Physical Characterization of Glassy Materials Using Ultrasonic Non-Destructive Technique

Sidek Ab Aziz Department of Physics, Faculty of Science Universiti Putra Malaysia 43400 UPM Serdang, Selangor

Seminar on Materials Science and Technology 2013, June 24, 2013, ITMA

General Discussion

Glass (amorphous)

Crystalline

Scope of Presentation

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What is a glass?

Glass - hard, brittle solid material that is normally lustrous and

transparent in appearance and shows great durability under

exposure to the natural elements.

Obsidian - super-heated sand or rock that rapidly cooled.

Moldavite formed by meteorite impact (Besednice, Bohemia)

4

Natural heat-producing processes like volcanoes and lightning strikes are responsible for creating various forms of natural glass.

obsidianites, kind of alumino-silicate

(SiO2–Al2O3) glasses containing

crystalline particles such as Fe2O3.).

Man-Made Glass

Principles of Glass Formation

5

Glass (amorphous) Crystalline

The viscosity increases with undercooling until the liquid freezes to a glass

Crystals ordered atomic

structures mean smaller volumes (high density) & lower energies

thermodynamically stable phase

Glasses lack of long-range

order results in larger volumes (lower density), higher energies;

thermodynamically metastable phase

Knowledge of glass structure is important which relates to other

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Silicate Borate

• Glass structure has short range order but no long range order.

• Silicate tetrahedra link up to form 3D glass network. • Some ions such as Na will modify the network but are

not part of it.

Some structural groupings in borate glasses as indicated

from nuclear magnetic resonance experiments (Bray

1985).

Small solid circles represent boron atoms, open circles

oxygen atoms and an open circle with negative sign

indicates non-bridging oxygen.

Glass Structure

Bonding Structure of Tellurite

2D chain: crystalline TeO2

TeO2 chains

Deformation and breaking of TeO2 chain by modifier

The structure

basic TeO2 –based glass structural unit namely, TeO4 trigonal

bipyramids (tbp) and TeO3 trigonal pyramid (tp) .

TeO4 tbp TeO3 tp

Both structure have a lone pair of electron in one of its

equatorial /axial sites.

7

Phosphate

Basic glass former, P2O5

Effects of Mg

cation content on

the phosphate glass

Glass Sample Preparation

www.glassforever.co.uk/howisglassmade/

glass furnace cooling systems

8

9

Some pigments used to produce coloured glass

Compounds Colors Compounds Colors

iron oxides greens, browns selenium compounds reds

manganese oxides deep amber, amethyst,

decolorizer

carbon oxides amber/brown

cobalt oxide deep blue mix of mangnese, cobalt,

iron

black

gold chloride ruby red antimony oxides white

uranium oxides yellow green (glows!) sulfur compounds amber/brown

copper compounds light blue, red tin compounds white

lead with antimony yellow

Research Project To produce the fiber optics and flat glasses for the

future applications

Glass Research @ UPM

Fiber Optics are cables that are made of optical fibers that can transmit large amounts of information at the speed of light. (www.dictionary.com)

Dominated by Silicate based glass

Glass Research @ UPM

Key Researchers

A goal of solid-state science, which intends to give universal understandings of

macroscopic properties through simple theories on the basis of known atomic

structures. 11

Glass Research @ UPM

12

Tellurite (TeO2)

Phosphate (P2O5)

Borate (B2O3)

Lithium

Chloroborate

Lead Borate

Lead Bismuth

Borate

Bismuth Borate Zink Chloride Phosphate

Silver Phosphate

Lithium Phosphate

Lithium Chlorophosphate

Lead Magnesium

Chlorophosphate

Lead Bismuth Phosphate

Lithium Chloride Phosphate

Lithium Zink Phosphate

Lead Zink Metaphosphate Zinc magnesium phosphate

Zinc Tellurite

Borotellurite

Zinc oxyfluorotellurite

Lead Borotellurite

Silver Borotellurite Zinc Neodymium

Tellurite

Zinc borotellurite

Zinc oxyfluorotellurite

Ferum Tellurite

Glass research activities conducted at the Universiti Putra Malaysia.

Formation

Physical Studies

Elastic Properties

Optical

Characterization

Thermal Properties

Dielectric Properties

Research Scope

Glass Research @ UPM

13

Tellurite (TeO2)

Phosphate (P2O5)

Borate (B2O3)

Selected some of the prepared binary and ternary glass samples at the Department of Physics, Universiti Putra Malaysia.

