Eu^sup 3+^:KY(MoO^sub 4^)^sub 2^: A novel anisotropic red-emitting material with a layered structure

We report on the crystal growth, structure determination and the vibronic and spectroscopic properties of a novel red-emitting anisotropic crystal featured by a layered structure, the Eu3+-doped orthorhombic potassium yttrium double molybdate crystal, KY(MoO4)2. The transition probabilities of Eu3+ ions are determined within the Judd-Ofelt theory. The stimulated-emission cross-sections are calculated for the 5D0 → 7FJ transitions of Eu3+ with polarized light. The maximum σSE reaches 11.4 × 10−20 cm2 at 613.9 nm for E || c. The strong anisotropy of the spectroscopic properties of Eu3+ is attributed to the layered structure of KY(MoO4)2. The lifetime of the 5D0 state is 0.65 ms. Under UV excitation, Eu:KY(MoO4)2 provides red emission (CIE 1931 coordinates, x = 0.665 and y = 0.335) with almost unity color purity. Eu3+ ions are studied as structural probes, revealing a single type of site (C2 symmetry). The polarization-anisotropy of the purely magnetic-dipole 5D0 → 7F1 transition is discussed. Eu:KY(MoO4)2 is promising for red phosphors and deep-red lasers.