The effect of annealing in various atmospheres (N2, H2, NH3 O2 and vacuum) on the 320 nm emission bands of hexagonal boron nitride (h‐BN) powders has been investigated by cathodoluminescence (CL). The CL intensity was decreased by annealing in the N2, H2and NH3 atmospheres at 1200 °C, with H2and NH3 having more effect than N2. On the other hand, the annealing in the O2 atmosphere increased the CL intensity remarkably at annealing temperatures higher than 800 °C. These results suggest that the oxygen located near the particle surface is related to the enhancement of the 320 nm bands in h‐BN. The highest CL intensity, which was obtained at an annealing temperature of 900 °C, reached to about one third of that measured for ZnS:Cu,Al phosphor under the same measurement conditions. The investigation of the powder annealed at higher temperatures in a vacuum indicated that the luminescent centers responsible for these emission bands are thermally stable up to about 1300 °C (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

An yellow-emitting phosphor for white LED application, (Sr,Ba)Si2O2N2:Eu2+, has tabular particle shapes with very broad size distribution, when prepared by a reported method utilizing NH4Cl as a flux. To improve this disadvantage, effects of other fluxes were investigated. Addition of 2 wt.% or less alkali or ammonium nitrate provides more bulky particles of narrower size distribution with little sacrifice of efficiency. Meanwhile, nitrates at high amount of addition and borates as well produce a secondary phase, (Sr,Ba)3Si6O9N4:Eu2+, having poor efficiency, though bulky shapes are obtained. This is probably because some of corner-shared [SiN4]8- tetrahedra are replaced by tetrahedra bridged by O atoms.