Downloaded 207 times
Uploaded byRakesh Khandal
Nano kolkata
This document discusses nanomaterials and their applications. It begins by defining nanomaterials as materials consisting of particles sized in the nanometer range. Nanomaterials are then classified based on their dimensions as 0D, 1D, 2D or 3D materials. Unique properties emerge at the nanoscale, including improved mechanical, thermal, magnetic, and optical properties compared to bulk materials. Examples of applications discussed include uses in energy conversion, self-cleaning coatings, and camouflaging. The document also outlines Shriram Institute's experiences developing nanomaterials for optical applications and effluent treatment.
More Related Content
Nano kolkata
- 1. NANOMATERIALS FOR ADVANCED APPLICATIONS SHRIRAMINSTITUTE FOR INDUSTRIAL RESEARCH 19, UNIVERSITY ROAD, DELHI-110 007 Email : sridlhi@vsnl.com Website : www.shriraminstitute.org Presented by : Dr. R.K. KHANDAL
- 2. Outline Materials Nanomaterials Nanomaterials Applications ofNanomaterials Experiences of SRI Properties Domain Process Dimensions Challenges Properties Definition Classification Features
- 3. Classification of Materials(Type & Structure) Composites Ceramics Polymeric Crystalline Polycrystalline Amorphous Metallic Electronic Biomaterials Nanomaterials Nanomaterials include all classes of materials at the nanoscale Nanomaterials are categorized as 0-D (nanoparticles),1-D (nanowires, nanotubes, nanorods), 2-D (nanofilms, nanocoatings), 3-D (bulk)
- 4. Properties of Materials: Critical Factors (Bulk Vs Nano) DefectsDefects + Mechanical Optical Thermal Magnetic At the nanoscale, interactions with heat ,light, stress, electrical field & magnetic field give rise to interesting & novel properties A thorough understanding of the nature of interactions at the bulk & nano levels are essential for designing nanomaterials InternalInternal StructureStructure Bulk (Macro & micro) Nano SizeSize ShapeShape Surface area toSurface area to Volume ratioVolume ratio + +
- 5. Nanomaterials: Materials consisting ofparticles of the size of nanometer Volume = Surface Area * Thickness For a given volume: Surface area Thickness More atoms at surface than in the interior Extraordinary activity SCOPE: DEFINITION
- 6. SCOPE : DOMAIN KeywordsDomain Particle size Distribution in the continuous phase Modification of surfaces Interfacial tension Surfaces Interfaces Rising volume fraction Homogeneity of phases of dispersing phase Domain of Nanotechnology: Multi-phase systems Liquid : Liquid Solid : Liquid Surfaces and interfaces involving different phases Gas : Liquid Gas : Solid
- 7. Systems Process Emulsion MacroMicro Dispersion Coarse Fine Solution Colloid SCOPE: PROCESS A process to create a continuous dispersed phase as fine as possible for homogeneity with the dispersing phase (Liquid / Liquid; Gas/Liquid) (Solid / Liquid) (Solid / Liquid; Liquid/Liquid) Solubilization
- 8. SCOPE : DIMENSIONS WhatHappens Dimensions Particle size More from less Surface area Enhanced coverage Activity Novel products Efficiency Improved performance per unit mass Maximum possible benefits from minimum possible inputs Effecting changes through and at atomic scale
- 9. Nanomaterials: Features Synergistic combinationsof materials of different kinds & characteristics is possible through nanotechnology Coatings, Films Surface modificationSize Reduction 10 nm 1 µm 1 cm CompatibilityHuge interfaces Solid Liquid Homogeneous solution Inorganic nanoparticles in a liquid media +
- 10. Process of makingNanomaterials Process steps Inputs Macro Micro Nano Challenges: Process Technology Challenge: To have a process that can convert macro materials into nanomaterials spontaneously & with minimum efforts Energy Bulk Sugar cube Nano Dissolved sugar/salt Bulk Output Salt
