FTIR SPECTROSCOPIC STUDY OF (l-~-y)(B~0~) …shodhganga.inflibnet.ac.in/bitstream/10603/378/10/10...be assigned to B-0 stretching vibration while the weak band at 656 cm-' is attributed

CHAPTER 3

FTIR SPECTROSCOPIC STUDY OF ( l -~-y)(B~0~)-x(Li~O)-y(MC1~) GLASSES

3. FT 1R Spectroscopic study of (1-x-y)(B203)-x(Li20)-y(MC12) (M= Cd, Zn) glasses

3.1. Introduction

The structures of alkali metal borate glasses have been the subject of

numerous investigations. Spectroscopic techniques including NMR'.~, am an"', and infrared'." ha\ e bccn mainly employed advantageously to probe the structure

of borate glasses. 'Vibrational spectroscopy is one of the most powerful techniques

for studying the structure of glasses. It is particularly useful for probing motion of

non-bridging atoms/ions or weakly coupled bridging atoms. Many investigators

have extensively made use of infrared spectroscopy in the past few years to

explain the strucl.ure of borate The important results of the 1R

spectroscopic studies of borate glasses reported in the literature and which are

used for the interpretation of the spectra of glasses in the present sludy are given in

the following paragraphs.

According to ~ r o ~ h - ~ o e ' ~ , the structure of boron-oxide glass consists of a

random net\vork ol' planar B03 triangles, with a certain fraction of six rne~nbered

boroxol rings. . Llut accordingto Mozzi and warren16, boroxol rings build up the

major part of' thc glass. Guha and ~ a l r a f e n " postulated that the structure of

vitreous UZo3 is made up of an equal proportion of boroxol rings and B 0 3

triangles. Pure boron oxide glass is characterised by a strong and rather narrow

Raman peak at 806 c m ' and by infrared reflection maxima at 656, 1276, and 1492

cm-I. Kristiansell and ~ r o ~ h - ~ o e " have assigned the strongly polarised Raman

peak at 806 c ~ n - ' to the triagonal deformation of the boroxol ring. On the other

hand the strong infrared band around 1276 cm" and the shoulder at 1492 c ~ n - ' can

be assigned to B-0 stretching vibration while the weak band at 656 cm-' is

attributed to the bending motion of the B-0-B centers within the network.

Pure U 2 0 3 contains only three co-ordinated boron atoms, but if alkali oxide

is added, some of these units transform into four co-ordinated tetrahedra. Bridging

oxygen atoms link adjacent BO, and B 0 4 groups thus building the a~norphous

network'! I n the literature' Raman and infrared spectroscopy were employed to

probe the continuous evolution of borate glass structures as a function of the

nature and concentration of alkali oxide modifier. The smallest alkali cations ~ i '

and Na' seem to i'avor complete disruption of the borate network into isolated

units, because ol'their high charge density. Correspondingly, the fraction of four-

co-ordinated boron atom after going through a maximum at x = 0.35 (mole % of

Na20 or Li20) is progressively and smoothly reduced towards a limiting value of

Lero as the glass composition approaches the ortho-borate stochiometry (x = 0.75).

On the contrary, the large and polariszable alkali ions (Rb',Cs') do not favor this

1.eversa1 of boron-oxygen co-ordination from four to three. ~ r i s c o m " pointed out

that the structure of'glasses with composition (B203)1.x-(R20)x (I1 = Li, Na, K, Rb,

Cs) consists of a B - 0 network, built up from planar three co-ordinate and

tetrahedral four co-orclinated boron atoms.

20 . The addition ol'l.i20 to B20, is reported to produce s~gnificant changes in

the Raman spectr,l. In particular the disappearance of the 806 cm" peak was

accompanied by a rap~tl increase in the intensity of a new strong polarised peak at

780 cm-I. But in the I I i spectra of B203-xLi20 glasses, the three peaks at 656,

1276, and 1492 c~n-I were found to be replaced by peaks at 676, 920, and 1376

cm-' respectikely. as the value of x was increased. In particular, the strong B203

band at 1276 c n - ' nearly disappeared at x = 0.33. The comparisons of the infrared

reflection spectra of B203-xLi20 and B203-xLi20-yLiCI2 glasses of various

compositions showed that the addition' of LiCI2 produced no new features in the

spectra of B ~ o ; - x I . ~ ~ o ~ ~ .

Kanlitsos ct al"'." have reported Raman and mid-IR study of sLi20-(I-

s)B203 (0.20s x 50.65) glasses containing high concentration of LizO. The

reflectance data wcre analysed by Kramers-Kronig inversion to obtain the optical

and dielectric properties of these materials. The study of the deco~ivoluted mid-

inrrared spectra has revealed a glass network built up of various boron-oxygen

groups, with structure and concentration strongly dependent on the Li20 content.

lnfrared reflectance spectroscopy applied to lithium borate glasses has led to a

number of interesting results regarding the borate network structure and the

lithium network interaction was suggested by ~ a m i t s o s ~ ' . I>econvolution of the

~nid-infrared part 01' thc spectrum has revealed the continuous evolution of the

network structure by the progressive creation and destruction of a variety of borate

units. The structure of fused B2O3 and of a series of sodium borate glasses are

reported by Andersn et all3. It is shown that hydrogen bond play an important part

in the atomic arrangement of the glasses of zero or low sodium content. Glasses

of high Na20 content in the system xNa20-1-xB203 (0.351 x 50.75) were prepared

and studied by Raman and far-infrared spectroscopy14. The far-infrared spectra of

alkali oxide glasses were used to probe the localised vibrations of the alkali cation

at their network sites.

A series of rubidium borate consisting of varying proportions of rubidium

oxide and boron osidc were studied by infrared spectroscopy in the 2 .5 -15 .5~ 22 - range by Quan and Adains . The experimental results of this study indicate that

\.itrcous rubidium borate glass is comprised of a mixture of B03 groups, BO',B04',

and boroxol groups, which form as a consequence of the introduction of Rb20.

Icxcept for BOj, the concentration of all the species increase uniformly up to 28

mole percentage of Rb20. Between 28 and 33-mole percentage, the increase is

accelerated. Beyorid this and up to 50-mole percentage, tetrahedraly co-ordinated

ilcvitrification yields crystalline rubidium metaborate. Structural and dynamieal

properties of lithium, cesium, and mixed alkali borate glasses have been studied by

the molecular dynamics It is reported in this literature that si~nulated

infrared absorption spectra reproduce the experimental spectra quite well.

The cationic: and anionic site dependence of the cation motion fiequency

was modeled through a Born-Mayer type potential in the ~ i t e r a tu re~~ . It was

shown that for nel.work sites of tetrahedral, octahedral, or cubic symmetry the

coulombic part of the potential did not contribute to the force constant of the

infrared active cation vibration. The effect of the cation on the borate glass

structure was thcn evaluated through the anionic site charge density, which is a

function of thc boron-oxygen groups present in the glass. The anionic site charge

density decreases upon increasing alkali-metal size, which indicated that the

structure depends mainly on the metal oxide content and not on the specific cation.

