Dysprosium- and samarium-activated yttrium vanadates, when properly prepared, are phosphors with constant quantum yield over the range of 2000 to 3450 Å. Correlation of stoichiometry and reflectance is given and an explanation of the possible energy processes is also presented.
R. C. ROPP, "Inorganic Phosphors with Constant Quantum Yield," J. Opt. Soc. Am. 57, 1240-1242 (1967)