- 11. Multi-phase systems: Approach Ability to design materials with tunable properties In-situ way of production of nanomaterials leads to more homogeneous matrix with higher loading of nanoparticles Physical Ball milling Gas condensation E-beam evaporation Vapour deposition Sputtering Chemical Microemulsion Sol-gel Chemical reduction Ex-situ In-situ •Bulk production •Reproducibility •Stability •Cost • Single step • Non-agglomeration • Better Stability • Interfacial interaction Hydration Hydrolysis Solubilization Chemical conversion Precipitation Concerns Benefits
- 12. Synthesis of Nanomaterials:Ex-situ TiO2 TiO2 - - - - - - TiO2 TiO2 - - - - - - MonomerPolymer Surfactant - -Radical Polymerization 10 nm 100 µm Grinding Latex Fe2O3-Particles Fe2O3-Particles Latex bead Pre-treatment Polymerization Copolymer layer Encapsulated particle Amphiphilic molecule Monomer Ex-situ synthesis of nanomaterials involves number of steps Polymer encapsulated nanomaterials used for targeted delivery of drugs- good example of ex-situ synthesis
- 13. Synthesis of Nanomaterials: In-situ Metal salt + Monomer Adopting in-situ approach of synthesizing nanomaterials reduces number of steps involved and hence simple process ! Nanocomposite 1. Hydrolysis 2. Polymerization
- 14. Designing Nanomaterials :Approaches Metal Ceramic Polymer Matrix Reinforcing phase Inorganic Metals & inorganic Metals Examples Carbides, borides, nitrides, oxides, etc. SiC, Zr, Fe, W, Mb, Ni, Cu, Co, etc. C nanotubes, alumina, silica, etc. Nanocomposites have tremendous scope in all areas of science & technology.
- 15. 0 - D 1- D 2 - D Dimension Thermal conductivity is more prominent in 1-D & 2-D nanomaterials Thermal conductivity of C nanotubes (2-D nanomaterial) = 3000 Wm-1 K-1 ; Copper (bulk) = 400 Wm-1 K-1 Structure of Nanomaterials: Size and Shape 3 - D Bulk x , y , z Nanocomposite thick film Rods Tubes Wires d=100 nm d 100 nm Example Nanoparticles Nanofilms Nanocoatings Application Bottle-neck Waveguides Components for PC, Mobile phones x , y x Nil Direction of confinement
- 16. Unique Properties ofNanomaterials Nano-sizeBulkProperties Thermal • S / V • Heat transport Small Electrons Large Phonons Unique properties at the nanoscale have led to the use of nanomaterials in fields where conventional materials have limitations Magnetic Optical • Super- paramagnetism Absent Prominent • Absorption • Emission • Reflection Bulk effects Material dependent Surface Plasmon effects Size dependent
- 17.
- 18. Transportation of Heat:Nanomaterials Mechanism of heat travel : Electrons (metals) & Phonons (non-metals) λ Phonons ≈ L nanostructure; λ Phonons < L macrostructure When size of the material is reduced to nanoscale, quantum confinement occurs Confinement at nanoscale occurs in 0-D (x, y, z directions), 1-D (x,y directions), 2-D (x direction) and 3-D (bulk) Quantum confinement effects ~ electron transport mechanism of bulk materials
- 19. Pt bulk Pt 28nm Pt 15 nm λ0(W/mK) T0 (K) Properties of Nanomaterials : Thermal Conductivity Separate 2 crystals of same materials with different orientations (grain boundary) Separate 2 crystals of different materials (multilayer structure; different densities & sound velocities) Phonon scattering at the interface Interface In nanosystems, there is presence of huge interfaces Interfaces Thermal resistance Phonon scattering Thermal conductivity Films
- 20.
- 21. Magnetism in Nanomaterials Strongcoupling Critical particle size : below which material will be in single domain; hence magnetism If particle size is << critical diameter, loss of magnetization occurs; super-paramagnetism Interaction energy is effective at sizes less than critical diameter but above super-paramagnetism Critical diameter of Co = 70 nm & Fe = 15 nm Small size of particles Features Consequence Dominance of exchange forces Alignment of spins
- 22. Hc D sp Dcrit Single Domain Multi- Domain Magnetic Properties Coercive field of Ferromagnetic materials with particle size Particle size < Dcrit Single domain Magnetization Particle size <<< Dcrit Super-paramagnetism
- 23.