The vibrational Srecpencies of alkali-metal cations in their equilibrium positions in

borate, phosphate, germanate, silicate, and vanadate alkali oxide glasses have been

observcd as cation mass dependent bands in the far-IR spectra of this vitreous ' 5 systems-. .

The infrared absorption spectra of some selected ternary glasses of the

system Li20-B20;-A1203 have been reported. The effects of changing glass

composition on glass structure have been investigated by Khalifa et Infrared

hpectroscopy has i~ecn successfully used to study the network structure of the

systenl BaBzO,,-I<I.z, ZnB204-RF2, where R = Mg, Ca, Sr, or ~ a ~ ' . The slructure

of the starting glasses consists of borate groups in which the boron atoms are of

three and four-fold coordinations. Incorporation of fluorides has been found to

change the ratio of thrce and four-fold co-ordinated boron atoms by increasing the

three-fold co-ordination. It is assumed that the magnesium cation, having a higher

licld power than thc barium cations, favour the formation of magnesiu~n

containing groups of the F-fluoborite type in the glass consisting of (UO3)-

trigonals and (Mg03F3)-octahedra.

'I'he structure of the ternary glass system xMg0-yNa20-B203 has been

i~nalysed by Karnithos et a128 in order to elucidate the role of MgO in such glasses.

I t is shown that for colnpositions x + y = 0.33, 0.53, and 0.67 the presence of M ~ ~ '

cations causes mainly the destruction of diborate groups in favour of boroxol

rings, tetrahedra groups, pyroborate, and meta-borate units. The same borate

moieties are also formed for glass composition with x + y = 1.0, but they mainly

originate li-om the destruction of ortho-borate units and di-borate groups.

Doweidar ct alx studied the structure of Zn0-Pb0-B203 glasses by using the

infrared spectroscopy. In this glass system, ZnO is found to enter the structure

both as a glass ~notlificr and as a glass former. In these glasses a zinc lead borate

network is proposed to be responsible for the change in both the conductivity and

the density. Both rhc two quantities increase with the increase of the OIB ratio.

'I'he effect of the cations M ~ " , cd2+, zn2+, ca2+, sr2+, ~ a " , AI~ ' , ~ i ~ ' , or zr4' on

the frequencies ant1 intensities of the characteristic infrared absorption bands of

some selected high lead silicate glasses have been investigated recently in the

range of 200 - 4000 cm-' using infrared ~ ~ e c t r o ~ h o t o m e t e r ~ ~ . The 1R spectra of

AgX-Ag20-H203 ( X = 1. Br) glasses have been reported3' to be characterised by

two groups of'absorption bands centered around 1255 -1310 and 945 -1010 cm-I.

The former band has been reported to be originating from the v3 lnodc in B 0 3

groups and the latter to the v3 mode in B 0 4 groups. This glass contained B03 and

DO4 groups, wherc non-bridging oxygens are present in B 0 3 groups only. ~ g '

Ions were bound to the non-bridging oxygens with strong partial covalency.

Reports on the study of the structure of more complex glasses are available

in the literature. Tlne structure of lithium borosilicate glasses containing vanadium

and iron were studied by using both infrared and x-ray diffraction techniques32.

The iron acts as a iretwork modifier at low iron contents. In glasses containing no

vanadium, the band at 1620 cm-I indicate the formation of Si04 units within the

network structure. The shift of band at 1360 cm" to 1350 cm" indicates decreases

in the number of B 0 4 units and the formation of B 0 3 groups. When the

composition of VzOS is 2.5 mole percentage, and when the samples were heated

Ibr ten minutes, it was reported that the band at 1415 cm-I of the untreated sample

shifted to 1400, 1410, and 1420 cm-' with increasing heat treatment time

indicating that the heat treatment breaks the B-0 bonds from DO3 groups and

produces the non-bridging oxygens.

Estensivc study of the glass system B203-xLi20-yLiC1 has established 20.38

that addition of 12i~CI to B203-Li20 glass, does not induce drastic changes in the

structure. Glasscs containing LiCl and low concentration of Li20 consists mainly

of BO; groups and the structure of the glass is relatively open. The large CI. ions

can be accommodated relatively easily in this structure. Because of the negative

charge, the CI- ions are located at large distances from B 0 4 groups with an excess

negative charge. If the concentration of LizO is increased, the number of B 0 4

groups increases arid the structure is not as open as the structure of pure B2O3. AS

a result it is more difficult to accommodate C1- ions in this structure. Therefore the

introduction ol'C1- ions will lead to an expansion of the glass structure. In order to

accommodate the lnrgc CI- ions, the glass structure tries to Corm open structures by

clustering of several L303 groups. This means that probably the B 0 4 groups also

bho\v a tendency towards clustering. In this way, two different structures are

formed; the open B 0 3 structure containing the large Cf ions and the dense

structure with majorit) of BO4 groups.

3.2. Work undertaken in the present study

In this chapter, the author presents Fourier transform infrared spectroscopic

study of the glass 5;ysterns (1-x-y)(B203)-x(Li20)-y(MCI2) (M=Cd, Zn). This work

was undertaken to study how the structure of B203-Li20 is modified by the

presence halides likc LnC12 and CdCI2 and to compare the structure of the new

system with that ol'other binary and ternary systems of borate glasses. The effects

of the variation ol' concentration of Li20, and CdClz or ZnC12 on the 1R bands

were investigated and the peaks corresponding to different types of borate groups

were identified.

3.3. Experimental details

( I - ~ - y ) ( I 3 ~ 0 ~ ) - x ( L i ~ O ) - y ( M C l ~ ) (M=Cd,Zn) glasses of different

co~npositions as shown in table 3.1 were prepared from appropriate amount of

analar grade boric acid (H3B03), lithium carbonate (Li2C03), and cadmium

chloride (CdCI2) or zinc chloride (ZnC12). Calculated quantities of the chemicals

were mixed thoroughly in an agate mortar and heated to 9 5 0 ' ~ in a crucible, so

that a homogeneously mixed melt was obtained. The samples were made using

splat-quenching te'chnique, which is described in section 2.3 of chapter 2. The

glasses were then ;annealed at a temperature of about 4 5 0 ' ~ for 4h. The familiar

KBr pellet technique was used for recording the IR spectrum of the samples. The

spectra Rere recorded at room temperature in the range 400-4000 c1n.l. The

innorphous nature of the glass samples was confirmed by the X-ray diffraction. X-

ray diffraction pattcrns of two typical glass sample are given in figure 3.a. The

presence of CdClz or ZnClz of varying concentrations in the glass samples was

confirmed by chemical analysis. i

Figure 3.a. X-ray diffraction pattern of (a) glass sample BCLl (b) glass sample BZL 1

3.4. Results and Discussion

The FTIR ~ranstnission spectra of the glass systems (1-x-y)(B,03)-x(Li20)-

y(MCl2) (M=Cd.%n) for different concentrations of the components recorded in

the present study are shown in figures 3.1-3.22. The various spectral features are

discussed based on thc composition of the glasses, in the following sections.

