"If you make a strontium titanate film very thin, all of a sudden it becomes ferroelectric at room temperature," "If you make it thicker, ferroelectricity disappears. That's very strange, as it goes completely counter to all the common knowledge regarding the thickness effect on ferroelectric properties." says Alexei Gruverman, a University of Nebraska-Lincoln physics and astronomy professor who worked on the research.
This incongruent materials ferroelectric behaviour is explainded in their communication cf link below
Physicists defy conventional wisdom to identify ferroelectric material | EurekAlert! Science News
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Showing posts with label Nanotechnology. Show all posts
Showing posts with label Nanotechnology. Show all posts
Monday, 21 September 2015
Saturday, 15 December 2012
Nanomanufacturing of biomaterials - Review article from Materials Today, November 2012.
It is always interesting and useful to enlarge one's knowledge in the rapidly expanding field of Materials Science and what could be better than a review paper to keep up-to-date. Here is a link to nanotechnology, nanomanufacturing and biomaterials.
Nanomanufacturing of biomaterials - Review article - Materials Today
Nanomanufacturing of biomaterials - Review article - Materials Today
Friday, 26 October 2012
News & Videos: Manufacturing complex 3D metallic structures at nanoscale made possible - Aalto University Finland
Manufacturing complex 3D metallic structures at nanoscale made possible
18.10.2012
The fabrication of many objects, machines, and devices around us rely on the controlled deformation of metals by industrial processes such as bending, shearing, and stamping. Is this technology transferrable to nanoscale? Can we build similarly complex devices and machines with very small dimensions?
Scientists from Aalto University in Finland and the University of Washington in the US have just demonstrated this to be possible. By combining ion processing and nanolithography they have managed to create complex three-dimensional structures at nanoscale.
The discovery follows from a quest for understanding the irregular folding of metallic thin films after being processed by reactive ion etching.
– We were puzzled by the strong-width-dependent curvatures in the metallic strips. Usually initially-strained bilayer metals do not curl up this way, explains Khattiya Chalapat from Aalto University.
The puzzle began to unravel when Chalapat noticed, together with Dr. Hua Jiang, that the Ti peak was absent from the EDX spectra of folded Ti/Al bilayers.
Further experiments at the O.V. Lounasmaa Laboratory confirmed that the strips bend upward with strong width-dependent curvatures if the bottom layer of the strips is made more reactive to ions than the top surface.
In nature, similar geometrical effects take place in self-organization directly observable to the human eye. When dandelion flowers bloom, one may try cutting the flower stem into small strips; put them in water, and the strips will fold with observable width-dependent curvatures due to differences in the water absorption between the inside and outside parts of the stem.
– Our idea was to find a way to adapt these natural processes to nanofabrication. This led us to an incidental finding that a focused ion beam can locally induce bending with nanoscale resolution.
The technology has various applications in the fabrication of nanoscale devices. The structures are surprisingly resilient: the team found them to be quite sturdy and robust under a variety of adverse conditions, such as electrostatic discharge and heating.
– Because the structures are so small, the coupling and the magnitude of typical nanoscale forces acting on them would be commensurately small, reminds Docent Sorin Paraoanu, the leader of the Kvantti research group, Aalto University.
– As for applications, we have demonstrated so far that these structures can capture and retain particles with dimensions of the order of a micrometer. However, we believe that we are just scratching the tip of the iceberg: a comprehensive theory of ion-assisted self-assembly processes is yet to be reached, notes Paraoanu.
The research has been recently published in the Early View edition of Advanced Materials.
Khattiya Chalapat and Sorin Paraoanu would like to give credit to the Aalto University research facilities for microfabrication and imaging at Micronova Centre for Micro and Nanotechnology and the Nanomicroscopy Center in Finland.
Further information:
Khattiya Chalapat, Ph.D. student
O. V. Lounasmaa Laboratory, Aalto University
khattiya.chalapat@aalto.fi
Khattiya Chalapat, Ph.D. student
O. V. Lounasmaa Laboratory, Aalto University
khattiya.chalapat@aalto.fi
Sorin Paraoanu, Docent, Group Leader
O. V. Lounasmaa Laboratory, Aalto University
sorin.paraoanu@aalto.fi
O. V. Lounasmaa Laboratory, Aalto University
sorin.paraoanu@aalto.fi
News: Manufacturing complex 3D metallic structures at nanoscale made possible - Aalto University
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Tribology_At the Nanoscale, Graphite Can Turn Friction Upside Down_fromNIST
If you ease up on a pencil, does it slide more easily? Sure. But maybe not if the tip is sharpened down to nanoscale dimensions. A team of researchers at the National Institute of Standards and Technology (NIST) has discovered that if graphite (the material in pencil "lead") is sticky enough, as measured by a nanoscale probe, it actually becomes harder to slide a tip across the material's surface as you decrease pressure—the exact opposite of our everyday experience.
