Various compositions of Ba
1-α-βSr
αEu
βMgl
1-γ MnγAl
10 O
17 (BAM) phosphors were prepared. Their emission spectra and the dependence of efficiency on temperature under 254nm excitation were studied. The more α and/or/β values, the longer the emission wavelength of Eu
2+ and the lower the efficiency at high temperature. A configurational coordinate model shows that these changes are due to a shortening of the Eu
2+-0
2- distance in the phosphor crystal. Furthermore, tricolor fluorescent lamps, which use one of these phosphors as the blue component, were simulated. It was calculated that, by increasing α or β from the conventional values of α=0, β=0.1 and γ=0.02, R
a can be increased without a reduction in luminous flux. The higher the color temperature of the lamp, the more its Ra and luminous flux depend on the composition of BAM. The maximum R
a achieved by changing the composition of BAM in each color temperature increases with an increase in the color temperature, while the luminous flux decreases. R
a = 90 is predicted for a lamp in which the phosphor layer consists of a mixture of only three kinds of phosphors: BAM with α=0.3, β=0.1 and γ=0.015, Y
20
3: Eu and LaPO
4: Ce, Tb. Two kinds of lamps were prepared and tested, and the simulation results were confirmed.
View full abstract