among the surface morphology, lattice structure, Co-dopant distribution, and resistance switching properties of the as-deposited films were investigated. It is found that resistance switching behaviour could be manipulated by controlling the composition of Co in the ZnO films. The significant enhancement of resistance switching was achieved with 5 at% Co doping in the films, and the possible switching mechanism was also discussed.

Spray Pyrolysis Deposition of Nanostructured Tin Oxide Thin Films

G. E. Patil, D. D. Kajale, V. B. Gaikwad, and G. H. Jain — Tue, 31 Jul 2012 10:56:39 +0000

Nanostructured SnO2 thin films were grown by the chemical spray pyrolysis (CSP) method. Homemade spray pyrolysis technique is employed to prepare thin films. SnO2 is wide bandgap semiconductor material whose film is deposited on glass substrate using aqueous solution of SnCl4⋅5H2O as a precursor. XRD (X-ray diffraction), UV (ultraviolet visible spectroscopy), FESEM (field emission scanning electron microscopy), and EDS (energy dispersive spectroscopy) analysis are done for structural, optical, surface morphological, and compositional analysis. XRD analysis shows polycrystalline nature of samples with pure phase formation. Crystallite size calculated from diffraction peaks is 29.92 nm showing nanostructured thin films. FESEM analysis shows that SnO2 thin film contains voids with nanoparticles. EDS analysis confirms the composition of deposited thin film on glass substrate. UV-visible absorption spectra show that the bandgap of SnO2 thin film is 3.54 eV. Bandgap of SnO2 thin film can be tuned that it can be used in optical devices.

Nanosilver Application in Dental Cements

Mon, 30 Jul 2012 08:41:44 +0000

Streptococcus mutans is the microorganism mostly responsible for initiation of tooth decay and also for the progression of an established lesion. Silver has been used for its antibacterial properties for many years, in different forms: ionised and elementary forms, as silver zeolites or as nanoparticles. The purpose of this study was to evaluate the antibacterial activity of three dental cements modified by nanosilver. Three cements were used: Sealapex, RelyX ARC, and Vitrebond. The cements were incorporated with 0.05 mL of silver nanoparticles solution. Control groups were prepared without silver. Six Petri plates with BHI were inoculated with S. mutans using sterile swabs. Three cavities were made in each agar plate (total = 18) and filled with the manipulated cements. They were incubated at 37∘C for 48 h, and the inhibition halos were measured. The paired t-Test was used for statistical analysis (𝑃<0.05). No inhibition halos were obtained for Sealapex and Rely X, but Vitrebond showed bactericidal activity without silver and enhanced effect with silver incorporation.

Chemotherapy of Prostate Cancer by Targeted Nanoparticles Trackable by Magnetic Resonance Imaging

Mohamed O. Abdalla, Timothy Turner, and Clayton Yates — Tue, 24 Jul 2012 13:13:19 +0000

Prostate cancer (CaP) is the commonest diagnosed malignancy and the second main cause of cancer mortality in males in the United States. Thus, there is an urgent need to develop novel drug delivery systems to improve the chemotherapy option for CaP patients. The goal of this paper is to describe novel moleculary guided nanoscale drug delivery system with dual functionality for treatment and MR imaging of CaP. We describe the synthesis of iron oxide nanoparticles (IONPs) which are then coated with carboxyl-ended amphiphilic polymer. We present the protocol for tethering of the CaP targeting protein, human amino terminal fragment (hATF) to the terminal carboxyls of the IONPs. We describe the drug loading and release and the methods for measuring of the internalization of the hATF-guided IONPs into CaP cells. We also describe the methods for usages of IONPs are MR imaging contrast agent and successful targeted drug carriers.

