2006 International Conference on Nanotechnology, April 26-28, 2006 Atlanta, GA The Challenges and Opportunities of The Challenges and Opportunities of Measuring Properties of Nanoparticles Measuring Properties of Nanoparticles and Nanostructured Materials: and Nanostructured Materials: Importance of a Multi- Importance of a Multi -Technique Approach Technique Approach D. R. Baer, M. H. Engelhard, C D. R. Baer, M. H. Engelhard, C- -M. Wang, A. S. Lea, K. M. Wang, A. S. Lea, K. Pecher Pecher Presented by: Donald R. Baer Environmental Molecular Sciences Laboratory, Pacific Northwest National Your logo here Laboratory
Four Messages Four Messages 1. Adequate characterization frequently requires an integrated multi- -technique approach technique approach integrated multi 2. For fundamental reasons nano-structured materials are a challenge to characterize. challenge to characterize. 3. 3. Routine sample handling, data collection, and analysis Routine sample handling, data collection, and analysis approaches may not be satisfactory – near state of the approaches may not be satisfactory art data analysis, data modeling, and use of information from other methods can be important. 4. Exciting opportunities – There are many new methods, 4. Exciting opportunities major advances in older methods, and new approaches to data analysis. Use all resources available including User Facilities (including National Labs) and recommended practices (ASTM and ISO).
Nanoscience Related Nobel Prizes Nanoscience Related Nobel Prizes Imaging & Manipulating Matter Imaging & Manipulating Matter The rapid development of nanoscience and nanotechnology has been fueled by several discoveries and the development of computational and experimental tools. We have many wonderful tools for handling and examining nano-structures. One of the greatest impacts has been the visualization and measurements at the atomic level enabled by scanning probe microscopy methods. Scanning Tunneling Microscopy Pt nanoclusters Pt nanoclusters Pt Pt nanoclusters on nanoclusters on on anatase on anatase anatase anatase • Nobel Prize in Physics in 1986 V x V x x V x V V y V y V z V z Supramolecular Chemistry V V V V • y y z z Nobel Prize in Chemistry 1987 Control Control Control Control Unit Unit Unit Unit I T I T I I T T Ion Trap • V T V T V V Nobel Prize in Physics 1989 T T Pt on TiO Pt on TiO 2 Pt on TiO 2 Pt on TiO 2 ( 2 ( (anatase (anatase anatase) anatase) ) ) Fullerenes or “Buckeyballs” • Nobel Prize in Chemistry 1996 Molecular Tweezers • Nobel Prize in Physics 1997
We have tools to obtain lots of very useful and important information. However, are the tools we have capable and being used to provide the information we need? “Which way is the men’s room?”
Four Messages Four Messages 1. Adequate characterization frequently requires an integrated multi integrated multi- - technique approach technique approach 2. For fundamental reasons nano-structured materials are a challenge to characterize. challenge to characterize. 3. Routine sample handling, data collection, and analysis 3. Routine sample handling, data collection, and analysis approaches may not be satisfactory – near state of the approaches may not be satisfactory art data analysis, data modeling, and use of information from other methods can be important. 4. Exciting opportunities – There are many new methods, 4. Exciting opportunities major advances in older methods, and new approaches to data analysis.
Possible use of iron nanoparticles to assist environmental remediation one research area driving analysis needs Toxic Breakdown Products HCCl 3 (CF) +1 e - +•H - 1 Cl - •CCl 3 CCl 4 (CT) +1 e - : CCl 2 - 1 Cl - HCOOH, CO, etc. Benign Breakdown Products • Transmission Electron Microscopy – Size, structure, shape • X-ray Photoelectron Spectroscopy – Surface Chemistry; Composition; Contamination • Surface Area – Gas Adsorption - BET • XRD – Structure, Grain Size • Reaction Studies and Electrochemical Measurements • X-ray adsorption Spectroscopy - electronic structure, oxidation state, property variation • Modeling – Structure, Transport Properties
Nano Particle Handling Nano Particle Handling • HRTEM/TEM Samples processed in methanol, TTFE or water, dried and transported to TEM in air. Samples mounted on TEM grid with no processing and transported to TEM in air. • XRD Dried in glove box and packed into XRD mount. Samples coated with glycerol and mounted on TEM grid. • XPS Mounted in glove bag and loaded into Vacuum system without exposure to air. • STXM Mounted in air on TEM grid • Electrochemistry and Kinetic (batch studies) Glove box dried. Flash Dried using methanol and vacuum system.
