溶凝膠法製做玻璃

Si

OR

OR

OR

RO + H2O Si OR

OR

HO + ROH

OR

Si

OR

O

OR

RO+Si

OR

OH

OH

RO Si

OR

OR

OR

HO Si

OR

OR

OR

+ H2O

溶凝膠法的過程與原理 : 以 SiO2 為例

TMOS(Si(OCH3)4)+ 水 + 醇

(a) 水解 (hydrolysis) 反應

(b) 縮合 (condensation) 反應

(c) 多縮合反應 (polycondensation)

Si

OH

O

HO

HO Si

OH

OH

HO

+ 6(H2O)

+ 6Si(OH)4

SiO

O

O

O SiO

O

O

SiOH

OH

OHSiOH

OH

HO

Si OH

OH

HOSiHO O

HOH

Si

OHOH

OH

Si

OH

HO

HO

聚合反應

單體(monomer)

顆粒(particle)

鏈狀結構(chain)

三維網狀結構(3D network)

不同環境下的聚合反應

(1) Far from gel point

(2) Near from gel point

(3) Gel point

(acid-catalyzed)

10nm

(base-catalyzed)

10nm

溶凝膠過程與溫度之關係

xerogel film

heatdense film

dense ceramics

heat

xerogel

aerogel

Metal alkoxide solution

evaporation

evaporation of solvent

coating

gelling

wet gel

uniform particle

precipitating

spinningceramic fiber

hydrolysiscondensation

sol

furnace

coat

ing

溶凝膠的不同製程與結果

溶凝膠法的優缺點 優點：(1) 均質性與高純度。(2) 節省能源，減少蒸發的損失與空

氣的汙染、較純的樣品、避開相

變、結晶的過程。缺點：(1) 原料昂貴。(2) 凝膠的收縮量大。(3) 殘留孔穴、氫氧基、碳。

影響成膠時間的因素 1. 溶液酸鹼值 2. 溫度 3. 矽前驅物與水的莫耳比 4. 矽前驅物的分子量 5. 醇類與水的體積比 6. 其他溶劑與添加物

solvent gelling time (hrs)

Methanol (CH3OH)

Formamide( 甲醯胺 ,HCNOH2)

Dimethyl-formamide( 二甲基甲醯胺 , C3H7CNO) Acetonitrile( 甲基氰 , H3CCN)

Dioxane( 二氧六環 , C4H8O2)

8

6

28

23

41

熟化過程 (Aging process)

acid-catalyzed

base-catalyzed

particulate silica gels high solubility

particulate silica gels low solubility

緻密化 (Densification)

Flow Chart of the two methods used to vary the pore characteristics of the gel silica matrices

Alumina gel

ORMOSILS (Organically Modified Silicates)

Si(OR)4+R2Si(OR)2+yR′Si(OC2H5)3

where R is alkyl( 烷基 ) group( -CH3), R′ is alkylene group( 烯烴基 -(CH2)n), y is organofunction group such as -(CH2)3NH2, -(CH2)3NHCOONH2, - (CH2)3S(CH2)2CHO.

Basic NMR Interactions in SolidsNMR: Nuclear Magnetic Resonance

The Hamiltonian of the interaction of the nucleus with external magnetic field B0 and its environment:

H=HZ + HQ + HC + HD

Where HZ is the Zeeman interaction, HQ is the quadrupole interaction, HC is the chemical shift interaction, and HD is the magnetic dipole-dipole interaction.

π2/Bγ=νfrequency resonanceI- 1,+I- , 1,-I -I,=m where,mBγ-=E

B•μ-=H

00

0

0Z

ninteractio Zeeman

原子核種 自旋 自然界含量 (%) 磁場 7T時的共振頻率 (MHz)

1H 1/2 99.9 300.16Li7Li

13/2

7.692

44.1116.6

10B11B

33/2

19.980.1

32.296.3

17O 5/2 0.038 40.727Al 5/2 100 78.229Si 1/2 4.7 59.631P 1/2 100 121.451V 7/2 99.7 78.9

69Ga71Ga

3/23/2

6040

72.091.5

FT

FT

Quadruploe interaction- first order

1)≤η≤(0parameter asymmetry theis η and1)-I2(I2

Q3=νconstant coupling quadrupole thewhere

)2

1-m](φ2cosθsinη

2

1-1)-θcos3(

2

1[ν-ν=ν

ccQ

22Q01-m↔m

First order quadrupole powder pattern for spin I=3/2

Quadrupole Interaction- second order

Second order quadrupole powder pattern for central transition of a spin I=3/2

.φ2cosη8

3-φcos2η

4

1+η

3

1+

8

3-=)φ(C

,φ2cosη4

3+φcos227+η

2

1-

8

30-=)φ(B

,φ2cosη8

3-φcos2η

4

9-

8

27-=)φ(A

],4

3-)1+I(I[ν=R where

)]φ(C+θcos)φ(B+θcos)φ(A[ν6

R-ν=ν

222

222

22

2Q

24

00/21↔1/2-

電腦模擬參數QCC Qcc η Weight(%)

