Synthesis, characterization, shape-preserved transformation, and optical properties of La(OH) 3, La 2O 2CO 3, and La 2O 3 nanorods

Abstract

A simple method to directly synthesize stable and crystalline pure phase La(OH) 3 nanorods, with a diameter of around 15 nm and lengths in the range of 120–200 nm, was developed using cationic surfactant (cetyltrimethylammonium bromide, CTAB). The obtained La(OH) 3 nanorods can be successfully converted to La 2O 2CO 3 and La 2O 3 nanorods via calcination under appropriate conditions. Analytical methods such as X-ray diffraction (XRD) spectra, Fourier transformed infrared (FTIR) spectrum, differential scanning calorimetry and thermogravimetric analysis (DSC–TGA), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM) were employed to characterize the morphology and microstructure of the final products. The results reveal that La(OH) 3 nanorods were shape-preserved and transformed to La 2O 2CO 3 nanorods at 400 °C for 2 h and to La 2O 3 nanorods at 800 °C for 2 h, respectively. TEM images indicate that the as-obtained La 2O 2CO 3 and La 2O 3 entirely consist of uniform nanorods in high yield with diameters of about 15 nm and 23 nm, lengths of 200–300 nm and 300–500 nm, respectively. The formation mechanism of the La(OH) 3, La 2O 2CO 3 and La 2O 3 nanorods was investigated. Room-temperature photoluminescence (RTPL) properties were investigated under the excitation of 275 nm. The 5 D 3 → 7 F j ( j = 2–6) emission peaks at the wavelength below 500 nm were found in the RTPL spectra.