X-ray and neutron diffraction analyses of barium silicate glass

201

X-RAY AND NEUTRON DIFFRACTION

Hiroshi

HASEGAWA and

Institute

Itaru

ANALYSES OF BARIUM SILICATE

YASUI

of Industrial Science, University of 7-22-l. Minato-ku, Tokyo 106, Japan

Roppongi

GLASS

Tokyo,

Neutron diffraction of BaO.2Si02 glass was measured by use of a pulsed spallation neutron source and a steady reactor. The structure of the glass has been analyzed by a pair function method on obtained RDFs. The informations concerning to glass former consisting of light atoms 0 and Si appear clearly in the ROF obtained from the neutron diffraction, complementary to the RDF obtained by X-ray diffraction. As a result, in this glass the Si04 tetrahedra form six-membered rings constructing strongly folded layers and Ba atoms are located in holes formed between the layers.

1. INTRODUCTION Silicate

l/B0

containing

mole

silicate

glasses

aperture

number

only

are

useful

strongly the

folded

that

has

the

elements.

for

neutron

information bution

in

are

rather

of of 0,

On the

This

Ba atoms Si,

other

(cross-sections about

function

(RDF).

a pulsed

Si

atoms

Further,

neutron

the

14,

56)

be obtained

not.

the

by glass

the is

0.4149,

0.525) radial

very

fact large from

cross-sections

a neutron at

on

structural

informations

high

ROF in a small

It this

studies

of

comparable

from data

a sharp

However,

this

the

a single

folded2.

explained

hides

high is

whether

a part

of

Ba = 0.5805,

diffraction

with

strongly

only

have

with

EaO.ZSiO2

silicate

partly

and

Si,

to

very

that Barium

a waveguide

or

and

elements

condition

in airI.

hand,

of

is

0,

leads

is

glass few

the

cool

crystal

structure

can the

source

other

diffraction

all

of

0 and

glass,

X-ray

Ba = 8,

hand,

crown

situation to

in to

On the

anions the

presents

glass

vitrifies allowed

phyllosilicate

silicate of

obtained.

factors

the

anhydrous of

also

this

been

etc.

viewpoint

contribution

(scattering

with

of

an optical

form

layer

the

layer

structure

information

the

in

and

ceramics, to

and

interest

40 mole%

crucible as

or glass

cation

of

0 to

in a Pt-Rh

one among silicates

divalent is

BaO from

is melted

and

the

distri-

Q available

radius

range.

2. EXPERIMENTAL 2.1.

Preparation

A mixture at

1500

allowed water.

of

C for to The

of reagent

the

20 minutes cool weight

in

air of

sample

grade and to the

the

of

8aCO3

the

and Si02

crucible

temperature

production

0022-3093/87/$03.50 0 Elsevier Science Publishers (North-Holland Physics Publishing Division)

was melted

was

agreed

B.V.

taken

out

100 deg.

above

with

theoretical

in from

a Pt-Rh

crucible

a furnace

Tg and

dipped value

and into within

0.5wt%, The

so the

produced

composition glass

diffraction.

was

The

of

the

glass

pulverized

density

was

and

of

this

used

considered as the

glass

to

sample

measured

be accurate for

with

X-ray

and

by Archimedean

1%.

neutron

method

was

3.60g/cm3. 2.2.

X-ray

The with

X-ray

diffraction

measurement

diffraction

profile

a MO target

was

and an output

and

the

condition

for

this

glass

of is

of

measurement

shown

in

obtained

60kV,

using

130mA. The

were

reported

a Rigaku

method

of

Denki

Rotaflex

monochromatization The

previously3.

RDF obtained

Fig.1.

3100.

L a

FIGURE 1 The RDF of BaO.ZSiO2 obtained from X-ray tion data

,’ 6

glass diffrac-

o.ou: : : : : : ’ 2

2.3.

Neutron

diffraction

The

neutron

diffraction

pulsed

spallation

performed (KEK).

the

of

neutron Since

the

Fukunaga4,

with

experiment, The

metal

cylinder

and

set The

Research white,beam

the

High in

the

Intensity National

of

HIT

have

method.