1 able 3.1. Glass co~nposition

Wavenumber (an-')

k'igure 3.1 FTIR spectrum of BCL 1 glass

- .- Serial Glass composiiion Code

No.

I 0.7SB201-0.20.ZnC12-0.05Li20 BZLl

2 0.70B,03-0.20.LnCI2- 0. IOLi,O BZL2

3 0.65B2O,-0.2OLnC1,- 0. 15Li20 BZL3

a 0.60B10,-0.?0.ZnCI,- 0.20Li20 BZL4

5 055R1O1-020ZnC1,- 0.25Li20 BZL8

6 0.75B,03-O05ZnCl2- 0.20Li20 BZL5

7 070B,O,-0.1 0ZnC12- 0.20Li20 BZL6

8 0.65B20i-0. I S%iiCI2- 0.20Li20 BZL7

9 0.80B103-0 IOZnC1,-O.IOLi,O BZL9

10 0.60BI0,-0. IOZnC12- 0.30Liz0 BZLlO

I I 0.50B203-0. IOZtiC12- 0.40Li20 BZLl l

Serial Glass composition Code

No.

1 0.75B201-0.20CdC12-0.05Li20 BCLl

2 0.70B201-0.20CdC12-0. IOLi,O BCL2

3 0.65B203-0.20CdCI2-0. 1 5Li20 BCL3

4 0.60B203-0.20CdC12-0.20Li20 BCL4

5 0.55B201-0.20CdC12- 0.1 5Li20 BC1.8

6 0.75B203-0.05CdC12-0.20Li20 BCLS

7 0.70B20,-0.10CdC12-0.20Li20 BCL6

8 0.65B201-0.15CdC12-0.20LiD BCL7

9 0.80B203-0. IOCdCI,-0. IOLi,O BCL9

10 0.60B203-0. 10CdC12-0.30Li20 BCLlO

11 0.50B201-0.10CdC12-0.40Li,0 BCLl l

Wavenumber (cm-')

1,'igure 3.2 FTIR spectrum of BCL2 glass

Wavenumber (cm-')

Figure 3.3 FTIR spectrum of BCL3 glass

Wavenumber (cm")

Figure 3.4 FTIR specirum of BCL4 glass

Wavenumber (cm'l)

I:ig~~re 3.5 FTIR spectrum of BCLS glass

- 1 ~ 7 I I I I I I I I I t rn EC am ZBO m m m m am IM isao ~ a a lam 750 &

Wavenumber (cm-')

1:igure 3.6 FTIR spectrum of BCL6 glass

Wavenumber (cm-')

I;igure 3.7 FTIR spectrum of BCL7 glass

Wavenumber (cm.')

Figure 3.8 FTIR spectrum of BCL8 glass

Wavenumber (cm-l)

Figure 3.9 FTIR spectrum of BCL9 glass

Wavenumber (cm-I)

IFigure 3.10 FTIR spectrum of BCL 10 glass

Wavenumber (cm-')

k'igure 3.1 1 FTIR spectrum of BCL 1 1 glass

Wavenumber (cm.')

Figure 3.12 FTIR spectru~n of BZL 1 glass

Wavenumber (cm-I)

Figure 3.13 FTIR spectrum of BZL2 glass

Wavenumber (cm-l)

I:igure 3.14 FTIR spectrum of BZL3 glass

Wavenumber (cm-I)

Figure 3.15 FTIR spectrum of BZL4 glass

Wavenumber (cm-')

1:igure 3.16 FTIR spectrum of BZL8 glass

Wavenumber (cm-')

1;igure 3.17 FTIR spectrum of BZL5 glass

Wavenumber (cm-')

Figure 3.18 FTIR spectrum of BZL6 glass

Wavenumber (cm")

Figure 3.19 FTIR spectrum of BZL7 glass

Wavenumber (cm-I)

Figure 3.20 FTIR spectrum of BZL9 glass

Wavenumber (cm-')

Figure 3.2 1 FTIR spectrum of BZL 10 glass

Wavenumber (cm-I)

Figure 3.22 FTIR spectrum of BZLl 1 glass

3.4.1 (I-x-y)(B203)-x(Li20)-y(CdC12) glass system.

3.4.1.a Effect of variation in the concentration (y) of CdCI2 (0.05 5 y 5 0.20) when

the concentration (x) of Liz0 (x = 0.20) was kept constant.

The details of the glass samples containing different concentrations (y) of

CdCI2 but constant concentration (x) of Li20 used in the present study are given

below while the observed band positions are tabulated in table 3.2.

Sample code Mole % of LizO Mole % of CdC12 Mole % of B203

BCL5 0.20 0.05 0.75

BCL6 0.20 0.10 0.70

BCL7 0.20 0.15 0.65

BCL4 0.20 0.20 0.60

Table 3.2 Observed 1K bands of (l-~-y)(B~O~)-x(Li~O)-y(CdC1~) glass system for 0.05 I y <_ 0.20, x = 0.20

. -- -- .. Sample IR band position (cm-I)

c d e ~p

BCL5 416 428 450 496 688 783 915 1025 1078 1252 1360 1651 3429

A BCL6 417 428 468 496 692 783 1025 1369 3478

BCL7 417 428 155 509 697 783 . 926 1026 1104 1253 1361 1449 1653 3440

BCL4 416 425 455 509 694 1013 1382 3447

The F 1'IR spectra of the ternary glass sample BCLS containing the lowest

concentration oF 0.05 mole percentage of CdC12 is shown in figure 3.5. The

spectrum exhibits niany spectral features amongst which the 1110st prominent are

the intense absorption bands at 688, 1026, 1360 cm-I and weak shoulders at 783,

915, 1078: and 1252 em-'. Kamitsos et all' has reported that the low frequency

region of the mid-inciared (550-800 cm-I) spectrum of BIG),-Li20 glass is

dominated by bend~ng vibrations of various borate units. The strongest feature of

the mid-infrared spectrum of B203-Li20 glass with low Li20 content is a single

band at 700 cm-I ~ L I C to bending of B-0-I3 linkages of the 1 3 - 0 network. For

hrghcr conccl~tration 01. LiIO, two well-separated bands at 708 cm-I and 765 cm.'

are observed"'. The 765 cm.' band increase in intensity, relative to that at about

700 cm.', until they merge to form one band and then increase in intensity and

frequency with increase in concentration of Li20. The spectra of both 2Li20.B2O3

and 3 Li2O.BzO3 show bands in this region, at 755 cm-I and 775 c~n- ' respectively,

which may be assigned to '0-B-O' out of plane bending vibration of 8 2 0 ~ ~ -

(pyroborate) and ~ 0 3 ~ - (orthoborate) units. Thus, the 760 cm-I band of the glasses

indicate the presence of B ~ o ~ ~ - andlor B O ~ " units. A weak band at 650c1n-I is

probably due to the B-0-B in-plane bending vibration of B20j4- (pyroborate) and

~ 0 3 ~ - (orthoborate) units. The sharp peak at 688 cm-I in figure 3.5 which is close

to the 700 c~n-I bald in the low Li20 content B20;-Li20 spectrum" is assigncd to

hending of H-0-B linkages of the B - 0 network. The weak shoulder at 783 cm-I,

which is close to the strong band at 775 cm-' of B203-Li20 glass containing high

concentration of LizO is assigned to -0-B-O' out of plane bending vibration of

130;" (orthoborate) units.

