In the last 30 days

• Open/close Challenges and breakthroughs in recent research on self-assembly

  Katsuhiko Ariga et al 2008 Sci. Technol. Adv. Mater. 9 014109 Tag this article

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  The controlled fabrication of nanometer-scale objects is without doubt one of the central issues in current science and technology. However, existing fabrication techniques suffer from several disadvantages including size-restrictions and a general paucity of applicable materials. Because of this, the development of alternative approaches based on supramolecular self-assembly processes is anticipated as a breakthrough methodology. This review article aims to comprehensively summarize the salient aspects of self-assembly through the introduction of the recent challenges and breakthroughs in three categories: (i) types of self-assembly in bulk media; (ii) types of components for self-assembly in bulk media; and (iii) self-assembly at interfaces.

• Open/close Technological advances in electrospinning of nanofibers

  Wee-Eong Teo et al 2011 Sci. Technol. Adv. Mater. 12 013002 Tag this article

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  Progress in the electrospinning techniques has brought new methods for the production and construction of various nanofibrous assemblies. The parameters affecting electrospinning include electrical charges on the emerging jet, charge density and removal, as well as effects of external perturbations. The solvent and the method of fiber collection also affect the construction of the final nanofibrous architecture. Various techniques of yarn spinning using solid and liquid surfaces as well as surface-free collection are described and compared in this review. Recent advances allow production of 3D nanofibrous scaffolds with a desired microstructure. In the area of tissue regeneration and bioengineering, 3D scaffolds should bring nanofibrous technology closer to clinical applications. There is sufficient understanding of the electrospinning process and experimental results to suggest that precision electrospinning is a real possibility.

• Open/close Hydrothermal growth of ZnO nanostructures

  Sunandan Baruah and Joydeep Dutta 2009 Sci. Technol. Adv. Mater. 10 013001 Tag this article

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  One-dimensional nanostructures exhibit interesting electronic and optical properties due to their low dimensionality leading to quantum confinement effects. ZnO has received lot of attention as a nanostructured material because of unique properties rendering it suitable for various applications. Amongst the different methods of synthesis of ZnO nanostructures, the hydrothermal method is attractive for its simplicity and environment friendly conditions. This review summarizes the conditions leading to the growth of different ZnO nanostructures using hydrothermal technique. Doping of ZnO nanostructures through hydrothermal method are also highlighted.

• Open/close New functionalities in abundant element oxides: ubiquitous element strategy

  Hideo Hosono et al 2011 Sci. Technol. Adv. Mater. 12 034303 Tag this article

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  While most ceramics are composed of ubiquitous elements (the ten most abundant elements within the Earth's crust), many advanced materials are based on rare elements. A 'rare-element crisis' is approaching owing to the imbalance between the limited supply of rare elements and the increasing demand. Therefore, we propose a 'ubiquitous element strategy' for materials research, which aims to apply abundant elements in a variety of innovative applications. Creation of innovative oxide materials and devices based on conventional ceramics is one specific challenge. This review describes the concept of ubiquitous element strategy and gives some highlights of our recent research on the synthesis of electronic, thermionic and structural materials using ubiquitous elements.

• Open/close Present status of amorphous In–Ga–Zn–O thin-film transistors

  Toshio Kamiya et al 2010 Sci. Technol. Adv. Mater. 11 044305 Tag this article

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  The present status and recent research results on amorphous oxide semiconductors (AOSs) and their thin-film transistors (TFTs) are reviewed. AOSs represented by amorphous In–Ga–Zn–O (a-IGZO) are expected to be the channel material of TFTs in next-generation flat-panel displays because a-IGZO TFTs satisfy almost all the requirements for organic light-emitting-diode displays, large and fast liquid crystal and three-dimensional (3D) displays, which cannot be satisfied using conventional silicon and organic TFTs. The major insights of this review are summarized as follows. (i) Most device issues, such as uniformity, long-term stability against bias stress and TFT performance, are solved for a-IGZO TFTs. (ii) A sixth-generation (6G) process is demonstrated for 32'' and 37'' displays. (iii) An 8G sputtering apparatus and a sputtering target have been developed. (iv) The important effect of deep subgap states on illumination instability is revealed. (v) Illumination instability under negative bias has been intensively studied, and some mechanisms are proposed. (vi) Degradation mechanisms are classified into back-channel effects, the creation of traps at an interface and in the gate insulator, and the creation of donor states in annealed a-IGZO TFTs by the Joule heating; the creation of bulk defects should also be considered in the case of unannealed a-IGZO TFTs. (vii) Dense passivation layers improve the stability and photoresponse and are necessary for practical applications. (viii) Sufficient knowledge of electronic structures and electron transport in a-IGZO has been accumulated to construct device simulation models.

• Open/close Electrodeposition of nanostructured coatings and their characterization—a review

  Injeti Gurrappa and Leo Binder 2008 Sci. Technol. Adv. Mater. 9 043001 Tag this article

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  Nanostructured materials have gained importance in recent years due to their significantly enhanced properties. In particular, electrochemistry has a special role in producing a variety of nanostructured materials. In the current review, we discuss the superiority of electrochemical deposition techniques in synthesizing various nanomaterials that exhibit improved characteristics compared with materials produced by conventional techniques, as well as their classification, synthesis routes, properties and applications. The superior properties of a nanostructured nickel coating produced by electrochemical deposition are outlined. The properties of various nanostructured coating materials produced by electrochemical techniques are also described. Finally, the importance of nanostructured coatings in industrial applications as well as their potential in future technologies is emphasized.