- 24. Optical effects:Metamaterials η =√µrεr Most promising area of application : Metamaterials Size, shape & composition of embedded nanoparticles influence the interactions with light, heat ,sound & waves etc 1 2 1 2 +ve R.I. -ve R.I. Refractive Index η =√µrεr µr: Permeability to magnetic field εr: Permeability to electric field • µr, εr= -ve • Induced phenomena µr, εr= +ve Natural phenomena
- 25.
- 26. SOLAR SPECTRUM Visible light (43%) X-raysMicro wave Radio wave Infra red radiation (54%) UV (3%) Long Wavelength 1012 nm106 nm700 nm Chemical changes : Bond Dissociation Bond Formation Rearrangement Electron transfer The energy of electron 1.23 eV ≅ λ1000nm; thus, energies corresponding to λ < 1000nm can bring about chemical changes. The region from 200nm to 1000nm is most useful for photochemical conversion. Lux 400 nm 109 nm 1014 nmWavelength,λ Short Wavelength 200 nm
- 27. SOLAR SELECTIVITY :MATERIALS RESPONSE Frequency (Hz) Visible Infrared Ultraviolet X-rays Cosmicrays 1081010 101210141016 1018 10201022 Radiofrequency Gammarays Microwave High Potential for harnessing the solar energy Processes involved Inner electronic transition Outer electronic transition Molecular Vibrations Molecular rotations vibrations Electron spin resonance Nuclear magnetic resonance Change at atomic & molecular levels can become the via media for harnessing solar energy. Solar sensitive materials undergo region specific transition Solar energy conversion
- 28. PHOTOCHEMICAL CONVERSION :MECHANISM The Energy E of single photon is given by the Planck equation:- E=hν= hc/ λ Sun light . …….. ...………………………………electron Excitation photon excited state Non-radiative relaxation Conduction band Valence band h+ e- Band gap E=hν Every photochemical conversion process requires as an initial steps the absorption of photon energy and conversion into the internal energy of the first excited state of the molecule of the material φ = Number of events Number of photons absorbed …………………… …………
- 29.
- 30. The play oflight on a butterfly’s wings has inspired designing of novel photonic materials for solar cells, photovoltaics, camouflaging, optical fibers and military applications Invisibility cloak Color play Tailor-making of refractive index and dielectric constant Nanomaterials : Camouflaging
- 31. Nanomaterials: Photochemical Conversion Advantages Utilization of unabsorbed part of solar spectrum Reduced heat dissipation Quantum Dots 100 nm50 nm Reactivity 10 nmSize (nm) Nanotubes & nanowires Mesoporous
- 32. MATERIALS FOR ENERGYCONVERSION : SEMICONDUCTORS Challenge is maneuver the band gap:make it sensitive to visible light. 6.3 eV 3.15 eV 1.58 eV U.V 200 nm 400 nm 800 nm Visible TiO2 ZnO CdS WO3 Band gap Energy EMS(λ) TiO2 = 3.20 eV ZnO = 3.35 eV WO3 = 2.80 eV CdS = 2.42 eV Semiconductors are the most ideal and preferred materials.