I t is now witlely accepted3; that the broad band structure in the region 1 150-

1500 cm-' is due to LI-(1 band stretching of B0; units while that in the region 850-

1100 em" is attrihutcd to the B - 0 stretching of B04 units. In the absorption

region of B04: three bands are evident at 880,1056 and 900 - 1000 cm-'.

(:rystallinc tetraborate cotnpounds show strong bands at 1020 and 880 cm-I, while

the lithium diborati co~npound absorbs strongly at 970 cm-I. Thus both 1050 and

880 cm-' bands are assigned to B 0 4 vibration of tetrahedra (triborate, pentaborate)

groups. Kamitsos t:t all' has reported that the bands at 871, 965 and 1060 cm-I are

due to vibration of' borate arrangements containing B04- tetrahedra (pentaborate,

diborate and triborate) respectively. The analogous vibrations of B 0 4 tetrahedra

belonging to diborate groups give rise to an absorption in the 900-1000 cm-I

region. In the prescnt study (Fig. 3.5), the absorption peaks around 915, 1078 and

1026 cm" arc attributed to vibration of borate arrangements containing B04-

tetrahedra in triborate, diborate and pentaborate groups respectively.

In the case of zinc borate glasss containing PbO, the 1R absorption band at

1340 em-' is assigned to B - 0 stretching vibrations of triagonal ~0; '- units in

metaborates, pyroborates and orthoborates. In comparison with the 1340 cm-'

band in zincboratc glass. the broad and intense peak around 1360 cm-I (Fig. 3.5) in

tllc present study is assigned to B-0 stretching vibration oftriagonal 1 3 0 ~ " units in

n~etaborate, pyrobol-ate and orthoborates. The shoulder at 1252 c ~ n " in figure 3.5

is close to the 1250 cm-' band in the IR spectrum of xMg0-yNa20-B203 glasses28.

l'his band is assigned to a B - 0 stretching vibration of B-0-B linkages, involving

~nainly boroxol and tetraborate groups.

Tarte'.' has concluded that Li04 tetrahedra give bands in the 400-550 cm-I

region. It is reporled 11.35-37 that simultaneous occurrence of peaks around 239,

410 and 475 cm-' is a reliable proof of the presence of vibrations of ~ i ' cations

against their netwo1.k sites. It is also reported that8 the shoulder at 450 cm'l in the

spcctra of ZrtO-PbO-Bz03 glasses investigated can be attributed to vibrations of

metal cations such as 1'b2' or zn2+. In the present study (Fig. 3.5), the bands at

416, 428 and 496 cm-I are attributed to the vibrations of Li' cations against their

network and the comparatively stronger band at 450 cm'l is attributed to vibration

of the ~ d " metal cations.

The F-l'lli spectra of the glass samples (BCL6, BCL7 and BCL4)

containing higher concentration of CdC12 (y > 0.05 mole percentage) are shown in

figures 3.6, 3.7 and 3.4. All the spectra contain the absorption bands around 416,

428, 450, 496. 688. I025 and 1360 cm-' as in the case of BC13 glass containing

t l~c smallcst concc~itration of CdCI2. Hence the assignments of these bands are

identical to those mentioned in the preceding paragraph. It may be concluded that

the same structural units are present in the glasses containing different

concentrations ol' CdCl*. But it is observed that the increase in concentration of

CdClz (y > 0.05) causes the destruction of bands at 783, 9 15 and 1252 c1n.I.

The spectrum of the glass with y i 0.15 mole percentage give one sharp

band at 688 cm-' and a shoulder at 783 cm'l. The 688 cm-' band increases in

intensity with increase in CdCI2 concentration and the shoulder merges with this

band resulting in a :single 1R absorption peak at 694 cm-I for thc sample with y =

0.20 mole percenta.gc. At y = 0.05 mole percentage there is a main band at 1025 - I ctn and two weaker bands at 91 5 and 1078 cm-'. Increase of y causes these

bands to overlap to give a broad band around 1025 cm-' in the sample BCL6 and

around 1013 cm" in the sample BCL4. But this band shows three sharp peaks at

926, 1025 and 1104 cin-' in the spectrum of the sample BCL7. This band as in the

case of BCL5 is assigned to vibration of borate arrangements containing B04-

tetrahedra (diboratt. triborate and pentaborate).

In the case of lithiuin borate glass33 containing, Li2S04, the IR absorption

band at 1430 cm-' is assigned to B03 with non-bridging oxygens (NBOs). It is

evident that, for thi:i glass, NBOs are formed at the expense of BO, and B 0 4 units.

In the present study. the 1R absorption peak observed at 1449 cm-' for the glass

composition 0.65 13203-0.20Li20- 0.15CdC12, is close to 1430 cm-' band of the

spectrum of lithiun-I borate containing lithium sulphate. This band is attributed to

H 0 3 units with non-bridging oxygens. It is worth mentioning that the absorption

bands around 160iJ and 3429 cm-I in the spectra of (1-x-y)(B203)-x(Li20)-

y(CdCI2) glasses are due to the 0 - H stretching vibrations.

Irion and ~ o u z i " has reported that, the addition of LiCl to B203-Li20 glass,

does not produce ar,ly change in the Raman and IR spectra of binary lithiuin borate

glass. It may thus be concluded that the presence of chlorine docs not produce any

major moditication in the vitreous boron-oxygen network.

In comparison with the reported spectra of binary and ternary glasses20.", it

may be concluded that the structure of the (1-x-y)(B203)-x(Li20)-y(CdClz) glasses

with the composition x = 0.20, 0.05 I y 5 0.20 consists mainly of a continuos

random network cc~ntaining boroxol rings, B 0 i tetrahedra containing triboratc,

diboratc and pentaboratc groups and ~ 0 3 ' - containing orthoborate groups. .fhc

peak of appreciable intensity around 1449 cm-I (for y = 0.15 mole percentage)

strongly indicated that NBOs arc formed at the expense of B 0 3 and B 0 4 units.

3.4.1.b Effect of variation in the concentration (x) of Liz0 (0.05 S x 5 0.20)

when the concentration (y) of CdC12 (y = .20) was kept constant.

The details of the glass samples containing different concentration (x) of

LizO but constant concentration (y) of CdC12 used in the present study are given

below while the observed band positions are tabulated in table 3.3.

