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SCHOTT North America, Inc. Interfaces in Functional Materials
Practical aspects and implications of interfaces in glass-ceramics
Mark J. DavisSCHOTT North America, Inc.
Outline
Key questions to address
Interfacial effects in glass-ceramics---a laundry list
Glass-ceramics in general: SCHOTT commercial examples
Commercial or near-commercial gc / interface examples
Key questions: review
SCHOTT North America, Inc. Interfaces in Functional Materials
Key Questions (from H. Jain)
What has been the role of interfaces in the development of
emerging applications?
With regard to applications, what aspects of interfaces are most
important and why?
What are the scientific issues that require basic understanding
of interfaces in glass-ceramics? What is the relative importance
of each?
What properties of glass-ceramics hold promise for the future?
SCHOTT North America, Inc. Interfaces in Functional Materials
Microstructural developmentsurface energies and their impact on nucleation
general glass stability; controlled vs. un-controlled crystallization (i.e., critical cooling rate in a commercial setting vs. academic…)
Structuraldetailed nature of interface (e.g., “pristine”, microcracked…)
crack blunting processes
residual stresses, crystal clamping
permeability
ElectricalEffective connectivity
Resistive / capacitive behavior
Opticalscattering effects
Practical Effects (Internal)
SCHOTT North America, Inc. Interfaces in Functional Materials
Joining (low-temperature)Hydrophilic vs. hydrophobic surfaces
Competitive bonding technologies
Glass-to-metal sealing (high-temperature)Flow vs. crystallization “stiffening”
Interfacial reactions
Hermeticity (CTE matching)
PolishingCrystal vs. glass effects (mostly proprietary know-how)
Practical Effects (External)
SCHOTT North America, Inc. Interfaces in Functional Materials
Why glass-ceramics?Single Crystals often exhibit the highest property performance,
but are generally more difficult and expensive to manufacture
Ceramics are easier to manufacture, but are typically porous to
some degree and may exhibit inhomogeneities, aging, decreased
strength, etc.
Glasses take advantage of processing ease, homogenization
efficiency, and tailorable compositions, but lack certain functions
(e.g., novel CTE combinations, lack of center-of-symmetry)
Glass-ceramics can be seen as “glass packaged crystals” and
combine the ease of glass processing and potential for new
property combinations (e.g., ultra-low thermal expansion, 2nd-
harmonic generation, piezoelectricity)
SCHOTT North America, Inc. Interfaces in Functional Materials
How is a commercial glass-ceramic produced?
Ceramization
Melting
glass
glass-ceramic
Inspection
SCHOTT North America, Inc. Interfaces in Functional Materials
Thermal expansion tailoring
From Sect. 6.5, Glass-Ceramics for Optical Applications, M. Davis in Optical Materials and Their Applications, Springer-Verlag
