Thermal transformation of plumbonacrite/Si films into microstructured Pb/Si ones

In this work we report the transformation of chemically deposited plumbonacrite (Pb10O(OH)6(CO3)6) films induced by thermal annealing in nitrogen atmosphere at temperatures in the 25-700 °C range. The plumbonacrite films were deposited on silicon substrates, at room temperature, by the photo-assisted chemical bath technique using lead acetate as lead precursor and sodium citrate as the complexing agent. The thermal decomposition of plumbonacrite powder was observed by TGA. The crystalline structure and surface morphology of the as-grown and annealed films were analyzed by XRD and SEM, respectively. The results show the thermal decomposition of plumbonacrite into lead oxide at lower temperature and subsequently to elemental lead at higher annealing temperature, accompanied by drastic morphology changes. The resulting Pb films are constituted by a flat, smooth layer with emerging hemispheres of micrometric variable size, in the order of 1-5 mm. These films were partially converted to PbSe by immersion in an aqueous solution containing selenium ions.