New membrane material for thallium (I)-selective sensors based on arsenic sulfide glasses

• Synthesis of new chalcogenide glass materials for the Tl-selective chemical sensor.
• Diffusion of radioactive tracers 108mAg and 204Tl in TlI-Ag2S-As2S3 was studied.
• Diffusion coefficients of Ag+ are three orders of magnitude higher than for Tl+.
• Chalcogenide glass 27 TlI-20 Ag2S-53 As2S3 (mol%) is the best Tl-membrane.

New membrane materials were studied for thallium (I)-selective chemical sensors based on chalcogenide glasses in the TlI-Ag2S-As2S3 system. Using these studies on the radioactive tracers diffusion (108mAg и 204Tl) and electrical conductivity, an ionic conductivity of σion = 10−7 Ohm−1 cm−1 (20 °C) was found for the glass composition 27%TlI-20%Ag2S-53%As2S3. This composition of chalcogenide glass was selected as a membrane material for the Tl-selective chemical sensor displaying a value of the electrode function of 57 mV/pTl and a detection limit of 3 × 10−6 mol l−1.