Aluminum
Same composition for all curvesMicrocracking and hysteresis
SCHOTT North America, Inc. Interfaces in Functional Materials
Pressed glass-ceramic reflectors
Glass-ceramic cooktops
Examples of SCHOTT glass-ceramics
Ring-laser gyroscopes
8.2 m telescope mirror blanks
SCHOTT North America, Inc. Interfaces in Functional Materials
VLT telescope in Chile (8.2 m mirrors with adaptive optics)
(www.eso.org)
Zerodur mirror fabrication
On the road to Cerro Paranal, Chile
Large mirror blank production (Zerodur)Large mirror blank production (Zerodur)
SCHOTT North America, Inc. Interfaces in Functional Materials
Non-isothermal ~2 oC/hr
bar = 200 nm
Maier and Muller, 1987
~50 nm high-quartz solid-solution crystals~50 nm high-quartz solid-solution crystals
Typical LAS (Zerodur) glass-ceramic microstructure
Internal surface area ~ 30 m2/gm
~1022 m-3 HQSS crystals
~1025 m-3 ZrTiO4 crystals
SCHOTT North America, Inc. Interfaces in Functional Materials
Isothermal heat treatment
Petzoldt and Pannhorst, 1991
SCHOTT North America, Inc. Interfaces in Functional Materials
Permeability of Zerodur
*
*Fused Silica
*
*Zerodur
Pyrex/Duran*
*Fused Silica
*
*Fused Silica
*
*Zerodur
*
*Zerodur
Pyrex/Duran
Figure from Suckow et al. (1990)
SCHOTT North America, Inc. Interfaces in Functional Materials
Zerodur permeability enables high-precision RLG production
Ring Laser Gyroscope (RLG)
Sagnac EffectSagnac Effect
SCHOTT North America, Inc. Interfaces in Functional Materials
World’s biggest RLG (Bavarian Forest)to measure subtle Earth motions
SCHOTT North America, Inc. Interfaces in Functional Materials
IR only (visible blocking filter RG 1000)λ > 850 nm
Scattering example in glass-ceramics (DWDM substrate)
small particle limit:
ρλ
τ 42
3 1)(3
4 nnaΔ⋅=
Rayleigh (1881)
Visible light only (IR blocking filter KG3)λ < 850 nm
Sample thickness ~ 35 mm
Crystal size ~35 nm
SCHOTT North America, Inc. Interfaces in Functional Materials
Quantitative scattering example in glass-ceramics (Zerodur)
From Sect. 6.5, Glass-Ceramics for Optical Applications, M. Davis in Optical Materials and Their Applications, Springer-Verlag
λ-4 dependence
λ-8 dependence
SCHOTT North America, Inc. Interfaces in Functional Materials
Expected behavior
Crystal clamping of a FE phase (Lynch and Shelby 1984)
GlassGlass
PbTiO3
No crystalclamping
Crystalclamping
Also Grossman and Isard (1969)
Assuming ~1% strains and E ~ 260 GPa, calculated residual stresses ~ 3 GPa (!)
SCHOTT North America, Inc. Interfaces in Functional Materials
Residual stress studies (crystal/glass interface)
Estimated from data of Grossman and Isard (1969)
~3000 (?)PbTiO3 – BaO – B2O3
Zevin et al. (1978)~400LAS
Mastelaro and Zanotto (1996)~200Soda-lime silicate
Mastelaro and Zanotto (1999)~150Li2O-2SiO2
SourceMax |σ| (MPa)System
⇒ In all cases, calculated stresses >> nominal 20 MPatensile strength of typical (imperfect) external glass surfaces