Sarnple codc Mole % of Li20 Mole % of CdCI2 Mole % of B2O3

UCI,1 0.05 0.20 0.75

0.10 0.20 0.70

HCL3 0.15 0.20 0.65

13CL4 0.20 0.20 0.60

l3CL8 ! 0.25 0.20 0.55

'l'able 3.3. Observcd 1R bands of (1-x-y)(B203)-x(Li20)-y(CdC12) glass system for 0.05 < x i 0.20, y = 0.20

Sample 1R band position (cm.')

codc

BCLl 416 425 455 509 696 783 925 1026 1103 1252 1361 1437 1651 3442

BCL2 419 431 455 509 696 783 925 I026 1103 1252 1361 1435 1651 3442

BCL3 413 431 458 509 690 783 1026 1361 1651 3442

BCL4 416 425 451 509 694 1013 1382 3447

BCLX 416 428 452 509 695 998 1378 3453 --

The F U R spectra of glasses containing 0.20 mole percentage of CdCIz and

barying conccntrat~on of Li20 are shown in figures 3.1-3.4, and 3.8. The spectra

are similar to those of the ternary lithium borate glasses containing constant

concentration of LizO and varying concentrations of CdCI2 (Fig. 3.4-3.7)

indicating a structural similarity between the two sets of glasses (ie, structural

similarity betweei:~ the set of the four glass.sampies BCLS, BCL6, BCL7 and

tKL4 and the tivc glass samples BCLl, BCL2, BCL3, BCL4 and BCL8).

The spectra of BCLI and BCL2 contain absorption bands around 416, 425,

155, 509, 696. 783. 1026, 1103, 1212, 1361 and 1437 cin-' as in the case of BCLS

glass containing th,c slnallest concentration of CdCl?. These peaks correspond to

different types of structural groups and are assigned in the preceding section. Rut

if the LizO content is increased, several effects are observed in the IR spectra. 'l'he

main efkct 15 the cllsappcarance of the bands at 925, 1252, 1103 and 1435 cm-I for

Y > 0.10 mole percentage and higher concentration of Li20 (i.e. x > 0.15 mole

percentage) causes the disappearance of the band at 783 em-'

The spectrum of glass BCLl with x = 0.05 mole percentage gives a very

sharp and intense band at 783 cm" as ig the case of BCLS glass containing the

lowest concentration of CdC12, which is assigned to -0-B-0- out-of-plane bending

vibration of BO?' units in orthoborate group. Increase of x ( x = 0.10 inole

percentage) causcs the intensity reduction of this sharp band in BCL2 glass.

Further I.i20 addition (x = 0.15 mole percentage) causes the band at 783 em'' to

become very weak in BCL3 glass. Hence it may be inferred that higher

concentration of L120 (x > 0.15 mole percentage) causes the destruction of ~ 0 , ~ -

bearing group (orthoborate group).

The absencc of the peaks at 925 and 1103 cm-' for x > 0.10 mole

percentage strongly indicates the destruction of the Bod- tetrahedra in pcntaborate

and triborate groups respectively. In addition, the bands corresponding to the B - 0

stretching vibration of B-0-B linkages in boroxol and tetraborate groups (1252

en - ' ) and B 0 3 with NBOs (1437 cm") are absent for higher concentration of Li20

( X = 0.10 mole percentage).

It may thus be concluded that the glass samples containing 0.20 mole

percentage of CdCI2 and concentration of LizO up to 0.10 mole percentage

consists of ~01'. hearing unit (orthoborate), B04. tetrahedra (pentaborate, diborate

and triboratc). boroxol rings, triagonal ~ 0 3 ~ - units (metaborate, pyroboratc and

orthoborate) and l?;03 with NBOs. But when LizO concentration is increased (x >

0.10 nlole pcrcenlagc) some groups, such as bearing units (orthoborate),

H 0 4 containing triborate and pentaborate group, boroxol groups and BO, with

NBOs groups progressively get destroyed.

3 .4 . l . c Effect of variation in the concentration (x) of Li20 (0.10 < x 2 0.40)

tvl~en the co~~centration (y) of CdC12 (y = 0.10) was kept constant.

The composition of (1-x-y)(B203)-x(LizO)-y(CdClz) glasses used in the

present study is glven below while the observed band positions are tabulated in

table 3.4.

Sample code Mole % of Li20 Mole % of CdC1z Mole 'YO of B203

13CL9 0.10 0.10 0.80

BCL6 0.20 0.10 0.70

13CL10 0.30 0.10 0.60

15C1.1 1 0.40 0.10 0.50

rable 3.4 Observed 1R bands of ( l-~-y)(B~O~)-x(Li~O)-y(CdC1~) glass system for 0.10 x 2 0.40, y = 0.10.

Sample IR band position (ern.') 7 code

BCL9 417 433 454 508 696 782 925 1026 1102 1252 1356 1441 1630 3376

BCL6 417 418 468 496 692 783 1025 1369

BCLlO 417 431 457 508 698 1020 1377

BCLl l 418 431 482 508 704 1013 1407 3443

'The F'TIR spectra of the glasses containing 0.10 Inole percentage of CdClz

and varying concentration of Li20 are shown in figures 3.9-3.11, and 3.6. The

spectra are similar to those of the ternary lithium borate glasses containing

constant concentration 0.20 mole percentage of CdC12 and varying concentrations

of Li20 (Fig. 3.1-3.4 and 3.8) indicating. a structural similarity between the two

sets of glasses (i.e. structural similarity between the set of the five glass sarnples

BCLI, BCL2, BCL3. UCL4 and BCL8 and the set of four glass samples BCL9,

BCL6, BCLlO and 13C1,I 1).

The spectrum of BCL9 glass contains absorption bands around 417, 433,

454, 508, 698. 782, 925, 1026, 1105, 1252, 1356 and 1441 cm" as in the case the

case of BCI. I glass containing the smallest concentration of LizO and a constant

concentration of 0.20 mole percentage of CdC12. These peaks correspond to

different types of structural groups and are assigned in the section 3.4. l .a.

But if thc concentration of Li20 is increased, several effects are observed in

the lli spectra. 'l'lle main ones are the disappearance of the bands at 925, 1105,

1252 and 1441cni~' for x > 0.10. The disappearance of these bands indicate the

destruction of the I-IO,. tetrahedra containing pentaborate and triborate groups,

boroxol groups and DO3 triangle with NBOs as in the case of glasses containing

higher conccntra~ion of CdCI2. It is found that band around 782 cm-'

corresponding to ~ 0 ; ' - bearing orthoborate group, is absent in the spectrum of

UCLlO glass. The spectruln of BCL11 does not show a peak around 1370 cm-'

indicating the absence of ~ 0 , ~ - bearing units (metaborate, pyroborate, orthoborate

group). The band around 1440 cm" corresponding vibration of B 0 3 withNBOs is

absents in the spcctrum of BCL6 and BCLlO glasses and it reappear in the

spectrum of UCI. I 1 glass.

I t is concluded that in the glass system (lx-y)(B203)-x(Li20)-y(CdCI2) the

variation in the conccntration of CdCI2 does not affect the structure much while

the variation in the concentration of Li20.has profound influence on the structure.

