Transparent glass - ceramics Edgar D. Zanotto Vitreous Materials Lab Federal University of São Carlos, Brazil www.lamav.ufscar.br Presented at the IMI-NFG US-Japan Winter School , Jan 14, 2008 and Reproduced by the International Materials Institute for Glass for use by the glass research community; Available at: www.lehigh.edu/imi
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OUTLINE
Introduction to glass-ceramics Brief literature review on TGC Potential applications of TGC Conditions for transparency Mature TGC – nanocrystals New TGC: Properties
Sintered aluminate GC IR transmitting CG Ce: YAG GC for lighting Laser crystallized GC PTR GC LGHC GC
Opt & Mech Opt & Mech Opt Opt Opt & Mech Opt & Mech
Surprise.... Conclusions
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Glass-ceramic synthesis
Entropy vs. T plot Heat-treatment plot
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INTRODUCTION null porosity
controlled volume crystallization
designed microstructures: size & shape & GLASS-CERAMICS uniform grain size, % crystallinity, high thermal and etc. chemical stability tougher than glasses
reproducible properties
optical transparency
interesting electrical properties Vitreous Materials Lab – www.lamav.ufscar.br
INTRODUCTION Applications of transparent glass-ceramics
Thermo-mechanical
Optical (potential)
Cooking ware Fire resistant plates Security windows Telescope mirrors…
saturable absorber media; illumination devices using IR; heat-resistant materials that absorb UV, that reflect infrared and are transparent to visible light; that absorb UV and fluoresce in red/IR; second harmonics generating; substrates for LCD devices; optical amplifiers for up-conver; substrates for arrayed waveguide grating (AWG); radiation sources of lamps; Laser pumps; Laser media; Materials for precision photolithography; ring laser gyroscopes; solar collectors; printed optical circuits; etc. Vitreous Materials Lab – www.lamav.ufscar.br
The inventor of GLASS-CERAMICS
S.D. Stookey discovering GC in the middle 1950s
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LITERATURE REVIEW- PIONEERS OF TGC STOOKEY,S.D. V Int. Congress on Glass, pp. V/1-8 1959 BORRELLI, N.F. ELECTRO-OPTIC EFFECT IN TRANSPARENT NIOBATE GLASS-CERAMIC SYSTEMS Journal of Applied Physics, 38 (11): 4243 1967 BEALL, G.H.; DUKE, D.A. TRANSPARENT GLASS-CERAMICS Journal of Materials Science, 4 (4): 340 1969 Recent articles in the next slide Vitreous Materials Lab – www.lamav.ufscar.br
LITERATURE REVIEW (TGC title )
YEAR
1967 1969 1978 1982 1984 1985 1986 1987 1988 1993 1994 1995 1996 1998 1999 2000 2001 2002 2003 2004 2005
1 2 3 3 2 2 5 3 2 2 2 4 5 8 5 7 9 11 5 20 5
2006
5
112 ISI papers
Derwent II ~90 patents
Corning Schott Nippon Others
25 20 15 10 5
30 years
0 1960
1980
2000
2020
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Crystalline phases in TGC
Β−quartz ss Β-eucriptite Mullite Spinel Willemite Ghanite Forsterite β-BBO LiNbO3 NaNbO3 PbF2 LaF3 ZnO Etc.
Most TGC have nanosize crystals & small crystallized volume fraction (~ 50% or less) Vitreous Materials Lab – www.lamav.ufscar.br
THEORY Light attenuation
atomic absorption (β) surface reflection (R)
+ scattering (S)
scattered light
Io
Reflection losses (%) Transmitted light
10
reflected light
reflected light
fluorescence
I = I o (1 − R ) 2 exp(−( β + S ) x) ⎛ n −1 ⎞ R=⎜ ⎟ ⎝ n +1⎠
12
2
8
R
Incident light
6 4 2 0 1
1.2
1.4
1.6
1.8
2
n
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Conditions for transparency Transparent glass-ceramics
crystal size > Tx
0.6 W
Temp. < Tx 50μm
J. Am. Ceram. Soc. 88 (2005) 989
Refractive index change
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Laser crystallization in São Carlos C. A. C. Feitosa, L. J. Q. Maia, A. L. Martinez, A. C. Hernandes, Valmor R. Mastelaro,
IFQSC, University of São Paulo, São Carlos, Brazil Vitreous Materials Lab – www.lamav.ufscar.br
40BaO - 45B2O3 - 15 TiO2 (BBT) Microstructures from two crystallization processes
BBT glass after irradiation with CO2 laser (λ= 10.6 μm) 4 min, 40 W/cm2. = 10,000 J/cm2 Glass at 300oC (Tg = 580 oC)
BBT GC in resistive furnace at 620oC.
