THERMAL STUDY OF THE PHASE-TRANSITIONS IN POTASSIUM HYDROGEN SULFATE KHSO4

We report on some thermal properties (specific heat capacity C-p, ther mal conductivity lambda, and thermal diffusivity sigma) in addition to the differential thermal analysis thermogram and thermogravimetric an alysis for potassium hydrogen sulphate (KHS), KHSO4. The accurate meas urements of the above-mentioned parameters as functions of temperature revealed that the compound undergoes two structural phase transitions around 100 degrees C and 175 degrees. It seems also likely that the c ompound behaves as a poorly conducting material and hence the main mec hanism of the heat transfer is due to phonons. The data are correlated to the crystal structure including the two different HSO4- ions.