A new blue-emitting phosphor LiCaPO4: Eu2+ was synthesized by solid state reaction at a relatively low temperature of 900 °C. It gives a single intense emission band centering at 470 nm, which corresponds to the 4f65d1→4f7 transition of Eu2+. The dependence of luminescence intensities on Eu2+ concentration was investigated. The phosphor, with a single excitation band extending from 250 to 400 nm, could be efficiently excited by near-ultraviolet light-emitting diodes and is believed to be a promising blue-emitting phosphor for white light-emitting diodes. 相似文献
By the aid of temperature- and magnetic-field-dependent Hall effect measurements, we have extracted the multi-carrier transport information in N-doped and N–In codoped p- ZnO thin films grown on Si substrates through mobility spectrum analysis. It is found that owing to the compensation between free electrons and holes, the two-dimensional hole gas from ZnO/Si interface layers becomes determinant and results in the high p-type conductivity and high hole mobility in the ZnO samples. Compared with N-doping, the N–In codoping introduces many In donors and increases acceptor incorporation, as well as enhancing the free hole mobility due to the short-range dipole-like scattering. 相似文献
A procedure for the preparation of a fibrous palladium-containing catalyst for the removal of dissolved oxygen from water
was developed. This procedure includes the preliminary modification of an anionexchanger fiber with carboxylate ions, which
makes it possible to localize metal clusters in a thin subsurface layer of a fiber at the subsequent stages of the ion-exchange
introduction of palladium into the carrier and the reduction of palladium. It was found that the higher activity of fibrous
palladium-containing catalysts based on the citrate forms of anion exchangers, as compared with that of samples based on the
chloride forms, was due to the predominant arrangement of reduced metal clusters on the external surface and an adjacent thin
layer of the fiber. 相似文献
In this paper, we critically assess GRB080503, a short gamma-ray burst with very bright extended emission (about 30 times the gamma-ray fluence of the initial spike). The light curve of the prompt γ-ray emission of GRB080503 resembles that of GRB 060614 which has been suggested to be due to an event from an intermediate mass black hole (IMBH) preying on a star. We therefore propose that GRB080503 is also due to a similar event; the mass of the IMBH is estimated to be about 4.6×104 solar masses, and the engulfed star had about the same mass and size as the Sun. We also estimate that the total burst energy is about 7.67 × 1050 ergs.
If each off-diagonal entry and the sum of each row of a diagonally dominant -matrix are known to certain relative accuracy, then its smallest eigenvalue and the entries of its inverse are known to the same order relative accuracy independent of any condition numbers. In this paper, we devise algorithms that compute these quantities with relative errors in the magnitude of the machine precision. Rounding error analysis and numerical examples are presented to demonstrate the numerical behaviour of the algorithms.