Luminescence degradation of hydride vapor-phase epitaxy-grown GaN wafers under electron-beam (e-beam) irradiation was studied. A drastic decrease in the band-edge emission is observed under e-beam irradiation. This degradation may be decomposed into two components: a strong and quick decrease in the first minute and a smaller and more gradual decrease. It is found that the vacuum condition also affects the luminescence of GaN since the degradation amplitude becomes smaller when the specimens are kept in ultrahigh vacuum. These results suggest that the adsorbed species at the surface may affect the luminescence properties of GaN.

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A double perovskite Ca2YSbO6:Eu3+ red-emitting phosphor with high concentration quenching and excellent quantum efficiency was developed to find a potential application in warm WLEDs.

Nickel(II) Oxalate Dihydrate / Thermal Decomposition / Temperature Programmed-XRD / TGA-FTIRThe non-isothermal decomposition of NiC 2 O 4 · 2H 2 O was investigated under a dynamic inert atmosphere using a temperature-programmed X-ray diffractometer (TP-XRD) and a thermogravimetric analyzer coupled to a Fourier-transform infrared spectrometer (TGA-FTIR). Both solid and gaseous products were analyzed in situ. The XRD pattern of the dehydration product did not match data for NiC 2 O 4 reported in the JCPDS file. The thermal decomposition of the dehydration product (NiC 2 O 4 ) took place in two sub-steps, both of which involved CO 2 evolution. Metallic nickel was the final product.