Monte Carlo Study of Magnetism of the Fe/Gd Multilayers: Dependence on the Layers Thickness and Interface Morphology

Abdelati Razouk, Mohamed Sahlaoui, and Mohamed Sajieddine — Tue, 10 Jul 2012 10:32:48 +0000

We present the results of the Monte Carlo simulations of Fe/Gd multilayers and a comparison of the models studied with experimental results. The Heisenberg model interactions are considered for both ferromagnetic and antiferromagnetic cases. At thermal equilibrium magnetization, the Curie temperature is investigated for different thicknesses of Fe layers and interface morphology in Fe/Gd multilayers. It turns out that the magnetic properties of the Fe/Gd multilayers strongly depend on magnetization amplitude with interface composition, the spatial arrangement of magnetic atoms, and the thickness of Fe layers.

Assessment of Toxicity of Cdse/Cds/Zns/S,S-Dihydrolipoic Acid/Polyacrylic Acid Quantum Dots at Danio rerio Embryos and Larvae

Mon, 09 Jul 2012 09:33:56 +0000

Quantum dots (QDs) are nanosized semiconductor crystals. They are currently applied in different science fields such as medicine, namely, cancer diagnostics and treatment. QD toxicity is caused by the toxicity of their components. In vivo application of QDs requires their toxicity assessment, so the purpose of this work has been the estimation of acute and chronic toxicity of the QDs at Danio rerio embryos and larvae, QDs being composed of CdSe/CdS/ZnS/S,S-dihydrolipoic acid/polyacrylic acid. We have found no QD acute toxicity during 48 hours of QDs action at the embryo up to the concentration of 185 μM Cd. QDs have been found to be toxic only at 5–7 days of action, it shows that QDs act accumulatively. Beside lethality, we have observed different larval development defects, that is, differently localized edemas, lag of development, tail curvature, and swimming bladder malformation. Our experimental data as well as literature data show that toxicity of the quantum dots at Danio rerio embryos and larvae is primarily caused by toxic action of Cd2+ ion which arises from partial dissociation of CdSe and CdS molecules.

Nanocrystalline Nd-Fe-B Alloys for Polymer-Bonded Magnets Production

Sun, 08 Jul 2012 14:06:26 +0000

This study presents how different nanostructures of starting Nd-Fe-B particles have influence on magnetic properties of polymer-bonded Nd-Fe-B materials. Two types of nanocrystalline Nd-Fe-B alloys were used for polymer composite production by compression molding technique. The particles with low neodymium content (Nd-low) have nanocomposite structure with small exchange coupling effect between hard and soft magnetic phase. In other hand, practically monophase hard magnetic structure of Nd-Fe-B particles with stoichiometric neodymium content (Nd-stoich) shows improved magnetic properties. With increasing concentration of polymer matrix, the coercivity (Hcb), remanence (Br), and maximum energy product ((BH)max) decrease more prominenty for composites with stoichiometric Nd-Fe-B content.

TiO2 Transparent Thin Film for Eliminating Toluene

Thu, 05 Jul 2012 09:55:59 +0000

TiO2 nanoparticles undergo a single-phase transition: from amorphous to anatase when calcined at 450°C. It can be noticed from the XRD and AFM results that the particle size of TiO2 is below 30 nm. Results from viscometer and UV-Vis analysis showed that the film thickness is closely related to the viscosity of dip-coating solutions. It was found that the contact angle for water decreased after being illuminated with UV light at certain periods of time. This indicates that these films exhibit hydrophilic properties that can be used on self-cleaning surfaces and antifogging mirrors. Heterogeneous photocatalytic oxidation allows the oxidation of airborne volatile organic compounds (VOCs) into carbon dioxide and water in the presence of a semiconductor catalyst and UV light source. Titanium dioxide, due to its chemical stability, nontoxicity, and low cost, represents one of the most efficient photocatalysts. Photocatalytic activity of the TiO2 thin films was evaluated by using toluene and results showed that this film is successful in decomposing toluene.