Technically, this leads to an effectively "negative coefficient of friction," something that has not been previously seen, according to team leader Rachel Cannara. Graphite, Cannara explains, is one of a special class of solids called "lamellar" materials, which are formed from stacks of two-dimensional sheets of atoms. The sheets are graphene, a single-atom-thick plane of carbon atoms that are arranged in a hexagonal pattern. Graphene has a number of exotic electrical and material properties that make it attractive for micro- and nanoelectromechanical systems with applications ranging from gas sensors and accelerometers to resonators and optical switches.
Zhao Deng, a University of Maryland postdoctoral researcher at NIST's Center for Nanoscale Science and Technology, noted some odd data while experimenting on graphite with an atomic force microscope (AFM). Deng was measuring the friction forces on the nanoscale tip of an AFM tracking across the graphite as he modified the "stickiness" of the surface by allowing tiny amounts of oxygen to adsorb to the topmost graphene layer.
Deng found that when the adhesive force between the graphene and the stylus became greater than the graphene layer's attraction to the graphite below, reducing the pressure on the stylus made it harder to drag the tip across the surface—a negative differential friction.
Backed by theoretical simulations performed by collaborators from NIST and Tsinghua University in Beijing, Cannara's team found that, after the AFM tip has been pressed into the graphite surface, if the attractive force is high enough, the tip can pull a small localized region of the surface layer of graphene away from the bulk material, like raising a nanoscale bubble from the surface. Pushing that deformation around takes more work than sliding over a flat surface. Therefore, whenever the researchers pressed the AFM tip against the sticky graphite surface and then tried to pull the two apart, they measured an increase in friction force with a sensitivity in the tens of piconewtons.
"Once we have a complete model describing how these graphene sheets deform under repeated loading and sliding at the nanoscale—which we're working on now—friction force microscopy may be the most direct way to measure the energy that binds these layered materials together. And, since it's nondestructive, the measurement can be performed on working devices," Cannara says. Understanding how the sheets interact with each other and with other parts of a device would help quantify the energy required to produce individual sheets from bulk material, assess device operation, and assist in formulating new structures based on layered materials, she says.
* Z. Deng, A. Smolyanitsky, Q. Li, X.-Q. Feng and R. J. Cannara. Adhesion-dependent negative friction coefficient on chemically modified graphite at the nanoscale. Nature Materials. Published online: 14 October 2012 | doi:10.1038/nmat3452.
Slip Sliding Our Way: At the Nanoscale, Graphite Can Turn Friction Upside Down
Friday, 7 September 2012
Nano-material molecular electric conductivity is predicted to offer up to four times bulk conductivity depending on the material-molecules
The following news release from Brookhaven National Lab entitled
"Electronics Play By a New Set of Rules at the Molecular Scale"
September 2, 2012, By Aviva Hope Rutkin"
Nano-material molecular electric conductivity is predicted to offer up to four times bulk conductivity depending on the material-molecules
In a paper published in Nature Nanontechnology onSeptember 2, 2012, scientists from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia University’s departments of Chemistry and of Applied Physics explore the laws that govern electronic conductance in molecular scale circuits.
“Everyone who has worked with basic electronic circuits knows that there are some simple rules of the road, like Ohm’s Law,” explains collaborator Mark Hybertsen, a physicist at Brookhaven’sCenter for Functional Nanomaterials (CFN). Hybertsen provided the theory to model the observed circuit behavior with the CFN’s computational tools. “For several years we have been asking fundamental questions to probe how those rules might be different if the electronic circuit is shrunk down to the scale of a single molecule.”
Conductance measures the degree to which a circuit conducts electricity. In a simple circuit, if you hook the resistors up in parallel, the electrons can flow through two different paths. In this case, the conductance of the full circuit will simply be the sum of the conductance of each resistor.