Ag2O-B2O3

PbO-B2O3

Bi2O3-B2O3

Li2O-P2O5

PbO-B2O3

PbCl2-P2O5

LiCl-P2O5

ZnCl2-P2O5

B2O3-TeO2

ZnO-TeO2

Fe2O3-TeO2

PbO-Bi2O3-B2O3

LiCl-Li2O-P2O5

PbCl2-MgO-

P2O5

Li2O-ZnO-P2O5

PbO-ZnO-P2O5

PbO-Bi2O3-P2O5

Cu2O-CaO-P2O5

Ag2O-B2O3-TeO2

PbO- B2O3-TeO2

ZnO- B2O3-TeO2 Nb2O5- ZnO- TeO2

AlF-ZnO-TeO2

binary

ternary

Glass Oxide Former Modifier Glass Samples Researchers

Binary Oxide Glass Series

Borate (B) Silver (Ag) Ag2O-B2O3 Sidek et al. (1994)

Lead (Pb) PbO-B2O3 Azman et al. (2002)

Bismuth (Bi) Bi2O3-B2O3 Sidek et al.(2007)

Phosphate (P) Lithium (Li) Li2O-P2O5 Low et al. (1999)

Sidek et al.(2003)

Lead (Pb) PbO-B2O3 Azman et al. (2002)

Talib et al. (2003)

Lead Chloride (PbCl2) PbCl2-P2O5 Talib et al. (2003)

Lithium Chloride (LiCl) LiCl-P2O5 Loh et al. (2005)

Tellurite (Te) Boron (B) B2O3-TeO2 Halimah et al.(2005)

Sidek et al.(2006)

Zink (Zn) ZnO-TeO2 Rosmawati et al. (2008)

Sidek et al.(2009)

Ferrum (Fe) Fe2O3-TeO2 Zarifah et al. (2010)

PbO-P2O5

B2O3-TeO2

Ag2O-B2O3

Glass samples prepared by melt

quenching technique @ UPM

Glass Former Network Modifier Glass Samples Researchers

Ternary Oxide Glass Series

Borate (B) Bismuth (Bi) Lead (Pb) PbO-Bi2O3-B2O3 Sidek et al. (2005)

Hamezan et

al.(2006)

Phosphate (P) Lithium (Li) Lithium Chloride

(LiCl)

LiCl-Li2O-P2O5 Low et al. (1999)

Sidek et al.(2003)

Magnesium (Mg) Lead Chloride

(PbCl2)

PbCl2-MgO-P2O5 Sidek et al.(2004)

Zink (Zn) Lithium (Pb) Li2O-ZnO-P2O5 Sidek et al.(2005)

Zink (Zn) Lead (Pb) PbO-ZnO-P2O5 Sidek et al.(2005)

Bismuth (Bi) Lead (Pb) PbO-Bi2O3-P2O5 Sidek et al.(2006)

Calsium (Ca) Copper (Cu) Cu2O-CaO-P2O5 Talib et al. (2008)

Tellurite (Te) Boron (B) Silver (Ag) Ag2O-B2O3-TeO2 Halimah et al.

(2005)

Zink (Zn) Aluminum Floride

(AlF)

AlF-ZnO-TeO2 Sidek et al.(2009)

Boron (B) Lead (Pb) PbO- B2O3-TeO2 Iskandar et al.

(2010)

Zink (Zn) Neodymium (Nb) Nb2O5- ZnO- TeO2 Mohamed et al.

(2010)

Boron (B) Zink (Zn) ZnO- B2O3-TeO2 Ayuni et al (2011)

Selected some of the prepared ternary glass samples at the Department of Physics, Universiti Putra

Malaysia.

GeO2-PbO-Bi2O3

AgI-B2O3-TeO2

PbO-B2O3

SEM Photos XRD Pattern of Starting Materials

TeO2 powder

TeO2 glass

ZnO Powder

TeO2-ZnO glass

0200400600800

1000120014001600180020002200240026002800300032003400

10 20 30 40 502 theta

Inte

nsi

ty (

a.u)

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

10 20 30 40 502 Theta

Inte

nsi

ty (

a.u)

0

5000

10000

15000

20000

25000

30000

35000

10 20 30 40 50

2 Theta

Inte

nsi

ty (

a.u)

TeO2-ZnO-AlF3

glass

AlF3 (97.0%) Powder 16

XRD patterns

100

600

1100

1600

2100

10 20 30 40 502 theta

Inte

ns

ity

(a

.u)

TZ7

TZ6

TZ5

TZ4

TZ3

TZ2

TZ1

TZ0

• no discrete or continuous sharp peaks

• but broad halo at around 2 260 - 300, which reflects the characteristic of

amorphous materials.

