The Case for Materials Characterization

Foothill College

NANO53

Overview

• The role of characterization

• PNPA model

• Types of information

• Example problems

• Materials analyzed

Why Characterize?

• Nanostructures are unknown

• QA/QC of fabrication process

• Failure analysis of products

• Materials characterization

• Process development / optimization

PNPA – Nanomaterials Engineering Rubric

• Applications drive requirements

• Requirements inform material selection

• Nanostructured materials engineering

• Process design and optimization

• Characterization tools and approach

PNPA – A Rubric for Training Technicians in Nanomaterials Engineering

PNPA - Characterization

Processing (P)

Properties (P)

Characterization

(N)Nanostructure

PLOs – Program Learning Outcomes – Integrated Materials Engineering Process

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Fabrication property relationships => <= Nanostructure elucidation

<= Process tools / QA/QC monitoring

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Nanostructural Information

• Morphology• Composition• Chemistry• Structure• Properties

Novel nanocarbon can store and sieve hydrogen - http://spie.org/x13545.xml?ArticleID=x13545

Process Optimization

• Relate structure to properties

• Relate structure to process

• Relate process to properties

• Optimize structure / property process / relationships

• Optimize process parameters for manufacturing / cost / safety etc.

Taguchi Methods

• Taguchi methods are statistical methods developed by Genichi Taguchi to improve the quality of manufactured goods, and more recently also applied to, engineering, biotechnology, marketing and advertising. Professional statisticians have welcomed the goals and improvements brought about by Taguchi methods, particularly by Taguchi's development of designs for studying variation, but have criticized the inefficiency of some of Taguchi's proposals.[5]

http://en.wikipedia.org/wiki/Taguchi_methods

Key Nanomaterials

• Polymers

• Metals/alloys

• Glasses/ceramics

• Nanocarbon

• Thin film coatings

• Silicon

• Particles

Energy of electrons in graphene in the tight-binding model, http://dx.doi.org/10.1103/PhysRev.71.622

What we Need to Know

• Surface finish

• Surface composition and chemistry

• Layer thickness

• Bulk composition and chemistry

• Material phase and structure

Types of Testing

• Materials characterization

• Process development support

• Failure analysis

• QA/QC

• Authenticity testing

Tools

• Image (SEM, AFM, TEM)• Surface (AES, XPS)• Organic (FTIR, Raman,

GC/MS, LC/MS, NMR• Chemical (ICP, XRF, TEM)• Structural (XRD, Raman)• Modeling and simulation

AFM Instrumentation

PNI Nano-R AFM Instrumentation as used at Foothill College

Surface Analysis Tools

SSX-100 ESCA on the left, Auger Spectrometer on the right

XPS Spectrum of Carbon

• XPS can determine the types of carbon present by shifts in the binding energy of the C(1s) peak. These data show three primary types of carbon present in PET. These are C-C, C-O, and O-C=O

Typical Problems

• Contamination

• Failure

• Process development

• Competitive analysis

• Research (R&D)

http://www.forensicinvestigation.com/

Nanocarbon

• Graphitic like structures – CNT, graphene, etc

• Soot that has been annealed (graphitized)

• Graphitic planes are observed by TEM

• No one knows what the 3D structure is

• Electron tomography might be useful

Biomedical Stents

• Surface finish is critical to patient outcomes, electropolishing etc.

• Multi-technique analysis– Image analysis– Surface analysis– Depth profiles

Identification of Contamination

• Organic contamination• Ionic residues• Cleaning residue• Process residue• Packaging transfer• Environmental

Surface Treatment of NiTi

Biomedical Devices and Biomedical Implants – SJSU Guna Selvaduray

Biomedical Devices and Biomedical Implants – SJSU Guna Selvaduray

Surface Treatment of NiTi

• XPS spectra of the Ni(2p) and Ti(2p) signals from Nitinol undergoing surface treatments show removal of surface Ni from electropolish, and oxidation of Ni from chemical and plasma etch. Mechanical etch enhances surface Ni.

Biomedical Devices and Biomedical Implants – SJSU Guna Selvaduray

Surface Treatment of NiTi

Multi-technique Analysis

• Image – surface morphology

• Surface – surface chemistry

• Structural – crystal domain

• Organic – molecular specific identification (separation)

• Chemical – elemental analysis

Modeling and Simulation

Not Being Blind

• Developing a process with NO characterization tools

• Using properties measurements only

• Not knowing why something is good

• Not knowing if you can do better

• Not having a baseline of quality