Single phase europium-activated gadolinium aluminum borate, Gd 1Ϫx Eu x Al 3 ͑BO 3 ) 4 (0 р x р 1) was obtained by the evaporation of its nitrate solution, and calcination at 900 to 1100°C in air. All the solid solution was identified as the isomorphs of huntite. Eu 3ϩ activated GdAl 3 ͑BO 3 ͒ 4 showed intense red emission with CIE chromaticity coordinates of ͑0.645, 0.330͒ under 147 nm excitation. According to the excitation and emission spectra, the red emission of Eu 3ϩ was decreased under excitation of the vacuum ultraviolet ͑VUV͒ region ͑158-160 nm͒, and increased under excitation UV region ͑258-260 nm͒ with the increase of Eu 3ϩ concentration. In comparison with the absorption data of borates, the 158 nm excitation peak was assigned to the energy level of BO 3 groups. In excitation spectra, the sharp 274 nm peak, corresponding to the 8 S 72 → 6 I 2/11 transition of Gd 3ϩ in addition to the f-f transitions of Eu 3ϩ were observed. Consequently, the emission of Eu 3ϩ was induced by the energy transfer of VUV excitation to the activator Eu 3ϩ ions via the co-activator Gd 3ϩ in GdAl 3 ͑BO 3 ͒ 4 .
Luminancedegradation of blue-emitting phosphor BaMgAl 10 O 17 :Eu caused by the PDP making process and VUV irradiation was studied. The degradation by panel making process was investigated with samples prepared by several panel makers. The least degraded sample maintained 83% luminance after the process. The degradation by VUV was compared for the phosphor degraded by the process and initial phosphor. The luminance of the degraded one by process degraded lesser than non-processed one. Chemical analysis indicated that the degradation was caused by the change in valence of europium in phosphor surface.
Field emission characteristics of graphite nanofibers (GNFs) are studied by operating a scanning atom probe as a field emission microscope. The Fowler-Nordheim plot indicates that the work function of GNF is larger than that of carbon nanotubes and is comparable to tungsten. Field emission patterns indicate that electrons are emitted from the edges of graphene sheets in the direction perpendicular to the GNF axis. The ratio of the field emission voltage and that of the field evaporation voltage implies that the binding between the graphene sheets is weak. The field evaporated cluster ions of carbon and hydrogen indicate that hydrogen is not distributed randomly but is forming the characteristic carbon-hydrogen cluster, C23H2. The proposed structure of the cluster is the triangularly arranged six hexagonal cells with hydrogen terminated two carbon atoms and an extra carbon atom.
The broad bands at around 155 nm for GdAl 3 (BO 3 ) 4 :Eu, at 184 nm for Ca 4 GdO(BO 3 ) 3 :Eu, at 183 nm for Gd 2 SiO 5 :Eu, and at 170 nm for GdAlO 3 :Eu were observed. These bands were assigned to the charge-transfer (CT) transition of Gd 3+ -O 2-. In the excitation spectrum of (Gd,Y)BO 3 :Eu, a broadened excitation band was observed in VUV region. It could be considered that this band was composed of two bands at about 160 and 166 nm. The preceding band was assigned to the BO 3 group absorption. The later one at about 166 nm could be assigned to the CT transition of Gd 3+ -O 2-, according to the result of GdAl 3 (BO 3 ) 4 :Eu, Ca 4 GdO(BO 3 ) 3 :Eu, Gd 2 SiO 5 :Eu, and GdAlO 3 :Eu. The excitation spectra overlapped between the CT transition of Gd 3+ -O 2and BO 3 groups absorption. It caused the emission of Eu 3+ to take place effectively in the trivalent europium-doped (Gd,Y)BO 3 host lattice under 147-nm excitation.
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