Outline Nanoengineering — • I. General introduction Toward Controlled Creation of New − Our interests and facilities in nanomaterials − Nanoengineering Inorganic and Nanomaterial • II. Chemical engineering of nanoparticles Architectures and material nanostructures − Liquid phase synthesis − Processing by external fields • III. “Molecular engineering” of Michael Z. Hu nanostructures − Arrays of inorganic nanochannels/nanotubes: Oak Ridge National Laboratory orientation/ordering control [email protected] − Space-confined self-assembly: nanostructure 800oC 700oC 500oC σ ZrO :1 0 % Y O 2 s 2 2 3 0.52eV e p ita x ia l film o n M g O - su b stra te σ in te rfa ce 1 control within inorganic nanowires surface/interface diffusion 0 0.93eV con tro lled (p red icted) σ σ bulk σ -1 b nanocrystallinenanocrystalline film d = 20nm 865-574-8782 g 1.04eV -2 bulk diffusion Log conductivity (S/cm) Log conductivity controlled -3 data for single Y SZ crystal & film s d > 60nm • IV. Potential applications 910111213 104 /T (K -1 ) − Fuel cells, solar cells, sensors, … • V. Concluding remarks OAK RIDGE NATIONAL LABORATORY OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY U. S. DEPARTMENT OF ENERGY ORNL Is A World Leader in Nanosciences and Nation’s Premier Facilities in Advanced Materials Materials Research Nanoengineering Lab • Center for Nanophase Materials Sciences SNS (CNMS) Neutron & synchrotron sources • Spallation Neutron CNMS Source (SNS) & High DOE’s first nanoscience center Flux Isotope Reactor (HFIR) scattering facilities • High-Temperature Ultrascale computing Materials Laboratory HTML facilities Facilities (HTML) • (NEW!) Center for Radiation Detection Materials and Systems (CRDMS) OAK RIDGE NATIONAL LABORATORY Advanced Electronic Microscopy U. S. DEPARTMENT OF ENERGY Engineering vs. Science Our Interests: Develop “NanoEngineering” for Controlled Nanosize & Nanostructure • Definition (per Webster’s): − Science: “… a branch of knowledge or study dealing with a body of facts or truths • Chemical Processes systematically arranged and showing the (including biomimetic processes) Process Engineering operation of general laws … systematic knowledge of the physical or material world − “Bottom-up” in nature, using At Nanoscale …” molecules and particles as building-block precursors Scalable processing (beyond today’s − Engineering: “… the art or science of making − Suitable for large-scale with nanoscale nanosciences and practical application of the knowledge of pure production economically process control engineerings) sciences, as physics, chemistry, biology, etc. …” • Engineered Chemical Controlled or Large-Scale Processing of Nanomaterials Formation/Assembly of − Nanoengineering: ??? – a new paradigm Designed Nanostructure ¾ Must be enabling, not just the traditional NanoTechnology shall go − Nanoscale chemical reaction scale-up problem beyond NanoScience ! (chemical engineering) ¾ Beyond existing engineering: chemical - Process scale − Molecular engineering engineering, materials engineering, etc. - Level of precision of process (chemistry + molecular design ¾ Need a transition from nanoscale science control + self-assembly + process to nanoengineering - Production through-put rate engineering) Controlled - Dimension of products − Interface engineering Properties/Functions OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY Nucleation and Growth and Self-Assembly Molecular Design and Process Engineering Are Enabling Approaches to “Build Up” Control the Growth of Nanostructure Advanced Nanomaterials examples of fundamental building blocks “Controlled” build-up (growth) • Allow bottom-up manufacturing of nanophase/particles/nanopores • A world of inorganic materials can be made by controlled Homogeneous Heterogeneous “living growth” “living growth” Tailored nanostructures Particle Film/Interface in advanced materials Porous inorganics Size & distribution Uniformity Engineered manufacturing of Nanopore size Shape Positioned surface growth advanced ceramics/composites Shape Crystallinity Nanophase grain size could impact various applications Orientation Surface chemistry Surface roughness 1 nm Domain scale ¾Energy storage and conversion Pore structure Crystal structure Nanoparticles, Films, Coatings, Nano-, Meso- Nanorod,wires (fuel cells, solar cells) Core-shell Patterned film Nanocrystals Membranes Porous Materials Nanocomposites ¾Separations (inorganic membranes) Colloidal crystal Film porosity Linked network Multilayer ¾Catalysis ¾Micro-/nano-electronics ¾Sensors, detectors, devices Chemical process understanding and control must be obtained to 1-dimensional Nanocrystalline Nanoscale Chemical process understanding and control must be obtained to ¾Targeted therapy, drug delivery, Nanowires, Fibers Dense Ceramics