• Open/close Novel approach to the fabrication of an artificial small bone using a combination of sponge replica and electrospinning methods

  Yang-Hee Kim and Byong-Taek Lee 2011 Sci. Technol. Adv. Mater. 12 035002 Tag this article

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  In this study, a novel artificial small bone consisting of ZrO ₂-biphasic calcium phosphate/polymethylmethacrylate-polycaprolactone-hydroxyapatite (ZrO ₂-BCP/PMMA-PCL-HAp) was fabricated using a combination of sponge replica and electrospinning methods. To mimic the cancellous bone, the ZrO ₂/BCP scaffold was composed of three layers, ZrO ₂, ZrO ₂/BCP and BCP, fabricated by the sponge replica method. The PMMA-PCL fibers loaded with HAp powder were wrapped around the ZrO ₂/BCP scaffold using the electrospinning process. To imitate the Haversian canal region of the bone, HAp-loaded PMMA-PCL fibers were wrapped around a steel wire of 0.3 mm diameter. As a result, the bundles of fiber wrapped around the wires imitated the osteon structure of the cortical bone. Finally, the ZrO ₂/BCP scaffold was surrounded by HAp-loaded PMMA-PCL composite bundles. After removal of the steel wires, the ZrO ₂/BCP scaffold and bundles of HAp-loaded PMMA-PCL formed an interconnected structure resembling the human bone. Its diameter, compressive strength and porosity were approximately 12 mm, 5 MPa and 70%, respectively, and the viability of MG-63 osteoblast-like cells was determined to be over 90% by the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay. This artificial bone shows excellent cytocompatibility and is a promising bone regeneration material.

• Open/close Silicon-based oxynitride and nitride phosphors for white LEDs—A review

  Rong-Jun Xie and Naoto Hirosaki 2007 Sci. Technol. Adv. Mater. 8 588 Tag this article

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  As a novel class of inorganic phosphors, oxynitride and nitride luminescent materials have received considerable attention because of their potential applications in solid-state lightings and displays. In this review we focus on recent developments in the preparation, crystal structure, luminescence and applications of silicon-based oxynitride and nitride phosphors for white light-emitting diodes (LEDs). The structures of silicon-based oxynitrides and nitrides (i.e., nitridosilicates, nitridoaluminosilicates, oxonitridosilicates, oxonitridoaluminosilicates, and sialons) are generally built up of networks of crosslinking SiN ₄ tetrahedra. This is anticipated to significantly lower the excited state of the 5d electrons of doped rare-earth elements due to large crystal-field splitting and a strong nephelauxetic effect. This enables the silicon-based oxynitride and nitride phosphors to have a broad excitation band extending from the ultraviolet to visible-light range, and thus strongly absorb blue-to-green light. The structural versatility of oxynitride and nitride phosphors makes it possible to attain all the emission colors of blue, green, yellow, and red; thus, they are suitable for use in white LEDs. This novel class of phosphors has demonstrated its superior suitability for use in white LEDs and can be used in bichromatic or multichromatic LEDs with excellent properties of high luminous efficacy, high chromatic stability, a wide range of white light with adjustable correlated color temperatures (CCTs), and brilliant color-rendering properties.

• Open/close Zinc stannate nanostructures: hydrothermal synthesis

  Sunandan Baruah and Joydeep Dutta 2011 Sci. Technol. Adv. Mater. 12 013004 Tag this article

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  Nanostructured binary semiconducting metal oxides have received much attention in the last decade owing to their unique properties rendering them suitable for a wide range of applications. In the quest to further improve the physical and chemical properties, an interest in ternary complex oxides has become noticeable in recent times. Zinc stannate or zinc tin oxide (ZTO) is a class of ternary oxides that are known for their stable properties under extreme conditions, higher electron mobility compared to its binary counterparts and other interesting optical properties. The material is thus ideal for applications from solar cells and sensors to photocatalysts. Among the different methods of synthesizing ZTO nanostructures, the hydrothermal method is an attractive green process that is carried out at low temperatures. In this review, we summarize the conditions leading to the growth of different ZTO nanostructures using the hydrothermal method and delve into a few of its applications reported in the literature.

• Open/close Biopolymeric nanoparticles

  Sushmitha Sundar et al 2010 Sci. Technol. Adv. Mater. 11 014104 Tag this article

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  This review on nanoparticles highlights the various biopolymers (proteins and polysaccharides) which have recently revolutionized the world of biocompatible and degradable natural biological materials. The methods of their fabrication, including emulsification, desolvation, coacervation and electrospray drying are described. The characterization of different parameters for a given nanoparticle, such as particle size, surface charge, morphology, stability, structure, cellular uptake, cytotoxicity, drug loading and drug release, is outlined together with the relevant measurement techniques. Applications in the fields of medicine and biotechnology are discussed along with a promising future scope.