Abstract

Modulated differential scanning calorimetry (MDSC), thermogravimetric analysis (TGA) and electrical impedance spectroscopy (EIS), were used to study the thermal and electrical properties of the (1−x)CsHSeO4-xKHSeO4 binary system in the concentration range x = 0.0 – 0.7. The sample CsHSeO4 was prepared using Cs2CO3 and H2SeO3 (Aldrich), by a solution technique, followed by a slow evaporation at room temperature in presence of CaCl2. For the KHSeO4 sample, we used K2CO3 and H2SeO3 (Aldrich) following the same procedure. Pure CsHSeO4 (x = 0.0) shows three endothermic anomalies at around 80, 130 and 172°C, respectively. The three anomalies of CsHSeO4 are affected by the KHSeO4 content, specially the second anomaly which tends to disappear as the KHSeO4 content increases. The TGA curves show that all the samples start to lose weight above 120°C, indicating possible dehydration reactions similar to those found in alkaline acid salts, phosphate and sulphates that may explain the highly proton-conducting phases found in these compounds at high temperatures, which reached values of the order of 10-2 (Ω·cm)-1.