SCHOTT North America, Inc. Interfaces in Functional Materials
Engineered microstructure examples (G. Beall)
Fluorrichterite
Canasite
Enstatite
High Crystallinity
Interlocking Crystals
Grain-size from 1-10 μm
Acicular Crystals (Rods)
Bladed Crystals (Laths)
Polysynthetic Twinning
SCHOTT North America, Inc. Interfaces in Functional Materials
PhysisorbedChemisorbed
Si
Si
Li+O OO O O
O OHOH OH
OH OHOH
Al
Al
Li+Li+O O O
O OHOH
H HO
HHO
HHOH HO HH
OH HO H HO
HHO
H HO
H HO
Si
Si Al
Al
Si
Si
AlSiSi
Si Si Si HydrophilicSurface
Bulk Zerodur
PhysisorbedChemisorbed
Si
Si
Li+O OO O O
O OHOH OH
OH OHOH
Al
Al
Li+Li+O O O
O OHOH
H HO
HHO
HHOH HO HH
OH HO H HO
HHO
H HO
H HO
Si
Si Al
Al
Si
Si
AlSiSi
Si Si Si HydrophilicSurface
Bulk Zerodur
A lLi +
OOH OHOH
OHOH OH
A lLi +
OOH OH
HHO
HHO
Li +
O OHOH OHOH OHOH
A l
O OHOH
H HO
HHO
H HOH HO
HHO
O
OHOHO
O
OHOHOO
OHOHO
OH
OHOHO
O
OOHOO
OHO
OO
OOHO
Li +
Li +
Li +
Li +
OH-
OH-
OH-
OH-
OH-HH HO
+
HH HO
+
Si
Si
SiSiAlSiSiSi
Si
Si
SiSi
SiSi
Si Al Si Si Si Al
InorganicJoiningLiquid
Bulk Zerodur
Bulk Zerodur
OriginalSurfaces
A lLi +
OOH OHOH
OHOH OH
A lLi +
OOH OH
HHO
HHO
Li +
O OHOH OHOH OHOH
A l
O OHOH
H HO
HHO
H HOH HO
HHO
O
OHOHO
O
OHOHOO
OHOHO
OH
OHOHO
O
OOHOO
OHO
OO
OOHO
Li +
Li +
Li +
Li +
OH-
OH-
OH-
OH-
OH-HH HO
+
HH HO
+
Si
Si
SiSiAlSiSiSi
Si
Si
SiSi
SiSi
Si Al Si Si Si Al
InorganicJoiningLiquid
Bulk Zerodur
Bulk Zerodur
OriginalSurfaces
Al Li +
O
O
OO
O
O
Al
AlLi +Al
H HO
OH
H HOHH
O
OH O
O
OO
O
OH HO
H HO
H HO
OH
OLi +Li +
O
O
OO
O
OO
Li +
Li +
H HO
OH
H HO
H HO
H HO
H HO
H HO
OH OH
Si
Si Si
SiAlSiSiSi
SiSi Si Si
Si
Si
Si
Si
SiAl
ReAl
Si
Si
Si
Bulk Zerodur
Bulk Zerodur
RigidJoint
Interface
OriginalSurfaces
Al Li +
O
O
OO
O
O
Al
AlLi +Al
H HO
OH
H HOHH
O
OH O
O
OO
O
OH HO
H HO
H HO
OH
OLi +Li +
O
O
OO
O
OO
Li +
Li +
H HO
OH
H HO
H HO
H HO
H HO
H HO
OH OH
Si
Si Si
SiAlSiSiSi
SiSi Si Si
Si
Si
Si
Si
SiAl
ReAl
Si
Si
Si
Bulk Zerodur
Bulk Zerodur
RigidJoint
Interface
OriginalSurfaces
Al Li +
O
O
OO
O
O
Al
AlLi +Al
H HO
OH
H HOHH
O
OH O
O
OO
O
OH HO
H HO
H HO
OH
OLi +Li +
O
O
OO
O
OO
Li +
Li +
H HO
OH
H HO
H HO
H HO
H HO
H HO
OH OH
Si
Si Si
SiAlSiSiSi
SiSi Si Si
Si
Si
Si
Si
SiAl
ReAl
Si
Si
Si
Bulk Zerodur
Bulk Zerodur
RigidJoint
Interface
OriginalSurfaces
0
2
4
6
8
10
12
14
Heat Treatment Temperature (C)25 60 90
Mon
olith
ic G
lass
120None0
2
4
6
8
10
12
14
Heat Treatment Temperature (C)25 60 90
Mon
olith
ic G
lass
120None0
2
4
6
8
10
12
14
Heat Treatment Temperature (C)25 60 90
Mon
olith
ic G
lass
120None0
2
4
6
8
10
12
14
Heat Treatment Temperature (C)25 60 90
Mon
olith
ic G
lass
120None
Aqueous based low-temperature bonding
SCHOTT North America, Inc. Interfaces in Functional Materials
Glass and glass-ceramic sealing materials
High overpressure tolerance
Good high-CTE match
Metal / glass-ceramic chemical reaction
SCHOTT North America, Inc. Interfaces in Functional Materials
Bubble interfaces as nucleation sites- curiosity or more widespread?