However, in a molecular circuit, the rules that govern current flow now involve fundamental quantum mechanics. In most single-molecule circuits, the molecules do not behave like conventional resistors; instead, the electrons tunnel through the molecule. When the molecule offers two pathways in parallel, the wave-like movement of an electron can dramatically change the way conductance adds up. For several years, experts in nanotechnology have suspected—but not proven—that quantum interference effects make the conductance of a circuit with two paths up to four times higher than the conductance of a circuit with a single path.
In order to investigate these quantum mechanical effects further, the scientists needed to construct their own controllable nano-size circuits. Working with Ronald Breslow’s group at Columbia, they designed and synthesized a series of molecules to use in the experiment.
“Reliably making a circuit from a single molecule is really challenging,” says Latha Venkataraman, a Columbia Engineering Applied Physics professor whose group perfected the method used to make the molecular circuits. “Imagine trying to touch the two ends of a molecule that is only ten atoms long.”
To make the circuits, Venkataraman’s group adapted a scanning tunneling microscope (STM) apparatus to repeatedly press a sharp gold tip into another gold electrode and then pull it away. When this junction breaks, there is a moment when the gap between the two pieces of gold is a perfect fit for the molecule. Once the circuit system is set up, the conductance measurement is fast and can be repeated thousands of times to get statistically reliable data.
Using this approach, the scientists discovered that the molecules with two built-in pathways like the one visualized in the figure at right had a conductance that was greater than the sum of each arm’s conductance, although the increase was not as large as they had anticipated. In order to understand this effect better, Columbia’s Hector Vasquez worked with Hybertsen to computationally simulate the quantum mechanical transmission of an electron through each circuit.
“Both the measurements and the simulations show that the molecules with two parallel paths can have a conductance that is bigger than two times that of molecule with a single path,” said Hybertsen. “This is the signature that the quantum interference effect is playing a role.”
The group suspects that other factors, such as the nature of the molecule’s bond to the electrodes, need to be considered when calculating the conductance of a molecular circuit. They are currently looking into other central questions about molecular electronics, including how the device changes when different metals are used.
This research was funded primarily by the National Science Foundation and the New York State Office of Science, Technology, and Academic Research. Columbia’s Rachid Skouta and Severin Schneebeli synthesized the experiment molecules with Ronald Breslow and Masha Kamanetska carried out the conductance measurements. The CFN at Brookhaven Lab is supported by the DOE’s Office of Science. ""
Refs: brough to my attention by:
MaterialsToday in their article entitled "Electronics, at the molecular scale"
"06 September 2012.
Tuesday, 20 September 2011
Moore's Law and beyond _ Where Semiconductor Science is going_Interdisciplinary Public and Private Partnership Funded Projects in the Semiconductor Field
The joint NSF-NRI grants were awarded to the following projects in nanoelectronics research and can be viewed in detail at the accompanying links:
• Scalable Sensing, Storage and Computation with a Rewritable Oxide Nanoelectronics Platform, directed by Jeremy Levy at University of Pittsburgh.
• Integrated Biological and Electronic Computation at the Nanoscale, directed by Timothy Lu at MIT.
• Developing a Graphene Spin Computer: Materials, Nano-Devices, Modeling, and Circuits, directed by Roland Kawakami at University of California at Riverside.
• Meta-Capacitance and Spatially Periodic Electronic Excitation Devices (MC-SPEEDs), directed by Jonathan Spanier at Drexel University.
• Hybrid Spintronics and Straintronics: New Technology for Ultra-Low Energy Computing and Signal Processing Beyond the Year 2020, directed by Supriyo Bandyopadhyay at Virginia Commonwealth University.
• Charge-Density-Wave Computational Fabric: New State Variables and Alternative Material Implementation, directed by Alexander Balandin at University of California at Riverside.
• Ultimate Electronic Device Scaling Using Structurally Precise Graphene Nanoribbons, directed by Paulette Clancy at Cornell University.
• Nanoelectronics with Mixed-valence Molecular QCA, directed by Craig Lent at University of Notre Dame.
• Scalable Perpendicular All-Spin Non-Volatile Logic Devices and Circuits with Hybrid Interconnection, directed by Jian-Ping Wang at University of Minnesota at Twin Cities.
• Physics-Inspired Non-Boolean Computation Based on Spatial-Temporal Wave Excitations, directed by Wolfgang Porod at University of Notre Dame.
• Novel Quantum Switches Using Heterogeneous Atomically Layered Nanostructures, directed by Philip Kim at Columbia University.