Patterned Film achieve nanoscale engineered build-up of materials etc. We Focus on Real-Time Process Monitoring and Control to Example: SAXS Monitoring of Sol-Gel Processing of understand & develop engineering processes for Nanomaterials in Solutions manufacturing nanomaterials We have developed capability for studying early stages (as short as 80 ms). • Small-Angle Scattering (SAXS and SANS) • Dynamic Light Scattering (DLS) SAXS from Early-Stage Zr-Nanoclusters (0.2 – 200 nm length scale for SAXS) (5 – 1000 nm nanosize range) Thermostatically Controlled Laser Power Enclosure Alcohol+ Alcohol+ Porod plot Supply Acid+H2O Alkoxide Incident Beam Sample Cell He-Ne Laser Tube Mixing Scattered Light Tubing with adjustable length Photomultiplier Tube D = 1.8 → 2.4 Sample f Computer-Interfaced (weakly to strongly branched w/ a Power X-Ray Chamber consistent length of 8.3 + 0.5 & ) Digital Auto Correlator Supply (1-mm capillary Detector MCA 2 2 2 (BI 9000-AT) Source cell with 10-µm I(Q) = Ie(Q)Np(Δρν) exp (-Q Rg /3) Or FTIR thick wall) • In-situ, high-temperature XRD (HTXRD) Mass fractal scattering model Scattering is Computer I(q) = NP(q) S(q) complementary to N = number density Waste electron Form factor (for spherical particles): 2 2 2 3 2 microscopy P(q) = V (Δρ) {3[sin(qr0) - qr0cos(qr0) ]/(qr0) } D HTML facility HRTEM A “Steady-State” Technique Based on Structure factor: S(q) = [1+1/(qr0) f DfΓ(Df-1)sin[(Df - 1)arctan(qξ)/[1+ 1/(q2 ξ2)](D -1)/2 offer existing Rapid Mixing Flow-Cell f capability J. Mater. Sci., 35, 1957 (2000). J. Non-Crystal. Solid, 246, 197 (1999). Example: Engineered Processes Need to be Developed for Outline Novel DTS Processing of Monodispersed Oxides Highlight of Dielectric-Tuning Synthesis (DTS) Oxides: e.g. ZrO2, TiO2, BaTiO3, and ZrTiO4 • I. General introduction Uniqueness: • II. Chemical engineering of nanoparticles and • use inorganic precursors SEM material nanostructures • low temperature synthesis • III. Molecular “engineering” of nanostructures • different from − Array of nanochannels/nanotubes: sol-gel method orientation/ordering control • Capable of sol- gel processing − Space-confined self-assembly: nanostructure Features: control within nanowires XRD of • Size: near- • IV. Potential Applications monodispersed BaTiO3 • Phase: − Fuel cells, solar cells, sensors, … nanocrystalline or • V. Concluding Remarks amorphous • High purity • Nanoscale homogeneity • Controllable OAK RIDGE NATIONAL LABORATORY J. Colloid Inter. Sci.,222, 20 (2000). J. Mater. Sci. 35, 1 (2000). U. S. DEPARTMENT OF ENERGY J. Amer. Ceram. Soc., 82, 2313 (1999). morphology Powder Technol., 110, 2 (2000). Scale-up of DTS chemical process Besides large-scale production, control of nanoparticle assemblies is also a key engineering for nanoparticle synthesis issue (A) Nanocrystalline TiO2 Microspheres • Investigate engineering science issues: scale up, transition to continuous production (B)Nanocrystalline Microsphere Assemblies of BaTiO3 Glass vials (10-50mL) Engineering reactors (C) Dispersed Nanocrystals of BaTiO3 by Designed Dis-aggregation from Microsphere (5000mL, better control in T, Assemblies P, mixing parameters) OAK RIDGE NATIONAL LABORATORY U. S. DEPARTMENT OF ENERGY New Arenas:Arenas Engineering Control of the Laser Processing: Induced Nanocrystal Size and Nanostructures Homogenization Is Possible 2 orders-of-magnitude reduction in polydispersity! Current “Naked” Metallic Nanocrystals by A 2 orders-of-magnitude reduction in polydispersity! (from 0.5 to 0.005) while size does not change nanoscience effort Chemistry, materials science and Thermal Electrochemical Process in materials is engineering, etc. Scattering Characteristics of Sample Ag41 restrained inside (preliminary results) this box 1 0.9 0.8 without laser 0.7 Outside-the-Box Approach: “engineered” monitoring and control of processes 0.6 0.5 Laser-assisted processing 0.4 Diversified physical/chemical 0.3 with laser Field-directed processing Polydispersity means of engineering controls 0.2 (Electrical, Magnetic, Microwave…) 0.1 enable 0 Electrochemical processing 0 10203040506070 • novel and refined ways of This process, developed at ORNL, Time (min) Thermal processing manufacturing generates possibly a new class Molecular assembly-assisted • creation of new nanostructures of Ag nanocrystals. Polydispersity: a parameter in dynamic light scattering processing • better or more precise control of measurement to quantify particle size distribution. • Size < 10 nm • < 0.02, for monodisperse or nearly monodisperse samples process parameters • Free from any organic capping • 0.02-0.08, for narrow size distributions molecules • > 0.08, for broader distribution • Colloidally stable Field-Coupled Chemical Processing Microwave Processing Offers More Flexibility