self organization of nanostructured materials
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TRANSCRIPT
SELF ORGANIZATION OF NANOSTRUCTURED MATERIALS
Presented by
Najiya KPP
INTRODUCTION SELF ORGANIZATION KINDS OF SELF ORGANIZATION MICELLE,LIPID BILAYER EPITAXIAL GROWTH SELF ORGANIZATION OF NANOSTRUCTURES
ON INTERLAYER SURFACES CONCLUSION
OVERVIEW
Self-organization occurs in a variety of physical, chemical, biological, and cognitive systems.
Common examples are crystallization of snow, cloud formations, Chemical reactions leading to dissipative structures, Growth of plants and animals etc
INTRODUCTION
This example shows the formation of crystals, such as the snowflake
Are there general principles for self-organization?
Self Organization Process of formation of ordered nanostructures
using atoms as small building blocks without any external energy.
Some form of global order or coordination arises out of the local interactions between the components of an initially disordered system.
This process is spontaneous: it is not directed or controlled by any agent or subsystem inside or outside of the system; however, the laws followed by the process and its initial conditions may have been chosen or caused by an agent.
Principle – Bottom up approach
Pattern formation in a chemical reaction (Belousov-Zhabotinsky reaction)
The formation of a great variety of patterns on sea shells
ordered arrays of core shell nanoparticles
By self-organization, individual molecules are built-up and integrated into larger units and hierarchical structures with unique functionalities.
Natural systems become structured by their own internal processes – self
organizing systems
Different nano-morphologies such as quantum dots, formation of
nanowires, nanotubes etc are possible by self organization.
SELF ORGANIZATION
Thermodynamically stable nanostructures-- Micelle
-- Lipid bilayer
Kinetically self organized
-- Molecular beam epitaxy
KINDS OF SELF ORGANIZATION
Aggregate of surfactant molecule dispersed in a liquid colloid.
Micelles are organized molecular assemblies of surfactants.
--Reverse micelle (water in oil)
--Normal micelle (oil in water)
MICELLE FORMATION
Scheme of a micelle formed by phospholipids in an aqueous solution
Micelles are formed when
- concentration of the surfactant greater than Critical
Micelle Concentration(CMC)
-temperature of the system greater than Kraffts Temperature Size and shape of micelle depends on surfactant
concentration.temperature,pH etc
Micelles in Medicine
self-forming micelles by an eczema drug
LIPID BILAYER
Biological membranes are composed of Lipid bilayer
Lipid bilayer is a universal component of all cell membranes.
The structure is called a "lipid bilayer" because it composed of two layers of fatty acids organized in two sheets.
They are formed in sheet-like structures that contain both a hydrophilic and a hydrophobic moiety.
The hydrophobic interactions among several phospholipids and glycolipids-a certain structure called lipid bilayer or bimolecular sheet is favored. A bilayer lipid membrane
Lipid Bilayer
Cone-shaped lipid molecules for micelles, cylinder-shaped lipids form bilayers
Packing arrangements of lipid molecules in an aqueous environment
MOLECULAR BEAM EPITAXY
Molecular vapor deposition of a crystal is achieved using an epitaxial reactor, called Molecular beam epitaxy
Ultra-High-Vacuum based technique for producing epitaxial structures with monolayer control
Epitaxial - growing crystalline layers on a cyrstalline substrate
Used in the construction of quantum wells, dots and wires for use in lasers
MBE System
Vacuum System Liquid N2 cryopanels Effusion Cells Substrate Manipulator
The Growth Process 3 Phases:
• Crystalline phase of the growing substrate
• Disordered gas phase of the molecular
beams
• Near-surface transition layer between the
crystalline and gas phases
desorption
islands
diffusion
nucleation
deposition
downward diffusion
edge diffusion
SURFACE PROCESSES
Formation of arrays of interlayer nanostructures in layered crystals
Sb2Te3 and Bi2Te3 layers are shown to contain step layered structures with nanostructured islands on them
Cu is incorporated into the layers Bi2Te3 as into nanocontainers, without interacting with excess components of Bi2Te3.Te–Te spaces in Bi2Te3 act as nanocontainers for copper.
Particles execute Brownian motion in Te–Te spaces along the Bi2Te3 Cu ⟨ ⟩surface and merge upon the first collision.
Nanocell formation begins during impurity diffusion along the basal plane and whisker growth on the surface at Te vacancies in the same telluride fivelayer slabs.
The spontaneous diffusion into layers can be termed self intercalation and considered evidence of selforganization.
Fig. 1. (a) 3D and (b) 2D AFM images of fractal surfaces in Bi2Te3 Cu⟨ ⟩
Fig 2. Schematic of the arrangement of bismuth and tellurium atoms in the structure of Bi2Te3 and model concepts for selforganization of processes in the layers: (а) incorporation of atoms along the (0001) plane, (b) formation ofa new island, (b, d) diffusion of particles, (c) aggregation,(e) diffusion of the island.
Currently,much effort has been undertaken to develop an effective and technologically simple method used for the synthesis of nanostructures over a macroscopic surface area.
Today, the research spotlight is especially focused on self-organized nanostructured materials
Self organization can be utilized as an efficient synthetic route for the construction of nanometre-scale architectures
Self organization research explodes drawing the interest of researchers from every imaginable field.
CONCLUSION
Nanostructured materials- basic concepts and microstructures - H. GLEITER,Forschungszentrum Karlsruhe, Institute of Nanotechnology, D-76021 Karlsruhe, Germany
Epitaxial self-organization: from surfaces to magnetic materials-Olivier Fruchart Laboratoire Louis Néel (CNRS), 25, avenue des Martyrs, BP166, 38042 Grenoble cedex 9, France
Growth and SelfOrganization of Nanostructures on Interlayer Surfaces of A2B3 Layered Crystals - A. N. Georgobiania, A. M. Pashaevb, B. G. Tagievb, F. K. Aleskerovc, O. B. Tagievd, and K. Sh. Kakhramanovc
http://www.scholarpedia.org/article/Self-organization http://www.chemie.uni-hamburg.de/pc/klinke/publications/Press-
release-english.pdf http://www.sciencedirect.com
REFERENCES
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