Davis and Ihinger (1998)
Lithium disilicate composition
SCHOTT North America, Inc. Interfaces in Functional Materials
Piezoelectric glass-ceramics (SCHOTT)
0.5 mm
• Strong crystalline alignment
• Non-ferroelectric (polar)
Li2Si2O5 - B2O3 system
R.E. Newnham, PSU
SCHOTT North America, Inc. Interfaces in Functional Materials
Piezo resonance results
Faint resonance still detected
Polar
Li2Si2O5 - B2O3 system
35 mm disks
No resonance detected
Ferroelectric
NaNbO3 – SiO2 system
SCHOTT North America, Inc. Interfaces in Functional Materials
Prasad et al. (2002)
Ferroelectric glass-ceramic: SBN + Li2B4O7
SCHOTT North America, Inc. Interfaces in Functional Materials
-15
-10
-5
0
5
10
15
-800 -600 -400 -200 0 200 400 600 800
BST 50/50 Glass
Pola
rizat
ion
(µC
/cm
2 )
Electric Field (kV/cm)
BST50/50 Glass
-15
-10
-5
0
5
10
15
-800 -600 -400 -200 0 200 400 600 800
BST 50/50 "Hazy" Glass
Pola
rizat
ion
(µC
/cm
2 )
Electric Field (kV/cm)
BST50/50 “Hazy” Glass
-15
-10
-5
0
5
10
15
-800 -600 -400 -200 0 200 400 600 800
BST 50/50 "Hazy" Glass
Pola
rizat
ion
(µC
/cm
2 )
Electric Field (kV/cm)
BST50/50 “Hazy” Glass
-15
-10
-5
0
5
10
15
-800 -600 -400 -200 0 200 400 600 800
BST 50/50 1200°C/2hrs
Pola
rizat
ion
(µC
/cm
2 )
Electric Field (kV/cm)
BST50/50 Glass-ceramic
-15
-10
-5
0
5
10
15
-800 -600 -400 -200 0 200 400 600 800
BST 50/50 1200°C/2hrs
Pola
rizat
ion
(µC
/cm
2 )
Electric Field (kV/cm)
BST50/50 Glass-ceramic
Hysteresis due to interfacial polarization (alk.-niobate gc’s)
Ming-Jen Pan, NRL
GlassBST
0.01cm0.01cm
Area = 1 cm2
GlassBST
0.01cm0.01cm
Area = 1 cm2
Glass
BST
Glass
BST
How best to model?
SCHOTT North America, Inc. Interfaces in Functional Materials
Alkali-niobate-silicate glass-ceramics (1)
TEM micrographs courtesy of M. Lanagan and G. Yang (PSU) and Ming-Jen Pan (NRL)
As-quenched glass
SCHOTT North America, Inc. Interfaces in Functional Materials
TEM micrographs courtesy of M. Lanagan and G. Yang (PSU) and Ming-Jen Pan (NRL)
Alkali-niobate-silicate glass-ceramics (2)
20 nm
Residual glass
5 nm
SCHOTT North America, Inc. Interfaces in Functional Materials
Key Questions Review (1)
What has been the role of interfaces in the development of
emerging applications (for glass-ceramics)?
Somewhat taken for granted to date with the exception
of special “tough” glass-ceramics (e.g., amphibole-
bearing…)
SCHOTT North America, Inc. Interfaces in Functional Materials
With regard to applications, what aspects of interfaces are most
important and why?
Structural integrity
Impact on optical scattering
Effect on electrical properties
Key Questions Review (2)
SCHOTT North America, Inc. Interfaces in Functional Materials
What are the scientific issues that require basic understanding of
interfaces in glass-ceramics? (What is the relative importance of
each?)
Stress environment in high-crystal fraction glass-ceramics and means
by which to control/predict
Quantitative optical scattering models for “non-dilute” glass-ceramics
Advanced techniques (e.g., impedance spectroscopy) to investigate
electrical properties of complex glass-ceramics in light of structure-
property relations to design superior materials
Key Questions Review (3)
SCHOTT North America, Inc. Interfaces in Functional Materials
What properties of glass-ceramics hold promise for the future?
Good Question!
Key Questions Review (4)
Mechanical (e.g., ballistic performance)
Optical (e.g., a more measured look at gc lasers, etc)
Electrical (true competitors to well-known, low-cost
ceramics?)
