Scheelite related compounds (A′,A″) n [(B′,B″)O4] m with B′, B″ = W and/or Mo are promising new light-emitting materials for photonic applications, including phosphor converted LEDs (light-emitting diodes). In this paper, the creation and ordering of A-cation vacancies and the effect of cation substitutions in the scheelite-type framework are investigated as a factor for controlling the scheelite-type structure and luminescent properties. CaGd2(1–x)Eu2x (MoO4)4(1–y)(WO4)4y (0 ≤ x ≤ 1, 0 ≤ y ≤ 1) solid solutions with scheelite-type structure were synthesized by a solid state method, and their structures were investigated using a combination of transmission electron microscopy techniques and powder X-ray diffraction. Within this series all complex molybdenum oxides have (3 + 2)D incommensurately modulated structures with superspace group I41/a(α,β,0)00(−β,α,0)00, while the structures of all tungstates are (3 + 1)D incommensurately modulated with superspace group I2/b(αβ0)00. In both cases the modulation arises because of cation-vacancy ordering at the A site. The prominent structural motif is formed by columns of A-site vacancies running along the c-axis. These vacant columns occur in rows of two or three aligned along the [1̅10] direction of the scheelite subcell. The replacement of the smaller Gd3+ by the larger Eu3+ at the A-sublattice does not affect the nature of the incommensurate modulation, but an increasing replacement of Mo6+ by W6+ switches the modulation from (3 + 2)D to (3 + 1)D regime. Thus, these solid solutions can be considered as a model system where the incommensurate modulation can be monitored as a function of cation nature while the number of cation vacancies at the A sites remain constant upon the isovalent cation replacement. All compounds’ luminescent properties were measured, and the optical properties were related to the structural properties of the materials. CaGd2(1–x)Eu2x (MoO4)4(1–y)(WO4)4y phosphors emit intense red light dominated by the 5D0–7F2 transition at 612 nm, along with other transitions from the 5D1 and 5D0 excited states. The intensity of the 5D0–7F2 transition reaches a maximum at x = 0.5 for y = 0 and 1.

Al-doped ZnO nanoparticles are synthesized by means of a heating up solution based thermal decomposition method. The synthesis involves a reaction of zinc acetylacetonate hydrate, aluminium acetylacetonate and 1,2-hexadecanediol in the presence of oleic acid and oleyl amine. A proposed reaction mechanism from reagents to monomers is corroborated by analysis of the evolving gases using headspace GC-MS analysis. The Al-doped ZnO nanoparticles synthesized are dynamically stabilized by adsorbed oleate ions, after deprotonation of oleic acid by oleyl amine, as was found by NOESY proton NMR and complementary FTIR spectroscopy. Precession electron diffraction shows a simultaneous increase in lattice parameters with Al concentration. This, together with HAADF-STEM and EDX maps, indicates the incorporation of Al into the ZnO nanoparticles. By the combination of complementary characterization methods during all stages of the synthesis, it is concluded that Al is incorporated into the ZnO wurtzite lattice as a dopant

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The n = 2 Ruddlesden—Popper phases LaSr2CoMnO7 and La1.2Sr1.8CoMnO7 are prepared by a sol—gel method from acetic acid solutions of stoichiometric amounts of La2O3, SrCO3, Co(OAc)2, and Mn(OAc)2 (calcination in flowing oxygen at 1350 °C, 18 h).