DETERMINATION OF THE OPTIMUM EU3+-CONCENTRATION IN LAALO3 - EU-PHOSPHORS BY X-RAY-DIFFRACTION AND FLUORESCENCE MEASUREMENTS

Combining X-ray powder diffraction with fluorescence measurements is an efficient way to determine the optimum activator concentration of inorganic phosphors. La1-xEuxAlO3 samples (perowskite structure), prepared by solid state reactions with 0.5 < x < 5.0 at 1480 K, were investigated by both analytical methods. The luminescence emission spectra show strong 5D0-F-7(1) and 5D0-7D2 transitions and fluorescence intensity reaches a maximum at 1 mol% Eu3+. X-ray diffraction shows the formation of an EuAlO3 phase at Eu3+ concentrations above 1 mol%. Below 1 mol%, Eu3+ substitutes for La3+, as can be seen from the change in the lattice constant c.