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24.11.2006 1 1 Universität Bremen [email protected] Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de Ceramic Nanotechnology Ceramic Nanotechnology Lecture 4 Lecture 4 Characterization of Characterization of Nano and Micro Particles Nano and Micro Particles Prof.Dr. Prof.Dr.- Ing Ing. Kurosch Rezwan Kurosch Rezwan krezwan@uni krezwan@uni-bremen.de bremen.de Bioceramics, FB4 Bioceramics, FB4 Universit Universität Bremen t Bremen Am Biologischen Garten 2, IW3 Am Biologischen Garten 2, IW3 D D - 28359 Bremen 28359 Bremen Tel: +49 421 218 4507 Tel: +49 421 218 4507 Fax: +49 421 218 7404 Fax: +49 421 218 7404 http://www.bioceramics.uni http://www.bioceramics.uni-bremen.de bremen.de/ 2 Universität Bremen [email protected] Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de Outline Course Outline Course „ Ceramic Nanotechnology Ceramic Nanotechnology“ 1. Introduction: Applications, Goals and Challenges 2. Powder Synthesis and Conditioning 3. Particle Interactions in Colloidal Systems 4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I 7. Stabilization of Suspensions and Additives II 8. Colloidal Processing and Rheology 9. Shaping Ceramics I: Bulk Materials 10. Shaping Ceramics II: Foams 11. Shaping Ceramics III: Thin Films 12. Sol – Gel Technology: From Molecules to Advanced Ceramics 13. Selected Applications of Ceramic Nanotechnology 14. Summary

CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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Page 1: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

24.11.2006

1

1Universität [email protected] 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@[email protected]

Bioceramics, FB4Bioceramics, FB4UniversitUniversitäät 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//

2Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Outline Course Outline Course „„Ceramic NanotechnologyCeramic Nanotechnology““1. 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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3Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

From Powder to Advanced CeramicsFrom Powder to Advanced Ceramics

Colloid Crystals

Surface Micro Patterning

?? ?? Bulk Materials

SurfaceCoatings

??

4Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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 μm→ narrow ± 10 %→ uniform

microstructure homogeneity

particle sizeparticle size distributionparticle shape

RemarksImpact on finished partProperties / Requirements

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5Universität [email protected] 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

6Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Outline LectureOutline Lecture

• Particle Morphology and Size

DensityDefinition Particle SizeMethods

• Other Particle Properties

Crystal PhaseZetapotential / IEPElemental CompositionInterfacial Tension

Page 4: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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7Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Overview Methods Particle Size MeasurementsOverview Methods Particle Size Measurements

8Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Overview Methods Particle Size MeasurementsOverview Methods Particle Size Measurements

Resolution

> 20 μm

1 nm - 5 μm

50 nm – 1000 μm

> 1 μm

1 nm – 100 μm

10 nm – 1000 μm

50 nm – 1000 μm

Method

Sieving

Light Scattering

Laser Diffraction

Coulter – Counter („Electrozone Sensing“)

Microscope (Optical / SEM / TEM)

Centrifuge Sedigraph with X-Ray Detection

Acoustic Spectroscopy

Page 5: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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9Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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

10Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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

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11Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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

12Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Particle Size Distribution ModesParticle Size Distribution Modes

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13Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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.

14Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Example Bimodal DistributionExample Bimodal Distribution

DMedian ≈ 30 µm

DMean ≈ 27 µm

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15Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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!

16Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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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17Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Light Microscope / SEM / TEMLight Microscope / SEM / TEM

Size Range> 1 µm> 10 nm SEM> 1 nm TEM

AdvantageMorphology directly observableNo assumptions need to be made

DisadvantageSEM/TEM expensivePoor Statistics

Size Agglomerate: 5 µmSize 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

18Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

SievingSieving

Size range> 20 µm

Advantagevery cheap

DisadvantageNot suitable for submicron and nano particlesLow resolution

“Sieving Towers” on a vibrating device

Page 10: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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19Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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 Detecto

r

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

20Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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 µm

AdvantageIn situ usable

DisadvantageSmall particle range

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21Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

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 size.

