Ceramic Nanotechnology Lecture 4 Characterization of Nano and Micro Particles
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 - bremen.de
- krezwan@uni bremen.de
Bioceramics, FB4 Bioceramics, FB4 Universit Universit ä ä t Bremen t Bremen Am Biologischen Garten 2, IW3 Am Biologischen Garten 2, IW3 D - 28359 Bremen D 28359 Bremen - Tel: +49 421 218 4507 Tel: +49 421 218 4507 Fax: +49 421 218 7404 Fax: +49 421 218 7404 bremen.de - http://www.bioceramics.uni / bremen.de - http://www.bioceramics.uni / 1 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ 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 2 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de
¾ ¾ From Powder to Advanced Ceramics From Powder to Advanced Ceramics ? ?
Bulk Materials
? ? ? ?
Surface Micro Patterning Surface Coatings
Colloid Crystals 3 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Requirements for Ceramic Powder Synthesis Requirements 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
Properties / Requirements Impact on finished part Remarks
particle size microstructure → < 1 μm particle size distribution homogeneity → narrow ± 10 % particle shape
→ uniform low impurity level in powder particles microstructure composition → low ppm range phase composition
→ defined absence of large size secondary phases crack formation/crack absence of agglomerates/aggregates propagation Processing properties surface properties e.g. of colloid surface 4 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de
- Den
- Morphology • Diameter & Size Distribution • Specific Surface Area • Surface & Bulk Composition • Crystal Phase
5 Universität Bremen
krezwan@uni-bremen.de
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ How to Characterize Nano and Micro Particles? How to Characterize Nano and Micro Particles?
- Particle Morphology and Size Density Definition Particle Size Methods
- Other Particle Properties Crystal Phase Zetapotential / IEP Elemental Composition Interfacial Tension
6 Universität Bremen
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Outline Lecture Outline Lecture
7 Universität Bremen
krezwan@uni-bremen.de
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Overview Methods Particle Size Measurements Overview Methods Particle Size Measurements
8 Universität Bremen
krezwan@uni-bremen.de
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Overview Methods Particle Size Measurements Overview 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
¾ ¾ What is Porosity / Density? What is Porosity / Density? 9 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Measuring the Density: Liquid or Gas Measuring the Density: Liquid or Gas Pycnometery Pycnometery 10 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de
¾ ¾ What is What is “ “ Particle Size Particle Size ” ” ? ? d : equivalent diameter eq 2-dimensional: circle with equivalent area as projection area of particle d eq
3-dimensional: sphere with similar total volume as particle
X F : Feret diameter
Distance between 2 tangentsX Fmin
to the particle contour
X Fmax X : smallest feret diameter
Fmin X : largest feret diameter
Fmax 11 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Particle Size Distribution Modes Particle Size Distribution Modes 12 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
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¾ ¾ Cumulative and Differential Particle Size Distribution Cumulative and Differential Particle Size Distribution cumulative volume distribution differential distribution d 50 Particle Diameter D Particle Diameter D The MEDIAN Diameter is called D .
50 13 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Example Bimodal Distribution Example Bimodal Distribution
D ≈ 30 µm
Median
D ≈ 27 µm
Mean 14 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
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www.bioceramics.uni-bremen.de
15 Universität Bremen
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Different Particle Size Definitions Different Particle Size Definitions volume distribution:
the contribution to the mass is mostly caused by the bigger particles
numerical distribution
(each particle contributes) Different Measurement methods can result in different results!
16 Universität Bremen
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Comparison number/volume distribution Comparison number/volume distribution
volume distribution number distribution Emphasis on small particles due to their large number.
Particles are weighted according to their volume
¾ ¾ Light Microscope / SEM / TEM Light Microscope / SEM / TEM Size Range
> 1 µm > 10 nm SEM > 1 nm TEM
Advantage
Morphology directly observable No assumptions need to be made
Disadvantage
SEM/TEM expensive Poor Statistics
The National Bureau of Standards has stated that at least 10,000 separate images (not Size Agglomerate: 5 µm particles) need to be measured for statistical
Size Particle : 37 nm ! accuracy in image analysis 17 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Sieving Sieving
Size range > 20 µm Advantage very cheap
“Sieving Towers” on a Disadvantage vibrating device Not suitable for submicron and nano particles
Low resolution 18 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
Universität Bremen
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19 Universität Bremen
2. They interfere mutually.
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Coulter Counter ( Coulter Counter ( “ “ Electro sensing Zone Electro 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.