The

a 4.5 m incident

sample

with

in a vacuum latter

was

Reactor from

was

reactor

path

the is

in mn,

measure of

Japan

the

inner total

has

150:

height diameter

scattering

a diffractometer Atomic

monochromatized

that

are

30:

of

is

23:

by con-

In

13Oand

40 mm in

8 mm and

used

measured

3He counters. 50:

this

8Owere

a vanadium

length

40 mn,

intensities. installed

Energy to

water is

and

beam from

spectrometer

fifty 90:

with

Physics

by Watanabe

by pure

a was

(HIT)

proton

neutron

40 mn. The

and

both

High-Energy

cooled

is

former

A pulsed

diffracted

of

stuffed

by use in

target the

of

The

elsewhere

below.

beam

angles

0.025 to

performed (JRR-2)

the

at

thickness chamber

of

flight

counterbanks

powder

and

by use

spectrometer for

reported

given

a uranium

height

out

reactor.

scattering

been

beam

carried

steady

Laboratory

is

and

a

Total

description

neutron

were

and

source

pulsed

seven

used.

source

synchrotron

the

time-of-flight structed

measurements

a brief

KEK booster

10

8

measurements

details

only

generate

6

neutron

by use

a pulsed

to

4 radius(A)

Research with

at

the

Institute. a wave

length

Japan The 1A by

reflection The

with

reflected

than

25'

and

thickness reaches angular lated

through

measured

in a step The

with reactor,

higher D,,,

tions

Q/Q

than

Q,

this

a measurement

graphite. JRR-2

and

the

obtained formed

those

by the to

was

was

from

30-50

steady

steps

28-17.17.

divergence

metal

cylinder

The

diffracted

40 mm.

angular

method were

114°(Q=0.4-10.5A-1).

neutron

wave

the

less with

a

beam

was

0.5"to The

provides with

adopted

Z'and

signal

the

accumu-

in

data

from

the

a steady

momentum

a small

resolu-

quantum

beam monochromatized obtained

with

normalized in

diffraction

a beam

1A. However, higher

data The

shown has

is

reactor's

HIT.

reactor

that

a little

steady

are

source

than

length

were

with

RDFs as shown

s,

A-I

we combined

reactor

a vanadium

length

angle

with

counts.

where

obtained

diffraction

A step-scanning

750

a pulsed

the

the

collimator

in

2'0=4"to

measurement with

steady

sample

40'-collimator.

i.e.,

Therefore, and

at

an open

12 mm and

time

with

= 12.5A-1 in

by

was 5 - 8x104

measurement

much

pyrographite

diameter

counting

range

of

collimated a powder

mm,

a counter fixed

plane is

illuminates

0.25

where

HIT

(002) beam

Fig.2(a),

which

low

resolution.

somewhat

the

intensity

range

by pyro-

diffractometer S(Q)s

indicates S(Q)s

in

obtained that were

by S(D)

trans-

in Fig.?(b).

1.5-

1.0.. FIGURE 2 The normalized intensities S(Q)s and RDFs of BaO.2SiO2 glass obtained from neutron diffraction data (a) the normalized intensities

. 5 ..

Q (4n/X-sine) I 5

10

15

radius(A)

20

25

30

S(Q)s ---

pulsed steady (b) RDFs pulsed --steady +pulsed

neutron reactor's

source source

neutron reactor's neutron

source source source

3.

THE STRUCTURES of BaSiBOS

with

is

the

a single

which

are

than

The

structure

by Douglass5 a1.7

Ba+B, of

form

these

of

and Hesse

and Hesse

consisting

of

to the

LiebauG.

six-membered

are

form,

sanbornite

known2.

SiO4

The

Ni+2

and Co'B,

no

crystal

have

been form

similar

layer

("zweier

has

two

form

has

high-temperature

tetrahedra

anhydrous

BaSi20S

high-temperature

sanbornite,

of

crystals

of

phyllosilicate

Mg+2, readily,

and

form,

and that

Those rings

anhydrous Cat2,

silicates

cations

LiebauG

form

cations

chain-type

low-temperature

and

and

silicates

Although

low-temperature

Fig.3).

et

among

cation.

silicates

polymorphs,

CRYSTALS

one

divalent

smaller

layer-type

BaSiBOS

only

(see

reported by Katcher

structures

single

layer"

in

-b I

FIGURE 3 Low-temperature form of BaSi205, sanbornite 7 (a) one tetrahedral layer projected parallel IO011 (b) the tetrahedral layers projected parallel [OTO)

the

nomenclature

layers.

