Abstract
A set of Eu(3+)-doped molybdates, Y(2-)xEuxMo(3)O(12) (x = 0.04; 0.16; 0.2; 0.4; 0.8; 1; 1.6; 2), was synthesized using a solid-state technique and their properties studied as a function of Eu(3+) concentration. X-ray diffraction showed that the replacement of Y(3+) with larger Eu(3+) resulted in a transformation from orthorhombic (low doping concentrations) through tetragonal (high doping concentrations), reaching monoclinic structure for full replacement in Eu(2)Mo(3)O(12). The intensity of typical Eu(3+) red emission slightly increases in the orthorhombic structure then rises significantly with dopant concentration and has the highest value for the tetragonal Y(2)Mo(3)O(12):80mol% Eu(3+). Further, the complete substitution of Y(3+) with Eu(3+) in the case of monoclinic Eu(2)Mo(3)O(12) leads to decreased emission intensity. Lifetime follows a similar trend; it is lower in the orthorhombic structure, reaching slightly higher values for the tetragonal structure and showing a strong decrease for monoclinic Eu(2)Mo(3)O(12). Temperature-sensing properties of the sample with the highest red Eu(3+) emission, Y(2)Mo(3)O(12):80mol% Eu(3+), were analyzed by the luminescence intensity ratio method. For the first time, the peak-sharpening algorithm was employed to separate overlapping peaks in luminescence thermometry, in contrast to the peak deconvolution method. The Sr (relative sensitivity) value of 2.8 % K(-1) was obtained at room temperature.