Self-templated and self-assembled synthesis of nano/microstructures of Gd-based rare-earth compounds: morphology control, magnetic and luminescence properties

Nearly monodisperse NaGdF4 and GdF3 nanowires/nanorods as well as GdBO3 microplates/microflowers have been successfully prepared by a designed chemical conversion approach using Gd(OH)3 nanowires/nanorods as precursors via a facile hydrothermal approach. The Gd(OH)3 nanowires/nanorods precursors were prepared through a simple hydrothermal process, which then served as sacrificial templates for the fabrication of NaGdF4 and GdF3 nanowires/nanorods as well as GdBO3 microplates/microflowers by a hydrothermal process. The possible formation mechanisms for the corresponding Gd3+-based various products are presented in detail. We have investigated the magnetic properties of the NaGdF4, GdF3, and GdBO3 samples. The as-obtained Eu3+ doped NaGdF4, GdF3, and GdBO3 samples show the strong characteristic red emission of Eu3+ under ultraviolet excitation. Moreover, the luminescence colors of the Eu3+ and Tb3+ co-doped GdBO3 samples can be tuned from red, through orange, yellow and green-yellow, to green by simply adjusting the relative doping concentrations of the activator ions under a single wavelength excitation, which might find potential applications in the fields such as light display systems and optoelectronic devices. More importantly, this simple method is expected to allow the large-scale production of other complex rare-earth compounds with controllable morphologies and sizes, and exploration of the morphology and phase-dependent photoluminescence properties.