Synthesis and luminescence properties of the lithium-containing lanthanum-oxycarbonate-like borates

The lithium-containing lanthanum-oxycarbonate-like borate, Li0.6La2O2.25(BO3)0.7, has been synthesized by solid-state reactions and was found to be isostructural with the type II lanthanum-oxycarbonate La2O2(CO3). The new compound, lithium-containing lanthanum-oxycarbonate-like borate Li0.6La2O2.25(BO3)0.7 has been synthesized and its structure characterized by the Rietveld method using powder X-ray diffraction data. It crystallizes in space group P63/mmc with lattice parameters of a=b=4.03396(3) Å, c=16.5863(2) Å, V=233.746(4) Å3. The mechanism of the lithium incorporation in the borate is that four Li+ cations replace one (B2O)4+ group, i.e. Li0.6La2O2.25(BO3)0.7 can be described as Li2xLa2O1.5+2.5x(BO3)1−x, x=0.3 and the lithium incorporation stabilized the type II borate. The luminescent properties of Li0.6La2O2.25(BO3)0.7 doped with Eu3+ were studied, indicating a potential application in white light emitting diodes (WLEDs). - Graphical abstract: The similar compounds of the new compound Li0.6La2O2.25(BO3)0.7. Projections along the b-axes of crystal structures for (a) La2O2CO3-II, (b) A-type La2O3, (c) Li0.52La2O2.52(CO3)0.74. Highlights: ► The new compound Li0.6La2O2.25(BO3)0.7 has been synthesized. ► Its structure is characterized by the Rietveld method using powder X-ray diffraction data. ► This compound crystallizes in space group P63/mmc. ► The mechanism of lithium incorporation in borate is that two Li+ cations replace one (BO0.5)2+ group. ► The Eu3+ doped samples have potential application in WLEDs.