• absence of long range atomic arrangement and the periodicity of the 3D network

in the quenched material

400

600

800

1000

1200

1400

1600

1800

10 20 30 40 50

2 thetaIn

ten

sity

(a.u

)

S5

S4

S3

S2

S1

TeO2)1-x (ZnO)x (x = 0.1 to 0.4 in 0.05) (TeO2)90(AlF3)10-x(ZnO)x (x = 1 to 9)

binary ternary

17

Ultrasonic System

Schematic representation of (a) simple pulse ultrasonic system. (b) Envelope of pulse echo train and (c) detail of each echo as seen on oscilloscope display

18

Ultrasonic Pulse Echo Overlap System

Pulse echo overlap system Pulse echo overlap waveforms

Block diagram of the experimental

set up – ultrasonic wave velocity

and attenuation measurement

(Mepco Engineering College,

INDIA)

19

Ultrasonic System

Ultrasonic – MBS

8000 Ultrasonic Data

Acq. System

20

21

Important Physical Properties

Density is defined as the mass per unit volume.

– Density is an intensive property of matter, meaning it remains the same regardless of sample size.

– It is considered a characteristic property of a substance and can be used for material’s classification

Density Measurement (Archimedes Method)

acaca

as ww

w

Molar volumes

MV

Physical Properties

Variation of density and molar volume with mol% Bi2 O3

in Bi2 O3–B2 O3 glass systems.

The increase of the density of the glasses

accompanying the addition of Bi2 O3 is probably

attributable to a change in cross-link density and

coordination numbers of Bi3+ ions.

26

26.5

27

27.5

28

28.5

29

0.55 0.6 0.65 0.7 0.75 0.8 0.85

Mole fraction of TeO2

Mo

lar

vo

lum

e(c

m3 m

ol-1

)

4650

4700

4750

4800

4850

4900

4950

5000

Den

sit

y (

kg

m-3

)

Density and molar volume of TeO2.B2O3 glasses

28

28.5

29

29.5

30

30.5

0.05 0.10 0.15 0.20 0.25 0.30 0.35

Pecahan Mol Ag2O

Isip

ad

u m

ola

r (c

m3)

4800

4900

5000

5100

5200

5300

Ketu

mp

ata

n (

kg

/m3)

Density and molar volume of [(TeO2)x (B2O3)1-x)]1-y [Ag2O]y

22

Density and Molar Volume

3500

4500

5500

6500

7500

0 20 40 60 80

Bismuth Oxide (mol%)

Den

sit

y (

kg

m-3

)

Dependence of density on the composition of bismuth oxide

glass systems as measured by El-Adawy and Moustafa (1999)

(5 - 45 mol%), Wright et al (1977) (20 – 42.5 mol%) and

present works (40 – 70 mol%).

23

Density & Molar Volume

4700

4800

4900

5000

5100

5200

5300

5400

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Mole fraction of ZnO

De

ns

ity

(k

g/m

3)

22

24

26

28

30

32

34

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Mole fraction of ZnO

Mo

lar v

olu

me

(1

0-6

m3m

ol-1

)

•Similar behaviour as El-

Mallawany (1993).

•Addition of ZnO causes some

type of structural

rearrangement of the atoms (Hoppe et al. (2004).

•Possibility for the alteration of

the geometrical configuration

upon substitution of ZnO into

the tellurite glassy network.

24

Density & Molar Volume

4700

4800

4900

5000

5100

5200

5300

5400

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Mole fraction of ZnO

De

ns

ity

(k

g/m

3)

22

24

26

28

30

32

34

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Mole fraction of ZnO

Mo

lar v

olu

me

(1

0-6

m3m

ol-1

)

•The increase in density indicates zinc ions enter

the glassy network

•The decreases in the molar volume was due to the

decrease in the bond length or inter-atomic spacing

between the atoms

• The stretching force constant (216 N/m – 217.5

N/m) of the bonds increase resulting in a more

compact and dense glass.