An Overview on Nanocrystalline ZnFe2O4, MnFe2O4, and CoFe2O4 Synthesized by a Thermal Treatment Method

Mahmoud Goodarz Naseri, Elias B. Saion, and Ahmad Kamali — Thu, 05 Jul 2012 09:53:28 +0000

This study reports the simple synthesis of MFe2O4 (where M=Zn, Mn, and Co) nanoparticles by a thermal treatment method, followed by calcination at various temperatures from 723 to 873 K. Poly(vinyl pyrrolidone) (PVP) was used as a capping agent to stabilize the particles and prevent them from agglomeration. The characterization studies were conducted by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle sizes were obtained by TEM images, which were in good agreement with the XRD results. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands for all the calcined samples. Magnetic properties were demonstrated by a vibrating sample magnetometer (VSM), which displayed that the calcined samples exhibited superparamagnetic and ferromagnetic behaviors.

Encapsulation of Silver Nanoparticles in a Polystyrene Matrix by Miniemulsion Polymerization and Its Antimicrobial Activity

Wed, 27 Jun 2012 10:08:05 +0000

Surface-modified silver nanoparticles (NAg) were encapsulated into a polystyrene (PS) matrix by in situ miniemulsion polymerization. Silver nanoparticles were modified with 3-aminopropyltrimethoxysilane (APTMS) that acts as a coupling agent and costabilizer in the polymerization reaction. The PS-Nag nanocomposites synthesized via miniemulsion polymerization were made at two different concentrations of the initiator (0.7 and 2.5 g/L in H2O); at higher concentration of the initiator the conversion and efficiency of encapsulation increases, and the average particle size decreases. The PS-NAg composites showed excellent antimicrobial performance toward bacteria such as Escherichia coli and Staphylococcus aureus.

Preparation, Characterization, and H2S Sensing Performance of Sprayed Nanostructured SnO2 Thin Films

Tue, 26 Jun 2012 15:24:16 +0000

Nanostructured SnO2 thin films were prepared by spraying tin chloride dihydrate onto the heated glass substrate at 250°C. The films were fired at 500°C. As-prepared thin films were studied using XRD and FESEM to know crystal structure and surface morphology. The average crystallite and grain size observed from XRD and FF-SEM was found to be less than 33 and 67 nm, respectively. The films sprayed for 30 min were observed to be most sensitive to H2S at 250°C. The results are discussed and interpreted.

The Separation Power of Nanotubes in Membranes: A Review

Bart Van der Bruggen — Mon, 11 Jun 2012 11:41:59 +0000

Research on mixed matrix membranes in which nanoparticles are used to enhance the membrane's performance in terms of flux, separation, and fouling resistance has boomed in the last years. This review probes on the specific features and benefits of one specific type of nanoparticles with a well-defined cylindrical structure, known as nanotubes. Nanotube structures for potential use in membranes are reviewed. These comprise mainly single-wall carbon nanotubes (SWCNTs) and multiwall carbon nanotubes (MWCNTs), but also other structures and materials, which are less studied for membrane applications, can be used. Important issues related to polymer-nanotube interactions such as dispersion and alignment are outlined, and a categorization is made of the resultant membranes. Applications are reviewed in four different areas, that is, gas separation, water filtration, drug delivery, and fuel cells.

Luminescence Properties of Eu- and Mg-Codoped Sol-Gel SiO2 Glasses

Martin O. Onani, Paul Mushonga, Lehlohonolo F. Koao, and Francis B. Dejene — Tue, 05 Jun 2012 08:25:28 +0000

