Résumé:
The aim of this work is to characterize magnesium-lanthanum alloys elaborated by means of an electrodeposition technique using an aqueous solution based on magnesium chloride and lanthanum nitrate. The Mg-La alloys are deposited on a copper plate used as a cathode. Morphology, chemical and structural composition are investigated by SEM, EDS, XRD and FTIR. At first, the voltage effect on the characteristics of the as-deposited powders is
studied through sic values (3, 3.5, 4, 6, 8 and 10 V). Indeed, morphological characterization revealed the formation of heterogeneous chemical structures on the surface of the electrode and the size of the aggregates decrease by increasing potential value. EDS analysis shows the presence of three major elements (Mg, La and O) with a little amount of Cl. The weight percentages of Mg and O increase whereas the one of La decreases with the voltage increase.
X-ray results showed that the obtained deposit can be readily indexed to two phases, which are Mg(OH)2 and La(OH)3. FTIR analysis confirms the presence of the two phases identified in XRD diffractograms. In a second step, the effect of concentration on the as-prepared powders is studied for different values of voltage and by varying the mass concentration of La (20, 40 and 60%). The FTIR and XRD analyses also suggest the existence of two phases mentioned
above. It is noted that the intensities and the transmittances vary by varying voltage and concentration. As a last study, the effect of the nature of the cathode has been studied by working with three types of cathodes (copper, graphite and an alloy of aluminum and chromium).
