Jiyang Chen

Strain rate sensitivity of a nanocrystalline Cu-Ni-P alloy

Nanoindentation technique was used to measure the strain rate sensitivity (m) of a nanocrystalline Cu-Ni-P alloy prepared by means of electrodeposition. The m. value decreases from 0.034 to 0.018 when the nominal grain size increases from 7 urn to 33 nm. Both In values of the alloy are obviously lower than those of the pure Cu with similar grain size, implying that P segregation at grain boundaries might play a key role in retarding grain boundary activities as compared to pure Cu samples.

Fluorescence emission enhancement of transparent Nd:YSAG ceramics by Sc2O3 doping

Up to 40% substitution of scandium for aluminum in YAG ceramics has been achieved, and the transparent Nd-doped Y3ScxAl(5−x)O12(Nd:YSAG) ceramics were successfully fabricated by sintering nanosized powder compacts under H2 atmosphere. It was found that 40% scandium substitution for aluminum can significantly enhance the light-emission intensity around 1064 nm of the Nd:YSAG ceramics by 2-3 times as compared with Nd:YAG single crystal without Sc2O3 doping when pumped with the same 808 nm diode laser. In addition, the material was found to have prolonged fluorescence lifetime.

Synthesis of (Y,Gd)2O3:Eu nanopowder by a novel co-precipitation processing

Nano-sized (Y,Gd) 2 O 3 :Eu powders were synthesized by a novel co-precipitation processing in which a mixture of ammonium hydroxide and ammonium hydrogen carbonate was adopted as a complex precipitant. Evolution behaviors of precursors during calcinations were studied by means of thermogravimetry-differential scanning calorimetry-mass spectrum, Fourier transform infrared, x-ray diffraction, scanning electron microscopy, and transmission electron microscopy in detail. Nano-sized (Y,Gd) 2 O 3 :Eu powder as prepared possessed a primary grain size of about 30 nm and specific surface area of 38 m 2 /g after being calcined at 850 °C for 2 h, showing much finer grains and less agglomeration. The as prepared nanopowder shows intense luminescence at 611nm under x-ray or ultraviolet excitation. Transparent (Y,Gd) 2 O 3 :Eu ceramics can also be fabricated using this high sinterable nanopowder.