Well-defined Gd(OH)CO3, Gd2O(CO3)2·H2O, and Gd2O3 compounds with multiform morphologies and adjustable particle sizes: Synthesis, formation process, and luminescence properties

Abstract

A variety of monodisperse size-tunable Gd(OH)CO3 nanospheres and Gd2O(CO3)2·H2O microplates have been synthesized via a facile homogeneous precipitation route with a mixing solvent of isopropanol (IPA) and H2O. The morphology and particle size of the gadolinium compounds can be tuned in a controlled manner by simply adjusting the volume ratio of IPA/H2O in solvent or reaction temperature and time. Both the amorphous Gd(OH)CO3 nanospheres and crystalline Gd2O(CO3)2·H2O microplates have been transformed into cubic phase of Gd2O3 after a calcination process in air. Interestingly, the Gd2O3 products perfectly inherit the well-defined morphology, good unifomity and dispersity of the precursor samples except for a shrinkage in particle size due to crystallization and coalescence at high temperature. The Gd2O3:Eu3+ and Gd2O(CO3)2·H2O:Tb3+ samples show red and green emission colors under ultraviolet excitation, and Gd2O3:Yb,Ln3+ (Ln = Er and Ho) samples exhibit characteristic orange-red and green emissions when excited at near-infrared (NIR) excitation. The morphology- and particle size-dependent luminescence performances of phosphors are studied in detail. Moreover, the light emitting diode (LED) devices fabricated with the corresponding down-conversion or up-conversion phosphors can display dazzling characteristic multicolor emissions, revealing that the as-synthesized luminescent materials have potential application prospect in the fields of LEDs, light display systems, and optoelectronic devices.