A series of SiO2 nanostructures codoped with Eu3+; Mg2+ ions were obtained by a sol-gel method. The gels synthesized by the hydrolysis of Si(OC2H5)4, Eu(NO3)3·6H2O, and Mg(NO3)2 were heated in air at 600°C for 2 hours. Firstly, the total amount of Eu3+ ions was varied from 0 to 2.0 mol% to investigate the effect of self-damping, while in the second case, the Eu3+ ions were kept constant in the experiment at 0.5 mol% total doping and Mg2+ ions varied. The samples were characterized by X-ray diffraction, TEM, EDS, and UV lamp-excited luminescence spectroscopy. The Eu3+ ions were homogeneously dispersed in the silica and interacting with the small (1–5 nm) amorphous silica matrix. Strong red emissions located at 614 nm and 590 nm for doped and codoped SiO2 were observed from the UV light excitation at room temperature. The composition of around 1.25 mol% Eu3+ gave highest emission intensity. SiO2; Mg2+ ions portray strongly enhanced emissions due to energy transfer from Mg2+ to Eu3+, which is due to radiative recombination. An increase in luminescence intensity was observed as the Mg2+-to-Eu3+ ratio increased for the range investigated. The results show Eu3+ ion is located inside or at the surface of disordered SiO2 nanoparticles.

Synthesis, Characterization, and Spectroscopic Properties of ZnO Nanoparticles

Satyanarayana Talam, Srinivasa Rao Karumuri, and Nagarjuna Gunnam — Tue, 22 May 2012 10:28:47 +0000

ZnO nanoparticles have been synthesized by precipitation method from Zinc nitrate. The powder was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected-area electron diffraction, UV-vis optical absorption, and photoluminescence spectroscopy analyses. XRD patterns showed that ZnO nanoparticles have hexagonal unit cell structure. SEM and TEM pictures reveal the morphology and particle size of prepared ZnO nanoparticles. The UV-vis absorption spectrum shows an absorption band at 355 nm due to ZnO nanoparticles. The photoluminescence spectrum exhibits two emission peaks one at 392 nm corresponding to band gap excitonic emission and another located at 520 nm due to the presence of singly ionized oxygen vacancies. The synthesis method has potential for application in manufacturing units due to ease processing and more economical reagents.

High-Purity Nanopowders for Laser Applications

Deepak Ganta, Ganesh Venugopal, Andrew T. Hunt, and Michael Sapp — Wed, 16 May 2012 11:44:40 +0000

We have successfully developed high-quality laser-grade yttrium aluminum garnet (YAG), and lutetium oxide (Lu2O3), using a novel combustion chemical vapor condensation (CCVC) technique based on a proprietary NanoSpray Combustion process. The purity of the nanopowders was >99%. Nanopowders with different dopants have been synthesized over a 10–200 nm size range, with low-cost, high-purity precursors that are viable for large-scale production. Great strides have also been made in developing highly dense (>99% theoretical density) polycrystalline Nd-doped YAG pellets using vacuum sintering and hot isostatic pressing (HIP). This method is an alternative to the Czochralski method for making single-crystal ceramic bodies, which has several disadvantages including high cost, size, shape restrictions, and limitations in Nd concentrations (∼1 at %). Nanomaterials also enable higher percentages of Nd to be incorporated into the YAG lattice which improves laser efficiency and >85% near IR transmission, thereby reducing scattering losses associated with larger grain-size polycrystalline materials.

A CNTFET-Based Nanowired Induction Two-Way Transducers

Rostyslav Sklyar — Mon, 14 May 2012 09:06:30 +0000

A complex of the induction magnetic field two-way nanotransducers of the different physical values for both the external and implantable interfaces in a wide range of arrays are summarized. Implementation of the nanowires allows reliable transducing of the biosignals' partials and bringing of carbon nanotubes into circuits leading to examination of the superconducting transition. Novel sensors are based on the induction magnetic field principle, which causes their interaction with an ambient EM field. Mathematical description of both the signal and mediums defines space embracing of the relevant interfacing devices. As a result, a wide range of the nano-bio-transducers allow both delivering the variety of ionized biosignals and interface the bioEM signals with further stages of electronic systems. The space coverage and transducing values properties of the state-of-the-art magnetic interfaces are summarized, and directions for their future development are deduced.