• Superlattice-FETs, Gamma-L-FETs and Tunnel-FETs: Materials, Circuits and Devices for Fast, Ultra-Low Power, directed by Mark Rodwell at University of California at Santa Barbara.
These 12 NSF-NRI joint grants expand and strengthen the commitment to this public-private partnership program, which is in its sixth year.
NSF Divisions participating in this competition are the Division of Electrical, Communications and Cyber Systems (ECCS) in the Directorate for Engineering, the Division of Materials Research (DMR) and the Division of Chemistry (CHE) in the Directorate for Mathematical and Physical Sciences, and the Division of Computing and Communications Foundations (CCF) in the Directorate for Computer and Information Science and Engineering,
Companies participating in NRI are GLOBALFOUNDRIES, IBM, Intel Corporation, Micron Technology and Texas Instruments. These companies assign researchers to interact with the university teams. This kind of university-industry engagement will be instrumental in order for NRI to reach its goal of demonstrating the feasibility of novel computing devices in simple computer circuits during the next five to 10 years.
REFERENCE 1
via The regular progammed Yahoo Materials Science Search of 19 Sept 2011
• Scalable Sensing, Storage and Computation with a Rewritable Oxide Nanoelectronics Platform, directed by Jeremy Levy at University of Pittsburgh.
• Integrated Biological and Electronic Computation at the Nanoscale, directed by Timothy Lu at MIT.
• Developing a Graphene Spin Computer: Materials, Nano-Devices, Modeling, and Circuits, directed by Roland Kawakami at University of California at Riverside.
• Meta-Capacitance and Spatially Periodic Electronic Excitation Devices (MC-SPEEDs), directed by Jonathan Spanier at Drexel University.
• Hybrid Spintronics and Straintronics: New Technology for Ultra-Low Energy Computing and Signal Processing Beyond the Year 2020, directed by Supriyo Bandyopadhyay at Virginia Commonwealth University.
• Charge-Density-Wave Computational Fabric: New State Variables and Alternative Material Implementation, directed by Alexander Balandin at University of California at Riverside.
• Ultimate Electronic Device Scaling Using Structurally Precise Graphene Nanoribbons, directed by Paulette Clancy at Cornell University.
• Nanoelectronics with Mixed-valence Molecular QCA, directed by Craig Lent at University of Notre Dame.
• Scalable Perpendicular All-Spin Non-Volatile Logic Devices and Circuits with Hybrid Interconnection, directed by Jian-Ping Wang at University of Minnesota at Twin Cities.
• Physics-Inspired Non-Boolean Computation Based on Spatial-Temporal Wave Excitations, directed by Wolfgang Porod at University of Notre Dame.
• Novel Quantum Switches Using Heterogeneous Atomically Layered Nanostructures, directed by Philip Kim at Columbia University.
• Superlattice-FETs, Gamma-L-FETs and Tunnel-FETs: Materials, Circuits and Devices for Fast, Ultra-Low Power, directed by Mark Rodwell at University of California at Santa Barbara.
These 12 NSF-NRI joint grants expand and strengthen the commitment to this public-private partnership program, which is in its sixth year.
NSF Divisions participating in this competition are the Division of Electrical, Communications and Cyber Systems (ECCS) in the Directorate for Engineering, the Division of Materials Research (DMR) and the Division of Chemistry (CHE) in the Directorate for Mathematical and Physical Sciences, and the Division of Computing and Communications Foundations (CCF) in the Directorate for Computer and Information Science and Engineering,
Companies participating in NRI are GLOBALFOUNDRIES, IBM, Intel Corporation, Micron Technology and Texas Instruments. These companies assign researchers to interact with the university teams. This kind of university-industry engagement will be instrumental in order for NRI to reach its goal of demonstrating the feasibility of novel computing devices in simple computer circuits during the next five to 10 years.