Mastelaro et. al.
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Surface crystallization of BBT glass Vidros 4% e 15% # (006)
* BaTi(BO3)2 # β-BBO
* (009)
* (003)
Intensidade (u.a.)
* (006)
15% de TiO2
# (104) # (006)
20 μm
4% de TiO2
10
20
30
40
50
60
2 θ Graus
It is possible to produce policrystalline lines. 5 μm
200 μm
Details; crystals within the line and diffraction pattern Mastelaro et. al.
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SHG in partially crystallized BBT glass Mastelaro et. al.
Laser beam Nd:YAG (λ = 1064 nm)
Second harmonic generation Vitreous Materials Lab – www.lamav.ufscar.br
PTR Glasses Oxy fluor bromide glasses S.D. Stookey et al. (1954) – Corning, USA L.B. Glebov et al. (1990) - Vavilov SOI, Russia + Creol/ UCF, USA
Composition
Major: SiO2, Na2O, ZnO, Al2O3
Minor: K2O, F, Br
Dopants (~200 ppm): Ag, Ce, Sb, Sn
Impurities ( < 2 ppm): transition metals Vitreous Materials Lab – www.lamav.ufscar.br
PTR glass is a F-Br sodium-zinc-aluminumsilicate glass doped with Ag, Ce, Sn and Sb
Ce4+
hν 3+
Ce
Current technology at UCF/CREOL - optical quality PTR glasses with aperture up toVitreous 50 mm.Materials Lab – www.lamav.ufscar.br
e-
Mechanism of photo-thermo-crystallization
Ce4+
hν 3+
Ce
e-
Ce4+
Valence change Photoionization
Valence change
kT
hν Ce3+
e
-
Ag+
Ag0
Electron Trapping
Latent Image
Ag0
Ag0 kT
UV excitation
kT
Ag0
Ag0
Ag0
Ag0
kT
Silver atoms diffusion
Sodium fluoride crystal
kT
Growth of Silver nanocrystal
Na+
Silver nucleation center
kT
Ag0 Ag0 Ag0 Ag0
Ag0
kT
kT
F
-
Na+
F
F F
-
-
Na+ F
-
Ag0 Ag0 Na
+
F
-
kT F
Na+
Ag0 Ag0
-
Na+ -
Na+ F
-
kT Na+
3D image (hologram) of object is transformed to the phase pattern (refractive index variations) caused by selective NaF crystal distribution in accordance with the UV intensity distribution in glass interior.
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.
PTRG (only the active ions are shown) Proposed mechanism of photo induced crystallization
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University of Central Florida School of Optics - CREOL Laboratory of Photo-Induced Processes
Ce4+
hν Ce3+
Absorption spectrum of photo-thermo-refractive glass
Absorption, cm
-1
2
HF 2.7 μm
COIL Nd, Yb, Er 1-1.6 μm
1.5 1 0.5
DF 3.6-4.2 μm
0 0
1000
2000
3000
4000
Wavelength, nm
No detectable absorption in the range of 1 μm Absorption of hydroxyl in theMaterials range ofLab 4 μm Vitreous – www.lamav.ufscar.br
e-
PTR glasses S.D. Stookey et. al. Corning’s Fotalite Creol’s PTRG Hologram Leon Glebov et. al.
