Compositional dependence of the electrical conductivity in silver containing chalcogenide glasses

V. Ilcheva

1,2

, P. Petkov

1

, I. Kanazirski

3

, E. Lefterova

2

,T. Petkova

2

1 University of Chemical Technology and Metallurgy, Department of Physics, Sofia, Bulgaria 2 Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, Sofia, Bulgaria 3 University of Mining and Geology “St. Ivan Rilski” 1700 Sofia, Bulgaria

e-mail: [email protected]

Abstract

We present the results from conductivity measurements of three different compositions in the chalcogenide glassy system As-Se-Ag. The aim of this work is to study the influence of the Ag addition on the conductivity of the system as a result of modification of the glass structure.

(AsSe) 100-x Ag x glasses (x = 15, 20, 25 mol %) were prepared by melt-quenched technique. Impedance Spectroscopy Method was applied to determine the electrical conductivity of the glasses. The measurements were performed in the frequency range 1 Hz to 1 MHz at different temperature. The compositional dependence of the glass conductivity was investigated and discussed.

EXPERIMENTAL RESULTS Compositions



(AsSe)

85

Ag

15



(AsSe)

80

Ag

20



(AsSe)

75

Ag

25 (AsSe) 100-x Ag x 6,0x10 4 4,0x10 4 2,0x10 4 4,0x10 6 0,0 0,0 2,0x10 4 4,0x10 4 Z',



6,0x10 4 2,0x10 6 (AsSe) 85 Ag 15 (AsSe) 80 Ag 20 (AsSe) 75 Ag 25 0,0 0,0 2,0x10 6 4,0x10 6 Z',



6,0x10 6 8,0x10 6

Impedance spectra of the of (AsSe) 100-x Ag x glasses at T = 20˚C

2,0x10 4 20 o C 40 o C 80 o C 120 o C 0,0 0,0 4,0x10 6 2,0x10 4 Z',



4,0x10 4 2,0x10 6 4,0x10 5 2,0x10 5 0,0 0,0 2,0x10 5 4,0x10 5 6,0x10 5 Z',



8,0x10 5 1,0x10 6 1,2x10 6 0,0 0,0 2,0x10 6 4,0x10 6 Z',



6,0x10 6 8,0x10 6

Impedance spectra of the of (AsSe) 80 Ag 20 temperatures glasses at different

x=5 1x10 -2 x=25 1x10 -3 10 20 30 40 50 2



, deg

XRD spectra of (AsSe) 100-x Ag x glasses

60 Composition (AsSe) 85 Ag 15 (AsSe) 80 Ag 20 (AsSe) 75 Ag 25 Conductivity (20˚C) S.cm-1 3.2x10

-5 7.8x10

-4 3.0x10

-4 Ea eV 0.64

0.29

0.53

1x10 -4 (AsSe) 85 Ag 15 (AsSe) 80 Ag 20 (AsSe) 75 Ag 25 2,4 2,6 2,8 3,0 1000/T , K -1 3,2

Arrhenius plot for (AsSe) 100-x Ag x glasses

3,4

SUMMARY

Chalcogenide glasses (AsSe) 100-x Ag x in the compositional region of x = 15 – 25 were prepared and characterized. The experimental impedance data were analyzed and the bulk conductivity was estimated, using two different models. The conductivity is found to increase with increasing silver content and temperature. This is probably due to modification of the glass structure as a result of formation of AgSe, improving the ionic conductivity of the material.

The results show higher values of the conductivity and lower activation energies, compared to our previous investigations in the As-Se system, containing AgI.

Acknowledgment: The authors are grateful for the final support of European Social Fund, Human Resources Development Programme, under the contract BG 051PO001-3.3.06-0014