CN 4 Characterization of Nano and Micro Particles . Characterization of Nano- and Micro Particles 5

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1Universitt Bremenkrezwan@uni-bremen.deCeramic Nanotechnology L4www.bioceramics.uni-bremen.de

Ceramic NanotechnologyCeramic NanotechnologyLecture 4Lecture 4Characterization ofCharacterization ofNano and Micro ParticlesNano and Micro Particles

Prof.Dr.Prof.Dr.--IngIng..Kurosch RezwanKurosch Rezwan

krezwan@unikrezwan@uni--bremen.debremen.de

Bioceramics, FB4Bioceramics, FB4UniversitUniversitt Brement BremenAm Biologischen Garten 2, IW3Am Biologischen Garten 2, IW3D D -- 28359 Bremen28359 Bremen

Tel: +49 421 218 4507Tel: +49 421 218 4507Fax: +49 421 218 7404Fax: +49 421 218 7404

http://www.bioceramics.unihttp://www.bioceramics.uni--bremen.debremen.de//

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Outline Course Outline Course Ceramic NanotechnologyCeramic Nanotechnology1. Introduction: Applications, Goals and Challenges2. Powder Synthesis and Conditioning3. Particle Interactions in Colloidal Systems4. Characterization of Nano- and Micro Particles5. Properties of Suspensions6. Stabilization of Suspensions and Additives I7. Stabilization of Suspensions and Additives II8. Colloidal Processing and Rheology9. Shaping Ceramics I: Bulk Materials10. Shaping Ceramics II: Foams11. Shaping Ceramics III: Thin Films12. Sol Gel Technology: From Molecules to Advanced Ceramics13. Selected Applications of Ceramic Nanotechnology14. Summary

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3Universitt Bremenkrezwan@uni-bremen.deCeramic Nanotechnology L4www.bioceramics.uni-bremen.de

From Powder to Advanced CeramicsFrom Powder to Advanced Ceramics

Colloid Crystals

Surface Micro Patterning

?? ?? Bulk Materials

SurfaceCoatings

??

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Requirements for Ceramic Powder SynthesisRequirements for Ceramic Powder Synthesis

Exact fixation of chemical composition Production of specific particle sizes and particle size distributions High sintering activity Economic synthesis: broad application/usability of powders Environment-friendly and energy saving processes

surface properties e.g. of colloid surface

Processing properties

crack formation/crack propagation

absence of large size secondary phasesabsence of agglomerates/aggregates

low ppm range defined

microstructure compositionlow impurity level in powder particlesphase composition

< 1 m narrow 10 % uniform

microstructure homogeneity

particle sizeparticle size distributionparticle shape

RemarksImpact on finished partProperties / Requirements

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5Universitt Bremenkrezwan@uni-bremen.deCeramic Nanotechnology L4www.bioceramics.uni-bremen.de

How to Characterize Nano and Micro Particles?How to Characterize Nano and Micro Particles?

Density

Morphology

Diameter & Size Distribution

Specific Surface Area

Surface & Bulk Composition

Crystal Phase

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Outline LectureOutline Lecture

Particle Morphology and Size

DensityDefinition Particle SizeMethods

Other Particle Properties

Crystal PhaseZetapotential / IEPElemental CompositionInterfacial Tension

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Overview Methods Particle Size MeasurementsOverview Methods Particle Size Measurements

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Overview Methods Particle Size MeasurementsOverview Methods Particle Size Measurements

Resolution

> 20 m

1 nm - 5 m

50 nm 1000 m

> 1 m

1 nm 100 m

10 nm 1000 m

50 nm 1000 m

Method

Sieving

Light Scattering

Laser Diffraction

Coulter Counter (Electrozone Sensing)

Microscope (Optical / SEM / TEM)

Centrifuge Sedigraph with X-Ray Detection

Acoustic Spectroscopy

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What is Porosity / Density?What is Porosity / Density?

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Measuring the Density: Liquid or Gas Measuring the Density: Liquid or Gas PycnometeryPycnometery

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What is What is Particle SizeParticle Size??

deq: equivalent diameter

2-dimensional:circle with equivalent area as projection area of particle

3-dimensional:sphere with similar total volume as particle

deq

XF: Feret diameter

Distance between 2 tangentsto the particle contour

XFmin: smallest feret diameterXFmax: largest feret diameter

XFminXFmax

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Particle Size Distribution ModesParticle Size Distribution Modes

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Cumulative and Differential Particle Size DistributionCumulative and Differential Particle Size Distribution

cumulative volume distribution differential distribution

Particle Diameter D Particle Diameter Dd50

The MEDIAN Diameter is called D50.

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Example Bimodal DistributionExample Bimodal Distribution

DMedian 30 m

DMean 27 m

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Different Particle Size DefinitionsDifferent Particle Size Definitions

volume distribution: the contribution to the mass is mostly caused by the bigger particles

numerical distribution(each particlecontributes)

Different Measurement methods can result in different results!

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Comparison number/volume distributionComparison number/volume distribution

volume distributionnumber distribution

Emphasis on small particles due to their large number.

Particles are weighted according to their volume

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Light Microscope / SEM / TEMLight Microscope / SEM / TEM

Size Range> 1 m> 10 nm SEM> 1 nm TEM

AdvantageMorphology directly observableNo assumptions need to be made

DisadvantageSEM/TEM expensivePoor Statistics

Size Agglomerate: 5 mSize Particle : 37 nm !

The National Bureau of Standards has stated that at least 10,000 separate images (not particles) need to be measured for statistical accuracy in image analysis

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SievingSieving

Size range> 20 m

Advantagevery cheap

DisadvantageNot suitable for submicron and nano particlesLow resolution

Sieving Towers on a vibrating device

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Scattering of light by particles. Detector, shown in red, measures angles and light intensities.

The diffusion coefficient D of the moving particles is obtained from the fluctuating scattering pattern. From the diffusion coefficient the hydrodynamic radius RH is calculated.

Particle Size: Light/Laser ScatteringParticle Size: Light/Laser Scattering

1. The scattered lights from each particle reach to the to detector together

2. They interfere mutually.3. As the particles move, the intensity of the

scattered lights are changed with time.

StrenghtenedPosition Scattered

Light Detec

tor

Size Range1 nm 5 m (Light Scattering)50 nm - 5 m (Laser Scattering)AdvantageSmall particles measurableDisadvantageExpensive, small particles may be concealed

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Coulter Counter (Coulter Counter (Electro sensing ZoneElectro sensing Zone))

Particles suspended in a weak electrolyte solution are drawn through a small aperture, separating two electrodes between which an electric current flows. The voltage applied across the aperture creates a "sensing zone". As particles pass through the aperture (or "sensing zone"), they displace their own volume of electrolyte, momentarily increasing the impedance of the aperture. the pulse is directly proportional to the 3-dimensional volume of the particle that produced it.

Size range1 - 100 m

AdvantageIn situ usable

DisadvantageSmall particle range

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Particle Size: XParticle Size: X--Ray Ray SedigraphySedigraphyParticles falling in a liquid medium. Yellow line coming from the left represents the X-ray source. Not all the X-rays reach the detector. Amount of X-rays adsorbed by the sample represents the mass of particles at specific si