Main Problems of Nanostructured Materials Science

Andrievski, R.A.

doi:10.4028/www.scientific.net/msf.494.113

Cited by 9 publications

(9 citation statements)

References 21 publications

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“…(a) The melting point of Al 2 O 3 -Cr 2 O 3 alloy as a function of Cr 2 O 3 content and the particle size; (b) the melting point of indium as a function of the particle size for two different preparation procedures; (c) the phase diagram for a germanium-based alloy and two different particle sizes—54 and 32 nm; (d) local density of states, a measure of the band gap, decreasing in direct proportion to the particle volume and indicating a metal-insulator transition at V ≈ 0.01–1 nm 3 in case of three different metals: Au, Cd and Ag, but not Pd. Reprinted with permissions from [6], L. H. Liang, et al, Size-dependent continuous binary solution phase diagram.…”

Section: Figurementioning

confidence: 99%

“…In Figure 3(a), shown is the melting point of Al 2 O 3 –Cr 2 O 3 alloy, approximately constant with respect to the chromate content, but greatly depending on the particle size when the latter reaches the nanosized range 6 ( < 100 nm by convention, 3 although this limit is often taken to be 300 nm in the biomedical milieu 4 ). A greater difference in the melting point is produced by a drop in the particle size from 20 to 8 nm than by reducing the particle diameter from 100 to 20 nm, demonstrating that not only does a micro-to-nano transition in the grain size of a material entail drastic changes in the material properties, but also that a minor change in the grain size at the nanoscale can have far more drastic effects on the materials properties than the very transition from bulk to nano.…”

Section: Introduction: How Nanoscience Sprang Into Lifementioning

confidence: 99%

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Entering the Era of Nanoscience: Time to Be So Small Vuk Uskokovíc

Uskoković¹

2013

Journal of Biomedical Nanotechnology

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The field of nanoscience has produced more hype than probably any other branch of materials science and engineering in its history. Still, the potentials of this new field largely lay undiscovered ahead of us; what we have learnt so far with respect to the peculiarity of physical processes on the nanoscale is only the tip of an iceberg. Elaborated in this critical review is the idea that the surge of interest in physical chemistry of phenomena at the nanoscale presents a natural consequence of the spatial refinement of the human ability to controllably manipulate the substratum of our physical reality. Examples are given to illustrate the sensitivity of material properties to grain size on the nanoscale, a phenomenon that directly contributed to the rise of nanoscience as a special field of scientific inquiry. Main systemic challenges faced by the present and future scientists in this field are also mentioned. In part, this perspective article resembles standing on the constantly expanding seashore of the coast of nanoscience and nanoengineering and envisioning the parts of the island where the most significant advances may be expected to occur and where, therefore, most of the attention of scientist in this field is to be directed: (a) crossing the gap between life science and materials science; (b) increasing experimentation sensitivity; (c) crisscrossing theory and experiments; and (d) conjoining top-down and bottom-up synthetic approaches. As for materials and the application areas discussed, a special emphasis is placed on calcium phosphate nanoparticles and their usage in controlled drug delivery devices and other applications of biomedical relevance. It is argued that the properties of nanoparticles as drug carriers often comprise the critical determinant for the efficacy of the drug therapy. Therefore, the basic properties of nanoparticles to be optimized for the purpose of maximizing this efficacy are discussed: size, size distribution, morphology, polymorphic nature, crystallinity, biocompatibility, biodegradability, drug elution profiles, and aggregation propensity.

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Section: Figurementioning

confidence: 99%

Section: Introduction: How Nanoscience Sprang Into Lifementioning

confidence: 99%

Entering the Era of Nanoscience: Time to Be So Small Vuk Uskokovíc

Uskoković¹

2013

Journal of Biomedical Nanotechnology

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“…Since the volume fraction of grain boundaries (GB's) increases with decreasing grain size, it is important to gain a full understanding of GB's. 2,3 Even more, substructures of the GB morphology, in particular triple junctions (TJ's), that is, the line-shaped topological defect at which three boundaries merge, will presumably control material properties, if grain size scales down to the nanometer range. Particular physical properties of TJ's are proposed in theoretical work 4 and computer simulation 5 while experimental evidence is rare.…”

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confidence: 99%

Triple junction segregation in nanocrystalline multilayers

2011

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Triple junctions (TJ's), topologically required linear defects of grain boundary structure, are suggested to control the behavior of nanocrystalline material. However, measurements of their properties are rare. With atom probe tomography, reliable analysis of singular features of the grain boundary structure becomes possible. We report microscopic measurements of segregation along individual TJ's in Fe/Cr. By segregation to TJ's nanometric tubular objects of distinct properties are formed. The determined segregation enthalpy of 0.076 eV indicates that TJ's provide considerable free volume similar to free surfaces.

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“…As structural components become smaller, the number of interfaces, whose properties may differ from those in larger-grained ceramics, increases [7,8].…”

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confidence: 99%

“…The papers [7,8] report that a homogenous fine microstructure is the main requirement for sintered ZrO 2 -based ceramic materials with improved physical and technical properties. Figures 7 and 8 show that the samples produced by CIP under different pressures have different microstructures after sintering.…”

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confidence: 99%

Refractory and ceramic materials

Dudnik

Shevchenko

Ruban

et al. 2007

Powder Metall Met Ceram

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The paper examines the consolidation of 95 mole% ZrO 2 -2 mole% CeO 2 -3 mole% Y 2 O 3 nanocrystalline powder in cold uniaxial cold isostatic pressing (60 and 120 MPa), and sintering. Five starting powders are produced by processing a suspension after hydrothermal decomposition in different conditions. It is established that a homogeneous microstructure forms only in a material from the powder subjected to two homogenizing grindings. After cold uniaxial pressing and cold isostatic pressing, the sintered samples reach a relative density of 0.96 to 0.94. The bending strength is 600 to 660 MPa. The efficient consolidation of ceramics requires comprehensive processing of starting nanocrystalline powders to modify their morphology.In order to produce ZrO 2 -based bioimplants, materials with a stable structure and high bending strength and critical fracture toughness are needed [1,2]. It is believed that ZrO 2 -based materials, ZrO 2 -Y 2 O 3 system, possess excellent mechanical properties but are susceptible to low-temperature aging in humid environment. Therefore, they have limited application in developing new types of bioimplants [1, 3]. These materials become more resistant to lowtemperature aging if Y 2 O 3 is partly replaced by CeO 2 [4,5]. Transformation hardening is the main contributor to the desired properties. The main requirement in producing transformation-hardened ceramics is to form a porousless fine structure consisting of tetragonal zirconia grains (T-ZrO 2 ), which can transform into another phase under applied stress [6].Nanocrystalline ZrO 2 -based powders used as starting materials for bioimplants cause problems associated with the size effect and in-service microstructural stability. As structural components become smaller, the number of interfaces, whose properties may differ from those in larger-grained ceramics, increases [7,8].The objective of this paper is to establish features peculiar to the consolidation of nanocrystalline 95 ZrO 2 -2 CeO 2 -3 Y 2 O 3 powder * 95 ZrO 2 -2 CeO 2 -3 Y 2 O 3 depending on processing conditions. * The powder composition is in mole%.

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Main Problems of Nanostructured Materials Science

Cited by 9 publications

References 21 publications

Entering the Era of Nanoscience: Time to Be So Small Vuk Uskokovíc

Entering the Era of Nanoscience: Time to Be So Small Vuk Uskokovíc

Triple junction segregation in nanocrystalline multilayers

Refractory and ceramic materials

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