Vibrational study of mixed SiO2-GeO2 glasses

107

JournalofMolecularStructure,219 (1990)107-110 ElsevierSciencePublishersB.V.,Amsterdam-Printadin The Netherlands

VIBRATIONAL

K.E.LIPINSKA-KALITA*

STUDY

OF MIXED

GLASSES

SiO2-Ge02

and D.J.MOWBRAY

Clarendon Laboratory, Department of Physics, Parks Road, Oxford OX1 3PU. (England)

University

of Oxford,

SUMMARY the Fourier transform presents the results of This paper glasses in the infrared (FTIR) and Raman spectroscopic study of the system : SiOs(GeOs)-AlsOs-FesOs-KsO. The prominent features in FTIR due

region spectra are intense, broad bands in the 800-1200 cm-' and GeOI stretching motions of Si04 to antisymmetric

The wavenumbers of these bands varies with tetrahedra. to of the glass (SiOs/GeOs ratio) and they correspond

composition very weak

Raman bands. Dominant Raman bands were found in the 400-600 cm-' mixed vibration. We region and are mainly due to a stretch-bend for note that intensity of these bands appear to remain constant ratio. We that the glasses with different SiOa/GeOz suggest changes

observed

in the vibrational

spectra

of

glasses

SiOz-GeOs

may reflect the effect of structural substitution of Ge '+ for Si4+ and detailed investigation in the glass network. A more precise will be needed to provide a better understanding of the spectra of the analysed glasses. INTRODUCTION The purpose

of the present

interpret

FTIR

SiOs-GeOz

glasses

We expect tetrahedra to

absorption

that

a knowledge

understand

multicomponent

is

structurally

to

spectra

of

a

series

of

: Si0s(Ge02)-AlsOs-FesOs-KsO.

of the distribution

of SiOs-GeOs the

tetrahedral

Raman

and

in the system

in the network

better

investigation

glasses

distribution

network

of Si04 and

(ref.1) of

could

Ge04 help

tetrahedra

in

structures.

METHODS Glasses

of the same basic

0.5 FesOs, 6.5 KsO mol% 75 SiOs. 25 GeOs, prepared

SOSiO;50

with high

KZCOs powders.

composition:

but different

purity

GeOs,

25 SiOs.75

SiOs,

The components

0022-2860/90/$03.50

GeOe.

were weighed

On leave from Regional Laboratory Structural Research, Jagiellonian Karasia 3 (Poland)

80 SiOs(GeOs),

SiOs/GeOs

ratio

GeOs, Al(OH)s, out and

100

Al 0 , SIO:.

GeOs)

were

Fe(Cz04)*

2Hs0,

ground.

Mixes

of Physicochemical University, 30-060

O1990ElsevierSciencePublishersB.V.

13 (100

Analyses Krakow,

& ul

108 were

then

loaded

The melts

were

Fourier measured with

into alumina

quenched

transform

Raman small

infrared

in the 100-1300

a resolution

(without

at a sample

collected

at

collected

using

polarisation

Physics,

to

the

a Spex,

were

Model 250

1400

Digital

FTS

were

obtained with

laser.

Scattered beam.

from

the

514.5

The

laser

radiation

Spectral

Double data

were

system,

disks.

excited

171, Ar+

mW.

incident

Model

gratings.

data)

Samples

spectra

a Digilab

was

data

were

Spectrometer,equipped

acquisition

was

controlled

a microcomputer.

RESULT

AND DISCUSSION

The FTIR

absorption

-AlzOs-FezOs-KzO same basic contain

spectra

are shown

composition

unpolarised

The FTIR

and Raman

but

changes

compositional

with

The

in

spectra

(Fig.1)

SiOz/GeOz

glasses

frequencies

and

changes

(SiOz/GeOz

shift

with

bands

frequency

increasing

glasses

SiOz(GeOz) have

the

ratios.

Fig.2

of the same glasses.

of analysed

intermediate-frequency

continuously

in the system:

All these

different

spectra

spectra

systematic

of glasses

in Fig.1.

Raman

bands

note

at 1200-13OOOC.

absorption

using

, on the KBr pelletized

was usually

90'

with holographic with

-1

of the glass.

nm line from a Spectra power

and melted

(FTIR)

cm-' region

of 2 cm

spectra

fragments

crucibles

in air.

are

marked

intensities

and

spectral

ratio).

(400-600

cm-') of the

decrease

GeOz amount

of

by

infrared

in

in the glass

intensity

network.

We

that the frequency and intensity of the dominant Raman bands -1 region (Fig.2) appear to remain cm constant for

in the 400-600 glasses

with

different

rise to a new, weak

SiOz/GeOz

band

In the high-frequency spectra at

both

about

intensity ratio).

expected

these

Systematic

intensity variations This

frequencies changes

changes

are also

of the high-frequency of the SiOz/GeOz

to the degree modes

of GeOz

cm-') of the FTIR

stretching and

with

only

modes the

composition

observed

(1000-1200

glass appear

relative (SiOJGeOz

in the frequency

cm“)

Raman

bands

and with

ratio. in the case of the SiOz-GeOz

of localization

(ref.2,3).

gives

on the = 450 cm-' bands.

(1000-1200

bands

sort of behaviour

be related frequency

as a shoulder region

The addition

Si04 and Ge04 antisymmetric

their of

ratio.

of high

and

glasses

may

intermediate

109 sioa

(GeO,)

Glasses

-Al,O,-FeO/fe,O,-K,O 1060

-75GeO

I

100

I I

I

I 200

300

GeOl

I

J

800

400

1

1200

WaveNumbers/cm-’

Fig.1.

FTIR

absorption

spectra

of glasses

with

different

SiOZ/Ge02

ratio

CONCLUSIONS The changes along

the join

substitution angles

observed Si02-Ge02

nature main

and T-O bond

about

reflect

strenghts

and

be needed

the

symmetry

modes

of bulk

of the

effect

changes

of

glasses

structural

of

in the T-O-T

scattering

Raman

to provide

a better

producing

is that polarised

on blocks

spectra

bond

(where T = Si4+, Ge").

detailed

of the vibrational

advantage

(measured

may

and Raman

of Ge '+ for Si4+, producing

A more precise (ref.4) will

in the FTIR

glass)

vibrational

and

investigations

understanding

features.

spectral

depolarised

provide modes.

Raman

additional They

of

give

the The

spectra

informations also

very

110

S10,

(GeO,)

GlaSSE!S

-Al,O,-FeO/Fe,O,-K,O

Unpolarised

Frequency

Fig.2.

Unpolarised Si02/GeOz

Raman ratio

accurate

spectral

line

shapes

detailed

analysis

than

are

One of us hospitality

spectra

of

which

are

FTIR

(K.E.Lipinska-Kalita) and for permission

absorption would to use

Shlf

t/cm“

glasses

thus

different

with

amenable

to

much

more

spectra.

for thank W.Hayes like to the Raman scattering system.

REFERENCES 1

2

3 4

S.K.Sharma, D.W.Matson, structure of of the

J.A.Philpotts and T.L.Roush,Raman study SiOz-GeOz join glasses the along

J.Non-Cryst.Solids, 68 (1984) 99-114 P.Dean and D.C.Hibbens-Butler, R.J.Bell, germania silica modes in vitreous J.Phys. C3 (1970) 2111-2118 M.F.Thorpe and F.L.Galeener, Network (1980) 3078-3092 D.J.Mowbray and K.E.Lipinska-Kalita,

and

Localization beryllium

Phys.Rev.

dynamics, B.Hayes

-

of normal fluoride.

in

preparation

B22