The synthesis, crystal structure and multicolour up-conversion fluorescence of Yb3+/Ln3+ (Ln = Ho, Er, Tm) codoped orthorhombic lutetium oxyfluorides

Abstract

For the first time, undoped and Yb 3+ /Ln 3+ (Ln ¼ Ho, Er, Tm) codoped orthorhombic lutetium oxyfluorides have been fabricated via a facile stepwise route involving room temperature co-precipitation and a subsequent thermal decomposition procedure. The phase formation, crystal structure, particle morphologies and up-conversion (UC) luminescence were investigated by means of powder X-ray diffraction, TEM, IR, thermal and luminescence spectroscopy. It has been found that the intermediate Lu(CO 3 ) 1Àx (OH) y F 1+2xÀy precursor plays an essential role in the formation of the final metastable Lu n O nÀ1 F n+2 Vernier phase. Multicolour up-conversion has been achieved in the Yb 3+ /Tm 3+ , Yb 3+ /Ho 3+ and Yb 3+ /Er 3+ codoped samples under near-infrared excitation (l ¼ 980 nm) and, notably, the Yb 3+ /Er 3+ codoping yields an almost single-band red emission at about 660 nm. A short Ln 3+ -Ln 3+ distance combined with the multiple doping sites in the low symmetry (C 1 and C s ) host lattice are considered responsible for the effective energy transfer and, therefore, the intense up-conversion emission. The present work, together with previous studies on the UC performance of Vernier phase yttrium oxyfluorides, illustrates that the Vernier phase oxyfluorides are promising up-conversion host materials for lanthanide ions in a variety of applications such as bioprobes and chromatic displays.

Size/morphology induced tunable luminescence in upconversion crystals: ultra-strong single-band emission and underlying mechanisms

“…S1 and S2 †) suggests that all as-prepared samples are of the ortho-rhombic Lu n O n−1 F n+2 phase. 19,21 The value of n is further calculated to be 5 from the refinement results, confirming the formation of the Lu 5 O 4 F 7 single phase. The appearance of the characteristic absorption peaks in absorption spectra indicates that Er 3+ and Yb 3+ ions have been introduced into the crystal structure (Fig.…”

Controlled synthesis of β-NaYF4:Yb3+/Er3+ microstructures with morphology- and size-dependent upconversion luminescence

“…Until now, a variety of host materials including oxides [28,29], oxyfluorides [6,30], fluorides [8,31], and chloride [32,33], have been reported to be host lattices for performing multicolor UC emissions. Among them, hexagonal NaYF 4 (ȕ-NaYF 4 ) is regarded as excellent host matrix for achieving highly efficient UC emission of lanthanide ions (Ln 3+ ), owing to its low photon energy, low nonradiative decay rates, and high radiative emission rates [34].…”

Silica-Coated Ga(III)-Doped ZnO: Yb3+, Tm3+ Upconversion Nanoparticles for High-Resolution in Vivo Bioimaging using Near-Infrared to Near-Infrared Upconversion Emission

“…Upconverison nanoparitcles (UCNPs) have drawn a great deal of attention because of their unique upconversion luminescence property and a wide variety of biological applications, such as bioimaging, photodynamic therapy, biomarker, and biological probe. − UCNPs have the ability to convert near-infrared (NIR) excitation radiation into visible light, which is anti-Stokes luminescence . UCNPs provide the highest signal-to-noise ratio, and low toxicity for in vitro imaging is reliable and effective, but it suffers from limited stability and lacked high resolution for bioimaging practical applications. − The luminescence properties of UCNPs are closely related to those of host materials.…”