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PROPERTIES of QUARTZ & SILICA
Chemical composition
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The table below indicates the results of measurements, performed by various analytical techniques and instruments. Spectrometric analyses and atomic absorption measurements do provide reliable data regarding the purity of the material. However, because some of the methods are destructive, expensive and time consuming the manufacturers of the materials are performing these test periodically on randomly selected batch of material only.
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Chemical impurities
in units of ppm (parts per million).
Absence of numbers indicates that, either the element is not present or no measurement was taken at the time.
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| ELEMENTS |
PT
ID |
FUSED QUARTZ |
FUSED SILICA |
Electric
Fused |
Flame
Fused |
Standard |
Semi Dry |
Dry |
Very Dry |
| Hydroxil |
OH
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5.000
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180.000
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1,200.000
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700.000
|
100.000
|
10.000
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| Aluminum |
Al
|
14.000
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9.000
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0.100
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0.020
|
0.001
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0.001
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| Antimony |
Sb
|
0.003
|
- |
0.004
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- |
- |
-
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| Arsenic |
As
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0.002
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- |
- |
- |
- |
- |
| Barium |
Ba
|
- |
- |
- |
- |
- |
- |
| Bismuth |
Bi
|
- |
- |
- |
0.040
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- |
- |
| Beryllium |
Be
|
- |
- |
- |
0.030
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- |
- |
| Bromine |
Br
|
- |
- |
- |
0.002
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- |
- |
| Boron |
B
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0.200
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- |
- |
1.000
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- |
- |
| Cadmium |
Cd
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0.010
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- |
- |
0.080
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- |
- |
| Calcium |
Ca
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0.400
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0.600
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0.100
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- |
> 0.001
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> 0.001
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| Chlorine |
Cl
|
- |
- |
- |
- |
- |
- |
| Chromium |
Cr
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0.050
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- |
- |
0.006
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> 0.001
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> 0.001
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| Cobalt |
Co
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- |
- |
- |
0.001
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> 0.001
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> 0.001
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| Copper |
Cu
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0.050
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0.030
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0.010
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- |
> 0.001
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> 0.001
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| Gallium |
Ga
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- |
- |
- |
0.020
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- |
- |
| Germanium |
Ge
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- |
- |
- |
0.060
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- |
- |
| Gold |
Au
|
- |
- |
- |
0.001
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- |
- |
| Hafnium |
Hf
|
- |
- |
- |
- |
- |
- |
| Iron |
Fe
|
0.200
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0.400
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0.050
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0.200
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> 0.001
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> 0.001
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| Lithium |
Li
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0.600
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0.200
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0.050
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0.210
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> 0.001
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> 0.001
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| Magnesium |
Mg
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0.100
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- |
- |
- |
> 0.001
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> 0.001
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| Manganese |
Mn
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0.050
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- |
- |
- |
- |
- |
| Molybdenum |
Mo
|
- |
- |
- |
- |
- |
- |
| Nickel |
Ni
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0.100
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- |
- |
- |
> 0.001
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> 0.001
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| Phosphorus |
P
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0.200
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- |
- |
- |
- |
- |
| Potassium |
K
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0.060
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0.200
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0.050
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- |
> 0.001
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> 0.001
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| Silver |
Ag
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- |
- |
- |
- |
- |
- |
| Sodium |
Na
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0.700
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0.600
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0.050
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0.023
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>0.001
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>0.001
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| Strontium |
Sr
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- |
- |
- |
- |
- |
- |
| Thallium |
Tl
|
- |
- |
- |
0.050
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- |
- |
| Titanium |
Ti
|
1.100
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- |
- |
- |
> 0.001
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> 0.001
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| Uranium |
U
|
- |
- |
- |
- |
- |
- |
| Zirconium |
Zr
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0.800
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- |
- |
- |
- |
- |
| Zinc |
Zn
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- |
- |
- |
- |
> 0.001
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> 0.001
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NOTE: Hydroxil species in the material are exhibiting high IR absorption which provides a reliable base to calculate the OH content of the wafer. |
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Permeability
Quartz and Silica are impermeable for most gases. Although, Hydrogen, Deuterium and Helium does diffuse through at elevated temperatures under special processes and conditions.
The permeability constant is estimated to be approximately;
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@600oC /cc/sec./cm2/mm/cm.Hg
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Helium =
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2.192 x 10-8 |
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Deuterium =
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1.812 x 10-9 |
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Hydrogen =
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2.110 x 10-9 |
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Chemical Durability.
Quartz and Silica has exceptional durability properties against most chemicals. Exposure to chemicals will not cause visible surface change or damage.
There are two exceptions.
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HF (40% solution), etching rate:
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=13,000 Angstrom / min. |
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NaOH (30% solution), etching rate:
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=5.8 Angstrom / min. |
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All others, etching rate:
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= />1.0 Angstrom /min. |
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Reactivity of Quartz and Silica Toward Other Materials.
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Metals
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Gases
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Salts
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Oxides
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Mg, Al
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Reaction @ 600oC |
No reaction |
BaCl2
BaSO4
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Reaction |
CaO
CuO
Fe2O3
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Reaction over 800oC |
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KF
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Strong Reaction |
Al2O3
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Reaction over 800oC |
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Si
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Low Reaction |
KCL
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Rapid devitrification @ high temp |
PbO
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Strong reaction |
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