Electrical properties of AgGeSe films used in ion selective electrodes

CONDE GARRIDO, J. M.; MARIA ANDREA UREÑA; ARCONDO, B.

Buenos Aires

Congreso; At the Frontiers of Condensed Matter V; 2010

Chalcogenide glasses have been used as sensitive membranes in ion selective electrodes (ISEs) for more than three decades. Their chemical stability ensures high endurance even in aggressive acidic media and their remarkable glass forming ability enables the use of these materials, either as bulk or as thin films, in the development of sensitive membranes for micro-sensors or multi-sensor arrays. In order to understand the sensing properties of these materials it is necessary to know first its electrical properties. The bulk chalcogenide glasses Agx(Ge0.25Se0.75)100-x (0 at.% ≤ x ≤ 25 at.%) have been studied as sensitive materials for ISEs. For x ≥ 8 at.% the glasses exhibit sensibility to Ag+ and Cu2+ ions in aqueous solutions. For x < 8 at.% the electrode’s response was poor with almost no sensibility. On the other hand, this system behaves as ionic conductor (10-5 S/cm) for x ≥ 8 at.% and as insulator (<10-13 S/cm) for x < 8 at.%. Membranes with smaller resistance were prepared in order to study whether the sensibility of these materials is determined by the ionic conductivity exclusively or by the total electrical resistance of the membrane. Thin films of compositions Agx(Ge0.25Se0.75)100-x (0 at.% ≤ x ≤ 25 at.%) were deposited by PLD and the electrical transport of the films was analyzed by measuring the surface and bulk DC conductivity.