SCHOTT North America, Inc. Interfaces in Functional Materials

Practical aspects and implications of interfaces in -ceramics

Mark J. Davis SCHOTT 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 Practical Effects (Internal) ƒ Microstructural development ƒ surface energies and their impact on nucleation ƒ general glass stability; controlled vs. un-controlled crystallization (i.e., critical cooling rate in a commercial setting vs. academic…) ƒ Structural ƒ detailed nature of interface (e.g., “pristine”, microcracked…) ƒ crack blunting processes ƒ residual stresses, crystal clamping ƒ permeability ƒ Electrical ƒ Effective connectivity ƒ Resistive / capacitive behavior ƒ Optical ƒ scattering effects SCHOTT North America, Inc. Interfaces in Functional Materials

Practical Effects (External)

ƒ Joining (low-temperature) ƒ Hydrophilic vs. hydrophobic surfaces ƒ Competitive bonding technologies ƒ Glass-to-metal sealing (high-temperature) ƒ Flow vs. crystallization “stiffening” ƒ Interfacial reactions ƒ Hermeticity (CTE matching) ƒ Polishing ƒ Crystal vs. glass effects (mostly proprietary know-how) SCHOTT North America, Inc. Interfaces in Functional Materials

Why glass-ceramics? ƒ Single Crystals often exhibit the highest property performance, but are generally more difficult and expensive to manufacture ƒ Ceramics are easier to manufacture, but are typically porous to some degree and may exhibit inhomogeneities, aging, decreased strength, etc. ƒ take advantage of processing ease, homogenization efficiency, and tailorable compositions, but lack certain functions (e.g., novel CTE combinations, lack of center-of-symmetry) ƒ 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 , 2nd- harmonic generation, piezoelectricity) SCHOTT North America, Inc. Interfaces in Functional Materials How is a commercial glass-ceramic produced?

Melting

Ceramization

Inspection g la s s - c e r g a la m ss ic SCHOTT North America, Inc. Interfaces in Functional Materials Thermal expansion tailoring

Aluminum

Mic rocrac king a Same composition for all curves nd hys teresis

From Sect. 6.5, Glass-Ceramics for Optical Applications, M. Davis in Optical Materials and Their Applications, Springer-Verlag SCHOTT North America, Inc. Interfaces in Functional Materials Examples of SCHOTT glass-ceramics

Ring-laser gyroscopes

8.2 m telescope mirror blanks

Glass-ceramic cooktops

Pressed glass-ceramic reflectors SCHOTT North America, Inc. Interfaces in Functional Materials LargeLarge mirrormirror blankblank productionproduction (Zerodur)(Zerodur) VLT telescope in Chile (8.2 m mirrors with adaptive )

On the road to Cerro Paranal, Chile

Zerodur mirror fabrication

(www.eso.org) SCHOTT North America, Inc. Interfaces in Functional Materials Typical LAS (Zerodur) glass-ceramic microstructure Non-isothermal ~2 oC/hr

Internal surface area ~ 30 m2/gm

~1022 m-3 HQSS crystals

25 -3 ~10 m ZrTiO4 crystals

~50 nm high-quartz solid-solution crystals

bar = 200 nm

Maier and Muller, 1987 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

Fu sed S * ilica

Py rex * /Du * ran Zer od ur *

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 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

Scattering example in glass-ceramics (DWDM substrate)

small particle limit: 4a3 1 τ = (n⋅Δn)2 ρ 3 λ4 Rayleigh (1881)

Visible light only (IR blocking filter KG3) λ < 850 nm

Sample thickness ~ 35 mm Crystal size ~35 nm IR only (visible blocking filter RG 1000) λ > 850 nm SCHOTT North America, Inc. Interfaces in Functional Materials Quantitative scattering example in glass-ceramics (Zerodur)

λ-8 dependence

λ-4 dependence

From Sect. 6.5, Glass-Ceramics for Optical Applications, M. Davis in Optical Materials and Their Applications, Springer-Verlag SCHOTT North America, Inc. Interfaces in Functional Materials

Crystal clamping of a FE phase (Lynch and Shelby 1984) Also Grossman and Isard (1969)

Expected behavior No crystal clamping

Crystal clamping

Assuming ~1% strains and E ~ 260 GPa, Glass calculated residual stresses ~ 3 GPa (!)

PbTiO3 SCHOTT North America, Inc. Interfaces in Functional Materials

Residual stress studies (crystal/glass interface)

System Max |σ|(MPa) Source

Li2O-2SiO2 ~150 Mastelaro and Zanotto (1999)

Soda-lime silicate ~200 Mastelaro and Zanotto (1996)

LAS ~400 Zevin et al. (1978)

PbTiO3 –BaO–B2O3 ~3000 (?) Estimated from data of Grossman and Isard (1969)

⇒ In all cases, calculated stresses >> nominal 20 MPa tensile strength of typical (imperfect) external glass surfaces SCHOTT North America, Inc. Interfaces in Functional Materials Engineered microstructure examples (G. Beall)

Fluorrichterite

¾ High Crystallinity Canasite ¾ Interlocking Crystals ¾ Grain-size from 1-10 μm

¾ Acicular Crystals (Rods) Enstatite ¾ Bladed Crystals (Laths) ¾ Polysynthetic Twinning SCHOTT North America, Inc. Interfaces in Functional Materials Aqueous based low-temperature bonding

