Tie Wang

Remarkable differences in photoluminescent properties between LaPO4:Eu one-dimensional nanowires and zero-dimensional nanoparticles

Photoluminescent properties of zero-dimensional LaPO4:Eu nanoparticles (NPs) and one-dimensional nanowires (NWs) prepared by the same wet-chemical synthesis technique were studied and compared. The results indicate that in NP Eu3+ occupied only one site, A, while in NW Eu3+ occupied the same site, A and an additional site B due to crystal anisotropy. Furthermore, the electronic transition rate of D15–∑JFJ7 in the NW increased from 14.9to28.9ms−1 compared to the NP, while the nonradiative transition rate of D15–D05 decreased from 24.1to19.7ms−1. The luminescent quantum efficiency thus improved from 30% to 59%. This work demonstrates that a one-dimensional NW may be a more favorable device than a zero-dimensional NP for photoluminescence.

Modified photoluminescence properties of rare-earth complex/polymer composite fibers prepared by electrospinning

Efficiently luminescent composite fibers of poly (vinyl pyrrolidone) (Mw≈1300000) and europium complex Eu(TTA)3(TPPO)2 (TTA is thenoyltrifluoroacetone; TPPO is triphenylphosphine oxide) were prepared by electrospinning, with average diameters of 200–500nm and lengths of several tens of micrometers. Their photoluminescence properties were studied in comparison to the pure Eu(TTA)3(TPPO)2 complex. It was significant to observe that the thermal stability of photoluminescence in the composite fibers was improved considerably over the pure complex.

Improved photoluminescent properties in one-dimensional LaPO 4 :Eu 3+ nanowires

The photoluminescent properties of one-dimensional LaPO4:Eu nanowires were studied in contrast with the corresponding zero-dimensional nanoparticles, micrometer particles, and micrometer rods. The results indicate that in nanowires Eu3+ ions occupied two different symmetry sites, unlike in nanoparticles and micrometer particles. Furthermore, the radiative transition rate of 5D1 - sigmaJ 7FJ or 5D0 - sigmaJ 7FJ and the internal luminescent quantum efficiency of Eu3+ in the nanowires showed obvious improvement over that in the other powders.

Generation of diamond nuclei on amorphous SiO2 by alternating‐current bias microwave plasma chemical vapor deposition

The nucleation of diamond on the amorphous SiO2 mirror surface has been achieved by means of adding an ac signal to the negative dc bias in the microwave plasma chemical vapor deposition. It is found in experiment that the nucleation of diamond happens only after the frequency of the ac signal exceeds a threshold. The results also show that the diamond nucleation density depends not only on the ac frequency but also on the magnitudes of the ac signal and the dc bias.