The

degree the

of

fact

the

chain

ion

non-bridging

b-axis

and

and

the lies

a barium

the along

Liebau) of

folding

that

crystals,

of folding

is

are

layer

somewhere

in

between

considerably

oxygens point

Ba atoms

silicate

in

located both

that

of

larger the

up and down

the

athan

tetrahedra in

in

holes

crystals

is

and

the

despite In

ion.

up and

down

of

in

two

the

and

B-Na2SiBOS

a sodium

point

periodicity

between strong

the

both in

the

chain

along the

a-axis. rate

larger

form

the

in

than

thermal

high-temperature

six..In

in the

are

less

the

strongly

the

folded

-> high

form

the

latter

effective

form, the

those

in

symnetry

periodicity size

of

sanbornite,

tetrahedral

than

in a reduction

low

form

form,

Therefore,

results

during

this

low-temperature

vibration.

folding

4.

In

one

due

layers

to

in

broken

in

ions

is

increase

in

high-temperature

This

the

is barium the

the

in sanbornite. from

the

decrease

orthorhombic

in

to

layer

monoclinic

transformation2.

RESULTS The

peaks

which

other

practically.

X-ray

RDF and

RDF and

sharp

D pairs

and

(2.60A)

pairs.

D-D

pair,

RDF,

2.63A in

rable,

while of

position

the

RDFs

neutron

but

the

7.3A,

while

5.

STRUCTURE We have

Na20-, crystals

and

of

the crystals

such

a strongly

SiD4 At method shown

pairs

peak in weak in

neutron

shifted only

peak in

4.94A

two

peak

the

than

the

and

the

canpa-

greater

appeared

D-D

as an

are

times

Si-

and

In the

4.15A

a very

kinds

tetrahedron

and

the

mode

RDF for

the

some broadening calculated

disilicate These

the

in the

RDFs.

The

was recognized

same position.

with

of two

the pile crystals

parameters ROFs for

one

in

up of

is

the were

which both

there

it

is

the

layers

of

of

Si04

decrease

are

of

few

reports

Barium

disili-

interest

to

crystals

the

direction are

calculated increased

the

the

whether

or not.

similar

which

rings

with

cations.

and

glass

One

models. is

hand,

Li2D-,

corresponding

six-membered

divalent in

e.g.,

and

increases

above

presents

of

of

other

as described

glasses,

glasses

layers

On the

structure

two

The

of

glasses

ones

other

Fig.5.

O-D

reverse

consisting

folding

silicate

unique

the

in

several B,9.

cations.

and

the

seven

appeared

to

O-O pairs

to

the

X-ray

strong

pair.

and

at

the

(2.75A)

times

a Ba-0

third

peak

Ba-D

seven

appeared

5.3A and

of

the

strained

using

The

in

in

corresponds

of

Ba-0 of

are

above

structures

crystals

first

five

peaks

RDF a major

of

of

are

We constructed BaSi205

fifth

structures

monovalent

structures

about

intensities

layer-type

the about

of of

each

2.76A

shape

course,

about

peaks is

Li2D.K2D-disilicates

and a degree

cate

distance

of mixture

(at

AND DISCUSSION

the

tetrahedra radii

to

an D-O pair.

X-ray

ANALYSIS

have

is

2 correspond

peak

in a broad

contribution

and

relative

studied

K2D-

pair

and

second

peak,

a Ba-0

function

of

the

appear

first

the

in Fig.1 the

the

had details

in

RDF)

great

fourth

the

and

D-O pairs

so the

RDF scarcely

at

of

distance

RDF and

both

pair

number

ROFs

to

RDF,

the

the 1.60A

RDF. The

shifted

of

of at

corresponds

X-ray

pairs,

to

neutron

neutron

one

peak

the

Ba-0

the

neutron

the

strengths

both peak

second In

in

first

in

the

the

so this

the

that

appear The

structure

of

of

of

somewhat by a pair

with

atomic were

similar

bending different. function distance

as

to

each

other.

