GeO₂ nanorods: synthesis, structural and photoluminescence properties

One-dimensional (1D) GeO₂ nanorods with smooth surface and uniform diameter throughout their length, are synthesized at a relatively lower temperature by hydrothermal technique in the presence of aluminum foil. Further, the nanorods are doped with rare earth element erbium. The products are characterized by XRD, HRTEM, EDS, FTIR, PL techniques. Synthesized nanorods with diameter in the range ∼60–100 nm have core–shell type structure. HRTEM and EDS results reveal that the crystalline core is made by hexagonal α-quartz type GeO₂ and amorphous shell contains compound of Al, Ge and O₂. The role of this amorphous outer layer for unidirectional growth of the nanorods is discussed in detail. PL study reveals that the synthesized nanorods are capable of emitting a strong band in the violet–blue region. Furthermore, the product can emit light in the green and red region. The Er-doped nanorods also show luminescence around 1533 nm under non-resonant excitation confirming the successful inclusion of Er³⁺ ions in the nanorods. Consequently, the as-synthesized materials can be potentially used in a nano-luminescent device in a broad spectrum and as a material of the core in an optical fiber amplifier. (paper)