Summary of Two Particle Types Zhang Nano Iron Fe BH Toda Nano Iron Fe H2 5 nm 5 nm Mostly Fe 0 20 to 60 nm Two phase system: 30-60 nm Fe 0 spheres with boron oxide rich particles with oxide shell/coating and coating and made up of <1.5 made up of ∼ 30 nm grains and 30-100 nm grains. Assembled into nm Fe 3 O 4 particles. Also collected into larger aggregates aggregates .
Material size and surface areas Supplier claims Name Particle Size Surface Area Major Minor [m 2 /g] Diameter Phase Phase Fe H2 -Fe 0 70 nm 29 [4-60] Magnetite α Fe BH Fe 0 10-100nm 33.5 Goethite Fe EL 99% Fe 0 150 mm 0.1-1 Our Measurements Name Particle Size Surface Area Major Minor [m 2 /g] Diameter [nm] Phase Phase TEM BET Fe H2 Fe 0 /Magnetite 40 nm 3.5 3 Oxide shell ∼ Fe BH Fe 0 60 [20-100]nm 7-8.5 5 Boron oxide coating ∼ Fe EL Fe 0 150 mm 0.15
Information needed about nano- -structured materials? structured materials? Information needed about nano Results of Synthesis or Processing: size and size distribution Experimental composition and structure Axes component segregation • Energy; Composition; surface contamination Spectroscopy; Structure defect concentration • Resolution; Dimension; shape Position 2 Dimensional Analysis Position Composition
Information needed about nano- -structured materials? structured materials? Information needed about nano Results of Synthesis or Processing: Experimental size and size distribution Axes Change to composition and structure Multi Dimensional component segregation Analysis surface contamination •Energy/composition defect concentration •Resolution/Dimension shape •Time •Environment Influence of History, Aging (Time) and Environment: processing aggregation and growth environmental interactions reactive layer formation structure changes with time Multi Axis Analysis from Bob Analyses are usually done assuming that the Hwang BNL properties are independent of time and environment.
Ion Beam Damage of Nano Particles Fe 2 O 3 20 nm particles collected on Au Fe 2 O 3 film on Al 2 O 3 as received and after 2 kV Ar + ion sputter (3 nm for SiO 2 ) coated Si substrate as received and after 2 kV Ar+ ion sputter (2 nm for SiO 2 ) Fe 2p photoelectron peaks 1 1 0.9 0.9 0.8 0.8 0.7 Normalized Intensity 0.7 Normalized Intensity 0.6 0.6 Sputtered sputtered 0.5 0.5 0.4 0.4 0.3 0.3 0.2 0.2 As deposited 0.1 0.1 0 0 740 735 730 725 720 715 710 705 700 745 740 735 730 725 720 715 710 705 700 Binding Energy (eV) Binding Energy (eV) Significant reduction of particles Very little selective sputtering and oxide reduction
How can we determine if the damage (and sputter rate effects) we see on nanoparticles are really different than those of thin films? We need to understand the impact of particle shape on the information we collect Information needed to answer question: Particle Sizes and Shapes (other data) Model for XPS signals for two systems Electron Inelastic Mean Free Path Lengths
Four Messages Four Messages 1. Adequate characterization frequently requires an integrated multi- -technique approach technique approach integrated multi 2. For fundamental reasons nano-structured materials are a challenge to characterize. challenge to characterize. Nanostructures Materials can have Nanostructures Materials can have unexpected behaviors. of unexpected behaviors. of 3. Routine sample handling, data collection, and analysis 3. Routine sample handling, data collection, and analysis approaches may not be satisfactory – near state of the approaches may not be satisfactory art data analysis, data modeling, and use of information from other methods can be important. 4. Exciting opportunities – There are many new methods, 4. Exciting opportunities major advances in older methods, and new approaches to data analysis.
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