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LARGE GRAIN, HIGHLY CRYSTALLINE, HIGHLY TRANSPARENT GC T. Berthier, V.M. Fokin, E.D. Zanotto LaMav- Federal University São Carlos, Brazil Vlad Fokin
Thiana Berthier
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STRATEGY Simultaneous compositional variation of solid solution crystals and glassy matrix decreases Δn New type of transparent glass-ceramic small or large grain size
high crystallized volume fraction Vitreous Materials Lab – www.lamav.ufscar.br
OPTICAL PROPERTIES Crystal morphology Transmission Spectra 200 nm – 1100 nm
Grain size Degree of crystallinity OM
Transmittance measured for different sample thicknesses Estimated parameters (P1 and P2):
I = P1 exp(− P2 x ) I0
P1 = (1-R)2 P2 = (β+S)
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MICROSTRUCTURES The crystals are solid solutions: TA4+2xAE4-x[GF6O18] (0 ≤ x ≤ 1) T = trace element
Their morphology can vary from
A = alkali
J, spherical to
V8, cubic
AE = alkaline earth GF = Si, P, B
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TRANSMITTANCE Morphology Distinct crystal shapes
Different transmittances V8, cubic 5-6 μm J, spherical 7-8 μm
crystal/crystal Interfaces are quite different for spherical and cubic crystals
Best transmittance
Cubic crystals Vitreous Materials Lab – www.lamav.ufscar.br
TRANSMITTANCE
Grain size
glass J, spherical crystals, ~42% crystallized I(λ) dependence
Crystal size
Affects P2 * Same crystalline fraction
Importance of thermal history
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TRANSMITTANCE glass V8, cubic crystals (3-5 μm)
Degree of crystallinity
Glass V8 & T6, maximum transmission for ~ 9597% OM crystallinity
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The beasts! Transparency of 4 mm thick specimens Glass
GC 97% crystallinity
50% crystallinity
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DISCUSSION 1.64 18
1.62
crystals glassy matrix 16
n
CA, at%
crystal
1.60
1
1.58
14
12
2
glass phase
10 0,0
1.56
0,2
0,4
α
0,6
0,8
1,0
alkali content in
1.54 5
10
15
20
25
30
Alkali oxide, wt%
35
crystals 30% > glassy matrix
EDS measurements Vitreous Materials Lab – www.lamav.ufscar.br
DISCUSSION
High crytallized fraction
reduced crystal / glass interface
Simultaneous variations of the glass-matrix and s/s-crystal compositions during crystallization
refractive indexes of crystal and glass verge
Main reasons for improved transparency in these new TGC Vitreous Materials Lab – www.lamav.ufscar.br
Mechanical
behaviour of HCHTGC
A new, specially designed, method of impact testing! Vitreous Materials Lab – www.lamav.ufscar.br
Impact testing of glass Courtesy of Leo Siiman, Creol/ UCF
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Don’t
try this experiment in your lab! Vitreous Materials Lab – www.lamav.ufscar.br
Kic versus volume fraction crystallized Anstis Average grain size from 3 to 6 um
⎛E K IC = 0.016 ⎜ ⎟ ⎝H⎠
F 3 c2
Kic Anstis Kic Niihara kic Anstis (Thiana) Kic Niihara (Thiana)
1.5
c
1/2
Kic (MPa. m )
1 ⎞2
Eglass 71 GPa
1.0
Nihara 2 1 − − ⎛ l ⎞ 2⎛ H ⎞ 5⎛ H
a⎞ ⎜ ⎟ ⎟ ⎜ kic 0 , 035 = ⎜ ⎟ Ecr ~105 ⎟ ⎜ ⎜ ⎝a⎠ ⎝ Eφ⎠ ⎝ φ ⎟⎠
0.5
0
20
40
60
Fr. cristalizada (%)
80
100
φ~3, a,l,c [um]
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Why
do the transparency and impact strength drop significantly for > 97% crystallinity?
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SPONTANEOUS CRACKING for > 97% crystallinity! accelerated 300X
.
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CONCLUSIONS - highly transparent in the visible ~ 90% for 1mm New type of TGC
- nm to μm grain size - up to 97% crystallized volume fraction - chemical durability OK - good mechanical properties, which can probably be much improved by ionexchange. - can be drawn into fibers - luminescence ? doping with Cr and RE ions should be tested... Vitreous Materials Lab – www.lamav.ufscar.br
On the origem of misterious biomorphs and geoglyphs in Nazca, Peru, 200 B.C. .
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Sm2O3-Bi2O3-B2O3 glass SmxBi1-xBO3 crystal
SHG
Crystals
Courtesy of T. Komatsu
Bird in Nazca, Peru
300 μm
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VITREOUS MATERIALS LAB, UFSCar, São Carlos BRAZIL
Thank you!
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