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Size Range 1 nm – 5 µm (Light Scattering) 50 nm - 5 µm (Laser Scattering) Advantage Small particles measurable Disadvantage Expensive, small particles may be concealed
D et ec to r
Scattered Light
Strenghtened Position
3. As the particles move, the intensity of the scattered lights are changed with time.
1. The scattered lights from each particle reach to the to detector together
krezwan@uni-bremen.de
¾ ¾ Particle Size: Light/Laser Scattering Particle Size: Light/Laser Scattering
is calculated.
hydrodynamic radius R H
moving particles is obtained from the fluctuating scattering pattern. From the diffusion coefficient the
diffusion coefficient D of the
The
Scattering of light by particles. Detector, shown in red, measures angles and light intensities.
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de
Size range 1 - 100 µm Advantage In situ usable Disadvantage Small particle range
¾ ¾ Particle Size: X - Ray - Particle Size: X Ray Sedigraphy Sedigraphy
Particles 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 Range
10 nm – 100 µm
Advantage
Wide size range, Particle Size and Distribution are measured
Disadvantage
Particles to be measured should not be X- ray transparent 21 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ -
X Ray Disc Centrifuge (XDC) ¾ X - Ray Disc Centrifuge (XDC)
Spinning Disc
Detector X – Ray Source 22 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de
¾ ¾ - -
X X Ray Disc Centrifuge (XDC) Ray Disc Centrifuge (XDC)
Spinning Disc
Detector X – Ray Source intensity
l signa
I I exp( BC ( t )) = − t i
time
18 ln r / S η ( ) f i
2 D = m
2 − ⋅ t
ω ( ρ ρ ) p f i percentage
diameter 23 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Acoustic Spectroscopy: Ultrasound Acoustic Spectroscopy: Ultrasound
Size Range
10 nm - 1000 µm
Advantage
Fast technique that can be applied in situ without altering the system.
Disadvantage
Only mono – and bimodal characterization possible.
Sound Absorption as a function of Frequency is measured.
[Adapted from Meier L., Zürich] 24 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
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¾ ¾ BET Measurement: Specific Surface Area BET 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). 25 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ BET Apparatus BET Apparatus
Gas Adsorption Method: Mostly N used
2 Calculation Particle Diameter:
6 D = A ⋅ ρ
BET Particle Detection Range
2
> 0.2 m /g
Advantage Best technique to determine the Specific Surface Area Disadvantage Particle Size Distribution not measurable 26 krezwan@uni-bremen.deCeramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de
¾ ¾ BET Surface BET Surface vs vs Particle Diameter for SiO Particle Diameter for SiO
2 10000
2
6 ]
D = m n
A ⋅ ρ
BET Particle 1000
[ eter m 100 ia D icle
10 rt a P
1
1 10 100 1000
2 A [m /g] BET
27 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ General Note: Repeatability/reproducibility of Particle Size Me General Note: Repeatability/reproducibility of Particle Size Me asurements asurements ¾
Relevance of Factors in repeatability and reproducibility
Dispersion
“Novices in the size-measurement field must understand that most errors in size measurement arise through poor sampling and dispersion and not through
Sampling instrument inadequacies.” Error
Instrumentation [Advances in Ceramics, Vol 21: Ceramic Powder Science, page 721, The American Ceramic Society Inc. (1987)]
0.01
0.1
1 10 100 1000 Particle Size ( μm) 28 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
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- Particle Morphology and Size Density Definition Particle Size Met
- Other Particle Properties Crystal Phase Zetapotential / IEP Elemental Composition Interfacial Tension
29 Universität Bremen
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Outline Lecture Outline Lecture
30 Universität Bremen
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Characterization of other Particle Properties Characterization 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)
