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Linarite, PbCuSO4(OH)2, crystallizes as secondary mineral in form of clusters of crystals in Mine du Pradet at Cap Garonne in France. A tiny single crystal was isolated and its structure was refined from synchrotron diffraction data (λ = 0.049592 nm): P121/m1, a = 467.75(2), b = 563.48(4), c = 967.64(5) pm, β = 102.647(5)°, wR = 0.0544, 819 F 2 values and 56 variables. The proton positions were also refined. The Cu2+ cations are located within Cu(OH)2 ribbons and exhibit pronounced Jahn-Teller distortion (d(Cu–O): 2 × 191.9, 2 × 197.3 and 2 × 252.8 pm). The Cu(OH)2 ribbons are condensed with the sulfate tetrahedra and the lead cations. The latter are coordinated to eight oxygen atoms in a slightly anisotropic manner. Calculations of the electron localization function (ELF) of PbO (litharge), PbSO4 (anglesite) and PbCuSO4(OH)2 (linarite) show pronounced lone-pair character for PbO but rather isotropic ELF values around the lead cations in PbSO4 and PbCuSO4(OH)2.

The quaternary tungstates Li3Ba2RE3(WO4)8 (RE = La–Nd, Sm–Ho) were obtained by a ceramic synthesis route and were characterized by powder and single crystal X-ray diffraction. The structures of Li3Ba2Pr3(WO4)8 and Li3Ba2Tb3(WO4)8 were refined from single crystal diffractometer data: RbLiBi2(MoO4)4 type, space group C2/c, a = 528.57(2), b = 1292.39(6), c = 1934.80(10) pm, β = 91.522(4)°, 2151 F2 values, 108 parameters for Li3Ba2Pr3(WO4)8 and a = 520.54(2), b = 1272.03(6), c = 1918.85(10) pm, β = 91.948(4)°, 2020 F2 values, 108 variables for Li3Ba2Tb3(WO4)8. Striking polyhedral building units in these tungstates are WO4 tetrahedra and LiO6 octahedra, while the mixed occupied site and the barium atoms have higher coordination numbers, i.e. RE/Li@O8 and Ba@O10. In addition to the powder quality assessment by means of reflection spectroscopy, the synthesized samples were studied for their suitability as a scintillator material. Therefore, X-ray excited luminescence measurements where performed. Apart from Li3Ba2Ce3(WO4)8 and Li3Ba2Nd3(WO4)8, all compounds show strong emission under X-ray irradiation. Li3Ba2La3(WO4)8 and Li3Ba2Gd3(WO4)8 show blue CT luminescence caused by tungstate units, while the other samples show typical and multiple lines due to well known [Xe]4fn → [Xe]4fn transitions.

The scandium-rich intermetallic compounds Sc50T13In3(T = Ni, Ru, Pd) were synthesized from the elements in sealed tantalum crucibles in an induction furnace. The samples were studied through Guinier powder patterns and their structures were refined from single-crystal X-ray diffractometer data. The Sc50T13In3phases are site occupancy (coloring) variants of the aristotype Ag7+xMg26–x(Fm$$ \bar{3} $$3¯,cF264). Refinements of the occupancy parameters indicated one mixed occupied site for each crystal, leading to the refined compositions Sc50Ni13.16(1)In2.84(1), Sc49.59(1)Ru13In3.41(1), and Sc50Pd13.65(2)In2.35(2). The complex structures can be explained by a condensation of cubes (CN 8), sphenocorona (CN 10), and icosahedra (CN 12). The samples with nickel and palladium are Pauli paramagnets.Graphic abstract

Systematically twinned olivenite (Cu2(AsO4)OH) single crystals from Cap Garonne, Mine du Pradet, France, were studied by X-ray diffraction: P 21/n, a = 822.69(6) pm, b = 861.88(9) pm, c = 594.06(9) pm, β = 90.000(6)°, wR = 0.0224, 1621 F 2 values, 79 variables and a domain ratio of 0.501(1)/0.499(1). The temperature dependence of the magnetic susceptibility was well reproduced with a square-spin cluster model and an antiferromagnetic spin-exchange parameter of J/k B = 157(3) K.

Natural lead dioxide samples (β modification) from Cap Garonne, Mine du Pradet, France and Mount Trevasco, Italy were studied by single crystal X-ray and electron diffraction, clearly manifesting the rutile-type structure. A needle from the Mount Trevasco sample was investigated on a single crystal diffractometer: P42/mnm, a = 495.81(10), c = 338.66(7) pm, wR = 0.0513, 117 F 2 values (all data) and nine variables (293 K data). An additional data set at T = 90 K gave no hint for structural distortions.

This work relates to the synthesis, structural, and spectroscopic characterization of praseodymium and sodium co-doped Sr3(BO3)2. This material was evaluated concerning its suitability as a photo- or radioluminescent UV-C emitting compound. Beyond recording the photoluminescence and radioluminescence, diffuse reflectance and temperature dependent spectra were recorded. Furthermore, the structure refinement based on single crystal X-ray diffraction data as well as morphologic studies by using scanning electron microscopy and dynamic light scattering methods were performed.

This work deals with the spectroscopic properties of single crystalline samples of KTb3F10. Green luminescing KTb3F10 is an efficient UV radiation converter with a quantum yield of about 40% upon UV-A excitation, while it is also an efficient scintillator upon excitation by 20–50 kV X-ray photons. The temperature dependence of the integral photoluminescence as well as the decay time of KTb3F10 monitored for the Tb3+ emission show that the internal quantum yield between 100 and 800 K is almost constant, while the external quantum yield is modulated, likely due to a change in reabsorption at elevated temperatures. In contrast, the low temperature range between 3 and 63 K reveals a change of the local Tb3+ environment in KTb3F10, which is indicated by an anomaly in the heat capacity and by a strong change of the decay time as well as by a distinct shift of the photoluminescence spectra at low temperatures. In addition, temperature dependent magnetic susceptibility measurements and a structure refinement based on single crystal X-ray diffraction data were performed.