J.J. Yu

A new emission band of Eu2+ and its efficient energy transfer to Mn2+ in Sr2Mg3P4O15:Mn2+, Eu2+

Eu(2+) singly and Eu(2+), Mn(2+) co-doped Sr(2)Mg(3)P(4)O(15) exhibit not only the well known blue emission band of Eu(2+) peaking at 448 nm but also a new band at 399 nm in violet. They are attributed to Eu(2+) on different Sr(2+) sites. The Eu(2+) for the violet band can transfer energy to the red emitting Mn(2+) more efficiently than Eu(2+) for the blue band. The new Eu(2+) band could enable Sr(2)Mg(3)P(4)O(15):Mn(2+), Eu(2+) to be a promising phosphor for enriching the red component of white LEDs.

Temperature dependence of impact deformation behavior of single crystal Ni based superalloy

The impact test was carried out to investigate the intermediate temperature brittleness of single crystal Ni based superalloy. The samples were impacted at the velocity of ∼5 m s− 1. The results showed that the impact toughness also exhibited intermediate temperature brittleness, which is similar to the situation in tensile. The samples showed the highest impact toughness at 600°C but exhibited the lowest impact toughness at 760°C. Results showed that the variety of impact toughness was due to the deformation mechanism. At 600°C, a/2 < 110> dislocation slips on the {111} slip system were attributed to the high impact toughness; however, a/2 < 110> dislocation slips from octahedral {111} planes to cubic {100} planes resulted in significant work hardening, leading to the decrease of impact toughness.