• Atomic Radius (Shelby, 2005).

•R(Zn2+)(0.074 nm) << R(Te2+)(0.097 nm)

•there is no anomalous structural change (non-linear

behaviour)

25

Elastic constants of the glasses

Longitudinal modulus

Shear modulus

Bulk modulus

Poisson’s ratio

Young’s modulus

Debye Temperature

2

lVL

2

sVG

22

3

4sl VVK

22

22

2

2

sl

sl

VV

VV

22

22243

sl

sls

VV

VVVE

mDt VM

Np

k

h 3

1

4

9

3

1

33

12

lS

mVV

V

26

27

[(TeO2)65(B2O3)35]1–y[Ag2O]y glasses

(Halimah et al. 2010)

Pure and WO3 dopedCeO2–PbO–B2O3 glasses

(Singh & Singh 2011)

Figure 17 Density and molar volume of selected glass samples.

Table 6 Measured density (ρ), molar volume (V), longitudinal ultrasonic velocity (vl), shear

ultrasonic velocity (vs), elastic moduli, Poisson's ratio (σ), and fractal dimension (d = 4G/K )

and (E/G) ratio of (TeO2)90(AlF3)10-x(ZnO)x glasses (Sidek et al. 2009).

Elastic modulus of zinc oxyfluorotellurite glasses

Ultrasonic Wave Velocity

Compositional dependence of the velocity of

longitudinal and shear acoustic waves in Bi2

O3–B2 O3 glass systems.

Both increase at first with increasing Bi2 O3

mol% up to a maximum at 25 mol% Bi2 O3

and then decrease as the Bi2 O3 mol%

increases further.

1000

1500

2000

2500

3000

3500

4000

0.05 0.10 0.15 0.20 0.25 0.30 0.35

Pecahan mol of Ag2O

Hala

ju u

ltraso

nik

(m

/s)

Compositional dependence of the velocity of longitudinal and

shear acoustic waves in [(TeO2)x (B2O3)1-x)]1-y [Ag2O]y glass

1500

2000

2500

3000

3500

4000

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Mole fraction of ZnO

Ve

loc

ity

(m

/s)

Longitudinal

Longitudinal

Shear

Shear

Compositional dependence of the velocity of longitudinal and shear acoustic waves in [(ZnO)(TeO2) glass

28

Ultrasonic Wave Velocity

Lead Magnesium Chloride

Phosphate Glass

29

Elastic Modulus

Dependence of longitudinal modulus on

the composition of Bi2 O3–B2 O3 glass

systems.

One reason for this difference may come from the

volume effect, in that C44 expresses the resistance

of the body to deformation where no change in

volume is involved, while C11 expresses the

resistance where compressions and expansions

are involved.

10

20

30

40

50

60

70

0.05 0.10 0.15 0.20 0.25 0.30 0.35

Pecahan mol Ag2O

Mo

du

lus k

en

yal (G

Pa)

L

E

K

G

Compositional dependence of the longitudinal and shear modulus of [(TeO2)x (B2O3)1-x)]1-y [Ag2O]y glass

30

Elastic Moduli

15

20

25

30

35

40

45

50

55

60

0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4

Mole fraction of ZnO

Elastic M

od

uli (G

Pa)

Longitudinal Modulus, L

Young’s Modulus, E

Bulk Modulus, K

Shear Modulus, G

31

Elastic Properties

Mole fraction, x 0.3 0.4 0.45 0.5 0.6

Elastic stiffness (GPa)

C11

C44

C12

48.9

18.0

12.9

48.8

18.0

12.7

47.5

17.4

12.7

47.3

17.5

12.3

47.3

17.2

13.0

Young's modulus, E

(GPa)

43.5 43.5 42.2 42.2 41.8

Bulk modulus, B (GPa) 24.9 24.7 24.3 24.0 24.4

Poisson's ratio, 0.208 0.207 0.211 0.207 0.215

Fractal dimension 2.90 2.92 2.87 2.92 2.82

Molar volume, V

(cm3/mole)

34.2 33.8 34.2 33.9 33.3

Number of atoms per

volume (x1028

atoms/m3)

9.67 8.90 8.37 8.00 7.24

Debye Temperature (K) 291 275 263 255 238

The room temperature elastic properties

of (PbO)x(P2O5)1-x glasses

Mole fraction, y 0.04 0.06 0.07 0.1

Elastic stiffness (GPa)

longitudinal, c11

shear, c44

c12

50.4

17.1

16.3

44.3

16.0

12.3

43.0

15.9

11.2

35.7

14.8

6.03

Young's modulus, E

(GPa)

