Effect of additives on the surface area of oxide supports for catalytic combustion

BaMgAl10O17:Eu2+ phosphors are synthesized by solid-state calcining of BaCO3, Al2O3, MgO, and Eu2O3 with AlF3 as a flux. The structural and optical properties of the blue phosphor are investigated as a function of the europium concentration in BaMgAl10O17 using the neutron and the X-ray powder diffraction methods and luminescence and X-ray absorption near-edge structure (XANES) spectroscopies. The unit cell parameters of BaMgAl10O17:Eu2+ blue phosphor are calculated through the Rietveld refinements of the X-ray and neutron diffraction data. In addition, the maximum electron energy density of the phosphor is calculated using the maximum entropy method to reveal the overall structural changes in BaMgAl10O17 and BaMgAl10O17:Eu2+. The critical concentration is estimated from the concentration dependencies of the absolute quantum efficiency and the intensity of the photoluminescence. The XANES spectrum reveals that nonsubstituted Eu ions exist in the trivalent state above the critical concentration.

S Kimura

Papers

Phase relations relevant to hexagonal barium aluminates