3.4.2 (1-x-y )(B20,)-x(Li20)-y(ZnC12) glass system

3.4.2.a Effect of variation in the concentration (y) of ZnC12 (0.05 < y < 0.20)

when the concentration (x) of Liz0 (x = 0.20) was kept constant.

The details OF thc glass samples containing different concentrations (y) of

/,nC12 but conslant concentration (x) of Li20 used in the prcscnt study are given

below while the observed band positions are tabulated in table 3.5.

Sample code Mole % of LizO Mole % of ZnC12 Mole % of B203

HCL5 0.20 0.05 0.75

BCL6 0.20 0.10 0.70

I3CI,7 0.20 0.15 0.65

I3CL4 0.20 0.20 0.60

fable 3.5 Observtd l l i bands of (1-x-y)(B103)-x(Li20)-y(ZnCI2) glass system for

0.05 i 5 s 0.20, x = 0.20 --

Sample IR band position (cm.')

code

BZL5 416 4 2 5 4 5 2 508 695 782 924 1027 1105 1255 1356 1433 1651 3438

HZ1 6 416 422 454 508 698 783 924 1028 1105 1251 1360 1443 1651 3442

1 BZL7 406 425 453 508 690 1026 1365 1651 3449

1 BZL4 417 42' 457 509 693 1016 141 1 3442

The I.'TlR spcctra of the ternary glass sample BZL5 containing the lowest

concentration of 0.05 mole percentage of ZnClz is shown in figure 3.17. The

spectrum exhibits rlnany spectral features amongst which the most prominent are

the intense absorption bands at 695, 1027, 1356 cm-' and weak shoulders at 782,

024, 1105 and 1255 cm'l. Kamitsos et all' has reported that the low frequency

region of thc miti-infrared (550-800 cm-') spectrum of B203-Li20 glass is

dominated by bending vibrations of various borate units. The strongest feature of

the mid-infrared spectrum of B203-Li20 glass with low LizO content is a single

band at 700 cm-' tiue to bending of B-0-B linkages of the B-0 network. For

higher concentration of Li20, two well,separated bands at 708 cm-' and 765 cm"

are observed"'. The 765 em-' band increase in intensity, relative to that at about

700 ern-': until they merge to form one band and then increase in intensity and

tiqucncy with increase in concentration of Li20. The spectra of both 2Li20.B203

and 3 Li20.U2O3 show bands in this region, at 755 cm-' and 775 cm" respectively,

which may be assigned to -0-B-0- out-of-plane bending vibration of ~ ~ 0 ; -

(pyroborate) and ~ 0 3 ' - (orthoborate) units. Thus, the 760 cm.' band of the glasses

indicate the prescnce of ~ 1 0 5 ~ - and I or ~ 0 3 ~ - units. A weak band at 650cm-' is

probably due to the B-0-B in-plane bending vibration of ~ 2 0 5 ~ - (pyroborate) and

130,'- (orthoboratr) units. The sharp peak at 695 cm'l in figure 3.17 which is close

to the 700 cm-' band in the spectrum of low Li20 content B~o~-L~?o ' , is assigned

to bending of B-0-B linkages of the B - 0 network. The weak shoulder at 782cm'',

which is close to {.he strong band at 775 cm'l of B203-Li20 glass containing high

concentration of Li20 is assigned to '0-B-0- out of plane bending vibration of

~ 0 ~ ' - (orthoboratc) units.

It is now w~dely accepted33 that the broad band structure in the region 1150-

1500 cnl-I is due to B - 0 band stretching of B 0 3 units while that in the region 850-

1100 c ~ n - ' is attributed to the B-0 stretching of B 0 4 units. In the absorption

region of B 0 4 , three bands are evident at 880, 1056 and 900 - 1000 cm-I.

Crystalline tetraborate compounds show strong bands at 880 and 1020 cm'l, while

the lithium diborate compound absorbs strongly at 970 cm'l. Thus both 880 and

1050 cm-' bands are assigned to B 0 4 vibration of tetrahedra (triborate,

pentaborate) groups. Kamitsos et all' has reported that the bands at 871, 965 and

1060 cm-I are due to vibration of borate arrangements containing BO4. tetrahedra

(pentaborate. diborate and triborate) respectively. The analogous vibrations of

1304 tetrahedra belonging to diborate groups give rise to an absorption in the 900-

1000 cm-I region. In thc present study (Fig. 3.17), the absorption peaks around .

r 105, 1027 and 5124 cm-' are attributed to vibration of borate arrangements

containing BO4. tetrahedra in triborate, diborate and pentaborate groups

respectively.

In the case r'l'zinc bordte glass8 containing, PbO, the I I i absorption band at

1340 cm-I is assigned to B-0 stretching vibrations of triagonal ~ 0 ~ ' - units in

metaboratcs, pyrobosates and orthoborates. In comparison with the 1340 cm-'

band in zincborate glass. the broad and intense peak around 1356 cm-' (Fig. 3.17)

in the present study is assigned to B - 0 stretching vibration of triagonal ~ 0 3 ' - units

in metaborate, pyroborate and orthoborates. The shoulder at 1255 cm-I in figure

3.17 is close to the 1250 ern-I band in the IR spectrum of xMg0-yNa20-B203

glasses28. This band is assigned to a B - 0 stretching vibration of B-0-B linkages,

~nvolving mainly boroxol and tetraborate groups.

In the case of lithium borate glass33 containing, Li2S04, the IR absorption

band at 1430 cm-I 1s assigned to B 0 3 with NBOs. It is evident that, for this glass,

NBOs are formed at the expense of BOj and B 0 4 units. In the present study, the

IR absorption peak observed at 1433 cm" for the glass of composition 0.75 B203-

0.20Li20- 0.05 ZnCI,, is close to the band at 1430 cm-' of the spectrum of lithium

borate containing lithium sulphate. This band is attributed to B 0 3 units with

NBOs.

~arte' ' ' has concluded that Li04 tetrahedra give bands in the 400-550 cm'

'region. It is reporled 11.35-37 that silnultaneous occurrence of peaks around 239,

410 and 475 cm-' i:j a reliable proof of the presence of vibrations of ~ i ' cations

against their network sites. It is also rkported that8 the shoulder at 450 cm" in the

spectra of Zn0-Pb01-B203 glasses can be attributed to vibrations of metal cations

such as pb2' or %n2'. In the present study (Fig. 3.17), the bands at 416, 425 and

508 cm-' are attributed to the vibrations of ~ i + cations against their network and

the comparatively stronger band of 452 cm" is attributed to vibration of the zn2'

metal cations.

The FTlR spectra of the glass samples (BZL6, BZL7 and BZL4) containing

higher concentration of ZnClz (y > 0.05 mole percentage) are shown in figures

3.1 8, 3.19 and 3.15. All the spectra contain the absorption bands around 416,425,

452, 508, 695 and 1027 cru-' as in the case of BZLS glass containing the smallest

concentration of ZnClz. Hence the assignments of these bands are identical to

those mentioned in the preceding paragraph. It may be concluded that the same

structural units are present in the glasses containing different concentrations of

ZnCI2. But it is observed that the increase in concentration of ZnCI2 (y > 0.10)

causes the destruction of bands at 782,924, 1105 and 1255 cm".