REFERENCE 1
via The regular progammed Yahoo Materials Science Search of 19 Sept 2011
Friday, 11 March 2011
Surface chemistry: A close look at hydrophobicity_Wetting_non-Wetting_Bulk Steelmaking Macro to Nanotechnology and Biomimicry
This post was motivated by a recent publication (14 Feb. 2011 in Nature Asia Materials) entitled
Surface chemistry: A close look at hydrophobicity : research highlight : NPG Asia Materials (ref. 1)
Much progress has been made in understanding the phenomena involved in the wetting of solid surfaces by liquids, in the characterisation of wetting phenomena since Charles Macintosh (FRS) chemist and engineer famous for the impermeable named after him (1766 – 1843) for that that matter since my very first study as young,high temperature physical chemistry,research scientific officer involved in "wetting- non-wetting of refractory surfaces by liquid steel (mpt.1500°C) so fundamental to steelmaking and it's manufacturing process improvement.(1969-71) It appeared to provide a surprising historical insight into the study of wetting, hydrophobia-hydrophilic as well as an occasion to revisit themes treated pragmatically in my very first study project involving the formation of gas bubbles on refractory surfaces in steel, perhaps re-situate it in what has today become a flourishing inspirational approach to many biomimetic material innovations. Our focus at the time (1970) was the then new vacuum degassing DH and RH processes whereby liquid steel is recycled through a vacuum chamber. Deoxidation is by carbon forming CO/CO2 gas bubbles formed under the prevailing vacuum conditions. Often the liquid steel circulation was hindered in the narrow recirculation legs by unwanted CO/CO2 gas bubbles. We confirmed the role of liquid wetting, active or unwetted pore size, the influence of choice of refractory materials, and the combined influence of the overhead atmospheric pressure and the pressure of the head weight of liquid steel. The total pressure was varied by reducing the atmospheric pressure. Data is shown below:
Ref. 2 The growth of carbon monoxide bubbles on refractory surfaces during vacuum degassing of iron melts. J. Alexander, G.S.F Hazeldean, M.W. Davies Sheffield Conf. 1971 and BISRA -Corp Labs of British Steel Corp. Report CH/28/71.
If I personally did not follow-up this applied research in bulk liquid metal degassing, it did stand me in good stead for rapidly coming to terms with gas bubble phenomena in liquid steel and special alloys. For example Fe-Ni and Fe-Ni-Co alloys, Invars and Covars highly sensitive to CO gas solubility and rimming or degassing during solidification. The larger the ingot the more difficult it is to solidify and subsequently remove remaining traces of gas blow-holes. Nevertheless ingot sizes were increased from 4T to 10T and even to 18T. Similarly improvements were made in VIM-vacuum induction melting and refining and VAR-vacuum arc remelting etc. all stemming from intimate knowledge of C deoxidation reaction its theoretical and practical limitations and of the physics and chemistry of wetting.
If I and worse the reader feels that this is old-hat stuff, I and hopefully the reader like me will be most encouraged by the historical background referenced in the title paper:
Surface chemistry: A close look at hydrophobicity : research highlight : NPG Asia Materials (14 Feb. 2011) Ref. 3.
Wenzel's referenced work is "Wenzel RN (1936) Resistance of solid surfaces to wetting by water. Ind Eng Chem" and Cassies referenced work is Cassie ABD, Baxter S (1944) Wettability of porous surfaces. Trans Faraday Soc 40:546–551.28:988–994. [ WENZEL STATE _ WENZEL-CASSIE-TRANSITION_free from PNAS.ORG [Pdf format] (Ref. 3)
Of course lower temperature (RT) phenomena and modern computing techniques and computer technological advance readily allow molecular dynamic (MD) simulations to be carried out. If accent in the 1960-1980's focused on macro-phenomena and increasing productivity and economies of size. Recent approaches focus more and more on the infinitely small-nanoscience and technology first driven by micro-electronics (Moore's Law ) and much more recently inspired by biomimicry cf for example The Biomimicry Institute.
The types of applications, inventions, innovations arising from nanotechnology and the biomimetic approach are given in ref. 4 below.
NB. Recent great mind who moved from solid state physics to explore
"Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves"
and on to soft materials is the late and much regreted Pierre-Gilles de Gennes, who associated with Francoise Brochard-Wyart and David Quere authored the book in the above title. cf also amazon's offer in Books below.
Refs:
1. Surface chemistry: A close look at hydrophobicity : research highlight : NPG Asia Materials
2. Ref. 2 The growth of carbon monoxide bubbles on refractory surfaces during vacuum degassing of iron melts. J. Alexander, G.S.F Hazeldean, M.W. Davies Sheffield Conf. 1971 and BISRA -Corp Labs of British Steel Corp. Report CH/28/71.
