A Route to Grow Oxide Nanostructures Based on Metal Displacement Deposition: Lanthanides Oxy/Hydroxides Characterization

Structure and morphology of nanowires (NWs) and nanotubes (NTs) of LnO/OH (Ln = La, Ce, Sm, Er), grown by displacement reaction inside anodic alumina membranes (AAM), were investigated as function of the deposition time and electrolytic bath temperature. Depositions performed at 6 degrees C gave only tubular morphology for all lanthanides oxides, whose height increased with cementation time up to a complete filling of the template pores. For Sm and La cementation conducted at room temperature, a morphology change from mostly tubular, for short immersion times, to a mixture of NWs and NTs with increasing height was found, whilst for Ce and Er only NTs were found. All nanostructures grown at 60 degrees C showed a NWs morphology and limited heights. Regardless of temperature, a crystalline structure was formed only in the case of CeO2, whilst the other oxy/hydroxides were amorphous or strongly disordered. In the former case, bath temperature influenced slightly crystallite size. However, after cementation at 60 degrees C, few broad and low intensity peaks appear in the diffraction patterns of Sm and Er oxy/hydroxides. Current investigations show that using this simple method it is also possible to grow nanostructures of mixed oxy/hydroxides of different metals. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.047208jes].