Ta ₂O ₅ nanobars and their composites: Synthesis and characterization

Novel Ta ₂O ₅ nanobars anchored on micron-sized carbon spheres were synthesized by the thermal decomposition of pentaethoxy tantalate, Ta(OEt) ₅. This one-step reaction was carried out using the RAPET (Reaction Under Autogenic Pressure at Elevated Temperature) method by dissociating Ta(OEt) ₅ at 800°C for 3 h. The as-prepared Ta ₂O ₅/C nanobar-composite was annealed under air at 500°C for 3 h (eliminating the carbon spheres), resulting in neat Ta ₂O ₅ nanobars. The products, Ta ₂O ₅/C and Ta ₂O ₅ nanobars, were characterized using methods such as electron microscopy (SEM, TEM, HRTEM, SAEDS, EA, EDX) and Powder-XRD. Transmission electron microscope (TEM) images indicated the particle size of the Ta ₂O ₅ nanobars coated on 40-60 nm carbon spheres. The optical properties of the Ta ₂O ₅/C nanobar-composite and the neat Ta ₂O ₅ nanobars were determined by UV-vis absorption spectrometry and their band gaps were found at 265 (4.7 eV) and 260 nm (4.8 eV), respectively. A PL band was also observed for a Ta ₂O ₅/C nanobar-composite and Ta ₂O ₅ nanobars. The above results indicate that Ta ₂O ₅ nanobars have a promising application in optical devices.