Abstract
Thermoelectric materials of the Fe-Al binary system were prepared at 423 K by electrodeposition in molten salts of the AlCl3-NaCl-KCl-FeCl2 quaternary system. The effects of the current density at the constant content of FeCl2 were investigated in addition to the FeCl2 content at the constant current density on the compositions and morphologies of the electrodeposited Fe-Al alloy films. When the Fe-Al alloy films were electrodeposited in the 63.59 mol%AlCl3-25.83 mol%NaCl-9.94 mol%KCl-0.64 mol%FeCl2, the constant molar ratio for FeCl2 to AlCl3 was 1:100, the Al contents electrodeposited in the film were increased as a function of the applied current density followed by morphological change to a powder over 150 Am－2, indicating that the current density for smooth film preparation was 100 Am－2. At constant current density of 100 Am－2, the various Al contents in the films were obtained as a function of the FeCl2 content in the molten salt, resulting in the significant increase of Al content below 0.5 mol% FeCl2 in the molten salt. Electromotive force was generated by a temperature difference on the obtained Fe-Al alloy films. The sign of generated electromotive force, the type of thermoelectric conversion, depended on the Fe-Al alloy film composition. These obtained results clarifying the condition of electrolysis to control the composition determining thermoelectric property of the film are expected to be useful to develop thermoelectric devices that use Fe-Al film.
