Luminescence spectra of Eu3+-activated potassium lanthanum and potassium gadolinium phosphate vanadates

The effects of the Eu3+ concentration and PO4/VO4 ratio on the photolumines cence (PL) of K3R1-yEuy(PO4)(x)(VO4)(2-x)(R = La, Gd) phosphate vanadates w ere studied over wide composition ranges. The energies of the Stark compone nts of the F-7(j) (j = 0, 1, 2) levels were determined, and the crystal-fie ld parameters were evaluated. The concentration quenching of Eu3+ luminesce nce was examined. The PL intensity was found to increase with Eu3+ content up to y = 0.3. At higher Eu3+ contents, the PL intensity decreases, without , however, complete luminescence quenching even at y = 1. K3Gd0.7Eu0.3(VO4) (2) and K3Gd0.7Eu0.3PO4)(0.3)(VO4)(1.7) were found to exhibit the brightest photoluminescence.