Possibility of adjusting the photoluminescence spectrum of Ca scheelites to the emission spectrum of incandescent lamps: [$n$CaWO$_{4}$-$(1-n)$CaMoO$_{4}$] : Eu$^{3+}$ solid solutions

The specific features of the photoluminescence of [$n$CaWO$_{4}$-$(1-n)$CaMoO$_{4}$] : Eu$^{3+}$ solid solutions with the scheelite structure are examined using X-ray phase analysis and photoluminescence, Raman scattering, and diffuse reflectance spectroscopy. The studied features are associated with a change in the long- and short-range orders of the crystal lattice upon variations in the composition of solutions in the range $n$ = 0–1.0 (with a pitch of 0.2) at a concentration of red photoluminescence activator Eu$^{3+}$ of 2 mol %. The mechanism of the modification of photoluminescence of solid solutions upon variations in their composition has been discussed. Anomalies in the variations in parameters of the crystal lattice, its short-range order, and luminescence spectra have been observed in the transition from pure compounds CaMoO$_{4}$ : Eu$^{3+}$ and CaWO$_{4}$ : Eu$^{3+}$ to solutions; the concentration of Eu$^{3+}$ ions in the centrosymmetric localization increases (decreases) in the transition from the molybdate (tungstate). It has been demonstrated that the spectral radiant emittance of solid solution [0.4CaWO$_{4}$-0.6CaMoO$_{4}$] : Eu$^{3+}$ (2 mol %) is the closest to that of an incandescent lamp.