KHSO4single crystals are found to be pure ionic conductors with no electronic contribution towards the electrical conduction. A new dc electrolysis cell is designed to measure the transport number of protons, which is found to be 1 (TH+quest;1). The currentndash;voltage characteristics along thecaxis are interpreted in terms of a spacehyphen;chargehyphen;limiting current. The number of thermally produced carriersn0and the number of trap centersntin pure KHSO4crystal at 35thinsp;deg;C are calculated to be 8.70times;1013and 2.70times;1014cmminus;3, respectively. The effective mobility of protons at 35thinsp;deg;C is found to be 4.07times;10minus;8cm2thinsp;Vminus;1sdot;secminus;1. On the basis of thermogravimetric studies it is confirmed that a KHSO4single crystal undergoes an irreversible phase transition around 170thinsp;deg;C. The dc conductance of KHSO4single crystals doped with cobalt II is studied in the temperature range of 25 to 165thinsp;deg;C. A break in the conductivity plot is observed suggesting the presence of extrinsic and intrinsic regions. The activation energies for these regions are 0.49plusmn;0.01 and 1.21plusmn;0.01 eV, respectively. The values for the activation entropy for these regions are minus;2.2times;10minus;3and 6.04times;10minus;4eVthinsp;Kminus;1, respectively.
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