BO3 2.55MHz 180KHz 0.15 0 60.4

BO4 0.2MHz 0 0.1 0 39.6

27Al MAS spectrum of 9Al2O3-2B2O3

B0=40T

11B MAS spectrum of borosilicate glassB0=14.1T

4Si

3Si+1B

Chemical shift interaction

. field magnetic external theis B and

or,shift tens chemical theis σ momentum,angular -spin theis I where

B•σ•Iγ=H

0

0CS

Chemical shift powder pattern

).σ-(σ2

1=σ ),σ- σ-(2σ

6

1 =σ ),σ +σ+σ (

3

1=σ

,σ ≤ σ ≤σ that so labeled areor which shift tens chemical theof valuesprincipal theare σ ,σ ,σ and or,shift tens chemical theof axes principal the

respect to with B field theof anglespolar theare φ and θ angle thewhere

in1)--=

=

1122aniso223311ax332211iso

112233

332211

0

θcos2φ]sσ-θ(3cosσσ-[1ν

θ])cosσ-(1+φθsin)cosσ-(1+φθsin)sinσ-[(1νν2

aniso2

axiso0

211

2222

22330

).σ-1(ν=ν),σ-1(ν=ν

),σ-1(ν=ν

3303

2202

1101

Magnetic dipole-dipole interaction

]∑ )I•I-I(3Ir

)θcos3-1([γγ

4

1≈

]r

)r•μ)(r•μ(3∑ -

r

μ•μ[

2

1=H

j≠ijijziz3

ij

ij2

2ji

5ij

ijjiji

j≠i3ij

jiD

In practice, it is very difficult to carry out a calculation of the lineshape due to dipole-dipole interaction. An excellent approximation for many cases is made by using a normalized Gaussian shape function given by

).νG( of derivative theof peak width peak to the toequal is Δ2 where

]Δ2

)ν-ν(-exp[

π2Δ

1=)ν(G 2

20

7 Tesla

14 Tesla 21.1 Tesla

Strength 45 tesla

Type Hybrid

Bore size 32 mm (~1.25 inches)

Online since December 1999

Cost $14.4 million

Weight 31,752 kg (35 tons)

Height 6.7 meters (22 feet)

Operating temperature -271 ° C (-456 ° F)

Water used per minute15,142 liters

(4,000 gallons)

Power required 33 MW

The 45 Tesla Hybrid superconducting magnet of 11.5 tesla with a resistive magnet of 33.5 tesla

Magic Angle Spinning (MAS)

probe rotor

Second order quadrupole interaction

Chemical shift interaction

The structural groups of alkali silicate glasses determined from 29Si MAS-NMR(Journal of Non-Crystalline Solids 127 (1991) 53-64)

29Si MAS-NMR spectra of sodium silicate glasses.

29SI MAS-NMR spectrum of sodium metasilicate glass.

Experimentally determined Q, distribution in lithium ( ), △sodium (□) and potassium (○) silicate glasses as a function of moll% of alkali oxide. Fitted lines were calculated from equilibrium constants shown in table. , Q4; , Q3; , Q2 ； , Q1, , Q0.

Conclusion:The detailed distribution of the structural units Qn in binary silicate glasses was determined by means of the MAS-NMR technique. The equilibrium of the following types were found apparently to govern the concentrations of Qn species, 2Qn Qn-1 + Qn+1 (n = 3, 2, 1),of n = 3, 2, 1 for sodium and potassium and n = 3, 2 for lithium silicate glasses in limited composition ranges. The agreements with the thermodynamic data were quantitative in the sodium and potassium silicates but only qualitative in the lithium silicate. The chemical shift for all Qn, species depends linearly on the composition and the slopes are less for Qn, with smaller n. The linear relations between the averaged chemicalshift and the theoretical optical basicity strongly suggest the potential use of the 29Si chemical shift as a scale for the basicity of the system.

Structure of sodium aluminoborate glasses study by NMR(Solid State Nuclear Magnetic Resonance 27 (2005) 37–49)

27Al B=18.8T11B B=14.1T

17O B=14.1T

Random mixing model:In a random mixing model without any constraints.4–4 avoidance model:In this model, connections between tetrahedral network units, [4]M–[4]N (avoidance of [4]Al–O–[4]Al, [4]Al–O–[4]B and [4]B–O–[4]B species) are unfavorable, involving only trivalent cations (B and Al).

oxygen containing [5,6]Al three-coordinated

Conclusions:Details of linkages such as [4]Al–O–[4]Al, [3]O(2[5,6]Al,[4]Al), [4]Al–O–[4]B, [4]Al–O–[3]B, [5,6]Al–O–[3]B, [4]Al–O–[4]B, [4]B–O–[3]B and [3]B–O–[3]B and B-NBO can be distinguished. The fractions of oxygen species can be calculated with the knownfraction of B and Al species based on random mixing and mixing considering 4–4 avoidance (avoidance of [4]Al–O–[4]Al, [4]Al–O–[4]B and [4]B–O–[4]B species). Allof the glasses in this study show high degrees of bond regularity (higher fractions of Al–B pairs than random) resulting from the ‘‘maximum 4–4 avoidance’’. However,the significant amounts of [4]Al–O–[4]B suggests that the [4]Al–O–[4]B is energetically less unfavorable than [4]Al–O–[4]Al and [4]B–O–[4]B. A better approach to predicting the oxygen speciation for the glasses containing significant amounts of [5,6]Al involves grouping two [5,6]Al species. The result strongly suggests the presence of [3]O(2[5,6]Al, [4]Al).