42.4 39.0 38.4 33.9

Bulk modulus, B (GPa) 27.6 23.0 21.8 15.9

Poisson's ratio, 0.244 0.217 0.206 0.145

Fractal dimension 2.47 2.79 2.92 3.73

Molar volume, V

(cm3/mole)

33.5 33.5 33.3 33.4

Number of atoms per

volume (x1028

atoms/m3)

9.60 9.65 9.72 9.78

Debye Temperature (K) 276 266 264 251

Room temperature elastic properties of

(PbCl2)y(PbO.2P2O5)1-y glasses

32

Elastic Properties

33

34

Elastic properties of ZnO-TeO2 glasses (Sidek et al. 2010)

1500

2000

2500

3000

3500

4000

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Mole fraction of ZnO

Ve

loc

ity

(m

/s)

15

20

25

30

35

40

45

50

55

60

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Mole fraction of ZnO

Elastic M

od

uli (G

Pa)

0.19

0.2

0.21

0.22

0.23

0.24

0.25

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Mole fraction of ZnO

Po

isso

n's

Rati

o

3.1

3.3

3.5

3.7

3.9

4.1

4.3

4.5

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

Mole fraction of ZnO

Mic

ro

hard

ness (

GP

a)

Shear

Longitudinal L

E

K

G

Ultrasonic velocities Elastic moduli

Poisson’s ratio Micro-hardness

35

Elastic moduli of selected binary glassy materials.

Elastic Moduli (GPa)

Material Density L G K E References

15Sm2O3-85P2O5 3.280 66.42 23.63 34.91 57.84 0.224 Sidek et al. (1988)

15La2O3-85P2O5 3.413 67.63 23.05 36.90 57.23 0.241 Sidek et al. (1988)

15Nd2O3-85P2O5 3.233 70.50 24.80 37.40 60.90 0.229 Senin et al. (1993)

15Bi2O3-85P2O5 4.418 56.8 19.2 31.2 47.9 0.244 Sidek et al. (2011)

20Ho2O3-80P2O5 3.327 73.1 24.7 40.1 Senin et al. (1996)

20Nd2O3-80P2O5 3.358 67.4 24.1 35.3 58.8 0.22 Sidek et al. (1993)

20Sm2O3-80P2O5 3.326 63.1 23.4 31.9 56.5 0.20 Sidek et al. (1993)

20Ce2O3-80P2O5 3.254 74.4 25.0 41.1 62.3 0.23 Sidek et al. (1993)

14Ag2O-86B2O3 2.850 44.15 13.37 26.32 Saunders et al. (1987)

20PbO-80B2O3 3.801 45.4 14.70 25.90 43.0 0.262 Azman et al. (2002)

40PbO-B2O3 4.852 76.09 25.15 42.54 63.04 0.253 Sidek et al. (2003)

40Bi2O3-B2O3 5.262 74.67 27.70 37.75 66.75 0.205 Sidek et al. (2003)

30PbO-70B2O3 4.019 71.40 22.80 41.00 57.60 0.265 Azman et al. (2002)

30PbO-70P2O5 4.135 47.30 15.70 24.00 39.20 0.252 Azman et al. (2002)

26Tb2O3-74P2O5 3.578 76.2 25.4 42.00 64.0 0.246 Senin et al. (1994)

26Ce2O3-74P2O5 3.234 72.5 24.00 40.60 60.00 0.233 Saunders et al. (2001)

26Pr2O3-74P2O5 3.338 74.3 24.3 41.9 61.1 0.257 Senin et al. (2000)

33Ag2O-67B2O3 4.030 72.18 19.17 46.61 Saunders et al. (1987)

30ZnO-70TeO2 5.211 56.06 19.39 30.21 47.92 0.236 Rosmawati et al. (2008)

36

Elastic moduli of selected binary glassy materials (cont)

33ZnCl2-67TeO2 4.63 50.8 15.10 30.6 39.0 0.289 El-Mallawany et al.

(1998)

30V2O5-70TeO2 4.564 44.1 11.5 28.8 30.5 0.289 El-Mallawany et al.

