PROCESS FOR PREPARING SB-TE-ZN-SN ALLOYS WITH THERMOELECTRIC PROPERTIES

The invention relates to a process for preparing Sb-Te-Zn-Sn alloys with thermoelectric properties by using sequential electrochemical deposition of Sb-Te/Zn-Sn/Sb-Te layers on a Cu sublayer, the alloys being meant to be used for manufacturing thermoelectric generators. According to the invention, the process consists in sequentially depositing Sb-Te and Zn-Sn alloy layers, from different electrolyte baths, using a Cu sublayer as cathode and Pt as anode and a reference electrode of saturated calomel, the electrodeposition being followed by a thermal treatment of homogenization-diffusion in Ar atmosphere, at a temperature of 350...400°C, for 30..120 minutes, the number of layers ranging between 3 and 9, the layer electrodeposition being performed as follows: a. the electrodeposition of the Sb-Te layer is performed by co-deposition in electrolyte solutions having the following composition: 3...5 g/l SbO, 3...6 g/l TeO, 100 g/l HO, 75 g/l tartaric acid as complexing agent, the pH value = 1...2, the voltage ranging between 0.2...0.5 V and a cathodic current density of 1...5 mA/cmat the electrolyte temperature of 20...25°C, and b. the electrodeposition of the Zn-Sn layer is performed by co-deposition in electrolyte solution having the following composition: 40...50 g/l ZnSO, 2...10 g/l SnSO, 100 g/l HSO, 5...10 g/l Al(SO), 50...100g/l gluconic acid as complexing agent, 1...3 g/l phenol as brightening agent, the pH value = 1...2, the voltage 1.5...2.0 V, the cathodic current density ranging between 5...10 mA/cmand the electrolyte temperature of 40...60°C.