TSC measurements of sodium borosilicate glass irradiated with X-rays

Journal of Electrostatics, 23 {1989) 391-394 Elsevier Science Publishers B.V., A m s t e r d a m - - P r i n t e d in T h e N e t h e r l a n d s

TSC MEASUREMENTS

OF SODIUM BOROSILICATE

391

GLASS IRRADIATED WITH X-RAYS

E. RYSIAKIEWICZ-PASEK Institute of Physics, Technical 27, 50-370 Wroclaw (Poland)

University

of Wroclaw,

Wybrzeze

Wyspianskiego

SUMMARY The thermally stimulated currents in electrically polarized and X-ray irradiated sodium borosilicate glass were investigated in the temperature range between i00 and 380 K. One TSP peak (for X-ray irradiated glass) and one TSD peak (for both electrically polarized and irradiated glass) were observed. The origin of these peaks is proposed.

INTRODUCTION Solid dielectrics, as

a

result

exhibit

of

such as borosilicate

irradiation

a behaviour

similar

with

gamma,

to electrets.

the irradiated glasses produces

results

for

X-ray

irradiated

of the measurements

electrically

electrons

The release

of measurements

sodium

borosilicate

are compared

obtained for the electrically

or

with

polarized

(ref.

i).

of the trapped

a thermally stimulated peak (ref.

In the present paper the results currents

glass, become X-rays

are

the results

in

2).

of the thermally glass

They

charge

stimulated

presented.

The

of the measurements

polarized glass sample.

EXPERIMENT The subject of investigation composition The device

measurements consisting

were irradiated The

X-ray

thermally

was sodium borosilicate

(percentage by weight): of

the

thermally

of an TSC

cell,

glass with the following

20~ Na20, 40~ B203, 40~ SiO 2. stimulated

vacuum

system

currents

were

at i00 K by an X-ray lamp (tungsten cathode,

irradiated stimulated

samples currents

were were

not

preheated.

performed

performed

and electrometer.

in the

The

The

in a

samples

I=i0 mA, U=50 kV).

measurements

temperature

range

of

I00 and 380 K. Either graphite or gold paste electrodes were used. Dimensions the samples were lOxlOxl mm. The samples were ground from both sides.

0304-3886/89/$03.50

© 1989 Elsevier Science Publishers B.V.

the

between of

392

10-7 A 10-8

10.9

10-1o

I0-11

1042

1043

I

10-1~

T

I

180

I

I

I

I

220

260

300

340

Fig. I. TSP curves. (a) Non-irradiated sample. (b) The sample irradiated with X-rays

I

380 K

at i00 K, E = 2.105 V/m. P

AfI

10-11

lO-~2I

1°-'~/~10-1~

I

I

I

I

I

180

220

260

300

340

I

T

380 K

Fig. 2 . Radiation-stimulated polarization. TSC curves. (a) The sample irradiated at i00 K with X-rays. (b) ~ h e sample irradiated at i00 K with X-rays with 2. I0-- V/m),

an

electric

field

(E =

P

393

RESULTS Figure 1 shows

the TSP curves for (a) the non-irradiated

sample,

sample irradiated with X-rays at I00 K. During heating an external was

applied.

For

the

non-irradiated

glass

there

were

no

and (b) the

field (200 V)

peaks,

but

for

the

irradiated glass one peak appeared at 280 K. Figure X-rays,

2 shows

and

(b)

field applied. energy

for

technique

the TSC the

curves

sample

for

irradiated

One peak was observed

irradiated (ref.

3).

glass

The

(a)

was

values

the sample

with

X-rays

irradiated at

at a temperature

determined

of

the

i00 K with

i00 K with

an electric

of 280 K. The activation

applying

activation

at

the

energy

partial for

discharge

the

subsequent

cycles were: 0.57, 0.69 0.71, 0.71, 0.73 eV. The results of TSP/TSD measurements for this glass are described elsewhere

(ref. 4).

DISCUSSION Irradiation

of

dielectrics

storage and polarization In

the

investigated

by

ionizing

radiations

glass

one

X-rays at i00 K with an electric

peak

appears

field applied

for

can

[B04]

be

connected

tetrahedra.

It

with is

polarization

exists

nonbridging

oxygen ions

the

also

induce

the

related [NBO]

to

the

that

of

in

sodium

glass

irradiated

observed

on the TSP curve

measured

current

current

for the

appearance dipole

the

this

ion

sodium

glass

(Na +)

an

ions

irradiated

concentration

of

the

0.25 h, X-ray suggest

sample.

jumps

glass

glass

A decrease

(Fig.

is lower

around

i).

The value

of the

the value

of

in the measured can be related

in dc conductivity.

but is not

current

field

applied

for

the

(Fig.

by X-rays,

and the

It is also possible

in

that

electrically

irradiated with and

2) does not change or electric

polarized

with

experimental

polarization.

glass

that the nature of the peak for electrically

for X-ray irradiated

conductivity

the

to an increase

sample

The height

(Tp= 210 K,

E = 2.105 V/m) (ref. 4) is lower than the height of this peak P irradiation with electric field applied (Ep= 2.105 V/m). These

can

the

than

of the peak maximum for the glass sample

such as irradiation

concentration It

for non-irradiated non-irradiated

or decrease

the electric

peak

around

orientational

appear.

The temperature

conditions

This

(ref. 4-6).

of the peak after X-ray irradiation

both mechanisms

without

the

with

2). At the same temperature

The peak on the TSP curve for the irradiated glass sample appears,

for

charge

polarized glass sample.

reorientation

possible

the

(Fig.

(280 K) a TSD peak is observed for the electrically peak

can

effect.

glass is identical,

polarized

tp= after facts

glass sample and

but after X-ray irradiation

the dipole

increases.

be,

therefore,

suggested

in the non-irradiated

that

the

sodium

ions

glass are, after irradiation,

taking

part

in

bound with some

394

elements

of the glass

structure.

These

defects

and

form so-called

thermal

defects

in

glass

are

[BO4]

Irradiation

with

X-rays

X-rays

the

dipole

the

groups

stimulates

concentration

ions associate

dipoles

these

(ref. or

7).

with the glass The

non-bridging

processes.

in the glass

mentioned oxygen

After

increases

structure structural

ions

[NBO]

irradiation

and intercepted

.

with sodium

ions do not take part in conductivity.

ACKNOWLEDGEMENT I would

like to thank Dr. V. Graveris

Solid State Physics,

University

and I. Krumins

of Riga (Soviet Union)

from the Institute

of

for making it possible

to

perform the measurements.

REFERENCES

i

2 3 4 5 6 7

B. Gross, Radiation-Induced Charge Storage and Polarization Effects, in G.M. Sessler (Ed.), Electrets, Springer-Verlag, Berlin-Heidelberg-New York, 1980, pp. 217-284. C.M. Hong, D.E. Day, R.A. Weeks, D.L. Kinser, J.Non. Cryst. Sol., 46 (1981) 389. C. Bucci, R. Fieschi, G. Guidi, Phys.Rev., 148 (1966) 816. E. Rysiakiewicz-Pasek, V. Graveris, I. Krumins, in preparation. R.L. Myuller, Elektroprovodimost stekloobrazyyushchikh veshchestv, Ed. Leningradskii Universitet, Leningrad, 1968, pp. 5-145 (in Russian). B. Dutta, D.E. Day, J.Non. Cryst. Sol., 48 (1982) 345. Yu. Gorokhovatsky, Osnovy termodepolyarizatsionnogo analiza, Ed. Nauka, Moskva, 1981, pp. 115-120 (in Russian).