(1998)

30B2O3-70TeO2 4.89 63.62 23.33 32.51 56.48 0.21 Halimah et al. (2007)

30B2O3-70TeO2 4.78 0.21 Sidek et al.(2006)

TeO2 (pure glass) 5.101 56.40 19.90 Sidek et al. (1989)

TeO2 (pure glass) 5.105 59.1 20.6 31.7 50.7 0.233 El-Mallawany et al.

(1998)

TeO2 (pure crystal) 6.02 56.0 27.2 Arlt & Schweppe (1968)

P2O5 (pure glass) 2.52 12.1 Bridge et al. (1984)

SiO2 (pure glass) 2.203 30.7 Borgadus et al. (1965)

So far silicate based glasses are

practically well employed by

engineers for optoelectronic

devices development and

application.

However silicate glass has some disadvantages. As an alternative, more researchers are now preferred tellurite based glass to be used as a host matrix in laser applications. We also found that tellurite is the best glass host due to low melting temperature and in absence of hygroscopic properties as compared to borate and phosphate based glasses.

Potential Application of Glassy Materials

CD memory device

Optical switching device

Non-linear optical

devices

Electrochemical devices

Laser host

Infra-Red Fiber Optics

37

38

Next-generation large-scale panels

Glass substrates for LCDs

Next-generation large-scale panels by

contributing to form various functional films on

glass substrates. 39

…you could see what was in the fridge without opening it?

…you could have a

fish tank which is self

cleaning?

Self cleaning glass

40

When water hits a hydrophilic surface, it flattens and spreads out to form a thin sheet.

Hydrophilic

surface

=wetting

Water spreads

HYDROPHOBIC (WATER HATING)

When water hits a hydrophobic

surface, it beads.

Hydrophobic

surface

= beading

Water

beads

HYDROPHILIC (WATER LOVING)

Poor wetting

(beading)

Contact

angle > 90°

Good wetting Contact angle < 90°

When water hits a hydrophilic surface, it flattens and spreads out to form a thin sheet.

Hydrophilic surface

=wetting

Water spreads

HYDROPHOBIC (WATER HATING)

When water hits a hydrophobic

surface, it beads.

Hydrophobic

surface

= beading

Water

beads

HYDROPHILIC (WATER LOVING)

Poor wetting

(beading)

Contact

angle > 90°

Good wetting Contact angle < 90°

41

SELF CLEANING GLASS

THE LOTUS LEAF EFFECT The leaves of Lotus plants have the unique ability to avoid getting dirty. They are coated with wax crystals around 1 nanometre in diameter and have a special rough surface. Droplets falling onto the leaves form beads and roll off taking dirt with them, meaning the leaves are self-cleaning. Sometimes referred to as “The Lotus Leaf effect”

Scientists have mimicked nature at the nanoscale to create glass surfaces that are ‘self-cleaning’ like the Lotus leaf.

No more scrubbing of shower

screens!

Self cleaning glass Normal glass

No more Spiderman

window cleaner!

42

SELF CLEANING GLASS

HOW DOES IT WORK?

Glass is coated with a layer of nanocrystalline titanium dioxide (TiO2).

The titanium dioxide reacts to the ultraviolet (UV) component of sunlight causing a gradual break down and loosening of dirt.

This is known as the ‘photocatalytic’ stage

The reaction also causes the glass surface to become super hydrophilic. This forces water to spread across the surface like a sheet, rather than beading, thereby washing away the loosened debris on the surface of The glass as it falls. This is the ‘hydrophilic’ stage.

APPLYING A MONOLAYER TO GLASS

GLASS NANO COATINGS

OptiView Anti-reflective glass made by

Australian company Pilkington.

Switchable glass changes from transparent to opaque.

A nano-layer of a rod-like particle suspension is placed between two layers of glass.

Under normal conditions, the suspended particles are arranged in random orientations and tend to absorb light, so that the glass panel looks frosted or opaque.

But when a voltage is applied, the suspended particles align and let light pass, turning the glass clear.

SWITCHABLE GLASS

CONCLUSION

Glass is one of the most versatile and most

fascinating materials

Their uniqueness in physical, optical, thermal,

mechanical and chemical properties offer an

almost unlimited range of applications.

Ultrasonic system has been employed to

characterize their elastic properties.

Extensive series of investigation using borate,

phosphate and tellurite based glasses have

been carried out to study the effect of certain

oxides into those glass formers in terms of

physical properties such as density, molar

volumes and elasticity.