Size Range10 nm – 100 µm

AdvantageWide size range, Particle Size and Distribution are measured

DisadvantageParticles to be measured should not be X-ray transparent

22Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

XX--Ray Disc Centrifuge (XDC)Ray Disc Centrifuge (XDC)

X – RaySource

DetectorSpinningDisc

Page 12: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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23Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

XX--Ray Disc Centrifuge (XDC)Ray Disc Centrifuge (XDC)

( )( ) ifp

ifm

it

tSr

D

tBCII

⋅−=

−=

ρρωη

22

0

/ln18

))(exp(

sign

alin

tens

itytime

diameter

perc

enta

ge

X – RaySource

DetectorSpinningDisc

24Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Acoustic Spectroscopy: UltrasoundAcoustic Spectroscopy: Ultrasound

[Adapted from Meier L., Zürich]

Size Range10 nm - 1000 µm

AdvantageFast technique that can be applied in situ without altering the system.

DisadvantageOnly mono – and bimodal characterization possible.

Sound Absorption as a function of Frequency is measured.

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25Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

BET Measurement: Specific Surface AreaBET Measurement: Specific Surface Area

From the amount of gas adsorbed on the surface the surface area is calculated.Assumption: Monolayer Formation (Langmuir type of adsorption).

26Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

BET ApparatusBET Apparatus

Detection Range> 0.2 m2/g

AdvantageBest technique to determine the Specific Surface Area

DisadvantageParticle Size Distribution not measurable

ParticleBETAD

ρ⋅=

6Calculation Particle Diameter:

Gas Adsorption Method:Mostly N2 used

Page 14: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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27Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

BET Surface BET Surface vsvs Particle Diameter for SiOParticle Diameter for SiO22

1

10

100

1000

10000

1 10 100 1000

ABET [m2/g]

Part

icle

Dia

met

er [n

m]

ParticleBETAD

ρ⋅=

6

28Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Particle Size (μm)0.01 0.1 1 10 100 1000

Erro

r

Dispersion

SamplingInstrumentation

General Note: Repeatability/reproducibility of Particle Size MeGeneral Note: Repeatability/reproducibility of Particle Size Measurementsasurements

Relevance of Factors in repeatability and reproducibility

“Novices in the size-measurement field must understand that most errors in size measurement arise through poor sampling and dispersion and not through instrument inadequacies.”

[Advances in Ceramics, Vol 21: Ceramic Powder Science, page 721, The American Ceramic Society Inc. (1987)]

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29Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Outline LectureOutline Lecture

• Particle Morphology and Size

DensityDefinition Particle SizeMethods

• Other Particle Properties

Crystal PhaseZetapotential / IEPElemental CompositionInterfacial Tension

30Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Characterization of other Particle PropertiesCharacterization of other Particle Properties

Output

Crystal Phase

Elemental Composition

Zetapotential / Isoelectric Point

Interfacial Tension(Hydrophilicity / Hydrophobicity)

Method

X-Ray Diffraction (XRD)

X-Ray Fluorescence (XRF)

Colloidal Vibration Potential (CVP)

Pendant Drop Method (PDM)

Page 16: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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31Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

XX--Ray Diffraction (XRD): Determination of Crystal PhaseRay Diffraction (XRD): Determination of Crystal Phase

OutputsDetection of crystal structureCrystallite size from peak broadening with ScherrerEquation

2 Θ

Cou

nts/

s

32Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

XX--Ray Fluorescence (XRF): Determination of Elemental CompositionRay Fluorescence (XRF): Determination of Elemental Composition

OutputsDetection of Single Elements and their Ratio

Typical XRF Spectra

Page 17: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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33Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Principle XPrinciple X--Ray Fluorescence (XRF)Ray Fluorescence (XRF)

1. An electron in the K shell is ejected from the atom by an external primary excitation x-ray, creating a vacancy.

2. An electron from the L or M shell “jumps in” to fill the vacancy. In the process, it emits a characteristic x-ray unique to this element and in turn, produces a vacancy in the L or M shell.

34Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

The Colloidal Vibration Potential (CVP) Technique: ZetapotentialThe Colloidal Vibration Potential (CVP) Technique: Zetapotential and IEPand IEP

Information about:Zetapotential andIsoelectric point (IEP)

Accuracy: ± 0.15 pH± 1 mV

ultra soundfrequency ≈ 3 MHz

CVP

elec

trode

elec

trode

deflection

particle

[Dukhin, Langmuir, 1999]

''

''

*'

sg

sg

m

mpe

ZZZZCCVP

+⋅

⋅⋅−

⋅⋅⋅=ρκρρμϕ

C’: calibration constantϕ: volume fractionμe: dynamic electrophoretic mobility κ*: complex conductivity of dispersed

systemρp: density particleρm: density mediumZg, Zs: acoustic impedances of

the sound transducer and thedispersed system

Page 18: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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35Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Zeta Potential of selected Oxides and the IEPZeta Potential of selected Oxides and the IEP

-105-95-85-75-65-55-45-35-25-15

-55

1525354555657585

1 2 3 4 5 6 7 8 9 10 11 12

pH

Zeta

pote

ntia

l [m

V]

SilicaTitaniaZirconiaAlumina

IEP towardsbasic pH

Definition Isoelectric Point (IEP):pH where the Zetapotential equals Zero.

36Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

TaskDetermination of the interface and surface tension of liquids

OutputMeasurement of the static interfacial or surface tension as a function of time or of temperature

Measurement of the adsorption/diffusion coefficients of surfactant molecules in oscillating/relaxing drops

Typical measuring range0,05 ... 1000 mN/m

1 2

1 1Op gz

R Rρ γ

⎛ ⎞+ Δ = +⎜ ⎟

⎝ ⎠

where is the fitting parameterand the resulting surface tension

γ

Pendent Drop Method: Pendent Drop Method: HydrophilicityHydrophilicity / / --phobicityphobicity

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37Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

t0

Interfacial tension measurementInterfacial tension measurement

1 2

1 1Op gz

R Rρ γ

⎛ ⎞+ Δ = +⎜ ⎟

⎝ ⎠where γ is the fitting parameterand the resulting surface tension

tequilibrium

38Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Surface Tension measured for Oxide Particle SuspensionsSurface Tension measured for Oxide Particle Suspensions(at pH 7 in water/air, (at pH 7 in water/air, ““pendant drop methodpendant drop method””))

64

65

66

67

68

69

70

71

72

73

74

0 100 200 300 400 500 600 700Time [s]

Surf

ace

Tens

ion

[mN

m-1

]

Water, Silica

AluminaTitania

Zirconia

[Rezwan K., Diss. ETH 2005]

Page 20: CN 4 Characterization of Nano and Micro Particles file4. Characterization of Nano- and Micro Particles 5. Properties of Suspensions 6. Stabilization of Suspensions and Additives I

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39Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Surface Tension measured for Oxide Particle SuspensionsSurface Tension measured for Oxide Particle SuspensionsInterpretationInterpretation

60

65

70

75

Water Silica Titania Alumina Zirconia

Surf

ace

Tens

ion

[mN

/m]

decrease surface decrease surface tensiontension

Surface tension decreasesin the following order

SiO2>TiO2>Al2O3>>ZrO2

hydrophobicity

40Universität [email protected] Nanotechnology – L4www.bioceramics.uni-bremen.de

Outline Course Outline Course „„Ceramic NanotechnologyCeramic Nanotechnology““1. 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