NMR provides detailed structural information and the charge compensation for the Na+. A comprehensive structural characterization of a fluorophosphotellurite glass system.

This work concerns different methods to synthesize rare earth fluorides by using liquid and solid state hexafluorophosphates. Various [PF6]− sources were compared, i.e. [BMIM][PF6], [TBA][PF6] and KPF6. Furthermore, the required reaction times and temperatures have been determined by XRD measurements. It turned out that [TBA][PF6] reacts even in the solid state at moderate temperatures to yield single phase LaF3. The use of hydroxides and oxides instead of the commonly employed nitrates as rare earth educts was successfully attempted. The reaction with rare earth hydroxide showed some peculiarities which were traced back to the specific reaction between HF and OH−. The reaction between [TBA][PF6] and La(OH)3 was studied in detail via the determination of oxygen and nitrogen concentrations as well as solid-state 19F and 139La nuclear magnetic resonance (NMR).

The magnesium-rich intermetallic compounds RE 3Ag4Mg12 (RE = Y, La–Nd, Sm–Dy, Yb) and AE 3Ag4Mg12 (AE = Ca, Sr) were synthesized from the elements in sealed tantalum ampoules through heat treatment in an induction furnace. X-ray powder diffraction studies confirm the hexagonal Gd3Ru4Al12 type structure, space group P63/mmc. Three structures were refined from single crystal X-ray diffractometer data: a = 973.47(5), c = 1037.19(5) pm, wR2 = 0.0296, 660 F 2 values, 30 variables for Gd3Ag3.82(1)Mg12.18(1), a = 985.27(9), c = 1047.34(9) pm, wR2 = 0.0367, 716 F 2 values, 29 variables for Yb3Ag3.73(1)Mg12.27(1) and a = 992.41(8), c = 1050.41(8) pm, wR2 = 0.0373, 347 F 2 values, 28 variables for Ca3Ag3.63(1)Mg12.37(1). Refinements of the occupancy parameters revealed substantial Ag/Mg mixing within the silver-magnesium substructure, a consequence of the Ag@Mg8 coordination. The alkaline earth and rare earth atoms build Kagome networks. Temperature dependent magnetic susceptibility measurements indicate diamagnetism/Pauli paramagnetism for the compounds with Ca, Sr, Y and YbII, while the others with the trivalent rare earth elements are Curie-Weiss paramagnets. Most compounds order antiferromagnetically at T N  = 4.4(1) K (RE = Pr), 34.6(1) K (RE = Gd) and 23.5(1) K (RE = Tb) while Eu3Ag4Mg12 is a ferromagnet (T C  = 19.1(1) K). 151Eu Mössbauer spectra confirm divalent europium (δ = −9.88(1) mm s−1). Full magnetic hyperfine field splitting (18.4(1) T) is observed at 6 K. Yb3Ag4Mg12 shows a single resonance in its 171Yb solid state NMR spectrum at 6991 ppm at 300 K indicating a strong, positive Knight shift.

Several ternary rare-earth metals containing titanium aluminum intermetallics in the RE2TiAl3 series (RE = Y, Gd–Lu) have been synthesized from the elements using arc-melting techniques. All compounds crystallize in the trigonal crystal system with rhombohedral space group R3-m (Z = 3) and lattice parameters ranging between a = 582–570 and c = 1353–1358 pm. They adopt the Mg2Ni3Si-type structure, which is an ordered superstructure of the cubic Laves phase MgCu2 and has been observed for Al intermetallics for the first time. Tetrahedral [TiAl3] entities that are connected over all corners form a network where the empty [TiAl3] tetrahedra exhibit a full Ti/Al ordering based on the single crystal results. The Al atoms are arranged into 63 Kagomé nets, while the Ti atoms connect these nets over the triangular units. In the cavities of this three-dimensional arrangement, the RE cations can be found forming a distorted diamond-type substructure. Magnetic measurements revealed that Y2TiAl3 and Lu2TiAl3 are Pauli paramagnetic substances, in line with the metallic character. The other compounds exhibit paramagnetism with antiferromagnetic ordering at a maximum Néel temperature of TN = 26.1(1) K for Gd2TiAl3.

To develop solid-state batteries with high power and energy densities, solid electrolytes with fast Li + transport are required. Superionic lithium argyrodites have proven to be a versatile system, in which superior ionic conductivities can be achieved by elemental substitutions. Herein, we report the novel selenophosphate-based lithium argyrodites Li 6−x PSe 5−x Br 1+x (0 ≤ x ≤ 0.2) exhibiting ionic conductivities up to 8.5 mS•cm −1 and uncover the origin of their fast Li + transport. Rietveld refinement of neutron powder diffraction data reveals a better interconnection of the Li + cages compared to the thiophosphate analogue Li 6 PS 5 Br, by the occupation of two additional Li + sites, facilitating fast Li + transport. Additionally, a larger unit cell volume, lattice softening, and higher structural disorder between halide and chalcogenide are unveiled. The application of Li 5.85 PSe 4.85 Br 1.15 as the catholyte in In/LiIn|Li 6 PS 5 Br|LiNi 0.83 Co 0.11 Mn 0.06 O 2 :Li 5.85 PSe 4.85 Br 1.15 solidstate batteries leads to severe degradation upon charging of the cell, revealing that selenophosphate-based lithium argyrodites are not suitable for applications in lithium nickel cobalt manganese oxide-based solid-state batteries from a performance perspective. This work further expands on the understanding of the structure−transport relationship in Li + conducting argyrodites and re-emphasizes the necessity to consider chemical and electrochemical stability of solid electrolytes against the active materials when developing fast Li + conductors.