Due to the relationship between structure and luminescence properties, detailed crystal structure determination for microcrystalline phosphors is necessary for a profound understanding of materials properties. The yellow phosphor La 3 BaSi 5 N 9 O 2 :Ce 3+ (λ max = 578 nm; fwhm ∼4700 cm −1 ) was characterized by a combination of transmission electron microscopy (TEM) and synchrotron microfocus diffraction as only agglomerates of crystals with a maximum size of a few μm could be obtained yet. La 3 BaSi 5 N 9 O 2 :Ce 3+ was synthesized from LaF 3 , La(NH 2 ) 3 , BaH 2 , Si(NH) 2 , and CeF 3 in a radio frequency furnace. It crystallizes in space group Pmn2 1 (no. 31) with a = 9.5505(8), b = 19.0778(16), c = 12.1134(9) Å, and Z = 8. Its interrupted three-dimensional tetrahedra network contains zehner and dreier rings of vertex-sharing SiN 4 and SiN 2 O 2 tetrahedra. The crystal structure was confirmed by high-resolution TEM and Z-contrast scanning TEM. The element distribution was derived by bond-valence sum calculations. The infrared spectrum proves the absence of N−H bonds.

The nitridosilicate La 3−x Ca 1.5x Si 6 N 11 :Eu 2+ (x ≈ 0.77) was synthesized in a radiofrequency furnace starting from LaF 3 , La(NH 2 ) 3 , CaH 2 , Si(NH) 2 , and EuF 3 . The crystal structure was solved and refined from single-crystal X-ray data in the tetragonal space group P4bm (no. 100) with a = 10.1142(6), c = 4.8988(3) Å, and Z = 2. Thereby, the so far unknown charge balance mechanism in the system (La,-Ca) 3 Si 6 N 11 , which is necessary as bivalent Ca 2+ substitutes trivalent La 3+ , was clarified. Accordingly, charge balance is achieved by incorporation of Ca 2+ on three cation sites, including an additional third site compared to the homeotypic La 3 Si 6 N 11 structure type. The results are supported by Rietveld refinement on powder X-ray diffraction data as well as energy-dispersive X-ray spectroscopy. Fourier transform infrared spectroscopy indicates absence of N−H bonds. An optical band gap of ≈ 4.0 eV was determined using UV/vis reflectance spectroscopy. The Eu 2+ doped compound exhibits a remarkably narrow emission in the yellow-orange spectral range (λ em ≈ 587 nm, fwhm ≈ 60 nm/1700 cm −1 ). Because of the intriguing yellow-orange luminescence, La 3−x Ca 1.5x Si 6 N 11 :Eu 2+ (x ≈ 0.77) is a promising candidate for application in next-generation amber phosphor-converted light emitting diodes.

In this Research Article, we present our results on the optimization of the TiO2 blocking layer to improve the efficiency of organic and hybrid solar cells and make them more competitive with standard silicon devices. The major aim of the present work is to increase the electrical conductivity within the TiO2 blocking layer to guarantee for efficient charge carrier transport and separation. This is realized by optimizing the calcination processes toward an increase in particle/domain size to increase the unpercolated pathways for charge carriers and to get deeper insight into the morphology of the sol-gel produced films.

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The oxonitridosilicate chloride La6Ba3[Si17N29O2]Cl was synthesized by a high-temperature reaction in a radiofrequency furnace starting from LaCl3, BaH2, and the ammonolysis product of Si2Cl6. Diffraction data of a micrometer-sized single crystal were obtained using microfocused synchrotron radiation at beamline ID11 of the ESRF. EDX measurements on the same crystal confirm the chemical composition. The crystal structure [space group P63/m (no. 176), a = 9.8117(14), c = 19.286(6) Å, Z = 2] contains an unprecedented interrupted three-dimensional network of vertex-sharing SiN4 and SiN3O tetrahedra. The SiN4 tetrahedra form dreier rings. Twenty of the latter condense in a way that the Si atoms form icosahedra. Each icosahedron is connected to others via six SiN4 tetrahedra that are part of dreier rings and via six Q(3)-type SiN3O tetrahedra. Rietveld refinements confirm that the final product contains only a small amount of impurities. Lattice energy (MAPLE) and bond-valence sum (BVS) calculations show that the structure is electrostatically well balanced. Infrared spectroscopy confirms the absence of N-H bonds.