3. WENZEL STATE - WENZEL CASSIE [Pdf]
4. Hydrophobicity - Superhydrophobicity
5. Good overall introduction to physics of Wetting, Adhesion, Biomimicry, Friction:
Nick Fang's Lecture_Wetting_Adhesion_Biomimicry_Friction_Macro to Nano [pdf]
RELATED POSTS:
1. Whisky - Chemical up-date from the RCS-Chemistry World
2. Water repellent properties, Biomimicry, Self Assembling Molecules, Network of micro- nanowires, excellent imagery in "Nanomaterials: Cu Water Strider .
3. Metaklett-steel grips, Biomimicry and Shape Memory Alloy meanders
4. Nanotechnology - to many to list - use blog search tool - top left.
GOOGLE BOOKS:
Tuesday, 16 March 2010
Nanoscale,Nanomaterials_Basics_Calculate numbers of surface to volume atoms and much more.
NB. Embedded Google book (EB) trial, read on and scroll down for relevent pages.
and first experience with Wolfram Alpha. Both postive, a pleasure.
Having "dived in at the deep end" on a couple of recent posts, only just managing to "scratch the surface" in related post 1_ "Multiscale materials modelling" and related post 2 _ "Universal size/shape-dependent law for characteristic temperatures, phase transformation in nanoparticles," I decided to go back to basics.
It is widely known in the nanotechnology field, and as previously mentioned in my earlier post (2) that the ratio of surface area to volume increases as the size of particles size decreases (roughly as the inverse ratio of the characteristic dimension (x). cf graphs above where r is taken for spherical shapes and L for cubic shapes). At small nanosizes this increase in surface is quite dramatic. This surface to volume relationship is the most basic engineering factor in nanoscience and technology. It underpins the surface dependency of most if not all nanoscience and technology fields, eg. where surface properties and effects at low weight are required such as in catalysis or in fuel-cell applications to mention only two.
Numerous works mostly from teaching nanomaterials sources approach the subject but the best to my mind is the work by Mike Ashby et al in their book "Nanomaterials, nanotechnologies and design: an introduction for engineers ..." By M. F. Ashby, Daniel L. Schodek, Paulo J. S. G. Ferreira (ref. 1, and relevent pages in the google embedded book, read it below ) (*Prof Mike Ashby, FRS, is famous for his ability to reduce complex engineering materials mechanical properties to their simplest expression and to describe them comparitively in his now well-known Ashby diagrammes. This lead Mike to create Grant Design Ltd., in 1994 with Dr D.Cebon both of Cambridge Univ., UK. cf. Related posts )
Not to give Mike a full clean slate,(although most deserved) I have checked, re-calculated and presented Ashby et al's results in the above graphs using the fairly intuitive Wolfram Alpha's Mathamatical Tool.
To get a better grip on nano-things, their book Ch 6.2 also gives a simple numerical example of the number of increasing number of particle when reducing a particle size from 10µm diametre to a group of 10 nm in diametre particle of identical total volume. (N=V10µ/V10nm). This 10nm group is shown to be comprised of 10^9 particles which in turn is shown to to give a 1000 times increase in surface area. (notice the unit 10 is diametre and not radius)
The graph below right follows Ashby et al's eqn. 6.9
cf. embedded book pages below
Next, the authors treat crystalline nanoparticles. They point out that in addition to shape, structure must be taken into account.
There is a brave attempt to show how we get to the above equation by Univ of Wisconsin, Chem 801 Lecture notes (ref 2 below).
No wonder as a student I started to see modulable atomic structures (lego like principle), in the chemistry professors offices or on the lecture hall benches!)
Now thermodynamics imposes a total energy minimisation. For the FCC nanoparticle this given by (surface area X the surface energy), neglecting edge and curvature effects. They present an arguement based on atomic planes of high symmetry; Amoung possible shapes the smallest FCC nanoparticle is the cubo-octohedron. (Ashby fig. 6.20) which is a 14 sided polyhedron (looks almost spherical, doesn't it.) consisting of 12 surface atoms and one bulk atom.

Total nos of surface atoms Ns= 10n2-20n+12 (eqn 6.13 Ashby)
More about this book
To get the most out of this book via author authorized limited preview, the reader will find my blog format too small, so take a squint to judge your degree of interest, but whatever, do check the full sized version by clicking the button "More about this book" on the bottom right hand (RH) corner of my embeded version, it's free. A new page opens which allows you to enlarge to suit any level of reading capacity. You can do your own review there and please leave a comment either on the subject of my post or on any of the themes available in the preview. Thanks in advance
RELATED POSTS:
Multiscale modelling of materials,MMM - Introduction and Explanatory Notes; Refs.,Images, on a Hot Interdisciplinary field
REFERENCES.