The

recognized

difference more

a sharp

peak

and

no peak

had

will

between

clearly

at

in

4.8A

where

at

4.2A

be attributed

to

the

the the

the

the

difference

of

crystals

the

showed

the

Ba-Ba

and

RDFs for

glass

RDF for

glass

for

the only

had

the

glass

crystals

was showed

small

shoulder,

a great

This

peak.

distances.

FIGURE 4 The RDFs calculated from the structures of BaSi2OS crystals ---low-temperature form .,.. high-temperature form BaO.ZSiO2 glass (observed)

L ,” N A

The

models

structed.

In

this

model,

as in

the

crystals.

tained and

the

RDF and

RDF for

where

the

RDFs for

X-ray

other

similar

parameters,

appropriate,

possibility Other

but

because value

due that

the

structures

symmetry

could

not

the

distances

a better of

model

direction

of

bending

so this

model

seems

of to

Si04

Fig.5

tetrahedra for

crystals Si04

angles

of

good

Ba-Ba

(model

of

agreement

We judged

of

might in

be suitable

bending

be found.

model

the

bending

showed

high

shown

of the

the

which

to relatively

kind

of

Varying a model

RDFs was searched

certain

to

pair

structure

that

A) was

tetrahedra the

Si04 with

this

tetrahedron the

observed

model

was

concentrate

symmetry,

con-

was main-

easily

although

not to

there

a is

be found. (model is

B) was

not

a model

examined.

so symmetric for

the

as the

In

this

model

above

model,

glass.

FIGURE 5 A structural model for BaO.2SiO2 glass tetrahedra: Si04 units 0: non-bridging oxygen atoms 8: barium ions

H. Hosegowo,

The not

calculated

obtained

In

this

model

This

means

that

of

RDFs

yet, Si04

that

the

this

I. Yosui / Ano!vs~s o/ hurium

are

shown

model

has

tetrahedra

the

layer

crystals

Fig.5.

Although

possibility

were structure

but

in

a strongly

to at

15"in

in

the

glass layer

207

sufficient

represent

bent

folded

silicore gloss

the

xy-plane is also

agreement glass

and

was

structure.

35'in

somewhat

different

presents

in the

yz-plane. from glass.

2500

FIGURE 6 The calculated RDF for the model B ---calculated for the model -observed (a) X-ray RDF (b) neutron RDF

0

2

4

6

B

B

radius(A)

ACKNOWLEDGEMENT We would University programs thank

like

to

thank

who helped for Dr.

the

M. Nishi

Tokyo,

who

helped

Energy

Research

Prof

us in

data in

treatment the

us in Institute.

. M. Misawa

neutron Institute

neutron

in

KEK and

diffraction and gave for diffraction

Dr. T. Fukunaga

measurement advice Solid

to

in

us. We would

State measurement

Physics, in

in Tohoku

KEK and also

provided like

University the

Japan

to of

Atomic

REFERENCES 1) M. Imaoka,

Glass

Handbook,

2) F. Liebau, Heidelberg,

Structural New York,

3) I.

H.Hasegawa

Yasui,

4) N. Watanabe,

T.

5) R. M. Douglass, 6) K.-F.

Hesse

7) H. Katscher, 8)

M. Imaoka,

9) N. Aoki,

and M.

Fukunaga

et

G. Bissert H.Hasegawa

al.

and and

et

Chem.

KENS Report

Berlin,

Glasses,

II

(1981)

539

153

(1980)

33

p.880

24

(1983)

65

517

Kristallogr.

I.Yasui,

(Asakura-Shoten.1975)

(Springer-Verlag,

Physics

F. Liebau,

I.Yasui,

al.

Silicates

43 (1958) 2.

and

Sakka

Imaoka,

Mineral.

F. Liebau,

H.Hasegawa

S.

Chemistry of Tokyo, 1985)

Amer. and

eds.

ibid.,

Physics

137 Chem.

Yogyo-Kyokai-Shi

(1973) Glasses 94

146 24

(1986)

(1983) 539

72