The spectrum of the glass with y < 0.10 mole percentage gives one sharp

band at 698 cm-' and a shoulder at 783 cm-'(fig 3.12 and 3.13). The 698 cm-I

hand increases in intensity with increase in ZnC12 concentration and the shoulder

merges with this b,md resulting in a single IR absorption peak at 690 cm-' at y =

0.15 mole percentage. At y = 0.05 mole percentage there is a main band at 1027

cm-' and two weaker bands at 924 and 1105cm". Increase of y causes these bands

to overlap to give a broad band around 1026 cm" in the sample BZL7 and around

1016 cm-' in the sample BZL4. This band, as in the.case of BZLS, is assigned to

vibration of borate arrangements containing Bod7 tetrahedra (diborate, triborate

and pentaborate).

The band around 1433 cm" corresponding to vibrations of B 0 3 with NBOs

is absent in the spectrurn of BZL7 and it reappear in the spectrum of BZL4. It was

also found that thr band around 1356 cm-' corresponding to B - 0 stretching

v~bration of ~ 0 3 ' . units (metaborate, pyroborate, orthoborate) is absent in the

spectrum of BZL4 glass. The absorption bands around 1600 and 3429 cm-I in the

spectra of (1-x-y)(R203)-x(Li20)-y(ZnCl2) glasses are due to the 0 -H stretching

vibrations. The presence of OH' groups may be due to the incorporation of

moisture during sample preparation for FTIR spectroscopy.

Irion and ~ o u z i ~ " has reported that, the addition of LiCl to B203-Li20 glass,

does not produce any changes in the Raman and IR spectra of binary lithium

borate glass. 11 ma) thus be concluded that the presence of chlorine does not

produce any major modification in the vitreous boron-oxygen network.

20.11 . In compari:ion with the reported spectra of binary and ternary glasses , it

may be concluded that the structure of the (1-X-y)(B203)-x(Li20)-y(ZnC12) glasses

with the composition x = 0.20, 0.05 I y I 0.20 consists mainly of a continuos

random network containing boroxol rings, BOi tetrahedra containing triborate,

diborate and pentaborate groups and ~ 0 ~ ~ . containing orthoboratc groups. ,l'he

peak of appreciable intensity around 1433 cm" strongly indicated that NBOs are

formed at the expense of B03 and B04 units.

.3.4.2.b Effect of variation in the concentration (x) of Li2O (0.05 < x $ 0.20)

when the concentration (y) of ZnC12 (y = 0.20) was kept constant.

The details of thc glass samples containing different concentration (x) of .

1 i20 but constant concentration (y) of ZnClz used in the present study are given

bclow while the observed band positions are tabulated in table 3.6.

Sample code Mole % of Li20 Mole % of ZnClz Molc O/U of' B203

RCL l 0.05 0.20 0.75

UCL-2 0.10 0.20 0.70

BCL3 0.15 0.20 0.65

BCLJ 0.20 0.20 0.60

BC1-8 0.25 0.20 0.55

[able 3.6. Observc,d IR bands of (1-x-y)(B203)-x(Li20)-y(ZnC12) glass system for

0.05 i x < 0.20. y = 0.20

~. [ Sample IR band position (cm.')

1 code

1 BZL l 4 1 7 T .458 507 696 783 925 1026 1103 1252 1360 1437 1630 3436

The FI'IR spectra of glasses containing 0.20 mole percentage of ZnCI2 and

Larying concentrat~on of LizO are shown in figures 3.12-3.16. The spectra are

similar to those of the ternary lithium borate glasses containing constant

conccntrat~on of Ll20 and varying concentrations of ZnC12 (Fig. 3.17-3.19,3.15)

indicating a struct~~ral sinlilarity between the two sets of glasses (ie, structural

s~milarity belwecn ihc set of the four glass samples BZLS, BZL6, UZL7 and BZL4

and the five glass samples BZL1, BZL2, BZL3, BZL4 and BZL8).

The spectra of IJZL1, BZL2 and BZL3 contain absorption bands around

417, 441, 458. 507. 696. 783, 925, 1026, 1103, 1252, 1360 and 1437 cm-' as in the

c ~ ~ s e of UZL5 glass containing the slnallest concentration of ZnClz. 'l'hese peaks

correspond to different lypes of structural groups and are assigned in the preceding

section.

If the LizO content is increased, several effects are observed in the IR

spectra. The main effects is the disappearance of the bands at 783, 925, 1103,

1252 and 1360 cm-' for s > 0.15 mole perckntage and higher concentration of Li20

(i.e. x > 0.20 mole pcrccntage) causes the disappearance of the band at 1437 cm-'

~ ~ l s o . The spectrum of glass BZLl with x = 0.05 mole percentage gives one very

sharp and intense band at 783 cm'l as in the case of BZL5 glass containing the

lowest concentration of ZnCl*, which is assigned to -0-B-0' out-of-plane bending

vibration of U O ~ ' units in orthoborate group. Increase of x (x = 0.10 mole

percentage) cause:; the intensity reduction of this sharp band in BZL2 glass.

Further LizO addition (x = 0.15 mole percentage) causes the band at 783 c~n-I to

hecome very weak in BZL3 glass. Hence it may be inferred that higher

concentration of LizO (x > 0.15 mole percentage) causes the destruction of ~ 0 , ~ -

bearing group (orthoborate group).

The absence of the peaks at 925 and 1 103 cm-I for x > 0.15 mole

percentage strongly indicate the destruction of the Bod- tetrahedra in pentaborate

and triborate groups respectively. In addition, the bands corresponding to the 13-0

stretching vibration of B-0-B linkages in boroxol and tetraborate groups (1252

c ~ n - ' ) are absent fbr higher concentration of LizO (x = 0.15 mole percentage). The

band around 1360 cnl-' corresponding to B - 0 stretching vibration of ~ 0 3 ~ ' unit

cn~etaboratc. pyroborate, orthoborate groups) is absent in the spectrum of BZL4

and it reappear in the spectruln of BZL8 glass. It was also found that the band

round I437 tin-' corresponding to B 0 3 with NBOs vibration is abscnt in the

spectrum ofHzI.X glass.

I t Inay thu:j be concluded that the glass samples containing 0.20 nlole

percentage of Z11CI2 and concentration of Li20 up to 0.10 mole percentage consists

of EiOl3. bcaring unit (orthoborate), Bod- tetrahedra (pentaborate, diborate and

ribo orate), boroxol rings, triagonal ~ 0 , ~ - units (metaborate, pyroborate and

orthoborate) and BO; with NBOs. But when ~ i ~ ~ c o n c e n t r a t i o n is increased (x >

0.15 mole percenlage) some groups, such as ~ 0 ~ ~ - bearing units (orthoborate),

1 3 0 4 containing triborate and pentaborate groups, boroxol groups and DO3 with

Nl3Os groups progl-cssively get destroyed.