Chemisorbed Physisorbed

Bulk Zerodur

O O

O O

HH HH

H H H

H H

O

H O H H O O O +

H H H

H H H H H H H Li H

H O HH O Al Si H

O H O Al Si Si Si Si Si

O O H H

H H O

H H

H O

H O H H O H O O O O O O

H O O O H OHOH O

O O O O H +

O O H Li H Si

O Original Si Al O O Re O O O Si Rigid HH HH

HH + O

Si Si Al Si Si Hydrophilic O HHH H OLi H H H H + + O O Si O O O Li O Si Al O O Li Joint + Surfaces O H O O

Li O O O O O Surface Si Si H H H H Si H H H Si H H

O O + Al O H Interface

H H O H

Li H + H

O O

Li O O O O H H O O Si O O O Al Si Si Si Al Si Si Al O O O Si Si Al Si Al Si Si Al Li + Bulk Zerodur Bulk Zerodur

14

Bulk Zerodur 12 Li +

+

Li Al Si Al 10

O

Al O Si Si

O

Si O

O O O O O O Al O

O O OH

H H H H H H O H O H H

H H 8

O O O

H H H

- + O H O -

OH Li O Si OH

O

O Si OH 6

OH HH

HH OH

O

+ OH O

H H H H H Original H H OH- Li + 4 O O Glass Glass Glass Glass Monolithic Monolithic Monolithic Monolithic O Inorganic Si O O + OH O Li Surfaces OH Si O Si

OH- O OH O Joining 2

OH O O O

OH Si O H H H H H OH H Liquid Si O H + H H O O OH H Li O + 0 OH O OH- H None 25 60 90 120

HO H

H H

H H

H H

O

H H O H Heat Treatment Temperature (C) O

H O OHOH O

O O O O O O O Si Al Si Si Al Si Si Si Li + Bulk Zerodur 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)

Li Si O -BO system 2 2 5 2 3 0.5 mm

• Strong crystalline alignment • Non-ferroelectric (polar)

R.E. Newnham, PSU SCHOTT North America, Inc. Interfaces in Functional Materials

Piezo resonance results 35 mm disks

Ferroelectric Polar

Faint resonance still detected

No resonance detected

Li Si O -BO system 2 2 5 2 3 NaNbO3 –SiO2 system SCHOTT North America, Inc. Interfaces in Functional Materials

Ferroelectric glass-ceramic: SBN + Li2B4O7

Prasad et al. (2002) SCHOTT North America, Inc. Interfaces in Functional Materials

Hysteresis due to interfacial polarization (alk.-niobate gc’s)

Ming-Jen Pan, NRL

BST 50/50 Glass BST 50/50 "Hazy" Glass BST 50/50 1200°C/2hrs 15 15 15 BST50/50 Glass BST50/50 “Hazy” Glass BST50/50 Glass-ceramic 10 10 10 ) )) )) 2 22 22 5 5 5

0 0 0

-5 -5 -5 Polarization (µC/cm Polarization (µC/cm (µC/cmPolarization Polarization PolarizationPolarization (µC/cm (µC/cm

-10 -10 -10

-15 -15 -15 -800 -600 -400 -200 0 200 400 600 800 -800 -600 -400 -200 0 200 400 600 800 -800 -600 -400 -200 0 200 400 600 800 Electric Field (kV/cm) Electric Field (kV/cm) Electric Field (kV/cm)

Area = 1 cm2 Glass

0.01cm GlassGlass BST 0.01cm BSTBST How best to model? SCHOTT North America, Inc. Interfaces in Functional Materials Alkali-niobate-silicate glass-ceramics (1)

As-quenched glass

TEM micrographs courtesy of M. Lanagan and G. Yang (PSU) and Ming-Jen Pan (NRL) SCHOTT North America, Inc. Interfaces in Functional Materials Alkali-niobate-silicate glass-ceramics (2)

Residual glass

20 nm

5 nm

TEM micrographs courtesy of M. Lanagan and G. Yang (PSU) and Ming-Jen Pan (NRL) SCHOTT North America, Inc. Interfaces in Functional Materials

Key Questions Review (1)

ƒ 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

Key Questions Review (2)

ƒ With regard to applications, what aspects of interfaces are most important and why?

¾Structural integrity

¾Impact on optical scattering

¾Effect on electrical properties SCHOTT North America, Inc. Interfaces in Functional Materials Key Questions Review (3)

ƒ What are the scientific issues that require basic understanding of

interfaces in glass-ceramics? (What is the relative importance of

each?)

¾Stress environment in high-crystal fraction glass-ceramics and means by which to control/predict

¾Quantitative optical scattering models for “non-dilute” glass-ceramics

¾Advanced techniques (e.g., impedance spectroscopy) to investigate electrical properties of complex glass-ceramics in light of structure- property relations to design superior materials SCHOTT North America, Inc. Interfaces in Functional Materials

Key Questions Review (4)

ƒ What properties of glass-ceramics hold promise for the future?

Good Question!

¾Mechanical (e.g., ballistic performance)

¾Optical (e.g., a more measured look at gc lasers, etc)

¾Electrical (true competitors to well-known, low-cost ceramics?)