- 33. Nanomaterials: Self-Cleaning Hydrophobic Photocatalytic Designingof materials with novel effects like hydrophobic, hydrophilic, photocatalytic, etc. has made possible new applications like self cleaning, coatings, etc. Coating Dirt run- off Light Coating Roll-off effect
- 34. Nano materials 101 Ti alloys Brass Mildsteel Al alloys Copper Lead PE, PA PP, ABS PS, PET PVC Alumina Zirconia Glass Concrete Bricks Metals Polymers Ceramics Ideal Strength High Strength Building MaterialsYieldStrength(σy)/Young’sModulus(E) 10-4 10-3 10-2 10-1 Bulk materials fall short of the ideal values in every aspect; mechanical, optical, electronic, magnetic, thermal, etc. Nanostructure, nanolayers & amorphous materials are strongest
- 35. Density (Mg/m3 ) Foams Natural materials Polymer nano- composites Polymers Metals Metallic nanocomposites Nanocrystalline metals Ceramics Standard composites Nanotubes& fibers Young’sModulus(GPa) Elastomers Ceramic nanocomposites 0. 1 1.0 10 10-4 1 10 100 10-3 1000 High Strength Materials: Smart Materials
- 36. Foams Natural materials Polymer CNT composites Polymers & Elastomers Metals Metallic nanocom- posites Nanocrys-tallin metals Ceramics Standard composites Nanowires (Cu,Ag, Au) TensileStrength(MPa) Density (Mg/m3 ) 0. 1 1.0 10 100 0.1 10 100 104 1 105 Polymer-Ceramic nanocomposites 3-D ceramic nanoco- mposite 1-D metallic nanostructures 1-D C-nanostructures 103 Engineering Nanomaterials Nanomaterials
- 37. Green Materials :Nanoengineered Concrete Nanosilica Precipitated Silica Silica fume Metakaolin Finely ground mineral additives Portland cement Fly ash Aggregate fines Natural sand Coarse aggregates Nano engineered concrete High strength/ high performance concrete Conventional concrete 100 101 102 103 104 105 106 108 107 10-1 10-2 100 101 102 103 104 105 106 Particle size(nm) SpecificSurfaceArea(Kg/m2 ) Nanoparticles allow better void filling & positive filler effects & improved bond between pastes aggregates; nanosized additives increase strength beyond what is attained with conventional materials
- 38. SRI’S EXPERIENCE SRI hasdeveloped nanomaterials for : Optical applications Effluent treatment
- 39. 39393939393939 High Refractive IndexMaterials The refractive index of low refractive index materials increases from 1.49 to 1.66. 1.41 1.47 1.53 1.59 1.65 1.71 0 10 20 30 40 50 60 70 80 90 100 % of additive Refractiveindex
- 40. 40404040 Refractive index increaseswith increase in percentage of metal salt. 1.41 1.42 1.43 1.44 1.45 1.46 1.47 1.48 0 5 10 15 20 25 30 Metal salt (% by wt) RefractiveIndex Barium Hydroxide Lead Monoxide Lanthanum Oxide High Refractive Index Acrylates
- 41. 414141414141 High Refractive IndexTitanium Nanocomposites In-situ formation of nanoparticles of Ti The refractive index of the polymer increases from 1.45 to 1.53 1.44 1.46 1.48 1.5 1.52 1.54 0 2 4 6 % Ti RefractiveIndex
- 42. Photocatalytic Material :Doped TiO2 XRD analysis confirms the doping of TiO2 Change in lattice parameter ‘a’ & ‘c’ of TiO2,confirms the incorporation of Cd2+ in Ti4+ Influence TiO2 Doped TiO2 Doped TiO2 factor (In-situ) (External) a/nm 3.0301 3.3184 3.3558 c/nm 9.5726 10.0136 11.2138 Intensity(a.u.) Position (2 Theta) 20 30 40 50 60 70 80 External In-Situ method TiO2 market procured TiO2 (Reference)
- 43. 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 200 300 400500 600 700 800 Wavelength Absorbance MG A B C Semiconductors are used to prepare nanocomposites with enhanced photocatalytic activity Dye Nanocomposites & dye degradation
- 44. Nanocomposites lead tocomplete degradation of dye Useful for the treatment of dye effluents 91.29 92.30 94.49 37.29 86.61 87.19 0 20 40 60 80 100 A B C Degradationrate(%) Nano Normal Nanocomposites for dye degradation
- 45. Dye solution Nanocomposite Dye removal Swellednanocomposite after uptake of dye Dye removal from effluent Nanocomposites for Effluent Treatment
- 46.