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Herein we present a Ligand Field Density Functional Theory (LFDFT) based methodology for the analysis of the 4f n -4f nÀ1 5d 1 transitions in rare earth compounds and apply it for the characterization of the show that the occupation of the three undistorted sites allows a quantum-cutting process. However size effects due to the difference between the ionic radii of Pr 3+ and K + as well as Cs + lead to the distortion of the K + -and the Cs + -site, which finally exclude these sites for quantum-cutting. A detailed discussion about the origin of this distortion is also described.

Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the Practical guide to measurement and interpretation of magnetic properties (IUPAC Technical Report)Abstract: Rules are pointed out to protect the magnetochemist from pitfalls in both measurement and interpretation of magnetic data. Carefully chosen magnetic field strengths during magnetic susceptibility measurements guarantee the recording of genuine data. With the help of examples, the effect of too strong applied fields is demonstrated producing magnetic saturation and, for example, quenching of weak ferro-or antiferromagnetic spin-spin couplings. In consequence, the data run the risk of being misinterpreted unless model susceptibility equations are applied that take the field dependence of χ m into consideration. Recommendations are given for the presentation of experimental and theoretical data. The limited applicability of the most overworked formula in paramagnetism, the Curie-Weiss law χ m = C/(T-θ), is clearly presented (magnetically condensed systems, pure spin magnetism). While rough and ready susceptibility formulae are applicable to specific 3d and 4f systems, the complex situation for the remaining d and f centers, including actinides, demands computer programs which consider simultaneously interelectronic repulsion, ligand field potential, spin-orbit coupling, interatomic exchange interactions, and applied magnetic field.

We discuss the applicability of the Angular Overlap Model (AOM) to evaluate the electronic structure of lanthanide compounds, which are currently the subject of incredible interest in the field of luminescent materials. The functioning of phosphors is well established by the f-d transitions, which requires the investigation of both the ground 4f n and excited 4f nÀ1 5d 1 electron configurations of the lanthanides. The computational approach to the problem is based on the effective Hamiltonian adjusted from ligand field theory, but not restricted to it. The AOM parameterization implies the chemical bonding concept.Focusing our interest on this interaction, we take the advantages offered by modern computational tools to extract AOM parameters, which ensure the transparency of the theoretical determination and convey chemical intuitiveness of the non-empirical results. The given model contributes to the understanding of lanthanides in modern phosphors with high or low site symmetry and presents a non-empirical approach using a less sophisticated computational procedure for the rather complex problem of the ligand field of both 4f and 5d open shells.

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The most efficient way to provide domestic lighting nowadays is by light-emitting diodes (LEDs) technology combined with phosphors shifting the blue and UV emission toward a desirable sunlight spectrum. A route in the quest for warm-white light goes toward the discovery and tuning of the lanthanide-based phosphors, a difficult task, in experimental and technical respects. A proper theoretical approach, which is also complicated at the conceptual level and in computing efforts, is however a profitable complement, offering valuable structure-property rationale as a guideline in the search of the best materials. The Eu(2+)-based systems are the prototypes for ideal phosphors, exhibiting a wide range of visible light emission. Using the ligand field concepts in conjunction with density functional theory (DFT), conducted in nonroutine manner, we develop a nonempirical procedure to investigate the 4f(7)-4f(6)5d(1) luminescence of Eu(2+) in the environment of arbitrary ligands, applied here on the CsMgBr3:Eu(2+)-doped material. Providing a salient methodology for the extraction of the relevant ligand field and related parameters from DFT calculations and encompassing the bottleneck of handling large matrices in a model Hamiltonian based on the whole set of 33,462 states, we obtained an excellent match with the experimental spectrum, from first-principles, without any fit or adjustment. This proves that the ligand field density functional theory methodology can be used in the assessment of new materials and rational property design.

Breaking the law: Whereas antiferromagnetic interactions in crystalline carboxylates of lanthanides are often observed, ferromagnetism is unknown. The first example of a ferromagnetic interaction is observed for a crystalline sample of the gadolinium compound [{Gd(OAc)3(H2O)2}2]⋅4 H2O (see picture Gd: gray, O: red).

The flux growth of uranium(IV) oxides presents several challenges, and to the best of our knowledge, only one example has ever been reported. We succeeded in growing two new reduced uranium silicates A2USi6O15 (A = K, Rb) under flux growth conditions in sealed copper tubes. The compounds crystallize in a new structure type with space group C2/c and lattice parameters a = 24.2554(8) Å, b = 7.0916(2) Å, c = 17.0588(6) Å, β = 97.0860(6) ° (K) and a = 24.3902(8) Å, b = 7.1650(2) Å, c = 17.2715(6) Å, β = 96.8600(6) ° (Rb). A2USi6O15 (A = K, Rb) are isocompositional to a previously reported Cs2USi6O15, and the two structures are compared. K2USi6O15 undergoes an interesting crystal-to-crystal structural phase transition at T ≈ 225 K to a triclinic structure, which is accompanied by an intense color change. The magnetic properties of A2USi6O15 (A = K, Rb, Cs) are reported and differ from the magnetism observed in other U(4+) compounds. Calculations are performed on the (UO6)(-8) clusters of K2USi6O15 to study the cause of these unique magnetic properties.