1."Nanomaterials, nanotechnologies and design: an introduction for engineers ..." By M. F. Ashby, Daniel L. Schodek, Paulo J. S. G. Ferreira CH 6 Size effects Surface to volume ratio versus Shape.
2. Chem 801 Lecture Notes, Univ of Wisconsin
and first experience with Wolfram Alpha. Both postive, a pleasure.
Having "dived in at the deep end" on a couple of recent posts, only just managing to "scratch the surface" in related post 1_ "Multiscale materials modelling" and related post 2 _ "Universal size/shape-dependent law for characteristic temperatures, phase transformation in nanoparticles," I decided to go back to basics.It is widely known in the nanotechnology field, and as previously mentioned in my earlier post (2) that the ratio of surface area to volume increases as the size of particles size decreases (roughly as the inverse ratio of the characteristic dimension (x). cf graphs above where r is taken for spherical shapes and L for cubic shapes). At small nanosizes this increase in surface is quite dramatic. This surface to volume relationship is the most basic engineering factor in nanoscience and technology. It underpins the surface dependency of most if not all nanoscience and technology fields, eg. where surface properties and effects at low weight are required such as in catalysis or in fuel-cell applications to mention only two.
Numerous works mostly from teaching nanomaterials sources approach the subject but the best to my mind is the work by Mike Ashby et al in their book "Nanomaterials, nanotechnologies and design: an introduction for engineers ..." By M. F. Ashby, Daniel L. Schodek, Paulo J. S. G. Ferreira (ref. 1, and relevent pages in the google embedded book, read it below ) (*Prof Mike Ashby, FRS, is famous for his ability to reduce complex engineering materials mechanical properties to their simplest expression and to describe them comparitively in his now well-known Ashby diagrammes. This lead Mike to create Grant Design Ltd., in 1994 with Dr D.Cebon both of Cambridge Univ., UK. cf. Related posts )
Not to give Mike a full clean slate,(although most deserved) I have checked, re-calculated and presented Ashby et al's results in the above graphs using the fairly intuitive Wolfram Alpha's Mathamatical Tool.
To get a better grip on nano-things, their book Ch 6.2 also gives a simple numerical example of the number of increasing number of particle when reducing a particle size from 10µm diametre to a group of 10 nm in diametre particle of identical total volume. (N=V10µ/V10nm). This 10nm group is shown to be comprised of 10^9 particles which in turn is shown to to give a 1000 times increase in surface area. (notice the unit 10 is diametre and not radius)
The graph below right follows Ashby et al's eqn. 6.9
cf. embedded book pages belowNext, the authors treat crystalline nanoparticles. They point out that in addition to shape, structure must be taken into account.
They chose a nanoparticle with a the face centered cubic (FCC) structure, due to its practical importance, eg. Au, Ag, Ni, Al,Cu,Pt have FCC structure. The FCC unit cell, has 14 atoms all on the surface.(cf. image in EB below, ) The general equations for increasing numbers of atoms (n) by increasing unit cell layers are given as:
Total Nos of Surf Atoms Ns=12n^2+2 (eqn 6.10, Ashby et al EB)
Total Nos of Bulk Atoms Nb=4n^3-6n^2+3n-1 (eqn 6.11 Ashbey et al EB)
With (n) as input, resultats are tabulated for n, Ns, Nb, Ns/Nb ratio and percent. in table 6.1 of the EB below and are the so called "structural magic numbers".
There is a brave attempt to show how we get to the above equation by Univ of Wisconsin, Chem 801 Lecture notes (ref 2 below).
No wonder as a student I started to see modulable atomic structures (lego like principle), in the chemistry professors offices or on the lecture hall benches!)
Now thermodynamics imposes a total energy minimisation. For the FCC nanoparticle this given by (surface area X the surface energy), neglecting edge and curvature effects. They present an arguement based on atomic planes of high symmetry; Amoung possible shapes the smallest FCC nanoparticle is the cubo-octohedron. (Ashby fig. 6.20) which is a 14 sided polyhedron (looks almost spherical, doesn't it.) consisting of 12 surface atoms and one bulk atom.