3.4.2.c 1Cffec.t of variation in the concentration (x) of Li10 (0.10 I x < 0.40)

when the concentration (y) of ZnC12 (y = 0.10) was kept constant.

The compo:jition of (1-x-y)(B203)-x(Li20)-y(ZnC12) glasses used in the

present study is given below while the observed band positions are tabulated in

able 3.7.

Sample code Mole % of Li20 Mole % of ZnClz Mole % of B2O3

UZL9 0.10 0.10 0.80

BZL6 0.20 0.10 0.70

13ZL 10 0.30 0.10 0.60

I3LL I I 0.40 0.10 0.50

rable 3.7 Observed I11 bands of (1-x-y)(B203)-x(Li20)-y(ZnC12) glass system for

0 . l O i s i 0 . 4 O , y = 0 . 1 0 . ~p

' Sa~ilple IR band position (cm.')

code ~-

RL1.9 417 425 451 507 696 782 ,925 1026 1103 1252 1359 1441 1651 3442

B Z L 6 416 122 454 508 698 783 924 1028 1105 1251 1360 1443 1651 3442

BZLl0 41: 426 452 500 703 939 1031 1384 3486

BZLll 417 139 460 503 710 1016 1425 3455

The FTIR spectra of the glasses containing 0.10 mole percentage of ZnC12

and varying concentration of Li20 are shown in figures 3.20-3.22, and 3.18. The

spectra are similar to those of the ternary lithium borate glasses containing

constant concentration 0.20 mole percentage of ZnC12 and varying concentrations

of Li20 (Fig 3.12-3.16) indicating a structural similarity between the two sets of

glasses (i.e.. structural similarity between the set of the five glass samples BZLI,

13ZL2, BZL3. HZ1.4 and BZL8 and the set of four glass samples BZL9, BZL6,

I3LL I0 and HZL 1 I ) .

The spectra of BZL9 and BZL6 contains the absorption bands around 417,

425, 451, 507, 696.. 782. 925, 1026, 1103, 1252, 1359 and 1441 cm" as in the case

of HZLl glass containing the smallest concentration of Li20 and 0.20 mole

percentage of ZnC:I2. These peaks correspond to different types of structural

groups and are ass~gned in the section 3.4.2.a.

If the L,izC:l content is increased, several effects are observed in the IR

spectra. The main effects are the disappearance of the bands at 782, 925, 1103,

1252 and 1441c1n.l for x > 0.20. The disappearance of these bands indicate the

destruction of the BO;.' bearing units (orthoborate), B 0 i tetrahedra containing

pentaborate and triborate groups, boroxol groups and B 0 3 triangle with NBOs as

In the casc of glas:ies containing higher concentration of ZnC12. The spcctruni of

BZL11 does not show a peak around 1359 cm-I indicating the absence of ~ 0 3 ~ -

bearing units (metaborate, pyroborate, orthoborate group). The band around 1441

cm-' correspondin vibration of B 0 3 with NBOs is absent in the spectrum of

UZL10 glass and i ~ . reappears in the spectrum of BZL11 glass.

It may thus be concluded that the glass samples containing low

concentration of'%nClz (y = 0.10 mole percentage) and concentration o f L i 2 0 up to

0.20 mole percentage consists of ~ 0 ~ ~ ' bearing unit (orthoborate), BO; tetrahedra

(pentaborate, diborate and triborate), boroxol rings, triagonal ~ 0 3 ~ . units

(metaborate. pyroborate and orthoborate) and B 0 3 with NROs. It is concluded

that in thc glass system (Ix-y)(B203)-x(Li20)-y(ZnC12) the variation in the

concentration of ZnCl? does not affect the structure of the glass much while the

ariation in the concentration of LizO has profound influence on the structure.

3.5. General discussion

The FTIR spectrum of the glasses (1-x-y)(B203)-x(Li20)-y(MCL2)

(M=Cd,Zn) containing different concentration of the constituents have been

recorded. The spectra have been discussed in the light of the spectra of reported

binary and ternary glass systems. The structure of .vitreous B203 is a continuos

random network ol' boroxol rings. It is reported that the most obvious effect of

adding Li20 to B:!03 is the systematic formation of and then destruction of

pentaborate, tetraborate, diborate, pyroborate, and orthoborate groups. These

groups have been found to be the main constituents of the borate network. Other

groups, such as rinp, type metaborates, are also presented in smaller amounts.

The addition of Li20 is seen to affect the structure of the ternary glasses

\'cry much in the present study. It was seen that in glasses containing small

conccntration (0.05 molc %) of Li20, the structure is built up of random nctwork

of ~0; ' - bearing metaborate. pyroborate and orthoborate groups, B04- tetrahedra

containing diboratc, triborate and pentaborate groups, and a fewer number of other

groups like UO, with NBOs and boroxol rings. Larger concentration of Li20

(0.40 mole %) causes almost complete destruction of the boroxol groups, ~ 0 3 ~ -

bearing orthoborale. pyroborate and metaborate groups, B04- tetrahedra containing

pentaborate and triborate groups. This indicates that the variation of concentration

of Liz0 in the ternary glass system B203-Li20-MC12, (M = Cd, Zn) has a profound

influence on the structure of the glasses.

11 is concluded that in the glass system (lx-y)(B203)-x(Li20)-y(MCI2), (M

= Cd, Zn) the variation in the concentration of CdC12 or ZnC12 does not affect the

structure of the glass much while the variation in the concentration of Li20 has

profound inlluence on the structure.

3.6. Conclusion

The F'fIK spectra of the ternary glasses (lx-y)(B203)-x(Li20)-y(MCI2),

(M=Cd,Zn) were recorded. The features of the spectra were discussed in the light

of reported spectra of binary and ternary glasses. The concentration variation of

l i20 in the glasses was found to induce a systematic destruction of boroxol

groups, ~ 0 ~ ' - bearing orthoborate, pyroborate and lnetaboratc groups, and BO4-

tctrahedra contain~ng pentaborate, and triborate groups. The variation of

concentration of C'dC12 or ZnC12 in the glass sarnples was found to have no

profound intluence on the structure of the glasses while the structure was decided

~nainly by the concelltration of Li20. The FTlR spectra of all the glass salnples

analysed in the prerent study indicated the random nature of the network of the

glasses.

References

I . 1'. J . Bray and J . C;. O'Keefe, Phys.Chem. Glasses, 4, 37(1963)

2. G. E. Jellison and P. J . Bray, .I Non-Cryst. Solids, 29, 187(1978)

3 P. J . Bray, J Nun-Cryst. Solids, 73, 19(1985)

4 1'. W. Brill. l'l~iiips Res. Rep: Suppl, No.2 (1976)

5 W. L. Koni,jinen~:ii.jk and J . M. Stevels, JNon-Cryst.Solids, 18, 307(1975)

6 J. Krogh-Moc, /''hyys. Chem. Glasses, 6 , 46(1965)

7 J . Wong and C A. Angell, Glass structure by Spectroscopy ( Dekker, Now

York, 1976) ch.'

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