31 Universität Bremen
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾
X X - - Ray Diffraction (XRD): Determination of Crystal Phase Ray Diffraction (XRD): Determination of Crystal Phase Outputs
Detection of crystal structure Crystallite size from peak broadening with Scherrer Equation
2 Θ Counts/s
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Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾
X X - - Ray Fluorescence (XRF): Determination of Elemental Composition Ray Fluorescence (XRF): Determination of Elemental Composition Outputs
Detection of Single Elements and their Ratio
Typical XRF Spectra
¾ ¾ Principle X Principle 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. 33 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
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www.bioceramics.uni-bremen.de The Colloidal Vibration Potential (CVP) Technique: Zetapotential and IEP ¾ ¾ The Colloidal Vibration Potential (CVP) Technique: Zetapotential and IEP
CVP
particle deflection ultra sound electrode electrode frequency
≈ 3 MHz ' ' C’: calibration constant
ρ p − ρ m Z g ⋅ Z s
ϕ: volume fraction
e CVP = C ' ⋅ ϕ ⋅ μ ⋅ ⋅ ' ' +
μ : dynamic electrophoretic mobility e
⋅ m g s κ ρ Z * Z
κ*: complex conductivity of dispersed system ρ : density particle p ρ m : density medium
Information about:
Z , Z : acoustic impedances of g s Zetapotential and the sound transducer and the
Ø
Isoelectric point (IEP) dispersed system
Accuracy: ± 0.15 pH [Dukhin, Langmuir, 1999]
± 1 mV 34 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
Universität Bremen
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¾ ¾ Zeta Potential of selected Oxides and the IEP Zeta Potential of selected Oxides and the IEP
85 Silica
75 Titania
IEP towards
65 Zirconia
55 basic pH
45 Alumina
35
25 V]
15
5 ial [m -5
1
2
3
4
5
6
7
8
9
10
11
12 -15 tent -25 -35 Zetapo -45 -55 -65 -75 -85
Definition Isoelectric Point (IEP):
- -95
- -105 pH where the Zetapotential equals pH Zero. 35 krezwan@uni-bremen.de
- p + Δ ρ gz = γ coefficients of surfactant molecules in
- Δ = + ⎜ ⎟ ⎝ ⎠
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ Pendent Drop Method: Pendent Drop Method: Hydrophilicity Hydrophilicity / / phobicity - phobicity -
Task
Determination of the interface and surface tension of liquids
Output
Measurement of the static interfacial or surface tension as a function of time or of temperature Measurement of the adsorption/diffusion
⎛ ⎞
1
1
O ⎜ ⎟
oscillating/relaxing drops
R R
1
2 ⎝ ⎠
Typical measuring range
where is the fitting parameter γ0,05 ... 1000 mN/m
and the resulting surface tension 36 krezwan@uni-bremen.de Ceramic Nanotechnology – L4
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” ”
74 100 200 300 400 500 600 700 Time [s] S u rf ace Ten s io n [mNm -1 ] Water, Silica Alumina
73
72
71
70
69
68
67
66
65
64
) )
“ “ pendant drop method pendant drop method
37 Universität Bremen
Surface Tension measured for Oxide Particle Suspensions (at pH 7 in water/air, (at pH 7 in water/air,
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de ¾ ¾ Surface Tension measured for Oxide Particle Suspensions
krezwan@uni-bremen.de
38 Universität Bremen
where γ is the fitting parameter and the resulting surface tension t equilibrium
ρ γ ⎛ ⎞
1 O p gz R R
1
2
1
¾ ¾ Interfacial tension measurement Interfacial tension measurement
Ceramic Nanotechnology – L4 www.bioceramics.uni-bremen.de t
krezwan@uni-bremen.de
Titania Zirconia [Rezwan K., Diss. ETH 2005]
¾ ¾ Surface Tension measured for Oxide Particle Suspensions Surface Tension measured for Oxide Particle Suspensions Interpretation Interpretation
75
Ö Surface tension decreases in the following order
70 SiO >TiO >Al O >>ZrO
2
2
2
3
2 ion [mN/m] hydrophobicity Tens e c a
65
rf u S
60 Water Silica Titania Alumina Zirconia
decrease surface decrease surface tension tension 39 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de ¾ ¾ 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 40 krezwan@uni-bremen.de
Ceramic Nanotechnology – L4
Universität Bremen
www.bioceramics.uni-bremen.de