Eu3+/Tb3+-Doped La2O2CO3/La2O3 Nano/Microcrystals with Multiform Morphologies: Facile Synthesis, Growth Mechanism, and Luminescence Properties

LaCO3OH nano/microcrystals with a variety of morphologies/sizes including nanoflakes, microflowers, nano/microrhombuses, two-double microhexagrams sandwichlike microspindles, and peach-nucleus-shaped microcrystals have been synthesized via a facile homogeneous precipitation route under mild conditions. A series of controlled experiments indicate that the pH values in the initial reaction systems, carbon sources, and simple ions (NH4+ and Na+) were responsible for the shape determination of the LaCO3OH products. A possible formation mechanism for these products with diverse architectures has been presented. After annealing at suitable temperatures, LeCO(3)OH was easily converted to La2O2CO3 and La2O3 with the initial morphologies. A systematic study on the photoluminescence and cathodoluminescence properties of Eu3+ - or Tb3+ - doped La2O2CO3/La2O3 samples has been performed in detail. The excitation and site-selective emission spectra were recorded to investigate the microstructure, site symmetry, and difference in the D-5(0)-> F-7(2) transition of Eu3+ ions in La2O2CO3 and La2O3 host lattices. In addition, the dependence of the luminescent intensity on the morphology for the as-prepared La2O2CO3/La2O3:Ln(3+) (Ln = Eu, Tb) samples has been investigated. The ability of generating diverse morphologies and multiemitting colors for different rare-earth activator ion (Ln Eu, Tb) doped La2O2CO3/La2O3 nano/microstructures provides a great opportunity for the systematic evaluation of morphology-dependent luminescence properties, as well as the full exploration of their application in many types of color display fields.