Scheelite related compounds with general formula M_n(XO₄)_m are the subject of hefty interest owing to their optical properties, stability and relatively simple preparation. Eu³⁺-containing scheelites are considered as red-emitting phosphors and the main factors affecting their luminescence are thought to be chemical composition and particle size while the influence of their structure is generally ignored. Here we report eight compounds from the Na_xEu(2−x_{) / 3}MoO₄ series prepared by conventional solid-state reaction and present a detailed analysis of their crystal structures. Six of them have modulated structures, a common feature of SRCs, in which dopant Eu³⁺ ions are orderly distributed. Moreover, different amounts of Eu³⁺ dimers are detected in the modulated structures, characterized by weak satellite reflections appearing in the lower angle part of the XRD patterns. These reflections are indexed and incorporated into Rietveld's refinement using superspace (3 + 1)-dimension symmetry. The remarkable feature of the compounds is that the characteristic luminescence parameters, overall (Q^Eu _L) and intrinsic (Q^Eu _Eu) quantum yields, Eu(⁵D₀) lifetimes, and sensitization efficiencies (η_sens), correlate with the number of Eu³⁺ aggregates, but not directly with the composition x of the materials. This provides an efficient tool for understanding and controlling the luminescence properties of scheelite related compounds.

Layered transition metal dichalcogenides (TMDs) are commonly classified as quasi-two-dimensional materials, meaning that their electronic structure closely resembles that of an individual layer, which results in resistivity anisotropies reaching thousands. Here, we show that this rule does not hold for 1T-TaS₂—a compound with the richest phase diagram among TMDs. Although the onset of charge density wave order makes the in-plane conduction non-metallic, we reveal that the out-of-plane charge transport is metallic and the resistivity anisotropy is close to one. We support our findings with ab initio calculations predicting a pronounced quasi-one-dimensional character of the electronic structure. Consequently, we interpret the highly debated metal-insulator transition in 1T-TaS₂ as a quasi-one-dimensional instability, contrary to the long-standing Mott localisation picture. In a broader context, these findings are relevant for the newly born field of van der Waals heterostructures, where tuning interlayer interactions (e.g., by twist, strain, intercalation, etc.) leads to new emergent phenomena.

Praseodymium molybdate Pr₂(MoO₄)₃ was synthesized using the standard ceramic route. The crystal structure of the material has been successfully solved in superspace group I2/b(αβ0)00 with lattice constants a = 5.30284(4), b = 5.32699(3), c = 11.7935(1) Å, γ = 90.163(1)°, and the modulation vector q = 2/3a* + 0.88810(2)b*. The deviation of the q vector from a rational value allows a description of the structure in terms of nanosize domains with the La₂(MoO₄)₃-like structure separated by stacking faults. Under 450 nm excitation, (³P₀ level) Pr₂(MoO₄)₃ exhibits the characteristic red emission, with the most intense band at 649 nm corresponding to a ³P₀ → ³F₂ transition. Magnetic susceptibility measurements reveal Curie−Weiss paramagnetism with predominating antiferromagnetic interactions between Pr³⁺-magnetic moments and no evidence of magnetic transitions down to T = 5 K.