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Structural and physical characteristics of Au 2 O 3 ‐doped sodium antimonate glasses – Part II electrical characteristics
Author(s) -
Ashok Jujjavarapu,
Kostrzewa Marek,
Ingram Adam,
Nalluri Purnachand,
Venkatramaiah Nutalapati,
Srinivasa Reddy Maddireddy,
Ravi Kumar Vandana,
Veeraiah Nalluri
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16213
Subject(s) - antimonate , ionic conductivity , analytical chemistry (journal) , dielectric , ion , conductivity , relaxation (psychology) , ionic bonding , doping , electrical resistivity and conductivity , materials science , thermal conduction , chemistry , mineralogy , inorganic chemistry , antimony , composite material , electrode , optoelectronics , social psychology , psychology , organic chemistry , chromatography , electrical engineering , electrolyte , engineering
In continuation of our earlier investigations on structural and physical characteristics of Au 2 O 3 ‐doped sodium antimonate glass‐ceramics (Part‐1), in this part we have investigated the influence of gold ions on electrical characteristics of the Na 2 O–Sb 2 O 3 : Au 2 O 3 glass‐ceramics. The study contains the results of quantitate investigations on dielectric properties, impedance spectra and A.C. conductivity in larger ranges of continuous frequencies (4 Hz‐8 MHz) and temperatures (300‐630 K). The variations exhibited by dielectric parameters with temperature and also with frequency were discussed in terms of various polarization mechanisms. The observed dielectric relaxation effects were analyzed using pseudo Cole‐Cole plot method and the analysis indicated spreading of relaxation times for dipoles. A.c. conductivity and also d.c. conductivity were found to decrease (to three orders of magnitude) with increase in Au 2 O 3 concentration upto 0.1 mol%. The decrement is ascribed to the increasing concentration of Sb 5+ ions that were predicted to participate in the glass network forming with SbO 4 units. Even though, both ionic and polaronic contributions are possible for conduction in the studied material, quantitative analysis of these results indicated that the polaronic conduction (due to intervalence transfer between Sb 3+ ↔ Sb 5+ and Au 0 ↔ Au 3+ ) is prevalent. The results have also suggested that there is a gradual decrement in the ionic component with increase in Au 2 O 3 concentration. Variation in σ ac in the low‐temperature region could satisfactorily be explained using quantum mechanical tunneling (QMT) model. Analysis of the results of d.c. conductivity indicated that the small polaron hoping (SPH) model is valid, especially in a high‐temperature region while the low temperature part of d.c. conductivity is analyzed based on variable range hopping (VRH) model. Overall, the increase in Au 2 O 3 dopant concentration in the studied glass‐ceramics caused a decrement in the magnitude of the conductivity or increase in the insulating strength of the material.