For the cubo-octoherdral nanopartical, the crystal structure is maintained and the eqns giving the structural magic numbers are:

Total nos of surface atoms Ns= 10n2-20n+12 (eqn 6.13 Ashby)
Total nos of bulk atoms Nb= 1/3(10n^3 - 15n^2 + 11n - 3) (eqn 6.13 Ashby)
I have ploted the ratio Ns/Nb from the above eqns with hints on the ease and flexability of wolfram's maths tool. Trial and error is a good guide in this easy to use tool. Enough...
There is more and better in this my first Embedded Google Book.
It is with immense pleasure and priviledge that I am able to present "Nanomaterials, nanotechnologies and design: an introduction for engineers ..." By M. F. Ashby, Daniel L. Schodek, Paulo J. S. G. Ferreira.
More about this book
To get the most out of this book via author authorized limited preview, the reader will find my blog format too small, so take a squint to judge your degree of interest, but whatever, do check the full sized version by clicking the button "More about this book" on the bottom right hand (RH) corner of my embeded version, it's free. A new page opens which allows you to enlarge to suit any level of reading capacity. You can do your own review there and please leave a comment either on the subject of my post or on any of the themes available in the preview. Thanks in advance
Peruse with pleasure and make your own judgement.
RELATED POSTS:
Multiscale modelling of materials,MMM - Introduction and Explanatory Notes; Refs.,Images, on a Hot Interdisciplinary field
Universal size/shape-dependent law for characteristic temperatures, phase transformation in nanoparticles
Ashby Diagrammes, Granta Design, Materials selection software
It's not HSLA-Bainite"Nanostructured Steels"-Green Light by Irvine-based Materials Science Co-MMFX Tech Corp - Corrosion and Toughness Themes
REFERENCES.
1."Nanomaterials, nanotechnologies and design: an introduction for engineers ..." By M. F. Ashby, Daniel L. Schodek, Paulo J. S. G. Ferreira CH 6 Size effects Surface to volume ratio versus Shape.
2. Chem 801 Lecture Notes, Univ of Wisconsin
Thursday, 2 October 2008
A materials science community must for professionals & students: Nanotechnology Timeline, Past & Future & the Top Ten
The Nanotechnology View: Timeline, Info. List and Map from Google’s experimental labs. R& D to Market – looks very good.And for every man, woman and student – a lifelong learning tool?
Some of the more specialised, or more motivated, readers may have followed my two previous posts on the "Metallurgical & Materials Science Revival" entitled -"Up for review". Ten Top exciting new fields were earmarked by P. Ball of Nature, for a promising and health future.
The Top Ten are for memory: 1-Photonic materials, 2 -New types of magnetic memory materials, 3-Smart materials, 4 -Biomaterials and bio-mimicry, 5 -Biomedical materials, 6 -Energy Materials, 7 -Nanoporous materials-surface active-catalysts 8 -Diamond and hard surface materials, 9 -Functional polymer science 10 -Surface and interface science, measurement and imagery critical in the development of new materials.
Nanotechnology is a horizontal technology. It spans several, and often many fields.
An imaginative, innovating tool "par excellence".
Google's experimental lab's Timeline View may prove a most useful tool to help review and the Ten Top New Fields listed in the previous post:
-The time line takes a look at past statistics, gives chronological data, people and web sites, and future projections.
-Info lists gives main sites, online publishers, up and coming companies, quality sites with a key-button top right- to dates, measurements, locations and images. All you need for a rapid overview of the field and images to please the most exigent web publishers and web-loggers.
-List view is a classic search list.
-Map view is a great way to get to know your “customers” find –out “who’s who & more so “where’s where” Labs,Univ. Co’s . This will keep our geography up to date!
Unless specified, the map view opens on US locations – it’s a great alternative to the election state maps – and the McCann vs Obama electoral and cash battle, although you may wish to superpose both “before & after.”
For a view UK players just type UK in the search box right tab.
For a view of European Union players I typed France and ran through the list – the main EU players are there.
The user can also of course, use the now familiar Google navigator ladder N-S, E-W and take a world tour.
For South America, Africa and Middle East, Asia, Russia same procedure
Readers of course will see all sorts of applications to "make life easier" both professionally and personally. Now for those who followed my two posts on the "Metallurgical & Materials Science Revival" exciting new fields earmark by P. Ball of Nature, may see uses for such tool
There are more themes available. Cf.below:
SOURCES and LINKS:
Source and Link to the Nanotechnology Timeline View.
More available themes -LINK
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